Co-reporter:Joanna Bednarska, Robert Zaleśny, Wojciech Bartkowiak, Borys Ośmiałowski, Miroslav Medved’, and Denis Jacquemin
Journal of Chemical Theory and Computation September 12, 2017 Volume 13(Issue 9) pp:4347-4347
Publication Date(Web):August 4, 2017
DOI:10.1021/acs.jctc.7b00469
This article aims at a quantitative assessment of the performances of a panel of exchange-correlation functionals, including semilocal (BLYP and PBE), global hybrids (B3LYP, PBE0, M06, BHandHLYP, M06-2X, and M06-HF), and range-separated hybrids (CAM-B3LYP, LC-ωPBE, LC-BLYP, ωB97X, and ωB97X-D), in predicting the vibrationally resolved absorption spectra of BF2-carrying compounds. To this end, for 19 difluoroborates as examples, we use, as a metric, the vibrational reorganization energy (λvib) that can be determined based on the computationally efficient linear coupling model (a.k.a. vertical gradient method). The reference values of λvib were determined by employing the CC2 method combined with the cc-pVTZ basis set for a representative subset of molecules. To validate the performances of CC2, comparisons with experimental data have been carried out as well. This study shows that the vibrational reorganization energy, involving Huang–Rhys factors and normal-mode frequencies, can indeed be used to quantify the reliability of functionals in the calculations of the vibrational fine structure of absorption bands, i.e., an accurate prediction of the vibrational reorganization energy leads to absorption band shapes better fitting the selected reference. The CAM-B3LYP, M06-2X, ωB97X-D, ωB97X, and BHandHLYP functionals all deliver vibrational reorganization energies with absolute relative errors smaller than 20% compared to CC2, whereas 10% accuracy can be achieved with the first three functionals. Indeed, the set of examined exchange-correlation functionals can be divided into three groups: (i) BLYP, B3LYP, PBE, PBE0, and M06 yield inaccurate band shapes (λvib,TDDFT < λvib,CC2), (ii) BHandHLYP, CAM-B3LYP, M06-2X, ωB97X, and ωB97X-D provide accurate band shapes (λvib,TDDFT ≈ λvib,CC2), and (iii) LC-ωPBE, LC-BLYP, and M06-HF deliver rather poor band topologies (λvib,TDDFT > λvib,CC2). This study also demonstrates that λvib can be reliably estimated using the CC2 model and the relatively small cc-pVDZ basis set. Therefore, the linear coupling model combined with the CC2/cc-pVDZ level of theory can be used as a very efficient approach to determine λvib values that can be used to select the most adequate functional for more accurate vibronic calculations, e.g., including more refined models and environmental effects.
Co-reporter:Chung-Yang Huang, Aurelio Bonasera, Lachezar Hristov, Yves Garmshausen, Bernd M. Schmidt, Denis Jacquemin, and Stefan Hecht
Journal of the American Chemical Society October 25, 2017 Volume 139(Issue 42) pp:15205-15205
Publication Date(Web):October 11, 2017
DOI:10.1021/jacs.7b08726
Some rare indigo derivatives have been known for a long time to be photochromic upon irradiation with red light, which should be advantageous for many applications. However, the absence of strategies to tune their thermal half-lives by modular molecular design as well as the lack of proper synthetic methods to prepare a variety of such molecules from the parent indigo dye have so far precluded their use. In this work, several synthetic protocols for N-functionalization have been developed, and a variety of N-alkyl and N-aryl indigo derivatives have been prepared. By installation of electron-withdrawing substituents on the N-aryl moieties, the thermal stability of the Z-isomers could be enhanced while maintaining the advantageous photoswitching properties upon irradiation with red light (660 nm LED). Both experimental data and computational results suggest that the ability to tune thermal stability without affecting the dyes’ absorption maxima originates from the twisted geometry of the N-aryl groups. The new indigo photoswitches reported are expected to have a large impact on the development of optical methods and applications in both life and material sciences.
Co-reporter:Claus Hierlinger, Thierry Roisnel, David B. Cordes, Alexandra M. Z. Slawin, Denis Jacquemin, Véronique Guerchais, and Eli Zysman-Colman
Inorganic Chemistry May 1, 2017 Volume 56(Issue 9) pp:5182-5182
Publication Date(Web):April 10, 2017
DOI:10.1021/acs.inorgchem.7b00328
A new family consisting of three luminescent neutral Ir(III) complexes with the unprecedented [Ir(C^N^C)(N^N)Cl] architecture, where C^N^C is a bis(six-membered) chelating tridentate tripod ligand derived from 2-benzhydrylpyridine (bnpy) and N^N is 4,4′-di-tert-butyl-2,2′-bipyridine (dtBubpy), is reported. X-ray crystallography reveals an unexpected and unusual double C–H bond activation of the two distal nonconjugated phenyl rings of the bnpy coupled with a very short Ir–Cl bond trans to the pyridine of the bnpy ligand. Depending on the substitution on the bnpy ligand, phosphorescence, ranging from yellow to red, is observed in dichloromethane solution. A combined study using density functional theory (DFT) and time-dependent DFT (TD-DFT) corroborates the mixed charge-transfer nature of the related excited states.
Co-reporter:Raquel Travieso-Puente, Simon Budzak, Juan Chen, Peter Stacko, Johann T. B. H. Jastrzebski, Denis Jacquemin, and Edwin Otten
Journal of the American Chemical Society March 8, 2017 Volume 139(Issue 9) pp:3328-3328
Publication Date(Web):February 20, 2017
DOI:10.1021/jacs.6b12585
A straightforward synthetic route to arylazoindazoles via nucleophilic aromatic substitution is presented. Upon deprotonation of the NH group, a C6F5-substituted formazan undergoes facile cyclization as a result of intermolecular nucleophilic substitution (SNAr). This new class of azo photoswitches containing an indazole five-membered heterocycle shows photochemical isomerization with high fatigue resistance. In addition, the Z-isomers have long thermal half-lives in the dark of up to several days at room temperature. The fluorinated indazole group offers a handle for further functionalization and tuning of its properties, as it is shown to be susceptible to a subsequent, highly selective nucleophilic displacement reaction.
Co-reporter:Cloé Azarias, Mylène Pawelek, and Denis Jacquemin
The Journal of Physical Chemistry A June 8, 2017 Volume 121(Issue 22) pp:4306-4306
Publication Date(Web):May 17, 2017
DOI:10.1021/acs.jpca.7b03644
Using ab initio approaches accounting for environmental effects, we investigate the ground- and excited-state properties of four subporphyrinoids: subporphyrin, subporphyrazine, tribenzosubporphyrin, and subphthalocyanine. We first show that the selected level of theory, that is DFT(PBE0), is able to reproduce the structure and NMR spectra of all compounds. The aromaticity of these four macrocyclic entities are next quantified and it is showed that these bowl-shape induced molecules present very strong aromatic characters. Next we analyze the spectral signatures of all four compounds using an approach going beyond the vertical approximation. The 0–0 energies are reproduced with a mean absolute deviation smaller than 0.1 eV, and the very good agreement obtained between experimental and theoretical band shapes allows us to unravel the vibronic contributions responsible to the specific band shapes of these subporphyrinoids. Finally, we investigate a large series of substituted subporphyrins, demonstrate the quality of the trends that are obtained with theory and design new compounds presenting red-shifted optical bands.
Co-reporter:Kathy J. Chen;Florent Boucher
The Journal of Physical Chemistry C July 23, 2015 Volume 119(Issue 29) pp:16860-16869
Publication Date(Web):June 24, 2015
DOI:10.1021/acs.jpcc.5b05092
In order to best employ multiphotochromes as complex molecular gates, each isomer should ideally have a distinct optical profile to be selectively addressable. In this ab initio DFT and TD-DFT study, we have modeled the electronic and optical properties of a series of dithienylethene (DTE) dimers grafted onto an anatase (101) surface. We seek to investigate how grafting onto a TiO2 surface modifies the energy levels and UV–visible spectra of the dimers and enhances the asymmetry of the isomers. By extracting information from the density of states, we have qualified the distinct degrees of interaction between the substrate and each isomeric configuration as CO > CC > OC > OO in order of decreasing electronic coupling. We subsequently use this information to interpret the UV–vis spectra computed for the isomers. The results show that the grafted systems present new peaks and shifted S1 energies compared with the isolated photochrome, suggesting that adsorption onto a TiO2 surface may induce an asymmetric character in the DTE dyad.
Co-reporter:Šimon Budzák, Giovanni Scalmani, and Denis Jacquemin
Journal of Chemical Theory and Computation December 12, 2017 Volume 13(Issue 12) pp:6237-6237
Publication Date(Web):November 15, 2017
DOI:10.1021/acs.jctc.7b00921
We present an investigation of the excited-state structural parameters determined for a large set of small compounds with the dual goals of defining reference values for further works and assessing the quality of the geometries obtained with relatively cheap computational approaches. In the first stage, we compare the excited-state geometries obtained with ADC(2), CC2, CCSD, CCSDR(3), CC3, and CASPT2 and large atomic basis sets. It is found that CASPT2 and CC3 results are generally in very good agreement with one another (typical differences of ca. 3 × 10–3 Å) when all electrons are correlated and when the aug-cc-pVTZ atomic basis set is employed with both methods. In a second stage, a statistical analysis reveals that, on the one hand, the excited-state (ES) bond lengths are much more sensitive to the selected level of theory than their ground-state (GS) counterparts and, on the other hand, that CCSDR(3) is probably the most cost-effective method delivering accurate structures. Indeed, CCSD tends to provide too compact multiple bond lengths on an almost systematic basis, whereas both CC2 and ADC(2) tend to exaggerate these bond distances, with more erratic error patterns, especially for the latter method. The deviations are particularly marked for the polarized CO and CN bonds, as well as for the puckering angle in formaldehyde homologues. In the last part of this contribution, we provide a series of CCSDR(3) GS and ES geometries of medium-sized molecules to be used as references in further investigations.
Co-reporter:Cloé Azarias, Chloé Habert, Šimon Budzák, Xavier Blase, Ivan Duchemin, and Denis Jacquemin
The Journal of Physical Chemistry A August 17, 2017 Volume 121(Issue 32) pp:6122-6122
Publication Date(Web):July 24, 2017
DOI:10.1021/acs.jpca.7b05222
Using a large panel of theoretical approaches, namely, CC2, CCSD, CCSDR(3), CC3, ADC(2), ADC(3), CASPT2, time-dependent density functional theory (TD-DFT), and BSE/evGW, the two latter combined with different exchange-correlation functionals, we investigate the lowest singlet transition in 23 n→π* compounds based on the nitroso, thiocarbonyl, carbonyl, and diazo chromophores. First, for 16 small derivatives we compare the transition energies provided by the different wave function approaches to define theoretical best estimates. For this set, it surprisingly turned out that ADC(2) offers a better match with CC3 than ADC(3). Next, we use 10 functionals belonging to the “LYP” and “M06” families and compare the TD-DFT and the BSE/evGW descriptions. The BSE/evGW results are less sensitive than their TD-DFT counterparts to the selected functional, especially in the M06 series. Nevertheless, BSE/evGW delivers larger errors than TD-CAM-B3LYP, which provides extremely accurate results in the present case, especially when the Tamm–Dancoff approximation is applied. In addition, we show that, among the different starting points for BSE/evGW calculations, M06-2X eigenstates stand as the most appropriate. Finally, we confirm that the trends observed on the small compounds pertain in larger molecules.
Co-reporter:Denis JacqueminIvan Duchemin, Aymeric BlondelXavier Blase
Journal of Chemical Theory and Computation 2017 Volume 13(Issue 2) pp:
Publication Date(Web):January 20, 2017
DOI:10.1021/acs.jctc.6b01169
We have evaluated the accuracy of the Bethe-Salpeter singlet–triplet transition energies as well as singlet–triplet and triplet–triplet splittings for 20 organic molecules, using as reference the CC3 values determined by Thiel and co-workers with both the TZVP and aug-cc-pVTZ atomic basis sets. Our excitation energies are obtained on the basis of GW quasiparticle energy levels that are self-consistently converged with respect to the starting DFT eigenvalues. In its current form, BSE/GW is often unable to provide a balanced description of both singlet and triplet excited-states. While the singlet–singlet and triplet–triplet energy separations are obtained accurately, triplets are located too close in energy from the ground-state, by typically −0.55 eV when using standard functionals to generate the starting eigenstates. Applying the Tamm-Dancoff approximation upshifts the BSE triplet energies and allows reducing this error to ca. −0.40 eV, while using M06-HF eigenstates allows a further increase and hence a reduction of the error for triplet states, but at the cost of larger errors for the singlet excited-states. At this stage, the most accurate TD-DFT estimates therefore remain competitive for computing singlet–triplet transition energies. Indeed, with M06-2X, irrespective of the application or not of the Tamm-Dancoff approximation and of the selected atomic basis set, the deviations obtained with TD-DFT are rather small.
Co-reporter:Anna Maria Grabarz, Beata Jędrzejewska, Anna Zakrzewska, Robert Zaleśny, Adèle D. Laurent, Denis JacqueminBorys Ośmiałowski
The Journal of Organic Chemistry 2017 Volume 82(Issue 3) pp:
Publication Date(Web):January 9, 2017
DOI:10.1021/acs.joc.6b02732
In this study we present a new series of phenantridine-based substituted difluoroboranyls. The effects of substitution and double benzannulation on their photophysical properties were examined with experimental techniques and compared with the results obtained for previously reported quinoline and isoquinoline derivatives. The experimental characterizations are supported by state-of-the-art quantum-chemical calculations. In particular, the theoretical calculations were performed to gain insights into the complex nature of the relevant excited-states. These calculations reveal that both the nature of the substituent and its position on the phenyl ring significantly impact the magnitude of the electronic charge transferred upon excitation. Additionally, vibrationally resolved spectra were determined allowing for the analysis of the key vibrations playing a role in the band shapes.
Co-reporter:Daniel Escudero, Ivan DucheminXavier Blase, Denis Jacquemin
The Journal of Physical Chemistry Letters 2017 Volume 8(Issue 5) pp:
Publication Date(Web):February 8, 2017
DOI:10.1021/acs.jpclett.7b00015
Hybrid organic–inorganic semiconductor systems have important applications in both molecular electronics and photoresponsive materials. The characterizations of the interface and of the electronic excited-states of these hybrid systems remain a challenge for state-of-the-art computational methods, as the systems of interest are large. In the present investigation, we present for the first time a many-body Green’s function Bethe–Salpeter investigation of a series of photochromic molecules adsorbed onto TiO2 nanoclusters. On the basis of these studies, the performance of time-dependent density functional theory (TD-DFT) calculations is assessed. In addition, the photochromic properties of different hybrid systems are also evaluated. This work shows that qualitatively different conclusions can be reached with TD-DFT relying on various exchange–correlation functionals for such organic–inorganic interfaces and paves the way to more accurate simulation of many hybrid materials.
Co-reporter:Guangqian Zhang, Denis JacqueminDaniela Buccella
The Journal of Physical Chemistry B 2017 Volume 121(Issue 4) pp:
Publication Date(Web):January 4, 2017
DOI:10.1021/acs.jpcb.6b11045
In this joint theoretical and experimental work, we investigate the properties of Mag-fura-2 and seven structurally related fluorescent sensors designed for the ratiometric detection of Mg2+ cations. The synthesis of three new compounds is described, and the absorption and emission spectra of all of the sensors in both their free and metal-bound forms are reported. A time-dependent density functional theory approach accounting for hydration effects using a hybrid implicit/explicit model is employed to calculate the absorption and fluorescence emission wavelengths, study the origins of the hypsochromic shift caused by metal binding for all of the sensors in this family, and investigate the auxochromic effects of various modifications of the “fura” core. The metal-free forms of the sensors are shown to undergo a strong intramolecular charge transfer upon light absorption, which is largely suppressed by metal complexation, resulting in predominantly locally excited states upon excitation of the metal complexes. Our computational protocol might aid in the design of new generations of fluorescent sensors with low-energy excitation and enhanced properties for ratiometric imaging of metal cations in biological samples.
Co-reporter:Aurélie Perrier, Denis Jacquemin
Tetrahedron 2017 Volume 73, Issue 33(Issue 33) pp:
Publication Date(Web):17 August 2017
DOI:10.1016/j.tet.2017.05.050
[2.2]paracyclophane-bridged imidazole dimers are excellent candidates to build fast photochromic devices with practical applications in full–colour holographic display. Herein, we propose an accurate, yet affordable, computational protocol relying on (TD-)DFT for investigating the structural, thermodynamical and optical properties of these systems, three properties of fundamental importance for their potential applications in fast light modulator devices. Within this theoretical framework, we provide an interpretation of the stepwise two-photon photochromic reaction observed for a symmetric [2.2]paracyclophane-bridged bis(imidazole dimer) and propose a new dissymmetric dimer with potential wavelength-dependent photoactivity.Download high-res image (227KB)Download full-size image
Co-reporter:Adam F. Henwood;James Webster;David Cordes;Alexandra M. Z. Slawin;Eli Zysman-Colman
RSC Advances (2011-Present) 2017 vol. 7(Issue 41) pp:25566-25574
Publication Date(Web):2017/05/10
DOI:10.1039/C7RA03190D
The first examples of phosphorescent platinum(II) complexes bearing pentafluorosulfanyl (–SF5) substituted cyclometalating ligands (C^N) are reported. These complexes are of the form [Pt(C^N)(pivacac)], where pivacac is 2,2′,6,6′-tetramethylheptane-3,5-dionate. Modifying the phenyl ring of the C^N ligand to incorporate one strongly electron-withdrawing –SF5 group has important effects on the photophysical and electrochemical properties of the complex that are dependent on the regiochemistry of the substituent. In a meta position with respect to the Pt–CC^N bond, the substituent exerts a predominantly stabilising effect on the lowest triplet excited state that red-shifts the emission of the complex compared to the reference [Pt(ppy)(pivacac)], 1, where ppy is 2-phenylpyridinato. When the –SF5 group is located para to the Pt–CC^N bond, it does not affect the triplet state directly, and the electron-withdrawing group stabilises the metal-based orbitals, resulting in a blue-shift of the emission. In the solid-state all three complexes are mechanochromic, and can display excimeric emission originating from intermolecular π–π* interactions, but the relative emission intensities of the monomeric and dimeric excited states correlate with the steric congestion of the metal centre, and in particular the regiochemistry of the –SF5 group. We relate these findings with observations in the crystal structures.
Co-reporter:Cloé Azarias;Roberto Russo;Lorenzo Cupellini;Benedetta Mennucci
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 9) pp:6443-6453
Publication Date(Web):2017/03/01
DOI:10.1039/C7CP00427C
The excitation energy transfer (EET) allowing the concentration of the energy has been investigated in several multi-BODIPY architectures with the help of an approach coupling time dependent density functional theory to an implicit solvation scheme, the polarizable continuum model. We have first considered several strategies to compute the electronic coupling in a dyad varying the size of the donor/acceptor units, the bridge, the geometries and conformations. We have next studied the electronic coupling in three different architectures for which the EET rate constants have been experimentally measured both from luminescence and transient absorption data and from Förster theory. A good agreement with experimental values was obtained. Finally, in an effort to further improve these systems, we have designed several series of BODIPY triads, investigating the effect of acidochromism, core modifications, the position of the linkage and chemical substitutions on the EET coupling and rate constant. We show that several architectures allow us to increase the EET rate by one order of magnitude compared to the original compound.
Co-reporter:Zhongrui Chen;Gabriel Canard;Cloé Azarias;Olivier Siri
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 13) pp:5284-5290
Publication Date(Web):2017/06/26
DOI:10.1039/C7NJ00697G
Contrasting with the well mastered azacalix[4]arene, the synthesis and characterization of azacalix[6]arene derivatives remain a challenge for chemists. In this framework, bulky n-octylamino groups appended on 1,3-meta-diaminobenzene 2b can lead to the concomitant and straightforward one-pot formation of azacalix[6]arene 4b and of the thermodynamically favoured azacalix[4]arene 3b through simple consecutive nucleophilic aromatic substitutions. The conformations of 3b and 4b were studied in solution and in the solid state using their X-ray molecular structures, their NMR and UV-Visible spectra combined with first principles TD-DFT calculations. Preliminary solution experiments show that 4b can form a 1 : 1 host–guest complex with C60.
Co-reporter:Anouar Belhboub;Florent Boucher
Journal of Materials Chemistry C 2017 vol. 5(Issue 7) pp:1624-1631
Publication Date(Web):2017/02/16
DOI:10.1039/C6TC05297E
The recent discovery of donor–acceptor Stenhouse adducts (DASAs) as a novel class of visible light activated photochromes has received considerable attention due to their high potential for original applications. Up to now, the experimental and theoretical studies have mainly focused on the intrinsic physico-chemical properties and photoswitching process of these molecules, as well as on the incorporation of DASAs in multi-organized structures. In this context, we propose here the first study, by means of first-principle calculations, of DASA photochromes adsorbed onto titanium dioxide anatase surfaces. By analyzing the density of states, we show that DASAs are electronically more sensitive to the surfaces in the closed compact form than in the extended π-conjugated one, which is unusual for photochromes. This finding is also supported by an analysis of the energy band gap. A charge transfer study is performed to quantify the interactions taking place within the total systems. In addition, the impact of grafting on the optical properties is investigated using time-dependent density functional theory (TD-DFT).
Co-reporter:Yevgen M. Poronik;Leszek M. Mazur;Marek Samoć;Daniel T. Gryko
Journal of Materials Chemistry C 2017 vol. 5(Issue 10) pp:2620-2628
Publication Date(Web):2017/03/09
DOI:10.1039/C7TC00276A
The first route towards pyrrolo[3,2-b]pyrroles containing two azulene moieties at positions 2 and 5 was developed. The key step of this approach is the three-step transformation of pyridine scaffolds into azulene via sequential N-arylation followed by ring-opening and a reaction with cyclopentadiene. The resulting quadrupolar acceptor–donor–acceptor compounds possess interesting optical properties such as bathochromically shifted absorption with the magnitude of the red-shift strongly dependent on the linkage position. Two-photon absorption of these functional dyes is markedly different from that of previously described pyrrolo[3,2-b]pyrroles. The experimental optical spectra were rationalized using time-dependent density functional theory calculations of both the linear and nonlinear optical properties.
Co-reporter:Lucien Lavaud;Zhongrui Chen;Mourad Elhabiri;Gabriel Canard;Olivier Siri
Dalton Transactions 2017 vol. 46(Issue 38) pp:12794-12803
Publication Date(Web):2017/10/03
DOI:10.1039/C7DT01884C
We describe the first isolation of N,N′-disubstituted benzoquinonediimines (QDIs) 2 which revealed drastically different properties compared to N,N′,N′′,N′′′-tetrasubstituted QDIs 1 due to the absence of N-substituents in the “upper part” of the molecule. Three major differences could be highlighted thanks to the present joint experimental and theoretical investigation: (1) the metalation with different metal precursors revealed a specific behaviour in coordination chemistry giving access to novel complexes with unprecedented stoichiometry and remarkable absorption properties. More specifically, a new monoplatinum complex that is able to absorb light from the UV up to the NIR region because of its unique delocalization pathway across the metal centre was obtained; (2) this new class of di-substituted QDIs showed an exceptionally broad pKa range (ΔpKa ∼ 8) that could be explained by the possible tuning of the basicity of each imine which is now attainable; (3) these quinones could be used as reagents in organic synthesis to form the previously unknown N,N′,N′′,N′′′-tetrasubstituted QDIs with tuneable substituents (aryl vs. alkyl), previously unknown, as a new ligand for coordination chemistry.
Co-reporter:Boris Le Guennic;Giovanni Scalmani;Michael J. Frisch;Adèle D. Laurent
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 16) pp:10554-10561
Publication Date(Web):2017/04/19
DOI:10.1039/C7CP01190C
Using a computational approach combining Time-Dependent Density Functional Theory (TD-DFT) and second-order Coupled Cluster (CC2) approaches, we investigate the spectral properties of a large panel of BOIMPY dyes. BOIMPY derivatives constitute a new class of fluorophores that appeared only very recently [Angew. Chem. Int. Ed., 2016, 55, 13340–13344] and display intriguing properties. First, we show that theory is able to reproduce experimental 0–0 energies with reasonable accuracy, and more importantly excellent consistency (R = 0.99). Next, by analyzing the nature of the excited-states, we show that the first electronic transition does not imply a significant charge-transfer character and significantly differs from the one of the parent BODIPYs. Third, we unravel the vibrational modes responsible for the specific band shapes of the BOIMPY derivatives. Finally, using theory to design new compounds, we propose substitution patterns leading to redshifted absorption spectra, up to ca. 1000 nm.
