Spectroscopic characterization of mesogen order in discotic liquid crystal

Abstract

Infrared and Raman spectra of the discotic liquid crystal molecules benzene–hexa-hexanoate (BH6), benzene–hexa-heptanoate (BH7), benzene–hexa-octanoate (BH8), and benzene–hexa-nananoate (BH9), and of mixtures of BH7 with BH8, are reported as a function of temperature. The 1615 cm−1 infrared band is strong in the Raman spectrum of BH7 and is taken as a characteristic of and diagnostic for central core disorder in all these molecules and mixtures. The aliphatic side chains are shown to disorder at much lower temperatures than the central core, and order in the central core is shown to remain throughout the liquid crystalline region.