卟啉类化合物是一类重要的光化学材料,其衍生物特殊的光电特性在各个领域中得到了广泛的应用。利用密度泛函理论(DFT)研究了(free base porphyrin,FBP)及其异构体(neo-confused porphyrin,NECP)和(n-confused porphyrin,NCP)三种卟啉环...卟啉类化合物是一类重要的光化学材料,其衍生物特殊的光电特性在各个领域中得到了广泛的应用。利用密度泛函理论(DFT)研究了(free base porphyrin,FBP)及其异构体(neo-confused porphyrin,NECP)和(n-confused porphyrin,NCP)三种卟啉环的几何结构和分子轨道能级。采用TDDFT方法计算真空和溶剂场极化连续模型下三者的吸收光谱。计算表明由于N原子位置变化,FBP,NECP和NCP在Soret带和Q带两个特征吸收峰也有不同。按FBP,NECP和NCP顺序,分子轨道能级LUMO依次降低,HOMO轨道依次升高,从而造成吸收光谱红移。HOMO和HOMO-1轨道能级的分裂造成了FBP和NECP的Soret带的多个吸收峰,而NCP的LUMO和LUMO+1的能级差与其HOMO和HOMO-1能级差几乎相等造成Soret带只有一个最高吸收峰。计算结果表明不同溶剂(苯、氯仿、乙腈和水)条件下三者的Soret带和Q带特征吸收峰均有显著变化。为此重点讨论了N原子位置的变化及在不同性质溶剂下FBP,NCP和NECP三类化合物Soret带/Q带吸收光谱性质的变化规律和机理。展开更多
The photophysical properties of ortho-Cl, meta-Cl and para-Cl substituted tetraphenylporphy-rin-histidine and their zinc (Ⅱ) complexes have been studied by means of steady-state absorption and fluo-rescence spectrosc...The photophysical properties of ortho-Cl, meta-Cl and para-Cl substituted tetraphenylporphy-rin-histidine and their zinc (Ⅱ) complexes have been studied by means of steady-state absorption and fluo-rescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. For the cases of both free-base and zinc complexes, it was found that the or-tho-chlorine substitution onto the phenyl rings signifi-cantly altered the fluorescence quantum yield, the fluorescence lifetime and the ratio between radiative and nonradiative deactivation rates of the porphyrin chromophore, i.e. the photophysical parameters werequite different from those of meta- and para-substi-tuted compounds. On the other hand, however, theintroduction of covalently-linked histidine did not ex-ert much effects on the photophysical behavior of the porphyrin chromophore. The results are interpreted in terms of the steric effect and the heavy-atom effect from the chlorine atoms substituted onto the phenylrings.展开更多
文摘卟啉类化合物是一类重要的光化学材料,其衍生物特殊的光电特性在各个领域中得到了广泛的应用。利用密度泛函理论(DFT)研究了(free base porphyrin,FBP)及其异构体(neo-confused porphyrin,NECP)和(n-confused porphyrin,NCP)三种卟啉环的几何结构和分子轨道能级。采用TDDFT方法计算真空和溶剂场极化连续模型下三者的吸收光谱。计算表明由于N原子位置变化,FBP,NECP和NCP在Soret带和Q带两个特征吸收峰也有不同。按FBP,NECP和NCP顺序,分子轨道能级LUMO依次降低,HOMO轨道依次升高,从而造成吸收光谱红移。HOMO和HOMO-1轨道能级的分裂造成了FBP和NECP的Soret带的多个吸收峰,而NCP的LUMO和LUMO+1的能级差与其HOMO和HOMO-1能级差几乎相等造成Soret带只有一个最高吸收峰。计算结果表明不同溶剂(苯、氯仿、乙腈和水)条件下三者的Soret带和Q带特征吸收峰均有显著变化。为此重点讨论了N原子位置的变化及在不同性质溶剂下FBP,NCP和NECP三类化合物Soret带/Q带吸收光谱性质的变化规律和机理。
基金supported by the Nationa1 Natural Science Foundation of China(Grant Nos.20072041 and 20133020)the State Kcy Basis Research and Development Plans(Grant No.G1998010100).
文摘The photophysical properties of ortho-Cl, meta-Cl and para-Cl substituted tetraphenylporphy-rin-histidine and their zinc (Ⅱ) complexes have been studied by means of steady-state absorption and fluo-rescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. For the cases of both free-base and zinc complexes, it was found that the or-tho-chlorine substitution onto the phenyl rings signifi-cantly altered the fluorescence quantum yield, the fluorescence lifetime and the ratio between radiative and nonradiative deactivation rates of the porphyrin chromophore, i.e. the photophysical parameters werequite different from those of meta- and para-substi-tuted compounds. On the other hand, however, theintroduction of covalently-linked histidine did not ex-ert much effects on the photophysical behavior of the porphyrin chromophore. The results are interpreted in terms of the steric effect and the heavy-atom effect from the chlorine atoms substituted onto the phenylrings.