Co-reporter:Fadel Bassal, Adèle D. Laurent, Boris Le Guennic, Denis Jacquemin
Dyes and Pigments 2017 Volume 138(Volume 138) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.dyepig.2016.11.046
•A large number of squaraine dyes are investigated with ab initio methods.•We determine 0-0 energies and band shapes for these dyes.•Pragmatic calculation protocols are proposed.We investigate the electronic excited-states of a large panel of squaraine derivatives with first principles tools taking into account environmental effects, with a focus on 0-0 energies and band shapes. First we show that while TD-DFT yields significantly too large 0-0 energies, correcting the TD-DFT values with ADC(2) provides much more accurate estimates. Second, though the geometric relaxation after photon absorption is limited, this investigation also indicates that using theoretical vertical estimates to approximate the experimental 0-0 energies is not a very appealing approach. In contrast, for experimentally non-fluorescent compounds one can use the measured λmax as an approximation of the 0-0 energy with a minimal loss of accuracy. The proposed computational approach delivers a ca. 0.125 eV accuracy for a large number of compounds and therefore stands as one of the first robust method to predict the optical spectra of this important class of dyes. We also investigate the band shapes of selected derivatives and show that TD-DFT vibronic couplings allow an accurate reproduction of the experimental topologies of both absorption and emission bands.Download high-res image (186KB)Download full-size image
Co-reporter:Gabriel Marchand;Olivier Siri
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 24) pp:15903-15913
Publication Date(Web):2017/06/21
DOI:10.1039/C7CP02600E
Azacalixphyrins (ACP) constitute a new class of macrocycles isoelectronic and isostructural to porphyrins. Herein, we report the first theoretical investigation of the properties of the ACP macrocycles metallated at their centre by titanium, platinum, and iron ions. We considered both the original phenyl-type ACP and new pyridyl-type forms. Our results indicate that the metallation greatly impacts the global structure of the macrocycle through pseudo Jahn–Teller effects, giving rise to a possible conformational transition between D2d and S4 structures. Such an effect could not be found in the metal-free ACPs. In addition, we find that, in contrast to the purely singlet platinum ACPs, and the purely triplet iron ACPs, several spin states are energetically close in the titanium ACPs, especially when weak field ligands are bound in axial positions to the metallic centre. According to TD-DFT calculations, metallation also tunes the optical properties. In particular, the absorption band in the near infrared region undergoes a hypsochromic shift of ca. 100–200 nm when going from the D2d to the S4 structures. We quantify how the addition of electroactive ligands in the axial position can increase or tune down these spectral changes. This contribution therefore supports the development of ACP coordination complexes.
Co-reporter:Arnaud Fihey;Roberto Russo;Lorenzo Cupellini;Benedetta Mennucci
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 3) pp:2044-2052
Publication Date(Web):2017/01/18
DOI:10.1039/C6CP07458H
Dithienylethenes (DTEs) can be assembled to form supramolecular multiphotochromic systems that are highly functional molecular architectures of potential interest for building complex optoelectronic devices. Yet even simple DTE dimers relying on an organic linker may suffer from a partial photoactivity, i.e., only one of the two switches does isomerise. Experimentally, this limited photochromism has been attributed to an excited state energy transfer (EET) between the two DTEs of the multimer; this EET taking place instead of the desired photoinduced cyclisation of the DTE. However, no clear evidences of this phenomenon have been provided so far. In this work we propose the first rationalisation of this potential parasite photoinduced event using a computational approach based on Time-Dependent Density Functional Theory (TD-DFT) for the calculation of the electronic coupling in DTE dimers. Besides quantifying EET in several systems, we dissect the role of through-bond and through-space mechanisms on this process and clarify their dependence on both the nature and length of the bridge separating the two photochromes. The theoretical data obtained in this framework are in full agreement with the experimental outcomes and pave the way toward a molecular design of coupled, yet fully functionals, DTE-based multiswitches.
Co-reporter:Cloé Azarias, Šimon Budzák, Adèle D. Laurent, Gilles Ulrich and Denis Jacquemin
Chemical Science 2016 vol. 7(Issue 6) pp:3763-3774
Publication Date(Web):23 Feb 2016
DOI:10.1039/C5SC04826E
Dyes undergoing excited-state intramolecular proton transfer (ESIPT) are known to present large Stokes shifts as a result of the important geometrical reorganisation following photon absorption. When the ESIPT process is not quantitative, one can obtain dual emitters characterised by two distinct fluorescence bands, observed due to emissions from both the canonical and ESIPT isomers. However, dual emission generally requires to maintain a very specific balance, as the relative excited-state free energies of the two tautomers have to be within a narrow window to observe the phenomenon. Consequently, simple chemical intuition is insufficient to optimise dual emission. In the present contribution, we investigate, with the help of quantum-mechanical tools and more precisely, time-dependent density functional theory (TD-DFT) and algebraic diagrammatic construction (ADC), a wide panel of possible ESIPT/dual emitters with various substituents. The selected protocol is first shown to be very robust on a series of structures with known experimental behaviour, and next is applied to novel derivatives with various substituents located at different positions. This work encompasses the largest chemical library of potential ESIPT compounds studied to date. We pinpoint the most promising combinations for building dual emitters, highlight unexpected combination effects and rationalise the impact of the different auxochromes.
Co-reporter:Kathy J. Chen, Adèle D. Laurent, Florent Boucher, Fabrice Odobel and Denis Jacquemin
Journal of Materials Chemistry A 2016 vol. 4(Issue 6) pp:2217-2227
Publication Date(Web):15 Jan 2016
DOI:10.1039/C5TA10421A
Although copper thiocyanate (CuSCN) shows potential as a substrate for p-type dye sensitised solar cells, its interaction with organic anchoring groups remains largely unexplored. In this ab initio study, we provide atomistic insight into how CuSCN surfaces interact with a series of nitrogen-based (pyridine, aniline, phenanthroline, benzenediamine) and sulfur-based (thiophenol, thiophenoxide, thiocatechol) anchoring groups. We profile several low-index surfaces, including both polar and nonpolar cleavages, to determine their stabilities and electronic structures. In screening these surfaces for the most favourable adsorption modes and binding sites for organic anchors, we found that adsorption is chiefly driven by the propensity of surface copper atoms to restore a tetrahedronal coordination environment. We show that the majority of the tested anchors, even the bidentate structures, exhibit low binding energies on CuSCN, which illustrates how chemical intuition may be misleading for identifying the ideal anchors on the basis of nucleophilicity and denticity alone. By pinpointing the causes of modest adsorption energies, we present hints as to how adsorption strength and alignment of the organic–inorganic states can be improved on CuSCN.
Co-reporter:Julien Boixel, Yifan Zhu, Hubert Le Bozec, Mohamed Ali Benmensour, Abdou Boucekkine, Keith Man-Chung Wong, Alessia Colombo, Dominique Roberto, Véronique Guerchais and Denis Jacquemin
Chemical Communications 2016 vol. 52(Issue 63) pp:9833-9836
Publication Date(Web):13 Jul 2016
DOI:10.1039/C6CC03431D
We disclose two unprecedented complexes built with a central dithienylethene photochrome connecting two cyclometalated Pt(II) moieties either on the reactive carbon atoms or on the lateral non-reactive carbon atoms of the photochrome. The two systems show vastly different properties that are rationalised thanks to quantum-chemical calculations.
Co-reporter:Mohamed Raoui, Julien Massue, Cloé Azarias, Denis Jacquemin and Gilles Ulrich
Chemical Communications 2016 vol. 52(Issue 59) pp:9216-9219
Publication Date(Web):03 Jun 2016
DOI:10.1039/C6CC03745C
The investigation of the optical properties of extended 2-(2-hydroxyphenyl)benzazole dyes showed a complete frustration of the excited-state intramolecular proton transfer (ESIPT) process leading to a novel family of highly fluorescent fluorophores. In the case of a benzothiazole ring, restoration of ESIPT can be observed in acidic medium leading to ratiometric sensing. These experimental results have been rationalised by first-principle calculations.
Co-reporter:Denis Jacquemin
Journal of Chemical Theory and Computation 2016 Volume 12(Issue 8) pp:3993-4003
Publication Date(Web):July 6, 2016
DOI:10.1021/acs.jctc.6b00498
The accuracies of the excited-state dipole and quadrupole moments obtained by TD-DFT are assessed by considering 16 different exchange-correlation functionals and more than 30 medium and large molecules. Except for excited-state presenting a significant charge-transfer character, a relatively limited dependency on the nature of the functional is found. It also turns out that while DFT ground-state dipole moments tend to be too large, the reverse trend is obtained for their excited-state counterparts, at least when hybrid functionals are used. Consequently, the TD-DFT excess dipole moments are often too small, an error that can be fortuitously corrected for charge-transfer transition by selecting a pure or a hybrid functional containing a small share of exact exchange. This error-cancelation phenomena explains the contradictory conclusions obtained in previous investigations. Overall, the largest correlation between CC2 and TD-DFT excess dipoles is obtained with M06-2X, but at the price of a nearly systematic underestimation of this property by ca. 1 D. For the excess quadrupole moments, the average errors are of the order of 0.2–0.6 D·Å for the set of small aromatic systems treated.
Co-reporter:Denis Jacquemin, Ivan Duchemin, Aymeric Blondel, and Xavier Blase
Journal of Chemical Theory and Computation 2016 Volume 12(Issue 8) pp:3969-3981
Publication Date(Web):July 12, 2016
DOI:10.1021/acs.jctc.6b00419
Aiming to assess the accuracy of the oscillator strengths determined at the BSE/GW level, we performed benchmark calculations using three complementary sets of molecules. In the first, we considered ∼80 states in Thiel’s set of compounds and compared the BSE/GW oscillator strengths to recently determined ADC(3/2) and CC3 reference values. The second set includes the oscillator strengths of the low-lying states of 80 medium to large dyes for which we have determined CC2/aug-cc-pVTZ values. The third set contains 30 anthraquinones for which experimental oscillator strengths are available. We find that BSE/GW accurately reproduces the trends for all series with excellent correlation coefficients to the benchmark data and generally very small errors. Indeed, for Thiel’s sets, the BSE/GW values are more accurate (using CC3 references) than both CC2 and ADC(3/2) values on both absolute and relative scales. For all three sets, BSE/GW errors also tend to be nicely spread with almost equal numbers of positive and negative deviations as compared to reference values.
Co-reporter:Antonio Prlj, María Eugenia Sandoval-Salinas, David Casanova, Denis Jacquemin, and Clémence Corminboeuf
Journal of Chemical Theory and Computation 2016 Volume 12(Issue 6) pp:2652-2660
Publication Date(Web):May 4, 2016
DOI:10.1021/acs.jctc.6b00245
The description of low-lying ππ* states of linear acenes by standard electronic structure methods is known to be challenging. Here, we broaden the framework of this problem by considering a set of fused heteroaromatic rings and demonstrate that standard electronic structure methods do not provide a balanced description of the two (typically) lowest singlet state (La and Lb) excitations. While the Lb state is highly sensitive to correlation effects, La suffers from the same drawbacks as charge transfer excitations. We show that the comparison between CIS/CIS(D) can serve as a diagnostic for detecting the two problematic excited states. Standard TD-DFT and even its spin-flip variant lead to inaccurate excitation energies and interstate gaps, with only a double hybrid functional performing somewhat better. The complication inherent to a balanced description of these states is so important that even CC2 and ADC(2) do not necessarily match the ADC(3) reference.
Co-reporter:Šimon Budzák, Adéle D. Laurent, Christian Laurence, Miroslav Medved’, and Denis Jacquemin
Journal of Chemical Theory and Computation 2016 Volume 12(Issue 4) pp:1919-1929
Publication Date(Web):March 11, 2016
DOI:10.1021/acs.jctc.6b00149
4-Nitropyridine N-oxide is a well-known molecular probe for which the experimental UV/vis absorption spectrum has been measured in a large number of solvents. Previous measurements and their analyses suggest a dominant role of the solvent hydrogen-bond donation (HBD) capability in the solvatochromic shifts measured for the absorption spectra. Herein, we analyze these solvatochromic effects using a series of complementary approaches, including empirical solvent parameters, high-level calculation of the excited-state dipole and polarizability, several flavors of the polarizable continuum model, as well as dynamics using an effective fragment potential (EFP) description of the solvent molecules. First, applying a recently proposed set of solvent parameters, we show the importance of dispersion interactions for non-HBD solvents. This statement confronts advanced coupled-cluster and multireference calculations of dipole moments and polarizabilities of both the ground and excited states in gas phase. We further address the pros and cons of implicit solvent models combined to time-dependent density functional theory (TD-DFT) in describing the solvents effects for all (HBD and non-HBD) media, the simplest linear-response approach turning out to be the most adequate. Finally, we show that the explicit TD-DFT/EFP2 models work correctly for HBD molecules and allow for restoration of the main experimental trends.
Co-reporter:Gabriel Marchand, Patrick Giraudeau, Zhongrui Chen, Mourad Elhabiri, Olivier Siri and Denis Jacquemin
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 14) pp:9608-9615
Publication Date(Web):09 Mar 2016
DOI:10.1039/C6CP01275B
Understanding the chemical nature and spectroscopic signatures of a new class of organic molecules remains a strong challenge. Azacalixphyrin, the first member of a family of strongly aromatic macrocycles absorbing in the near infrared domain, can exist in several tautomeric forms. Here, we use DFT calculations and NMR measurements to propose the first in-depth investigation of proton exchanges occurring in two forms of azacalixphyrins (non-protonated and protonated). Our results reveal, on the one hand, a very effective solvent-assisted tautomerism in the non-protonated form whereas the intramolecular proton transfer is less probable, and, on the other hand, the presence of a mixture of almost isoenergetic tautomers differing in both their aromaticity and absorption profiles. This clearly indicates that smartly-designed chemical substitutions could alter the relative weights of the different tautomers, and consequently tune the optical signatures of these new macrocycles in a versatile and efficient way. For the protonated form, rotations of the NH2 groups take place rather than the chemical exchange.
Co-reporter:Arnaud Fihey, Anthony Favennec, Boris Le Guennic and Denis Jacquemin
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 14) pp:9358-9366
Publication Date(Web):23 Oct 2015
DOI:10.1039/C5CP05653E
We investigate with a hybrid SOS-CIS(D)/TD-DFT approach accounting for solvation effects, the structural, electronic and optical properties of recently-proposed PODIPY dyes. Being more soluble in water than the well-known BODIPYs, these new chromogens are particularly appealing, but their characterization remains very limited. It turns out that the selected theoretical protocol could reproduce the experimentally reported differences between PODIPY and BODIPY dyes. Based on this, we have investigated a large number of new PODIPY dyes and determined their theoretical 0–0 energies.
Co-reporter:Lucile Dondaine;Daniel Escudero;Moussa Ali;Philippe Richard;Franck Denat;Ali Bettaieb;Pierre Le Gendre;Catherine Paul;Christine Goze;Ewen Bodio
European Journal of Inorganic Chemistry 2016 Volume 2016( Issue 4) pp:545-553
Publication Date(Web):
DOI:10.1002/ejic.201501304
Abstract
Ten metal-based complexes and associated ligands have been synthesized and characterized. One of the metal ligands is a coumarin-phosphine derivative, which displays tunable fluorescence properties. The fluorescence is quenched in the case of the free ligand and ruthenium and osmium complexes, whereas it is strong for the gold complexes and phosphonium derivatives. These trends were rationalized by theoretical calculations, which revealed non-radiative channels involving a dark state for the free ligands that is lower in energy than the emissive state and is responsible for the quenching of fluorescence. For the RuII and OsII complexes, other non-radiative channels involving the manifold of singlet and triplet excited states may play a role. The anti-proliferative properties of all the compounds were evaluated in cancer cell lines (SW480, HCT116, MDA-MB-231 and MCF-7); higher IC50 values were obtained for gold(I) complexes, with the free ligands being only weakly cytotoxic.
Co-reporter:Shohei Nishizawa, Arnaud Fihey, Denis Jacquemin, Kenji Matsuda
Chemical Physics Letters 2016 Volume 659() pp:258-262
Publication Date(Web):16 August 2016
DOI:10.1016/j.cplett.2016.07.027
Highlights
- •
The exchange interaction J and the first hyperpolarizability β for DAEs were calculated.
- •
The direction of change is always logically related to the π-conjugation pathway.
- •
The switching directions of J and β are different for some DAEs.
- •
The SE values of β are smaller than the SE values of J for all molecules.
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Oxidizing the sulfur atoms of the DAEs yields small variations on SE of J and β.
Co-reporter:José P. Cerón-Carrasco, Denis Jacquemin, Adèle D. Laurent
Computational and Theoretical Chemistry 2016 Volume 1077() pp:58-64
Publication Date(Web):1 February 2016
DOI:10.1016/j.comptc.2015.10.018
•QM/QM′ is used to explore the antioxydant activity of bilverdin embedded into PcyA.•Arg149, Lys221, His88 and water play a pivotal role on the BV stabilization in PcyA.•Antioxidant activity strongly depends on biliverdin conformation and close residues.Phycocyanobilin:Ferredoxin Oxidoreductase (PcyA) is a ferredoxin-dependent bilin reductase that converts biliverdin IXα (BV) into 3Z/3E-phycocyanobilin (3Z/3E-PCB) through a four-electron reduction mechanism. Using state-of-the-art QM and QM/QM′ approaches, we found that the propensity of BV to bind PcyA is dominated by electrostatic interactions, especially related to the Arg149 and the Lys221 residues, while H-bonds are formed with His88 and Ser114. Our simulations also reveal that the antioxidant activity is dependent on the intramolecular non-covalent bond interactions. Indeed, we found that the surrounding residues increase the antioxidant character of BV by 2 eV. In addition, the BV antireductant capacity was investigated for the first time demonstrating that it is much more sensitive to the surrounding residues than its antioxidant counterpart.
Co-reporter:Šimon Budzák, Azzam Charaf-Eddin, Miroslav Medved’, Daniel T. Gryko, Denis Jacquemin
Computational and Theoretical Chemistry 2016 Volume 1076() pp:57-64
Publication Date(Web):15 January 2016
DOI:10.1016/j.comptc.2015.12.001
•The optical spectra of new bis-coumarins is computed.•Several theoretical models are used: TD-DFT, ADC(2) and CC2.•Complex spectral features are analyzed.Using a series of ab initio approaches, we investigate the optical spectra of recently synthesised fluorescent bis-coumarins (Tasior et al., 2014). We show that the complex absorption spectra of several derivatives originate in the overlapping of contributions from energetically-close excited-states. These states have been carefully characterised using TD-DFT, ADC(2) and CC2 levels of theory and accounting for solvent effects using the corrected linear response PCM scheme. We show how such a refined protocol is both necessary and useful to investigate photophysics of these bis-coumarins. In addition to an analysis of the nature of the excited-states of these systems, the vibrationally-resolved spectrum was determined for the parent molecule.
Co-reporter:Yoann Farré
The Journal of Physical Chemistry C 2016 Volume 120(Issue 15) pp:7923-7940
Publication Date(Web):March 14, 2016
DOI:10.1021/acs.jpcc.5b12489
In this study, four new diketopyrrolopyrrole (DPP) sensitizers, with a dicarboxylated triphenylamine anchoring group for attachment to NiO, were prepared and their electronic absorption, emission and electrochemical properties were recorded. The nature of the electronic excited-states was also modeled with Time-Dependent Density Functional Theory (TD-DFT) quantum chemistry calculations. The photovoltaic performances of these new dyes were characterized in NiO-based dye-sensitized solar cells (DSCs) with the classical iodide/triiodide and cobalt(II/III)–polypyridine electrolytes, in which they proved to be quite active. Laser spectroscopy on dye/NiO/electrolyte films gave evidence for ultrafast hole injection into NiO (0.2–10 ps time scales). For the dyes with an appended naphtalenediimide (NDI) acceptor unit, ultrafast electron transfer to the NDI dramatically prolonged the lifetime of the charge separated state NiO+/dye–, from the ps time scale to an average lifetime ≈0.25 ms, which is among the slowest charge recombinations ever reported for dye/NiO systems. This allowed for efficient regeneration by CoIII–polypyridine electrolytes, which translated into much improved PV-performance compared to the DPP dyes without appended NDI. Overall, these results underscore the suitability of DPP as sensitizers for NiO-based photoelectrochemical devices for photovoltaic and photocatalysis.
Co-reporter:Wenbo Yang
The Journal of Physical Chemistry C 2016 Volume 120(Issue 19) pp:10162-10175
Publication Date(Web):April 21, 2016
DOI:10.1021/acs.jpcc.6b01584
Efficient intersystem crossing (ISC) in heavy-atom-free organic chromophores remains rare because of the lack of strong spin–orbit coupling effects in such compounds. Finding organic chromophores with ISC ability is important for applications in several areas, e.g., photocatalysis and photodynamic therapy. Herein, we report new perylenebisimide (PBI) chromophores with tetraphenylethynyl substituents at the 2,5,8,11-positions of the PBI core (ortho-positions, not the usually reported bay-positions of PBI), which show efficient ISC without the presence of any heavy atoms. Steady-state and picosecond–nanosecond transient absorption spectroscopies as well as time-dependent density functional theory computations were used to reveal the photophysical properties. For one of the PBI derivatives, excitation wavelength-dependent ISC was observed. The efficient ISC was attributed to the S1/S2 → Tn (n > 1) processes. Photochemical reduction of the PBI derivatives in the presence of a sacrificial electron donor (triethanolamine) produced a stable PBI radical anion.
Co-reporter:Dr. Adèle D. Laurent;Dr. Miroslav Medve&x10f;; Denis Jacquemin
ChemPhysChem 2016 Volume 17( Issue 12) pp:
Publication Date(Web):
DOI:10.1002/cphc.201600478
Abstract
The front cover artwork is provided by University of Nantes (France) and Matel Bel University in Banská Bystrica (Slovakia). The image shows the vibrationally-resolved spectra of the open DASA isomer. Read the full text of the article at 10.1002/cphc.201600041.
Co-reporter:Dr. Adèle D. Laurent;Dr. Miroslav Medve&x10f;; Denis Jacquemin
ChemPhysChem 2016 Volume 17( Issue 12) pp:
Publication Date(Web):
DOI:10.1002/cphc.201600479
Co-reporter:Anna Maria Grabarz, Adèle D. Laurent, Beata Jędrzejewska, Anna Zakrzewska, Denis Jacquemin, and Borys Ośmiałowski
The Journal of Organic Chemistry 2016 Volume 81(Issue 6) pp:2280-2292
Publication Date(Web):February 19, 2016
DOI:10.1021/acs.joc.5b02691
A series of difluoroboranyls derived from amides carrying a variable π-conjugated spacer between the electron-donating (D) and electron-accepting (A) groups was synthesized and characterized with 1H, 11B, 13C, 15N, and 19F NMR, electronic absorption, fluorescence spectroscopies, and first-principle calculations. The D-to-A distance in the series varied from 1.5 to 4.5 Å, causing bathochromic shifts of both the absorption and fluorescence maxima by more than 120 and 213 nm, respectively. These trends are rationalized by quantum-mechanical calculations that allow for quantification of the charge-transfer distance. Theoretical calculations were also performed to determine the vibronic couplings and thus to reproduce the experimental band shapes.
Co-reporter:Šimon Budzák and Denis Jacquemin
The Journal of Physical Chemistry B 2016 Volume 120(Issue 27) pp:6730-6738
Publication Date(Web):June 9, 2016
DOI:10.1021/acs.jpcb.6b04474
A recently synthesized Schiff base used as a probe for aluminum cations was studied with ab initio models. The primary reason for the lack of fluorescence in aprotic solvents was found to be the presence of an efficient conical intersection (CI) between the ground-states and the first singlet excited-states close to the Franck–Condon geometry. The excited-state pathway leading to this CI is barrierless but implies large amplitude motions, explaining why the fluorescence was observed in frozen acetonitrile matrix. Our calculations suggest that constraining the molecule by impending the rotation around the imino bond enables excited-state intramolecular proton transfer. A similar stiffening mechanism is responsible for the strong fluorescence turn-on after formation of complexes between Al3+ cations and dehydrogenated Schiff base. Finally, the analysis of the possible fluorescence mechanisms in water indicates that the anion of 1 is the likely fluorescence source. Overall, this work allows one to disentangle the various origins of fluorescence switching in a probe.
Co-reporter:Anouar Belhboub, Florent Boucher, and Denis Jacquemin
The Journal of Physical Chemistry C 2016 Volume 120(Issue 32) pp:18281-18288
Publication Date(Web):July 27, 2016
DOI:10.1021/acs.jpcc.6b06447
To explore the optoelectronic properties of spiropyran molecular switches adsorbed onto TiO2 anatase surfaces, we performed a density functional theory (DFT)/time-dependent density functional theory (TD-DFT) study considering the two isomeric forms of the photochromes anchored by both their sides. A comparison between the features of the hybrid and isolated systems is proposed to probe the adsorption effects on both subsystems. This comparison considered, on the one hand, the density of states and the alignment of the energy levels, and, on the other hand, the UV–visible spectra of these systems. We show that several electronic and optical characteristics of the hybrid systems are modulated by the open/closed state of the photochromes. These properties are also modified by the localization of the anchor group on the photochrome.
Co-reporter:Fihey Arnaud and Jacquemin Denis
The Journal of Physical Chemistry C 2016 Volume 120(Issue 20) pp:11140-11150
Publication Date(Web):May 2, 2016
DOI:10.1021/acs.jpcc.6b03324
Dimers of dithienylethenes containing a metallic center in their bridging unit often exhibit a full and stepwise photochromism, and their photoactivity typically surpasses the majority of their metal-free counterparts that are often plagued by the impossibility to switch all units. In this work, we investigate five different photochromic dimers with a relativistic spin–orbit time-dependent density functional theory (SO-TD-DFT) approach and explore the possible sources of this enhanced photoactivity. In particular the potential intersystem crossing (ISC) from an intense singlet state in the UV region to a triplet state presenting the necessary topology to trigger the ring closing of the switch is unravelled in several cases. The efficiency of this crossing is found to be dependent on both the nature of the metallic center and the structure of the dithienylethene ligand but, in general, improves the probability for the second ring closing starting from the partially switched dimer. This work provides the first theoretical evidence of the presence of strong relativistic effects yielding ISC to a “photochromic” triplet state in these complex systems. This allows for the rationalization of several experimental outcomes.
