Though the photo-physical properties of free base porphyrin are attractive, there are still problems for the materials with weak and narrow range absorption of visible light. The unsymmetrical neo-confused porphyrin d...Though the photo-physical properties of free base porphyrin are attractive, there are still problems for the materials with weak and narrow range absorption of visible light. The unsymmetrical neo-confused porphyrin derivatives were introduced as novel materials for the improvement of photo-chemical and photo-physical properties. The density function theory（DFT）and time dependent density function theory（TDDFT） were applied to calculate the absorption spectrum of unsymmetrical neo-confused porphyrin（N-CP） and metal-coordinated N-CP in various solutions. The Ni and Zn coordinated neo-confused porphyrin dipole moment values are smaller than the values of prototype porphyrin（Pro P） and N–CP. According to the electrophilicity index ω, Ni coordinated N–CP（Ni–N–CP） is susceptible to the polarity of solvents, while the Zn coordinated derivative（Zn–N–CP） is more immune to the solvent environment. Unlike the Gouterman＇s four frontier orbital model of common porphyrin materials, the electron transitions of N–CPs and metalcoordinated N–CPs from H–2 or lower molecular orbitals also contribute to ultraviolet and visible absorption. Most of oscillator strength f values of Zn–N–CP are significantly higher than the values of Ni–N–CP, which reflects the higher absorption intensity of Q and Soret bands. The maximum wavelength at 702.2 nm in vacuum drew our attention to the novel material. The broad absorption range, intense red-shifted Q band and higher stability in solvents suggest that N–CPs, especially Zn–N–CP, can be one class of new candidate dye-sensitized materials.展开更多
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
基金supported by the National Natural Science Foundation of China(Nos.21601025,21677029,21571025)Dalian Young Science and Technology Star Project(2017RQ156)
文摘Though the photo-physical properties of free base porphyrin are attractive, there are still problems for the materials with weak and narrow range absorption of visible light. The unsymmetrical neo-confused porphyrin derivatives were introduced as novel materials for the improvement of photo-chemical and photo-physical properties. The density function theory（DFT）and time dependent density function theory（TDDFT） were applied to calculate the absorption spectrum of unsymmetrical neo-confused porphyrin（N-CP） and metal-coordinated N-CP in various solutions. The Ni and Zn coordinated neo-confused porphyrin dipole moment values are smaller than the values of prototype porphyrin（Pro P） and N–CP. According to the electrophilicity index ω, Ni coordinated N–CP（Ni–N–CP） is susceptible to the polarity of solvents, while the Zn coordinated derivative（Zn–N–CP） is more immune to the solvent environment. Unlike the Gouterman＇s four frontier orbital model of common porphyrin materials, the electron transitions of N–CPs and metalcoordinated N–CPs from H–2 or lower molecular orbitals also contribute to ultraviolet and visible absorption. Most of oscillator strength f values of Zn–N–CP are significantly higher than the values of Ni–N–CP, which reflects the higher absorption intensity of Q and Soret bands. The maximum wavelength at 702.2 nm in vacuum drew our attention to the novel material. The broad absorption range, intense red-shifted Q band and higher stability in solvents suggest that N–CPs, especially Zn–N–CP, can be one class of new candidate dye-sensitized materials.
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。
