晶态手性超分子配合物中手性的诱导与传递的研究

This research project is the exploration of the chirality inducement, delivery and succeeding amplification from molecules or structural motifs to three-dimensional crystal lattice, which is a key question to synthesize the chiral materials with novel physicochemical properties, for example, the chiral molecule-based magnet. Based on molecular energine, crystal energine and supramolecular energine, the research idea to solve the problem in this project is to rational design the chiral functional building blocks with molecular identification and stereo-hindrance functional group in initial step. Then, these chiral structural motifs will be self-assemblied in non-centeral symmetrical mode, that is a chiral supramolecular self-assembly. The factors to control the chiral supramolecular self-assembly are the identification and competition between different noncovalent bonding interactions, template effects of guest molecules such as cations and anions, the polarity and protonation of solvents and reaction conditions such as pH value. To study and understand the chirality transfer, structural tuning and synergetic effects of these factors in chiral supramolecular self-assembly to achieve chiral crystgalline materials with interesting magnetic properties are an important resarch aim of this project. There are two strategies to design chiral structural motifs. One is chiral coordination compounds that has chirality centered in ligand or centered in magnetic metal ions (triclelated octahedron coordiantion geometry). The other is achiral molecules with groups for selective noncovalent bonding interactions. The chirality inducement will be generated in situ in the process of self-assembly. The different guest molecules such as template and chiral auxiliary agents will be introduced to control the self-assembly to obtain the enantiomeric supramolecular coordination compounds. In order to propose and confirm the mechanism of chiral supramolecular self-assembly, the conformation change of structural motif in the solution will be detected dynamically and kinetically, combining with the crystal structures of the enantiomeric product that will be studied through the x-ray single crystal diffraction analysis. For the physicochemical properties of the enantiomeric supramolecular coordination compounds, the magnetic superexchange interaction at low temperature will be focus on. It is challenge to realize chiral molecule-based magnets because of the challenge in the introduction of magnetic order and natural optical activity spontaneously in crystal lattice. The research achievements will contribute to the chiral materials, coordination chemistry, supramoecular chemistry and crystal engineering.

本项目从分子对称性和晶体对称性的角度，以手性分子磁体为功能导向，设计合成具有各种分子识别作用和空间位阻效应的手性功能基元。运用分子工程、晶体工程和超分子工程将这些手性功能基元组装成为晶态手性超分子配合物。探索手性超分子自组装的可控组装条件、途径和规律。研究非共价相互作用、客体分子以及反应条件在手性超分子自组装过程中的结构导向、调控和协同作用，实现手性的诱导、传递和放大。研究结构基元的手性与物质的宏观手性之间的关系。结合自组装体系溶液中结构基元的构象转化的研究和晶态手性超分子组装物的晶体结构的分析，提出手性超分子自组装的机理。探索晶格中的宏观手性与磁有序之间的关系，将光学活性和磁有序性自发地、协同地融合在手性超分子配合物中，为手性分子磁体的应用奠定基础。

手性问题是化学、生命科学和材料科学领域中一个非常基础而又受到广泛关注的科学问题。项目以核苷酸为手性配体，运用分子工程、晶体工程和超分子自组装研究了核苷酸晶态手性超分子配合物。探索了手性超分子自组装的可控组装条件、途径和规律。研究了非共价相互作用、辅助配体、客体分子以及反应条件在手性超分子自组装过程中的结构导向、调控和协同作用，实现了手性的诱导、传递和放大。研究了结构基元的微观手性与物质的宏观手性之间的关系。结合自组装体系溶液中结构基元的构象转化的研究和晶态手性超分子组装物的晶体结构的分析，提出了手性超分子自组装的机理。通过本项目的研究，总共设计并合成了近百种新型的核苷酸配合物以及配位聚合物，特别是对其中的50多种运用X-射线单晶衍射技术研究了它们的单晶结构，这是目前认识与研究手性超分子组装模式及其手性问题的最有效手段之一。在其他研究手段，如红外光谱（IR）、紫外可见光谱（UV-vis）、元素分析、热重（TGA）、X-射线粉末衍射、溶液与固态圆二色谱（CD）等的辅助下，对这些配合物进行了全面的结构表征和手性分析。由于核苷酸及其相关化合物的结晶是结晶化学与晶体学中的一个难题，因此，本项目中所取得的研究成果对核苷酸晶体学是一重要贡献。本项目的创新点之一就在于运用这些难得的单晶结构数据与溶液和固态圆二色谱（CD）相结合的方法研究超分子手性；认识在这些晶态核苷酸手性超分子配合物中的分子手性、手性诱导、手性传递与手性放大。本项目的另一创新点是首次认识到一种新型的一维配位聚合物的手性构象，定义其为拓展轴手性，这是创新性地将有机化学中的轴手性概念发展到配位化学中。针对这些配合物的功能性质（如荧光性质等）进行了初步的探索，为进一步拓展核苷酸配位超分子组装体的应用奠定了基础。本项目的成果对核苷酸的配位化学与超分子化学以及功能超分子手性组装体的研究都有重要的理论意义。