THERMOTROPIC LIQUID-CRYSTALLINE GLUCOSE DERIVATIVES WITH MESOGENIC SIDE-CHAINS

Many glucose derivatives have been studied so far for their liquid cry stalline behavior. Penta-O-n-alkanoylglucopyranoses have been reported to form discotic columnar mesophases. Thermotropic liquid crystals of glucose with mesogenic side chains, consisting of a mesogen, an alkyl spacer and a tail, form the subject of this study. The glucose deriva tives were prepared by complete esterification of the hydroxyl groups of glucose with the mesogenic side chains. Their characterization was based on the analysis from cross polarizing microscopy, differential t hermal calorimetery, wide-angle X-ray diffraction pattern and nuclear magnetic resonance (both C-13 and H-1) spectra. Smectic and chiral nem atic (cholesteric) phases have been observed in these macromolecules. The effect on the phase behavior of varying the tail length in the sid e chains of the molecule was studied. The structural arrangement of su ch molecules has been proposed based on the observations. These are re ported here as the first such observations of liquid crystalline phase s in completely substituted chiral glucose molecules with mesogenic si de chains.