The influence of intramolecular hydrogen bonding on the order parameter and photostability properties of dichroic azo dyes in a nematic liquid crystal host

Abstract

It has been demonstrated that intramolecular hydrogen bonding in two classes of dichroic azo dyes has a generally detrimental effect on order parameter in a nematic liquid crystal host. Derivatives of 4-(N,N-diethylamino)-4′-nitroazobenzene with hydroxy groups intramolecularly hydrogen bonded to the azo group show lower order parameters in E7 nematic liquid crystal than the parent dye, but higher order parameters than corresponding methoxy dyes. 1-Arylazo-2-naphthols with a hydrogen bonding carboxamide group in position 3 exist exclusively in the hydrazone form and show even lower order parameters. Intramolecular hydrogen bonding also has a deleterious effect on photochemical stability.

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