Synthesis and mesomorphic study of new phenylthiophene liquid crystals

Abstract

New homologous series of phenylthiophene-based liquid crystalline compounds, namely (E)-4-(((5-phenylthiophene-2-yl)methylene)imino)phenyl 4-alkoxy benzoate (Tn), bearing Schiff base/ester spacers, have been synthesised and characterised. The molecular structures of the newly prepared compounds were confirmed by elemental analyses, Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Thermal and mesomorphic behaviours of all derivatives were investigated via polarising optical microscopy (POM) and differential scanning calorimetry (DSC). Independent of the terminal alkoxy-chain length, the prepared homologues were found to display the nematic (N) phase enantiotropically with a wide temperature range, with properties covering all investigated terminal alkoxy chain lengths. The phase behaviours of present series were compared with those of previously investigated mesogens based on the thiophene moiety only.