D-A共轭π电子化合物非线性光学性质的分子设计研究

Calculation of hyperpolarizabilities of some π electron donor acceptor molecules

研究了Ｄ－Ａ共轭π电子化合物的分子结构、非线性极化率以及与结构的关系等，解释了这类体系具有较大非线性光学系数的微观机制．结果表明，共轭π电子化合物的结构、跃迁能以及基态与激发态的电荷转移均对非线性光学系数有较大影响．通过在共轭体系两端连接强拉电子集团可以设计出具有很大二阶及三阶非线性极化率的化合物．

The work deals with the investigation of the nonlinearities and structure property relationship of some donor acceptor molecules on the basis of AM1 finite field approach.There is a good consistency between measured and calculated hyperpolarizabilities.Results reveal that conformation,the total amount of charge transfer from donor to acceptor and the vertical transition energy can affect the nonlinearities.Some molecules with large molecular hyperpolarizabilities can be designed through the optimisation for the more extended π electron systems with effective donor and acceptor groups.