Discotic columnar liquid crystals in oligosaccharide derivatives III. Anomeric effects on the thermo-mesomorphic properties of cellobiose octa-alkanoates

The α-and β-anomers of cellobiose octa-alkanoates with purities higher than about 95 per cent were prepared from β -cellobiose by two simple esterification methods. The carbon number n of the acyl substituents ranged from 7 to 10 in both anomers. Both α -and β -anomers exhibited two types of discotic columnar phases (Dho and Dro), depending on n and temperature, but their phase diagrams were appreciably different. Generally, the α -anomers formed more stable mesophases than the β -anomers. In the D_ro phase of the β -anomers, the column axis was tilted from the normal to the ‘disks’, while no such tilting was observed in the other phases.