基于吡啶鎓多羧酸两性离子刚性配体的功能配位聚合物

Metal-organic coordination polymers provide an important and versatile platform for the development of functional materials and the exploration of underlying science, and the study has become a hot topic in the fields of coordination chemistry and materials science. This project is devoted to constructing coordination polymers using rigid and pyridinium-based zwitterionic multicarboxylate ligands, investigating their porosity and optical and magnetic properties, and exploring new magnetic-based multifunctional materials. (1) Novel rigid zwitterionic multicarboxylate ligands in which aromatic carboxylate and pyridinium/bipyridinium units are bonded directly will be synthesized. The underlying law controlling the assembly of coordination polymers (especially porous ones) will be explored, and particular efforts will be made to reveal how the skeleton charge of the multicarboxylate ligands and the presence of anionic coligands influence the structure of coordination polymers. The host-guest chemistry based on the electron-accepting properties of pyridinium groups will be a focus of the study. (2) Pseudohalide or hydroxo anions will be introduced as co-ligating agents to construct magnetic coordination polymers that contain extended bridging networks for magnetic exchange between metal ions. This approach will lead to molecular magnets and especially single-chain magnets. Guest-responsive porous magnetic materials will be studied by combining porosity and magnetism in one system. (3) The photochromic and photomagnetic properties of the coordination polymers will be investigated, and particular attention will be paid to the compounds with paramagnetic metal ions, where the interplay between the photomagnetic bipyridinium moiety and paramagnetic metal ions should influence the long-range magnetic ordering and single-chain magnetism. The study can establish novel systems for the exploration of photomagnetic materials. The composition-structure-properties relationship will be discussed.

金属-有机配位聚合物为功能材料的开发及相关科学规律的探索提供了非常有用的平台，其研究是当前配位化学和材料科学的热点之一。本项目利用含正电性吡啶鎓受体功能单元的两性离子多羧酸刚性配体构筑配位聚合物，研究其光、磁性质，并以磁性为主探索多功能复合。(1)设计刚性的芳香羧酸单元与吡啶鎓或联吡啶鎓直接键联的新型两性离子多羧酸配体，构筑配位聚合物，探讨其结构组装规律，并基于吡啶鎓单元的电子受体性质研究主客体化学；(2)引入类卤素、氢氧根等共配阴离子以构筑含扩展磁交换网络的磁性配位聚合物，获得分子磁体尤其是单链磁体，并结合多孔性获得具有客体响应性的多孔磁性材料；(3)基于联吡啶鎓的氧化还原性研究配位聚合物的光致变色和光磁性质，重点研究联吡啶鎓光-磁效应对磁性的调制或开光作用，探索新型光响应性分子磁性材料，认识其组成-结构-性能关系，建立光磁材料研究的新体系。

金属-有机配位聚合物或金属-有机框架(MOFs)为功能材料的开发及相关科学规律的探索提供了非常有用的平台。吡啶鎓化合物具有独特的电荷、电子结构，尤其是联吡啶鎓因其强缺电子性具有丰富的刺激响应性。本项目利用(联)吡啶鎓羧酸两性离子配体构筑配位聚合物或MOFs，研究其光、磁性质，尤其是利用联吡啶鎓单元的刺激响应性实现其光、磁性质的调节和控制，深入认识其组成-结构-性能关系，探索具有光/磁开关、传感功能的新型材料。主要研究内容和重要结果如下。. (1) 羧基-叠氮共桥磁性配聚物：利用吡啶鎓羧酸配体构筑了具有单链磁性的混金属配聚物，总结了羧基-叠氮共桥体系的结构组装趋势和磁构关系，发现了金属混合对单链磁驰豫的异常效应(协同和反协同效应)，为单链磁体弛豫调控提供一种新策略，尤其是指出了通过Co(II)-Ni(II)混合提高阻塞温度的新途径。. (2) 联吡啶鎓类化合物的新刺激响应性。首次发现了联吡啶鎓类化合物的压致变色、水致变色性质，深入阐述了其电子转移机理、水分子对光/压诱导固态电子转移的影响及配位结构对上述性质的调节作用。联吡啶鎓类化合物新变色性质的发现为开关/传感材料研究开辟了新体系。. (3) 具有刺激响应性的磁性配聚物。基于联吡啶鎓的电子转移变色倾向，获得在光照、加压或脱吸水后呈可逆磁性变化的配聚物，开辟了光磁、压磁及溶剂响应磁性研究的新体系。. (4) 具有丰富刺激响应性的变色/发光MOFs及其应用。获得具有独特缺电子孔结构的高稳定性稀土-4,4’-联吡啶鎓MOF，在光、压、溶剂、富电子阴离子/客体等刺激下呈现可逆的吸光(颜色)、发光双重响应，揭示了其电荷转移/电子转移/能量转移机理，实现了压力或其它手段调制的发光、水相苯胺/苯酚类污染物的超灵敏检测；由于类似机理，通过后合成季铵化策略获得的2,2’-联吡啶鎓功能化离子型Zr-MOFs具有丰富刺激响应性，可用于水相阴离子或脂肪胺的比色/荧光/电化学检测和逻辑电路模拟；提出”IDA-in-MOF”策略，首次将指示剂位移分析(IDA)概念应用于MOF传感研究，将荧光淬灭式传感转化成荧光开启式，极大地提高了检测灵敏度，并阐明了其竞争电荷转移机理和“空间限域”效应。上述结果有助于深入认识MOF孔内的超分子化学，并为MOF传感材料开发提供了新思路。