Ionothermal synthesis of 3D zinc coordination polymer: [Zn2(BTC)(OH)(I)](BMIM) containing novel tetra nuclear building unit

A novel coordination polymer, [Zn2(BTC)(OH)(I)](BMIM) (H3BTC = 1,3,5-benzenetricarboxylic acid and BMIM = 1-butyl-3-methylimidazolium), is synthesized from the ionothermal reaction (160 °C, 5 days) of Zn(NO3)2 and H3BTC in 1-butyl-3-methylimidazolium iodide ([BMIM]I) ionic liquid and is structurally characterized. The structure exhibits a three-dimensional framework constructed from tetra nuclear building unit [Zn4(OH)2(I)2(CO2)6], which is the first appearance in zinc coordination polymers. The imidazolium cation [BMIM]+ of the ionic liquid acting as charge compensating agent has strong interactions with the framework. This compound is thermally stable up to ca. 300 °C based on TGA.