Switchable dielectric constant in an inclusion compound bis(thiourea) imidazolium chloride

Abstract

Inclusion compounds that contain dynamic polar guests possess rich electrical properties such as ferroelectricity and switchable dielectric constant upon undergoing order–disorder-type phase transitions. We here report a thiourea-based inclusion compound (Him)[(TU)₂Cl] (Him = imidazolium, TU = thiourea) that undergoes two reversible structural phase transitions at 139 K and 145 K, which are induced by the order–disorder transformations of the Him cation guests in the channels formed by the anionic [(TU)₂Cl] components. Switching of the dielectric constant is thus triggered between the low- and high-dielectric states.