由氟代芳香羧酸后合成修饰制备的手性配位聚合物及其在手性催化和分离中的应用

Porous chiral coordination polymers, emerging as a promising crystalline materials for asymmetric catalysis and separation, have received extensive attentions recently. This is because they have many outstanding advantages, such as larger surface areas, easily to be designed or modification, unique effect of nano confinement and host-guest interactions. However, there are some problems in the studies of chiral coordination polymers, including complex synthetic processes for enantiopure ligands, lack of chemical and thermal stability and difficulties in rational design of chiral active sites. How to graft more active sites for chiral catalysis and recognition, and ensure the stability and porous of structures simultaneously, is a great challenge in practical application of chiral coordination polymers. In this project, we choose fluorine substituted aromatic carboxylic acids and proper metal ions to build MOFs with stable structures and larger pores. Post-synthetic modification is adopted to introduce various types of chiral catalysts and recognition active groups, such as proline, amino acids or BINOL, in order to construct a new series of chiral coordination polymers with chiral active sites hanging inside the channels. Optimization the chiral catalyst and separation performances by judiciously adjusting the species and structures of the chiral groups, study the mechanism of catalysis and separation from molecular level, will finally obtain several effective and reliable chiral catalysts and separation materials. There are no report about chiral modification of MOFs based on fluorine substituted aromatic ligands by post-synthesis. This study will provide new theoretical and experimental basis for the immobilization of chiral catalysts and the practical application of novel chiral chromatographic stationary phases.

多孔手性配位聚合物因其较大的比表面积、优良的可修饰性、独特的纳米限域效应和主客体相互作用而成为近期备受关注的新型不对称催化和手性分离材料。然而目前手性配聚物存在配体合成繁琐、稳定性差、活性位点难以利用等问题。如何简便地引入更多手性催化和识别位点，并兼顾结构的稳定性，是制备高效稳定、可供实际应用的手性配聚物所面临的挑战。本项目拟以含氟刚性芳香羧酸和合适的金属离子构筑结构稳定的大孔径含氟配聚物，再通过后合成法在框架中嫁接氨基酸、BINOL等多种类型手性催化或识别单元，得到一系列结构新颖稳定、孔道内壁有由手性活性基团修饰的手性配聚物。通过调控手性基团的种类来优化手性催化及分离性能，从分子层面探讨不对称催化与分离作用机理，希望筛选出性能优良、可靠耐用的手性催化与分离材料。以含氟芳香羧酸MOF为前驱体的后合成研究尚无报道，本研究将为手性催化剂的固载化和新型手性色谱固定相的开发提供新的理论和实验依据。

在该基金的资助下，我们按照项目计划，取得了以下几方面的进展。（1）设计合成了系列由氟取代的对三联苯羧酸配体，并将其与金属离子构筑了一例含氟配位聚合物，研究了化合物的晶体结构和物理性能，为进一步的后合成修饰打下基础。（2）设计合成了系列氨基酸衍生物手性配体和一种含氮柔性有机配体，与铜离子反应构筑了四例手性配位聚合物。我们对上述材料进行了结构表征和拓扑分析，发现其中两例具有多孔三维结构。固态圆二色光谱研究表明所得材料均为单一手性。磁性分析表明该系列化合物所包含的典型的双核铜单元具有反铁磁性。其中一例化合物在除了甲醇以外的常见溶剂中稳定性好，并对N2，H2等气体展现出良好的吸附性能。该工作对设计手性MOF作为新型手性固定相有一定的指导意义。（3）采用一种氨基酸类手性配体与一种刚性含氮配体，与铜离子通过精确调控溶剂和化学计量比等反应条件，构筑了从零维到三维的三例手性配位聚合物。我们采用荧光光谱法研究了该系列化合物与鲱鱼精DNA的相互作用。结果表明其中一例化合物能使溴化乙锭-DNA复合物的荧光逐步淬灭，且降低幅度与所加入的化合物的浓度有良好的线性关系，说明化合物和DNA之间存在一定的相互作用。该研究为手性配位聚合物的抗肿瘤生物活性的研究提供了新思路。本项目研究期间共发表有该基金资助号的SCI收录论文5篇。