Sensitive and selective detection of Pb2+ is a very worthwhile endeavor in terms of both human health and environmental protection, as the heavy metal is fairly ubiquitous and highly toxic. In this study, we designed phthalocyanine–porphyrin (Pc-Por) heterodyads, namely, H2Pc-α-ZnPor (1) and H2Pc-β-ZnPor (2), by connecting a zinc(II) porphyrin moiety to the nonperipheral (α) or peripheral (β) position of a metal-free phthalocyanine moiety. Upon excitation at the porphyrin Soret region (420 nm), both of the dyads exhibited not only a porphyrin emission (605 nm) but also a phthalocyanine emission (ca. 700 nm), indicating the occurrence of intramolecular fluorescence resonance energy transfer (FRET) processes from the porphyrin donor to the phthalocyanine acceptor. The dyads can selectively bind Pb2+ in the phthalocyanine core leading to a red shift of the phthalocyanine absorption and thus a decrease of spectral overlap between the porphyrin emission and phthalocyanine absorption, which in turn suppresses the intramolecular FRET. In addition, the binding of Pb2+ can highly quench the emission of phthalocyanine by heavy-metal ion effects. The synergistic coupled functions endow the dyads with remarkable ratiometric fluorescent responses at two distinct wavelengths (F605/F703 for 1 and F605/F700 for 2). The emission intensity ratio increased as a linear function to the concentration of Pb2+ in the range of 0–4.0 μM, whereas the detection limits were determined to be 3.4 × 10–9 and 2.2 × 10–8 M for 1 and 2, respectively. Furthermore, by comparative study of 1 and 2, the effects of distance and relative orientation between Pc and ZnPor fluorophores on the FRET efficiency and sensing performance were highlighted, which is helpful for further optimizing such FRET systems.

•Three pairs of BINOL bridged chiral bisporphyrins were designed and synthesized.•The intramolecular chirality induction effects were revealed by the bisignate CD couplets.•The intermolecular chirality modulation was detected by UV–Vis, 1H NMR and CD titrations with BiPy as the guest.We have studied the intra- and inter-molecular chirogenesis events on a family of chiral bisporphyrin hosts H1-H3. The three pairs of enantiomers for H1-H3 were constructed by connecting two zinc(II) porphyrinates to a homochiral (R)-(+)- or (S)-(−)-1,1′-bi-2-naphthol (BINOL) with ester or ether linkages. Split Cotton effects were observed for all of the bisporphyrin hosts. For each enantiomer, the sign of the bisignate CD couplets directly correlates to the stereostructure of the BINOL linker, namely a (R)-BINOL linker leads to a negative CD couplet and vise versa. The CD intensities of the hosts are decreasing from H1 to H3 along with the increasing of the length and flexibility of the chemical linkages between BINOL and porphyrin subunits. The predictable CD signs and regularly changed CD intensities demonstrate the defined intramolecular asymmetric information transfer, by which the chirality of a BINOL linker is translated to a preferred chiral twist in the inter-porphyrin arrangement with tunable efficiency. Furthermore, the intermolecular binding of 4,4′-BiPyridyl (BiPy), as a typical achiral ditopic guest, to the series of hosts were detected by UV–Vis, 1H NMR and CD spectroscopic titrations. The results indicate a convergent and complementary 1:1 binding mode, in which a BiPy ligand binds to a host molecule by ditopic ZnN coordination forming a stable cyclic supramolecular complex. In particular, the intensity of CD signals decreases significantly for all of the supramolecular complexes in comparison with the chiral bisporphyrin hosts alone, though the CD sign does not change. The observation is rationalized by DFT molecular modeling, which suggests that upon the formation of 1:1 cyclic supramolecular complexes the chiral twist direction of the two porphyrin moieties does not change, while the ZnZn distance increases remarkably. The present results highlight the effects of intramolecular chirality induction and intermolecular chirality modulation in BINOL bridged porphyrin tweezer systems.We have synthesized three pairs of enantiomers for chiral bisporphyrins H1-H3 by connecting two zinc(II) porphyrin units to a homochiral (R)-(+)- or (S)-(−)-1,1′-bi-2-naphthol moiety with ester or ether linkages. The intramolecular chirality induction and intermolecular chirality modulation events have been studied by UV–Vis, 1H NMR and CD spectroscopic techniques with the assistance of DFT molecular modeling.

