Synthesis And Gases Sorption Performances Of Acylamide-modified Metal-organic Frameworks

Metal-organic frameworks(MOFs)are organic-inorganic hybrid materials that are different from traditional inorganic porous materials and are also different from common organic complexes.MOFs not only have a large surface area and pore volume,but also can be adjusted in pore size,structure and properties by modifying the organic or inorganic parts,which has great application prospects in gas storage and adsorption separation.Recently,CO2 as the main emissions gas of fossil fuel combustion and the main components of greenhouse gases is waitting to be resolved,so the development of high CO2 adsorption performance MOFs is very significant.In this paper,three asymmetric,amide-modified multidentate carboxylic acid ligands,H4 L,H6L1 and H6L2,were designed and synthesized.Among them,H4 L is a tetracarboxylic acid ligand modified by acylamide,which was reacted with paddle wheel-shaped [Cu2(COO)4] secondary building units(SBUs),and the Nb O-topological type and non-interspersed porous coordination polymer were obtained,temed HNUST-10(HNUST = Hunan University of Science and Technology);H6L1 and H6L2 are two hexacarboxylic acid ligands modified by one acylamide group and two acylamide groups respectively.both of them and paddle wheel-shaped [Cu2(COO)4] secondary structural unit under certain conditions,by self-assembly,got two rht-type topology,non-interspersed porous coordination polymers HNUST-11 and HNUST-12.We use a series of means to characterize and study their structures and gas storage performance.These three porous coordination polymers retain the original framework after removal of the guest molecules,and both have a large BET specific surface area.The structure and gas storage performance of three MOFs were characterized and studied by a series of tests.These three porous coordination polymers retain the original framework after removal of the guest molecules,and both have a larger BET specific surface area.By comparing HNUST-11 and HNUST-12 we have found that HNUST-11 and HNUST-12 have the same topological structure,HNUST-12 has a larger pore size and specific surface area than HNUST-11,but under the same conditions HNUST-12 exhibits greater CO2 adsorption capacity,higher CO2 enthalpy and better CO2 / N2,CO2 / CH4 gas adsorption selectivity than HNUST-11.It is shown that decoration of a MOF with polar acylamide groups can not only keeps the material in high surface area and large pore volume,but also significantly enhance the CO2 binding ability and selectivity of MOFs.This paper not only has a certain reference significance for the synthesis of porous coordination polymers with high specific surface area,but also provides some ideas for the synthesis of mixed gas adsorbable metal-organic frameworks.