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Facile Purification of Porous Metal Terephthalates with Ultrasonic Treatment in the Presence of Amides



A facile purification method for metal–organic frameworks (MOFs), especially the ones containing insoluble 1,4-benzenedicarboxylic acid (terephthalic acid) in the pore, has been suggested. The purification method consists of the treatment of the MOF with amides such as N,N-dimethylformamide, especially under ultrasound treatment. The purification is completed within 1 h at 70 °C as has been confirmed by XRD, nitrogen adsorption, FTIR and TGA measurements. The purification method proved to be simple, one-step, fast and energy-efficient. The MOFs purified by the proposed method show high surface area and micropore volume, confirming the efficiency of the method. The proposed method will lead to a new access to activate (for example, to remove carboxylic acids) MOFs that are unstable above around 100 °C. Additionally, the method may be used to transform a non-porous MOF-type material into a porous MOF structure. However, adequate solvents will be necessary for the facile purification of MOFs.