N-Methylimidazolium containing metal phosphate–oxalates: solvent-free synthesis, crystal structure, and proton conduction

Abstract

Two N-methylimidazolium containing metal phosphate–oxalates (denoted SCU-40 and SCU-42) were prepared under solvent-free conditions. SCU-40 has a three-dimensional structure with a zeolitic crb topology, while SCU-42 has a layered structure with an sql net. Notably, SCU-42 shows a proton conductivity of 4.2 × 10⁻³ S cm⁻¹ at 85 °C under 95% relative humidity, which is the highest among all crystalline metal phosphate–oxalates so far.