Solvent-Induced Structural Rearrangement in Ultrasound-Assisted Synthesis of Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are crystalline extended structures featuring permanent porosity, assembled from metal ions and organic ligands, often synthesized by the solvothermal method (50-260 °C, 12-72 h). Here, an alternative synthetic approach-solvent-induced structural rearrangement in ultrasound-assisted synthesis is presented. Six representative Zn-based MOFs, each composed of distinct secondary building units, are synthesized within 2-180 min consuming less solvent (>0.03 m) at room temperature. It is observed that ultrasonication induces the construction of a coordination network, and subsequent solvent exchange triggers structural rearrangement to yield MOFs of high crystallinity and porosity. Furthermore, the scalability of this method is demonstrated through the bulk synthesis of MOF-5, MOF-74, ZIF-8, and MFU-4l within 90 min. The initiation of nucleation through ultrasound and the subsequent transformation induced by solvent exchange offer an alternative method for efficiently synthesizing MOFs in bulk, potentially broadening their range of applications.