Beilstein J. Org. Chem.2009,5, No. 73, doi:10.3762/bjoc.5.73
connected via alkyloxy spacers, was efficiently prepared by a two-step procedure. Phaseengineering results in an optimum of the mesophase range and low melting temperature when the nematogens are desymmetrised with a butoxy and a heptyloxy spacer. The mesophases are enantiotropic and over the whole
, indicating the alignment of two molecular axes along individual directors in the magnetic field. These observations may be rationalised with larger assemblies of V-shaped molecules isotropically distributed around the direction of the magnetic field.
Keywords: biaxial nematics; liquid crystals; phase
engineering; thiadiazoles; V-shaped mesogens; Introduction
Most molecules forming nematic liquid crystals, the nematogens, are based on rod-shaped (calamitic), anisometric cores with peripheral flexible chains along the molecular long axis [1]. Nematic phases are the simplest liquid crystalline mesophases
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Graphical Abstract
Figure 1:
Uniaxial nematic (left) and biaxial nematic (right) phases and their corresponding indicatrices.
Beilstein J. Org. Chem.2009,5, No. 48, doi:10.3762/bjoc.5.48
smectic phases, nematic phaseengineering by using V-shaped molecules, saddle-shaped columnar systems displaying anomalous odd-even effects, theoretical studies on the origin of chirality transfer in liquid crystalline host-guest systems, liquid crystalline carboranes and dyes and discotic phenanthrene