•BINOL-strapped chiral bis(porphyrinato) cerium complexes were synthesized.•The chirality transfer from a BINOL strap to the double-decker core is observed.•The chirality transfer efficiency can be finely tuned.(R)-(+)- or (S)-(−)-1,1′-bi-2-naphthol (BINOL) was applied as a remote chiral auxiliary to connect the two facing porphyrin rings, resulting in the BINOL-strapped chiral bis(porphyrinato) cerium double-decker complexes (R)-/(S)-1 and (R)-/(S)-2, which were carefully characterized by a range of spectroscopic and electrochemical methods. Perfect mirror images were observed in their circular dichroism (CD) spectra with a negative sign in the Soret band for (R)-enantiomers and a positive sign for (S)-enantiomers, which suggests the C2-chirality of a BINOL strap is transcribed to the double-decker core as a defined chiral twist in the inter-porphyrin arrangement. Furthermore, the CD intensities of (R)-/(S)-1 are always larger than those of (R)-/(S)-2, indicating that the intramolecular chirality transfer efficiency can be finely tuned by changing the length of interlocking moieties.Two pairs of BINOL-strapped chiral bis(porphyrinato) cerium double-decker complexes were synthesized and characterized by a range of spectroscopic and electrochemical methods. The CD spectra suggest that the chirality of a BINOL strap can be translated to a defined chiral twist between the two facing porphyrin rings with tunable efficiency.Download high-res image (207KB)Download full-size image

•A new terbium triple-decker complex was synthesized and characterized.•The molecular structure of compound 1 was determined by X-ray diffraction analysis.•The SMM properties of the new sandwich complex 1 have been studied.Mixed (phthalocyaninato)(tetranaphthylporphyrinato) terbium(III) triple-decker complex [(TNP)Tb(Pc)Tb(TNP)] (1) was synthesized by treating the half-sandwich complex [Tb(TNP)(acac)] (acac = acetylacetonate) with Li2(Pc). Compound 1 represents the first sandwich-type complex containing tetranaphthylporphyrin ligand. This new triple-decker complex was characterized by MALDI-TOF mass, 1H NMR, electronic absorption and IR spectroscopies. The molecular structure was determined by single crystal X-ray diffraction analysis confirming the symmetrical triple-decker structure with two outer TNP ligands and one inner Pc ligand. The static and dynamic measurements for the magnetic properties of complex 1 were conducted. The results indicate the slow relaxation and strong quantum tunneling of magnetization for this symmetrical Tb-Tb magnet.Mixed (phthalocyaninato)(tetranaphthylporphyrinato) terbium triple-decker complex [(TNP)Tb(Pc)Tb(TNP)] (1) was synthesized and characterized by single crystal X-ray diffraction. The magnetic property of the complex was studied.

A useful strategy for ratiometric fluorescent detecting of Ag+ is demonstrated. Upon selective binding of Ag+ to a BODIPY-porphyrin dyad (1), the synergistic coupling of two functions, namely the suppressing of FRET from BODIPY donor to porphyrin acceptor and the fluorescence quenching of porphyrin acceptor, leads to exceptionally large changes in the intensity ratio of two distinct emissions (F513/F654) which allow for the ratiometric detecting of Ag+ with excellent sensitivity in solution and living cells.

