WO2 and TiO2 colMds were synthesized by the hydrolysis technique and part of the TiO2 colloid was treated by means of the hydrothermal method. The photochromic performances of the resulting materials obtained via comb...WO2 and TiO2 colMds were synthesized by the hydrolysis technique and part of the TiO2 colloid was treated by means of the hydrothermal method. The photochromic performances of the resulting materials obtained via combining the WO3 colloid with the treated TiO2 colloid and the non-treated TiO2 colloid, respectively, are very different. The TiO2 colloid without hydrothermal treatment can effectively improve the photochromic performance of the WO3colloid. The TiO2 nanoparticles were investigated in detail by XRD, TEM, surface photovohage spectra（SPS） and field-induced surface photovoltage spectrometry（FISPS）. The photochromism mechanism of WO3 colloid is discussed.展开更多
The interfacial behaviors of the non-typical amphiphilic compound p-methylphenylazocalix[4]arene 1 and p-chlorophenylazocalix[4]arene 2 at the air/water interface and photochromism in the Langmuir-Blodgett films were ...The interfacial behaviors of the non-typical amphiphilic compound p-methylphenylazocalix[4]arene 1 and p-chlorophenylazocalix[4]arene 2 at the air/water interface and photochromism in the Langmuir-Blodgett films were studied by surface pressure-area isotherm and UV-Vis spectra. The results indicate that they can form stable monolayers at the air / water interface although they have no hydrophobic alkyl chains, and their LB film underwent reversible trans-cis photoisomerization on UV and daylight illumination.展开更多
A new family of photochromic diarylethene compounds, 1-（2-cyano-l,5-dimethyl- 4-pyrryl）-2-[2-methyl-5-（3-pyridyl）-3-thienyl]perfluorocyclopentene （lo） having an unsymmetrical pyrryl and thienyl substituted hexaf...A new family of photochromic diarylethene compounds, 1-（2-cyano-l,5-dimethyl- 4-pyrryl）-2-[2-methyl-5-（3-pyridyl）-3-thienyl]perfluorocyclopentene （lo） having an unsymmetrical pyrryl and thienyl substituted hexafluorocyclopentene unit, was synthesized and its structure was determined by X-ray analysis. The crystal belongs to triclinic system, space group PI with a = 8.897（7）, b = 10.139（8）, c = 12.361（9） A, α = 85.222（7）, ρ = 75.439（7）, γ = 78.736（8）°, Z = 2, V= 1057.8（14） A3, D,.= 1.468 mg/m3, p = 0.220 mm-1, F（000） = 476, the final R = 0.0608 and wR = 0.1754 for 3199 observed reflections （1 〉20（/））. Interestingly, compound 1 exhibits good photochromic properties with alternate irradiation of UV light and visible light （〉 510 nm） to form two photoisomers in hexane solution and crystal phase.展开更多
Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic m...Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic moleculehaving low ionization potential, e.g., N,N,N',N'-tetramethyl-p-phenylene diamine doped in poly(methyl methacrylate)(PMMA) film was easily photoionized by intense laser ligh excitation, giving a colored radical cation (photochromism) anda trapped electron in PMMA matrix. As a reversed process, the radical cation recombined with the trapped electron, showingdiscoloration and emitting luminescence, either isothermal luminescence (ITL), or thermoluminescence (TL). In this report,ITL and TL through the charge recombination process were studied and the luminescence was suggested as a mean of the read-out of photorecording.展开更多
A series of inorganic-organic thin films based on uniformly dispersed nanoparticles of polyoxometalates （POM）entrapped in polyacrylamide （PAM） matrix were prepared by ultrasonic method with different irradiation t...A series of inorganic-organic thin films based on uniformly dispersed nanoparticles of polyoxometalates （POM）entrapped in polyacrylamide （PAM） matrix were prepared by ultrasonic method with different irradiation time.The microstructure, photochromic behavior and mechanism of the films were studied by transmission electron microscopy （TEM）, ultraviolet-visible spectra （UV-VIS） and Fourier transform-infrared spectroscopy （FT-IR）.The microstructure and photochromic properties of the hybrid thin films could be controlled by ultrasound.TEM image revealed that the average size of phosphotungstic acid （PWA） nanoparticles decreased from 20 to 10 nm with the ultrasound irradiation time from 30 to 60 min. After irradiated with ultraviolet light,the transparent films changed from colorless to blue and showed reversible photochromism. The hybrid film, with ultrasound irradiation for 60 min had higher photochromic efficiency and faster bleaching reaction than the one with ultrasound irradiation for 30 min. FT-IR spectra showed that the Keggin geometry of heteropolyoxometalate was still preserved inside the composites, and the interactions between polyanions and polymer matrix increased as the ultrasound time prolonged. It is suggested that the mechanism of the different photochromic properties for the inorganic-organic thin films is the variation of the microstructure and interfacial interactions induced by ultrasound.展开更多
