The multifunctional design of metal-organic framework by applying linker desymmetrization strategy: synergistic catalysis for high CO2-epoxides conversion

Herein, a novel copper metal-organic framework (Cu-MOF), [Cu2(CPTPTA)(H2O)]·CH3NH3+·4H2O·7NMF (1) (H5CPTPTA = 5'-(4-carboxyphenyl)-[1,1':3',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid, NMF = N-methylformamide), has been successfully synthesized via solvothermal reaction. By applying linker desymmetrization strategy, compound 1 was constructed by a reduced symmetry ligand CPTPTA5-, leading to three types of channels with various functional sites. Meanwhile, the functional sites promoted the adsorption of CO2, the uptakes are 123.2 and 66.8 cm3 g-1 at 273 and 298 K, respectively. Furthermore, the smaller channel exists two kinds of active sites: Lewis acid sites (LASs) and Bronsted acid sites (BASs), whereras the larger one only exists LASs. The synergistic catalysis of LASs and BASs makes compound 1 exhibit excellent CO2 cycloaddition efficiency towards propylene oxide (PO), and the yield can reach up to 97 %. Overall, such a linker desymmetrization strategy can afford an effective approach on synthesizing novel functional MOF materials.