EFFECT OF CHLORO AND NITRO TERMINAL SUBSTITUENTS ON MESOMORPHIC PROPERTIES OF AZOBENZENE LIQUID CRYSTALS
Journal: Acta Chemica Malaysia (ACMY)
Author: Kamruzzaman, Roushown Ali and Tariqul Hasan
This is an open access journal distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Substitutent on the mesogen plays a crucial role in determining the shape and mesogenic properties of liquid crystals. In order to evaluate the influence of terminal chloro and nitro substitutions on the structural shape and mesogenic properties, two azobenzene 1-(4-X-phenyl)-2-(4-(hexayloxy)phenyl)diazene (X is Cl or NO2) liquid crystals have been synthesized by diazotization followed by etherification with hexyl bromide. The structural characterizations of the compound have been performed by spectroscopic methods and studied the mesogenic property by differential scanning calorimetry (DSC) and polarizing optical microscope (POM). Rod-shaped liquid crystals and mesophase formation were obtained by the terminal chloro and nitro substituents of the azobenzene. The textures obtained with polarizing optical microscope (POM) analysis showed enantiotropic smectic A (SmA) mesophase for chloro and nematic mesophase for nitro substituted azobenzene. Differential scanning calorimetry confirmed two Cr-SmA and SmA-I phase transitions both on heating and cooling.