Phase transition behaviours of calamitic liquid crystals comprising phenylbenzothiazole core

Abstract

A series of new calamitic liquid crystals 2-[4-(4-alkyloxybenzoyloxy)-phenyl]benzothiazoles comprising a benzothiazole core, terminal alkyl chain and an ester linkage were synthesised and characterised. This series consists of 13 members, wherein the members differ by the length of alkyloxy chain (C _n H_2n+1O⁻, where n = 2–10, 12, 14, 16, 18). Their mesomorphic properties were studied by using differential scanning calorimetry, optical polarising microscopy and powder X-ray diffraction techniques. Enantiotropic nematic phase was present throughout the series, i.e. from the lowest member (n = 2) until the highest member (n = 18) of the series. The smectic A phase emerged from the nonyloxy derivative onwards.

Keywords:

• phenylbenzothiazole
• nematic
• smectic A
• enantiotropic

Acknowledgements

The authors would like to thank Universiti Tunku Abdul Rahman for the financial supports and research facilities. The powder XRD measurements are supported by beamline BL17A (charged by Dr Jey-Jau Lee) of the National Synchrotron Radiation Research Center, Taiwan.