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

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 MAImC 1 ). Two types of crystals containing decavanadate ([V 10 O 28 ] 6− , V 10 ) anion were obtained as [MAImC 1 ] 2 Ca 2 [V 10 O 28 ] ⋅ 16H 2 O ⋅ 2 C 2 H 5 OH (MAImC 1 −Ca−V 10 ) and [MAImC 1 ] 2 Mg 2 [V 10 O 28 ] ⋅ 18H 2 O ⋅ 2 C 2 H 5 OH (MAImC 1 −Mg−V 10 ). Connection modes of the divalent cations were different: Ca 2+ cations were connected to V 10 to form a {[Ca(H 2 O) 5 ] 2 V 10 O 28 ]} 2− anion in MAImC 1 −Ca−V 10 , while a discrete [V 10 O 28 ] 6− and hydrated [Mg(H 2 O) 6 ] 2+ were present in MAImC 1 −Mg−V 10 . Conductivities under a fully humidified condition at 353 K (80 °C) were high values of 3.0×10 −4 S cm −1 for MAImC 1 −Ca−V 10 and 3.3×10 −3 S cm −1 for MAImC 1 −Mg−V 10 , respectively. The higher conductivity under hydrated conditions suggests proton as a conductive carrier. The better conductivity of MAImC 1 −Mg−V 10 is plausibly derived from the more effective hydrogen‐bonded network in the crystal lattice.