Ionic liquid crystals of imidazolium salts with a pendant hydroxyl group

Abstract

A 2-hydroxyl pendant group was anchored on the N-alkyl chain of imidazolium ionic liquid crystals. This hydroxyl group enhanced the hydrogen bonding interactions between neighboring compounds and, therefore, widened the temperature range of the mesophase, as compared to those without the hydroxyl group. Many room temperature ionic liquid crystals were formed. Polarized optical microscopy, differential scanning calorimetry, X-ray diffraction and infrared spectroscopy were used to study the properties of these materials. The molecular structure of one of the compounds was determined by single crystal X-ray diffraction, in order to have a better understanding of the structure relation between the solid and liquid crystal.