Synthesis and mesomorphism of related series of triphilic ionic liquid crystals based on 1,2,4-triazolium cations

The synthesis, liquid crystal and conductivity properties of a series of 27 salts based on the 5-(4-(alkyloxy)phenyl)-1,2,4-triazol-4-ium cation bearing a perfluoroalkyl chain with triflate, tetrafluoroborate and bistriflimide anion are reported. The cations are regarded as triphilic on account of their three distinct regions – hydrocarbon, fluorocarbon and ionic. The mesophases were characterised by a combination of polarised optical microscopy, calorimetry and small-angle scattering experiments using both X-rays and neutrons, while thermal stability was probed using thermogravimetric analysis. The liquid crystal properties are found to be dependent on the anion and the length of the perfluorocarbon chain, which effects combine to determine aspects of the self-organisation in the mesophases. A strong dependence of conductivity on the anion is seen, which is in turn related to its charge density.