•Three homoleptic bis.(phthalocyaninato) rare earth complexes with eight bulky groups have been synthesized and characterized.•Their molecular structures have been determined by single crystal X-ray diffraction analysis.•Electrochemical properties illuminate the electron-withdrawing nature of 2,6-dimethylphenoxy groups in the double-deckers.Homoleptic bis(phthalocyaninato) rare earth complexes MIII[Pc(β-DMPO)8]2 [Pc(β-DMPO)8 = 2, 3, 9, 10, 16, 17, 23, 24-octakis(2,6-dimethylphenoxy) phthalocyaninate; M = Pr, Nd and Sm] have been synthesized and characterized by a series of spectroscopic methods including matrix-assisted laser desorption/ionization time of flight mass spectrometry, nuclear magnetic resonance spectrum, electronic absorption and infrared spectroscopy. Their molecular structures have been determined by single crystal X-ray diffraction analysis and electrochemical properties studied by cyclic voltammetry. The electrochemical studies illuminate the electron-withdrawing nature of these substituents in the double-deckers. Density functional theory (DFT) calculations are carried out to further clarify the electron transition nature and orbital information. Based on the structural, spectroscopic, electrochemical and theoretical studies, we found that the substitution effect as well as the size of the metal centers altered the molecular and electronic structures significantly.

•A novel hybrid dyad [HYIII(Pc)(Por)]-C60 was designed and synthesized.•The steady-state and transient absorption spectra were analyzed.•A photoinduced charge-separated state [HY(Pc)(Por)]+-(C60)− was obtained.A novel mixed (phthalocyaninato)(porphyrinato) yttrium(III) double-decker complex with a C60 chromophore covalently linked at the porphyrin ligand by phenyl ether linkage has been designed and synthesized. The photophysical properties of this novel dyad containing the C60 and mixed (phthalocyaninato)(porphyrinato) yttrium(III) double-decker components were investigated by steady-state and transient spectroscopic methods. Comparative studies over the electronic absorption spectra document that there is no considerable electronic interaction between the C60 and mixed (phthalocyaninato)(porphyrinato) yttrium(III) double-decker components in the ground state. Time-resolved absorption spectra of this dyad reveal a photoinduced electron transfer from the {HY[Pc(α-OC4H9)8](Por)} moiety to the C60 moiety upon irradiation at 400 nm, which excites both of the components, resulting in a charge-separated state with a lifetime longer than 1 ns.A novel mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complex covalently linked with C60 chromophore at the para position of one meso-phenyl group of the porphyrin ligand by phenyl ether linkage has been designed and synthesized. A photoinduced electron transfer from the {HY[Pc(α-OC4H9)8](Por)} unit to the C60 moiety occurs upon irradiation at 400 nm, which excites both C60 and {HY[Pc(α-OC4H9)8](Por)} components, resulting in a charge-separated state with a lifetime longer than 1 ns.

An intrinsic chiral dinaphthylporphyrin with C2 symmetry, namely [5,15-trans-bis(2-hydroxynaphthyl)-10-phenyl-20-(4-hydroxyphenyl)porphyrinato]zinc(ІІ) (ZnDNP), has been designed and synthesized. The molecular structure of ZnDNP was determined by single crystal X-ray diffraction analysis. Resolution of the racemic mixture was achieved with chiral HPLC technique. In particular, the stereostructures of the enantiomers and the specific interactions between the chiral meso-dinaphthylporphyrin with l-Phe-OMe were elucidated in the solid state by single-crystal X-ray diffraction analysis.An intrinsic chiral dinaphthylporphyrin with C2 symmetry has been synthesized and resolved to pure enantiomers. The stereochemistry has been studied by single-crystal X-ray diffraction analysis.

A C1-symmerical meso-substituted ABCD-type porphyrin, [5-phenyl-10-(2-hydroxynaphthyl)-15-(4-hydroxyphenyl)porphyrinato]zinc(II) (1), has been synthesized and characterized. The molecular structure of 1 has been determined by single-crystal X-ray diffraction analysis. The complex 1 crystallizes in a triclinic system with one pair of enantiomeric molecules per unit cell. Resolution of the racemic mixture has been achieved by chiral HPLC techniques. In particular, the absolute configurations of the enantiomers have been assigned from NMR spectroscopic analysis with l-Phe-OMe as the chiral solvating agent (CSA). The assignments have also been unambiguously confirmed by single-crystal X-ray diffraction analysis. The present results suggest that the CSA–NMR anisotropy strategy is applicable for the stereochemistry determination of chiral host–guest complexes with multiple intermolecular interactions. In addition, the multiple intermolecular interactions between the enantiomerically pure porphyrin S-1 and l-Phe-OMe are proved in the solid state by single-crystal X-ray diffraction analysis.

