From crystal to crystal: a new polymorph of (4-carboxylatopyridine)silver(i) by topotactic dehydration of its monohydrate

Abstract

The dehydration of the coordination polymer (4-carboxylatopyridine)silver(I) monohydrate to a new polymorph of the unsolvated compound occurs even at room temperature under vacuum. In the course of this conversion, space filling increases; the new polymorph is closer packed than the one described earlier in the literature. The reaction proceeds as single-crystal-to-single-crystal transformation, with a close three-dimensional relationship between reactant and product crystals. The dehydration may also be conducted in the bulk, leading to a phase pure product. During the topotactic desolvation, the 3D framework of the monohydrate transforms into a two-dimensional layer structure. The reaction is irreversible: crystals of the unsolvated polymer cannot be re-hydrated when exposed to humid atmosphere or even immerged into water.