Ionic liquid crystals derived from dl-Phenylalanine: Mesomorphism, optical behavior and evaluation of toxicological profile

Abstract

Methane sulfonate and p-toluene sulfonate (4-methyl benzene sulfonate) salts of esters of racemic 2-Amino-3-phenylpropanoic acid (dl-Phenylalanine) and fatty alcohols were synthesized in good yields and investigated for their liquid crystalline properties using Polarizing Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC). Six out of seven derivatives were found to be liquid crystalline from the first series while four out of twelve derivatives were found to be ionic liquid crystals from the second series. The refractive indices of one of the ionic liquid crystals were measured at variable wavelengths and temperatures and found to exhibit a high Abbe number and low dispersive power. For evaluation of the toxicological profile, binding interactions of hsDNA with one of the derivatives from each series were recorded under physiological conditions. The experimental studies by UV–Visible and Fluorescence spectroscopy suggested a weak interaction between the ionic liquid crystals and hsDNA and, that too, mainly through minor grooves. As the strength of binding seems to be weak, a safe nature of the reported ionic liquid crystals could be expected.