Co-reporter:Dr. Adèle D. Laurent;Dr. Miroslav Medve&x10f;; Denis Jacquemin
ChemPhysChem 2016 Volume 17( Issue 12) pp:1846-1851
Publication Date(Web):
DOI:10.1002/cphc.201600041
Abstract
We present the first theoretical investigation of a recently proposed class of photochromes, namely donor–acceptor Stenhouse adduct (DASA) switches [J. Am. Chem. Soc. 2014, 136, 8169–8172]. By using density functional theory and its time-dependent counterpart, we investigate the ground- and excited-state structures, electronic transition energies, and several properties of the two isomeric forms. In addition to demonstrating that the selected level of theory is able to reproduce the main experimental facts, we show that 1) the two forms of the DASA photochromes are close to isoenergetic; 2) the two isomers possess similar total dipole moments, in spite of their very different sizes; 3) both isomers have a zwitterionic nature; 4) the nature of the dipole-allowed electronic excited state is vastly different in the two forms; and 5) the specific band shape of the extended DASA can be reproduced by vibronic calculations.
Co-reporter:Cloé Azarias and Denis Jacquemin
The Journal of Physical Chemistry A 2016 Volume 120(Issue 18) pp:2824-2831
Publication Date(Web):April 13, 2016
DOI:10.1021/acs.jpca.6b02313
Carbazole–porphyrinoids are [20]porphyrins that can be oxidized to the so-called porphyrin state, inducing a huge shift of the main absorption band from the UV–visible to the infrared region. In this study, we focus on the compound synthesized by Arnold and co-workers [Arnold, L.; Baumgarten, M.; Müllen, K. A. Chem. Commun., 2012, 48, 9640−9642], where the two pyrroline units of a porphyrin are replaced with carbazole moieties. Due to the poor stability of these macrocycles, the nature of the oxidation product could not be definitively ascertained experimentally. In that framework, with the help of ab initio approaches, we investigate the structure, the stability, the aromaticity, and the spectroscopic signatures of both the nonoxidized compound and a series of possible oxidation products. Thanks to vibronic simulations, we obtain insights into the nature of the oxidized macrocycle.
Co-reporter:Roberto Russo, Arnaud Fihey, Benedetta Mennucci, and Denis Jacquemin
The Journal of Physical Chemistry C 2016 Volume 120(Issue 38) pp:21827-21836
Publication Date(Web):August 29, 2016
DOI:10.1021/acs.jpcc.6b07776
We present a quantum-mechanical study of the photoactivity of nanoscale architectures based on dithienylethene (DTE) photochromic molecules grafted onto plasmonic gold or silver nanoparticles (NPs). The effects of the metal NPs are included in each step of the quantum-mechanical description through the polarizable continuum model. By a direct comparison with measured data, we demonstrate that such a multiscale model is able to provide a reliable quantification of the spectroscopic parameters characterizing the photoactivity of the switches as well as their evolution under the influence of the plasmonic effects. In particular, both the calculated enhancement factors describing the modification of the DTE photoreactivity close to the NP and the calculated cyclization/cycloreversion quantum yields accounting for the efficiency of the photochromism are in good agreement with the experimental data. In addition, a better understanding of the photoinduced behavior of such complex nanoscaled photochromic systems is given in terms of a molecular-level description.
Co-reporter:Arnaud Fihey, Aurélie Perrier, Wesley R. Browne and Denis Jacquemin
Chemical Society Reviews 2015 vol. 44(Issue 11) pp:3719-3759
Publication Date(Web):29 Apr 2015
DOI:10.1039/C5CS00137D
Molecular systems encompassing more than one photochromic entity can be used to build highly functional materials, thanks to their potential multi-addressability and/or multi-response properties. Over the last decade, the synthesis and spectroscopic and kinetic characterisation as well as the modeling of a wide range of multiphotochromes have been achieved in a field that is emerging as a distinct branch of photochemistry. In this review, we provide an overview of the available multiphotochromic compounds which use a variety of photoactive building blocks, e.g., diarylethene, azobenzene, spiropyran, naphthopyran or fulgimide derivatives. Their efficiency in terms of multi-responsiveness is discussed and several strategies to circumvent the most common limitation (i.e., the loss of photochromism of one part) are described.
Co-reporter:Boris Le Guennic and Denis Jacquemin
Accounts of Chemical Research 2015 Volume 48(Issue 3) pp:530
Publication Date(Web):February 24, 2015
DOI:10.1021/ar500447q
Cyanine derivatives, named from the Greek word kyanos meaning dark-blue, were discovered more than 150 years ago and remain one of the most widely used classes of organic dyes with contemporary applications in photography (panchromatic emulsions), information storage (CD-R and DVD-R media) and biochemistry (DNA and protein labeling) fields. Cyanine chromogens consist of a charged π-conjugated segment containing an odd number of sp2 carbon atoms with the chain capped at the extremities by two electronegative centers, typically nitrogen or oxygen atoms. Cyanines are characterized by a vanishing bond length alternation indicating nearly equal carbon–carbon bond lengths, as well as a very intense and sharp absorption band presenting a shoulder. This hallmark band undergoes a strong red shift when the chain is extended. This so-called vinyl shift is extremely large (ca. 100 nm for each pair of carbon atoms added in the π-conjugated path), making cyanines ideal building blocks for the design of devices with near-infrared applications. Numerous cyanines also exhibit emission bands with large quantum yields. These exceptional optical properties explain why both canonical cyanines and the corresponding fluoroborates (e.g., boron-dipyrromethene, BODIPY) remain the focus of an ever-growing body of experimental work.In turn, this popularity has stimulated quantum mechanical investigations aiming, on the one hand, at probing the specific electronic nature of cyanine dyes and, on the other hand, at helping to design new dyes. However, the adiabatic approximation to time-dependent density functional theory, the most widespread ab initio model for electronically excited states, fails to accurately reproduce the absorption spectra of cyanine derivatives: it yields a systematic and large underestimation of the experimental wavelengths irrespective of the details of the computational protocol. In contrast, highly correlated wave function approaches provide accurate transition energies for model systems but are hardly applicable to real-life cyanines and BODIPY. This indicates that setting up a computationally tractable theoretical protocol that provides both robust and accurate optical spectra for cyanine-based dyes is a major challenge that has only been taken up lately.In this Account, we compile the most recent advances in the field by considering both compact streptocyanines and large fluoroborates. For the former, we summarize the key results obtained with a large panel of theoretical approaches, allowing us not only to understand the origin of the cyanine challenge but also to pinpoint the schemes presenting the most promising accuracy/effort ratio. For the latter, we show via selected examples how theoretical models can be used to reproduce simultaneously experimental band shapes and transition energies, thus paving the way to an efficient in silico design of new compounds.
Co-reporter:Benjamin Lasorne, Arnaud Fihey, David Mendive-Tapia and Denis Jacquemin
Chemical Science 2015 vol. 6(Issue 10) pp:5695-5702
Publication Date(Web):29 Jun 2015
DOI:10.1039/C5SC01960E
Going from photochromic compounds presenting a single switchable function to multi-addressable photochromic multimers remains an extremely difficult task notably because the interactions of several photochromic units through a linker generally result in a substantial loss of photoactivity. Due to their size and the intrinsic complexity of their electronic structure, coupled photochromes also constitute a fundamental challenge for theoretical chemistry. We present here an effective curve-crossing model that, used in connection with easily accessible ab initio data, allows a first understanding of the difficulty to obtain efficient multiphotochromes. Indeed, we demonstrate that extra crossing points, specific to multiphotochromes, have to be passed to ensure reactivity. In addition, the proposed approach allows the definition of an intuitive tilt criterion that can be used to screen a large number of substitution patterns and hence help in the design of new compounds, an aspect that is also developed here. The compatibility of this tilt criterion with previously proposed static Franck–Condon parameters is discussed as well.
Co-reporter:Arnaud Fihey and Denis Jacquemin
Chemical Science 2015 vol. 6(Issue 6) pp:3495-3504
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5SC00856E
Aiming at designing more efficient multiphotochromes, we investigate with the help of ab initio tools the impact of the substitution on a series of dimers constituted of two dithienylethene (DTE) moieties, strongly coupled to each other through an ethynyl linker. The electronic structure and the optical properties of a large panel of compounds, substituted on different positions by various types of electroactive groups, have been compared with the aim of designing a dyad in which the three possible isomers (open–open, closed–open, closed–closed) can be reached. We show that appending the reactive carbons atoms of the DTE core with electroactive groups on one of the two photochromes allows cyclisation to be induced on a specific moiety, which leads to the formation of the desired closed–open isomer. Substituting the lateral positions of the thiophene rings provides further control of the topology of the frontier molecular orbitals, so that the electronic transition inducing the second ring closure stands out in the spectrum of the intermediate isomer.
Co-reporter:Julien Boixel, Véronique Guerchais, Hubert Le Bozec, Agisilaos Chantzis, Denis Jacquemin, Alessia Colombo, Claudia Dragonetti, Daniele Marinotto and Dominique Roberto
Chemical Communications 2015 vol. 51(Issue 37) pp:7805-7808
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5CC01893E
An unprecedented DTE-based Pt(II) complex, 2(o), which stands as the first example of a sequential double nonlinear optical switch, induced first by protonation and next upon irradiation with UV light is presented.
Co-reporter:Denis Jacquemin, Ivan Duchemin, and Xavier Blase
Journal of Chemical Theory and Computation 2015 Volume 11(Issue 7) pp:3290-3304
Publication Date(Web):June 6, 2015
DOI:10.1021/acs.jctc.5b00304
We perform benchmark calculations of the Bethe–Salpeter vertical excitation energies for the set of 28 molecules constituting the well-known Thiel’s set, complemented by a series of small molecules representative of the dye chemistry field. We show that Bethe–Salpeter calculations based on a molecular orbital energy spectrum obtained with non-self-consistent G0W0 calculations starting from semilocal DFT functionals dramatically underestimate the transition energies. Starting from the popular PBE0 hybrid functional significantly improves the results even though this leads to an average −0.59 eV redshift compared to reference calculations for Thiel’s set. It is shown, however, that a simple self-consistent scheme at the GW level, with an update of the quasiparticle energies, not only leads to a much better agreement with reference values, but also significantly reduces the impact of the starting DFT functional. On average, the Bethe–Salpeter scheme based on self-consistent GW calculations comes close to the best time-dependent DFT calculations with the PBE0 functional with a 0.98 correlation coefficient and a 0.18 (0.25) eV mean absolute deviation compared to TD-PBE0 (theoretical best estimates) with a tendency to be red-shifted. We also observe that TD-DFT and the standard adiabatic Bethe–Salpeter implementation may differ significantly for states implying a large multiple excitation character.
Co-reporter:Benedetta Mennucci, Giovanni Scalmani, and Denis Jacquemin
Journal of Chemical Theory and Computation 2015 Volume 11(Issue 3) pp:847-850
Publication Date(Web):February 23, 2015
DOI:10.1021/acs.jctc.5b00108
In this work we compare the excited-state vibrational patterns computed in gas and condensed phases, the latter being modeled with the Polarizable Continuum Model. For the first time we compare the results of two alternative theoretical approaches that is a standard linear-response approximation and a state-specific description, within the corrected linear-response formulation. Using five test molecules, we show that the point group symmetry of the excited-state geometry might differ with the linear and corrected linear-response models. The vibrational frequencies obtained with the latter model are often rather close to their gas counterparts, whereas the linear-response model tends to overestimate solvation effects. The differences in zero-point vibrational energies between the excited and ground states have also been evaluated, and the impact of the selected solvent model is generally limited for this average parameter.
Co-reporter:Denis Jacquemin, Ivan Duchemin, and Xavier Blase
Journal of Chemical Theory and Computation 2015 Volume 11(Issue 11) pp:5340-5359
Publication Date(Web):September 28, 2015
DOI:10.1021/acs.jctc.5b00619
The 0–0 energies of 80 medium and large molecules have been computed with a large panel of theoretical formalisms. We have used an approach computationally tractable for large molecules, that is, the structural and vibrational parameters are obtained with TD-DFT, the solvent effects are accounted for with the PCM model, whereas the total and transition energies have been determined with TD-DFT and with five wave function approaches accounting for contributions from double excitations, namely, CIS(D), ADC(2), CC2, SCS-CC2, and SOS-CC2, as well as Green’s function based BSE/GW approach. Atomic basis sets including diffuse functions have been systematically applied, and several variations of the PCM have been evaluated. Using solvent corrections obtained with corrected linear-response approach, we found that three schemes, namely, ADC(2), CC2, and BSE/GW allow one to reach a mean absolute deviation smaller than 0.15 eV compared to the measurements, the two former yielding slightly better correlation with experiments than the latter. CIS(D), SCS-CC2, and SOS-CC2 provide significantly larger deviations, though the latter approach delivers highly consistent transition energies. In addition, we show that (i) ADC(2) and CC2 values are extremely close to each other but for systems absorbing at low energies; (ii) the linear-response PCM scheme tends to overestimate solvation effects; and that (iii) the average impact of nonequilibrium correction on 0–0 energies is negligible.
Co-reporter:Gabriel Marchand, Hélène Roy, David Mendive-Tapia and Denis Jacquemin
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 7) pp:5290-5297
Publication Date(Web):08 Jan 2015
DOI:10.1039/C4CP05158K
Using first-principle calculations, we characterize the properties of N-confused porphyrins (NCP), with a focus on the differences between the 2H and 3H tautomers. We find that NCP-3H is almost as strongly aromatic as porphyrin, and about twice as aromatic, i.e., remarkably more stable, than NCP-2H, due to the less efficient π-conjugation in the latter form. The deprotonation of the NH-group at the external side of the inverted ring of NCP-2H, adds a lone pair to the π-system, which restores a strong aromaticity, while methylation has no significant effect. Investigating the impact of solvation using a continuum model, we find quite stable solvation energies with a relative dielectric constant, εr, in the 5–40 range, for both tautomers. NCP-3H presents a slightly lower energy than its NCP-2H counterpart in all solvents. However, the energy differences between the two species are of the order of the error margin of the method, hence too small to discuss the experimentally observed stabilization of NCP-3H in dichloromethane (DCM, a poorly polar solvent) and NCP-2H in N,N-dimethylformamide (DMF, a strongly polar solvent) or to extract the population ratios between the two forms in the different solvents. Therefore, the vibronic absorption spectra are also investigated in an effort to rationalize the complex absorption profiles of these NCP derivatives. We find very distinct spectra for the 2H and 3H forms in DMF and DCM, respectively, each fairly reproducing the experiment. We also find that, in the same solvent, the two species exhibit very different signatures, which allows us to conclude that the 2H and 3H tautomers are largely dominant in DMF and DCM, respectively. Interestingly, the vibrational motions that strongly participate in the shoulder of the Soret band and the multiple maxima of the Q-bands largely differ in the two tautomers.
Co-reporter:Shaomin Ji, Jie Ge, Daniel Escudero, Zhijia Wang, Jianzhang Zhao, and Denis Jacquemin
The Journal of Organic Chemistry 2015 Volume 80(Issue 11) pp:5958-5963
Publication Date(Web):May 5, 2015
DOI:10.1021/acs.joc.5b00691
A thiophene-fused BODIPY chromophore displays a large triplet-state quantum yield (ΦT = 63.7%). In contrast, when the two thienyl moieties are not fused into the BODIPY core, intersystem crossing (ISC) becomes inefficient and ΦT remains low (ΦT = 6.1%). First-principles calculations including spin–orbit coupling (SOC) were performed to quantify the ISC. We found larger SOC and smaller singlet–triplet energy gaps for the thiophene-fused BODIPY derivative. Our results are useful for studies of the photochemistry of organic chromophores.
Co-reporter:Arnaud Fihey; Boris Le Guennic
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 15) pp:3067-3073
Publication Date(Web):July 18, 2015
DOI:10.1021/acs.jpclett.5b01333
Building dimers of organic photochromic compounds paves the way to multifunctional switches, but such architectures often undergo partial photoreactivity only. Combining photochromism of molecules and plasmon resonance of gold nanoparticles (NPs) is known to affect the photochromism of monomers, yet the impact on multimers remains unknown. Here we propose a theoretical study of dimers of dithienylethenes by the mean of a hybrid calculation scheme (discrete-interaction model/quantum mechanics). We aim to assess how the optical properties of multiphotochromes are tuned by the influence of the plasmon resonances. We show that, for a typical chemisorption orientation on the NP, the absorption bands responsible for the photochromism are significantly enhanced for both the doubly open and mixed closed-open isomers of the dyad, hinting that plasmon resonance could be used to boost the generally poor photoactivity of dithienylethene dyads.
Co-reporter:Siwar Chibani, Adèle D. Laurent, Boris Le Guennic, and Denis Jacquemin
The Journal of Physical Chemistry A 2015 Volume 119(Issue 21) pp:5417-5425
Publication Date(Web):December 18, 2014
DOI:10.1021/jp509700c
First-principle simulations aimed at accurately reproducing the excited state properties of a large series of ladder-type π-conjugated organic molecules containing heteroatoms (Si, S, B, O, and N) have been performed. In particular, time-dependent density functional theory (TD-DFT) calculations relying on several global and range-separated hybrid functionals have been carried out in conjunction with three variations of the polarizable continuum model (PCM), namely, the linear-response (LR), corrected linear-response (cLR), and state-specific (SS) approaches. For this series of molecules, similar to many borate derivatives, the cLR-PCM-TD-M06-2X approach can be used to reproduce the auxochromic effects that tune the 0–0 energies. However, TD-DFT yields rather large absolute deviations with respect to the experimental 0–0 energies. These systematic errors can be reduced by more than 0.1 eV when scaled opposite spin-configuration interaction singles with a double correction [SOS-CIS(D)] vertical calculations are combined to the PCM-TD-DFT results. This study demonstrates that such a “hybrid” scheme, where the geometrical and vibrational parameters, as well as the solvation effects, are determined with PCM-TD-DFT, whereas the transition energies are obtained with a wavefunction-based method, offers a useful compromise between accuracy and computational cost.
Co-reporter:Kejing Xu
The Journal of Physical Chemistry C 2015 Volume 119(Issue 42) pp:23801-23812
Publication Date(Web):September 25, 2015
DOI:10.1021/acs.jpcc.5b05325
Activatable triplet–triplet annihilation upconversion was achieved using aminomethyleneanthracene derivatives. The molecular structures of the anthracene derivatives were varied by changing the number of phenyl substituents on the anthracene core (A-1, A-2, and A-3 containing no phenyl and one and two phenyl substituents, respectively). The structural modifications tune the intersystem crossing (ISC), the fluorescence, as well as the distance between the electron donor (amino group) and the fluorophore by using methylene (A-1 and A-2) or a benzyl moiety (A-3) as a linker. Triplet–triplet annihilation upconversion is mainly tuned by photoinduced electron transfer (PET). Hence, the fluorescence of A-1 and A-2 can be switched on by protonation or acetylation of the amino group, whereas A-3 gives persistent strong fluorescence. Determination of the Gibbs free energy changes indicated significantly different PET driving forces for the three compounds. The mechanism of the fluorescence switching was studied with steady state UV–vis absorption, fluorescence emission spectroscopy, nanosecond transient absorption spectroscopy, and ab initio computations. We found that the PET exerts different quenching effects on the singlet and triplet excited states of the anthracene derivatives. The triplet–triplet annihilation upconversion using these compounds as triplet acceptors/emitter was studied as well, and it was found that upconversion can be switched on by inhibition of the PET through acetylation and protonation.
Co-reporter:Kathy J. Chen
The Journal of Physical Chemistry C 2015 Volume 119(Issue 7) pp:3684-3696
Publication Date(Web):January 23, 2015
DOI:10.1021/jp510535p
Because photochromes act as light-induced molecular switches, there is considerable interest in exporting their molecular functionality in the solid state in order to develop photoresponsive materials. In that context, we have carried out a DFT investigation of a series of photochromic derivatives of trans/cis-azobenzene and open/closed-diarylethene adsorbed onto rutile (110) and anatase (101) slabs. By varying the auxochromes and the photochromic state, we examine the trends in the surface–adsorbate interplay in terms of the electronic structure, adsorption geometries, and Bader charge transfer. Using principal components analysis, we demonstrate how the dipole moment of the isolated photochrome in the direction of the anchoring group is the most important predictor of the electronic structure of the adsorbed system. A key point of this paper is to show how the energy levels of the isolated photochrome and bare slab change as a result of adsorption and how first-principles modeling helps to rationalize and predict these trends.
Co-reporter:Julien Boixel ; Véronique Guerchais ; Hubert Le Bozec ; Denis Jacquemin ; Anissa Amar ; Abdou Boucekkine ; Alessia Colombo ; Claudia Dragonetti ; Daniele Marinotto ; Dominique Roberto ; Stefania Righetto ;Roberta De Angelis
Journal of the American Chemical Society 2014 Volume 136(Issue 14) pp:5367-5375
Publication Date(Web):March 17, 2014
DOI:10.1021/ja4131615
Novel photochromic dithienylethene-based platinum(II) complexes (C∧N∧N)Pt(C≡C—DTE—C6H4—D) ((C∧N∧N) = 4,4′-di(n-hexyl)-6-phenyl-2,2′-bipyridine; D = H, NMe2) were prepared and characterized. Their excellent photochromic properties allow the photoinduced switching of their second-order nonlinear optical properties in solution, as measured by the EFISH technique, due to formation of an extended π-conjugated ligand upon suitable electromagnetic radiation. Insights into the electronic structures of the complexes and the nature of their excited states have been obtained by DFT and TD-DFT calculations. These novel Pt(II) complexes were nanoorganized in polymer films which were poled, affording new materials characterized by a good second-order NLO response that can be easily switched, with an excellent NLO contrast. To the best of our knowledge, our compounds allowed designing the very first examples of switchable NLO polymer films based on metal complexes.
Co-reporter:Hassib Audi, Zhongrui Chen, Azzam Charaf-Eddin, Anthony D’Aléo, Gabriel Canard, Denis Jacquemin and Olivier Siri
Chemical Communications 2014 vol. 50(Issue 96) pp:15140-15143
Publication Date(Web):10 Oct 2014
DOI:10.1039/C4CC07353C
Stepwise synthesis of linear nickel complex oligomer tapes with no need for solid-phase support has been achieved. The control of the length in flat arrays allows a fine-tuning of the absorption properties from the UV to the NIR region.
Co-reporter:Nicolas Oger;François LeCallonnec;Eric Fouquet;Erwan LeGrognec;François-Xavier Felpin
Advanced Synthesis & Catalysis 2014 Volume 356( Issue 5) pp:1065-1071
Publication Date(Web):
DOI:10.1002/adsc.201301144
Co-reporter:Siwar Chibani, Adèle D. Laurent, Boris Le Guennic, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 10) pp:4574-4582
Publication Date(Web):August 29, 2014
DOI:10.1021/ct500655k
BODIPY and aza-BODIPY dyes constitute two key families of organic dyes with applications in both materials science and biology. Previous attempts aiming to obtain accurate theoretical estimates of their optical properties, and in particular of their 0–0 energies, have failed. Here, using time-dependent density functional theory (TD-DFT), configuration interaction singles with a double correction [CIS(D)], and its scaled-opposite-spin variant [SOS-CIS(D)], we have determined the 0–0 energies as well as the vibronic shapes of both the absorption and emission bands of a large set of fluoroborates. Indeed, we have selected 47 BODIPY and 4 aza-BODIPY dyes presenting diverse chemical structures. TD-DFT yields a rather large mean signed error between the experimental and theoretical 0–0 energies with a systematic overshooting of the transition energies (by ca. 0.4 eV). This error is reduced to ca. 0.2 [0.1] eV when the TD-DFT 0–0 energies are corrected with vertical CIS(D) [SOS-CIS(D)] energies. For BODIPY and aza-BODIPY dyes, both CIS(D) and SOS-CIS(D) clearly outperform TD-DFT. The present computational protocol allows accurate data to be obtained for the most relevant properties, that is, 0–0 energies and optical band shapes.
Co-reporter:Barry Moore II, Azzam Charaf-Eddin, Aurélien Planchat, Carlo Adamo, Jochen Autschbach, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 10) pp:4599-4608
Publication Date(Web):September 9, 2014
DOI:10.1021/ct500712w
Using a set of 20 organic molecules, we assess the accuracy of both the absorption and emission band shapes obtained by two optimally tuned range-separated hybrid functionals possessing 0% (LC-PBE*) and 25% (LC-PBE0*) of short-range exact exchange as well as by four other hybrid functionals including or not dispersion and long-range corrections (APF-D, PBE0-1/3, SOGGA11-X, and ωB97X-D). The band topologies are compared to experimental data and to previous time-dependent density functional theory calculations. It turns out that both optimally tuned functionals vastly improve the vibronic band shapes obtained with the non-tuned LC-PBE approach but, statistically, do not yield more accurate topologies than standard hybrid functionals. In other words, optimal tuning allows to obtain more accurate excited-state energies without degrading the description of band shapes. In addition, the LC-PBE0* 0–0 energies have been determined for a set of 40 compounds, and it is shown that the results are, on average, less accurate than those obtained by LC-PBE* for the same panel of molecules. The correlation between the optimal range-separation parameters determined for LC-PBE* and LC-PBE0* is discussed as well.
