Metalation In Cage,Gas Adsorption And Catalysis Of Metal-Organic Polyhedra

Metal-organic polyhedra(MOPs)is a kind of organic-inorganic hybrid materials,which has a great application prospect in gas adsorption and separation,molecular recognition,drug transport,catalysis and other fields.MOPs have unique structure,the specific size of the cavity,as well as the characteristics of encapsulation the guest molecules in the cavity have attracted wide attention.However,MOPs still has many disadvantages,such as lack of rigid framework and difficulty metalation in cage,which restrict their application in the fields of gas adsorption and separation,catalysis and so on.In this paper,we firstly discovered by selecting appropriate terminal ligands is an effective way to the metalation in the cage of MOPs,and the functionalization of metal can significantly improve the skeleton rigidity,gas adsorption and catalytic performance of MOPs.Herein,we have synthesized six octahedral MOPs materials:[Cu12(CDC)12(DMA)6(H2O)6]·xS(S=non-coordinated solvent molecules)(1),[Cu12(CDC)12(Apz)2(DMA)4(H2O)6]·XS(2),[Cu12(CDC)12(Pz)2(DMA)6(H2O)4]·xS(3),[Cu12(CDC),2(Apz)2(DMA)4(H2AO)6Cu0.5(H2O)6]·xS(4),[Cu12(CDC)12(Apz)2(DMA)4(H2O)6Ni0.5(H20)6]·xS(5),[Cu12(CDC)12(Apz)2(DMA)4(H2O)6Zn0.5(H2O)6]-xS(6)with 9Hcarbazole-3,6-dicarboxylate.Apz,Pz,DMA are respectively aminopyrazine,pyrazine,N,N-dimethylacetamide.The total terminal ligands for DMA(1)and the partial ligands for Pz(3)can not functionalization in the cage of MOPs.The partial ligands for Apz(2)permit Ni2+,Cu2+,Zn2+ metal·ions into the cage of MOPs,forming 4,5 and 6,but the larger size of the metal ions(Ca2+?Sr2+?Ba2+?Co2+)can not enter the cage of MOPs,indicating that(2)has the selective recognition behavior of Ni2+,Cu2+,Zn2+ metal ions.By gas adsorption contrast,the specific surface area of 4-6 is 381.5,417.9,303.2 m2/g,which is much higher than 2,254.1 m2/g.The adsorption of CH4,C2H6,C2H4,C2H2 gases on compound 2 and compound 4 show that the cage metallization can improve the gas selectivity of MOPs.By IAST,the selectivity for C2H2/CH4 was 209.9 on compound 4,which was higher than the compound 2 of 142.5.At the same time,we tested the compound 1-6 catalytic styrene oxide ring opening reaction.The compound 4,5 and 6 have higher conversion on the styrene oxide ring opening reaction,after several times of recycling,compound 4,5 and 6 can still maintain high conversion.But compound 1,2,and 3 have reduced catalytic activity after multiple catalysis.Finally,this paper provides a simple and effective synthesis strategy for the cage functionalization of MOPs materials and a new idea for the application of functionalMOPs materials in the fields of gas storage and separation,catalysis and other fields.