DSC and POM Study of New Thermotropic Unsymmetrical Azomethines Derived from 4-Octadecyloxybenzaldehyde

Abstract

New thermotropic liquid crystals containing long octadecyloxy chain, one mesogen (Schiff base) and different functional end-groups such as biphenyl-4-carbonitrile, ethylcarbazole, 4-phenoxy, or 4-(heptadecafluoroctyl) were synthesized via an one-step route. Transition temperatures and phase characterization were studied by differential scanning calorimetry (DSC) and polarizing optical microscope (POM) techniques. The amine had an effect on the mesomorphic properties of the azomethines. As a result of DSC and POM investigations it was shown that liquid-crystalline properties of the azomethines exhibit a strong dependence of the end-groups. Based on the POM and DSC measurements the following mesophases were detected: smectic A, smectic B, and smectic G. In this article, we will present characterization of the liquid-crystalline azomethines of great interest for the emerging field of molecular electronics.

Keywords:

• Azomethines
• mesomorphic properties
• Schiff bases
• smectic mesophases
• thermotropic properties

Acknowledgments

The authors thank Dr. Patrice Rannou from CEA Grenoble (France) for POM measurements of compound A1.