From an Open Framework to a Layered and a Hexagonal Tungsten Oxide Structure: Controlled Transformation Reactions of an Extended Solid-State Material, Cs3Ga7(SeO3)(12) to Ga(OH)(SeO3) and KGa3(SeO4)(2)(OH)(6)

Abstract

A highly symmetric open-framework gallium selenite, Cs3Ga7(SeO3)(12), containing cubic superlattices has been synthesized by a standard solid-state reaction using Cs2CO3, Ga2O3, and SeO2 as reagents. Cs3Ga7(SeO3)(12) exhibits a three-dimensional open-framework structure consisting of GaO4 tetrahedra, GaO6 octahedra, and SeO3 polyhedra. Step-by-step reactions of the solid-state material in aqueous KNO3 solution at different temperatures produce Ga(OH)(SeO3) with a layered structure and KGa3(SeO4)(2)(OH)(6) having a hexagonal tungsten oxide (HTO) topology. Novel HTO layers capped by Se6+ cations in KGa3(SeO4)(2)(OH)(6) led us to synthesize other alkali metal gallium selenates, NaGa3(SeO4)(2)(OH)(6) and RbGa3(SeO4)(2)(OH)(6), using hydrothermal reactions. Thermal analyses, infrared spectroscopy, elemental analyses, and dipole moment calculations for the reported materials are also presented.