A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These vi...A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These viologen copolymers can exchange their anionwith NH_4PF_6 in methanol to improve their solubility in organic solvents such as DMFand acetone. Compared with the corresponding low molecular viologens, these viologencopolymers have relatively lower color development rate under UV light and fade fasterin air due to less affinity to photo-reductant and deficiency of association between theircation radicals. Their photofatigue resistant ability is also slightly better than that of lowmolecular vinlogens.展开更多
The photochromism in CaS:Sm (from white to pink) was observed for the first time by exposing it to ultraviolet light. The experiments results show that the absorption intensity of Sm2+ in the range of 500 similar to 6...The photochromism in CaS:Sm (from white to pink) was observed for the first time by exposing it to ultraviolet light. The experiments results show that the absorption intensity of Sm2+ in the range of 500 similar to 600nm was strongly increased after irradiation. This reveals that there is the valence changing of Sm. If the sample was excited by visible light again, the pink color turned to white, indicating that CaS:Sm has potential application in the field of storage material.展开更多
The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4)...The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4) was determined by single-crystal X-ray diffraction analysis. This crystal belongs to the triclinic system, space group P1 with a = 7.546(3), b = 8.869(3), c = 16.196(5), α = 98.000(4)°, β = 100.803(4)°, γ = 98.449(4)°, Z = 2, V = 1037.6(6) ?~3, Dc = 1.496 mg/m^3, μ = 0.317, F(000) = 474, the final R = 0.0428 and wR = 0.1199 for 4115 observed reflections(I > 2σ(I)). Further study demonstrated this compound underwent reversible photochromism with color-switching between colorlessness and green in crystalline state. Upon 365 nm irradiation, the diarylethene shows one step photochromism to form isomer 1 oc. When irradiated with 312 nm, the stepwise photocyclization reactions occurred in diarylethene dimer through the line of 1 oo to 1 oc to 1 cc.展开更多
The title compound 2,2-dithiophene-naphthopyran （C21H14OS2, Mr = 346.44） was synthesized and characterized by IR,^1lH NMR, elemental analysis and single-crystal X-ray diffraction. It belongs to the monoclinic system...The title compound 2,2-dithiophene-naphthopyran （C21H14OS2, Mr = 346.44） was synthesized and characterized by IR,^1lH NMR, elemental analysis and single-crystal X-ray diffraction. It belongs to the monoclinic system, space group P21/n, with a = 8.2349（14）, b = 6.1964（11）, c = 32.458（5）A, β= 95.051（3）°, V= 1649.8（5）A^3, Z = 4, Dc = 1.395 g/cm^3,μ = 0.327 cm^-1, F（000） = 720, the final R = 0.0559 and wR = 0.1442 for 3370 observed reflections （I 〉 2σ（I））. X-ray analysis revealed that the interatomic distance of C（13）-O（1） is 1.456（3）A, longer than that of normal C-O bond （1.41 - 1.43 A） in a six-membered heterocycle. The UV-vis spectra of the title compound showed that it exhibits excellent photochromic property in polyester coating and solutions.展开更多
The title compound, 2,2-bis（4-tertial butyl phenyl） naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction i...The title compound, 2,2-bis（4-tertial butyl phenyl） naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction in the ring-opened form after hydrolyzation. It belongs to monoclinic, space group P21/c, with a = 14.358（3）, b = 7.6725（15）, c = 24.470（5） А, β= 97.147（4）°, C_33H_36O2, Mr=464.62, V= 2674.8（9）А^3, Z = 4, Dc = 1.154 g/cm^3,μ= 0.070 mm^-1, F（000） = 1000, the final R = 0.0514 and wR = 0.1272 for 5444 observed reflections （I 〉 2σ（I））. X-ray analysis revealed that the C（13）-O（1） bond of the title compound cracks after UV irradiation, the six-membered heterocycles are destroyed, and zwitterionic intermediates come into being. The molecular structure in the ring-opened form is obtained after hydrolyzation. It is infrequent that the single-crystal structure is determined in a ring-opened form. A two-dimensional framework is formed by O-H…O and CAr-H…O hydrogen bonds. The UV-vis spectra show that the title compound exhibits excellent photochromic properties in solutions and polymers.展开更多
The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigate...The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigated by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of D6 in chloroform （CHC13） and tetrahydrofuran （THF） solutions are in accordance with the ftrst order kinetics. The photochromism rate constants of D6 are 101 sI, it is 107 times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties.展开更多
