A wheel-shaped Zr-substituted phosphotungstate [{Zr(C2O4)2}3 (PO4)(P6W39O150)]39− with tunable proton conduction properties

Abstract

A wheel-shaped Zr-substituted phosphotungstate, [N(CH₃)₄]₂K₁₆Na_10.5H_10.5[{Zr(C₂O₄)₂}₃(PO₄)(P₆W₃₉O₁₅₀)]·45H₂O (1), was synthesised from a hexavacant Dawson-type precursor [H₂P₂W₁₂O₄₈]¹²⁻via a conventional solution method. Compound 1 features a wheel-shaped polyanion comprising an annular [P₆W₃₉O₁₅₀]³⁶⁻ cluster supported by a turbine-shaped [{Zr(C₂O₄)₂}₃(PO₄)]³⁻ fragment, with three oxalate groups covalently anchored to W atoms. Compound 1 was systematically characterized by IR, UV, PXRD, TGA and ³¹P NMR spectra. The ³¹P NMR spectra over time were monitored to verify the stability of 1 in aqueous solution. This compound possesses remarkable proton conductive behavior with a high conductivity of 1.18 × 10⁻² S cm⁻¹ at 368 K.