Order Parameters for Isomeric Phenyl Substituted Anthraquinone Dyes Dissolved in Nematic Liquid Crystals Mixtures-Influence of the Host

Abstract

Substitution of the anthraquinone ring system has provided dyes suitable for guest-host applications. In general, one seeks to elongate the anthraquinonic system through a fourth ring. Different molecular structures have been proposed which all have similar ordering in the liquid crystalline host. Surprisingly, the 2-p-alkoxyphenyl substituted 1,5-dihydroxy-4, 8-diaminoanthraquinones have a higher order parameter in liquid crystalline mixtures of positive dielectric anisotropy made from cyano substituted molecules. They lose this property in a system consisting of molecules without cyano groups at the terminii of the molecular axes.

The properties of two isomeric substituted anthraquinone dyes in different hosts are compared in order to illustrate the considerable influence that dye-liquid crystal interactions may have on dye order parameter.