DE3115147A1 - Dyes for liquid-crystal mixtures - Google Patents

Abstract

The invention relates to the use of dyes of the formula I <IMAGE> in which R is a heterocyclic radical, X is hydrogen, nitro or optionally substituted amino, hydroxyl or mercapto, and Y is hydrogen, nitro or optionally substituted amino, hydroxyl or mercapto, where the ring A may also be substituted, and where Y is not NH2 if X is not hydrogen, in electro-optical displays containing liquid crystals, and to liquid-crystal mixtures containing dyes of the formula in Claim 1.

Description

'' Colorants for liquid crystal mixtures

The invention relates to the use of dyes of the general formula I. in which R is a heterocyclic radical, X is hydrogen, nitro or optionally substituted amino, hydroxy or mercapto and Y is hydrogen, nitro or optionally substituted amino, hydroxy or mercapto, where ring A can still be substituted, where X is not hydrogen and Y is not SH2 is in electro-optical displays containing liquid crystals.

heterocyclic radicals R are, in particular, optionally substituted and / or fused rings, 5- or 6-ring heterocycles of the oxazole, oxdiazole, thiazole, thiadiazole, imidazole or triazole series. The radicals R correspond in detail, for example, to the formulas in which R1 is hydrogen, optionally substituted alkyl, cycloalkyl or aryl, optionally substituted alkyl or cycloalkyl-mercapto, R2 is hydrogen, optionally substituted alkyl, cycloalkyl or aryl, R3 is hydrogen, optionally substituted alkyl, cycloalkyl or phenyl or carbon ester, R4 is hydrogen , optionally substituted alkyl, cycloalkyl or phenyl or carbon ester, R3 and R4 together are an optionally substituted fused benzene ring, R5 is hydrogen or optionally substituted alkyl, cycloalkyl or phenyl and ZO, S or NH.

R1 radicals are, for example, C1- to C12-alkyl, through hydroxy, C1- Substituted to C 8 -alkoxy or phenyl, optionally interrupted by oxygen C2 to C8 alkyl, C5 to C7 cycloalkyl, optionally by C1 to C8 alkyl, C1- to C8-alkoxy, phenoxy, phenoxyalkyl, C1- to C8-alkanoyloxy, benzoyloxy, phenylalkyl, Phenyl, diphenyl, cyclohexyl or chlorine substituted phenyl, optionally by Oxygen and / or sulfur-interrupted C1 to C8 alkyl mercapto, C5 to C7 cycloalkyl mercapto or by optionally interrupted by oxygen and / or sulfur C1- to C8-alkyl, C1- to C8-alkoxy, phenoxy, phenoxyalkyl, C1- to C8-alkanoyloxy, Benzoyloxy, phenylalkyl, phenyl, diphenyl, cyclohexyl, carbon ester or chlorine substituted Aralkyl mercapto.

Individual radicals R1 are z. E.g .: methyl, ethyl, butyl, methoxymethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, cyclohexyl, 2-cyclohexoxyethyl, phenoxymethyl, 2-phenoxyethyl, 2-phenylethyl, phenyl, 4-methylphenyl, diphenyl, 4-cyclohexylphenyl, Methylthio, ethylthio, butylthio, n-octylthio, cyclohexylthio, 2-methoxyethylthio, Phenylmethylthio, 2-phenylethylthio, 2-phenoxyethylthio, 4-cyanophenyl-methylthio, 4-phenoxyphenyl-methylthio, 4-phenylmethoxy-phenylmethylthio or 4- (2-phenylethyl) -phenylmethylthio, 4-acetoxyphenyl-methylthio, 4-butyryloxyphenylmethylthio, 4-capronyloxyphenyl-methylthio, 4-benzoyloxyphenyl-methylthio.

The radicals for R2 are the same in the context of the general definition as to be mentioned for R1.

R3 and R4 radicals are, for example, C1 to C4 alkyl, if appropriate substituted by C1- to C4-alkyl, chlorine or bromine.

Phenyl, C5 to C7 cycloalkyl or C1 to C8 alkoxycarbonyl.

Individual radicals R3 and R4 are z. B. (same or different) methyl, Ethyl, phenyl, p-chlorophenyl, ethoxycarbonyl, butoxycarbonyl or cyclohexyl.