Co-reporter:Paul Boulanger, Siwar Chibani, Boris Le Guennic, Ivan Duchemin, Xavier Blase, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 10) pp:4548-4556
Publication Date(Web):August 19, 2014
DOI:10.1021/ct500552e
We propose to use a blend of methodologies to tackle a challenging case for quantum approaches: the simulation of the optical properties of asymmetric fluoroborate derivatives. Indeed, these dyes, which present a low-lying excited-state exhibiting a cyanine-like nature, are treated not only with the Time-Dependent Density Functional Theory (TD-DFT) method to determine both the structures and vibrational patterns but also with the Bethe–Salpeter approach to compute both the vertical absorption and emission energies. This combination allows us to obtain 0–0 energies with a significantly improved accuracy compared to the “raw” TD-DFT estimates. We also discuss the impact of various declinations of the Polarizable Continuum Model (linear-response, corrected linear-response, and state-specific models) on the obtained accuracy.
Co-reporter:Agisilaos Chantzis, Javier Cerezo, Aurélie Perrier, Fabrizio Santoro, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 9) pp:3944-3957
Publication Date(Web):May 21, 2014
DOI:10.1021/ct500371u
This contribution is an investigation of both the structures and optical properties of a set of 14 diverse, recently synthesized diarylethenes using Time-Dependent Density Functional Theory (TD-DFT) at the ωB97X-D/6-31G(d) level of theory. The linear response (LR) and state-specific (SS) versions of the Polarizable Continuum Model (PCM) have been adopted to account for the bulk solvation effects and their relative performances were critically accessed. It is shown, for the first time in the case of nontrivial diarylethenes, that TD-DFT provides good agreement between the experimental absorption-fluorescence crossing points (AFCPs) and their theoretical counterparts when a robust model accounting for both geometrical relaxation and vibrational corrections is used instead of the vertical approximation. On the other hand, the theoretical estimates for the Stokes shifts based on the vertical transition energies were found to be in disagreement with respect to experiment, prompting us to simulate the absorption/emission vibronic band shapes. It is proved that difficulties associated with the breakdown of the harmonic approximation in Cartesian coordinates exist for the investigated system, and we show how they can be at least partially overcome by means of a vertical approach including Duschinsky effects. Our results provide a valuable basis to rationalize the experimental vibronic structure of both emission and absorption bands and are expected to be a significant asset to the understanding of the optical properties of diarylethene derivatives.
Co-reporter:Siwar Chibani, Adèle D. Laurent, Aymeric Blondel, Benedetta Mennucci, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 5) pp:1848-1851
Publication Date(Web):March 24, 2014
DOI:10.1021/ct5001507
The theoretical determination of excited-state structures remains an active field of research, as these data are hardly accessible by experimental approaches. In this contribution, we investigate excited-state geometries obtained with Time-Dependent Density Functional Theory, using both linear-response and, for the first time, corrected linear-response approaches of the Polarizable Continuum Model. Several chromophores representative of key dye families are used. In most cases, the corrected linear-response approach provides bond distances in between the gas and linear-response data, the latter model providing larger medium-induced structural changes than the corrected linear-response model. However, in a few cases, the solvation effects predicted by the two continuum approaches present opposite directions compared to the gas phase reference.
Co-reporter:Paul Boulanger, Denis Jacquemin, Ivan Duchemin, and Xavier Blase
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 3) pp:1212-1218
Publication Date(Web):February 11, 2014
DOI:10.1021/ct401101u
The accurate prediction of the optical signatures of cyanine derivatives remains an important challenge in theoretical chemistry. Indeed, up to now, only the most expensive quantum chemical methods (CAS-PT2, CC, DMC, etc.) yield consistent and accurate data, impeding the applications on real-life molecules. Here, we investigate the lowest lying singlet excitation energies of increasingly long cyanine dyes within the GW and Bethe–Salpeter Green’s function many-body perturbation theory. Our results are in remarkable agreement with available coupled-cluster (exCC3) data, bringing these two single-reference perturbation techniques within a 0.05 eV maximum discrepancy. By comparison, available TD-DFT calculations with various semilocal, global, or range-separated hybrid functionals, overshoot the transition energies by a typical error of 0.3–0.6 eV. The obtained accuracy is achieved with a parameter-free formalism that offers similar accuracy for metallic or insulating, finite size or extended systems.
Co-reporter:Denis Jacquemin, Barry Moore II, Aurélien Planchat, Carlo Adamo, and Jochen Autschbach
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 4) pp:1677-1685
Publication Date(Web):February 25, 2014
DOI:10.1021/ct5000617
Using a set of 40 conjugated molecules, we assess the performance of an “optimally tuned” range-separated hybrid functional in reproducing the experimental 0–0 energies. The selected protocol accounts for the impact of solvation using a corrected linear-response continuum approach and vibrational corrections through calculations of the zero-point energies of both ground and excited-states and provides basis set converged data thanks to the systematic use of diffuse-containing atomic basis sets at all computational steps. It turns out that an optimally tuned long-range corrected hybrid form of the Perdew–Burke–Ernzerhof functional, LC-PBE*, delivers both the smallest mean absolute error (0.20 eV) and standard deviation (0.15 eV) of all tested approaches, while the obtained correlation (0.93) is large but remains slightly smaller than its M06-2X counterpart (0.95). In addition, the efficiency of two other recently developed exchange-correlation functionals, namely SOGGA11-X and ωB97X-D, has been determined in order to allow more complete comparisons with previously published data.
Co-reporter:Siwar Chibani, Azzam Charaf-Eddin, Benedetta Mennucci, Boris Le Guennic, and Denis Jacquemin
Journal of Chemical Theory and Computation 2014 Volume 10(Issue 2) pp:805-815
Publication Date(Web):January 6, 2014
DOI:10.1021/ct4009848
Dioxaborines dyes, based on the OBO atomic sequence, constitute one promising series of molecules for both organic electronics and bioimaging applications. Using Time-Dependent Density Functional Theory, we have simulated the optical signatures of these fluoroborates. In particular, we have computed the 0–0 energies and shapes of both the absorption and the emission bands. To assess the importance of solvent effects three polarization schemes have been applied within the Polarizable Continuum Model: the linear-response (LR), the corrected linear-response (cLR), and the state-specific (SS). We show that the SS approach is unable to yield consistent chemical trends for these challenging compounds that combine charge-transfer and cyanine characters. On the contrary, LR and cLR are more effective in reproducing chemical trends in OBO dyes. We have applied our computational protocol not only to analyze the signatures of existing dyes but also to design structures with red-shifted absorption and emission bands.
Co-reporter:Julien Warnan, Yann Pellegrin, Errol Blart, Lei Zhang, Allison Brown, Leif Hammarström, Denis Jacquemin, Fabrice Odobel
Dyes and Pigments 2014 Volume 105() pp:174-179
Publication Date(Web):June 2014
DOI:10.1016/j.dyepig.2014.01.026
•A synthetic strategy to introduce an acetylacetone (acac) group onto an aryl moiety.•FT-IR spectroscopy reveals effective binding of the acac group to the NiO surface.•Ultrafast hole injection (<200 fs) into NiO is compatible with acac anchor.•acac is a valuable anchoring group for NiO based photoelectrochemical device.In this article, the viability of the first push–pull (nitrophenyl and hexyl-thiophene as acceptor and donor unit respectively) sensitizer functionalized with acetylacetone (acac) anchoring group was assessed for application in p-type dye sensitized solar cells (NiO-based). An effective synthetic strategy to introduce the acac directly to an aryl moiety was developed. Then, the UV–visible absorption, emission and electrochemical properties of this new sensitizer were determined. FT-IR spectroscopy revealed an effective binding of the acac group to NiO surface while time-dependent density functional theory (TD-DFT) calculations predicted a strong charge-transfer transition with no component of the LUMO centred on the acac. Ultrafast hole injection (<200 fs) from the dye excited state into the valence band (VB) of NiO was experimentally demonstrated by transient absorption spectroscopy studies. It was also shown that excitation of the sensitizer leads to the formation of a twisted intramolecular charge transfer (TICT) state. Finally, the photovoltaic performances of this dye were investigated in NiO based solar cells using the iodide/triiodide electrolyte. We measured promising power conversion efficiencies higher than that of the coumarin C343 benchmark reference albeit with a weaker light harvesting efficiency.Acetylacetone was used for the first time as anchoring group for NiO based p-DSCs and proved to be a promising alternative to carboxylic acid.
Co-reporter:Stéphane Aloïse, Ruan Yibin, Ismail Hamdi, Guy Buntinx, Aurélie Perrier, François Maurel, Denis Jacquemin and Michinori Takeshita
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 48) pp:26762-26768
Publication Date(Web):22 Oct 2014
DOI:10.1039/C4CP03641G
The photophysical properties of a series of dithienylethenes, free or blocked in an ideal photoactive conformation by an alkyl bridge, have been investigated by stationary, ultrafast spectroscopy and state-of-the-art time-dependent density functional theory calculations. Thanks to the clear ultrafast transient signatures corroborating NMR results, we bring strong evidence that the unreactive parallel open form conformer has been efficiently removed by the chain. For the first time, the photophysics of this species, namely an internal conversion of 120 ps is highlighted. In contradiction to the main ideas in the literature, the photocyclization mechanism is rationalized by a direct photocyclization mechanism from the Franck–Condon region passing directly through a conical intersection within ≈100 fs (not few picoseconds) while a competitive mechanism occurs through the relaxed S1 state. Relaxation processes (fluorescence and internal conversion) originating from this relaxed state are sensitive to the length of the blocking chain. Both concomitant pathways are necessary to rationalize: (i) the inverse relationship between emission and cyclization quantum yields and (ii) the non-unity value of the latter for bridged compounds.
Co-reporter:Siwar Chibani, Šimon Budzák, Miroslav Medved', Benedetta Mennucci and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 47) pp:26024-26029
Publication Date(Web):13 Oct 2014
DOI:10.1039/C4CP03919J
We compare the solvatochromic shifts measured experimentally and obtained theoretically for the emission of several substitued fluorophores (indole, benzofurazan, naphthalimide…). Our theoretical protocol relies on time-dependent density functional theory and uses several variations of the polarisable continuum model. In particular, we compare the merits of the linear-response and the corrected linear response approaches, the latter being used for both energetic and structural calculations. It turns out that performing fully-consistent corrected linear response calculations yields the smallest mean signed and absolute errors for the solvatochromic shifts, although optimizing the excited-state structures at the linear-response level only induces limited increase of the average deviations. In contrast, for auxochromic effects, the average errors provided by the two solvation models are very similar.
Co-reporter:Pierre O. Hubin, Adèle D. Laurent, Daniel P. Vercauteren and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 46) pp:25288-25295
Publication Date(Web):30 Sep 2014
DOI:10.1039/C4CP03223C
Thermodynamic and kinetic aspects of excited state intramolecular proton transfer (ESIPT) are investigated in 11 chromophores harboring an intramolecular N–H⋯N hydrogen bond [pyridyl pyrazole, pyridyl pyrrole, azaindole, pyridyl indole, pyrroloquinoline, and an analogue of the Blue Fluorescent Protein (BFP) chromophore] with the help of quantum mechanical calculations. For pyridyl pyrazoles, simulated spectra are used to help the interpretation of experimental ones and the effects of several substituents are investigated. Then it is shown that Time-Dependent Density Functional Theory fails to satisfactorily describe the energetic aspects of ESIPT for the BFP chromophore analogue. Equation-of-Motion Coupled Cluster theory is thus used to reach accurate insights for this challenging case.
Co-reporter:David Mendive-Tapia, Aurélie Perrier, Michael J. Bearpark, Michael A. Robb, Benjamin Lasorne and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 34) pp:18463-18471
Publication Date(Web):18 Jul 2014
DOI:10.1039/C4CP03001J
The photochromic properties of diarylethenes, some of the most studied class of molecular switches, are known to be controlled by non-adiabatic decay at a conical intersection seam. Nevertheless, as their fatigue-reaction mechanism – leading to non-photochromic products – is yet to be understood, we investigate the photo-chemical formation of the so-called by-product isomer using three complementary computational methods (MMVB, CASSCF and CASPT2) on three model systems of increasing complexity. We show that for the ring-opening reaction a transition state on S1(2A) involving bond breaking of the penta-ring leads to a low energy S1(2A)/S0(1A) conical intersection seam, which lies above one of the transition states leading to the by-product isomer on the ground state. Therefore, radiationless decay and subsequent side-product formation can take place explaining the photo-degradation responsible for the by-product generation in diarylethene-type molecules. The effect of dynamic electron correlation and the possible role of inter-system crossing along the penta-ring opening coordinate are discussed as well.
Co-reporter:Adèle D. Laurent, Carlo Adamo and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 28) pp:14334-14356
Publication Date(Web):30 Jan 2014
DOI:10.1039/C3CP55336A
In this perspective, we present an overview of the determination of excited-state properties of “real-life” dyes, and notably of their optical absorption and emission spectra, performed during the last decade with time-dependent density functional theory (TD-DFT). We discuss the results obtained with both vertical and adiabatic (vibronic) approximations, choosing relevant examples for several series of dyes. These examples include reproducing absorption wavelengths of numerous families of coloured molecules, understanding the specific band shape of amino-anthraquinones, optimising the properties of dyes used in solar cells, mimicking the fluorescence wavelengths of fluorescent brighteners and BODIPY dyes, studying optically active biomolecules and photo-induced proton transfer, as well as improving the properties of photochromes.
Co-reporter:Claudine Katan, Paul Savel, Bryan M. Wong, Thierry Roisnel, Vincent Dorcet, Jean-Luc Fillaut and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 19) pp:9064-9073
Publication Date(Web):25 Mar 2014
DOI:10.1039/C4CP00478G
In the continuous quest for improving TD-DFT methodologies as a tool to predict the photophysical features of solvated chromophores, we investigate two model regioisomers based on the 1,2,3-triazole moiety. Starting from their experimental absorption and emission spectra, key energy differences highlighting the main trends between the two isomers are extracted and used to gauge the accuracy of several levels of theory. RI-CC2 and EOM-CCSD calculations allow us to ascertain that the low energy spectra are not linked to double excitations. In a vacuum, none of these methods nor any of the implemented TD-DFT levels of theory, ranging from global hybrids (PBE0, B3LYP) to range-separated functionals without (CAM-B3LYP, ωB97X) or with dispersion corrections (ωB97X-D), are able to capture the key features that differentiate the two chromophores. Accounting for solvent within a specific PCM model allows us to recover experimental trends, but the dramatic changes occurring when moving from toluene to THF and/or when using different PCM approaches (LR, cLR, SS) suggest that this agreement is probably fortuitous. Even if the ωB97X-D functional combined with the SS-PCM scheme leads to quantitative agreement with experiment, TD-DFT results obtained for 1,2,3-triazole based chromophores need to be treated with caution. We also show that the SS-PCM approach may be useful to test current and novel exchange–correlation functionals against the charge transfer failure.
Co-reporter:José Pedro Cerón-Carrasco, Javier Cerezo and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 18) pp:8243-8246
Publication Date(Web):25 Nov 2013
DOI:10.1039/C3CP54518K
DNA is constantly exposed to exogenous agents that randomly damage the genetic code. However, external perturbations might also be used to induce malignant cell death if the mutation processes are controlled. The present communication reports a set of parameters allowing DNA mutation through the use of intense external electric fields. This is a step towards the design of pulsed electric field therapy for genetic diseases.
Co-reporter:Ymène Houari, Azzam Charaf-Eddin, Adèle D. Laurent, Julien Massue, Raymond Ziessel, Gilles Ulrich and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 4) pp:1319-1321
Publication Date(Web):14 Nov 2013
DOI:10.1039/C3CP54703E
The potential energy surfaces of dyes displaying strong excited-state intramolecular proton transfer (ESIPT) are investigated with the help of ab initio tools. It allows us to rationalize the interplay between the excited-state transition free energies and the observed optical signatures.
Co-reporter:Adèle D. Laurent, Ymène Houari, Pedro H. P. R. Carvalho, Brenno A. D. Neto and Denis Jacquemin
RSC Advances 2014 vol. 4(Issue 27) pp:14189-14192
Publication Date(Web):06 Mar 2014
DOI:10.1039/C4RA00991F
Recently, the spectroscopic signatures of amino-substituted benzothiadiazoles were investigated by complementary experimental and theoretical approaches [Neto et al., RSC Adv., 2012, 2, 1524–1532]. It was concluded that these molecules were exhibiting excited-state intramolecular proton transfer. In this communication, we revisit these results using a state-of-the-art time-dependent density functional theory approach which provides a complete explanation to the spectroscopic observations.
Co-reporter:Azzam Charaf-Eddin, Thomas Cauchy, François-Xavier Felpin and Denis Jacquemin
RSC Advances 2014 vol. 4(Issue 98) pp:55466-55472
Publication Date(Web):13 Oct 2014
DOI:10.1039/C4RA10731D
In this work, we illustrate how Time-Dependent Density Functional Theory (TD-DFT), that has become an everyday black-box tool for assessing the nature of electronic excited states, can be used to reach an accurate and thorough analysis of experimental optical spectra for a series of organic molecules recently proposed as building blocks for organic electronic devices. The results that yield insights regarding band shapes and extinction coefficients are shown to provide more relevant information than that obtained by the popular vertical approximation. Cases with several overlapping vibronic bands are also discussed. For the vast majority of treated molecules (10 out of 11) the agreement between the theoretical and experimental 0–0 energies and band topologies are really excellent, paving the way towards more refined theoretical designs of new organic electronic chromophores.
Co-reporter:Azzam Charaf-Eddin, Boris Le Guennic and Denis Jacquemin
RSC Advances 2014 vol. 4(Issue 90) pp:49449-49456
Publication Date(Web):26 Sep 2014
DOI:10.1039/C4RA09494H
We have investigated with first principle approaches the optical signatures of derivatives combining a BODIPY core and cyanine-like side chains. More precisely, we computed the 0–0 energies with a Time-Dependent Density Functional Theory (TD-DFT) procedure systematically including both vibrational and continuum solvent effects. However, despite its refinement, this protocol yields large deviations compared to experimental references. For this reason, we turned towards a mixed protocol where the potential energy surfaces of both the ground and the first electronically excited states are evaluated with TD-DFT whereas the vertical transition energies (both absorption and emission) are determined with the CIS(D)/SOS-CIS(D) approaches, that include a perturbative correction for the double excitations. The pros and cons of such a mixed method are discussed in the framework of these challenging dyes.
Co-reporter:Julien Massue, Karima Benelhadj, Siwar Chibani, Boris Le Guennic, Denis Jacquemin, Pascal Retailleau, Gilles Ulrich, Raymond Ziessel
Tetrahedron Letters 2014 Volume 55(Issue 30) pp:4136-4140
Publication Date(Web):23 July 2014
DOI:10.1016/j.tetlet.2014.06.002
The multi-step synthesis, structural and optical properties of original luminescent borate complexes derived from 2-(2′-hydroxybenzofuran)benzoxazole (HBBO) are reported. Functionalization at position 3 of the benzofuran ring was readily achieved through an electrophilic cyclization key step followed by a Sonogashira cross-coupling reaction. The optical properties of the resulting boron difluoride dyes highlight different photophysical behaviors depending on the nature of the substitution at position 3 of the benzofuran core (tBu-phenylacetylene or NnBu2-phenylacetylene). The NnBu2-phenylacetylene moiety favors a sizeable intramolecular charge transfer as evidenced by a strong solvatochromism; a feature further confirmed by ab initio calculations.
Co-reporter:Denis Jacquemin, Siwar Chibani, Boris Le Guennic, and Benedetta Mennucci
The Journal of Physical Chemistry A 2014 Volume 118(Issue 28) pp:5343-5348
Publication Date(Web):June 24, 2014
DOI:10.1021/jp504591t
In this work, we present time-dependent density functional theory calculations of the excited-state geometries and electronic properties of both model cyanines and BODIPY derivatives, which are particularly challenging dyes for theoretical chemistry. In particular, we focus on environmental effects, using a panel of approaches derived from the polarizable continuum model, including full corrected linear response (cLR) values determined through a very recently developed approach. It turns out that in idealized quasi-linear cyanines, all approaches provide very similar excited-state geometries though linear response (LR), and cLR models yield very different transition energies. For the fluoroborate derivatives, LR apparently overestimates the planarity of the excited-state geometries, and cLR optimizations yield slightly smaller fluorescence energies than LR, making these values closer to experimental references. The computed corrections are however too small to explain (taken alone) the significant theory/experiment discrepancies.
Co-reporter:Šimon Budzák, Miroslav Medved′, Benedetta Mennucci, and Denis Jacquemin
The Journal of Physical Chemistry A 2014 Volume 118(Issue 30) pp:5652-5656
Publication Date(Web):July 11, 2014
DOI:10.1021/jp5057623
Aiming to assess the environmental effects on the dipole moments and polarizabilities of electronically excited-states, we have applied a combined Polarizable Continuum Model/Time-Dependent Density Functional Theory (PCM/TD-DFT) approach on six representative chromophores. For the first time, we compare polarizabilities obtained with gas phase, linear-response and corrected linear response continuum models and we also investigate the relative importance of direct (electronic) and indirect (geometric) environmental contributions for these properties. It is shown that the solvent effects on excited-state polarizabilities tend to be large and can often, but not always, be captured with the computationally efficient linear-response formalism.
Co-reporter:Marcello Gennari, Florent Légalité, Lei Zhang, Yann Pellegrin, Errol Blart, Jérôme Fortage, Allison M. Brown, Alain Deronzier, Marie-Noëlle Collomb, Mohammed Boujtita, Denis Jacquemin, Leif Hammarström, and Fabrice Odobel
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 13) pp:2254-2258
Publication Date(Web):June 10, 2014
DOI:10.1021/jz5009714
Three new cyclometalated iridium complexes were prepared and investigated on nanocrystalline NiO cathodes. Nanosecond transient absorption spectroscopy experiments show they present a surprisingly slow geminate charge recombination upon excitation on NiO, representing thus the first examples of simple sensitizers with such feature. These complexes were used in dye-sensitized solar cells using nanocrystalline NiO film as semiconductor. The long-lived charge separated state of these Ir complexes make them compatible with other redox mediators than I3−/I−, such as a cobalt electrolyte and enable to reach significantly high open circuit voltage.Keywords: cobalt complex; p-type semiconductor; photoelectrocatalysis; photovoltaic; transient absorption spectroscopy;
Co-reporter:Adèle D. Laurent
Science China Chemistry 2014 Volume 57( Issue 10) pp:1363-1368
Publication Date(Web):2014 October
DOI:10.1007/s11426-014-5156-1
Recently, the spectroscopic signatures of a benzoselenadiazole derivative have been investigated in the framework of designing a new ratiometric fluoride sensor (Saravanan et al., Org Lett, 2014, 16: 354–357). It was suggested that this sensor is undergoing excited-state intramolecular proton transfer. In this work, we provide a new look at these experimental data, using a state-of-the-art time-dependent density functional theory approach to mimic the spectroscopic signatures. New insights about the nature of the excited-state processes are obtained.
Co-reporter:Titouan Jaunet-Lahary ; Agisilaos Chantzis ; Kathy J. Chen ; Adèle D. Laurent
The Journal of Physical Chemistry C 2014 Volume 118(Issue 49) pp:28831-28841
Publication Date(Web):November 12, 2014
DOI:10.1021/jp510581m
The present contribution constitutes an extensive density functional theory (DFT) investigation of the nonlinear optical (NLO) properties of a large number of molecules belonging to the azobenzene and azothiophene families of photochromic compounds which can act as NLO switches. Toward the design of systems simultaneously presenting both large total nonlinear response values, βtot, and large contrast, βratio, between the cis and trans isomers, we have focused not only on the monomers but also on azobenzene dimers, the latter containing two N═N bonds along the molecular backbone. After it was established that the inclusion of implicit solvation is not important in drawing qualitative conclusions on the NLO switching ability for the investigated systems, gas-phase calculations have shown that for the asymmetric push–pull azobenzene and azothiophene candidates, the combination of strong donating groups such as NPh2, N(Ph-OMe)2, and N(Ph-NMe2)2 with the dicyanoethene group CH═C(C≡N)2 as an acceptor delivers large βtrans (150–217 × 10–30 esu) and non-negligible βcis (18–55 × 10–30 esu) values as well as substantial contrast, βratio (3.9–8.7). For the investigated double azobenzenes, it is found that, with a careful choice of donor and acceptor groups, the contrast, βratio, can be significantly increased compared to that of the monomers while maintaining large β values that facilitate their detection with standard experimental techniques (e.g., electric-field-induced second-harmonic generation). Our results set the stage on which further theoretical and experimental studies can be based in the search for efficient and versatile NLO switches.
