Synthesis, thermal and optical behaviour of non-symmetric liquid crystal dimers α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-[pentyl-4-(4′-phenyl)benzoateoxy]hexane

Abstract

A series of six non-symmetric liquid crystal dimers α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-[pentyl-4-(4′-phenyl)benzoateoxy]hexane have been synthesized and characterized. These dimers vary from one another in terms of the terminal substituent (H, CH₃, C₂H₅, F, Cl and Br) with different polarizabilities and molecular sizes. Investigation on the thermal behaviour shows that the dimer with a more polarizable terminal substituent of Br atom exhibits a smectic A phase as well as an enantiotropic nematic phase. Influence of the molecular size of the terminal substituent in stabilizing the liquid crystalline properties is also studied.

Keywords:

• non-symmetric
• dimer
• terminal substituent
• polarizability
• molecular size

Acknowledgements

The authors would like to thank the Ministry of Science, Technology and Innovation (MOSTI), Malaysia, and Universiti Sains Malaysia for the eScience grant no. 03-01-05-SF0366 (305/PKIMIA/613328) and Research University grant no. 1001/PKIMIA/811127.