Co-reporter:Jianyong Yuan, Yizhong Yuan, Xiaohui Tian, Yidan Liu, and Jinyu Sun
The Journal of Physical Chemistry C April 13, 2017 Volume 121(Issue 14) pp:8091-8091
Publication Date(Web):March 8, 2017
DOI:10.1021/acs.jpcc.7b01360
Systematic comparisons among the oxazinone, quinazoline, and difluoroboron series on optical absorption and fluorescence emission properties have been made. Weaker electron donor–acceptor (D–A) pairs in both the oxazinone and quinazoline series bring about the slight red shifts of absorption spectra, whereas they significantly promote the fluorescence intensities of the oxazinone series but bathochromically shift the maximum emission wavelengths of the quinazoline series. Intrinsically, the charge-transfer (CT) modes govern the electron excitation/de-excitation processes in both the oxazinone and quinazoline series, but with respective different CT features, i.e., the interfragment CT mode for the oxazinone series versus the intrafragment CT mode for the quinazoline series. In the difluoroboron series, Oxa-Cl-OCH3-BF2 undergoes a change of transition mode from the local excitation to the CT de-excitation, whereas a large variation of CT compositions can be observed in Qui-Cl-OCH3-BF2. Experimentally, Oxa-Cl-OCH3-BF2 exhibits higher fluorescence quantum yield, favorable thermo- and photostability, stronger fluorescence intensity, and appropriately large Stokes shift, whereas theoretically, Qui-Cl-OCH3-BF2 benefiting from both the difluoroboron and quinazoline moieties is also promising to be a good fluorescent dye. The motif of combining oxazinone/quinazoline and difluoroboron moieties is believed to improve the prototypical architectures of oxazinone and quinazoline dyes.
Co-reporter:Jin Liu;Xiaohui Tian;Jinyu Sun ;Yizhong Yuan
Journal of Applied Polymer Science 2016 Volume 133( Issue 35) pp:
Publication Date(Web):
DOI:10.1002/app.43843
ABSTRACT
Poly(methyl methacrylate-co-butyl methacrylate) [P(MMA-co-BMA)] nanoparticles were synthesized via emulsion polymerization, and incorporated into natural rubber (NR) by latex compounding. Monodispersed, core-shell P(MMA-co-BMA)/casein nanoparticles (abbreviated as PMBMA-CA) were produced with casein (CA) as surfactant. The chemical structure of P(MMA-co-BMA) copolymers were confirmed by 1H-NMR and FTIR analyses. Transmission electron microscopy demonstrated the core–shell structure of PMBMA-CA, and PMBMA-CA homogenously distributed around NR particles, indicating the interaction between PMBMA-CA and NR. As a result, the tensile strength and modulus of NR/PMBMA-CA films were significantly enhanced. The tensile strength was increased by 100% with 10% copolymer addition, when the molar ratio of MMA:BMA was 8:2. In addition, scanning electron microscopy and atomic force microscopy results presented that the NR/PMBMA-CA films exhibited smooth surfaces with low roughness, and PMBMA-CA was compatible with NR. FTIR-ATR analyses also suggested fewer PMBMA-CA nanoparticles migrated out of NR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43843.
Co-reporter:Shuyi Wang;Xiaohui Tian;Jinyu Sun;Jin Liu ;Junchao Duan
Journal of Applied Polymer Science 2016 Volume 133( Issue 38) pp:
Publication Date(Web):
DOI:10.1002/app.43961
ABSTRACT
Na-montmorillonite/polyethyleneimine-g-poly(methyl methacrylate) (Na-MMT/PEI-g-PMMA) nanocomposite latexes were prepared by soap-free emulsion polymerization in the aqueous suspension of Na-MMT. The exfoliated morphology of the nanocomposites was confirmed by XRD and TEM. With the aim of improving morphology and mechanical properties of natural rubber latex (NRL) films, the synthesized Na-MMT/PEI-g-PMMA nanocomposites were mixed with NRL by latex compounding technology. The results of SEM and AFM analysis showed that the surface of NRL/Na-MMT/PEI-g-PMMA film was smoother and denser than that of pristine NRL film while Na-MMT was dispersed uniformly on the fracture surface of the modified films, which suggested the good compatibility between NRL and Na-MMT/PEI-g-PMMA. The tensile strength of NRL/Na-MMT/PEI-g-PMMA films was increased greatly by 85% with 10 phr Na-MMT/PEI-g-PMMA when Na-MMT content was 3 wt % and the elongation at break also increased from 930% to 1073% at the same time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43961.
