酞菁基态和激发态的计算

采用DFT方法在B3LYP/6-31G水平上得到了H2Pc(酞菁)的优化结构,并在此基础上采用TDDFT方法计算了激发态.通过与H2P(卟吩)、H2Pz(四氮卟吩)和H2TBP(四苯并卟啉)的比较,研究了苯并取代以及氮杂取代对H2Pc的分子轨道和激发态的影响,上述取代效应使得H2Pc的HOMO-1(132 b1u)和HOMO-3(130 b1u)轨道发生了翻转,氮杂取代的影响尤其明显.这两种取代都使得Q带振子强度增大,在这四种化合物中,H2Pc的振子强度最大.TDDFT计算结果与实验值符合得较好.

Calculation of Ground and Excited States of Free Base Phthalocyanine

The structure of free base phthalocyanine (H2Pc) has been predicted using density functional theory (DFT) at the B3LYP/6-31G level and time-dependent density functional theory (TDDFT) has been applied to the excited states of H2Pc.The effects of tetraaza substitutions and tetrabenzo annulations on the molecular orbitals and excited states of H2Pc were examined by the comparison with H2P, H2Pz and H2TBP.These substitutions lead to the inversion of HOMO-1 (132 b1u) and HOMO-3 (130 b1u) and as a result the spectra of H2Pc could not be interpreted by using the Gouterman four-orbital model. The effects of tetraaza subsitution are especially obvious which cause not only the B band but also the Q bands of H2Pz and H2Pc unable to be interpreted by using the Gouterman four-orbital model. Both the tetraaza substitutions and tetrabenzo annulations cause the oscillator strengths of Q band stronger, so the oscillator strengths of H2Pc are the largest among these compounds. The TDDFT energies are in good agreement with the experimental spectra.