Effects of terminal substituents on mesomorphic properties of Schiff base – ester mesogens and DFT calculations

Abstract

ABSTRACT Two new groups of rod-like molecules with benzothiazole-aromatic systems: one group (B1Y) and the other (B2Z) having a Schiff and ester linkages with different terminal groups were synthesised. The structures of synthesised compounds were confirmed by using physicochemical techniques such as 1H-NMR, mass spectra and FT-IR spectra. Differential scanning calorimeter (DSC) and polarising optical microscopy have been employed to verify their liquid crystalline behaviours and transition temperatures. All the synthesised compounds (groups B1Y and B2Z) showed enantiotropic nematic phase except the compound B2 H. The thermal range of nematic phase for the compounds was greatly affected by the type of terminal groups. The change of the type of terminal groups in the compounds (B2Z) was theoretically studied to investigate if the theoretical calculations possess an agreement with the practical results.