Co-reporter:Chao Wang, Yizhong Yuan, Xiaohui Tian, Jinyu Sun, Jianyong Yuan
Computational and Theoretical Chemistry 2016 Volume 1085() pp:40-45
Publication Date(Web):1 June 2016
DOI:10.1016/j.comptc.2016.04.006
•TDDFT provides good results close to SAC-CI level.•Exact exchange effects on second hyperpolarizabilities.•Functional tuning of LRC functionals.TDDFT calculations are used to discuss the effects of the exact exchange (Ex) on the evaluation of second hyperpolarizabilities (γyyyy) of streptocyanines (3–9 carbons). The results confirm that TDDFT calculations are reliable on the reproduction of the first excitation energies (E01) compared with experiments (within 0.3 eV deviations). The sum-over-states (SOS) calculations based on TDDFT suggest that the percentages of Ex determines the γyyyy. The nonlinear optical (NLO) active region of streptocyanines is the π-bridge conjugation where the bond length is between 2 and 3 au. Within this area, the higher the percentage of Ex is, the lower the γyyyy is (γyyyy is normally negative for streptocyanines). The γyyyy can be decomposed into T and N contributions according to the three-level SOS method. The decomposition shows that the T term significantly decreases with the increasing percentages of Ex, while N term gradually increases. Therefore, hybrid generalized gradient approximation (hGGA), hybrid meta-generalized gradient approximation (hybrid meta-GGA) and long-range corrected (LRC) functionals tend to overestimate γyyyy. The functional tuning process can improve the results due to the decreasing of ω. This means the deviation of γyyyy do NOT corresponds to the delocalization error (DE). Consequently, the pure GGA, pure meta-GGA, and LRC with small ω can give qualitative correct results.
Co-reporter:Chao Wang;Yizhong Yuan;Xiaohui Tian;Jianyong Yuan;Jinyu Sun
Structural Chemistry 2016 Volume 27( Issue 4) pp:1211-1220
Publication Date(Web):2016 August
DOI:10.1007/s11224-016-0746-5
The structure–properties relationship of heterocyclic polymethines on the all-optical switching processing (AOSP) is studied by CC2 method. In particular, the excitation energies of the first and second excited states (Ege and Ege′) and the corresponding ratio (Ree′ = Ege′/Ege, energy window width) are evaluated. The comparable energy gap between HOMO and HOMO − 1 (π type) and between LUMO and LUMO + 1 (π* type) is the key in keeping Ree′ large. Moreover, only a significant increase of such energy gap can result in the increase in Ree′ because the energy gap is a poor description of excitation energy. The results show that the heavy heteroatoms decrease the Ege and Ege′ as expected compared to light atoms such as carbon. For five-membered heterocyclic polymethines and their derivatives (two heteroatoms in total), the Ree′ is stable around 1.7 reflecting the nature of this system: The additional heteroatoms have little effects on the width of energy window. In the case of six-membered heterocyclic polymethines and their derivatives, the decrease in excitation energy is more effective compared to the former due to the relative large effective length of the end group, which can thus help avoiding the symmetry breaking. The effect of heteroatoms on Ree′ is clear that it helps keeping the energy window open compared to carbon atom. The heavier the heteroatom is, the higher Ree′ value will be when it is on the ortho position. Consequently, at least one heteroatom is necessary on the design of polymethines for AOSP application.