The title compound 2 （C30H27N3O, Mr = 445.55） has been synthesized and its structure was determined by X-ray crystallography method. The crystal is of monoclinic, space group P21/c with a = 17.520（15）, b = 8.640（...The title compound 2 （C30H27N3O, Mr = 445.55） has been synthesized and its structure was determined by X-ray crystallography method. The crystal is of monoclinic, space group P21/c with a = 17.520（15）, b = 8.640（7）, c = 15.439（13） A, β = 98.642（14）°, V = 2310（3） 3, Dc = 1.281 g/cm^3, μ = 0.780 mm^-1, F（000） = 944, Z = 4, the final R = 0.0671 and wR = 0.1790 for 1952 observed reflections with Ⅰ 〉 2σ（Ⅰ）. X-ray analysis revealed that the interatomic distance of C（20）O（1） is 1.464（4） , longer than that of the normal C-O bond （1.41～1.43 A） in the six-membered heterocycle, but this kind of change coincides with other spiro compounds. The six-membered heterocycle containing spiro Csp3-O is nonplanar. The UV-vis spectra of the title compound in polymer films showed that it exhibits excellent photochromic property.展开更多
A new symmetric diarylethene containing cyano group was synthesized and structurally characterized by elemental analysis,IR,1 H NMR and X-ray single-crystal diffraction.It belongs to the monoclinic system,space group ...A new symmetric diarylethene containing cyano group was synthesized and structurally characterized by elemental analysis,IR,1 H NMR and X-ray single-crystal diffraction.It belongs to the monoclinic system,space group C2/c with a = 18.848（6）,b = 8.561（2）,c = 16.875（5） ？,β = 100.398（6）o,V = 1344.6（11） ？~3,Z = 4,μ = 0.262 mm^（-1）,Dc = 1.415 g/cm^3,Mr = 570.56,F（000） = 1160,the final R = 0.0808 and wR = 0.2107 with I 〉 2σ（I）.The two thienyls adopt reactive anti-parallel conformation and the carbon distance of photocyclization is 3.57 ？.The neighboring molecules are stacked closely with C-H…F hydrogen bonding.In addition,the photochromism of the new compound was investigated in solvents with different polarity and PMMA film.The alternative photo-irradiation of 254 nm light and ≥550 visible light can induce the reversible photo-cyclization and photo-reversion with the color interconversion between colorlessness and blue.In THF solution,the λ（max） of diarylethene in PSS in visible band is 585 nm.The diarylethene further reacted with AgBF4 in benzene to give rise to complex 1,which was structurally characterized by elemental analysis,IR,ESI-MS and TG.1 demonstrated reversible photochromism in both solution and PMMA film.The complexation of metal ions with diarylethene leads to a minor red-shift of the λ（max） of 1 in THF in PSS to 590 nm.展开更多
Photochromism is the reversible structural change of the molecules upon light irradiation having different spectral pattern before and after irradiation. Liquid crystal (LC) is a long-range orientational order of the ...Photochromism is the reversible structural change of the molecules upon light irradiation having different spectral pattern before and after irradiation. Liquid crystal (LC) is a long-range orientational order of the molecules in between solid and isotropic liquid phases which share the properties of the crystal and liquid phases. 1-Alkyl-2-(ary-lazo)imidazoles, (Raai-CnH2n+1, R = H, Me and n = 10, 12, 14, 16, 18, 20, 22) exhibits photochromism and two of them (Haai-C18H37 and Haai-C22H45) show Liquid crystal (LC) properties. One of these compounds, Meaai-C16H33 is structurally characterized by single crystal X-ray diffraction study. The compounds upon irradiation with UV light show E-to-Z isomerisation. Quantum yields (φE→Z) of E-to-Z isomerisation vary with the molar mass of the compounds. The reverse transformation, Z-to-E, is recorded in thermal condition. The activation energy (Ea) of isomerisation is determined by the controlled temperature reaction. Liquid crystal property of the molecules is examined by polarizing optical microscopy (POM) and DSC. The carbon chain length n = 18 shows nematic (N)-isotropic (I) phase transition and an unknown Smectic (Sm) phase is observed with n = 22 on heating cycle.展开更多
文摘WO2 and TiO2 colMds were synthesized by the hydrolysis technique and part of the TiO2 colloid was treated by means of the hydrothermal method. The photochromic performances of the resulting materials obtained via combining the WO3 colloid with the treated TiO2 colloid and the non-treated TiO2 colloid, respectively, are very different. The TiO2 colloid without hydrothermal treatment can effectively improve the photochromic performance of the WO3colloid. The TiO2 nanoparticles were investigated in detail by XRD, TEM, surface photovohage spectra（SPS） and field-induced surface photovoltage spectrometry（FISPS）. The photochromism mechanism of WO3 colloid is discussed.
