Dicationic imidazolium-based ionic liquids and ionic liquid crystals with variously positioned fluoro substituents

A series of new dicationic imidazolium-based organic salts bearing fluoro substituents on the bent-core unit and/or linker benzene-ring positions has been synthesized and characterized. The properties of these salts, including transition and decomposition temperatures, and density were determined, indicating that their performance is strongly dependent on the positions of the fluoro substituents, the number of carbon atoms in the alkyl group, and the anion present. Examination by polarized optical microscopy showed that the four salts (compounds 4c, 7a, 7b and 8b, where the alkyl group was C12H25-) were mesomorphic and these data were supported by DSC measurements.