Co-reporter:Jianyong Yuan
The Journal of Physical Chemistry C 2016 Volume 120(Issue 27) pp:14840-14853
Publication Date(Web):June 10, 2016
DOI:10.1021/acs.jpcc.6b04849
A new type of prototypical biphotochromic switches combining spirooxazine and fulgide has been synthesized, and their nonlinear optical (NLO) responses have been theoretically studied on the basis of density functional theory (DFT). Our DFT calculations show that the introduction of a fulgide fragment (E and C) into the spirooxazine host can largely enhance the static second- and third-order NLO responses. Moreover, the photoisomerization of spirooxazine derivatives (SO-E and SO-C) brings forth a pronounced change in the geometry accompanied by the formation of a larger π-conjugated system, and thus the corresponding merocyanine derivatives (PMC-E and PMC-C) obtain ∼3.5-times enhancement of static second- and third-order NLO responses. Nevertheless, the difference in NLO responses between the E-form series (SO-E and PMC-E) and the C-form series (SO-C and PMC-C), respectively, is not substantial, which means the fulgide fragment in the prototypical biphotochromic system does not considerably differentiate the corresponding optical nonlinearities. To separate well the NLO responses of four states in our prototype, we further propose a structural modification strategy by introducing the furan moiety (2-vinylfuran) into the π-bridge, and the corresponding NLO performances from DFT results finally meet our demands, indicating that such a revised biphotochromic system based on our prototype is a fascinating choice for the architecture of multistate NLO switches.
Co-reporter:Chao Wang, Yizhong Yuan, Xiaohui Tian, Rebecca L. Gieseking, Jinyu Sun
Journal of Molecular Graphics and Modelling 2016 Volume 64() pp:1-10
Publication Date(Web):March 2016
DOI:10.1016/j.jmgm.2015.12.005
•Combined topology analysis NCI/ELF.•Different hydrogen binding modes of halides and Y-shaped anions.•Design of potential carbonylchromium-based urea-like hosts based on IR-shifting signals.One of the major challenges in anion recognition is to design hosts that can be used to distinguish between anions of different shapes. Urea-based molecules are widely used in anion recognition because the pair of -NH groups acts as an electron acceptor. Although these hosts can bind to both spherical anions (halides) and Y-shaped anions (oxoanions), experimental evidence to date does not provide a clear picture of what differences in the nature of the hydrogen bonding interactions could be used to distinguish between anions of different shapes. Here, we use several computational topology analyses to study the non-covalent interactions between Cr(CO)3-based organometallic urea-like hosts and halides and Y-shaped oxoanions. Our results suggest that the F− and AcO− anions are recognized experimentally due to a combination of strong interaction and large infrared (IR) shifts upon complexation, verifying the remarkable IR-reporting ability of the Cr(CO)3 moiety and its potential applications in anion recognition. The lone pairs of the oxygen atom in Y-shaped oxoanions directly interact with the -NH groups of the hosts, while all the shell electrons of the halides participate as a group in the interaction; however, the relative contributions of electrostatic and charge-transfer interactions are quite similar for the two types of anions. This insight into the nature of the anion-host interactions can be used to provide guidance for the design of hosts that differentiate between anions.The carbonylchromium-based urea-like hosts show the potential of recognition of halides and Y-shaped anions based on the shifting of the CO bands in the IR spectrum.
Co-reporter:Lei Zhang, Yi-Zhong Yuan, Xiao-Hui Tian, Jin-Yu Sun
Chinese Chemical Letters 2015 Volume 26(Issue 9) pp:1133-1136
Publication Date(Web):September 2015
DOI:10.1016/j.cclet.2015.05.027
A new type of diacetylene monomer which includes a biphenylcarboxylic acid group as its head group is synthesized. Polymerization was performed after monomer form spherical vesicle by self-assembly in the water. The polydiacetylene displayed completely thermochromic color change in the range of 20–95 °C owing to the presence of strong π–π interaction caused by biphenyl group and hydrogen bonding between head group.A new type of polydiacetylene, which derived from biphenyl-linked diacetylene, is developed. This new polydiacetylene displays a completely reversible blue-to-red color transition upon thermal stress.