基金supported by the National Natural Science Foundation(Grant No.20372032)Jiangsu Province in China(Grant.No.BK2004085)
文摘The interfacial behaviors of the non-typical amphiphilic compound p-methylphenylazocalix[4]arene 1 and p-chlorophenylazocalix[4]arene 2 at the air/water interface and photochromism in the Langmuir-Blodgett films were studied by surface pressure-area isotherm and UV-Vis spectra. The results indicate that they can form stable monolayers at the air / water interface although they have no hydrophobic alkyl chains, and their LB film underwent reversible trans-cis photoisomerization on UV and daylight illumination.
基金Supported by the NNSFC(21262015,21162011)Science Funds of the Education Office of Jiangxi Province(GJJ11690,GJJ13577)
文摘A new family of photochromic diarylethene compounds, 1-（2-cyano-l,5-dimethyl- 4-pyrryl）-2-[2-methyl-5-（3-pyridyl）-3-thienyl]perfluorocyclopentene （lo） having an unsymmetrical pyrryl and thienyl substituted hexafluorocyclopentene unit, was synthesized and its structure was determined by X-ray analysis. The crystal belongs to triclinic system, space group PI with a = 8.897（7）, b = 10.139（8）, c = 12.361（9） A, α = 85.222（7）, ρ = 75.439（7）, γ = 78.736（8）°, Z = 2, V= 1057.8（14） A3, D,.= 1.468 mg/m3, p = 0.220 mm-1, F（000） = 476, the final R = 0.0608 and wR = 0.1754 for 3199 observed reflections （1 〉20（/））. Interestingly, compound 1 exhibits good photochromic properties with alternate irradiation of UV light and visible light （〉 510 nm） to form two photoisomers in hexane solution and crystal phase.
文摘Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic moleculehaving low ionization potential, e.g., N,N,N',N'-tetramethyl-p-phenylene diamine doped in poly(methyl methacrylate)(PMMA) film was easily photoionized by intense laser ligh excitation, giving a colored radical cation (photochromism) anda trapped electron in PMMA matrix. As a reversed process, the radical cation recombined with the trapped electron, showingdiscoloration and emitting luminescence, either isothermal luminescence (ITL), or thermoluminescence (TL). In this report,ITL and TL through the charge recombination process were studied and the luminescence was suggested as a mean of the read-out of photorecording.
文摘A series of inorganic-organic thin films based on uniformly dispersed nanoparticles of polyoxometalates （POM）entrapped in polyacrylamide （PAM） matrix were prepared by ultrasonic method with different irradiation time.The microstructure, photochromic behavior and mechanism of the films were studied by transmission electron microscopy （TEM）, ultraviolet-visible spectra （UV-VIS） and Fourier transform-infrared spectroscopy （FT-IR）.The microstructure and photochromic properties of the hybrid thin films could be controlled by ultrasound.TEM image revealed that the average size of phosphotungstic acid （PWA） nanoparticles decreased from 20 to 10 nm with the ultrasound irradiation time from 30 to 60 min. After irradiated with ultraviolet light,the transparent films changed from colorless to blue and showed reversible photochromism. The hybrid film, with ultrasound irradiation for 60 min had higher photochromic efficiency and faster bleaching reaction than the one with ultrasound irradiation for 30 min. FT-IR spectra showed that the Keggin geometry of heteropolyoxometalate was still preserved inside the composites, and the interactions between polyanions and polymer matrix increased as the ultrasound time prolonged. It is suggested that the mechanism of the different photochromic properties for the inorganic-organic thin films is the variation of the microstructure and interfacial interactions induced by ultrasound.