A series of four mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes (Pc)M[Por(Fc)2] [Pc = phthalocyaninate; Por(Fc)2 = 5,15-di(ferrocenyl)-porphyrinate; M = Eu (1), Y (2), Ho (3), Lu (4)] and their europium(III) triple-decker counterpart (Pc)Eu(Pc)Eu[Por(Fc)2] (5), each with two ferrocenyl units at the meso-positions of their porphyrin ligands, have been designed and prepared. The double- and triple-decker complexes 1–5 were characterized by elemental analysis and various spectroscopic methods. The molecular structures of two double-deckers 1 and 4 were also determined by single-crystal X-ray diffraction analysis. Electrochemical studies of these novel sandwich complexes revealed two consecutive ferrocene-based one-electron oxidation waves, suggesting the effective electronic coupling between the two ferrocenyl units. Nevertheless, the separation between the two consecutive ferrocene-based oxidation waves increases from 1 to 4, along with the decrease of rare earth ionic radius, indicating the effect of rare earth size on tuning the coupling between the two ferrocenyl units. Furthermore, the splitting between the two ferrocene-based one-electron oxidations for triple-decker 5 is even smaller than that for 1, showing that the electronic interaction between the two ferrocene centers can also be tuned through changing the linking sandwich framework from double-decker to triple-decker. For further understanding of the electronic coupling between ferrocenyl groups, DFT calculation is carried out to clarify the electronic delocalization and the molecular orbital distribution in these double-decker complexes.

Density functional theory calculations have been carried out on the subtriazaporphyrin skeletons, an excellent prototype for investigating the dipolar/octupolar contribution to the second-order nonlinear optical (second-order NLO) activity, revealing the size effect and clarifying the nature of the limit when expanding the conjugated system is employed to improve the hyper-Rayleigh scattering response coefficient (βHRS). The octupolar and dipolar contributions are theoretically separated, rendering it possible to control the dipolar/octupolar second-order NLO contribution ratio by changing the number and orientation of the peripheral fused benzene moieties. In addition, both the dispersion and solvent effect were also revealed to lead to the enhancement of βHRS.

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were carried out to simulate the molecular and electronic structures together with the electronic absorption spectra of a series of peripheral methyloxy/methoxycarbonyl substituented phthalocyanines M[Pc(β-OMe)2n(β-COOMe)8−2n] (M = 2H, Zn; n = 0, 1, 2, 3, and 4). Fragment charge distribution and electrostatic potential analysis indicate that the presence of electron-withdrawing and -donation groups leads to the redistribution of charges and obvious polarization effects to the unsymmetrical phthalocyanine series. Peripheral methyloxy/methoxycarbonyl groups introduced onto phthalocyanine ring were revealed to destroy the degeneracy of LUMOs, resulting in significant Q-band splitting for the unsymmetrical phthalocyanine compounds. In addition, metal-free and zinc phthalocyanine compounds display similar electronic structures and absorptions due to the almost none contribution of the zinc atom or inner hydrogens to the frontier molecular orbitals. The microscopic mechanism of the UV–Vis spectra has been clarified on the basis of multi-band photon-induced electron transference. These theoretical studies would be helpful for the molecular design of novel unsymmetrical phthalocyanines.Graphical abstractThe structure–property relationships of a series of peripheral methyloxy/methoxycarbonyl substituented phthalocyanines are calculated using DFT and TDDFT theory. The molecular and electronic structures, fragment charge distribution and electrostatic potentials, and photon-induced electron transference and microscopic mechanism of UV–Vis spectra are studied. The substituent effects change with the number and position of the substituents.Highlights► The presence of peripheral electron-withdrawing and donation groups results in the charge redistribution and obvious polarization effects. ► Metal-free and zinc phthalocyanine compounds display similar electronic structures and absorptions. ► The unsymmetrical phthalocyanines display significant Q-band splitting. ► The substituent effects change with the number and position of the substituents.

