Controllable\nSynthesis and Ultrahigh Proton Conduction\nof a Hydrogen-Bond Network

The functionalization of polyoxometalates with organic\nligands\nprovides a new-style strategy to accurately incorporate polyoxometalates\nwith advanced functional organic moieties on their surfaces, the development\nof which has attracted increasing research interest due to the potential\napplications. A germanium tungstate Na<sub>2</sub>(H<sub>3</sub>O)<sub>6</sub>[{Ru<sup>IV</sup>(bpy)}<sub>2</sub>{WO<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)}<sub>2</sub>(GeW<sub>11</sub>O<sub>39</sub>)<sub>2</sub>]·27H<sub>2</sub>O (bpy = 2,2′-bipyridine) with two ligands\ncovalently modified was triumphantly synthesized, using the conventional\none-pot hydrothermal method. It was systematically characterized by\nthermogravimetric analysis (TGA), elemental analysis, infrared (IR)\nspectroscopy, single-crystal X-ray diffraction, X-ray photoelectron\nspectroscopy (XPS), powder diffraction (PXRD), scanning electronic\nmicroscopy (SEM), and ultraviolet–visible (UV–vis) spectroscopy.\nThe two-dimensional (2D) layered structure was established through\nhydrogen bonding and Na<sup>+</sup> bridges. Impedance measurements\nindicate that it displays outstanding proton conduction properties,\nwith a splendid conductivity up to 1.24 × 10<sup>–2</sup> S·cm<sup>–1</sup> under 353 K and 90% relative humidity\n(RH), owing to the rich interlayer hydrogen-bond network formed by\nthe organic ligands ({RuC<sub>10</sub>H<sub>8</sub>N<sub>2</sub>}<sup>4+</sup> and {WC<sub>2</sub>O<sub>4</sub>}<sup>4+</sup>), hydrated\nprotons (H<sub>3</sub>O<sup>+</sup>), and crystal waters.