PROCEEDINGS ARTICLE | October 15, 2004
Proc. SPIE. 5518, Liquid Crystals VIII
KEYWORDS: Diffraction, Scattering, Molecules, X-rays, X-ray diffraction, Chromium, Solids, Liquid crystals, Temperature metrology, Liquids
An optically active liquid crystal compound, bis-[4’-(1-methylheptyloxy-carbonyl)-4-biphenyl] terephthalate, possessing two chiral centers at both peripheral ends was prepared, and the liquid-crystalline properties investigated. This compound showed a liquid crystal phase with a 3D superstructure of the defects, i.e., the smectic Q (SmQ) phase, between the antiferroelectric and isotropic liquid phases. Complicated x-ray diffraction spots appeared in the small angle region in the SmQ phase due to the formation of the 3D network of the defects, however, only broad scattering was observed in the wide angle region. Reducing the number of phenyl rings of this compound decreased the stability of the SmQ phase, thus the resulting compound just exhibited the antiferroelectric phase. Even in the isotropic phase above the SmQ or antiferroelectric phase of these compounds, a clear x-ray diffraction scattering was detected in the small angle region, suggesting a possible molecular pre-organization in the isotropic phase. Contact studies showed that another liquid crystal superstructure, i.e., a twist grain boundary phase, was induced by mixing these chiral compounds or by mixing the antiferroelectric compound with an achiral compound. Helical structures induced in the nematic phase were also examined for these and the related chiral compounds.
