Inorganic‐Organic Hybrid Crystals Derived from Polyoxovanadate and Ionic‐Liquid toward Promising Conductive Materials

Abstract

Conductive polyoxovanadate inorganic‐organic hybrid crystals comprising alkaline earth metal (divalent) cations were successfully obtained with the use of an ionic‐liquid cation having imidazolium and methacryloyl moieties (denoted as MAImC1). Two types of crystals containing decavanadate ([V10O28]6‒, V10) anion were obtained as [MAImC1]2Ca2[V10O28]·16H2O·2C2H5OH (MAImC1‐Ca‐V10) and [MAImC1]2Mg2[V10O28]·18H2O·2C2H5OH (MAImC1‐Mg‐V10). Connection modes of the divalent cations were different: Ca2+ cations were connected to V10 to form a {[Ca(H2O)5]2V10O28]}2‒ anion in MAImC1‐Ca‐V10, while a discrete [V10O28]6‒ and hydrated [Mg(H2O)6]2+ were present in MAImC1‐Mg‐V10. Conductivities under a fully humidified condition at 353 K (80 °C) were high values of 3.0 × 10–4 S cm–1 for MAImC1‐Ca‐V10 and 3.3 × 10–3 S cm–1 for MAImC1‐Mg‐V10, respectively. The higher conductivity under hydrated conditions suggests proton as a conductive carrier. The better conductivity of MAImC1‐Mg‐V10 is plausibly derived from the more effective hydrogen‐bonded network in the crystal lattice.