Chiral ionic liquid crystals with a bulky rigid core from renewable camphorsulfonic acid

Abstract

Renewable chiral bulky rigid D- and L-camphorsulfonic acids were introduced as new building blocks in the design of ionic liquid crystals with long chain alkylamines (C_nH_2n+1NH₂; n = 12, 14, 16 and 18) by the direct reaction of acid and amine. The phase transition behaviors of the obtained salts were investigated using DSC, POM, FTIR, XRD and CD spectroscopy, respectively. The salts with shorter alkyl chain lengths exhibited lower liquid crystal transition temperatures and wider mesophase ranges. The vibration of the N–H bonds was weakened or even disappeared with increasing temperature, which was probably due to the decrease in the change of dipole moment of the liquid crystals.