Calorimetric Study of the Diastereomeric Interactions of Enantiomeric Iso-octyl-benzoyloxybenzoate Solutes with a Chiral Liquid Crystal
作者:
Y.K. Yarovoy,
Vibha Patel,
M.M. Labes,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1998)
卷期:
Volume 319,
issue 1
页码: 101-109
ISSN:1058-725X
年代: 1998
DOI:10.1080/10587259808045651
出版商: Taylor & Francis Group
关键词: Enantiomer;diastereomeric;liquid crystal;calorimetry;iso-octyl-benzoyloxybenzoate;enthalpy
数据来源: Taylor
摘要:
Precision differential scanning calorimetric (DSC) analysis of the effect of doping cholesteryl nonanoate with the enantiomers of 4-(4-n-hexyloxybenzoyloxy)-isooctyl benzoate (R811 and S811) has been performed. Depressions of the enthalpies of both phase transitions, from crystalline to cholesteric and from cholesteric to isotropic phases, were found to be ∼ 1.5 times greater for the samples of cholesteryl nonanoate doped with left-handed S811. Depressions of the temperatures of phase transitions are also more pronounced in the case of S811. Thus, the left-handed enantiomer S811 affects the molecular packing of cholesteryl nonanoate much more strongly than its right-handed counterpart R811. Remarkably, the difference between the enthalpy of melting of samples containing only 1 wt% of either enantiomer reaches ∼ 20% of the enthalpy of fusion of pure cholesteryl nonanoate, indicating strong diastereomeric discrimination in the system. This calorimetric manifestation of diastereomer discrimination of S811 and R811 in cholesteryl nonanoate is in agreement with earlier observed nonsymmetrical effects of these enantiomers on the pitch of cholesteric liquid crystals; that is the left-handed S811 enantiomer constricts the pitch nine times more strongly than the right-handed R811 expands the helix.
点击下载:
PDF (394KB)
返 回