Ionothermal synthesis of a 3D Zn–BTC metal-organic framework with distorted tetranuclear [Zn4(μ4-O)] subunits

A zinc metal-organic framework (MOF), [Zn4(BTC)2(μ4-O)(H2O)2], was synthesized with Zn(NO3)2 · 6H2O and H3BTC ligand (H3BTC = 1,3,5-benzenetricarboxylic acid) by ionothermal synthesis in 1-ethyl-3-methylimidazolium bromide ionic liquid as solvent. The compound features a 3-D architecture constructed by linking [Zn4(μ4-O)] subunits with BTC3− ligands. They are composed of two five-coordinated and two four-coordinated Zn ions, different from the [Zn4(μ4-O)] units of other MOFs. The effect of reaction conditions to the MOF structure is discussed.