Liquid crystal molecules with an enyne rigid core
Armand Soldera
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Abstract
New mesogens are always a source of interest, especially when they possess a non-conventional architecture. In this article are presented the synthesis and polymorphism of a series of compounds possessing a 1,4-diaryl-1-buten-3-yne moiety as the rigid core with an alkoxy chain on each side. Such a core is termed an enyne core. The alkoxy chain is lengthened on each side of the enyne core according to two different fashions: symmetrically and asymmetrically. In this way a rich polymorphism is achieved in some compounds. At lower chain length, the compounds exhibit smectic H and nematic phases where cybotactic groups are observed in X-ray diffraction patterns. As the alkoxy chains extend, smectic C and smectic F phases appear. The non-cylindrical shape of these compounds involves a molecular packing that is preserved throughout the polymorphism. A comparison between symmetric and asymmetric compounds, from X-ray diffraction pattern analysis of their smectic H phases, reveals a parallel molecular stacking. It also discloses the importance of the moiety that is lengthened since different polymorphisms are obtained.
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https://www.ijert.org/study-of-novel-liquid-crystalline-materials-with-lateral-ester-group https://www.ijert.org/research/study-of-novel-liquid-crystalline-materials-with-lateral-ester-group-IJERTV4IS090565.pdf Novel twelve homologues having azolinkage of series 4-Methyl-[3'-carbethoxy-4' (4"-n-alkoxy benzoyloxy)] azobenzenes have been synthesized.The first member of the series is nonmesogenic. The ethyl to n-dodecyl homologues exhibit enantiotropic nematic mesophases. The n-tetradecyloxy and n-hexadecyloxy homologue exhibit monotropic smectic mesophases. The plot of transition temperatures versus number of carbon atoms in alkoxy chain shows usual falling tendency for the nematic-isotropic transition temperatures. The mesogenic behaviour of present series is explained by comparing its homologue with other homologue of related mesogenic series..The synthesised compounds are characterised by combination of elemental analysis and standard spectroscopic methods. For the exhibition of mesomorphic property the role of ester and azo linkages has been discussed. The impact of lateral carbethoxy group on mesomorphism is also discussed.
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