Co-reporter:Zhaojun Zheng;Xiaohui Tian;Jinyu Sun;Yizhong Yuan;Bing Xie
Polymer Science, Series A 2015 Volume 57( Issue 5) pp:613-621
Publication Date(Web):2015 September
DOI:10.1134/S0965545X15050181
Poly(methyl methacrylate-co-2-ethylhexyl methacrylate) copolymers with 0.6–49.2 mol% of 2-ethylhexyl methacrylate were synthesized and blended with natural rubber at three different blend ratios (i.e. 5/95, 10/90, 15/85) on the latex stage. Chemical structure of the copolymer was confirmed by FTIR and 1H NMR spectroscopy. Mechanical strength of the blend (rubber/copolymer) containing 7.76 mol% of 2-ethylhexyl methacrylate showed the higher values than the incompatible blend natural rubber/PMMA. According to water absorption and ATR-FTIR measurements, the amount of dispersed particles of obtained blends on the surface decreases sharply compared to rubber/PMMA blend. Scanning electron microscopy and atomic force microscopy also showed that surface and cross-section morphologies of the studied were more homogeneous than those of incompatible blend. The miscibility of studied blend was further reflected by DSC analysis.
Co-reporter:Haitao Sun, Xiaohui Tian, Jochen Autschbach, Yizhong Yuan, Jinyu Sun, Xin Liu, Chuan Chen and Huijun Cao
Journal of Materials Chemistry A 2013 vol. 1(Issue 36) pp:5779-5790
Publication Date(Web):02 Jul 2013
DOI:10.1039/C3TC31131G
A new type of organic photochromic spirooxazine has been synthesized, incorporating increasing numbers of thiophene units by vinyl bridges. These compounds exhibit tunable photochromic properties that are sensitive to low-energy visible light compared with traditional UV. Furthermore, the ring-opening mechanism is put in relation to the interaction of fragment molecular orbitals. The result shows that the effective excitation with significant intensity is centred mainly on the naphthoxazine part and vinyl thiophene plays a crucial role in the photochemical and photophysical process. Density functional calculations are performed to rationalize the “on and off” switching nonlinear optical behaviors of compounds, showing the potential for applying the materials in nonlinear optical switches.
Co-reporter:Jinyu Sun;Xiaohui Tian;Ping Feng;ShuTing Gong;Yizhong Yuan
Journal of Applied Polymer Science 2013 Volume 129( Issue 5) pp:2404-2410
Publication Date(Web):
DOI:10.1002/app.38963
Abstract
The technique of enzyme treatment on the water-soluble proteins and mechanical properties of natural rubber latex (NRL) films was studied. The main aim was to introduce an enzymic catalysis method to tackle the protein allergy problem in NRL product. The suitable pH value, the temperature, and the best proportion of transglutaminase to deal with NRL were found. The protein spillage of modified NRL films was greatly lower than that of unmodified NRL, and the tensile strength and the elongation at break of the modified NRL films almost had been scarcely changed. The compactness of the NRL films was improved simultaneously. These suggest that the modified NRL can be used as a kind of latex with low-allergy personal barrier products such as surgical gloves. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Chao Wang, Yizhong Yuan, Xiaohui Tian, Jinyu Sun, Hongjuan Shao, Zhenrong Sun
Chemical Physics Letters 2013 Volume 583() pp:185-189
Publication Date(Web):17 September 2013
DOI:10.1016/j.cplett.2013.07.054
•Combining TD-DFT and two-state SOS approach to calculate the static γ.•Providing strategies to enhance χ(3) in non-centrosymmetric cyanine dyes.•Utilizing electron density difference to study the charge transfer properties.The linear and third-order nonlinear optical properties of four polymethine cyanines (PC-1–PC-4) were investigated by UV–visible absorption spectroscopy and degenerate four-wave mixing (DFWM) technique. The second-order hyperpolarizabilities γ of the four chromophores achieve 10−31 esu. The dependence of their third-order optical nonlinearities on the molecular structure was discussed based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations. The calculated second-order hyperpolarizabilities γ well-reproduce the experimental trends. The results show that the third-order optical nonlinearities of the chromophores can be drastically enhanced by bulky heteroatom (such as selenium) with low electro-negativity, or extended π-conjugated terminal group.
