82598-08-1Relevant academic research and scientific papers
LIQUID CRYSTALLINE COMPOUND, LIQUID CRYSTAL COMPOSITION, AND LIQUID CRYSTAL DISPLAY ELEMENT
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Page/Page column 51, (2010/07/06)
The invention provides a liquid crystal compound having stability to heat, light and so forth, a wide temperature range of a nematic phase, a small viscosity, a suitable optical anisotropy, a suitable elastic constant K33, a suitable and negative dielectric anisotropy, and an excellent compatibility with other liquid crystal compounds. The invention provides a liquid crystal composition containing the compound described above and having stability to heat, light and so forth, a small viscosity, a suitable optical anisotropy, a suitable and negative dielectric anisotropy, a suitable elastic constant K33, a low threshold voltage, a high maximum temperature of a nematic phase, and a low minimum temperature of the nematic phase. The invention also provides a liquid crystal display device having a short response time, a small power consumption, a low driving voltage, and a large contrast, and containing the composition described above which can be used in a large temperature range. For example, a liquid crystal compound having four or more rings in which the central ring has 2,3-difluorophenoxy such as trans-4'-[2,3-difluoro-4-(trans-4-propylcyclohexyl)phenoxymethyl]-trans-4-pentylbicyclohexyl is provided. Further provided is a liquid crystal composition containing the compound, and a liquid crystal display device using this liquid crystal composition.
The Synthesis and Liquid Crystal Behavior of p-Benzotrifluoride Compounds III
Liang, J. C.,Cross, J. O.,Chen, L.
, p. 199 - 206 (2007/10/02)
Two compounds with the general structure R-CY-CY-CH2-CH2-Ph-CF3 were synthesized where CY is a 1,4-disubstituted trans cyclohexyl ring, and R is a n-alkyl group.The synthesis procedure is discussed and structural assignments confirmed by proton and carbon 13 NMR spectroscopy.Liquid crystal behavior was evaluated by DTA and polarized microscope.We discovered that the two compounds have smectic and nematic phases and can be used in fast switching liquid crystal mixtures.
Substituted Terminal Alkyl Groups and Their Prospects in Liquid Crystal Chemistry
Osman, Maged A.
, p. 353 - 360 (2007/10/02)
Polar substituents may be attached to the terminal alkyl groups of rodlike mesogens to increase their ε and to give a positive or negative Δε.The mesomorphic behaviour of some biphenyls, phenylcyclohexanes and bicyclohexanes with substituted alkyl groups was studied and compared to that of the corresponding unsubstituted compounds.In the first series no conclusive results could be obtained due to the relatively high melting points and low clearing points of the investigated compounds.In the phenylcyclohexanes and bicyclohexanes, substituents in ω-position were found to enhance the clearing temperature.In contrast, cyano groups in α-position depressed the clearing point.However, this depression is still much less than that caused by the introduction of lateral substituents in the phenyl moieties of the rigid core.
Aliphatic Liquid Crystals with Positive Dielectric Anisotropy
Osman, Maged A.,Huynh-Ba, T.
, p. 959 - 963 (2007/10/02)
Cyanoethyl-substituted cyclohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthesized.Their mesomorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohexanoates show mesomorphic properties in contrast to the corresponding cyano derivatives.Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of its mesophase.In aromatic compounds, the cyanoethyl group leads to lower clearing points.These phenomena are attributed to the influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.
