Ketones-Nematogens with Moderate Negative Dielectric Anisotropy and High Clearing Points

Abstract

Anisotropic ketones whose rigid cores contain phenyl and cyclohexyl units were synthesized. The carbonyl group was incorporated either in the terminal substituents or in the link between the core units. The mesmorphic behaviour of these ketones is described and correlated with their chemical structure. The l-(4-alkanoylphenyl)-4-trans-alkylcyclohexanes as well as the l-(4-alkanoylphenyl)-4-(rani-alkan-oylcyclohexanes show nematic phases. In contrast to laterally substituted compounds, these ketones have clearing points which are higher than those of the corresponding hydrocarbons. Another advantage of these nematogens is the ease of synthesis.