R. Pindak

Resonant x-ray scattering at the Se edge in liquid crystal free-standing films and devices

Resonant x-ray diffraction was carried out at the Seu200aK edge in thick free-standing films of a selenophene liquid crystalline material, revealing detail of the structure of the ferro-, ferri-, and antiferroelectric phases. The ferrielectric phase was shown to have a three-layer superlattice. Moreover, the structure of a lower temperature hexatic phase was established. For the antiferroelectric phase, investigations were also carried out in a planar device configuration. The device allowed resonant scattering experiments to be carried out with and without the application of an electric field and resonant data are compared with electro-optic measurements carried out on the same device.

Diastereospecific synthesis and amphiphilic properties of new alkyl β-D-fructopyranosides

In this article we describe a novel one step stereocontrolled synthesis of alkyl 1-O-β-D-fructopyranosides from totally unprotected D-fructose. In order to avoid oligomerization of D-fructose the reactions were performed in heterogeneous media. Thus, long chain alcohols, as acceptors, were treated with D-fructose in the presence of iron(III) chloride as the promoter to give the alkyl substituted products in yields of approximately 30%. The materials produced were found to self-organise and form liquid crystal mesophases. One of the thermotropic phases exhibited by this family of compounds was found to be atypical of liquid crystal modifications normally exhibited by glycolipids. The structure of this phase was investigated by a wide variety of techniques, and sufficient evidence was gained to indicate that it is novel. A variety of possible arrangements of the molecules in the self-organised state is given based on the preliminary data.