A crystalline imidazole-carboxylic acid-based hydrogen-bonded organic framework with high proton conductivity

Abstract

A hydrogen-bonded organic framework (HOF-SZU-1) was successfully synthesized from an organic linker containing both imidazole and carboxylic acid groups and structurally characterized. The ordered hydrogen bond networks formed by imidazolium, carboxylic acid, and carboxylate groups were favorable to construct continuous proton-conductive pathways in the crystal structure. Therefore, at 100 °C and 98 % relative humidity, HOF-SZU-1 manifested a prominent proton conductivity of up to 4.0 × 10⁻³ S cm⁻¹. It was also worth noting that HOF-SZU-1 exhibited excellent water/acid/alkali resistance, and structural integrity after the electrochemical test, indicating its extraordinary structural and chemical stability. Finally, the proton conduction process in the framework of the HOF was studied minutely.