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在6-31G(d,p)水平上用B3LYP(DFT)方法对联萘桥联推拉双卟啉Ⅱ_c系列分子进行几何构型优化。用ZINDO/SOS方法计算了这些分子的一阶超极化率。计算结果表明:采用具有较大一阶超极化率的卟啉单体构建的手性双卟啉分子,其一阶超极化率有显著提高。此外,推拉基团的排列方式不同会导致基态偶极矩以及一阶超极化率存在明显差别。一阶超极化率随着基态偶极距μ_0增大而增强。双卟啉系列分子一阶超极化率提高主要起源于激子跃迁态偶极耦合作用的增强。跃迁通道分析表明:偶极耦合增强不仅与B带激子跃迁态有关,还与CT态密切相关。
The B3LYP (DFT) method was used to optimize the geometrical configuration of binaphthyl bridged push-pull porphyrin Ⅱ-c series at 6-31G (d, p) level. The first order hyperpolarizabilities of these molecules were calculated using the ZINDO / SOS method. The calculated results show that the first-order hyperpolarizabilities of chiral porphyrin molecules constructed by porphyrins with larger first-order hyperpolarizabilities are significantly increased. In addition, the different arrangement of the push-pull groups leads to the obvious difference of ground-state dipole moment and first-order hyperpolarizability. The first-order hyperpolarizability increases as the ground-state dipole moment μ_0 increases. The first-order hyperpolarizability of the bis-porphyrin series molecules mainly originated from the enhancement of the dipolar coupling in the excitonic transition state. The transition channel analysis shows that the enhancement of dipole coupling is not only related to the B-band excitonic transition state, but also to the CT state.