SOME NOVEL DISACCHARIDE-DERIVED LIQUID-CRYSTALS

Some novel disaccharide-derived amphiphiles, in which the hydrophobic long chain alkyl group and an alpha-D-glucose moiety are separated by a hydrophilic five carbon spacer or a hydrophobic furan residue, were investigated as to their mesomorphic properties using DSC, thermomicro scopy and various X-ray methods. All compounds exhibit a smectic A pha se, characterized by aggregation to a bilayered S-Ad structure. The la yer thickness d, measured by X-ray, correlates with the presence of po lar and non-polar moieties, adjoining molecules interacting via hydrog en bonding. Based on the known structural concepts for sugar-derived l iquid crystals, a model is suggested to account for the observed S-Ad layer arrangement. The mesomorphic behaviour of two N-alkanoyl derivat ives of (glucosyloxymethylfuryl)methylamine, i.e. species in which sug ar and long chain fatty acid are separated by a quasi-aromatic furan r esidue, is unusual, as different X-ray methods invariably give the sam e odd d-value indicative of a smectic layer thickness of three to four molecules.