Aminobenzoic Acid Covalently Modified Polyoxotungstates Based on {XW₆} Clusters with Proton Conductivity Property

Three cases of aminobenzoic acid hybrid polyoxotungstates, Na₃(H₃O)₂[(HPW₆O₂₁) (O₂CC₆H₄NH₂)₃]·7H₂O (1), K₂(H₃O)₄[(AsW₆O₂₁)(O₂CC₆H₄NH₂)₃]·4H₂O (2), and [(H₂N(CH₃)₂]₃Na₂(H₃O)[(SbW₆O₂₁) (O₂CC₆H₄NH₂)₃]·7H₂O (3), were successfully synthesized. This is the first report of the successful assembly of the hexanuclear {XW₆} (X = HP^III, As^III, or Sb^III) clusters and organic carboxylic acid (para aminobenzoic acid) ligands. All three hybrids feature a common {XW₆} unit composed of a six-membered {WO₆} octahedral ring capped by one {XO₃} trigonal pyramid. Furthermore, these hybrids possess an extensive three-dimensional network of hydrogen bonds, which not only provide high thermal stability but also contribute to excellent proton conductive performances. Simultaneously, based on the Hirshfeld partition analysis, combined with the interaction between POMs and water molecules, the proton transport mechanisms of three hybrids were highlighted.