手性配合物手征光学性质的理论分析和应用研究

Chiral complexes or chelates have been receiving much attention due to their wide range of applications in the domain of asymmetric catalysis, nonlinear optics and chiral separation. However, knowledge about the relationship of their chiroptical properties and chiral structure arrays are poor currently, which has brought some restrictions to the development of relevant disciplines, particularly to the insight of chirality phenomenon as well as the efforts in chiral control. Our recent work reveals that there is a sum-relationship between the chiroptical property of a molecule and the contributions of chiral arrays in the structure. This project intends to continue the theoretical research on this issue in-depth, and pay special attentions on some recently synthesized Ruthenabenzene complexes whose coordination octahedral core exhibits a spontaneous inversion phenomenon. We expect to get a deep insight on the mechanism of spontaneous reversion of the compond by thermodynamics and kinetics calculations, and also to test the possibility of applying the mechanism in the spontaneous resolution of similar complexes. At the same time, we also intend to improve the theoretical models and parameterization scheme used in exciton-chirality methods, and develop a computer program to facilitate the analysis of the circular dichroism spectra of macromolecules. Clearly, this project is not only important to understand the chirality phenomenon, but also valuable for the development of new chiral drugs and chiral catalysts.

手性配合物由于在不对称催化、非线性光学和手性分离等方面有着广泛的应用而越来越受到人们的关注。然而，目前关于配合物手性与其手征结构单元之间的关系和结构规律却知之甚少，制约了有关学科的发展，特别是对手性现象的理解和手性调控方面。我们最近的工作表明，分子手性与其手征结构单元的贡献之间存在着一种加和关系。本项目拟对这一问题继续进行深入系统的理论研究，并以新近发现的一类钌苯配合物的构型自发反转现象为重点，通过热力学和动力学理论计算，分析其自发反转的机理和条件，探讨实际用于类似配合物全自发拆分的可能性。同时，改进现有的理论模型和参数化方案，编制定量解析复杂大分子圆二色谱的计算机程序，为简化配位聚合物等复杂体系的手征光学性质和结构分析奠定基础。这一研究不仅对于解决手性理论中的一些基本问题具有重要的科学意义，而且对于开发研究新的手性药物和手性催化剂等也具有重要的指导价值。

本项目中，我们按计划首先针对Co-EDDA类配合物，研究了其ECD谱的环尺度效应和N邻位效应，在此基础上提出了反常N邻位效应的概念，并结合Co-ED3A类配合物，研究了其起源和机理。此外，对Co(en)2(X)2类配合物系统研究了单齿配体X对ECD的影响，发现单齿配体的存在不仅会明显降低构型手性(Δ/Λ)对ECD谱的贡献，且非轴对称单齿配体的相对取向(δ/λ)还决定了ECD谱的符号和强度，即这种构象手性决定了配合物的手征光学性质。这一结果不仅颠覆了构型手性决定配合物ECD谱的传统认识，有关分析对理解配合物手征光学性质的起源也具有重要的理论意义。.此外，系统地研究了钌苯和一系列钌二亚胺类配合物在光照下三重态势能面上金属中心手性构型的反转机理，发现后者的主过渡态几何虽然与第三配体无关，但所涉及的3MC态和辅过渡态的数目与构型却与第三配体有关。这不仅对理解光致手性构型的异构化具有重要理论意义，而且对利用这一现象进行手性调控，实现单一手性配合物的合成也具有重要参考价值。