螺烯类化合物的二阶非线性光学性质研究

Nonlinear optical (NLO) materials have broad application prospects, such as in photoelectric conversion, optical switch, and optical information processing etc. Thus, probing and finding excellent NLO materials are the pursuing objectives of researchers. Chiral compounds are ideal structures to investigate second-order NLO effects due to their intrinsic noncentrosymmetry, which allows NLO response to be observed even in highly symmetric media. Helicene and its derivatives exhibit great application prospect in photoelectric material field due to their good thermostability, conjugation, and structural modification. The main purpose is to investigate their NLO origin, solve the contribution between intramolecular and intermolercular charger transfer to NLO response that cannot be determined by experiment, analyze charge transfer between ground state and excited state by different combinations of electron donors and acceptors, find the key functional unit to enhance NLO response, design new materials with excellent NLO response and high transparency, and provide theoretical guidance for experimental synthesis. Moreover, we systemically investigate their chiroptical properties, discuss the style of exciton couplet, establish the relationship between the structure and circular dichroism spectra, and provide the theoretical basis for determining their absolute configurations.

非线性光学（NLO）材料在光电转换、光开关、光信息处理领域有着广泛应用前景，因此探索和发现性能优越的NLO材料一直是科学工作者追求的目标。手性化合物不仅具有有机化合物NLO材料的优点，而且内在的非中心对称结构不需要生色团的偶极有序排列就可以显示出二阶NLO响应。螺烯类化合物具有好的热稳定、共轭性和易于结构修饰等优点，在光电材料领域展现出广阔的应用前景。本项目以螺烯及其衍生物为研究对象，从理论上研究NLO性质起源,解决实验上难以确定的分子内和分子间各自电荷转移对NLO响应贡献的难题。在此基础上,通过不同给体或受体组合的基态和激发态电荷转移特性分析，探讨有利于电荷转移的组合方式，设计和筛选出具有NLO响应系数大和‘透明性’好的新型NLO材料，为定向实验合成提供指导。同时研究螺烯类化合物手性光学性质，讨论激子耦合方式，建立结构和圆二色性间的关系，为确定其绝对构型提供理论依据。

非线性光学（NLO）材料在光电转换、光开关、光信息处理领域有着广泛应用前景，因此探索和发现性能优越的NLO材料一直是科学工作者追求的目标。手性化合物不仅具有有机化合物NLO材料的优点，而且内在的非中心对称结构不需要生色团的偶极有序排列就可以显示出二阶NLO响应。螺旋烯类化合物是具有螺旋手性的邻位稠合多环芳族或杂芳族化合物，其手性源自非平面螺旋状骨架。它们固有的不对称骨架和有趣的物理化学性质使得它们在催化，分子机，染料，液体晶体技术，非线性光学，分子识别和有机电子具有广泛的应用。本项目以螺烯及其衍生物为研究对象，从理论上研究了NLO性质起源, 确定了分子内和分子间各自电荷转移对NLO响应的贡献；通过不同给体或受体组合的基态和激发态电荷转移特性分析，发现了有利于电荷转移的组合方式，设计出具有NLO响应系数大和‘透明性’好的新型NLO材料；研究了螺烯类化合物手性光学性质，讨论激子耦合方式，建立起结构和圆二色性间的关系，为确定绝对构型提供了理论依据。本项目研究成果对非线性光学材料的实验设计与合成具有重要指导意义。