Co-reporter:Xiaoneng Cui, Azzam Charaf-Eddin, Junsi Wang, Boris Le Guennic, Jianzhang Zhao, and Denis Jacquemin
The Journal of Organic Chemistry 2014 Volume 79(Issue 5) pp:2038-2048
Publication Date(Web):February 11, 2014
DOI:10.1021/jo402718e
A series of perylene derivatives are prepared as triplet energy acceptors for triplet–triplet annihilation (TTA) assisted upconversion. The aim is to optimize the energy levels of the T1 and S1 states of the triplet acceptors, so that the prerequisite for TTA (2ET1 > ES1) can be better satisfied, and eventually to increase the upconversion efficiency. Tuning of the energy levels of the excited states of the triplet acceptors is realized either by attaching aryl groups to perylene (via single or triple carbon–carbon bonds), or by assembling a perylene-BODIPY dyad, in which the components present complementary S1 and T1 state energy levels. The S1 state energy levels of the perylene derivatives are generally decreased compared to perylene. The anti-Stokes shift, TTA, and upconversion efficiencies of the new triplet acceptors are improved with respect to the perylene hallmark. For the perylene-BODIPY dyads, the fluorescence emission was substantially quenched in polar solvents. Moreover, we found that extension of the π-conjugation of BODIPY energy donor significantly reduces the energy level of the S1 state. Low S1 state energy level and high T1 state energy level are beneficial for triplet photosensitizers.
Co-reporter:Gabriel Marchand, Adèle D. Laurent, Zhongrui Chen, Olivier Siri, and Denis Jacquemin
The Journal of Physical Chemistry A 2014 Volume 118(Issue 38) pp:8883-8888
Publication Date(Web):August 29, 2014
DOI:10.1021/jp507485e
Azacalixphyrin is a recently synthesized precursor of potentially highly versatile analogues of porphyrins. Surprisingly, this macrocyclic compound is stable to such an extent that it could be exposed to air for months as a solid or for days in solution without detectable changes. However, no rationalization of this specific property has been established yet as the structure/electronic features of this novel compound are still very much unknown. Here, we present an extensive theoretical study on the stability of azacalixphyrin. We use density functional theory to quantify both its aromaticity and its reactivity, or more precisely its lack thereof, with water. In addition, since we find that neutral azacalixphyrin has the ability to capture easily two electrons, we also discuss the results obtained for its dianion. We show that the azacalixphyrin core is strongly aromatic despite the antiaromatic peripheric rings, and we find that all reactions with water are extremely endergonic, hence explaining the stability of azacalixphyrin. Upon reduction, the aromatic signature is reversed as the center becomes antiaromatic while the antiaromatic character of the peripheric rings is either remarkably reduced or completely annihilated. Accordingly, we find that the reactivity of the dianion with water is considerably inhibited.
Co-reporter:Kathy J. Chen ; Adèle D. Laurent
The Journal of Physical Chemistry C 2014 Volume 118(Issue 8) pp:4334-4345
Publication Date(Web):February 3, 2014
DOI:10.1021/jp412071e
In this theoretical first principles study, we systematically investigate the second-order nonlinear optical (NLO) properties of a large panel of dithienylethene (DTE) derivatives in order to identify design strategies toward (i) large absolute first hyperpolarizibilities (βtot) and (ii) large contrasts between the NLO responses of the open and closed forms (βratio). Our results show that applying the traditional push–pull organic chromophore design strategy to individual diarylethenes yielded substantial βtot values (100–180 × 10–30 esu); counterintuitively, however, larger βtot responses did not necessarily correlate with larger contrasts between the closed and open forms (βratio ∼ 4). For the class of inverse-DTE, we observed both smaller NLO responses and a reversal of the usual βtotclosed > βtotopen trend. On the other hand, multiswitchable systems comprising several DTE units were shown to be capable of exhibiting both large βtot (100–500 × 10–30) esu and large βratio > 10 due to the supraadditive contribution of each successive ring cyclization to the βtot of the molecule. These findings pave the way for the rational design of diarylethenes toward NLO applications.
Co-reporter:Kedong Yuan;Dr. Julien Boixel;Dr. Agisilaos Chantzis; Denis Jacquemin ;Dr. Véronique Guerchais;Dr. Henri Doucet
Chemistry - A European Journal 2014 Volume 20( Issue 32) pp:10073-10083
Publication Date(Web):
DOI:10.1002/chem.201402768
Abstract
A series of terarylenes incorporating benzothiophene (BT)/benzofuran (BF) as the central ethene unit was synthesised by using sequential Pd-catalysed CH activation reactions. This new methodology allows the easy modification of the nature of the pendant heteroarene groups. Diaryl ethene (DAE) derivatives with thiophene, thiazole, pyrrole, isoxazole and pyrazole rings were prepared. A large number of asymmetrical DAEs are easily accessible by this new method in both the BT and BF series. The study of their photochromic properties in solution revealed that the nature of the heteroarene and of the central unit drastically modify their photochromic behaviour. TD-DFT calculations were performed to assess the nature of the relevant excited states.
Co-reporter:Karima Benelhadj;Wenziz Muzuzu;Dr. Julien Massue;Dr. Pascal Retailleau;Dr. Azzam Charaf-Eddin;Dr. Adèle D. Laurent; Denis Jacquemin;Dr. Gilles Ulrich;Dr. Raymond Ziessel
Chemistry - A European Journal 2014 Volume 20( Issue 40) pp:12843-12857
Publication Date(Web):
DOI:10.1002/chem.201402717
Abstract
The synthesis, structural, and photophysical properties of a new series of original dyes based on 2-(2′-hydroxybenzofuran)benzoxazole (HBBO) is reported. Upon photoexcitation, these dyes exhibit intense dual fluorescence with contribution from the enol (E*) and the keto (K*) emission, with K* being formed through excited-state intramolecular proton transfer (ESIPT). We show that the ratio of emission intensity E*/K* can be fine-tuned by judiciously decorating the molecular core with electron-donating or -attracting substituents. Push–pull dyes 9 and 10 functionalized by a strong donor (nNBu2) and a strong acceptor group (CF3 and CN, respectively) exhibit intense dual emission, particularly in apolar solvents such as cyclohexane in which the maximum wavelength of the two bands is the more strongly separated. Moreover, all dyes exhibit strong solid-state dual emission in a KBr matrix and polymer films with enhanced quantum yields reaching up to 54 %. A wise selection of substituents led to white emission both in solution and in the solid state. Finally, these experimental results were analyzed by time-dependent density functional theory (TD-DFT) calculations, which confirm that, on the one hand, only E* and K* emission are present (no rotamer) and, on the other hand, the relative free energies of the two tautomers in the excited state guide the ratio of the E*/K* emission intensities.
La synthèse, les études structurales et photophysiques d’une nouvelle série de fluorophore basée sur une architecture 2-(2′-hydroxybenzofuran)benzoxazole (HBBO) sont décrites. Après photoexcitation, ces composés présentent une intense émission duale issue de l’émission simultanée des états excités des formes énol (E*) et kéto (K*). La forme K* est formée après un transfert de proton intramoléculaire dans l’état excité (ESIPT). Nous montrons que le ratio des intensités d’émission E*/K* peut être finement modulé par un choix judicieux de décoration sur le squelette moléculaire avec des substituents fortement donneur ou attracteur. Les colorants push–pull 9 et 10 fonctionnalisés par un donneur fort (nNBu2) sur la partie phénol et un accepteur fort (CF3 et CN respectivement) sur la partie benzoxazole présentent une émission duale intense, et ceci plus particulièrement dans des solvants apolaires tels que le cyclohexane, cas où la séparation entre les deux pics d’émission est la plus importante. Tous ces composés présentent en plus, une importante émission à l’état solide, que ce soit dans une matrice de KBr ou dans un film polymère, avec un rendement quantique de fluorescence allant jusqu’à 54 %. Une sélection pertinente de substituents permet d’obtenir une émission blanche en solution ou à l’état solide. Enfin, ces résultats expérimentaux ont été confirmés par TD-DFT (time-dependent density functional theory); ces études montrent non seulement que seules les émissions des espèces E* et K* sont présentes durant le processus (pas de rotamère), mais aussi que l’énergie libre relative des deux tautomères dans l’état excite guide le ratio des intensités d’émission E*/K*.
Co-reporter:Carlo Adamo and Denis Jacquemin
Chemical Society Reviews 2013 vol. 42(Issue 3) pp:845-856
Publication Date(Web):02 Nov 2012
DOI:10.1039/C2CS35394F
In this tutorial review, we show how Time-Dependent Density Functional Theory (TD-DFT) has become a popular tool for computing the signatures of electronically excited states, and more specifically, the properties directly related to the optical (absorption and emission) spectra of molecules. We discuss the properties that can be obtained with widely available programs as well as how to account for the environmental effects (solvent and surfaces) and present recent applications in these fields. We next expose the transformation of the TD-DFT results into chemically intuitive parameters (colours as well as charge-transfer distances). Eventually, the non-specialised reader will find a series of advices and warnings necessary to perform her/his first TD-DFT calculations.
Co-reporter:Siwar Chibani, Boris Le Guennic, Azzam Charaf-Eddin, Adèle D. Laurent and Denis Jacquemin
Chemical Science 2013 vol. 4(Issue 5) pp:1950-1963
Publication Date(Web):14 Feb 2013
DOI:10.1039/C3SC22265A
BODIPY dyes constitute one of the most efficient class of fluorescent molecules, yet their absorption and emission signatures are hardly predictable with theoretical tools. Here, we use a robust Time-Dependent Density Functional Theory approach that simultaneously accounts for solvent and vibrational effects, in order to simulate the optical properties of a large panel of BODIPY derivatives. In particular, this contribution is focussed on the accurate determination of both the 0–0 energies and vibronic shapes, that allow meaningful comparisons between experimental measurements and theoretical simulations. It turns out that Truhlar's M06-2X functional is well suited for modelling the variations of the 0–0 energies induced by side groups, modifications of the skeleton, stiffening or extension of the π-path. Indeed, while the absolute mean deviation remains quite sizeable, the determination coefficient between experimental and theoretical energies is exceptionally large (R2 = 0.98), highlighting the robustness of the proposed approach. In addition, for most BODIPYs, theory is able to accurately reproduce vibrationally resolved bands. The developed protocol was successfully applied to provide insights for both pH and ion sensors. It also allowed the understanding of the optical behaviours of a series of BODIPY dimers and NIR dyes. This constitutes an unprecedented investigation of several BODIPY dyes both in terms of the number of treated molecules (more than sixty) and of the reliability of the predictions.
Co-reporter:Kedong Yuan, Julien Boixel, Hubert Le Bozec, Abdou Boucekkine, Henri Doucet, Véronique Guerchais and Denis Jacquemin
Chemical Communications 2013 vol. 49(Issue 72) pp:7896-7898
Publication Date(Web):09 Jul 2013
DOI:10.1039/C3CC43754J
The palladium-catalysed direct di-heteroarylation of 1,2-dichloroperfluorocyclohexene with a variety of heteroarenes gives rise in to a new family of 1,2-di(heteroaryl)perfluorocyclohexenes. These derivatives do not exhibit photoreactivity and this unexpected outcome is explained by calculations demonstrating the lack of reactive isomers.
Co-reporter:José Pedro Cerón-Carrasco and Denis Jacquemin
Chemical Communications 2013 vol. 49(Issue 69) pp:7578-7580
Publication Date(Web):14 May 2013
DOI:10.1039/C3CC42593B
Intense electric fields activate the mutagenic mechanism of a single guanine–cytosine base pair. Would they be able to induce a permanent mutation in real DNA? This question is addressed here by modeling a DNA-embedded fragment with state-of-the-art theoretical tools. We show how DNA can, in principle, be mutated if an appropriate electric field is applied.
Co-reporter:Aurélie Perrier, François Maurel, Wesley R. Browne and Denis Jacquemin
Chemical Communications 2013 vol. 49(Issue 39) pp:4247-4249
Publication Date(Web):23 Oct 2012
DOI:10.1039/C2CC37043C
First principle simulations of an extended hexameric molecular switch are reported. The full switching of the system is explained by investigating the nature of the excited states of all possible isomers. A new multi-addressable asymmetric structure is proposed.
Co-reporter:Kassem Beydoun ; Moussa Zaarour ; J. A. Gareth Williams ; Thierry Roisnel ; Vincent Dorcet ; Aurélien Planchat ; Abdou Boucekkine ; Denis Jacquemin ||; Henri Doucet ;Véronique Guerchais
Inorganic Chemistry 2013 Volume 52(Issue 21) pp:12416-12428
Publication Date(Web):October 14, 2013
DOI:10.1021/ic401208p
We report the palladium-catalyzed direct 5-arylation of both metalated and nonmetalated thiophene moieties of iridium complexes 2, 3, and 4 with aryl halides via C–H bond functionalization. This method opens new routes to varieties of Ir complexes in only one step, allowing easy modification of the nature of the ligand. The photophysical properties of the new functionalized complexes have been studied by means of absorption and emission spectroscopy. The extension of the π-conjugated system induces a bathochromic and hyperchromic shift of the absorption spectra, an effect reproduced by first principle calculations. Indeed, the bathochromic shifts are related to a more delocalized nature of the excited-states. All complexes are photoluminescent in the red region of the spectrum. This study establishes that arylation of the thienyl ring affects strongly the electronic properties of the resulting complexes, even when the thienyl ring is remote and not directly metalated to the iridium center, as in the thienyltrifluoroacetonate complex 4.
Co-reporter:Agisilaos Chantzis, Adèle D. Laurent, Carlo Adamo, and Denis Jacquemin
Journal of Chemical Theory and Computation 2013 Volume 9(Issue 10) pp:4517-4525
Publication Date(Web):August 21, 2013
DOI:10.1021/ct400597f
The reliability of the Tamm–Dancoff approximation (TDA) for predicting vibrationally resolved absorption and emission spectra of several prototypical conjugated molecules has been addressed by performing a series of extensive theoretical calculations. To this end, we have systematically compared the TDA results with the full Time-Dependent Density Functional Theory (TDDFT), the Random Phase Approximation (RPA), as well as the Configuration Interaction Singles (CIS) methods that are routinely employed for the prediction of optical spectra of large molecules. Comparisons have been made with experimental results for both the band shapes and 0–0 energies. They revealed that TDA is generally able to reproduce the experimental band shapes along with the positions of the absorption and emission peaks. With respect to TDDFT, TDA leads to an underestimation of the relative intensities for most cases but does not alter any other feature of the spectra. For the case of 0–0 energies, it leads to a better agreement between theory and experiment compared to TDDFT for the majority of the molecules studied, at least when combined with the popular B3LYP functional.
Co-reporter:Azzam Charaf-Eddin, Aurélien Planchat, Benedetta Mennucci, Carlo Adamo, and Denis Jacquemin
Journal of Chemical Theory and Computation 2013 Volume 9(Issue 6) pp:2749-2760
Publication Date(Web):April 29, 2013
DOI:10.1021/ct4000795
The band shapes corresponding to both the absorption and emission spectra of a set of 20 representative conjugated molecules, including recently synthesized structures, have been simulated with a Time-Dependent Density Functional Theory model including diffuse atomic orbitals and accounting for bulk solvent effects. Six hybrid functionals, including two range-separated hybrids (B3LYP, PBE0, M06, M06-2X, CAM-B3LYP, and LC-PBE) have been assessed in light of the experimental band shapes obtained for these conjugated compounds. Basis set and integration grid effects have also been evaluated. It turned out that all tested functionals but LC-PBE reproduce the main experimental features for both absorption and fluorescence, though the average errors are significantly larger for the latter phenomena. No single functional stands out as the most accurate for all aspects, but B3LYP yields the smallest mean absolute deviation. On the other hand, M06-2X could be a valuable compromise for excited-states as it reproduces the 0–0 energies and also gives reasonable band shapes. The typical mean absolute deviations between the relative positions of the experimental and theoretical peaks in the vibrationally resolved spectra are ca. 100 cm–1 for absorption and 250 cm–1 for emission. In the same time, the relative intensities of the different maxima are reproduced by TD-DFT with a ca. 10–15% accuracy.
Co-reporter:Siwar Chibani, Azzam Charaf-Eddin, Boris Le Guennic, and Denis Jacquemin
Journal of Chemical Theory and Computation 2013 Volume 9(Issue 7) pp:3127-3135
Publication Date(Web):June 14, 2013
DOI:10.1021/ct400392r
The simulations of excited-state properties, that is, the 0–0 energies and vibronic shapes, of a large panel of fluorophores presenting a NBO atomic sequence have been achieved with a Time-Dependent Density Functional Theory (TD-DFT) approach. We have combined eight hybrid exchange-correlation functionals (B3LYP, PBE0, M06, BMK, M06-2X, CAM-B3LYP, ωB97X-D, and ωB97) to the linear-response (LR) and the state specific (SS) Polarizable Continuum Model (PCM) methods in both their equilibrium (eq) and nonequilibrium (neq) limits. We show that the combination of the SS-PCM scheme to a functional incorporating a low amount of exact exchange can yield unphysical values for molecules presenting large increase of their dipole moments upon excitation. We therefore apply a functional possessing a large exact exchange ratio to simulate the properties of NBO dyes, including large dyads.
Co-reporter:José Pédro Céron-Carrasco, Aymeric Siard, Denis Jacquemin
Dyes and Pigments 2013 Volume 99(Issue 3) pp:972-978
Publication Date(Web):December 2013
DOI:10.1016/j.dyepig.2013.08.006
•Thienopyrazines are studied with theoretical tools.•The protocol reproduces both geometries and absorption spectra.•New very low-gap structures are designed.•One can independently control charge-transfer strength and transition energy.The structural and electronic properties of thieno[3,4-b]pyrazine derivatives have been investigated with a Time-Dependent Density Functional Theory approach accounting for both solvent and long-range Coulombic effects. Using the selected protocol we could accurately reproduce the experimental geometrical parameters as well as the measured optical signatures, the latter including both local and charge-transfer transitions. New structures presenting optimized properties are designed and it is shown that compact structures based on the thieno[3,4-b]pyrazine core might present easily tunable transition energies, opening the door to new very low band-gap oligomers and systems with strong charge-transfer features. We also demonstrate that the absorption energies and charge-transfer strengths can be optimized independently for thieno[3,4-b]pyrazines.
Co-reporter:Boris Le Guennic, Siwar Chibani, Azzam Charaf-Eddin, Julien Massue, Raymond Ziessel, Gilles Ulrich and Denis Jacquemin
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 20) pp:7534-7540
Publication Date(Web):21 Mar 2013
DOI:10.1039/C3CP50669J
The optical properties of a series of recently synthesized [Chem. Eur. J., 2013, DOI: 10.1002/chem.201203625] fluorescent borate complexes based on the 2-(2′-hydroxyphenyl)benzoxazole (HBO) core have been modeled using Time-Dependent Density Functional Theory. The computations use a range-separated hybrid functional (ωB97X-D) and include vertical, adiabatic and vibronic simulations, as well as analysis of the charge-transfer characteristics of each state. This work allows us to interpret the major experimental features, including unexpected evolution of the λmax, band shapes and protonation effects. Two dyads, one including a BODIPY core, have also been tackled.
Co-reporter:Fréderic B. Anne, Florent D. Purpan, Denis Jacquemin
Chemical Physics Letters 2013 Volume 581() pp:52-56
Publication Date(Web):21 August 2013
DOI:10.1016/j.cplett.2013.07.021
•The charge-transfer properties of push–pull oligoenes are modeled.•The charge-transfer distance maximum is obtained for large systems.•The largest density variations are located on the center of the chains.•The push and pull groups are found to have cooperative but not additive effects.We used a TD-DFT approach relying on range-separated hybrids to evaluate the photon induced charge-transfer of substituted polyene oligomers of increasingly long chains. Several exchange–correlation functionals have been considered. Push, pull and push–pull systems containing up to 20 unit cells have been compared. A cooperative, but non additive, impact of the donor and acceptor groups is found. In long oligomers, the changes in the electronic density are mainly located on the central segment and not on the terminal electroactive groups, but the charge-transfer distance remains large, which contrasts with most push–pull compounds.
Co-reporter:José P. Cerón-Carrasco, Mathieu Fanuel, Azzam Charaf-Eddin, Denis Jacquemin
Chemical Physics Letters 2013 Volume 556() pp:122-126
Publication Date(Web):29 January 2013
DOI:10.1016/j.cplett.2012.11.075
Using time-dependent density functional theory, we investigate the solvatochromic effects on the optical spectra of a typical hydroxy coumarin, considering its enol, keto, anionic and cationic forms. The absorption and fluorescence transitions energies have been computed within both the linear-response (LR) and the more refined state specific (SS) approaches, with explicit solvent molecules. These energies have also been used to compute 0–0 transitions and vibrationally resolved spectra. We show that the SS approach is mandatory to describe the solvent response due to the large increase of dipole moment upon the excitation while hydrogen bonds tune both absorption and emission energies.Graphical abstractHighlights► The optical spectra of coumarins is computed with the TD-DFT approach. ► Bulk solvent effect are accounted for by using a state-specific model. ► A hybrid discrete/continuum model is also used to simulate the spectra in water. ► Our results confirm that there is an interplay between implicit and explicit solvent effects in coumarins optical signatures.
Co-reporter:Ymène Houari ; Adèle D. Laurent
The Journal of Physical Chemistry C 2013 Volume 117(Issue 42) pp:21682-21691
Publication Date(Web):September 24, 2013
DOI:10.1021/jp407104m
Perylene diimides and related compounds (naphthalene diimides, anthracene diimides, etc.) are one of the most important classes of organic dyes. Therefore, the prediction and the rationalization of both their transition energies and the particular shape of their absorption and emission spectra is essential to improve their design. Here, we report the simulations of both adiabatic and vibronic signatures of a series of perylene diimide derivatives with a state-of-the-art time-dependent density functional theory (TD-DFT) approach. First, the 0–0 energies have been computed and compared to experimental data. In a second stage, the determination of vibronic shapes has been performed to shed light on the vibrational modes implied in the experimental band topologies. Both anharmonicity and functionnal effects are also discussed. It turns out that theory consistently reproduced 0–0 energies but does not always yield band shapes in perfect match with experiment. In a last stage, new structures are designed, and it is shown that a full push effect is more effective than a push–pull strategy for the present class of molecules.
Co-reporter:Julien Warnan, Victoire-Marie Guerin, Frédéric B. Anne, Yann Pellegrin, Errol Blart, Denis Jacquemin, Thierry Pauporté, and Fabrice Odobel
The Journal of Physical Chemistry C 2013 Volume 117(Issue 17) pp:8652-8660
Publication Date(Web):April 4, 2013
DOI:10.1021/jp402608u
A new ruthenium sensitizer Ru-acac (cis-bis(thiocyanato)(2,2′-bipyridyl-4,4′-di(3-pentane-2,4-dione)(4,4′-dinonyl-2′-bipyridyl)ruthenium(II)) functionalized by acetylacetone (acac) anchoring groups was synthesized and studied in ZnO-based dye-sensitized solar cells (DSCs). In comparison with the parent ruthenium complex bearing classical carboxylic acid groups (coded Z907), Ru-acac exhibits blue-shifted metal-to-ligand charge transfer (MLCT) absorption and emission bands as well as a cathodic shifted oxidation potential (E(RuIII/II)). Quantum chemistry time-dependent density functional theory (TD-DFT) calculations revealed that the acac groups are less conjugated with the pyridine units than carboxylic acid groups, entailing a lower electronic coupling with the semiconductor (SC) conduction band. Finally, the photovoltaic performances of both ruthenium complexes were investigated in DSCs by recording the J/V characteristics under solar spectrum simulation (AM1.5), the photoaction spectra, and by electrochemical impedance measurements. We showed that Z907 display higher photoconversion efficiency than Ru-acac owing to a lower electronic coupling with the SC and a different bending of the conduction band. Interestingly, the acac group provides a covalent binding to the ZnO surface but does not etch the structure as carboxylic acid usually does.
