An Ionothermal Synthetic Approach To Porous Proton-Conducting Polyoxometalate-Based Metal-Organic Frameworks

In this work, we obtained three polyoxometalate（POM）-based organic-inorganic compounds, using the ionic liquid 1-ethyl-3-methyl- bromide imidazole（Bmim） as solvent, and the different POMs as the basic building blocks, together with the copper ions and different organic ligands, successfully. By adjusting the reaction temperature, pH of the solution, etc., the optimum reaction conditions was explored out for synthesizing the POM-based organic-inorganic compounds with novel structure and excellent properties. Subsequently, the structure of these compounds were characterized by X-ray single crystal diffraction, elemental analysis, inductively coupled plasma emission spectroscopy, Raman spectroscopy, infrared spectroscopy, ultraviolet-visible spectroscopy, thermal analysis, high-resolution mass spectrometry, electrical ChemStation. Preliminary studies of the gas adsorption properties, proton conductivity and ion exchange properties of these compounds were carried on.1. A novel porous proton-conducting POM-based metal-organic frameworks（PMOFs）, TBA[（Cu^IBBTZ）₃Mo₈O₂₆],（TBA = tetrabutylammoniumcation, BBTZ = 1,4-bis（1,2,4-triazol-1-ylmethyl）-benzene） has been obtained ionothermally, using the octamolybdates as the basic building blocks, tetrabutyl ammonium cations as the template, together with the transition metal copper ions and organic ligands BBTZ. Furthermore, the properties of proton conductivity, N₂, H₂ and CO₂ adsorption and ion-exchange properties of the compounds have been investigated in this paper, carefully.2. Two novel 3D supramolecule architectures based on hexamolybdate and phosphotungstate anions were obtained under the ionothermal condition successfully: [Cu^I（L1）₂]₂L2[Mo₆O₁₉]（2）, [Cu^I（L3）₂]₃[PW₁₂O₄₀]· H₂O（3）,（L1 = 2,2’-bipyridine, L2 = 4,4’-bipyridine, L3 = 2,2’-biimidazole）, and characterized by FI-IR and Raman spectroscopy. Single-crystal X-ray diffraction analysis reveals that these two compounds both crystallized in the space group P-1 and conformed through hydrogen bonding interactions, the free organic ligands occupied in the channel conformed by the supramolecule architectures.