Synthesis and liquid crystalline studies of disc-shaped molecule on azo-bridged benzothiazole-phenyl ethers

Abstract

A new series of triphenylene core attached by six peripheral arms containing benzothiazole-azo with terminal ethoxy unit have successfully been synthesized and their liquid crystalline properties were characterized. The members in this series differ by the length of the methylene unit of-(CH2)(n)-, where n, varied following ascending order from 5 to 10. The molecular structure was characterized by elemental (C, H and N) analysis and spectroscopic methods including Fourier Transform Infrared (FT-IR) and Proton Nuclear Magnetic Resonance (H-1 NMR). The texture and the phase transition temperatures were investigated by using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The disc-shape molecule with shorter spacer (n = 5) showed monotropic nematic phase. The higher homologues with n = 8-10 exhibited enantiotropic nematic phase and monotropic smectic C phase. The XRD diffraction studies further confirm the presence of smectic C without any discotic columnar phase. (C) 2016 Published by Elsevier B.V.