Co-reporter:Aurélie Perrier, Stéphane Aloise, Massimo Olivucci, and Denis Jacquemin
The Journal of Physical Chemistry Letters 2013 Volume 4(Issue 13) pp:2190-2196
Publication Date(Web):June 19, 2013
DOI:10.1021/jz401009b
The understanding of the intimate electronic processes in photochromes is essential to optimize the properties of light-controllable devices. For one of the most studied classes of molecular switches, namely, dithienylethenes, the relative efficiencies of the normal and inverse structures remained puzzling. Indeed, despite a larger ratio of the active antiparallel conformers for the latter, the quantum yields of cyclization of inverse dithienylethenes do not exceed those of its normal counterpart. In the present contribution, we provide the first explanation of this experimental outcome using multireference ab initio quantum chemistry. We demonstrate the existence of a fluorescent intermediate on the S1 state of the inverse system that generates a photochemically unreactive conformation in the ground state. This study paves the way toward a rational development of efficient molecular photochromes presenting a photon-quantitative response.Keywords: conical intersection; diarylethenes; photochromic reaction paths; photochromism; potential energy surfaces;
Co-reporter:Zhongrui Chen;Dr. Michel Giorgi; Denis Jacquemin;Dr. Mourad Elhabiri;Dr. Olivier Siri
Angewandte Chemie International Edition 2013 Volume 52( Issue 24) pp:6250-6254
Publication Date(Web):
DOI:10.1002/anie.201301217
Co-reporter:Zhongrui Chen;Dr. Michel Giorgi; Denis Jacquemin;Dr. Mourad Elhabiri;Dr. Olivier Siri
Angewandte Chemie International Edition 2013 Volume 52( Issue 24) pp:
Publication Date(Web):
DOI:10.1002/anie.201303670
Co-reporter:Zhongrui Chen;Dr. Michel Giorgi; Denis Jacquemin;Dr. Mourad Elhabiri;Dr. Olivier Siri
Angewandte Chemie 2013 Volume 125( Issue 24) pp:6370-6374
Publication Date(Web):
DOI:10.1002/ange.201301217
Co-reporter:Zhongrui Chen;Dr. Michel Giorgi; Denis Jacquemin;Dr. Mourad Elhabiri;Dr. Olivier Siri
Angewandte Chemie 2013 Volume 125( Issue 24) pp:
Publication Date(Web):
DOI:10.1002/ange.201303670
Co-reporter:Dr. Lucie Ordronneau;Dr. Vincent Aubert;Dr. Véronique Guerchais; Abdou Boucekkine;Dr. Hubert LeBozec;Dr. Anu Singh; Isabelle Ledoux; Denis Jacquemin
Chemistry - A European Journal 2013 Volume 19( Issue 19) pp:5845-5849
Publication Date(Web):
DOI:10.1002/chem.201300517
Co-reporter:Dr. Lucie Ordronneau;Dr. Vincent Aubert;Dr. Véronique Guerchais; Abdou Boucekkine;Dr. Hubert LeBozec;Dr. Anu Singh; Isabelle Ledoux; Denis Jacquemin
Chemistry - A European Journal 2013 Volume 19( Issue 19) pp:
Publication Date(Web):
DOI:10.1002/chem.201390068
Co-reporter:Aurélie Perrier, François Maurel, and Denis Jacquemin
Accounts of Chemical Research 2012 Volume 45(Issue 8) pp:1173
Publication Date(Web):June 5, 2012
DOI:10.1021/ar200214k
In single photochromes, the two isomers that are interconverted in photoinduced reactions can serve as on and off states in a molecular switching device. The addition of several photochromic moieties onto a single molecule can allow the processing of more complex logical patterns. For example, an asymmetric triad could, in principle, store a byte, rather than a bit, of data. Because of the potential impact of multiphotochromic molecules in many research areas, over the past decade several groups have synthesized these coupled structures. The targets are easily addressable molecules that display increased contrast between the on and off states and in which all isomers have significantly distinguishable optical signatures.In this Account, we provide an overview of the multiswitchable molecular systems that incorporate at least one diarylethene group, which is the most successful thermally stable (P-type) organic photochrome. Up to this point, most systems have presented significant limitations. First of all, the reversibility of the processes is hindered by several side reactions more frequently than for single photochromes. Second, switching one part of the compound impedes the photoreactivity of other fragments in approximately 50% of the cases, and maximizing the electronic communication increases the probability of partial activity. In addition, most of the few synthesized operative systems only demonstrate cumulative absorption spectra rather than new features. Finally, it is impossible to selectively induce a chosen conversion because one wavelength might trigger several processes. We also emphasize the promising successes of asymmetric diarylethene dimers and trimers and molecules that combine two families of photochromes, such as diarylethene added to fulgimide or phenoxy-naphthacenequinone.In that framework, theoretical simulations offer complementary tools to investigate these structures, both to obtain structure/property relationships and to propose paths for the design of more efficient molecules. However, due to the size of the systems, researchers can only apply semiquantitative models. The investigation of the absorption spectra of the photochromes with time-dependent density functional theory (TD-DFT), the analysis of the topology of the LUMO + n (typically n = 1) of the closed–open hybrid, and an estimate of the steric stress in the hypothetical (ground-state) closed–closed structure serve as a useful combination of parameters to obtain initial insights regarding the photocyclization of the different open diarylethene groups. Nevertheless, because a first-order qualitative approach does not explore the potential energy surface of the photoexcited states, it remains inadequate for the investigation of some molecules.
Co-reporter:Hiroyuki Nitadori, Lucie Ordronneau, Julien Boixel, Denis Jacquemin, Abdou Boucekkine, Anu Singh, Munetaka Akita, Isabelle Ledoux, Véronique Guerchais and Hubert Le Bozec
Chemical Communications 2012 vol. 48(Issue 84) pp:10395-10397
Publication Date(Web):31 Aug 2012
DOI:10.1039/C2CC34999J
The modulation of the quadratic NLO response of an octupolar metal-based chromophore featuring four photochromic dithienylethene units is reported. Quantum mechanical simulations are consistent with a full switching of the DTE units and reproduce the strong enhancement of the NLO response.
Co-reporter:Erik Göransson, Julien Boixel, Jérôme Fortage, Denis Jacquemin, Hans-Christian Becker, Errol Blart, Leif Hammarström, and Fabrice Odobel
Inorganic Chemistry 2012 Volume 51(Issue 21) pp:11500-11512
Publication Date(Web):October 10, 2012
DOI:10.1021/ic3013552
In the context of long-range electron transfer for solar energy conversion, we present the synthesis, photophysical, and computational characterization of two new zinc(II) phthalocyanine oligophenylene-ethynylene based donor-bride-acceptor dyads: ZnPc-OPE-AuP+ and ZnPc-OPE-C60. A gold(III) porphyrin and a fullerene has been used as electron accepting moieties, and the results have been compared to a previously reported dyad with a tin(IV) dichloride porphyrin as the electron acceptor (Fortage et al. Chem. Commun.2007, 4629). The results for ZnPc-OPE-AuP+ indicate a remarkably strong electronic coupling over a distance of more than 3 nm. The electronic coupling is manifested in both the absorption spectrum and an ultrafast rate for photoinduced electron transfer (kPET = 1.0 × 1012 s–1). The charge-shifted state in ZnPc-OPE-AuP+ recombines with a relatively low rate (kBET = 1.0 × 109 s–1). In contrast, the rate for charge transfer in the other dyad, ZnPc-OPE-C60, is relatively slow (kPET = 1.1 × 109 s–1), while the recombination is very fast (kBET ≈ 5 × 1010 s–1). TD-DFT calculations support the hypothesis that the long-lived charge-shifted state of ZnPc-OPE-AuP+ is due to relaxation of the reduced gold porphyrin from a porphyrin ring based reduction to a gold centered reduction. This is in contrast to the faster recombination in the tin(IV) porphyrin based system (kBET = 1.2 × 1010 s–1), where the excess electron is instead delocalized over the porphyrin ring.
Co-reporter:Siwar Chibani, Boris Le Guennic, Azzam Charaf-Eddin, Olivier Maury, Chantal Andraud, and Denis Jacquemin
Journal of Chemical Theory and Computation 2012 Volume 8(Issue 9) pp:3303-3313
Publication Date(Web):August 9, 2012
DOI:10.1021/ct300618j
We have simulated the optical properties of Aza-Boron-dipyrromethene (Aza-BODIPY) dyes and, more precisely, the 0–0 energies as well as the shape of both absorption and fluorescence bands, thanks to the computation of vibronic couplings. To this end, time-dependent density functional theory (TD-DFT) calculations have been carried out with a systematic account of both vibrational and solvent effects. In a first step, we assessed different atomic basis sets, a panel of global and range-separated hybrid functionals as well as different solvent models (linear-response, corrected linear-response, and state-specific). In this way, we have defined an accurate yet efficient protocol for these dyes. In a second stage, several simulations have been carried out to investigate acidochromic and complexation effects, as well as the impact of side groups on the topology of the optical bands. In each case, theory is able to accurately reproduce experimental results and the proposed protocol is consequently useful to design new dyes featuring improved properties.
Co-reporter:Denis Jacquemin, Aurélien Planchat, Carlo Adamo, and Benedetta Mennucci
Journal of Chemical Theory and Computation 2012 Volume 8(Issue 7) pp:2359-2372
Publication Date(Web):June 4, 2012
DOI:10.1021/ct300326f
Using TD-DFT, we performed simulations of the adiabatic energies of 40 fluorescent molecules for which the experimental 0–0 energies in condensed phase are available. We used six hybrid functionals (B3LYP, PBE0, M06, M06-2X, CAM-B3LYP, and LC-PBE) that have been shown to provide accurate transition energies in previous TD-DFT assessments, selected two diffuse-containing basis sets, and applied the most recent models for estimating bulk solvation effects. In each case, the correction arising from the difference of zero-point vibrational energies between the ground and the excited states has been consistently determined. Basis set effects have also been carefully studied. It turned out that PBE0 and M06 are the most effective functionals in terms of average deviation (mean absolute error of 0.22–0.23 eV). However, both the M06-2X global hybrid that contains more exact exchange and the CAM-B3LYP range-separated hybrid significantly improve the consistency of the prediction for a relatively negligible degradation of the average error. In addition, we assessed (1) the cross-structure/spectra relationships, (2) the importance of solvent effects, and (3) the differences between adiabatic and vertical energies.
Co-reporter:José P. Cerón-Carrasco, Alexis Ripoche, Fabrice Odobel, Denis Jacquemin
Dyes and Pigments 2012 Volume 92(Issue 3) pp:1144-1152
Publication Date(Web):March 2012
DOI:10.1016/j.dyepig.2011.07.016
Using ab initio theoretical tools simultaneously accounting for electron correlation and environmental effects, we have simulated the optical spectra of benzodifuranone dyes. In a first step, a valuable computational protocol has been defined and it turned out that a PCM-TD-M06-2X/6-311+G(2d,p)//PCM-PBE0/6-311G(d,p) approach provides an adequate balance between computational requirements and accuracy (deviations of ca. 10 nm with respect to experiment). In a second stage, we have calculated the spectrum of a large series of push-pull structures, and it turned out that the benzodifuranone core is a strong electron capturing group at the excited-state. Indeed, strong auxochroms like the nitro and cyano groups fall short to significantly perturb the LUMO of this series of chromogens. Eventually, in a last phase, the implications of these results are discussed for a series of organic dyes of potential interest for solar cells (DSSC).Highlights► TD-DFT is used to probe the excited-states of benzodifuranone derivatives. ► These dyes act as super-acceptors at the excited-state (very stable LUMO). ► Simulations have been performed for a series of new compounds.
Co-reporter:José P. Cerón-Carrasco, Denis Jacquemin and Emilie Cauët
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 36) pp:12457-12464
Publication Date(Web):23 Mar 2012
DOI:10.1039/C2CP40515F
We investigate possible mutations in the genetic code induced by cisplatin with an approach combining molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. Specifically, the impact of platination on the natural tautomeric equilibrium in guanine–cytosine (GC) base pairs is assessed to disclose the possible role played by non-canonical forms in anti-tumour activity. To obtain valuable predictions, the main interactions present in a real DNA environment, namely hydration and stacking, are simultaneously taken into account. According to our results, the Pt–DNA adduct promotes a single proton transfer reaction in GC in the DNA sequence AC. Such rare tautomers might play an important role in the cisplatin biological activity since they meet the stability requirements necessary to promote a permanent mutation.
Co-reporter:Denis Jacquemin, Tangui Le Bahers, Carlo Adamo and Ilaria Ciofini
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 16) pp:5383-5388
Publication Date(Web):24 Feb 2012
DOI:10.1039/C2CP40261K
We investigate the efficiency of several partial atomic charge models (Mulliken, Hirshfeld, Bader, Natural, Merz–Kollman and ChelpG) for investigating the through-space charge-transfer in push–pull organic compounds with Time-Dependent Density Functional Theory approaches. The results of these models are compared to benchmark values obtained by determining the difference of total densities between the ground and excited states. Both model push–pull oligomers and two classes of “real-life” organic dyes (indoline and diketopyrrolopyrrole) used as sensitisers in solar cell applications have been considered. Though the difference of dipole moments between the ground and excited states is reproduced by most approaches, no atomic charge model is fully satisfactory for reproducing the distance and amount of charge transferred that are provided by the density picture. Overall, the partitioning schemes fitting the electrostatic potential (e.g. Merz–Kollman) stand as the most consistent compromises in the framework of simulating through-space charge-transfer, whereas the other models tend to yield qualitatively inconsistent values.
Co-reporter:Boris Le Guennic, Olivier Maury and Denis Jacquemin
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 1) pp:157-164
Publication Date(Web):08 Nov 2011
DOI:10.1039/C1CP22396H
The excited-state energies of aza-boron-dipyrromethene (Aza-BODIPY) derivatives are investigated with Time-Dependent Density Functional Theory (TD-DFT), with twin goals. On the one hand, a pragmatic, yet efficient, computational protocol is defined in order to reach rapidly semi-quantitative estimates of the λmax of these challenging dyes. It turned out that a PCM-TD-BMK/6-311+G(2d,p)//PCM-PBE0/6-311G(2d,p) approach delivers appropriate lower bounds of the experimental results, despite the inherent limits of the vertical approximation. On the other hand, the method is applied to design new dyes absorbing in the near-IR. The spectral features of ca. 30 new compounds have been simulated in a systematic way, trying to efficiently combine several available synthetic strategies leading to significant bathochromic displacements. A series of dyes absorbing above 850 nm are proposed, illustrating that (relatively) fast theoretical calculations might be a useful pre-screening step preceding synthesis.
Co-reporter:José P. Cerón-Carrasco and Denis Jacquemin
RSC Advances 2012 vol. 2(Issue 31) pp:11867-11875
Publication Date(Web):05 Oct 2012
DOI:10.1039/C2RA22389A
We combine ONIOM simulations with an elaborated hydrated DNA model to evaluate the effects of the hydroxyl radical, one of the major products in irradiated cells, on the stability of the guanine–cytosine (G:C) base pair. Our results demonstrate that the addition of the hydroxyl radical to the cytosine moiety results in inter-base hydrogen bonds rearrangements, eventually leading to a so-called rare tautomeric isomer. In these processes, the O6(G)–N4(C) hydrogen bond strength plays a crucial role as one of the driving forces for the double proton transfer. We also demonstrate that the surrounding environment affects the stability of the non-canonical mutagenic forms. As in undamaged DNA, the water molecules of the first hydration shell might catalyze the exchange of protons while π-stacking tunes the energetic profile of the reaction. The degenerative effects of the induced rare tautomers are shown to be governed by the transition states along the PT reactions, which in turn determines their lifetimes.
Co-reporter:Jérôme Graton, Jean-Yves Le Questel, Béatrice Legouin, Philippe Uriac, Pierre van de Weghe, Denis Jacquemin
Chemical Physics Letters 2012 Volume 522() pp:11-16
Publication Date(Web):19 January 2012
DOI:10.1016/j.cplett.2011.11.076
Abstract
We use dispersion-corrected density functional theory approaches (DFT-D) to investigate the structure and properties of complexes constituted of an aromatic tweezer and aromatic molecules. It turns out that a B97-D/6-31G(d) geometry optimisation yields reasonably accurate structural parameters, whereas larger basis sets and the latest DFT-D models are required to adequately mimic the complexation energies measured through NMR experiments. This contribution highlights that ab initio schemes may be pertinent to investigate the binding energies of large association complexes, even when the studied interaction is relatively weak and shows a non specific character, with a significant dispersion contribution.
Co-reporter:Denis Jacquemin, Eric Brémond, Ilaria Ciofini, and Carlo Adamo
The Journal of Physical Chemistry Letters 2012 Volume 3(Issue 4) pp:468-471
Publication Date(Web):January 24, 2012
DOI:10.1021/jz201552x
The accurate simulation of the dye colors remains a significant challenge for theoreticians, notably due to the sensitivity of the human eyes that are able to distinguish variations of hues corresponding to trifling energetic shifts. Using time-dependent density functional theory and two hybrid functionals, we have simulated vibrationally resolved absorption spectra of two anthraquinone derivatives (solvent blue 35 and solvent green 3) solvated in cyclohexane. Comparisons with recent experiments demonstrate the efficiency of the ωB97X-D/6-31++G(d,p) approach for these structures. The impact of microscopic vibronic couplings on the macroscopic chromatic coordinates of the dyes is quantified. This work unravels the key role of these couplings and is consequently a step further in the modeling of human-perceived colors from purely ab initio models.Keywords: anthraquinone; colors; dyes; TD-DFT; vibronic effects;
Co-reporter:Ilaria Ciofini, Tangui Le Bahers, Carlo Adamo, Fabrice Odobel, and Denis Jacquemin
The Journal of Physical Chemistry C 2012 Volume 116(Issue 22) pp:11946-11955
Publication Date(Web):May 9, 2012
DOI:10.1021/jp3030667
Time-dependent density functional theory calculations are performed within a range-separated hybrid framework to quantify the efficiency of through-space charge transfer (CT) in organic rod-like push–pull compounds. Our model allows us to quantify the CT distance, the amount of transferred electron, as well as the spread of the charges. The impact of several kinds of variations has been investigated: (1) the nature and length of the π-conjugated bridge; (2) the strength of the terminal groups; (3) the presence of a central groups; and (4) the use of a polar environment. In α,ω-nitro-dimethylamino chains, we found that the charge transfer is maximized when four to six conjugated rings are separating the donor and the acceptor. The maximum CT distance is ca. 5 Å for these chains but can be improved by 1–2 Å in polar environments. Adding a stronger electron-donating group does not systematically induce an enhancement of the CT if a strong electron-accepting moiety is used, the latter tending to extract the electron from the conjugated chains rather from the donor moiety. There is indeed a fine equilibrium to respect to improve CT. This investigation is a further step toward the rational optimization of charge transfer properties.
Co-reporter:Jérôme Graton, Béatrice Legouin, François Besseau, Philippe Uriac, Jean-Yves Le Questel, Pierre van de Weghe, and Denis Jacquemin
The Journal of Physical Chemistry C 2012 Volume 116(Issue 43) pp:23067-23074
Publication Date(Web):October 9, 2012
DOI:10.1021/jp307188q
The interactions of small organic molecules with a recently designed molecular tweezer have been modeled using density functional theory approaches. The weak values of the complexation constants of the different compounds make the computations particularly challenging. Nevertheless, the selected theoretical approach is shown to be able to detect several outliers that have been then reexamined by experimental means. The autoassociation, as cyclic dimers, of two carboxylic acids is shown to significantly disturb the 1:1 ligand@host equilibrium constants. Indeed, in CH2Cl2 solutions, the complexes mainly present a 2:1 ligand@host structure. This investigation is a further step toward the rational design of molecular tweezers.
Co-reporter:Emilie Cauët, Denis Jacquemin
Chemical Physics Letters 2012 s 519–520() pp: 49-53
Publication Date(Web):
DOI:10.1016/j.cplett.2011.11.021
Co-reporter:Céline Dupont, Élise Dumont, and Denis Jacquemin
The Journal of Physical Chemistry A 2012 Volume 116(Issue 12) pp:3237-3246
Publication Date(Web):February 29, 2012
DOI:10.1021/jp211875r
We assess the efficiency of density functionals for the description of UV–vis signatures of temporary anions featuring a three-electron two-center bond, along a representative set of systems ranging from (pseudo)dihalides to disulfide radical anions (dimethyl disulfide and lipoate). While BH&HLYP and B3LYP have been predominantly applied to perform such simulations so far, we outline the significantly improved performance of several recently proposed functionals, including range-separated hybrids for the computation of these specific vertical transitions.
Co-reporter:Denis Jacquemin, Eric Brémond, Aurélien Planchat, Ilaria Ciofini, and Carlo Adamo
Journal of Chemical Theory and Computation 2011 Volume 7(Issue 6) pp:1882-1892
Publication Date(Web):May 10, 2011
DOI:10.1021/ct200259k
Vibrationally resolved absorption spectra of a series of anthraquinoidic dyes have been obtained with a polarizable continuum model time-dependent density functional theory approach. Firstly, we assessed the impact of the atomic basis set on both the transition energies and the vibronic shapes of 1,4-NH2-anthraquinone using a large panel of Pople’s basis sets, up to the 6-311++G(3df,3pd). In a second stage, an extensive functional benchmark has been performed to determine an adequate approach for the same compound. In the third step, a complete analysis of the origin of the band shape was performed for the same derivative. In the fourth stage, a set of functionals has been applied to investigate the position isomers in the dihydroxy anthraquinone series. Finally, in a last phase, the methodology has been used for three dyes of technological interest. It turns out that the chosen basis set has a relatively limited impact on the computed transition energies as well as the topology of the vibronic shape, but both are significantly influenced by the selected functional. In the present case, no single functional simultaneously provides highly accurate positions and intensities of the different bands, but ωB97XD appears to be a good compromise. This analysis allows to rationalize the difference in shapes experimentally noticed for the visible band of apparently similar anthraquinones.
Co-reporter:Denis Jacquemin and Carlo Adamo
Journal of Chemical Theory and Computation 2011 Volume 7(Issue 2) pp:369-376
Publication Date(Web):December 29, 2010
DOI:10.1021/ct1006532
We have computed the bond length alternation (BLA) in a series of π-conjugated quasilinear chains containing from two to six unit cells. Several structures (eight oligomeric sets including three conformers of polyacetylene, polymethineimine, polysilaacetylene, etc.) have been considered to cover the possible evolutions of the BLA with increasing chain length. Three objectives have been tackled: (1) the computation of accurate reference values using the CCSD(T) theory; (2) an evaluation of the performances of other electron correlated wave function approaches (MPn, SCS-MP2, CCSD, etc.); (3) the benchmarking of several DFT functionals, including global, range-separated, and double hybrids. It turns out that the SCS-MP2 approach is, on average, an efficient scheme in terms of its accuracy/cost ratio. Among the selected DFT approaches, no single functional emerges as uniformly accurate for all oligomeric series and chain lengths, but BHHLYP, M06-2X, and CAM-B3LYP could be reasonable choices for long oligomers.
Co-reporter:Denis Jacquemin, Benedetta Mennucci and Carlo Adamo
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 38) pp:16987-16998
Publication Date(Web):31 Aug 2011
DOI:10.1039/C1CP22144B
In this perspective, we present an overview of recent progress on Time-Dependent Density Functional Theory (TD-DFT) with a specific focus on its accuracy and on models able to take into account environmental effects, including complex media. To this end, we first summarise recent benchmarks and define an average TD-DFT accuracy in reproducing excitation energies when a conventional approach is used. Next, coupling of TD-DFT with models able to account for different kinds of interactions between a central chromophore and nearby chemical objects (solvent, organic cage, metal as well as semi-conducting surface) is investigated. Examples of application to excitation properties are presented, allowing to briefly describe several recent computational strategies. In addition, an extension of TD-DFT to describe a phenomenon involving interacting chromophores, e.g. the electronic energy transfer (EET), is presented to illustrate that this methodology can be applied to processes beyond the vertical excitation. This perspective therefore aims to provide to non-specialists a flavour of recent trends in the field of simulations of excited states in “realistic” situations.
Co-reporter:Aurélie Perrier, François Maurel and Denis Jacquemin
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 30) pp:13791-13799
Publication Date(Web):30 Jun 2011
DOI:10.1039/C1CP21007F
Using Time-Dependent Density Functional Theory, we have assessed the structural, energetic and spectroscopic properties of a hybrid diarylethene–dihydroazulene multi-addressable switch synthesized by Mrozek et al. [Chem. Commun., 1999, 1487–1488]. All possible closed/open structures have been considered and the different activation barriers along each reaction path have been evaluated. The determination of the energetic profiles allowed us to pinpoint the thermally possible reactions. To simulate the electronic absorption spectra of this compact two-way four-state hybrid compound, we relied on a PCM–TD-DFT approach combined with a molecular orbital analysis. Key insights are reached and the experimental photochromic properties of this multi-component switch are rationalised. From a more methodological point of view, this work also shows that range-separated hybrid functionals (CAM-B3LYP and ωB97XD) allow to reproduce the measured spectroscopic features with a remarkable accuracy.
Co-reporter:Aurélie Perrier, François Maurel, Denis Jacquemin
Chemical Physics Letters 2011 Volume 509(4–6) pp:129-133
Publication Date(Web):14 June 2011
DOI:10.1016/j.cplett.2011.04.074
Abstract
Using a combination of Time-Dependent Density Functional Theory calculations and molecular orbital analysis, the electronic properties of two diarylethene dimers have been investigated in all their possible forms (doubly closed, closed-open and doubly open). The selected ab initio method allows to systematically reproduce the measured spectral features with a remarkable accuracy, and to gain insights into the observed full or partial photochromism. Indeed, in the first dimer, the two DA are mostly independent, whereas in the second, the photochromism is lost due to the π-conjugation. In this second case, the fluorescence spectrum has been simulated with TD-DFT as well.
Co-reporter:Aurélie Perrier, François Maurel, Ilaria Ciofini, Denis Jacquemin
Chemical Physics Letters 2011 Volume 502(1–3) pp:77-81
Publication Date(Web):18 January 2011
DOI:10.1016/j.cplett.2010.12.044
Abstract
This Letter is a theoretical investigation of the ground and excited-state properties of diarylethenes coupled through a platinum-containing bridge. Our simulations are performed using (Time-Dependent) Density Functional Theory in conjunction with the Polarisable Continuum Model and aim at characterising the coupling between the two photochromes. It turns out that theory provides results in very good agreement with experiment for the IR, NMR and UV/Vis spectroscopies. The states and orbitals involved in the relevant UV transitions are analysed, allowing to obtain insights regarding the successive electro-cyclisations, the second probably using a triplet pathway.
