中文摘要：

采用密度泛函理论在 B3LYP/6-31＋G（d）水平上研究了4种金属 Mg, Ni, Cu, Zn 配位的自由卟啉（FBP）及氮混杂卟啉（NECP）的几何结构及分子轨道能级.采用含时密度泛函理论（TD-DFT）方法计算了金属与2种卟啉配位后在气体条件下的电子吸收光谱,包括激发能、吸收波长、跃迁组成和振子强度.计算结果表明,与金属配位的 FBP（M-FBP）具有 D4h对称性,分子轨道能级 HOMO/ HOMO-1和 LUMO/ LUMO＋1因能级相近发生简并, HOMO-LUMO 轨道能级差大约3.0 eV,在 Soret 带出现较强吸收峰.由于 C/ N 原子位置的改变,非对称性结构的 M-NECP 前线轨道组成发生改变,轨道能级差（HOMO-LUMO）减小至2.6 eV 左右,且能级发生分裂, Soret 带出现多个电子吸收谱峰, Q 带也出现吸收峰.本文研究了水、氯仿和苯3种不同极性溶剂对 M-FBP 和 M-NECP 的分子轨道及电子吸收光谱的影响,结果表明,随溶剂极性减弱金属配合物的电子吸收光谱发生红移,并且吸收峰强度增强.

英文摘要：

On the basis of detailed density functional theory（DFT）, the molecular geometrical structures and orbital energy levels of free base porphyrin（FBP） and neo-confused porphyrin（NECP） coordinated with Mg, Ni, Cu, Zn were studied at B3LYP/ 6-31＋G（d） level. The electronic absorption spectra of metal coordinated porphyrins were studied in gas phase at time dependent density functional level, including the excitation ener-gy, absorption wavelength, oscillator strength and the orbital composition of the electronic transition. Since the metal coordinated FBPs（ M-FBP） have D4h symmetry, HOMO/ HOMO-1, LUMO/ LUMO＋1 degenerate re-spectively with the similar orbital energy level. The energy gaps of HOMO-LUMO of M-FBPs are about 3. 0 eV. The structure and orbital properties of M-FBPs evolve strong Soret bands in the absorption spectra. Due to the change of C / N atom in the center structure of NECP, M-NECP molecular frontier orbitals composition is more complicated than that of M-FBP. In M-NECPs, the molecular orbital energy gaps（HOMO-LUMO） re-duce to about 2. 6 eV. The C / N exchange strategy can vary the molecular symmetry and molecular orbital composition of M-NECPs, which leads to the energy level splitting, strong electronic absorption peaks of Soret band and the appearance of Q absorption band. All the parameters of M-FBPs and M-NECPs were investigated in three different solvents（water, chloroform and benzene）. Under the solvent conditions, the electronic ab-sorption spectra of M-FBP and M-NECP take place red shift along with the weaken polarity of solvent（water, chloroform, benzene） and enhance the absorption peak intensity.