Synthesis and thermotropic behaviour of imidazole-terminated liquid crystals

Abstract

Two novel liquid crystals containing terminal imidazole groups (Imi-COOH and Imi-DAH) were designed and synthesised. Imi-COOH exhibits a high-temperature monotropic smectic mesophase that is substantially stabilised by hydrogen bonding between acid and imidazole end-groups. Despite its rigid diacylhydrazine core, which offers the capability of forming lateral hydrogen bonds, Imi-DAH exhibits a nematic mesophase. Fourier transform infrared analysis suggested that the terminal imidazole group interferes with lateral hydrogen bonding between diacylhydrazine cores and destabilises the smectic mesophase. Future studies will examine how proton transport is affected by anisotropic mesophases.

Keywords:

• thermotropic liquid crystals
• imidazole
• hydrogen bonding
• smectic
• proton exchange membranes
• diacylhydrazines

Acknowledgements

The authors acknowledge the Royal Thai Government and the University of Rochester's Department of Chemical Engineering for support of this research.