Mechanochemical Synthesis,Post-synthesis And Properties Of Hierarchically Porous MOFs

Metal Organic Frameworks(MOFs)are coordination compounds composed of metal ions or metal clusters and organic ligands.Due to their large specific surface area,structural diversity and tunable pore channels,it has extensive application prospects in sense,drug delivery and biological imaging.Meanwhile,the construction of hierarchically porous MOFs is attracting considerable attention because their tunable porous structures eliminate the pore restriction in microporous MOFs and increase the amount of active adsorption sites,thus improve the bulky molecules accessibility and catalysis,or introduce new properties.In this paper,salt(sodium chloride,potassium chloride)was chosen as a template and solid solvent to synthesize HKUST-1 with hierarchical pore structure under the mechanochemical method,using trimellitic acid H3BTC and copper acetate monohydrate Cu(OAc)2·H2O as raw materials.Meanwhile,chemically the addition of TED to the hierarchically HKUST-1 improve the uptake efficiency of iodine vapor.At the same time,this article also tried to synthesize micro nesopore ZIF-8 with SDS,and post-modified HKUST-1 with HMTA.We used NaCl as a solid solvent and template to assist an efficiently mechanochemical synthesis and postsynthesis of hierarchically micro-,meso-and even macroporous MOFs.The whole process was carried out stepwise in one-pot.This entire mechanochemical reaction can be divided into four steps:(1)pre-mixing each reactant with NaCl by ball milling for 1 minute;(2)mixing the resulting NaCl solid solution of each reactant together and then grinding for 20 minutes;(3)further grinding with TED for an additional 20 minutes;(4)simply ethanol and water rinsing,dry under vacuum.By adjusting the amount of NaCl and TED added,the type of pores,the ratio of these pores,the pore size and the grafting number of the functional molecules in MOFs are all controlled.The ratio of the number of mesopores and macropores obtained in this paper to the number of micropores reached to 25%,overcoming the micropore size limitations of HKUST-1.Notably,hierarchically MOFs have enhanced adsorption ability of dyes,and salt-assisted mechanochemically post-synthesized MOFs show more promising performance on iodine vapor capture than the solvothermally-synthesized product.The iodine vapor adsorption efficiency of our post-synthetic modified sample reached to 114.1%at 100?,which was significantly higher than that of 93.8%iodine vapor adsorption efficiency obtained by the solvothermal method.We believe that this simple and efficient salt-assisted grinding can be generally applied for the synthesis and postsynthesis of other hierarchical porous MOFs or other porous materials,and then enhance their applications in catalysis,adsorption,etc.