Sonochemical Synthesis and Characterization of Submicrometer Crystals of the Metal-Organic Framework Cu[(hfipbb)(H2hfipbb)0.5]

The metal organic framework (MOF) Cu(4,4'-hexafluoroisopropylidene-bis-benzoate)(1.5) (Cu-hfipbb) has been projected as an important new nanoporous material for fabricating membranes with applications in gas separation and CO2 capture, among others. Synthesis of submicrometer crystals of Cu-hfipbb, however, is impeded by several factors, including the extreme hydrophobicity of the hfipbb ligand. We report a fast synthesis of submicrometer particles of Cu-hfipbb via a sonochemical technique, at temperatures as low as 0 degrees C, and with the addition of 2-propanol to control the particle morphology. The particles were characterized by powder X-ray diffraction, thermogravimetry, light scattering, and electron microscopy to ascertain the effects of synthesis parameters on the size distribution, structure, and morphology. The presence of a small amount of 2-propanol substantially alters the particle morphology from needles to a more isotropic shape. The Cu hfipbb particles produced by this approach are suitable for use in applications involving fabrication of membranes and thin films.