Effects of Symmetry on the Stability of Columnar Liquid Crystals

To assess the effects of molecular symmetry on the phase transitions of columnar liquid crystals, we prepared a family of 19 discotic mesogens. This series of dibenzophenazine derivatives allowed us to compare the differences in phase transitions between sixteen pairs of isomers that differed in terms of their overall symmetry. It was found that the more symmetrical isomer had a significantly higher melting temperature in all but one case, whereas symmetry appeared to have a lesser impact on clearing temperature. A similar relationship between symmetry and melting point is also observed for triphenylene-based discotic mesogens; in these systems, the clearing points show a stronger dependence on molecular symmetry.