Synthesis And Catalytic Applications Of Metal-Organic Polymers Based On Zwitterionic Ligands

As a kind of emerging new materials, Metal-Organic Frameworks (MOFs) gradually become a hot research topic in coordination chemistry and materials science community because of their various topological structures and physical and chemical properties. Heterogeneous catalysis was one of the earliest proposed applications for MOF materials, as well as one of the earliest demonstrated applications. As they contain organic components, it’s easy to design and modify the cavity sizes, functional groups and active sites in MOFs. The synthesis of MOFs with specific catalytic activities for potential catalytic applications is an important research area. As an important synthetic method for functional MOF materials, the postsynthetic modification (PSM) strategy is widely used to develop the application fields of MOFs.Seven zwitterionic ligands,1,1’,1"-(2,4,6-trimethylbenzene-1,3,5-triyl)tris (methylene)tris(4-carboxypyridinium) bromide(H3TPABr3),2-(4-carboxypyridinium-1-yl)acetate (Hcmi),2-(3-carboxypyridinium-1-yl)acetate (Hcmn),2(1-(carboxy methyl)-benzoimidazol-3-ium-3-yl)acetate(Hcmb),3,3’-methylenebis(1-(4-carboxy phenyl)-1H-imidazol-3-ium) chloride(H2bmpcCl2),3,3’-methylenebis (1-(4-carboxy-2-methylphenyl)-1H-imidazol-3-ium) chloride(H2mmpcCl2) and3,3’-methylenebis (1-(3,5-dicarboxyphenyl)-1H-imidazol-3-ium) chloride(H4tmpcCl2) were designed and synthesized for the construction of15novel coordination polymers, which were characterized by single X-Ray diffraction analysis, PXRD, IR and TGA etc. Based on the crystal structures, we studied their optical properties. Moreover, three imidazole zwitterionic ligands based MOFs were post-modified for catalytic application. The post-modified solids present highly catalytic activities in Suzuki coupling, Heck coupling, hydrogenation of olefins and nitrobenzene reactions. Detailed experiments were carried out to optimize their catalytic results in these reactions.