Lonothermal syntheses of six three-dimensional zinc metal-organic frameworks with 1-alkyl-3-methylimidazolium bromide ionic liquids as solvents

We have performed ionothermal reactions between Zn(NO3)(2) and H3BTC in 1-alkyl-3-methylimidazolium bromide ionic liquids with-the alkyl group varying from ethyl to amyl. Six 3-D metal-organic frameworks (MOFs), including two isomeric compounds [Zn-3(BTC)(2)(H2O)(2)]center dot 2H(2)O (1 and 2) (H3BTC = 1,3,5-benzenetricarboxylate acid), [EMI]-[Zn(BTC)] (3) (E = ethyl, MI = 3-methylimidazolium), [PMI][Zn(BTC)](4) (P = propyl), [BMI](2)[Zn-4(BTC)(3)(OH)-(H2O)(3)] (5) (B = butyl), and [AMI][Zn-2(BTC)(OH)Br] (6) (A = amyl), have been synthesized and structurally characterized. Compounds 1 and 2 are isomeric compounds, in which the coordination modes of Zn atoms and the BTC3- ligands are considerably different. Compounds 3-6 crystallize with the corresponding ionic liquid cations incorporated in the frameworks. Their crystal structures show various features including various coordination geometries of Zn2+ and various bridging modes of the BTC3- ligands. The incorporated cations appear to have strong interactions with the frameworks.