Ultrasonic synthesis of the microporous metal–organic framework Cu3(BTC)2 at ambient temperature and pressure: An efficient and environmentally friendly method

A three-dimensional (3-D) metal–organic framework (MOF) with 3-D channels, i.e. Cu3(BTC)2 (HKUST-1, BTC = benzene-1,3,5-tricarboxylate), was synthesized by using ultrasonic method for the first time. The reaction of cupric acetate and H3BTC in a mixed solution of DMF/EtOH/H2O (3:1:2, v/v) under ultrasonic irradiation at ambient temperature and atmospheric pressure for short reaction times (5–60min) gave Cu3(BTC)2 in high yields (62.6–85.1%). These Cu3(BTC)2 nano-crystals have dimensions of a size range of 10–200 nm, which are much smaller than those synthesized using conventional solvothermal method. There were no significant differences in physicochemical properties, e.g. BET surface area, pore volume, and hydrogen storage capacity, between Cu3(BTC)2 nano-crystals prepared using ultrasonic method and the microcrystals obtained by using improved solvothermal method. Compared with traditional synthetic techniques, such as solvent diffusion technique, hydrothermal and solvothermal methods, ultrasonic method for the construction of porous MOFs was found to be highly efficient and environmentally friendly.