Synthesis And Gases Sorption Performances Of Several Acylamide-modifiedmulticarboxylate Copper-based Metal-organic Frameworks

Metal-Organic Frameworks?MOFs?,as a new type of porous material,have developed rapidly in recent decades and have attracted wide attention from scholars in the fields of chemistry and materials.MOFs material is generally made of metal ions?metal ion clusters?and organic ligands self-assembled into porous materials with periodic mesh skeleton;the metal ions belong to transition metal and organic ligands are oxygen,nitrogen and organic carboxylic acid ligands.It is different from the traditional inorganic porous materials,but also different from the general organic complexes.MOFs material not only has the characteristics of adjustable pore size,high specific surface area,chemical stability and thermal stability,but also because of these excellent physical and chemical properties,the material is stored in gas.Gas selective adsorption and separation have inestimable application potential.Recently,CO as the main emissions gas of fossil fuel combustion and the main components of greenhouse gases is waitting to be resolved.Therefore,it is of great significance to design and synthesize MOFs with high CO adsorption performance.In this paper,we have designed and synthesized six asymmetric polydentate carboxylic acid ligands,including three amide-modified tetracarboxylic acids.An amide-modified hexacarboxylic acid and a hexacarboxylic acid containing benzyl amino acid,H₄L₁,H₄L,H₄L₃,H L,H₆L₁ and H₆L,under certain conditions,self-assembled with the paddle-like[Cu?COO?₄]secondary structure unit to obtain six crystals of different shapes;and named HNUST-7,9,10,13-15?HNUST=Hunan University of Science and Technology?.The structures of HNUST-7 and HNUST-13 are determined by using X-ray single crystal diffractometer.The structures of HNUST-7 and HNUST-9 are both NbO-topology,non-interspersed three-dimensional spatial skeleton structure.The HNUST-13 structure is a three-dimensional skeleton structure of the eea topology connected with two nodes.In addition,the structure and gas storage performance of HNUST-7 were also characterized and studied.HNUST-7 could maintain the same skeleton structure after removing the guest molecules.It is also found that HNUST-7 has relatively large BET surface area and pore volume,and it has good adsorption ability to CO,which could contribute to the strong dipolar quadrupole interaction between the amide groups and CO.In addition,the breakthrough experiments on HNUST-7 show that its good gas selectivity.It is shown that inserting the polar amide group into the skeleton structure of the organometallic frame material can not only keep the material with high specific surface area and large pore volume.It can also improve the adsorption performance of CO and the selectivity of mixed gases.This paper is not only useful for the synthesis of organometallic frame materials with high specific surface area,but also can be used as a reference for the synthesis of organometallic frame materials with high specific surface area.It also provides some ideas for the synthesis of organometallic frame materials with mixed gas adsorption and separation.