N-ACYL-BETA-D-GLYCOPYRANOSYLAMINES CONTAINING 1,4-DISUBSTITUTED CYCLOHEXYL AND PHENYL RINGS - MESOMORPHISM AND MOLECULAR-STRUCTURE RELATIONSHIPS

A variety of N-acyl-beta-D-glycopyranosylamines incorporating aliphati c and/or aromatic groups has been prepared regiospecifically and in go od yield in a one step reaction of the required acid chloride with com mercially available D-glycosylamines. The dependence of mesophase beha viour on the degree and nature of intermolecular hydrogen bonding, as well as the size and nature of the hydrophilic and hydrophobic parts o f the core and the linking groups between the two have been studied. O f the compounds investigated only the N-(4-alkoxybenzoyl)-beta-D-gluco pyranosylamines and pentylcyclohexylacetyl)-beta-D-glucopyranosylamine exhibited an observable thermotropic liquid crystal phase. The compou nds synthesized were essentially insoluble in water and no lyotropic m esomorphism was observed. It is clear that it is the number of groups on the hydrophilic carbohydrate part of the molecule capable of hydrog en bonding, after a crucial length of the hydrophobic part of the mole cule has been attained, that primarily determines thermotropic mesopha se behaviour. However, it has also been found that an odd number of un its in the central linkage between the hydrophilic and lipophilic part s of the molecule leads to significantly higher transition temperature s than those of compounds incorporating linkages with an even number o f units. X-Ray diffraction studies imply that there is no intercalatio n of the hydrophobic parts of the molecule in the crystalline state. H owever, some intercalation is thought to occur after melting to form t he bilayer structure of the smectic A phase.