某些过渡金属钌配合物非线性光学性能的从头算和密度泛函理论研究

实验发现金属钌的某些配合物具有大的非线性光学性能。我们的理论研究表明 金属钌配合物Ru(NH_3)_4L~DL~A]~(n+) (n = 2，3；L~D，L~A =吡啶衍生物配体) 的非线性光学性能取决于推电子基团L~D的给电子能力以及拉电子基团L~A的受电子 能力，L~D和L~A的推拉电子越强越有利于提高配合物的二阶非线性光学系数β，因 此带正电荷的L~A能大幅度提高β值。虽然增加共轭体系的长度有利于提高β值， 但在Ru的配合中，吡啶环间或吡淀环与苯环间不一定要保持共面也会有大的β值。 DFT和ab initio方法的计算结果对比表明，对于含过渡金属Ru的化合物，在HF水平 上难以得到满意的结论，由从头算有限场方法计算得到的β值偏小，而用TDDFT方 法能得到可与实验值符合较好的结果。

TDDFT and ab initio Study on the Quadratic Hyperpolarizabilities of trans-Tetraammineruthenium(II) Complexes

A series of large molecular quadratic hyperpolarizabilities in donor/acceptor substituted trans-tetraammineruthenium(II) complexes Ru(NH_3)_4L~DL~A]~(n+) (n = 2, L~D = 4-(dimethylamino)pyridine, L~A = 4-pyridinecarboxaldehyde (1), 4-acetylpyridine (2), ethyl isonicotinate (3), or n = 3, L~A = N-methyl-4,4'-bipyridinium (4), N- (4-acetylphenyl)-4,4'-bipyridinium (4-AcPhQ~+) (5), and n = 3, L~D = NH_3, L~A = (4-AcPhQ~+) (6) has been studied by using the TDDFT and ab initio HF method. It is found that the magnitude of the static hyperpolarizabilities β_0 increases as the donor/accepter strength of L~D/L~A increases. The co-planes of pyridine or benzene ring are not necessary to maintain the large nonlinear optic properties. According to our study on Ru complexes, TDDFT method is more reliable than HF method in β-calculation.