Design,Synthesis And Adsorption Properties Of High Stable Metal-Organic Frameworks

As a class of emerging materials,porous materials are widely used in industrial production.Metal-Organic Frameworks（MOFs）,as a new type of highly ordered porous crystalline materials,have become a research hotspot of many international researchers.Compared with traditional inorganic porous materials,MOFs features flexible ligands,diversified metal nodes,large specific surface area,and adjustable structure,which have great potential applications in adsorption,separation,catalysis,and energy technologies,etc.To synthesize the structure-and function-oriented MOFs to realize the application in the field of adsorption,the rational design of inorganic metal center and organic ligand is very important.For synthesize the high stable MOFs with excelent adsorption capacity for heavy metal ions,light hydrocarbons,and dye molecules,we selected specific inorganic metal centers and designed organic ligands with different conformation and functionalization.Then five functional MOFs were synthesized by optimizing synthesis strategy and reaction conditions.The basic characterization,adsorption properties of light hydrocarbons,heavy metal ions and dye molecules were further tested.The main research are as follows:（1）The tetracarboxylic ligand 2,2’-dimethyl-4,4’-diamino-3,3’,5,5’-tetra（4-carboxyl phenyl）biphenyl（H₄DCBA-CH₃）and 2,2’-ditrifluoromethyl-4,4’-diamino-3,3’,5,5’-tetra（4-carboxyl phenyl）biphenyl（H₄DCBA-CF₃）were designed and synthesized by functionalize the ligand 4,4’-diamino-3,3’,5,5’-tetra（4-carboxyphenyl）biphenyl（H₄DCBA）with methyl and trifluoromethyl,respectively.Finally,two Zr-MOFs（UPC-48,UPC-49）were synthesized by self-assembled ligand with Zr₆ cluster.The modification of functional groups endows the ligand with more flexible conformation,thus changing the topologies of MOFs.UPC-48 and UPC-49 shows high hydrothermal and chemical stability and exhibit excelent adsorption capacity and adsorption rate for Cr₂O₇^2-.In addition,the functional groups further improve the adsorption/separation capability for light hydrocarbons.（2）By functionalize the ligand 3,3’,5,5’-tetra（4-carboxyphenyl）biphenyl（H₄L）with methyl,the tetracarboxylic ligand 3,3’,5,5’-tetra（4-carboxylphenyl）bimesityl（H₄TB）was successfully designed and synthesized.Then the UPC-50 was synthesized by assembly with Zr₆ cluster.UPC-50 features excelent hydrothermal and chemical stability,which can be stable in nitrogen atmosphere at 400°C and in aqueous solutions of p H=1-12.The Zr-OH bond in the Zr₆ cluster and the unique pore environment enable UPC-50 with excelent adsorption capacity and adsorption rate for Cr₂O₇^2-.At the same time,UPC-50 exhibit a high adsorption selectivity for C₁-C₃ light hydrocarbons owing to the unique porous structure.（3）Based on the ligand[1,1’:3’,1’’-terphenyl]-4,4’’,5’-tricarboxylic acid（H₃TTCA）,by replacing the part of benzene ring with C=C bond and functionalizing of the methyl and amino groups in benzene ring,the tricarboxylic ligand 3,3’-（5-carboxy-2-chloro-1,3-phenylene）diacrylic acid（H₃L-Cl）and 3,3’-（2-amino-5-carboxy-1,3-phenylene）diacrylic acid（H₃L-NH₂）were synthesized.Then the UPC-60-Cl and UPC-60-NH₂ were successfully constructed through self-assembled with Fe₃O cluster.UPC-60-Cl and UPC-60-NH₂ exhibit high hydrothermal stability.The complex channels and the modification of functional groups endows UPC-60-Cl and UPC-60-NH₂ with high light hydrocarbon adsorption capacity and C₂H₂/CO₂ separation capacity.Moreover,the synergistic effects of reasonable pore size and functional groups make UPC-60-Cl and UPC-60-NH₂ show excelent dye molecule selective adsorption capacity.