The influence of lateral substituents on the occurrence of a transition between two polar smectic phases with antiferroelectric properties

Abstract

The synthesis and mesomorphic properties of two homologous series of bent-core (BC) compounds derived from 2,7-dihydroxynaphthalene are reported. The two series differ from one another by an electron-withdrawing or an electron-donating lateral substituent on the middle phenyl ring of the arms of the BC. Very interestingly, contrasting results are obtained in which polar phases are observed in compounds containing a chloro substituent and apolar smectic C and nematic phases are obtained when this substituent is replaced by a methyl group. The mesophases have been characterised by using a combination of polarised light optical microscopy, differential scanning calorimetry, X-ray diffraction measurements, electro-optical and dielectric studies.

Keywords:

• bent-core
• polar mesophases
• antiferroelectric
• smectic C
• nematic

Acknowledgements

The authors thank Mrs K.N. Vasudha for technical support and the NMR Research Centre, Indian Institute of Science, Bangalore, for recording the NMR spectra. They also thank Dr Arun Roy for useful discussion.

Additional information

Funding

BKS thanks the Indian National Science Academy, New Delhi, for financial support.