A proton conductive hydrogen-bonded framework incorporating 18-crown-6-ether and dicarboxy-o-terphenyl moieties

To date, proton-conducting organic crystalline materials based on crown ethers have rarely been investigated. In this work, we reveal that flexible organic 18-crown-6 derivatives with one or two 4, 40-dicarboxy-o-terphenyl (CT) groups formed four kinds of crystalline frameworks: 1CT-18C6-I (P2(1)/n), 2CT-18C6-I (P (1) over bar), 2CT-18C6-II (P (1) over bar) and 2CT-18C6-III (Cmc2(1)). Single crystal X-ray diffraction analysis clearly suggested that the water molecules were involved a hydrogen-bonded network for two frameworks. In particular, a unique one-dimensional (1D) water pathway had formed in 2CT-18C6-III and the activation energy was evaluated by Arrhenius plots to be 0.14 eV, indicating that the proton jumps from H3O+ to the neighboring H2O in the hydrogen-bonded network of 2CT-18C6-III.

Automated summary

This study discovered four kinds of crystalline frameworks formed by flexible organic 18-crown-6 derivatives with CT groups, with one of them forming a unique one-dimensional water pathway. Single crystal X-ray diffraction analysis showed that water molecules were involved in a hydrogen-bonded network for two frameworks.