A Dawson-type {P4W24} modified using phenylphosphonic acid with excellent proton conductivity

Abstract

A case of organic–inorganic hybridized phosphotungstate modified using aromatic organophosphonic acid, K₄Na₄H₁₁[KCo₂(H₂O)₁₀P₄W₂₄O₉₂{(PhPO)₂}]·48H₂O (1), was successfully synthesized in conventional aqueous solution. The prominent structural feature is that the total structure of [KP₄W₂₄O₉₂{(PhPO)₂}]²³⁻ resembles a V-shaped structure, which was stabilized by two [Co(H₂O)₅]²⁺ ions. Furthermore, it can be connected into a three-dimensional mesh structure using K⁺ ions. Surprisingly, 1 possesses a remarkably high proton conductivity of 1.59 × 10⁻² S cm⁻¹ at 95% RH and 318 K probably due to the fact that its structure contains large amounts of lattice water molecules, coordination water molecules and counter cations.