Novel supramolecular hydrogen-bonded cholesteric mesogens: liquid crystalline, thermoptical and glass-forming properties

Abstract

Liquid crystalline, thermoptical and glass-forming properties of a series of novel supramolecular hydrogen bonded cholesteric mesogens have been described. These assemblies were built via intermolecular hydrogen bonding between cholesteric esters containing pyridine groups and cholesterol containing carboxylic acid moieties. All hydrogen-bonded complexes exhibit well defined cholesteric phases over a range of temperatures depending upon the number of carbon atoms present in their alkyl chains. The formation of pure LC materials on 1 ∶ 1 complexation could be confirmed from the phase diagrams of the binary mixtures and infrared absorption spectra. By rapid cooling of the hydrogen bonded assemblies from their cholesteric temperature to 0 °C glassy liquid crystalline films maintaining helical molecular order were obtained. Different reflection colors of the cholesteric phase were selectively and repeatedly fixed by changing the starting temperature of rapid cooling.