中文摘要：

以实验合成出的Schiff碱配体和Co（Ⅱ）配合物为母体，设计了Schiff碱配体和具有三维结构的Co（Ⅱ）配合物．采用密度泛函理论的B3LYP／6-31g（d）-FF方法对具有开壳层电子组态Co（Ⅱ）配合物及相应配体的二阶非线性光学（NLO）效应进行了计算．结果表明：Schiff碱配体形成配合物后分子的二阶NLO性质没有发生大的改变，这是由于金属Co^2＋离子在配合物电荷转移（CT）过程中起到了桥的作用，对分子的二阶NLO响应直接贡献不大．结合配合物的前线分子轨道分析发现，在分子内电荷转移过程中，对分子二阶NLO系数的主要贡献是配体内电荷转移（ILCT）跃迁．

英文摘要：

For designing three-dimensional cobalt （Ⅱ） metal complexes and Schiff base ligands, the geometry was taken from the starting structures based on the crystallographic data. The density functional theory （DFT） B3LYP/6-31g（d）-FF method was used to calculate the second-order nonlinear optical （NLO） properties of open-shell cobalt（Ⅱ） metal complexes. The key finding revealed that when compared with the Schiff base ligands, the second-order NLO properties of the metal complexes do not change obviously, the reason being, that the NLO responses of cobalt（Ⅱ） metal complexes are strongly related to intraligand charge transfer transitions. According to the frontier molecular orbitals, the less contribution of Co^2＋ in determining the NLO responses of metal complexes arise from the action of the bridging moiety in the charge transfer processes.