Solution-processed organic-inorganic hybrid bulk heterojunction solar cells with the capability of broadband solar photon harvesting over the ultraviolet-visible-near-infrared spectral range are developed. A series of mixed (porphyrinato)(phthalocyaninato) rare-earth double-decker complexes, [MIIIH(TClPP){Pc(α-OC4H9)8}] (1–7; M = Y, Sm, Eu, Tb, Dy, Ho, Lu; TClPP = meso-tetrakis(4-chlorophenyl)porphyrinate; Pc(α-OC4H9)8 = 1,4,8,11,15,18,22,25-octakis(1-butyloxy)phthalocyaninate) and [YIII(TClPP)(Pc)] (8, Pc = unsubstituted phthalocyaninate), along with a heteroleptic bis(phthalocyaninato) yttrium double-decker complex [YIIIH(Pc){Pc(α-OC4H9)8}] (9), are synthesized and utilized as broadband absorbers and electron donors (D), whereas N,N′-bis(1-ethylhexyl)-3,4:9,10-perylenebis(dicarbox-imide) (PDI) or [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) is adopted as primary electron acceptor (A1). For suppressing the fatal back charge transfer at D/A1 interface, the D:A1 blend is fabricated within an in situ formed cheap inorganic network of nanoporous TiOx, which can act as a secondary electron acceptor (A2). For characterization of these structures, steady state spectroscopy, fluorescence dynamics, atomic force microscopy, current–voltage characteristics, and photoelectrical properties of the active materials or devices are investigated. Solar cells utilizing PDI as the primary acceptor show higher values in open circuit voltage, fill factor, and power conversion efficiency over those cells using PCBM as the primary acceptor. With a cell area of 0.36 cm2, good efficiencies of up to 0.82% are achieved by the aforementioned double-decker complex:PDI:TiOx blends under 1-sun air mass 1.5 global illumination. These results conclude that double-decker bis(tetrapyrrole) complexes are promising photovoltaic materials with tunable absorption and photophysical properties.

The synthesis of peripherally octa-substituted phthalocyanine compounds with eight strong electron-withdrawing hexylsulfonyl groups was systematically studied. Three new phthalocyanines M[Pc(SO2C6H13)8] [Pc(SO2C6H13)8 = 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyaninate; M = 2H (1), Cu (2), Zn (3)] were synthesized via direct cyclic tetramerization of 4,5-di(hexylsulfonyl)phthalonitrile or through a diiminoisoindoline intermediate. Compounds 1–3 could alternatively be prepared by oxidation of the hexylthio substituents in corresponding 2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine compounds M[Pc(SC6H13)8] (M = 2H, Cu, Zn) with m-chloroperbenzoic acid. They were fully characterized by elemental analysis and a series of spectroscopic methods. Their electrochemistry was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Density function theory (DFT) calculations were conducted to study the effect of the strong electron-withdrawing groups on the electronic structure of the phthalocyanine molecules. Particularly, the first reduction potentials in the range −0.30∼−0.04 V vs. the saturated calomel electrode (SCE) for 1–3 reveal their n-type semiconducting nature. The current–voltage characteristics of their aggregates demonstrate the good semiconducting properties especially for 1 and 2 with the conductivity value of 5.24 × 10−4 and 2.73 × 10−4 S m−1, respectively.

