Carbohydrate liquid crystals: Synthesis and characterisation of the methyl-6-O-(n-acyl)-α-d-glucopyranosides

• Published in: Chemistry and physics of lipids Vol. 164; no. 2; pp. 118 - 124
• Main Authors: Cook, Andrew G., Wardell, James L., Imrie, Corrie T.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.02.2011
• Subjects: Glucosides - chemical synthesis; Glucosides - chemistry; Hydrogen Bonding; Liquid crystals; Liquid Crystals - chemistry; Molecular Weight; Smectic A phase; Spectroscopy, Fourier Transform Infrared; Transition Temperature; Variable temperature FTIR; Smectic A phase; Liquid crystals; Hydrogen bonding; Variable temperature FTIR
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/j.chemphyslip.2010.11.007

Seven members of the methyl-6-O-(n-acyl)-α-d-glucopyranosides have been synthesised and their transitional properties determined. The undecanoyl and octadecanoyl members do not exhibit liquid crystallinity while the members having chain lengths between dodecanoyl and hexadecanoyl exhibit a monotropic smectic A phase. Variable temperature infrared spectroscopy reveals that the hydrogen bonding within the system shows a marked change at the melting point but apparently no change at the smectic A-isotropic transition. This observation is interpreted in terms of Goodby's model for the smectic A phase in which the carbohydrate moieties are located at the centre of the smectic bilayer and assuming that hydrogen bonded aggregates persist into the isotropic phase. Within this framework, the unusually low values of the entropy change associated with the smectic A-isotropic transition may also be accounted for.