Azomesogens with polar chloro, nitro and phenolic –OH substituents

Abstract

Two new mesogenic homologous series containing chloro, nitro and phenolic hydroxy groups were synthesised and their molecular structures characterised by a combination of element analysis and standard spectroscopic methods. The mesomorphic behaviour of the compounds of both series was investigated by polarising optical microscopy and, in some cases, differential scanning calorimetry. All the compounds of both the series exhibit an enantiotropic nematic mesophase. In series I higher members also exhibit an enantiotropic smectic A (SmA) mesophase, whereas in series II the enantiotropic SmA mesophase commences somewhat earlier for the middle members. The mesomorphic properties of both series are compared with each other and also with the properties of other structurally related series to evaluate the effects of different polar substituents on mesomorphism.

†. This paper was presented at the International Conference on Liquid Crystals (ICLC‐2006) held at Department of Physics, University of Mumbai, Santacruz (E), Vidyanagari, Mumbai during 5–8 December 2006.

Keywords:

• azomesogen
• polar substituent
• smectic A phase

Acknowledgements

The authors are thankful to the dean, Faculty of Technology and Engineering, and head, Applied Chemistry Department, for providing the research facilities. One of us (A. K. P.) is grateful to the University Grants Commission, New Delhi, India for the award of UGC Major Research Project {F. 30‐68/2004(SR)} for financial support.

Notes

†. This paper was presented at the International Conference on Liquid Crystals (ICLC‐2006) held at Department of Physics, University of Mumbai, Santacruz (E), Vidyanagari, Mumbai during 5–8 December 2006.