Design, Synthesis and Analysis of Chlorohydroquinone Derivatives—Liquid Crystalline Complexes

Abstract

A novel linear double hydrogen-bonded liquid crystalline material is designed and isolated. The ingredients of the mesogens synthesized are chloro hydroquinone (ClHQ) and p-n alkyloxy benzoic acid (nBAO) where n varied from pentyl to dodecyl alkyloxy carbon numbers. The series is abbreviated as ClHQ + nBAO, and seven of eight synthesized complexes are found to exhibit liquid crystalline phases. These liquid crystalline complexes are characterized by Fourier Transformation Infrared spectroscopy (FTIR) in order to confirm the formation of hydrogen bond. Mesophases and their corresponding transition temperatures are studied by polarizing optical microscopy (POM) and their respective enthalpy values along with the order of the transitions are determined by Differential Scanning Calorimetry (DSC). The experimental measurement of tilt angle is carried out by optical extinction method and fitted to the theoretically predicted mean field exponent which is found to be in good agreement. Dielectric relaxations at different temperatures in nematic phase for the complexes have been carried out and their corresponding activation energy values are calculated from Cole–Davidson plots. Light filtering action in the liquid crystalline complexes is done to validate the commercial applications of these mesogens.

Keywords:

• Benzoic acid
• dielectric relaxations
• DSC
• hydrogen bond
• liquid crystals

Acknowledgments

The divine and graceful blessings of almighty Bannari Amman, the infrastructural support rendered by Bannari Amman Institute of Technology, and the financial support rendered by the Board of Research in Nuclear Sciences (BRNS) of Department of Atomic Energy (DAE), India (Sanction No. 2012/34/35/BRNS), are gratefully acknowledged by the authors.