One-dimensional imidazole aggregate in aluminium porous coordination polymers with high proton conductivity

Abstract

The development of anhydrous proton-conductive materials operating at temperatures above 80 °C is a challenge that needs to be met for practical applications. Herein, we propose the new idea of encapsulation of a proton-carrier molecule—imidazole in this work—in aluminium porous coordination polymers for the creation of a hybridized proton conductor under anhydrous conditions. Tuning of the host–guest interaction can generate a good proton-conducting path at temperatures above 100 °C. The dynamics of the adsorbed imidazole strongly affect the conductivity determined by 2H solid-state NMR. Isotope measurements of conductivity using imidazole-d4 showed that the proton-hopping mechanism was dominant for the conducting path. This work suggests that the combination of guest molecules and a variety of microporous frameworks would afford highly mobile proton carriers in solids and gives an idea for designing a new type of proton conductor, particularly for high-temperature and anhydrous conditions.