Amphitropic liquid-crystalline properties of some novel alkyl furanosides

Monoalkyl substitution in carbohydrate systems is known to affect the melting behaviour of sugars and support the introduction of thermotropic liquid-crystalline phases. Similarly, the inclusion of a relatively long aliphatic chain in the molecular structure affects the formation of lyotropic liquid crystal phases. In some instances, long-chain-substituted carbohydrates can generate both lyotropic and thermotropic phases, and hence these materials have been described as amphitropic. Here, the thermotropic and lyotropic liquid-crystalline properties of an amphitropic family of monoalkylated furanosides are described, in addition, the thermal behaviour of the materials is discussed in terms of simple molecular models of geometrically optimised structures, and the resulting degree of hydrogen bonding possible for the various materials.