Abstract
Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized.Com-pound 1[Th6(HPyC)8(HCOO)4]is formed by replacing formate ligands of preassembled thorium clus-ter[Th6O4(OH)4(H2O)6(HCOO)12]with eight H2PyC(4-pyrazolecarboxylic acid)under solvothermal con-ditions.Each of the HPyC-ligands is coordinated with one Cu2+to form the(4,8)-connected scu-net structure of compound 2[(CuCl2)2Th6(HPyC)8(HCOO)4].In compound 3[(CuCl2)2Th6(HPyC)10(HCOO)4],ten of the formate ligands of preassembled Th6 cluster are replaced by HPyC-ligands.Compared with compound 2,the two extra HPyC-ligands in the equatorial plane of the Th6 cluster in compound 3 are not further connected to copper ions.Therefore,the topology structure of compound 3 is same with that of compound 2.Compound 4[(Cu3Cl2)(CuCl2)Th6(PyC)3(HPyC)4(HCOO)5]contains three kinds of metal nodes,Th6 cluster,Cu3 cluster and mononuclear Cu2+,and exhibits a novel(5,7)-connected net struc-ture,which was first discovered in actinide MOFs.Furthermore,considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites,the catalysis of cycloaddition of CO2 was further studied.We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO2 conversion to value-added products.
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