Zeotype ionic crystal of Cs5[Cr3O(OOCH)6(H2O)3][alpha-CoW12O40].7.5H2O with shape-selective adsorption of water

A polyoxometalate-macrocation ionic crystal of Cs5[Cr3O(OOCH)6(H2O)3][alpha-CoW12O40].7.5H2O (1a) was synthesized by the complexion of an inorganic metal-oxide cluster of [alpha-CoW12O40]6- and a macrocation of [Cr3O(OOCH)6(H2O)3]+. About 50% of the water of crystallization in 1a was desorbed by the evacuation to form phase 1b, and the crystallinity and crystal structure was essentially maintained by the transformation. 1b adsorbed water into the solid bulk but excluded larger alcohols. 1b was easily reusable for the separation of only water in the azeotropic mixture of ethanol and water.