Synthesis and properties of allyloxy-based biphenyl liquid crystals with multiple lateral fluoro substituents

Abstract

Allyloxy-based biphenyl liquid crystals, composed of alkyl chain, trans-cyclohexane and biphenyl mesogenic cores, ethylene linking groups, lateral fluoro substituents and allyloxy terminal groups were prepared via a six-step reaction based on 4-alkylcyclohexanecarbonitrile. Their structures were confirmed via infrared spectrometry, mass spectra and nuclear magnetic resonance. The mesomorphic properties of the present compounds were investigated by differential scanning calorimetry and polarising optical microscopy. The compounds exhibited negative dielectric anisotropy from −3.36 to −4.29 and a broad nematic mesophase with low melting points and high clearing points. The effects of the allyloxy terminal group and the lateral fluoro substituents on the mesomorphic properties and negative dielectric anisotropies are discussed. The present allyloxy-based biphenyl liquid crystals have potential for use in liquid crystal display mixtures.

Keywords:

• liquid crystals
• allyloxy group
• multiple lateral fluoro substituents
• mesogenic core

Acknowledgements

The authors would like to thank National Science Foundation Committee of China (no. 50802058), Program for Changjiang Scholars and Innovative Research Team in University (IRT1070) and Key Technologies R&D Program of Shaanxi Province (no. 2011K07-03) for financial support of this work.