Fused-on benz rings (for R3 and R4 together) can, for example be substituted by methyl, ethyl, methoxy, ethoxy, butoxy or chlorine.

For R5 are e.g. B. in addition to hydrogen methyl1 ethyl, butyl, phenyl, Mention should be made of 4-ethylphenyl, 4-butylphenyl.

X radicals are, for example, hydrogen, amino, methylamino, butylamino, Octylamino, phenylmethylamino, phenylamino, 4-ethylphenylamino, 4-butylphenylamino, 4-chlorophenylamino, hydroxy, ethoxy, butoxy, phenoxy, 4-ethylphenoxy, mercapto, Ethylthio, phenylthio or nitro.

The radicals for Y are the same in the context of the general definition as to name for X.

The ring A can, for example, also be replaced by chlorine, bromine, hydroxy, mercapto, Amino or a radical R may be substituted.

According to the invention, compounds of the formula I are preferably used, in which X or Y are hydrogen, hydroxy, mercapto or amino and R is an oxdiazolyl or thiadiazolyl radical.

Preferred substituents for these radicals are, for. B.

R1: propyl, butyl, hexyl, phenyl, 4-diphenyl, 2-methoxyethylthio, 2-butoxyethylthio, butylthio, phenoxymethyl, 2-phenoxyethyl, phenylmethylthio, 4-butyryloxyphenylmethylthio, 4-benzoyloxyphenyl-methylthio, 4-phenoxyphenylmethylthio, 4-phenylmethoxy-phenylmethylthio, 4-diphenylmethylthio or cyclohexylthio.

R2: propyl, butyl, hexyl, phenylmethyl, phenyl, 4-diphenyl, phenoxymethyl, 2-phenoxyethyl or 2-methoxyethyl.

The symmetrical (1, 3, 4) oxdiazolyl and Thiadiazolyl radicals.

Liquid crystal mixtures and their use are z. B.

already from the German Offenlegungsschrift 29 02 177, 29 03 095 and 29 50 944 known. Further literature can be found in these laid-open documents and discussed the theoretical basis of the use according to the invention.

Compared to those previously proposed for the use according to the invention Compounds, the compounds of the formula I are distinguished by a particularly high level dichroic ratio, good lightfastness and good solubility in liquid crystalline Media out. They can still be easily obtained in pure form.

The dyes can be prepared by known processes.

The measurements were made in the nematic phase by Merck ZLJ-1691 carried out.

Examples 1 - 8 are the following anthraquinone dyes: 'E.g. colour o NH2NN 1 03 yiÜ0i``CH2-O 4 red red o NH2N-N 2 <S-CH2 4 red 0 O NH3, N, N 3 S-CH 2 O-CH2 red 0 O OH NN 4 w S S-CH2 4 yellow 0 O OH o 5 <° S-CH20-C11-C3H7 violet 0) 12 0 5 NN OSN ~ N 6 <S k S-CH 4 yellow O Example about color 7 H21 <CH2 o blue H2N O O NH, NN 8 <a S-C4H9 blue H2N O The measurements were made on a spectrophotometer from

Hewlett-Packard 8540. The dichroic ratio CR was determined by measuring the extinctions E parallel (E ") and E perpendicular (E) after the The relationship E "CR = E # was determined. For this purpose, commercially available measuring cells with a Layer thickness of 10 pm used.

The degree of order S was determined according to the well-known equation CR-1 S = CR + 2 calculated.

In the drawing, the absorption spectra are in parallel and perpendicular polarized light for compound 2.

The table shows the dichroic ratio for dyes 1 to 8 and the degree of order compiled.

Table of dye CR S 1 9.8 0.75 2 11.5 0.78 3 11.0 0.77 4 7.5 0.68 5 11.1 0.77 6 10.0 0.75 7 8.8 0.72 8 11.7 0.78 drawing Blank page

Claims (2)

Claims 1. Use of dyes of the general formula I in which R is a heterocyclic radical, X is hydrogen, nitro or optionally substituted amino 'hydroxy or mercapto and Y is hydrogen, nitro or optionally substituted amino, hydroxy or mercapto, where ring A can still be substituted, where X is not hydrogen and Y is not Is NH2, in electro-optical displays containing liquid crystals. 2. Liquid-crystal mixtures containing dyes according to the general Formula in claim 1.