Oxadiazole-based unsymmetrical chiral liquid crystal dimers: synthesis and mesomorphic properties

Abstract

The synthesis and liquid crystalline properties of novel chiral Schiff's base dimers containing the 1,3,4-oxadiazole ring are reported. The length of the terminal S-alkyl chain has been varied. All the compounds synthesised were thermally stable and exhibited enantiotropic mesomorphism, showing either SmC*–SmA–TGB–N*–BP or SmC*–SmA phase sequence.

Keywords:

• unsymmetrical dimers
• oxadiazole
• cholesterol
• BP phase
• TGB phase
• SmA phase
• SmC* phase

Acknowledgements

We thank the DST (New Delhi) for financial assistance. One of us (P.K.S) is grateful to the CSIR (New Delhi) for a Fellowship. We also thank DST (New Delhi) for providing Bruker DPX–400 NMR and Perkin–Elmer L 120–000A IR spectrometers and a Perkin–Elmer 2400 series II CHN-analyser, under the DST–FIST programme.