基金This work is supported by the National Natural Science Foundation of China.
文摘A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These viologen copolymers can exchange their anionwith NH_4PF_6 in methanol to improve their solubility in organic solvents such as DMFand acetone. Compared with the corresponding low molecular viologens, these viologencopolymers have relatively lower color development rate under UV light and fade fasterin air due to less affinity to photo-reductant and deficiency of association between theircation radicals. Their photofatigue resistant ability is also slightly better than that of lowmolecular vinlogens.
文摘The photochromism in CaS:Sm (from white to pink) was observed for the first time by exposing it to ultraviolet light. The experiments results show that the absorption intensity of Sm2+ in the range of 500 similar to 600nm was strongly increased after irradiation. This reveals that there is the valence changing of Sm. If the sample was excited by visible light again, the pink color turned to white, indicating that CaS:Sm has potential application in the field of storage material.
基金Supported by the National Natural Science Foundation of China(21701065)"5511" Science and Technology Innovation Talent Project of Jiangxi Province(20165BCB18015)+2 种基金the Project of Natural Science Foundation of Jiangxi Province(20171ACB20025,20171BAB203011)the Project of the Science Funds of Jiangxi Education Office(GJJ170659)the Project of Jiangxi Advantage Sci-Tech Innovative Team(20142BCB24012)
文摘The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4) was determined by single-crystal X-ray diffraction analysis. This crystal belongs to the triclinic system, space group P1 with a = 7.546(3), b = 8.869(3), c = 16.196(5), α = 98.000(4)°, β = 100.803(4)°, γ = 98.449(4)°, Z = 2, V = 1037.6(6) ?~3, Dc = 1.496 mg/m^3, μ = 0.317, F(000) = 474, the final R = 0.0428 and wR = 0.1199 for 4115 observed reflections(I > 2σ(I)). Further study demonstrated this compound underwent reversible photochromism with color-switching between colorlessness and green in crystalline state. Upon 365 nm irradiation, the diarylethene shows one step photochromism to form isomer 1 oc. When irradiated with 312 nm, the stepwise photocyclization reactions occurred in diarylethene dimer through the line of 1 oo to 1 oc to 1 cc.
基金The work was supported by the National Natural Science Foundation of China (Nos 20602020 and 20490210)
文摘The title compound 2,2-dithiophene-naphthopyran （C21H14OS2, Mr = 346.44） was synthesized and characterized by IR,^1lH NMR, elemental analysis and single-crystal X-ray diffraction. It belongs to the monoclinic system, space group P21/n, with a = 8.2349（14）, b = 6.1964（11）, c = 32.458（5）A, β= 95.051（3）°, V= 1649.8（5）A^3, Z = 4, Dc = 1.395 g/cm^3,μ = 0.327 cm^-1, F（000） = 720, the final R = 0.0559 and wR = 0.1442 for 3370 observed reflections （I 〉 2σ（I））. X-ray analysis revealed that the interatomic distance of C（13）-O（1） is 1.456（3）A, longer than that of normal C-O bond （1.41 - 1.43 A） in a six-membered heterocycle. The UV-vis spectra of the title compound showed that it exhibits excellent photochromic property in polyester coating and solutions.
基金supported by the National Natural Science Foundation of China (Nos. 20602020 and 20490210)
文摘The title compound, 2,2-bis（4-tertial butyl phenyl） naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction in the ring-opened form after hydrolyzation. It belongs to monoclinic, space group P21/c, with a = 14.358（3）, b = 7.6725（15）, c = 24.470（5） А, β= 97.147（4）°, C_33H_36O2, Mr=464.62, V= 2674.8（9）А^3, Z = 4, Dc = 1.154 g/cm^3,μ= 0.070 mm^-1, F（000） = 1000, the final R = 0.0514 and wR = 0.1272 for 5444 observed reflections （I 〉 2σ（I））. X-ray analysis revealed that the C（13）-O（1） bond of the title compound cracks after UV irradiation, the six-membered heterocycles are destroyed, and zwitterionic intermediates come into being. The molecular structure in the ring-opened form is obtained after hydrolyzation. It is infrequent that the single-crystal structure is determined in a ring-opened form. A two-dimensional framework is formed by O-H…O and CAr-H…O hydrogen bonds. The UV-vis spectra show that the title compound exhibits excellent photochromic properties in solutions and polymers.