The conformational effects on the frontier molecular orbital energy and stability for reduced, neutral, and oxidized bis(phthalocyaninato) lanthanum double-deckers have been revealed on the basis of density functional theory calculations. Calculation results indicate that the frontier orbital coupling degree changes along with the molecular conformation of the double-decker compound, first decreasing along with the increase of rotation angle β from 0 to 20° and then increasing along with the increase of rotation angle β from 20 to 45°. In addition, the stability for the three forms of double-decker changes in the same order, but first increasing and then decreasing along with the change of the rotation angle β in the range of 0 to 45° with a rotation energy barrier of (31.3 ± 3.1) kJ mol−1 at 20°. This reveals that the rotation of the two phthalocyanine rings for the reduced, neutral, and oxidized bis(phthalocyaninato) lanthanum double-deckers are able to occur at room temperature. Nevertheless, the superior coordination reaction activity of the neutral bis(phthalocyaninato) lanthanum double-decker complex over their reduced form in forming sandwich-type tris(phthalocyaninato) lanthanum triple-decker compounds has also been clearly clarified on the basis of comparative calculations on the Fukui function of [La(Pc)2] and [La(Pc)2]− using the DFT method. Fukui function analysis reveals the reaction center of the 18-electron-π-conjugated core in the bis(phthalocyaninato) lanthanum double-decker molecule against both electrophilic and radical attack. Nevertheless, the larger global chemical softness (S) for the neutral [La(Pc)2] than the reduced form [La(Pc)2]− indicates the higher reaction activity of the former form over the latter one. This explains well the experimental findings that only the neutral instead of the reduced form of bis(tetrapyrrole) rare earth double-decker complexes, containing at least one phthalocyanine ligand, could be employed as starting materials towards the preparation of tris(tetrapyrrole) rare earth triple-decker complexes by a solution process.

Treatment of sandwich-type mixed (phthalocyaninato)(porphyrinato) metal complex [HEuIII{Pc(α-3-OC5H11)4}{TriBPP(NH2)}] (3) [Pc(α-3-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)-phthalocyaninate, TriBPP(NH2) = 5,10,15-tris(4-tert-butylphenyl)-20-(4-aminophenyl)porphyrinate] with N-n-butyl-1,6,7,12-tetra(4-tert-butylphenoxyl)perylene-3,4-dicarboxylate anhydride-9,10-dicarboxylate imide (2) in the presence of imidazole in toluene afforded the novel perylene diimide-appended mixed (phthalocyaninato)(porphyrinato) europium(III) double-decker complex (5). Porphyrin–PDI dyad 4 was also obtained by similar method. The electronic absorption spectroscopic and electrochemical properties of PDI-appended double-decker 5 and the model compounds 2, 3, and 4 were studied, the results indicated that there was no considerable ground-state interaction between the double-decker unit and the PDI unit in 5. The fluorescence measurements revealed that the emission of PDI unit was effectively quenched by the double-decker unit, suggesting remarkable intramolecular interaction in 5 under excited state.A novel phthalocyanine–porphyrin–PDI array containing a sandwich-type mixed (phthalocyaninato)(porphyrinato) europium(III) double-decker core and a PDI modifier was designed and synthesized. The steady-state electronic absorption and electrochemical studies indicated that there was no ground-state interaction between the double-decker unit and the PDI unit. The fluorescence measurements revealed that the emission of PDI unit was remarkably quenched by the double-decker unit, suggesting considerable intramolecular interaction under excited state.Highlights► A PDI-appended mixed Eu(Pc)(Por) double-decker complex was synthesized. ► The electronic absorption and electrochemical properties were studied. Interaction between the double-decker unit and the PDI unit was not observed at ground state. ► The emission of PDI unit was quenched by the double-decker unit. Considerable intramolecular interaction exists at excited state.

The infrared spectroscopic data for a series of three 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyanine compounds with eight strong electron-withdrawing hexylsulfonyl groups at the peripheral positions M[Pc(SO2C6H13)8] [M = 2H (1), Cu (2), Zn (3)] have been collected with resolution of 2 cm−1. The infrared spectra of compounds 1 and 3 have also been calculated at the density functional B3LYP level. Detailed assignments of the vibrational bands in the IR spectra have been achieved through comparison of the experimental and calculated results. The influence of the metalation and the substitution of eight strong electron-withdrawing alkylsulfonyl groups on the IR characteristics of the phthalocyanines has been discussed based on the comparison between corresponding data.

