Two proton-conductive hybrids based on 2-(3-pyridyl)benzimidazole molecules and Keggin-type heteropolyacids

•2-(3-Pyridyl)benzimidazole could form hydrogen bonds via the N–H groups.•Heteropolyacids have suitable characteristics to be used excellent proton conductors.•Two proton-conductive hybrids based on Keggin HPAs and 3-PyBim were constructed.•The structures were determined by using single-crystal X-ray diffraction data.•They showed good proton conductivities of 10−3 S cm−1 at 100 °C under 35–98% RH.

Two proton-conductive organic/inorganic complexes were constructed by Keggin-type heteropolyacids and 2-(3-pyridyl)benzimidazole molecules. Single-crystal X-ray diffraction analyses revealed that two complexes crystallized in the monoclinic space group P21/c, exhibited different unit cell parameters, and presented different hydrogen-bonded networks constructed by 2-(3-pyridyl)benzimidazole molecules, [PMo12O40]3− anions and solvent molecules. The results of thermogravimetric analyses suggest that two supramolecular complexes have different thermal stability based on the different hydrogen-bonded networks. Two complexes at 100 °C under 35–98% relative humidity showed a good proton conductivity of about 10−3 S cm−1. The proton conductivities of two complexes under 98% relative humidity both increase on a logarithmic scale with temperature range from 25 to 100 °C. At 100 °C, both complexes showed poor proton conductivities of 10−8–10−9 S cm−1 under acetonitrile or methanol vapor.

Graphical abstractTwo molecular hybrids constructed by Keggin-type heteropolyacids and 2-(3-pyridyl)benzimidazole molecules showed good proton conductivities of 10−3 S cm−1 at 100 °C under 35–98% relative humidity.Figure optionsDownload full-size imageDownload as PowerPoint slide