基金The authors thank the National Natural Science Foundation of China(No.29874020)for financial support.
文摘The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigated by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of D6 in chloroform （CHC13） and tetrahydrofuran （THF） solutions are in accordance with the ftrst order kinetics. The photochromism rate constants of D6 are 101 sI, it is 107 times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties.
基金The project was supported by the NNSFC (No. 20490210 and 20372039)
文摘The title compound 2 （C30H27N3O, Mr = 445.55） has been synthesized and its structure was determined by X-ray crystallography method. The crystal is of monoclinic, space group P21/c with a = 17.520（15）, b = 8.640（7）, c = 15.439（13） A, β = 98.642（14）°, V = 2310（3） 3, Dc = 1.281 g/cm^3, μ = 0.780 mm^-1, F（000） = 944, Z = 4, the final R = 0.0671 and wR = 0.1790 for 1952 observed reflections with Ⅰ 〉 2σ（Ⅰ）. X-ray analysis revealed that the interatomic distance of C（20）O（1） is 1.464（4） , longer than that of the normal C-O bond （1.41～1.43 A） in the six-membered heterocycle, but this kind of change coincides with other spiro compounds. The six-membered heterocycle containing spiro Csp3-O is nonplanar. The UV-vis spectra of the title compound in polymer films showed that it exhibits excellent photochromic property.
基金supported by the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars(Yu Zhong)Shaanxi Natural Science Foundation(No.2017JM2021)Scientific Research Program of Xi’an University of Technology(No.2015CX001)
文摘A new symmetric diarylethene containing cyano group was synthesized and structurally characterized by elemental analysis,IR,1 H NMR and X-ray single-crystal diffraction.It belongs to the monoclinic system,space group C2/c with a = 18.848（6）,b = 8.561（2）,c = 16.875（5） ？,β = 100.398（6）o,V = 1344.6（11） ？~3,Z = 4,μ = 0.262 mm^（-1）,Dc = 1.415 g/cm^3,Mr = 570.56,F（000） = 1160,the final R = 0.0808 and wR = 0.2107 with I 〉 2σ（I）.The two thienyls adopt reactive anti-parallel conformation and the carbon distance of photocyclization is 3.57 ？.The neighboring molecules are stacked closely with C-H…F hydrogen bonding.In addition,the photochromism of the new compound was investigated in solvents with different polarity and PMMA film.The alternative photo-irradiation of 254 nm light and ≥550 visible light can induce the reversible photo-cyclization and photo-reversion with the color interconversion between colorlessness and blue.In THF solution,the λ（max） of diarylethene in PSS in visible band is 585 nm.The diarylethene further reacted with AgBF4 in benzene to give rise to complex 1,which was structurally characterized by elemental analysis,IR,ESI-MS and TG.1 demonstrated reversible photochromism in both solution and PMMA film.The complexation of metal ions with diarylethene leads to a minor red-shift of the λ（max） of 1 in THF in PSS to 590 nm.
文摘Photochromism is the reversible structural change of the molecules upon light irradiation having different spectral pattern before and after irradiation. Liquid crystal (LC) is a long-range orientational order of the molecules in between solid and isotropic liquid phases which share the properties of the crystal and liquid phases. 1-Alkyl-2-(ary-lazo)imidazoles, (Raai-CnH2n+1, R = H, Me and n = 10, 12, 14, 16, 18, 20, 22) exhibits photochromism and two of them (Haai-C18H37 and Haai-C22H45) show Liquid crystal (LC) properties. One of these compounds, Meaai-C16H33 is structurally characterized by single crystal X-ray diffraction study. The compounds upon irradiation with UV light show E-to-Z isomerisation. Quantum yields (φE→Z) of E-to-Z isomerisation vary with the molar mass of the compounds. The reverse transformation, Z-to-E, is recorded in thermal condition. The activation energy (Ea) of isomerisation is determined by the controlled temperature reaction. Liquid crystal property of the molecules is examined by polarizing optical microscopy (POM) and DSC. The carbon chain length n = 18 shows nematic (N)-isotropic (I) phase transition and an unknown Smectic (Sm) phase is observed with n = 22 on heating cycle.
