COLUMNAR LIQUID-CRYSTALS IN OLIGOSACCHARIDE DERIVATIVES .2. 2 TYPES OF DISCOTIC COLUMNAR LIQUID-CRYSTALLINE PHASE OF CELLOBIOSE ALKANOATES

A series of cellobiose octaalkanoates, Cel-II-n (n is the carbon number of the alkyl chain), with n = 7-14 were prepared and their mesogenic properties examined by differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction. All of these compounds form enantiotropic discotic columnar phases, in which the columns are built up by a regular stacking of the cellobiose moieties and are packed in a two dimensional lattice. Homologues with n = 9-14 form the D(ho) phase only whilst the compound with n = 7 forms the D(ro) phase. The n = 8 compound forms the D(ho) phase at higher temperatures and the D(ro) phase at lower temperatures. Structural parameters obtained from X-ray diffraction studies are presented for both phases.