Mesomorphic studies of novel azomesogens having a benzothiazole core: Synthesis and characterisation

Abstract

Novel liquid crystals, including 2-[4-(4 ′ -n-alkoxybenzoyloxy)phenylazo]-6-fluorobenzothiazoles (Series E) and 2-[4-(4 ′ -n-alkoxybenzoyloxy)naphtha-1-ylazo]-6-fluorobenzothiazoles (Series F), have been synthesised and characterised. Each series contains 13 homologous members differing by the length of the alkoxy chain. In series E the derivative with C₁ to C₇ chain length were found to exhibit enantiotropic smectic C (SmC) and nematic (N) mesophases. The C₈ homologue possessed enantiotropic SmC, smectic A (SmA) and N mesophases, while the longer chain homologues (C₁₀ to C₁₄) showed enantiotropic SmC and SmA mesophases. The C₁₆ and C₁₈ homologues possessed only SmA mesophases. In Series F all the compounds (C₁ to C₁₈) exhibited only the enantiotropic nematic mesophase.

Keywords:

• 6-fluorobenzothiazole
• azomesogens
• SmA
• nematic
• enantiotropic

Acknowledgments

We are grateful to Gujarat Narmada Valley Fertilizer Company Ltd, Bharuch, for providing facilities for the elemental analyses, to Atul Industries Ltd, Atul, for DSC analyses, and to SAIF Chandigarh for FT–IR, ¹H–NMR, ¹³C–NMR and mass spectral analyses. We also wish to thank Professor D.W. Bruce, University of York, UK, for providing literature.

Notes

This paper was initially presented at the 18th Indian Liquid Crystal Conference, held at the Department of Physics, NERIST, Itanagar, India, 15–17 November, 2011