Sonochemical Synthesis and Characterization of Submicrometer Crystals of the Metal–Organic Framework Cu[(hfipbb)(H₂hfipbb)_0.5]

Abstract

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 °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.