Purely inorganic frameworks based on polyoxometalate clusters with abundant phosphate groups: single-crystal to single-crystal structural transformation and remarkable proton conduction

A pure-inorganic framework based on {P 4 Mo V 4 Mo VI 2 } clusters with rich phosphate groups has been synthesized. It underwent a single crystal to single crystal conversion in air to form a new framework with changes both in the metal valent state and coordination environment. The new framework exhibits an ultra-high proton conductivity of 1.33 × 10 −2 S cm −1 at 95 °C and 98% relative humidity and excellent stability. A pure-inorganic framework 1 underwent a SCSC transformation to form a new framework 1′ , which has high proton conductivity.