Co-reporter:Haitao Sun, Xiaohui Tian, Jun Wang, Jian Zhang, Yizhong Yuan, and Zhen-Rong Sun
The Journal of Physical Chemistry A 2011 Volume 115(Issue 50) pp:14495-14501
Publication Date(Web):October 31, 2011
DOI:10.1021/jp2066452
Studies on the molecular geometries, electronic properties and second-order nonlinearities of a series of mono- and binuclear chromium carbazole complexes: (N-vinylcarbazole)Cr(CO)3 (M1), (N-vinylcarbazole)Cr(CO)2PPh3 (M2), (CO)3Cr(N-vinylcarbazole)Cr(CO)3 (B1), and (CO)3Cr(N-vinylcarbazole)Cr(CO)2PPh3 (B2) were carried out, using the density functional theory (DFT) at the B3LYP//LanL2DZ/6-31G(d) level. The experimental singlet metal-to-ligand charge transfer (1MLCT) spectra of these complexes can also be well simulated and discussed by the time-dependent DFT (TDDFT) at the B3LYP//LanL2DZ/6-311+G(d) level associated with the polarizable continuum model (PCM). The computational results show that an unusual characteristic of chromium carbazole structures is explained in terms of interaction between frontier molecular orbitals of the metal and its ligands. The highest occupied molecular orbitals (HOMOs) of these complexes are composed of a set of distorted degenerated Cr 3d orbitals, whereas the lowest unoccupied molecular orbitals (LUMOs) are predominantly the N-vinylcarbazole ligand π* orbitals. The HOMO–LUMO energy gaps decrease in the order NVC > M1 > B1 > M2 > B2. The considerable coupling between the carbazole and (CO)3 in M1 creates an asymmetric environment about the chromium atom, leading to modest second-order responses. The PPh3 ligand is acting as a donor which increases the donating strength of the dπ orbitals in chromium carbazole species, resulting in the large electronic asymmetry in M2. As for the binuclear chromium carbazole chromophores, a wide-range 1MLCT band and large oscillator strength are found, allowing for the electronic interactions between two metal centers which can be modified by altering the ligand bound to the metals to induce peculiar asymmetry. Essentially, Cr(CO)3 acceptor and Cr(CO)2PPh3 donor units in B2 make significant contribution to the charge-transfer process or NLO responses via conventional push–pull chromophoric architecture.
Co-reporter:Xiaohui Tian, Haitao Sun, Yizhong Yuan, Jiaping Lin, Lixian Liang, Yanchao Che
Tetrahedron 2010 66(48) pp: 9456-9460
Publication Date(Web):
DOI:10.1016/j.tet.2010.09.058
Co-reporter:Xiaohui Tian, Li Song, Yizhong Yuan and Jiaping Lin
Organometallics 2010 Volume 29(Issue 3) pp:509-511
Publication Date(Web):January 5, 2010
DOI:10.1021/om9008263
Two new urea derivatives bearing a tricarbonylchromium moiety showed high selectivity and sensitivity toward carboxylate anions in competitive hydrogen bonding solvents, which can be monitored by the changes of the IR spectrum of the carbonyl groups complexed with the organic metal.
