Influence of linkage and terminal group on the liquid crystalline and helical twisting behaviours of cholesteryl esters

Abstract

Three series of cholesteryl esters with different linkages and terminal groups have been synthesised and characterised. All the esters except cholesteryl 6-bromohexanoate can exhibit thermotropic liquid crystalline phases in certain temperature regions. The insertion of a 4-phenoxyl and a 4-biphenylyloxy group in the ester can increase the molecular length, broaden the whole mesophase width and heighten the clearing temperature. The increasing molecular length can enforce the layered arrangement in series A and B (resulting in a monolayer smectic A phase), while destroying the layer stacking in series C (resulting in a suppressed or absent interdigitated smectic A phase). Meanwhile, the molecular structure played an important role in the molar helical twisting power and its temperature dependence.

Keywords:

• cholesteryl ester
• phase behaviour
• helical twisting power
• temperature dependence

Acknowledgements

This work was supported by the National Natural Science Fund for Distinguished Young Scholar (Grant No. 51025313), National Natural Science Foundation (Grant No. 50973010), Science and Technology Project of Beijing, China (Grant No. D090803044209001), Research Fund of State Key Laboratory for Advanced Metals and Materials and Open Research Fund of State Key Laboratory of Bioelectronics (Southeast University).