Zeolitic metal azolate frameworks (MAFs) from ZnO/Zn(OH)2 and monoalkyl-substituted imidazoles and 1,2,4-triazoles: Efficient syntheses and properties

Acid-base neutralization reaction between monoalkyl-substituted azole derivatives and ZnO/Zn(OH)(2) can be effectively activated by aqueous ammonia to synthesize a series of metal azolate frameworks (MAFs) including SOD-[Zn(mim)(2)](MAF-4, Hmim = 2-methylimidazole), ANA-[Zn(eim)(2)](MAF-5, Heim = 2-ethylimidazole), SOD-[Zn(mtz)(2)] (MAF-7, Hmtz = 3-methyl-1,2,4-triazole), dia-[Zn(mim)(2)] (MAF-31), qtz-[Zn(eim)(2)](MAF-32), and dia-[Zn(etz)(2)] (MAF-33, Hetz = 3-ethyl-1,2,4-triazole). The porous zeolitic MAFs obtained by this reaction possess high stability and can be easily activated. Their high porosity, unique pore size/surface characteristic, and framework flexibility were demonstrated by gas and solvent vapor (water, methanol, and benzene) sorption measurements. The imidazolate frameworks MAF-4 and MAF-5 are highly hydrophobic adsorbents with exceptional organic/water selectivity, while the triazolate framework MAF-7 containing uncoordinated nitrogen donor on the pore surface exhibits higher sorption affinity and lower stability. Despite the very small aperture sizes (3.2-3.4 angstrom), the SOD frameworks can readily adsorb large organic molecules by temporary distortion of the structure. (C) 2011 Elsevier Inc. All rights reserved.