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Novel liquid crystalline cuneane-caged derivatives. Structure property relationship study

Gyula Benyei ,István Jalsovszky ,Aniko Vajda ²,Antal Jákli ³,Dietrich Demus ⁴,Shankar Rao ⁵,Krishna Prasad ⁵,Katalin Fodor-Csorba ²
Gedeon Richter Ltd. H-1475, Budapest, 10. P.O. Box 27, Hungary Department of Organic Chemistry, Eötvös Loránd University, H-1117 Budapest, Pázmány Péter sétány 1/A., Hungary ²Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, H-1525 Budapest, P.O.Box 49, Hungary ³Liquid Crystal Institute, Kent State University, Kent, OH44242, USA ⁴International Scientific Consulting Office, Veilchenweg 22, 06118 Halle, Germany ⁵Centre for Liquid Crystal Research, Jalahalli, Bangalore 560 013, India
The synthesis and phase behavior of the first cuneane derivatives with liquid crystalline properties are reported. This new class of liquid crystalline materials is the homologous series of bis[4-(n-alkoxyphenyl)]cuneane-2,6-dicarboxylates. They were synthesized by two different methods: either by isomerization of the formerly prepared bis[4-(n-alkoxyphenyl)]cubane-1,4-dicarboxylates or by direct esterification of the cuneane-2,6-dicarboxylic acid. Enantiotropic nematic phases were observable for the first four homologues, whereas the higher homologues exhibited enantiotropic smectic A phase. The bis[4-(n-octylphenyl]cuneane-2,6-dicarboxylate exhibited the SmA phase at lower temperature, than its octyloxy analogue. The mesophases were investigated and established by polarization optical microscopy, differential scanning calorimetry and X-ray diffraction methods. Quantum chemical calculations suggest an elongated structure of these new liquid crystalline compounds.

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