THERMOTROPIC LIQUID-CRYSTALS BASED ON OLIGOSACCHARIDES - N-ALKYL-1-O-BETA-D-CELLOBIOSIDES

n-Alkyl 1-O-beta-D-cellobiosides with an alkyl length ranging from 7 to 18 in carbon number m were synthesized, and their thermal properties were studied in comparison with those of the already-known monosaccharide homologues, n-alkyl 1-O-beta-D-glucopyranosides. The cellobiosides were found to exhibit a thermotropic mesophase at higher temperatures than the glucopyranosides. Depending on m and thermal history, the cellobiosides showed various textures such as homeotropic, transient batonnets, polygonal, and fan-shaped textures. Like in the case of the monosaccharide homologues, the difficulty of aligning the samples prohibited a full classification of the mesophase, but the X-ray diffractograms of the unaligned cellobiosides indicated that their mesophase belongs to smectic A(or less possibly, smectic C). The m dependence of the lamella thickness was much weaker than (about half) that of the monosaccharide homologues. Possible molecular arrangements of the cellobiosides in the mesophase were presented.