Carbazole nematic liquid crystals

Abstract

A number of calamitic 2,7-diary-N-alkyl-substituted carbazoles with an enantiotropic nematic phase have been prepared. Branching of the aliphatic chain attached to the nitrogen atom in the carbazole ring leads to significantly lower liquid crystal transition temperatures. These new materials show a lower ionisation potential than fluorene analogues and blue photoluminescence in solution and as thin solid films.

Keywords:

• carbazoles
• nematics
• organic semiconductors

Acknowledgements

We thank the EPSRC for the award of a postdoctoral fellowship to Dr S.P. Kitney and visiting studentship support for Dr Pan Wei, the University of Hull and the China Scholarship Council for a studentship to Weixiao Bao, the Saudi Arabian Government for the award of a PhD studentship to Mr M.S. Al-Kalifah and the Spanish Government for a postdoctoral fellowship to Dr M. Haro. We express our thanks to Dr R. Lewis (¹H NMR) and Dr K. Welham (MS) for spectroscopic measurements and Mrs K. Kennedy for combustion analyses.