Co-reporter:Denis Jacquemin, Eric A. Perpète, François Maurel, Aurélie Perrier
Computational and Theoretical Chemistry 2011 Volume 963(Issue 1) pp:63-70
Publication Date(Web):January 2011
DOI:10.1016/j.comptc.2010.09.009
Using ab initio spectroscopic tools, we have studied the structural and electronic properties of an hybrid dithienylethene–indolinooxazolidine switch synthesized by Pozzo and coworkers [Photochem. Photobiol. Sci. 9 (2010) 131]. To simulate the electronic absorption spectra of this mixed photochrome, we relied on a PCM-TD-DFT approach. Several functionals have been considered, namely the PBE0 global hybrid as well as four range-separated hybrids (CAM-B3LYP, LC-ωPBE, ωB97X and ωB97XD). On average, considering all four closed/open structures, ωB97XD provides the best compromise for estimating the transition wavelengths. It is shown that the TD-DFT procedure combined with an analysis of the molecular orbitals implied in the absorption bands provide insights into the observed photochromic pathways.
Co-reporter:Yann Pellegrin, Loïc Le Pleux, Errol Blart, Adèle Renaud, Benoit Chavillon, Nadine Szuwarski, Mohammed Boujtita, Laurent Cario, Stéphane Jobic, Denis Jacquemin, Fabrice Odobel
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 219(2–3) pp:235-242
Publication Date(Web):15 April 2011
DOI:10.1016/j.jphotochem.2011.02.025
In this contribution, we investigate the photovoltaic performances of four ruthenium trisbipyridine complexes in NiO based dye-sensitized solar cells (DSSC). The four complexes differ by the nature of the anchoring groups, which are either carboxylic acids, biscarbodithioic acids catechol or methyl phosphonic acids. The properties of the dyes were studied by electrochemistry, absorption and emission spectroscopies, surface binding measurements, time-dependent density functional theory (TDDFT) as well as by determining their photoconversion efficiencies in DSSCs under AM 1.5. We show that these simple dyes are relatively efficient sensitizers in NiO-based DSSCs, since some of them give photoconversion efficiencies comparable to that of a standard benchmark dye coumarin C343. We also demonstrate that both catechol and methyl phosphonic acid are promising binding groups for NiO sensitizers to replace classical carboxylic acids in NiO sensitizers and finally we report molecular design rules to elaborate a new generation of better performing ruthenium polypyridine sensitizers.Graphical abstractRuthenium polypyridine complexes show promising potential as sensitizer in NiO-based dye-sensitized solar cells.Highlights► Four ruthenium trisbipyridine complexes were tested in NiO based edye-sensitized solar cells. ► Four different anchoring groups (carboxylic acids, biscarbodithioic acids, catechol and methyl phosphonic acids) were used to chimisorbe the dye on NiO. ► We show that ruthenium polypyridine complexes show promising potential as sensitizer in NiO-based dye-sensitized solar cells. ► Catechol and methyl phosphonic acid can replace the classical carboxylic acid anchoring group.
Co-reporter:Dr. José P. Cerón-Carrasco; Denis Jacquemin
ChemPhysChem 2011 Volume 12( Issue 14) pp:2615-2623
Publication Date(Web):
DOI:10.1002/cphc.201100264
Abstract
Metallic ions are essential for stabilizing the nucleic acid structure, and are also involved in the majority of RNA and DNA biological functions. However, at large concentrations metals may play an opposite role by promoting alterations in the genetic code (mutagenicity). To contribute to the understanding of this effect, theoretical tools are used to investigate the influence of the magnesium dication on the guanine–cytosine (GC) base pair structure and stability. To this end, a fully hydrated Mg2+ cation is inserted in two models: an isolated GC base pair, and a more realistic DNA model corresponding to a hydrated double-stranded trimer. Calculations performed with a hybrid ONIOM approach reveal that the Mg2+ cation coordination to the GC base pair alters drastically the natural tautomeric equilibria in DNA by promoting single proton transfer. Nevertheless, the generated rare tautomer will have a limited impact on the total spontaneous mutation due to the low back-reaction barrier allowing a quick return to the canonical form. Additionally, it is demonstrated that the major effects of biological environment arise from the hydration and stacking influence, whereas the impact of phosphate groups is minor.
Co-reporter:Julien Warnan, Ludovic Favereau, Yann Pellegrin, Errol Blart, Denis Jacquemin, Fabrice Odobel
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 226(Issue 1) pp:9-15
Publication Date(Web):15 December 2011
DOI:10.1016/j.jphotochem.2011.09.023
Two novel TiO2 sensitizers, based on the highly stable diketopyrrolopyrrole (DPP) skeleton, have been synthesized for application in the field of dye sensitized solar cells. The obtained dyes, DPP1 and DPP2 bear respectively a cyanoacrylic acid and a rhodanine acid anchoring groups, thus tuning the extent of the electronic communication with the semi-conducting oxide. The two chromophores were characterized by solution phase spectroscopy and electrochemistry. DFT calculations gave deeper insight into the electronic structure of both dyes, through the disclosure of their frontier orbitals. Photovoltaic performances unravelled the undisputable advantage of DPP1 over DPP2, owing to the combination of a favourable dipolar moment interaction with TiO2, and more intimate orbital blending between the chemisorbed dye and the conduction band. Chenodeoxycholic acid proved to be useful in limiting the formation of dye aggregates, improving to a great extent the performances of DPP1 based DSSCs, reaching in our conditions a 4.47% yield and 57% IPCE at 500 nm.Graphical abstractHighlights► Two novel compact diketopyrrolopyrrole-like dyes have been synthesized. ► Their efficiency in TiO2-based DSSC devices is assessed. ► DPP1 bearing a cyanoacrylic anchoring group shows a photoconversion efficiency of 4.5% under AM1.5.
Co-reporter:François Maurel, Aurélie Perrier, Denis Jacquemin
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 218(Issue 1) pp:33-40
Publication Date(Web):5 February 2011
DOI:10.1016/j.jphotochem.2010.11.021
We simulate the properties of a photochromic blend synthesized by Myles, Wigglesworth and Branda [Adv. Mater. 15 (2003) 745] using ab initio tools. This hybrid multi-addressable molecular switch contains a dithienylethene moiety linked to a phenoxynaphthacenequinone group and exhibits four isomers with distinguishable excited-state features. In the first part of this work, we investigate the properties of model (isolated) dithienylethene and phenoxynaphthacenequinone photochromes, with a focus on the second family that was not fully characterized theoretically previously. In the second stage, the spectral properties of the blend are evaluated with the help of (Time-Dependent) Density Functional Theory.
Co-reporter:Aurélie Perrier ; François Maurel
The Journal of Physical Chemistry C 2011 Volume 115(Issue 18) pp:9193-9203
Publication Date(Web):April 15, 2011
DOI:10.1021/jp201229q
The structures and electronic features of five complex multiphotochromic molecules incorporating two or three diarylethene units are investigated with quantum mechanical approaches. Four out of the five systems only display partial photochromism, and it is shown that the interplay between steric and electronic effects might explain this outcome. For a spiro-bonded system (I), the doubly closed isomer is reachable because the two photochromes are essentially independent and undergo no specific geometric stress. For a tetrathiafilvalene-bridged derivative (II), there is no steric hindrance, but promoting the electron toward the reactive orbital is not possible. In dimers sharing a central thiophene ring (III and IV), the absence of the closed–closed derivative can be understood by either the compactness of the molecule or by a combination of conformational and electronic (lack of photochromic orbital) factors. Eventually, the reactivity of the trimer, V, is related to the variations of the distances between reactive carbon atoms. This contribution therefore paves the way toward an atomic-scale description of elaborated coupled switches and gives hints for the design of more efficient multiaddressable structures, by proposing a new architecture.
Co-reporter:Marco Cipolloni ; Arnault Heynderickx ; François Maurel ; Aurélie Perrier ; Denis Jacquemin ; Olivier Siri ; Fausto Ortica ;Gianna Favaro
The Journal of Physical Chemistry C 2011 Volume 115(Issue 46) pp:23096-23106
Publication Date(Web):October 11, 2011
DOI:10.1021/jp205681p
A recently synthesized and structurally characterized bisdiarylethene containing a benzobis(imidazole) core substituted with two aniline moieties has been investigated from spectroscopic, thermodynamic, and photochemical points of view, using both experimental and theoretical tools. Due to the presence of four basic centers and of two photochromic diarylethenes in the molecular structure, the solutions of this compound change color upon acid addition and/or UV irradiation. Neutralization and/or visible irradiation lead to bleaching. In a water/dioxane (1/1, v/v) mixture, pKa values and absorption spectra of the open and closed neutral and protonated species, as well as quantum yields of the photochromic cyclization and cycloreversion processes, have been determined at selected pH/H0 values by spectrophotometric and photostationary spectrokinetic methods. Time-dependent density functional theory simulations have been carried out and provide insight into the protonation sites and photochromic properties. The results show that the four acidity constants overlap within a restricted pH/H0 interval (4.5/–1.5) generating spectra of the colorless and colored forms that progressively shift toward the red. The possibility of continuously tuning the color of the solutions by external stimuli, such as irradiation and acidification, generates a multiswitchable acidichromic and photochromic material.
Co-reporter:Denis Jacquemin, Catherine Michaux, Eric A. Perpète, and Gilles Frison
The Journal of Physical Chemistry B 2011 Volume 115(Issue 13) pp:3604-3613
Publication Date(Web):March 16, 2011
DOI:10.1021/jp200139q
The determination of the structures and relative energies of microsolvated complexes remains an important challenge for theoretical chemistry because the number of possible aggregates rapidly increases when more solvent molecules are considered. Several approaches (chemical intuition, hierarchy of scheme, evolutionary trees, ...) have been proposed previously to identify the most stable geometries. In the present paper, we compare both the structures and interaction energies computed with different computational protocols for the model case of microhydrated protonated glycine, a system for which experimental complexation enthalpies are available. We compare the results obtained, one the one hand, by a hierarchical approach starting with a AMOEBA search followed by DFT and MP2 refinements and, on the other hand, by a Darwinian tree that uses evolutionary logic and counterpoise corrected MP2 calculations. It is shown that the two approaches yield relatively similar conclusions, though some structures can only be identified by one of the two strategies. This paper therefore underlines the interest of applying more than one minima search tactic for pinpointing all possible microsolvated complexes.
Co-reporter:Denis Jacquemin
The Journal of Physical Chemistry A 2011 Volume 115(Issue 11) pp:2442-2445
Publication Date(Web):March 1, 2011
DOI:10.1021/jp200940x
The quest of organic dyes presenting improved electronic features has been extremely active during the last decades, as new structures are necessary to build novel materials such as dye-sensitized solar cells, nonlinear optics commutators, or molecular photochromic switches. Cyanine derivatives occupy a key spot in that scene, as they present intense absorption bands and tunable colors, even when a relatively short π-conjugated path is used. This behavior has often been interpreted as a consequence of a negligible bond length alternation. Recently, Thorley et al. have designed and characterized new cationic compounds that possess the cyanine electronic features, though presenting sizable bond length alternation (Angew. Chem. Int. Ed.2008, 47, 7095−7098). In this contribution, I investigate, with quantum mechanical tools, the size dependence of these properties in model symmetric dyes displaying Thorley’s patterns. Extended chains are simulated in order to obtain insights into the chain length convergence, and the results are compared to those obtained at the same level of theory for classical cyanine architectures. This theoretical work is a step toward the rational development of more efficient π-conjugated compounds.
Co-reporter:Denis Jacquemin, Cyril Peltier and Ilaria Ciofini
The Journal of Physical Chemistry A 2010 Volume 114(Issue 35) pp:9579-9582
Publication Date(Web):August 12, 2010
DOI:10.1021/jp105824x
The development of theoretical schemes allowing for efficient reproduction of the features of electronically excited states remains a challenging task. In that framework, time-dependent density functional theory (TD-DFT) has emerged as an efficient approach for reproducing and understanding the UV/visible spectra of large solvated molecules. In this paper, we investigate the ground and excited-state properties of two carbonyl dyes presenting very similar structures but possessing absorption peaks differing by both their transition energies and their band shapes. Using a global (PBE0) and a range-separated hybrid (CAM-B3LYP), we obtain consistent conclusions demonstrating, for this couple of dyes, the necessity to go beyond the vertical TD-DFT approximation even for a qualitative interpretation. These simulations are striking examples of the interest of using more refined theoretical schemes for correctly evaluating the transition energies of specific carbonyl dyes.
Co-reporter:Boris Le Guennic, Giovanni Scalmani, Michael J. Frisch, Adèle D. Laurent and Denis Jacquemin
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 16) pp:NaN10561-10561
Publication Date(Web):2017/03/28
DOI:10.1039/C7CP01190C
Using a computational approach combining Time-Dependent Density Functional Theory (TD-DFT) and second-order Coupled Cluster (CC2) approaches, we investigate the spectral properties of a large panel of BOIMPY dyes. BOIMPY derivatives constitute a new class of fluorophores that appeared only very recently [Angew. Chem. Int. Ed., 2016, 55, 13340–13344] and display intriguing properties. First, we show that theory is able to reproduce experimental 0–0 energies with reasonable accuracy, and more importantly excellent consistency (R = 0.99). Next, by analyzing the nature of the excited-states, we show that the first electronic transition does not imply a significant charge-transfer character and significantly differs from the one of the parent BODIPYs. Third, we unravel the vibrational modes responsible for the specific band shapes of the BOIMPY derivatives. Finally, using theory to design new compounds, we propose substitution patterns leading to redshifted absorption spectra, up to ca. 1000 nm.
Co-reporter:Cloé Azarias, Roberto Russo, Lorenzo Cupellini, Benedetta Mennucci and Denis Jacquemin
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 9) pp:NaN6453-6453
Publication Date(Web):2017/02/02
DOI:10.1039/C7CP00427C
The excitation energy transfer (EET) allowing the concentration of the energy has been investigated in several multi-BODIPY architectures with the help of an approach coupling time dependent density functional theory to an implicit solvation scheme, the polarizable continuum model. We have first considered several strategies to compute the electronic coupling in a dyad varying the size of the donor/acceptor units, the bridge, the geometries and conformations. We have next studied the electronic coupling in three different architectures for which the EET rate constants have been experimentally measured both from luminescence and transient absorption data and from Förster theory. A good agreement with experimental values was obtained. Finally, in an effort to further improve these systems, we have designed several series of BODIPY triads, investigating the effect of acidochromism, core modifications, the position of the linkage and chemical substitutions on the EET coupling and rate constant. We show that several architectures allow us to increase the EET rate by one order of magnitude compared to the original compound.
Co-reporter:Arnaud Fihey, Roberto Russo, Lorenzo Cupellini, Denis Jacquemin and Benedetta Mennucci
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 3) pp:NaN2052-2052
Publication Date(Web):2016/12/19
DOI:10.1039/C6CP07458H
Dithienylethenes (DTEs) can be assembled to form supramolecular multiphotochromic systems that are highly functional molecular architectures of potential interest for building complex optoelectronic devices. Yet even simple DTE dimers relying on an organic linker may suffer from a partial photoactivity, i.e., only one of the two switches does isomerise. Experimentally, this limited photochromism has been attributed to an excited state energy transfer (EET) between the two DTEs of the multimer; this EET taking place instead of the desired photoinduced cyclisation of the DTE. However, no clear evidences of this phenomenon have been provided so far. In this work we propose the first rationalisation of this potential parasite photoinduced event using a computational approach based on Time-Dependent Density Functional Theory (TD-DFT) for the calculation of the electronic coupling in DTE dimers. Besides quantifying EET in several systems, we dissect the role of through-bond and through-space mechanisms on this process and clarify their dependence on both the nature and length of the bridge separating the two photochromes. The theoretical data obtained in this framework are in full agreement with the experimental outcomes and pave the way toward a molecular design of coupled, yet fully functionals, DTE-based multiswitches.
Co-reporter:Yevgen M. Poronik, Leszek M. Mazur, Marek Samoć, Denis Jacquemin and Daniel T. Gryko
Journal of Materials Chemistry A 2017 - vol. 5(Issue 10) pp:NaN2628-2628
Publication Date(Web):2017/02/09
DOI:10.1039/C7TC00276A
The first route towards pyrrolo[3,2-b]pyrroles containing two azulene moieties at positions 2 and 5 was developed. The key step of this approach is the three-step transformation of pyridine scaffolds into azulene via sequential N-arylation followed by ring-opening and a reaction with cyclopentadiene. The resulting quadrupolar acceptor–donor–acceptor compounds possess interesting optical properties such as bathochromically shifted absorption with the magnitude of the red-shift strongly dependent on the linkage position. Two-photon absorption of these functional dyes is markedly different from that of previously described pyrrolo[3,2-b]pyrroles. The experimental optical spectra were rationalized using time-dependent density functional theory calculations of both the linear and nonlinear optical properties.
Co-reporter:Anouar Belhboub, Florent Boucher and Denis Jacquemin
Journal of Materials Chemistry A 2017 - vol. 5(Issue 7) pp:NaN1631-1631
Publication Date(Web):2017/01/11
DOI:10.1039/C6TC05297E
The recent discovery of donor–acceptor Stenhouse adducts (DASAs) as a novel class of visible light activated photochromes has received considerable attention due to their high potential for original applications. Up to now, the experimental and theoretical studies have mainly focused on the intrinsic physico-chemical properties and photoswitching process of these molecules, as well as on the incorporation of DASAs in multi-organized structures. In this context, we propose here the first study, by means of first-principle calculations, of DASA photochromes adsorbed onto titanium dioxide anatase surfaces. By analyzing the density of states, we show that DASAs are electronically more sensitive to the surfaces in the closed compact form than in the extended π-conjugated one, which is unusual for photochromes. This finding is also supported by an analysis of the energy band gap. A charge transfer study is performed to quantify the interactions taking place within the total systems. In addition, the impact of grafting on the optical properties is investigated using time-dependent density functional theory (TD-DFT).
Co-reporter:Hassib Audi, Zhongrui Chen, Azzam Charaf-Eddin, Anthony D’Aléo, Gabriel Canard, Denis Jacquemin and Olivier Siri
Chemical Communications 2014 - vol. 50(Issue 96) pp:NaN15143-15143
Publication Date(Web):2014/10/10
DOI:10.1039/C4CC07353C
Stepwise synthesis of linear nickel complex oligomer tapes with no need for solid-phase support has been achieved. The control of the length in flat arrays allows a fine-tuning of the absorption properties from the UV to the NIR region.
Co-reporter:José Pedro Cerón-Carrasco and Denis Jacquemin
Chemical Communications 2013 - vol. 49(Issue 69) pp:NaN7580-7580
Publication Date(Web):2013/05/14
DOI:10.1039/C3CC42593B
Intense electric fields activate the mutagenic mechanism of a single guanine–cytosine base pair. Would they be able to induce a permanent mutation in real DNA? This question is addressed here by modeling a DNA-embedded fragment with state-of-the-art theoretical tools. We show how DNA can, in principle, be mutated if an appropriate electric field is applied.
Co-reporter:Kedong Yuan, Julien Boixel, Hubert Le Bozec, Abdou Boucekkine, Henri Doucet, Véronique Guerchais and Denis Jacquemin
Chemical Communications 2013 - vol. 49(Issue 72) pp:NaN7898-7898
Publication Date(Web):2013/07/09
DOI:10.1039/C3CC43754J
The palladium-catalysed direct di-heteroarylation of 1,2-dichloroperfluorocyclohexene with a variety of heteroarenes gives rise in to a new family of 1,2-di(heteroaryl)perfluorocyclohexenes. These derivatives do not exhibit photoreactivity and this unexpected outcome is explained by calculations demonstrating the lack of reactive isomers.
Co-reporter:Siwar Chibani, Boris Le Guennic, Azzam Charaf-Eddin, Adèle D. Laurent and Denis Jacquemin
Chemical Science (2010-Present) 2013 - vol. 4(Issue 5) pp:NaN1963-1963
Publication Date(Web):2013/02/14
DOI:10.1039/C3SC22265A
BODIPY dyes constitute one of the most efficient class of fluorescent molecules, yet their absorption and emission signatures are hardly predictable with theoretical tools. Here, we use a robust Time-Dependent Density Functional Theory approach that simultaneously accounts for solvent and vibrational effects, in order to simulate the optical properties of a large panel of BODIPY derivatives. In particular, this contribution is focussed on the accurate determination of both the 0–0 energies and vibronic shapes, that allow meaningful comparisons between experimental measurements and theoretical simulations. It turns out that Truhlar's M06-2X functional is well suited for modelling the variations of the 0–0 energies induced by side groups, modifications of the skeleton, stiffening or extension of the π-path. Indeed, while the absolute mean deviation remains quite sizeable, the determination coefficient between experimental and theoretical energies is exceptionally large (R2 = 0.98), highlighting the robustness of the proposed approach. In addition, for most BODIPYs, theory is able to accurately reproduce vibrationally resolved bands. The developed protocol was successfully applied to provide insights for both pH and ion sensors. It also allowed the understanding of the optical behaviours of a series of BODIPY dimers and NIR dyes. This constitutes an unprecedented investigation of several BODIPY dyes both in terms of the number of treated molecules (more than sixty) and of the reliability of the predictions.
Co-reporter:Kathy J. Chen, Adèle D. Laurent, Florent Boucher, Fabrice Odobel and Denis Jacquemin
Journal of Materials Chemistry A 2016 - vol. 4(Issue 6) pp:NaN2227-2227
Publication Date(Web):2016/01/15
DOI:10.1039/C5TA10421A
Although copper thiocyanate (CuSCN) shows potential as a substrate for p-type dye sensitised solar cells, its interaction with organic anchoring groups remains largely unexplored. In this ab initio study, we provide atomistic insight into how CuSCN surfaces interact with a series of nitrogen-based (pyridine, aniline, phenanthroline, benzenediamine) and sulfur-based (thiophenol, thiophenoxide, thiocatechol) anchoring groups. We profile several low-index surfaces, including both polar and nonpolar cleavages, to determine their stabilities and electronic structures. In screening these surfaces for the most favourable adsorption modes and binding sites for organic anchors, we found that adsorption is chiefly driven by the propensity of surface copper atoms to restore a tetrahedronal coordination environment. We show that the majority of the tested anchors, even the bidentate structures, exhibit low binding energies on CuSCN, which illustrates how chemical intuition may be misleading for identifying the ideal anchors on the basis of nucleophilicity and denticity alone. By pinpointing the causes of modest adsorption energies, we present hints as to how adsorption strength and alignment of the organic–inorganic states can be improved on CuSCN.
Co-reporter:Gabriel Marchand, Patrick Giraudeau, Zhongrui Chen, Mourad Elhabiri, Olivier Siri and Denis Jacquemin
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 14) pp:NaN9615-9615
Publication Date(Web):2016/03/09
DOI:10.1039/C6CP01275B
Understanding the chemical nature and spectroscopic signatures of a new class of organic molecules remains a strong challenge. Azacalixphyrin, the first member of a family of strongly aromatic macrocycles absorbing in the near infrared domain, can exist in several tautomeric forms. Here, we use DFT calculations and NMR measurements to propose the first in-depth investigation of proton exchanges occurring in two forms of azacalixphyrins (non-protonated and protonated). Our results reveal, on the one hand, a very effective solvent-assisted tautomerism in the non-protonated form whereas the intramolecular proton transfer is less probable, and, on the other hand, the presence of a mixture of almost isoenergetic tautomers differing in both their aromaticity and absorption profiles. This clearly indicates that smartly-designed chemical substitutions could alter the relative weights of the different tautomers, and consequently tune the optical signatures of these new macrocycles in a versatile and efficient way. For the protonated form, rotations of the NH2 groups take place rather than the chemical exchange.
Co-reporter:José Pedro Cerón-Carrasco, Javier Cerezo and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 18) pp:
Publication Date(Web):
DOI:10.1039/C3CP54518K
Co-reporter:Denis Jacquemin, Benedetta Mennucci and Carlo Adamo
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 38) pp:NaN16998-16998
Publication Date(Web):2011/08/31
DOI:10.1039/C1CP22144B
In this perspective, we present an overview of recent progress on Time-Dependent Density Functional Theory (TD-DFT) with a specific focus on its accuracy and on models able to take into account environmental effects, including complex media. To this end, we first summarise recent benchmarks and define an average TD-DFT accuracy in reproducing excitation energies when a conventional approach is used. Next, coupling of TD-DFT with models able to account for different kinds of interactions between a central chromophore and nearby chemical objects (solvent, organic cage, metal as well as semi-conducting surface) is investigated. Examples of application to excitation properties are presented, allowing to briefly describe several recent computational strategies. In addition, an extension of TD-DFT to describe a phenomenon involving interacting chromophores, e.g. the electronic energy transfer (EET), is presented to illustrate that this methodology can be applied to processes beyond the vertical excitation. This perspective therefore aims to provide to non-specialists a flavour of recent trends in the field of simulations of excited states in “realistic” situations.
