Design And Synthesis Of Functional MOFs And Study On Catalytic CO₂ Conversion

Metal-organic frameworks(MOFs)can be employed as excellent heterogeneous catalysts because of their high surface area,rich designability and potential unsaturated metal sites etc.In this thesis,5,10,15,20-tetra(pyridin-4-yl)porphyrin(TPyP-H2)and 4-(4H-1,2,4-triazol-4-yl)benzenesulfonic acid(HTBS)ligands were chosen as the organic linkers to construct three unprecedented MOFs(TPyP-H2:1 and 2;HTBS:3),which have been fully characterized by single crystal X-ray diffraction,powder X-ray diffraction,infrared spectroscopy,raman spectroscopy and gas adsorption etc.Furthermore,the employment of these MOFs as heterogeneous catalysts for carbon dioxide fixation was comprehensively studied.The main works of this paper are as following:(1)By using TPyP-H2 ligand as an organic linker,one two-dimensional Ag27-TPyP(1)has been successfully constructed.Compound 1 features exposed metal sites in the saddle-shaped structure,which not only significantly enhances the stability of the silver cluster,but also facilitates the acti vation of organic substrates and the disassociation of products and thus improve the catalytic performance.The catalytic study illustrated that 1 readily catalyzes the CO2-cycloadditions of both terminal and internal N-propargylamines effectively under ambient conditions,representing the first example of metal cluster-based 2D MOFs as heterogeneous catalysts for CO2 fixation.(2)By using TPyP-H2 as an organic ligand,one three-dimensional Zn-TPyP(2)has been prepared,which features catalytic sites and exhibits an excellent catalytic performance in fixation of carbon dioxide to cyclic carbonates.This heterogeneous catalyst recycled at least four successive times with a slight decrease in the catalytic activity.(3)Under hydrothermal conditions,one stable Ag-TBS(3)was self-assembly synthesized from the reaction of HTBS ligand with silver salt.This MOF material exhibits high thermal stability and solvent stability.Similar to 1,it can promote the cyclization of propargyl amine and carbon dioxide at room temperature.