Bifunctional pyrazoline derivatives 5 and 6 containing azobenzene group were prepared. The difference between them was the length of the flexible chain connecting the two chromophores. Compound 6 had four more methyle...Bifunctional pyrazoline derivatives 5 and 6 containing azobenzene group were prepared. The difference between them was the length of the flexible chain connecting the two chromophores. Compound 6 had four more methylenes than compound 5. UV\|Vis spectra of compounds 5 and 6 were the simple superposition of the absorbance of the azobenzene and pyrazoling and showed that pyrazoline had no effect on the isomerization of azobenzene. When there were two methylenes between azobenzene and pyrazoline, the fluorescent intensity of compound 5 decreased greatly compared with that of compound 6. It means that the intramolecular Electronic Energy Transfer has taken place in compound 5. In compound 6, this process could not occur because of the longer flexible chain between the two chromophores.展开更多
Three azo-dyes, 4′-{[(2-hydroxylethyl)methyl]amino}-4-nitroazobenzene(1), 1-[4-(4′-nitrophenyl)-azophenyl]-3,5-biphenyl-2-pyrazoline(2) and 1-[4-(4′-nitrophenyl)-azophenyl]-5-(4′-hydroxylphenyl)-3-phenyl-2-pyrazol...Three azo-dyes, 4′-{[(2-hydroxylethyl)methyl]amino}-4-nitroazobenzene(1), 1-[4-(4′-nitrophenyl)-azophenyl]-3,5-biphenyl-2-pyrazoline(2) and 1-[4-(4′-nitrophenyl)-azophenyl]-5-(4′-hydroxylphenyl)-3-phenyl-2-pyrazoline(3) were synthesized. The polarized photoinduced birefringence and relaxation process of those azo-dyes doped with PMMA films were investigated under polarized laser intensity. The results indicate that compounds with pyrazoline group have a high storage rate and thermal stability. It has been found that the birefringence signals decrease with the increase of the temperature, but the effect of temperature is different for the three compounds. Compounds 2 and 3, with pyrazoline groups have a good thermal stability at room temperature, and compound 3 can even keep 30% of its maximum birefringence at 90 ℃.展开更多
Azobenzene-modified pullulan with different substitution degrees were prepared by changing feed molar ratio of 4-phenylazophenyloxybutyrate acid to pullulan. The structure of the modified pullulan were characterized b...Azobenzene-modified pullulan with different substitution degrees were prepared by changing feed molar ratio of 4-phenylazophenyloxybutyrate acid to pullulan. The structure of the modified pullulan were characterized by 1 H NMR and FTIR spectroscopies. The substitution degrees were determined by elemental analysis and UV-Vis spectra. Photochromism property in solution was investigated by UV-Vis spectroscopy, isomerization behavior of azobenzene moeties of polymer under irradiation at 350 nm is obvious. After 4 min irradiation, trans isomer of sample 3 change into cis isomer completely. Furthermore, unlike pullulan, which is soluble only in H2O or DMSO, the solubility of these products in common organic solvent increased greatly.展开更多
文摘Bifunctional pyrazoline derivatives 5 and 6 containing azobenzene group were prepared. The difference between them was the length of the flexible chain connecting the two chromophores. Compound 6 had four more methylenes than compound 5. UV\|Vis spectra of compounds 5 and 6 were the simple superposition of the absorbance of the azobenzene and pyrazoling and showed that pyrazoline had no effect on the isomerization of azobenzene. When there were two methylenes between azobenzene and pyrazoline, the fluorescent intensity of compound 5 decreased greatly compared with that of compound 6. It means that the intramolecular Electronic Energy Transfer has taken place in compound 5. In compound 6, this process could not occur because of the longer flexible chain between the two chromophores.
文摘Three azo-dyes, 4′-{[(2-hydroxylethyl)methyl]amino}-4-nitroazobenzene(1), 1-[4-(4′-nitrophenyl)-azophenyl]-3,5-biphenyl-2-pyrazoline(2) and 1-[4-(4′-nitrophenyl)-azophenyl]-5-(4′-hydroxylphenyl)-3-phenyl-2-pyrazoline(3) were synthesized. The polarized photoinduced birefringence and relaxation process of those azo-dyes doped with PMMA films were investigated under polarized laser intensity. The results indicate that compounds with pyrazoline group have a high storage rate and thermal stability. It has been found that the birefringence signals decrease with the increase of the temperature, but the effect of temperature is different for the three compounds. Compounds 2 and 3, with pyrazoline groups have a good thermal stability at room temperature, and compound 3 can even keep 30% of its maximum birefringence at 90 ℃.
文摘Azobenzene-modified pullulan with different substitution degrees were prepared by changing feed molar ratio of 4-phenylazophenyloxybutyrate acid to pullulan. The structure of the modified pullulan were characterized by 1 H NMR and FTIR spectroscopies. The substitution degrees were determined by elemental analysis and UV-Vis spectra. Photochromism property in solution was investigated by UV-Vis spectroscopy, isomerization behavior of azobenzene moeties of polymer under irradiation at 350 nm is obvious. After 4 min irradiation, trans isomer of sample 3 change into cis isomer completely. Furthermore, unlike pullulan, which is soluble only in H2O or DMSO, the solubility of these products in common organic solvent increased greatly.
