含咔唑生色团的有机芳香杂环分子的二阶非线性光学性质

采用密度泛函理论B3LYP/6-31G^*方法, 对一系列含咔唑生色团的有机芳香杂环分子进行结构优化, 并采用有限场(FF)和含时密度泛函理论(TD-DFT)方法在6-311G^**水平上探讨了体系的二阶非线性光学(NLO)性质和电子光谱. 结果表明, 咔唑取代基推或拉电子能力的改变和引入芳香杂环对研究分子的极化率α和二阶NLO系数β值都有较大影响. 当取代基分别连有拉电子硝基和推电子羟基, 以及引入呋喃杂环都可以使体系分子的β值随分子的最大吸收波长λ_max的增大而减小(蓝移). 该系列化合物兼具有很大的二阶非线性响应与良好的透光范围, 避免了“非线性-透光性”矛盾, 可能在非线性材料领域中有很大的潜在应用价值.

Second-Order Nonlinear Optical Properties of Organic Heteroaromatic Molecules with Carbazole Chromophores

Density functional theory (DFT) B3LYP/6-31G method was used to optimize the geometrical structures of a series of heteroaromatic molecules with carbazole chromophores.The second-order nonlinear optical (NLO) properties and electronic spectra were then studied by finite field (FF) and time-dependent DFT (TD-DFT) methods at the 6-311G level.The results showed that the polarizability α and the second-order NLO coefficient β values of all molecules were influenced greatly by the change of the push-pull electronic ability of the carbazole substituent groups and the introduction of heteroaromatic.When the pull electronic nitro and the push electronic hydroxyl were linked by carbazole substituent groups respectively and the furan heterocycle was introduced,the β values decreased (blue-shifted) with an increase in the maximum absorption wavelengths λmax of the molecules.The "nonlinear-transparency tradeoff" conflict was avoided because of the high second-order NLO responses and good transparency.All the compounds may have potential application in the development of NLO materials.