Hydrogen-bonded ionic liquid crystals: pyridinylmethylimidazolium as a versatile building block

Utilizing hydrogen bonding between pyridine and benzoic acids, hydrogen-bonded ionic liquid crystals were prepared from pyridinylmethylimidazolium and alkoxy-substituted benzoic acids. Depending on the number of alkoxy substituents, smectic C (SmC), rectangular columnar (Colr), and cubic (Cub) phases were obtained from mono-, di-, and tri-substituted benzoic acids, respectively. These phases were investigated with X-ray diffraction, differential scanning calorimeter, and polarized optical microscopy.