有机及金属有机苯乙炔树状分子体系的非线性光学性质的理论研究  

Theoretical Investigations of Nonlinear Optical Properties of the Organic and Organometallic Phenylacetylene Dendrimers

作　　者：刘彩萍[1] 刘萍[1] 吴克琛[1] 

机构地区：[1]中国科学院福建物质结构研究所结构化学国家重点实验室

出　　处：《化学学报》2008年第7期729-737,共9页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.20173064,20573114和90203017);国家科技部(No.2004CB720605)资助项目

摘　　要：应用密度泛函理论研究了一系列有机及金属有机苯乙炔树状分子的激发态性质和非线性光学性质.计算的电子吸收光谱显示这些树状分子均在低能区域有一个最强的吸收;此外,金属有机体系的吸收光谱和有机体系相比发生了明显的红移.非线性光学性质的计算结果表明共轭体系的扩展和金属有机基团的引入都使得苯乙炔树状分子的非线性光学极化率显著增加,尤其是含Ru体系,其β和γ值呈数量级增长.对于有机体系和含Pd体系,发生在共轭体系内部的π→π*电荷跃迁是产生分子一阶和二阶超极化率的主要原因.而含Ru体系相当大的非线性响应则主要起源于Ru的d轨道到共轭体系的π*的跃迁,同时与Ru相邻的C≡C到共轭体系的π→π*跃迁起着辅助贡献.Excited-state properties and the static nonlinear optical （NLO） susceptibilities of a series of organic and organometallic phenylacetylene dendrimers have been studied using the density functional theory （DFT）. The calculated electronic absorption spectra of these phenylacetylene dendrimers exhibit the most intensive excitations in the low-lying region. Besides, the absorption spectra of the organometallic systems show a considerable redshift as compared with the organic analogues. The results of the NLO properties reveal that both the expansion of the organic conjugated structure and the introduction of organometallic groups can lead to the drastic increase of the molecular first and second hyperpolarizabilities, especially for the dendrimers including ruthenium, whose β and γ values are enlarged by about 1-2 orders of magnitude. For the organic dendrimers and the organometallic ones involving palladium, the charge transfers with π→π character occurring with the conjugated configurations are predominant for the molecular first and second hyperpolarizabilities. And on the other hand, the extremely high hyperpolarizabilities of the organometallic systems including ruthenium originate mainly from the transitions from ruthenium d-orbitals to π orbitals located at the conjugated structures. In addition, the charge transfers of π→π from the C≡C adjacent to ruthenium to the conjugated structures make minor contributions to their β and γ values.

关 键 词：密度泛函理论 有机苯乙炔树状分子 金属有机苯乙炔树状分子 激发态性质 非线性光学性质 

分 类 号：O621.2[理学—有机化学]