Unsymmetrical tetracatenar liquid crystals containing 2-phenylbenzoxazole: Synthesis and characterisation

Abstract

A series of 2-phenylbenzoxazole derivatives containing an intramolecular hydrogen-bonded Schiff's base linkage have been synthesised. All are liquid crystalline, displaying only the smectic phase transition, apart from one compound which seems to be non-mesogenic. These compounds may be the first examples reported of tetracatenar liquid crystals containing the 2-phenylbenzoxazole moiety. The optical properties of the target compounds were evaluated in solution.

Keywords:

• Benzoxazole
• gallic acid
• tetracatenar
• intramolecular H-bonding
• Schiff's base
• Smectic phase

Acknowledgements

We thank CSIR (New Delhi) for financial assistance. K.C.M. is grateful to UGC (New Delhi) for an UGC–Emeritus fellowship, and T.G. to CSIR (New Delhi) for a research fellowship. We also wish to thank DST (New Delhi) for providing the Bruker NMR (400 MHz), a Perkin–Elmer CHN Analyzer and FTIR and UV–Vis spectrometers.