A novel NbO-type framework constructed from Dawson-like tungstobismuthate and copper complex fragments

Abstract

A rare organic–inorganic hybrid compound based on the Dawson-like tungstobismuthate, [H₂bipy][Cu(bipy)(H₂O)₂][Cu(bipy)₃][H₃BiW₁₈O₆₀]·H₂O (bipy: 4,4′-bipyridine) (1a) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, cyclic voltammetry (CV) and powder XRD. Single-crystal X-ray analysis reveals that in 1a each tungstobismuthate fragment [H₃BiW₁₈O₆₀]⁶⁻ (BiW₁₈) acts as a tetradentate ligand connecting four cationic chains of four Cu-bipy complexes via the terminal oxygen atoms to form a three-dimensional (3D) structure with NbO-type topology. The electrochemical behaviours of 1a were investigated in 0.5 M Na₂SO₄ + H₂SO₄ (pH 2.5) solutions by CV. In the potential range between −0.65 and 0.4 V, the compound 1a exhibits the successive redox processes of W and Cu. The electrocatalytic experiments indicate that the compound 1a has good electrocatalytic activities towards the reduction of NO₂⁻ and H₂O₂.