Co-reporter:Aurélie Perrier, François Maurel and Denis Jacquemin
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 30) pp:NaN13799-13799
Publication Date(Web):2011/06/30
DOI:10.1039/C1CP21007F
Using Time-Dependent Density Functional Theory, we have assessed the structural, energetic and spectroscopic properties of a hybrid diarylethene–dihydroazulene multi-addressable switch synthesized by Mrozek et al. [Chem. Commun., 1999, 1487–1488]. All possible closed/open structures have been considered and the different activation barriers along each reaction path have been evaluated. The determination of the energetic profiles allowed us to pinpoint the thermally possible reactions. To simulate the electronic absorption spectra of this compact two-way four-state hybrid compound, we relied on a PCM–TD-DFT approach combined with a molecular orbital analysis. Key insights are reached and the experimental photochromic properties of this multi-component switch are rationalised. From a more methodological point of view, this work also shows that range-separated hybrid functionals (CAM-B3LYP and ωB97XD) allow to reproduce the measured spectroscopic features with a remarkable accuracy.
Co-reporter:Denis Jacquemin, Tangui Le Bahers, Carlo Adamo and Ilaria Ciofini
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 16) pp:NaN5388-5388
Publication Date(Web):2012/02/24
DOI:10.1039/C2CP40261K
We investigate the efficiency of several partial atomic charge models (Mulliken, Hirshfeld, Bader, Natural, Merz–Kollman and ChelpG) for investigating the through-space charge-transfer in push–pull organic compounds with Time-Dependent Density Functional Theory approaches. The results of these models are compared to benchmark values obtained by determining the difference of total densities between the ground and excited states. Both model push–pull oligomers and two classes of “real-life” organic dyes (indoline and diketopyrrolopyrrole) used as sensitisers in solar cell applications have been considered. Though the difference of dipole moments between the ground and excited states is reproduced by most approaches, no atomic charge model is fully satisfactory for reproducing the distance and amount of charge transferred that are provided by the density picture. Overall, the partitioning schemes fitting the electrostatic potential (e.g. Merz–Kollman) stand as the most consistent compromises in the framework of simulating through-space charge-transfer, whereas the other models tend to yield qualitatively inconsistent values.
Co-reporter:Boris Le Guennic, Olivier Maury and Denis Jacquemin
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 1) pp:NaN164-164
Publication Date(Web):2011/11/08
DOI:10.1039/C1CP22396H
The excited-state energies of aza-boron-dipyrromethene (Aza-BODIPY) derivatives are investigated with Time-Dependent Density Functional Theory (TD-DFT), with twin goals. On the one hand, a pragmatic, yet efficient, computational protocol is defined in order to reach rapidly semi-quantitative estimates of the λmax of these challenging dyes. It turned out that a PCM-TD-BMK/6-311+G(2d,p)//PCM-PBE0/6-311G(2d,p) approach delivers appropriate lower bounds of the experimental results, despite the inherent limits of the vertical approximation. On the other hand, the method is applied to design new dyes absorbing in the near-IR. The spectral features of ca. 30 new compounds have been simulated in a systematic way, trying to efficiently combine several available synthetic strategies leading to significant bathochromic displacements. A series of dyes absorbing above 850 nm are proposed, illustrating that (relatively) fast theoretical calculations might be a useful pre-screening step preceding synthesis.
Co-reporter:José P. Cerón-Carrasco, Denis Jacquemin and Emilie Cauët
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 36) pp:NaN12464-12464
Publication Date(Web):2012/03/23
DOI:10.1039/C2CP40515F
We investigate possible mutations in the genetic code induced by cisplatin with an approach combining molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. Specifically, the impact of platination on the natural tautomeric equilibrium in guanine–cytosine (GC) base pairs is assessed to disclose the possible role played by non-canonical forms in anti-tumour activity. To obtain valuable predictions, the main interactions present in a real DNA environment, namely hydration and stacking, are simultaneously taken into account. According to our results, the Pt–DNA adduct promotes a single proton transfer reaction in GC in the DNA sequence AC. Such rare tautomers might play an important role in the cisplatin biological activity since they meet the stability requirements necessary to promote a permanent mutation.
Co-reporter:Boris Le Guennic, Siwar Chibani, Azzam Charaf-Eddin, Julien Massue, Raymond Ziessel, Gilles Ulrich and Denis Jacquemin
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 20) pp:NaN7540-7540
Publication Date(Web):2013/03/21
DOI:10.1039/C3CP50669J
The optical properties of a series of recently synthesized [Chem. Eur. J., 2013, DOI: 10.1002/chem.201203625] fluorescent borate complexes based on the 2-(2′-hydroxyphenyl)benzoxazole (HBO) core have been modeled using Time-Dependent Density Functional Theory. The computations use a range-separated hybrid functional (ωB97X-D) and include vertical, adiabatic and vibronic simulations, as well as analysis of the charge-transfer characteristics of each state. This work allows us to interpret the major experimental features, including unexpected evolution of the λmax, band shapes and protonation effects. Two dyads, one including a BODIPY core, have also been tackled.
Co-reporter:Siwar Chibani, Šimon Budzák, Miroslav Medved', Benedetta Mennucci and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 47) pp:NaN26029-26029
Publication Date(Web):2014/10/13
DOI:10.1039/C4CP03919J
We compare the solvatochromic shifts measured experimentally and obtained theoretically for the emission of several substitued fluorophores (indole, benzofurazan, naphthalimide…). Our theoretical protocol relies on time-dependent density functional theory and uses several variations of the polarisable continuum model. In particular, we compare the merits of the linear-response and the corrected linear response approaches, the latter being used for both energetic and structural calculations. It turns out that performing fully-consistent corrected linear response calculations yields the smallest mean signed and absolute errors for the solvatochromic shifts, although optimizing the excited-state structures at the linear-response level only induces limited increase of the average deviations. In contrast, for auxochromic effects, the average errors provided by the two solvation models are very similar.
Co-reporter:Stéphane Aloïse, Ruan Yibin, Ismail Hamdi, Guy Buntinx, Aurélie Perrier, François Maurel, Denis Jacquemin and Michinori Takeshita
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 48) pp:NaN26768-26768
Publication Date(Web):2014/10/22
DOI:10.1039/C4CP03641G
The photophysical properties of a series of dithienylethenes, free or blocked in an ideal photoactive conformation by an alkyl bridge, have been investigated by stationary, ultrafast spectroscopy and state-of-the-art time-dependent density functional theory calculations. Thanks to the clear ultrafast transient signatures corroborating NMR results, we bring strong evidence that the unreactive parallel open form conformer has been efficiently removed by the chain. For the first time, the photophysics of this species, namely an internal conversion of 120 ps is highlighted. In contradiction to the main ideas in the literature, the photocyclization mechanism is rationalized by a direct photocyclization mechanism from the Franck–Condon region passing directly through a conical intersection within ≈100 fs (not few picoseconds) while a competitive mechanism occurs through the relaxed S1 state. Relaxation processes (fluorescence and internal conversion) originating from this relaxed state are sensitive to the length of the blocking chain. Both concomitant pathways are necessary to rationalize: (i) the inverse relationship between emission and cyclization quantum yields and (ii) the non-unity value of the latter for bridged compounds.
Co-reporter:Pierre O. Hubin, Adèle D. Laurent, Daniel P. Vercauteren and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 46) pp:NaN25295-25295
Publication Date(Web):2014/09/30
DOI:10.1039/C4CP03223C
Thermodynamic and kinetic aspects of excited state intramolecular proton transfer (ESIPT) are investigated in 11 chromophores harboring an intramolecular N–H⋯N hydrogen bond [pyridyl pyrazole, pyridyl pyrrole, azaindole, pyridyl indole, pyrroloquinoline, and an analogue of the Blue Fluorescent Protein (BFP) chromophore] with the help of quantum mechanical calculations. For pyridyl pyrazoles, simulated spectra are used to help the interpretation of experimental ones and the effects of several substituents are investigated. Then it is shown that Time-Dependent Density Functional Theory fails to satisfactorily describe the energetic aspects of ESIPT for the BFP chromophore analogue. Equation-of-Motion Coupled Cluster theory is thus used to reach accurate insights for this challenging case.
Co-reporter:Adèle D. Laurent, Carlo Adamo and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 28) pp:NaN14356-14356
Publication Date(Web):2014/01/30
DOI:10.1039/C3CP55336A
In this perspective, we present an overview of the determination of excited-state properties of “real-life” dyes, and notably of their optical absorption and emission spectra, performed during the last decade with time-dependent density functional theory (TD-DFT). We discuss the results obtained with both vertical and adiabatic (vibronic) approximations, choosing relevant examples for several series of dyes. These examples include reproducing absorption wavelengths of numerous families of coloured molecules, understanding the specific band shape of amino-anthraquinones, optimising the properties of dyes used in solar cells, mimicking the fluorescence wavelengths of fluorescent brighteners and BODIPY dyes, studying optically active biomolecules and photo-induced proton transfer, as well as improving the properties of photochromes.
Co-reporter:David Mendive-Tapia, Aurélie Perrier, Michael J. Bearpark, Michael A. Robb, Benjamin Lasorne and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 34) pp:NaN18471-18471
Publication Date(Web):2014/07/18
DOI:10.1039/C4CP03001J
The photochromic properties of diarylethenes, some of the most studied class of molecular switches, are known to be controlled by non-adiabatic decay at a conical intersection seam. Nevertheless, as their fatigue-reaction mechanism – leading to non-photochromic products – is yet to be understood, we investigate the photo-chemical formation of the so-called by-product isomer using three complementary computational methods (MMVB, CASSCF and CASPT2) on three model systems of increasing complexity. We show that for the ring-opening reaction a transition state on S1(2A) involving bond breaking of the penta-ring leads to a low energy S1(2A)/S0(1A) conical intersection seam, which lies above one of the transition states leading to the by-product isomer on the ground state. Therefore, radiationless decay and subsequent side-product formation can take place explaining the photo-degradation responsible for the by-product generation in diarylethene-type molecules. The effect of dynamic electron correlation and the possible role of inter-system crossing along the penta-ring opening coordinate are discussed as well.
Co-reporter:Claudine Katan, Paul Savel, Bryan M. Wong, Thierry Roisnel, Vincent Dorcet, Jean-Luc Fillaut and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 19) pp:NaN9073-9073
Publication Date(Web):2014/03/25
DOI:10.1039/C4CP00478G
In the continuous quest for improving TD-DFT methodologies as a tool to predict the photophysical features of solvated chromophores, we investigate two model regioisomers based on the 1,2,3-triazole moiety. Starting from their experimental absorption and emission spectra, key energy differences highlighting the main trends between the two isomers are extracted and used to gauge the accuracy of several levels of theory. RI-CC2 and EOM-CCSD calculations allow us to ascertain that the low energy spectra are not linked to double excitations. In a vacuum, none of these methods nor any of the implemented TD-DFT levels of theory, ranging from global hybrids (PBE0, B3LYP) to range-separated functionals without (CAM-B3LYP, ωB97X) or with dispersion corrections (ωB97X-D), are able to capture the key features that differentiate the two chromophores. Accounting for solvent within a specific PCM model allows us to recover experimental trends, but the dramatic changes occurring when moving from toluene to THF and/or when using different PCM approaches (LR, cLR, SS) suggest that this agreement is probably fortuitous. Even if the ωB97X-D functional combined with the SS-PCM scheme leads to quantitative agreement with experiment, TD-DFT results obtained for 1,2,3-triazole based chromophores need to be treated with caution. We also show that the SS-PCM approach may be useful to test current and novel exchange–correlation functionals against the charge transfer failure.
Co-reporter:Ymène Houari, Azzam Charaf-Eddin, Adèle D. Laurent, Julien Massue, Raymond Ziessel, Gilles Ulrich and Denis Jacquemin
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 4) pp:NaN1321-1321
Publication Date(Web):2013/11/14
DOI:10.1039/C3CP54703E
The potential energy surfaces of dyes displaying strong excited-state intramolecular proton transfer (ESIPT) are investigated with the help of ab initio tools. It allows us to rationalize the interplay between the excited-state transition free energies and the observed optical signatures.
Co-reporter:Gabriel Marchand, Hélène Roy, David Mendive-Tapia and Denis Jacquemin
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 7) pp:NaN5297-5297
Publication Date(Web):2015/01/08
DOI:10.1039/C4CP05158K
Using first-principle calculations, we characterize the properties of N-confused porphyrins (NCP), with a focus on the differences between the 2H and 3H tautomers. We find that NCP-3H is almost as strongly aromatic as porphyrin, and about twice as aromatic, i.e., remarkably more stable, than NCP-2H, due to the less efficient π-conjugation in the latter form. The deprotonation of the NH-group at the external side of the inverted ring of NCP-2H, adds a lone pair to the π-system, which restores a strong aromaticity, while methylation has no significant effect. Investigating the impact of solvation using a continuum model, we find quite stable solvation energies with a relative dielectric constant, εr, in the 5–40 range, for both tautomers. NCP-3H presents a slightly lower energy than its NCP-2H counterpart in all solvents. However, the energy differences between the two species are of the order of the error margin of the method, hence too small to discuss the experimentally observed stabilization of NCP-3H in dichloromethane (DCM, a poorly polar solvent) and NCP-2H in N,N-dimethylformamide (DMF, a strongly polar solvent) or to extract the population ratios between the two forms in the different solvents. Therefore, the vibronic absorption spectra are also investigated in an effort to rationalize the complex absorption profiles of these NCP derivatives. We find very distinct spectra for the 2H and 3H forms in DMF and DCM, respectively, each fairly reproducing the experiment. We also find that, in the same solvent, the two species exhibit very different signatures, which allows us to conclude that the 2H and 3H tautomers are largely dominant in DMF and DCM, respectively. Interestingly, the vibrational motions that strongly participate in the shoulder of the Soret band and the multiple maxima of the Q-bands largely differ in the two tautomers.
Co-reporter:Arnaud Fihey, Anthony Favennec, Boris Le Guennic and Denis Jacquemin
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 14) pp:NaN9366-9366
Publication Date(Web):2015/10/23
DOI:10.1039/C5CP05653E
We investigate with a hybrid SOS-CIS(D)/TD-DFT approach accounting for solvation effects, the structural, electronic and optical properties of recently-proposed PODIPY dyes. Being more soluble in water than the well-known BODIPYs, these new chromogens are particularly appealing, but their characterization remains very limited. It turns out that the selected theoretical protocol could reproduce the experimentally reported differences between PODIPY and BODIPY dyes. Based on this, we have investigated a large number of new PODIPY dyes and determined their theoretical 0–0 energies.
Co-reporter:Arnaud Fihey, Aurélie Perrier, Wesley R. Browne and Denis Jacquemin
Chemical Society Reviews 2015 - vol. 44(Issue 11) pp:NaN3759-3759
Publication Date(Web):2015/04/29
DOI:10.1039/C5CS00137D
Molecular systems encompassing more than one photochromic entity can be used to build highly functional materials, thanks to their potential multi-addressability and/or multi-response properties. Over the last decade, the synthesis and spectroscopic and kinetic characterisation as well as the modeling of a wide range of multiphotochromes have been achieved in a field that is emerging as a distinct branch of photochemistry. In this review, we provide an overview of the available multiphotochromic compounds which use a variety of photoactive building blocks, e.g., diarylethene, azobenzene, spiropyran, naphthopyran or fulgimide derivatives. Their efficiency in terms of multi-responsiveness is discussed and several strategies to circumvent the most common limitation (i.e., the loss of photochromism of one part) are described.
Co-reporter:Carlo Adamo and Denis Jacquemin
Chemical Society Reviews 2013 - vol. 42(Issue 3) pp:NaN856-856
Publication Date(Web):2012/11/02
DOI:10.1039/C2CS35394F
In this tutorial review, we show how Time-Dependent Density Functional Theory (TD-DFT) has become a popular tool for computing the signatures of electronically excited states, and more specifically, the properties directly related to the optical (absorption and emission) spectra of molecules. We discuss the properties that can be obtained with widely available programs as well as how to account for the environmental effects (solvent and surfaces) and present recent applications in these fields. We next expose the transformation of the TD-DFT results into chemically intuitive parameters (colours as well as charge-transfer distances). Eventually, the non-specialised reader will find a series of advices and warnings necessary to perform her/his first TD-DFT calculations.
Co-reporter:Arnaud Fihey and Denis Jacquemin
Chemical Science (2010-Present) 2015 - vol. 6(Issue 6) pp:NaN3504-3504
Publication Date(Web):2015/04/02
DOI:10.1039/C5SC00856E
Aiming at designing more efficient multiphotochromes, we investigate with the help of ab initio tools the impact of the substitution on a series of dimers constituted of two dithienylethene (DTE) moieties, strongly coupled to each other through an ethynyl linker. The electronic structure and the optical properties of a large panel of compounds, substituted on different positions by various types of electroactive groups, have been compared with the aim of designing a dyad in which the three possible isomers (open–open, closed–open, closed–closed) can be reached. We show that appending the reactive carbons atoms of the DTE core with electroactive groups on one of the two photochromes allows cyclisation to be induced on a specific moiety, which leads to the formation of the desired closed–open isomer. Substituting the lateral positions of the thiophene rings provides further control of the topology of the frontier molecular orbitals, so that the electronic transition inducing the second ring closure stands out in the spectrum of the intermediate isomer.
Co-reporter:Benjamin Lasorne, Arnaud Fihey, David Mendive-Tapia and Denis Jacquemin
Chemical Science (2010-Present) 2015 - vol. 6(Issue 10) pp:NaN5702-5702
Publication Date(Web):2015/06/29
DOI:10.1039/C5SC01960E
Going from photochromic compounds presenting a single switchable function to multi-addressable photochromic multimers remains an extremely difficult task notably because the interactions of several photochromic units through a linker generally result in a substantial loss of photoactivity. Due to their size and the intrinsic complexity of their electronic structure, coupled photochromes also constitute a fundamental challenge for theoretical chemistry. We present here an effective curve-crossing model that, used in connection with easily accessible ab initio data, allows a first understanding of the difficulty to obtain efficient multiphotochromes. Indeed, we demonstrate that extra crossing points, specific to multiphotochromes, have to be passed to ensure reactivity. In addition, the proposed approach allows the definition of an intuitive tilt criterion that can be used to screen a large number of substitution patterns and hence help in the design of new compounds, an aspect that is also developed here. The compatibility of this tilt criterion with previously proposed static Franck–Condon parameters is discussed as well.
Co-reporter:Cloé Azarias, Šimon Budzák, Adèle D. Laurent, Gilles Ulrich and Denis Jacquemin
Chemical Science (2010-Present) 2016 - vol. 7(Issue 6) pp:NaN3774-3774
Publication Date(Web):2016/02/23
DOI:10.1039/C5SC04826E
Dyes undergoing excited-state intramolecular proton transfer (ESIPT) are known to present large Stokes shifts as a result of the important geometrical reorganisation following photon absorption. When the ESIPT process is not quantitative, one can obtain dual emitters characterised by two distinct fluorescence bands, observed due to emissions from both the canonical and ESIPT isomers. However, dual emission generally requires to maintain a very specific balance, as the relative excited-state free energies of the two tautomers have to be within a narrow window to observe the phenomenon. Consequently, simple chemical intuition is insufficient to optimise dual emission. In the present contribution, we investigate, with the help of quantum-mechanical tools and more precisely, time-dependent density functional theory (TD-DFT) and algebraic diagrammatic construction (ADC), a wide panel of possible ESIPT/dual emitters with various substituents. The selected protocol is first shown to be very robust on a series of structures with known experimental behaviour, and next is applied to novel derivatives with various substituents located at different positions. This work encompasses the largest chemical library of potential ESIPT compounds studied to date. We pinpoint the most promising combinations for building dual emitters, highlight unexpected combination effects and rationalise the impact of the different auxochromes.
Co-reporter:Hiroyuki Nitadori, Lucie Ordronneau, Julien Boixel, Denis Jacquemin, Abdou Boucekkine, Anu Singh, Munetaka Akita, Isabelle Ledoux, Véronique Guerchais and Hubert Le Bozec
Chemical Communications 2012 - vol. 48(Issue 84) pp:NaN10397-10397
Publication Date(Web):2012/08/31
DOI:10.1039/C2CC34999J
The modulation of the quadratic NLO response of an octupolar metal-based chromophore featuring four photochromic dithienylethene units is reported. Quantum mechanical simulations are consistent with a full switching of the DTE units and reproduce the strong enhancement of the NLO response.
Co-reporter:Aurélie Perrier, François Maurel, Wesley R. Browne and Denis Jacquemin
Chemical Communications 2013 - vol. 49(Issue 39) pp:NaN4249-4249
Publication Date(Web):2012/10/23
DOI:10.1039/C2CC37043C
First principle simulations of an extended hexameric molecular switch are reported. The full switching of the system is explained by investigating the nature of the excited states of all possible isomers. A new multi-addressable asymmetric structure is proposed.
Co-reporter:Julien Boixel, Véronique Guerchais, Hubert Le Bozec, Agisilaos Chantzis, Denis Jacquemin, Alessia Colombo, Claudia Dragonetti, Daniele Marinotto and Dominique Roberto
Chemical Communications 2015 - vol. 51(Issue 37) pp:NaN7808-7808
Publication Date(Web):2015/04/02
DOI:10.1039/C5CC01893E
An unprecedented DTE-based Pt(II) complex, 2(o), which stands as the first example of a sequential double nonlinear optical switch, induced first by protonation and next upon irradiation with UV light is presented.
Co-reporter:Julien Boixel, Yifan Zhu, Hubert Le Bozec, Mohamed Ali Benmensour, Abdou Boucekkine, Keith Man-Chung Wong, Alessia Colombo, Dominique Roberto, Véronique Guerchais and Denis Jacquemin
Chemical Communications 2016 - vol. 52(Issue 63) pp:NaN9836-9836
Publication Date(Web):2016/07/13
DOI:10.1039/C6CC03431D
We disclose two unprecedented complexes built with a central dithienylethene photochrome connecting two cyclometalated Pt(II) moieties either on the reactive carbon atoms or on the lateral non-reactive carbon atoms of the photochrome. The two systems show vastly different properties that are rationalised thanks to quantum-chemical calculations.
Co-reporter:Mohamed Raoui, Julien Massue, Cloé Azarias, Denis Jacquemin and Gilles Ulrich
Chemical Communications 2016 - vol. 52(Issue 59) pp:NaN9219-9219
Publication Date(Web):2016/06/03
DOI:10.1039/C6CC03745C
The investigation of the optical properties of extended 2-(2-hydroxyphenyl)benzazole dyes showed a complete frustration of the excited-state intramolecular proton transfer (ESIPT) process leading to a novel family of highly fluorescent fluorophores. In the case of a benzothiazole ring, restoration of ESIPT can be observed in acidic medium leading to ratiometric sensing. These experimental results have been rationalised by first-principle calculations.
Co-reporter:David Mendive-Tapia, Luuk Kortekaas, Jorn D. Steen, Aurélie Perrier, Benjamin Lasorne, Wesley R. Browne and Denis Jacquemin
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 45) pp:NaN31253-31253
Publication Date(Web):2016/10/27
DOI:10.1039/C6CP06907J
Photochromism of the spiropyran radical cation to the corresponding merocyanine form is investigated by a combination of electrochemical oxidation, UV/vis absorption spectroscopy, spectroelectrochemistry and first-principles calculations (TD-DFT, CAS-SCF and CAS-PT2). First, we demonstrate that the ring-opening of mono-spiropyrans occurs upon one-electron oxidation and that it can be driven photochemically as well as thermally, with trapping of the merocyanine by protonation. Second, in order to explain this experimentally observed spectroelectrochemical behaviour we suggest a theoretical mechanism based on the reactivity of the two lowest electronic excited-states, which promotes effective electron transfer from the indoline (nitrogen-ring) to the pyran (oxygen-ring) moieties (and vice versa) through a conical intersection seam of degeneracy. Characterisation of the minimum energy conical intersection on this crossing revealed that it presents a rare diabatic trapping topology. The excited state molecule cannot escape from crossing the intersection seam due to the presence of only one degeneracy-lifting coordinate that efficiently channels into the formation of the merocyanine photoproduct, so giving rise to a “kitchen sink” funnel-like effect. Therefore, assuming rapid relaxation after vertical excitation to a higher electronic state, photoconversion cannot be avoided in the D1 electronic state, which rationalises the remarkably efficient visible light driven excited-state reactivity observed experimentally.
Co-reporter:Gabriel Marchand, Olivier Siri and Denis Jacquemin
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 24) pp:NaN15913-15913
Publication Date(Web):2017/05/22
DOI:10.1039/C7CP02600E
Azacalixphyrins (ACP) constitute a new class of macrocycles isoelectronic and isostructural to porphyrins. Herein, we report the first theoretical investigation of the properties of the ACP macrocycles metallated at their centre by titanium, platinum, and iron ions. We considered both the original phenyl-type ACP and new pyridyl-type forms. Our results indicate that the metallation greatly impacts the global structure of the macrocycle through pseudo Jahn–Teller effects, giving rise to a possible conformational transition between D2d and S4 structures. Such an effect could not be found in the metal-free ACPs. In addition, we find that, in contrast to the purely singlet platinum ACPs, and the purely triplet iron ACPs, several spin states are energetically close in the titanium ACPs, especially when weak field ligands are bound in axial positions to the metallic centre. According to TD-DFT calculations, metallation also tunes the optical properties. In particular, the absorption band in the near infrared region undergoes a hypsochromic shift of ca. 100–200 nm when going from the D2d to the S4 structures. We quantify how the addition of electroactive ligands in the axial position can increase or tune down these spectral changes. This contribution therefore supports the development of ACP coordination complexes.
