基于手性AIE金属有机骨架的圆偏振发光性能的研究

Circularly polarized luminescence (CPL) is the differential emission of left or right circularly polarized light which has attracted wide attention for its applications in three-dimensional display, bio-probe, information processing and chiral photocatalysis. Dyes of metal complexes normally have large CPL dissymmetric factor, but low luminescence efficiency. Organic dyes have high fluorescence quantum yield, but low CPL dissymmetric factor. Those shortcomings inhibit the practical utilization of the CPL. In order to address the above issues, a novel approach based on metal-organic framework (MOF) of chiral ligands with aggregation-induced emission (AIE) was proposed. Chiral helical tetraphenylethylene (TPE) derivatives with aggregation-induced emission (AIE) are used to coordinate with metal ions to afford chiral metal-organic framework (MOF). In the chiral MOF, the helical TPE units are expected to be immobilized and organized in an orderly packing and orientation, which will improv the CPL performance. Meanwhile, the further immobilization of the phenyl rotation by coordinating to metal ions will increase the fluorescence intensity of the chiral AIE-MOF materials. Therefore, this novel approach has great potential to address the dilemma between dissymmetric factor and emission quantum yield of CPL. In this project, by jointing the AIE effect, helical chirality of AIE molecules and rigid structure of MOF materials, advances are expected towards new CPL materials display much improved properties and pave the load for practical applications. A serial of novel chiral AIE-MOF crystal materials are to be obtained which showed increased CPL dissymmetric factors. The mechanisms of CPL enhancement are also interesting to be disclosed. Fundamental breakthroughs and important results will be accomplished in this project.

圆偏振发光（CPL）可用于三维显示、生物探针、信息处理以及手性光催化等方面，引起了广泛重视。金属配合物通常具有大的CPL不对称因子，但往往发光效率低，许多有机分子具有高的荧光量子产率，但CPL不对称因子却一般很小，这些问题限制了CPL的实际应用。将具有聚集诱导发光（AIE）的手性四苯乙烯（TPE）螺旋体与金属离子配位，从而得到具有晶态有序结构的手性金属有机骨架（MOF），使TPE螺旋体在MOF晶态结构中进行固定、有序排列和取向，CPL性能有望得到提升；配位固定后，基于AIE效应的发光强度也将增加，从而同时提高CPL的不对称因子以及发光量子产率，解决CPL实际应用中存在的问题。本项目将AIE效应、螺旋手性与MOF的刚性结构结合起来，合成AIE手性MOF晶态材料，用于增强CPL性能，揭示增强的机理和规律，将取得具有重要科学意义及应用背景的创新性研究成果。

聚集诱导发光（AIE）化合物是其具有螺旋桨结构，在进行分子之间堆叠时，不会靠的太近而发生荧光淬灭（ACQ），而分子之间控制聚集状态及间隔距离，显得很困难和多变。四苯乙烯（TPE）及其衍生物，是AIE分子中的明星分子，本项目设计将四苯乙烯结构构筑到多孔材料中，实现材料荧光大幅增强，高效获得结构均匀的强荧光多孔材料。.我们主要进行四苯乙烯苯环结构双重限制，进而提高荧光强度，设计将四苯乙烯结构构筑在大环内再与离子络合，形成类似MOF结构堆叠体，以及将四苯乙烯掺杂到有机聚合物，两种方法得到荧光增强多孔材料。并进一步研究MOF材料中电子转移规律，从而探索强荧光MOF材料构筑新思路。.本项目特色及创新之处在于：1）设计合成四苯乙烯分子内固定的结构后，进行分子间连接成环，得到咪唑大环。再进行阴阳离子络合配位，形成二次固定限制，聚集体材料荧光大幅提升。证明TPE分子双重限定在MOF结构里时，材料荧光大幅提升。2）将TPE不经过官能团化，直接Scholl偶联反应锁定到高分子链中，形成多孔聚合物，由于聚合物在横向的限制作用，TPE分子被进行的分子内限定，荧光也大幅提升。为高效廉价获取强荧光多孔材料提供了新的路径。3）控制变量法合成不同配体结构MOF材料，研究晶体中，有机分子的电子转移规律，科学预测有机配体变化对MOF晶体荧光变化的影响。克服晶体获取周期长的难题，也为找到MOF结构中发光更优秀的有机配体提供了新思路。