The molecular and electronic structures together with the electronic absorption spectra of a series of metal free meso-ferrocenylporphyrins, namely 5-ferrocenylporphyrin (1), 5,10-diferrocenylporphyrin (2), 5,15-diferrocenylporphyrin (3), 5,10,15-triferrocenylporphyrin (4), and 5,10,15,20-tetraferrocenylporphyrin (5) have been studied with the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. For the purpose of comparative studies, metal free porphyrin without any ferrocenyl group (0) and isolated ferrocene (6) were also calculated. The effects of the number and position of meso-attached ferrocenyl substituents on their molecular and electronic structures, atomic charges, molecular orbitals, and electronic absorption spectra of 1–5 were systematically investigated. The orbital coupling is investigated in detail, explaining well the long range coupling of ferrocenyl substituents connected via porphyrin core and the systematic change in the electronic absorption spectra of porphyrin compounds.Graphical abstractThe electronic communication between meso-ferrocenyl substituents and porphyrin core, as well as the long range orbital coupling of the meso-ferrocenyl substituents, are explained using DFT and TDDFT theory.Research highlights▶ The molecular and electronic structures together with the electronic absorption spectra of a series of metal free meso-ferrocenylporphyrins, namely 5-ferrocenylporphyrin (1), 5,10-diferrocenylporphyrin (2), 5,15-diferrocenylporphyrin (3), 5,10,15-triferrocenylporphyrin (4), and 5,10,15,20-tetraferrocenylporphyrin (5) have been studied with the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. For the purpose of comparative studies, metal free porphyrin without any ferrocenyl group (0) and isolated ferrocene (6) were also calculated. The effects of the number and position of meso-attached ferrocenyl substituents on their molecular and electronic structures, atomic charges, molecular orbitals, and electronic absorption spectra of 1–5 were systematically investigated. The orbital coupling is investigated in detail, explaining well the long range coupling of ferrocenyl substituents connected via porphyrin core and the systematic change in the electronic absorption spectra of porphyrin compounds.

Two new coordination polymers [Zn2L(2,2′-bpy)]n∙(H2O)2n (1) and [Zn2L(phen)]n∙(H2O)2n (2) have been assembled from a semirigid multicarboxylate ligand 3,3′-(1,3-phenylenebis(oxy))diphthalic acid (H4L) with the help of 2,2′-bipyridine (2,2′-bpy) or 1,10-phenanthroline (phen) as secondary ligand. Single crystal X-ray diffraction analysis reveals that complex 1 crystallizes in the space group C2/c and displays a one-dimensional (1D) chain structure constructed from 2,2′-bpy and L ligand, which further forms a two-dimensional (2D) plane via intermolecular π–π interactions. Compound 2 belongs to the space group P1¯ and features a 1D Δ- and Λ-typed chiral chain configuration despite the racemic nature for the whole complex. The neighboring chains with the same chirality are further stacked into a 2D ΔΔΔ- or ΛΛΛ-typed supramolecular structure via intermolecular π–π interactions because of the chiral recognition mechanism. Photophysical properties over complexes 1 and 2 have been comparatively investigated, revealing the effect of secondary ligand on the luminescent properties of these two complexes.

The synthesis of peripherally octa-substituted phthalocyanine compounds with eight strong electron-withdrawing hexylsulfonyl groups was systematically studied. Three new phthalocyanines M[Pc(SO2C6H13)8] [Pc(SO2C6H13)8 = 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyaninate; M = 2H (1), Cu (2), Zn (3)] were synthesized via direct cyclic tetramerization of 4,5-di(hexylsulfonyl)phthalonitrile or through a diiminoisoindoline intermediate. Compounds 1–3 could alternatively be prepared by oxidation of the hexylthio substituents in corresponding 2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine compounds M[Pc(SC6H13)8] (M = 2H, Cu, Zn) with m-chloroperbenzoic acid. They were fully characterized by elemental analysis and a series of spectroscopic methods. Their electrochemistry was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Density function theory (DFT) calculations were conducted to study the effect of the strong electron-withdrawing groups on the electronic structure of the phthalocyanine molecules. Particularly, the first reduction potentials in the range −0.30∼−0.04 V vs. the saturated calomel electrode (SCE) for 1–3 reveal their n-type semiconducting nature. The current–voltage characteristics of their aggregates demonstrate the good semiconducting properties especially for 1 and 2 with the conductivity value of 5.24 × 10−4 and 2.73 × 10−4 S m−1, respectively.

