14978-35-9Relevant academic research and scientific papers
Liquid Crystalline Properties of Cholesteryl ω-Arylalkanoates
Koden, Mitsuhiro,Miyake, Shiro,Takenaka, Shunsuke,Kusabayashi, Shigekazu
, p. 2387 - 2390 (2007/10/02)
The thermal properties of the homologous series of cholesteryl ω-(4-benzoylphenyl)- (I), ω-(4-benzylphenyl)- (II), ω-benzoyl- (III), and ω-phenoxyalkanoate (IV) have been investigated.For series I and II the cholesteric-isotropic (Ch-I) transition temperatures, enthalpies, and entropies show a remarkable alternation.For series III and IV, the transition temperatures, enthalpies, and entropies exhibit weak alternation and their trends are opposite to those for series I and II, and the cholesteryl ω-phenylalkanoates.The cholesteric-isotropic transition temperatures are discussed in terms of the geometrical and electrical alternations stemming from the terminal aryl groups, and also the relative importance between these two terms.
Synthesis, Structure, and Excimer Formation of Aromatic Cholesteric Liquid Crystals
Sisido, Masahiko,Takeuchi, Kazuhiko,Imanishi, Yukio
, p. 2893 - 2898 (2007/10/02)
Cholesteryl ο-arylalkanoates having phenyl, 1-naphthyl, and 1-pyrenyl groups as aromatic groups were synthesized, and some of those were found to form the cholesteric liquid crystal (CLC) phase.The pitch and the screw sense of the helix were determined from the selective reflection wavelength and the circular dichroism.The pitch was around 800 nm for cholesteryl 5-(1-naphthyl)pentanoate and about 970 nm for cholesteryl 3-(1-naphthyl)propionate.The helix sense was left-handed for all cholesteryl esters which form the CLC phase.The orientation of naphthyl groups within each quasi-nematic layer was qualitatively discussed from the sign of cirular dichroism at the 1La absorption band.The short axis of the 1-naphthyl group was parallel to the optical or the molecular axis of the quasi-nematic layer in the CLC of cholesteryl 1-naphthylpropionate and -pentanoate, whereas the short axis of 2-naphthyl group was perpendicular to the optical axis of the CLC of cholesteryl 2-naphthylpropionate.The orientation of the excimer transition moment was investigated by circularly polarized fluorescence spectroscopy.The transition moments for all chromophoric CLC's were found to be nearly perpendicular to the optical axis.From these spectroscopic data, an intralayer excimer configuration for 1- and 2-naphthyl groups was proposed.In the mixture of cholesteryl 3-(1-pyrenyl)propionate (60 molpercent) and 3-phenylpropionate (40 mol percent), the excimer formation was more efficient in the CLC phase than in the crystalline phase.
