Metal-organic frameworks lickety-split

Metal-organic frameworks (MOFs), with their high porosities and tailor-made molecular cavities, have been broadly pursued for a variety of applications, including hydrogen storage, catalysis, and nonlinear optical materials. One limitation has been the ability to prepare MOFs quickly--most syntheses require heating solutions a full day or longer. Richard I. Masel and Zheng Ni of the University of Illinois, Urbana-Champaign, have devised a rapid microwave-assisted MOF synthesis that allows the materials to be prepared in under a minute (J. Am. Chem. Soc., DOI: 10.1021/ja0635231). The researchers made three known MOFs by dissolving millimolar amounts of Zn(NO₃)₂·6H₂O and 1,4-benzenedicarboxylate in N,N′-diethylformamide solvent, sealing the solution in a glass vial, then heating the vial in a microwave synthesizer. Micrometer-sized cubic crystals of the zinc-based MOFs formed in as little as 25 seconds and were recovered by centrifugation and rinsing. Smaller cubic particles with smoothed edges were obtained by lowering the concentration of the solution.