Ionothermal Syntheses of Six Three-Dimensional Zinc Metal−Organic Frameworks with 1-Alkyl-3-methylimidazolium Bromide Ionic Liquids as Solvents

Abstract

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 [Zn3(BTC)2(H2O)2] x 2H2O (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[Zn4(BTC)3(OH)(H2O)3] (5) (B = butyl), and [AMI][Zn2(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.

catena-Poly[[octaaquabis(μ4-benzene-1,3,5-tricarboxylato)trizinc] tetrahydrate]

“…All the distances of Zn -O in compound (I) are comparable to those found in the literatures (Hua et al, 2010;Chen et al, 2010;Yang et al, 2008;Xu et al, 2007). And there are weak interactions between Zn1 and C1 with the distances of 2.554Å and Zn1 and H2WB with with the distances of 2.0711 Å.…”

“…And such ligand has been widely used to synthesize metal compounds (Yaghi et al, 1997;Xu et al, 2008;Xu et al, 2007;Liang et al, 2009;Wang et al, 2009). Thus, we synthesize a new three-dimensional Zn-BTC metal-organic compound, 4 }, with achiral channels along b direction, which was generated by the reaction of zinc sulfate heptahydrate, 1,3,5-benzenetricarboxylic acid and water at 150°C for 3 days.…”

Probing the Local Structure of Pure Ionic Liquid Salts with Solid‐ and Liquid‐State NMR

“…A broad spectrum of tunable properties arises from the customizability of the organic cation and the variety of cation-anion pairings and so ILs are often denoted as "designer solvents". Ionic liquids are finding uses as solvents and reaction media in a large number of diverse applications such as carbon dioxide sensors, [2] catalysis, [3,4] energy storage, [5] nanostructure synthesis, [6,7] and many others. Due to the enormous number of potential cation-anion combinations, it is impossible to investigate directly even a small fraction of the set of feasible ILs.…”

Crystal structure of bis(N-ethyl-N′-methylimidazolium)tetrabromozinc(II), (C6H11N2)2[ZnBr4]

“…ILs present us their excellent qualities such as negligible vapor pressure, tunable acidity, thermal stability, designable structures, nonflammability, awide liquid-state temperature range, and extended electrochemical windows, which leading to their potential applications in catalysis, electrochemistry, and solvent extraction, reaction media, nanomaterials and green chemistry [1][2][3][4][5][6][7][8] iii =3.813(3) Å,symmetry code iii: ½-x,½-y,½-z) [7]. These weak interactions lead to the formation of the 3D framework.…”