Synthesis and mesomorphic behaviour of high polarisability materials for non-linear optical applications

Abstract

A variety of high polarisability materials have been synthesised with thioester and alkyne linking groups, and isothiocyanato and cyano terminal groups. The synthesis of these materials is presented and the transition temperatures and optical parameters of the materials are discussed and compared to those of the parent ester and non-linked analogues. The thioester and isothiocyanate units provide very high polarisabilities although the isothiocyanato unit leads to reduced mesophase thermal stabilities when compared to analogous cyano-terminated mesogens.

Keywords:

• high polarisability
• isothiocyanate
• thioester
• thiophene

Acknowledgements

The work reported here was funded by the Defence Research Agency (Malvern) and is published by permission of the director, HMSO. We wish to express our thanks to Mrs. B. Worthington, Mr. R. Knight and Mr. A.D. Roberts for spectroscopic measurements. © British Crown Copyright 2012/DRA. Published with the permission of the controller of Her Britannic Majesty's stationary office.