Covalent Functionalization of Dawson-Type Polyoxometalates to Achieve a Zero to Three-Dimensional Transition for Enhanced Proton Conductivity

Abstract Precise control over the dimensional organization of molecular metal oxides remains an ongoing challenge in materials design. Herein, we report a “molecular editing” strategy for Dawson-type phosphotungstate (PW) clusters through systematic ligand engineering. By progressively increasing the complexity of polydentate arylphosphonic (Apa) ligands, we guide the structural evolution from zero dimensional (0D) molecular entities to three dimensional (3D) covalent cluster networks (CCNs). The resulting 3D CCN, PW-Apa(3), achieves ultrahigh proton conductivity (1.87 × 10–2 S cm–1, 303 K, 90% RH), surpassing its 0D counterparts by a factor of 20. Mechanistic investigations indicate that this enhanced performance can be attributed to optimized proton coupled electron transfer (PCET), enabled by a synergistic interplay between structural dimensionality and electronic modulation. PW-Apa(3) exhibits exceptional proton-conducting properties, enabling its integration into an ionic skin sensor capable of multimodal detection of mechanical deformation and humidity fluctuations. This advancement paves the way for a multifunctional ionic skin platform that mimics biological sensing.