Solution-processed organic-inorganic hybrid bulk heterojunction solar cells with the capability of broadband solar photon harvesting over the ultraviolet-visible-near-infrared spectral range are developed. A series of mixed (porphyrinato)(phthalocyaninato) rare-earth double-decker complexes, [MIIIH(TClPP){Pc(α-OC4H9)8}] (1–7; M = Y, Sm, Eu, Tb, Dy, Ho, Lu; TClPP = meso-tetrakis(4-chlorophenyl)porphyrinate; Pc(α-OC4H9)8 = 1,4,8,11,15,18,22,25-octakis(1-butyloxy)phthalocyaninate) and [YIII(TClPP)(Pc)] (8, Pc = unsubstituted phthalocyaninate), along with a heteroleptic bis(phthalocyaninato) yttrium double-decker complex [YIIIH(Pc){Pc(α-OC4H9)8}] (9), are synthesized and utilized as broadband absorbers and electron donors (D), whereas N,N′-bis(1-ethylhexyl)-3,4:9,10-perylenebis(dicarbox-imide) (PDI) or [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) is adopted as primary electron acceptor (A1). For suppressing the fatal back charge transfer at D/A1 interface, the D:A1 blend is fabricated within an in situ formed cheap inorganic network of nanoporous TiOx, which can act as a secondary electron acceptor (A2). For characterization of these structures, steady state spectroscopy, fluorescence dynamics, atomic force microscopy, current–voltage characteristics, and photoelectrical properties of the active materials or devices are investigated. Solar cells utilizing PDI as the primary acceptor show higher values in open circuit voltage, fill factor, and power conversion efficiency over those cells using PCBM as the primary acceptor. With a cell area of 0.36 cm2, good efficiencies of up to 0.82% are achieved by the aforementioned double-decker complex:PDI:TiOx blends under 1-sun air mass 1.5 global illumination. These results conclude that double-decker bis(tetrapyrrole) complexes are promising photovoltaic materials with tunable absorption and photophysical properties.

The conformational effects on the frontier molecular orbital energy and stability for reduced, neutral, and oxidized bis(phthalocyaninato) lanthanum double-deckers have been revealed on the basis of density functional theory calculations. Calculation results indicate that the frontier orbital coupling degree changes along with the molecular conformation of the double-decker compound, first decreasing along with the increase of rotation angle β from 0 to 20° and then increasing along with the increase of rotation angle β from 20 to 45°. In addition, the stability for the three forms of double-decker changes in the same order, but first increasing and then decreasing along with the change of the rotation angle β in the range of 0 to 45° with a rotation energy barrier of (31.3 ± 3.1) kJ mol−1 at 20°. This reveals that the rotation of the two phthalocyanine rings for the reduced, neutral, and oxidized bis(phthalocyaninato) lanthanum double-deckers are able to occur at room temperature. Nevertheless, the superior coordination reaction activity of the neutral bis(phthalocyaninato) lanthanum double-decker complex over their reduced form in forming sandwich-type tris(phthalocyaninato) lanthanum triple-decker compounds has also been clearly clarified on the basis of comparative calculations on the Fukui function of [La(Pc)2] and [La(Pc)2]− using the DFT method. Fukui function analysis reveals the reaction center of the 18-electron-π-conjugated core in the bis(phthalocyaninato) lanthanum double-decker molecule against both electrophilic and radical attack. Nevertheless, the larger global chemical softness (S) for the neutral [La(Pc)2] than the reduced form [La(Pc)2]− indicates the higher reaction activity of the former form over the latter one. This explains well the experimental findings that only the neutral instead of the reduced form of bis(tetrapyrrole) rare earth double-decker complexes, containing at least one phthalocyanine ligand, could be employed as starting materials towards the preparation of tris(tetrapyrrole) rare earth triple-decker complexes by a solution process.