Co-reporter:Chen Hui;Tian Xiaohui;Yuan Yizhong ;Lin Jiaping
Journal of Applied Polymer Science 2008 Volume 107( Issue 6) pp:4076-4081
Publication Date(Web):
DOI:10.1002/app.27553
Abstract
A novel η6-complex of N-allylcarbazole containing chromium tricarbonyl was synthesized. This complex was hydrosilylated with polymethylhydrosiloxane to afford a substituted polymer. Both the complex and the polymer were characterized by classical spectroscopy techniques (FTIR, NMR, and UV–vis), gel permeation chromatography, elemental analysis, and thermal analysis (TGA and DSC). The glass transition temperature of the polymer was found to be above 100°C and its thermal decomposition temperature was above 280°C. The polymer was amorphous in nature and formed excellent homogeneous films of good optical transparency. The third nonlinear optical properties of this polymer film coated on quartz substrate were studied by time-resolved forward degenerate four-wave mixing (DFWM). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yanchao Che, Xiaohui Tian, Hui Chen, Zhenyu Tang and Jiaping Lin
New Journal of Chemistry 2006 vol. 30(Issue 6) pp:883-889
Publication Date(Web):27 Apr 2006
DOI:10.1039/B518346D
Carbazole mono- and bimetallic complexes [(N-ethylcarbazole){Cr(CO)3}2] (3) and [(N-ethylcarbazole)Cr(CO)2L] (L = CO (2) and PPh3 (4)) have been synthesized, and X-ray crystal structure analyses performed for 2 and 4. Each complex possesses spectroscopically intense intraligand (IL) and metal-to-ligand charge-transfer (MLCT) excitations that are well separated in energy. The MLCT bands display a small to moderate negative solvatochromism. The third-order non-linear optical (NLO) properties, measured by the time-resolved forward degenerate four-wave mixing (DFWM) technique in solution at 532 nm, have been studied for these complexes, together with N-ethylcarbazole for comparison. It is found that the third-order NLO response can be tuned by chromium complexation. The molecular second-order hyperpolarizabilities, γ, of the synthesized complexes are determined to be in the order of 10−30 esu and clearly depend on both the nature of the ligand and the extent of chromium tricarbonyl coordination by the carbazole ring. The carbazole-mediated metal–metal electronic interaction existing in 3 is believed to be a possible factor responsible for a large improvement in the non-linearity.
Co-reporter:Xiaohui Tian, Wei Ru, Juhua Zhong, Jiaping Lin, Chenyan Li, Xili Luo
Chemical Physics 2006 Volume 324(2–3) pp:667-673
Publication Date(Web):31 May 2006
DOI:10.1016/j.chemphys.2005.11.034
Abstract
To be useful in elucidating structure–property relationships for the planar fused ring bearing metal π-complexation, the structures of (acenaphthylene)Cr(CO)3 (3) and (acenaphthene)Cr(CO)3 (4) were determined by X-ray crystal analyses, and their nonlinear optical activities investigated by using density functional theory calculations. The title molecules exhibit the intense electronic absorptions characteristic of charge-transfer capability and moreover, the observed negative solvochromicity in the low-energy transition is proposed to be associated with the organometallic modification of the electronic structure. These results are compared with the behavior of the corresponding free ligands, indicating that chromium tricarbonyl complexation can be used to create an unique non-centrosymmetric metal-organic architecture with the more extensive π-delocalization and, therefore, improve the nonlinear optical response.
Co-reporter:Haitao Sun, Xiaohui Tian, Jochen Autschbach, Yizhong Yuan, Jinyu Sun, Xin Liu, Chuan Chen and Huijun Cao
Journal of Materials Chemistry A 2013 - vol. 1(Issue 36) pp:NaN5790-5790
Publication Date(Web):2013/07/02
DOI:10.1039/C3TC31131G
A new type of organic photochromic spirooxazine has been synthesized, incorporating increasing numbers of thiophene units by vinyl bridges. These compounds exhibit tunable photochromic properties that are sensitive to low-energy visible light compared with traditional UV. Furthermore, the ring-opening mechanism is put in relation to the interaction of fragment molecular orbitals. The result shows that the effective excitation with significant intensity is centred mainly on the naphthoxazine part and vinyl thiophene plays a crucial role in the photochemical and photophysical process. Density functional calculations are performed to rationalize the “on and off” switching nonlinear optical behaviors of compounds, showing the potential for applying the materials in nonlinear optical switches.
