CAJ | 학술논문

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.
채용밀도범함이론재 B3LYP/6-31+G(d)수평상연구료4충금속 Mg, Ni, Cu, Zn 배위적자유계람(FBP)급담혼잡계람(NECP)적궤하결구급분자궤도능급.채용함시밀도범함이론(TD-DFT)방법계산료금속여2충계람배위후재기체조건하적전자흡수광보,포괄격발능、흡수파장、약천조성화진자강도.계산결과표명,여금속배위적 FBP(M-FBP)구유 D4h대칭성,분자궤도능급 HOMO/ HOMO-1화 LUMO/ LUMO+1인능급상근발생간병, HOMO-LUMO 궤도능급차대약3.0 eV,재 Soret 대출현교강흡수봉.유우 C/ N 원자위치적개변,비대칭성결구적 M-NECP 전선궤도조성발생개변,궤도능급차(HOMO-LUMO)감소지2.6 eV 좌우,차능급발생분렬, Soret 대출현다개전자흡수보봉, Q 대야출현흡수봉.본문연구료수、록방화분3충불동겁성용제대 M-FBP 화 M-NECP 적분자궤도급전자흡수광보적영향,결과표명,수용제겁성감약금속배합물적전자흡수광보발생홍이,병차흡수봉강도증강.
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.