77017-57-3Relevant academic research and scientific papers
ORDER PARAMETERS FOR ISOMERIC PHENYL SUBSTITUTED ANTHRAQUINONE DYES DISSOLVED IN NEMATIC LIQUID CRYSTALS MIXTURES - INFLUENCE OF THE HOST.
Cognard,Hieu Phan,Basturk
, p. 327 - 340 (2007/10/02)
Substitution of the anthraquinone ring system provided dyes suitable for guest-host applications. In general, one seeks to elongate the anthraquinonic system through a fourth ring. Different molecular structures have been proposed which all have similar ordering in the liquid crystalline host. Surprisingly, the 2-p-alkoxyphenyl substituted 1,5 dihydroxy-4, 8-diaminoanthraquinones have a higher order parameter in liquid crystalline mixtures of positive dielectric anisotropy made from cyano substituted moelcules. They lose this property in a system consisting of molecules without cyano groups at the terminii of the molecular axes. The properties of two isomeric substituted anthraquinone dyes in different hosts are compared in order to illustrate the considerable influence that dye-liquid crystal interactions may have on dye order parameter.
Colorants Anthraquinoniques Stables de Parametre D'Ordre Eleve en Solution Dans les Cristaux Liquides
Cognard, J.,Phan, T. Hieu
, p. 1 - 20 (2007/10/02)
Anthraquinone dyes have been shown to be usable as "Guest" Dyes in dichroic Guest-Host displays.Whereas 1-5-N-alkyl substitution produces solutions of negative order parameter, 1- and 1-5-alkylanilino substitution give blue and violet dyes of acceptable order parameter, although admittedly too low for most industrial applications.Substitution of an anthraquinone in the 2- or 2,6-positions results in stable dyes of high order parameter in liquid crystal mixtures of positive dielectric anisotropy.The colour of the dye depends on the substituents present in the 1-, 4-, 5-, 8-positions as indicated in Table II.Substitution by an alkoxy, alkylthio or phenoxy group gives dyes of acceptable order parameter.The order parameter is greatly increased if the 2 substituting group is an alkoxyphenyl group.The highest order parameter is obtained through simultaneous p-alkoxyphenyl 2,6-substitution.These compounds give order parameters comparable with azo dyes with increased stability, provided that a mobile hydrogen is present on the 1- and/or 5-position.The presence of the dye in a L.C. mixture increases its photochemical stability.Solubility is of the order of 7percent, which allows fabrication of displays of high contrast.The order parameter increases with the alkoxy chain length and with the Host nematic transition temperature, except for mixtures containing esters.This shows the importance of dye-L.C. interactions.
