A novel open framework zincophosphate: Synthesis and characterization

Abstract

The crystallization of a reactive zincophosphate gel (which may contain Co(ll) component) in the presence of sodium cations at ambient temperature and pressure yielded products (abbreviated ZnPO-HEX or CoZnPO-HEX) with a novel anionic open framework topology. The Co(ll) ions isomorphously replace zinc(ll) in this zincophosphate lattice up to 30%. The hopeite phase appears as a precursor in the crystallization of these new products. The single crystal structure determination of CoZnPO-HEX reveals that the structure belongs to the hexagonal P61 space group with unit cell parameters a = 10.447(3) and c = 15.049(5) A. The structure consists of a three-dimensional tetrahedral framework containing one-dimensional six-ring channels. An in finite helix built up of sodium cations and water molecules has been found inside the channel. The helix plays an important structural role because a complete dehydration of the materials is the cause for the transformation of the hexagonal structure to an unknown crystalline phase.