噻唑衍生物电子光谱和二阶非线性光学性质的理论研究

Theoretical Studies on Electronic Structures and Second-order Polarizabilities of Thiazole Derivatives

采用量子化学密度泛函方法(DFT)在B3LYP/6-31G(d)水平上对有机二阶非线性光学生色团(E)-2-(5-(4-(双(4-甲氧苯基)氨基)苯乙烯基)噻唑-5)三氰乙烯(TPA-Ti2-TCV)(1)和(E)-2-(5-(4-(双(4-甲氧苯基)氨基)苯乙烯基)噻唑-2)三氰乙烯(TPA-Ti5-TCV)(2)进行几何构型的完全优化,在优化所得构型的基础上,采用含时密度泛函方法(TDDFT)在6-31G(d)基组水平上计算了电子吸收光谱的跃迁性质.再采用有限场法(FF)在B3LYP/6-31G(d)水平上计算了分子的一阶超极化率β.计算结果表明,三芳胺在噻唑环上取代C5比取代C2有更大的一阶超极化率,这是由于噻唑的区域化学性导致ΔEHOMO-LUMO(TPA-Ti2-TCV)比ΔEHOMO-LUMO(TPA-Ti5-TCV)大很多造成的.

Two thiazole-based chromophores were fully optimized with density function theory at B3LYP/6-31G（d） level.Their calculated results are in accordance with the related experiments very well.The parameters which resulted in the difference of the two chromopheres were also calculated with TD-DFT method at the same calculation level.The result indicated that the chromophore（E）-2-（5-（4-（bis（4-methoxyphenyl）amino）styryl）thiazol-2-yl）ethene-1,1,2-tricarbonitrile（TPA-Ti5-TCV） had a larger hyperpolarizability,which was mainly due to its lower ground state to first excited state bandgap caused by the regiochemistry of thiazole.