JPS62101657A - Anthraquinone compound and liquid crystal composition - Google Patents

Abstract

NEW MATERIAL:Anthraquinone compounds of formula I (wherein R<1> is H, an alkyl, an alkoxy, hydroxy, halogen, or ester group; R<2> is a substd. phenyl, naphthyl, or heterocyclic ring which may be substituted). USE:The compds. exhibit a high dichroic ratio, good solubility and good color display, when used in liquid crystal compsn. Nematic liquid crystals for use in the liquid crystal compsn. can be widely chosen, so long as they exhibit a nematic state over a working temperature range. PREPARATION:A compd. of formula II is reacted with a compd. of HS-R<2> to obtain the desired compd. The reaction is carried out in a solvent such as sulfolane or an amide solvent in the presence of an acid acceptor at a temp. of 50-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel anthraquinone compound and a liquid crystal composition containing the compound.

(Prior art) Conventionally, a liquid crystal composition made by dissolving a dye compound in liquid crystal is interposed between two opposing electrodes, and color display is performed by utilizing the guest-host effect between the dye compound and the liquid crystal. is known. As this pigment compound, for example, yellow to
It is also known that anthraquinone compounds exhibiting a yellow-orange hue are used in liquid crystal compositions (Japanese Unexamined Patent Application Publication No. 1983-1999).
73067, JP-A-57-158262)
.

By the way, a preferable dye compound used in such a liquid crystal composition needs to have properties such as particularly high dichroic ratio and high solubility in liquid crystal.

(Problems to be Solved by the Invention) However, according to studies by the present inventors, conventionally known anthraquinone compounds are particularly required as preferred dye compounds used in liquid crystal compositions. SUMMARY OF THE INVENTION The present invention aims to provide a novel anthraquinone compound capable of solving the above-mentioned conventional problems and a liquid crystal composition containing the compound.

(Means for Solving the Problems) As a result of further studies to achieve the above object, the present inventors found that one of the anthraquinone nuclei of anthraquinone dyes
A liquid crystal composition that exhibits a high dichroic ratio and good solubility in liquid crystals by introducing a heterocyclic thio group or a naphthylthio group at the position or 5-position, and can also provide good color display by using such a compound. The present invention was achieved based on the knowledge that the following can be obtained. That is, the present invention provides general formula CI
) (wherein, R1 is a hydrogen atom, an alkyl group, an alkoxy group,
It represents a hydroxy group, a halogen atom, or a carboxylic acid ester group, and R2 represents a phenyl group having a substituent, a naphthyl group, or a heterocyclic group which may have a substituent. ) and a liquid crystal composition characterized by containing the compound.

Next, the structure of the anthraquinone compound of the present invention represented by the general formula CI) will be explained in detail.

In the general formula (1), R1 is a hydrogen facet, an alkyl group,
It represents an alkoxy group, a hydroxy group, a halogen atom, or a carboxylic acid ester group, and R2 represents a phenyl group having a substituent, a naphthyl group, or a heterocyclic group such as a pyridyl group or a pyrimidyl group which may have a substituent. . The substituents to be substituted on the phenyl group include an alkyl group; an alkoxy group; a halogen atom; a group represented by -0+CH2CH2OsuR3 (m is an integer of 1 to 5, and R3 is an alkyl group); + CH=CH→lower-COOR' (n is O
or 1 and R4 is an alkyl group, -←CH2CH20-
Indicates a group represented by +FFV-R3, an aryl group, a cycloalkyl group, or a trans-4-alkylcyclohexyl group. ), an aryl group, a cycloalkyl group, a trans-4-alkylcyclohexyl group, and the like. Examples of the substituent to be substituted on the naphthyl group include an alkyl group, an alkoxy group, a hydroxy group, a halogen atom, or a carboxylic acid ester group, and examples of the substituent to be substituted on the above heterocyclic group include an alkyl group, an alkoxy group, and the like. etc.

The alkyl group that is a substituent for R1, R3, R4, phenyl group, naphthyl group, and heterocyclic group has 1 carbon number.
-18 etc., and may have a substituent such as a carboxylic acid ester group. R1 above,
Examples of the alkoxy group that is a substituent for a phenyl group, a naphthyl group, and a heterocyclic group include alkoxy groups having 1 to 18 carbon atoms. Examples of the halogen atom as a substituent for R1, the phenyl group and the naphthyl group above include F.

Examples include elementary atoms, chlorine atoms, bromine atoms, and the like.

Examples of the carboxylic acid ester group which is a substituent for R1 and the naphthyl group mentioned above include a carboxylic acid methyl ester group and a carboxylic acid ethyl ester group. Further, the aryl group represented by R above includes a 4-alkyl (for example, furkyl having 1 to 13 carbon atoms) phenyl group, 4-alkoxy (for example, alkoxy having 1 to 13 carbon atoms) phenyl group, piphenyl group, Examples include cyclohexylphenyl group, trans-4-alkyl (for example, alkyl having 1 to 13 carbon atoms) cyclohexylphenyl group, and examples of the cycloalkyl group include /chlorohexyl group, cyclopentyl group, cycloheptyl group, etc. Examples of the trans-4-alkylcyclohexyl group include trans-4-alkyl (eg, alkyl having 1 to 13 carbon atoms) cyclohexyl group. In addition, the above-mentioned alkyl group or alkoxy group having 3 or more carbon atoms may be linear or branched.

More preferably, the alkyl group has 1 to 1 carbon atoms.
8 alkyl groups are mentioned, and examples of the alkoxy groups mentioned above include alkoxy groups having 1 to 8 carbon atoms. However, the above-mentioned aryl groups include alkyl or alkoxyphenyl groups having 1 to 8 carbon atoms, biphenyl groups, cyclohexylphenyl groups, trans-4-alkyl groups (for example, 1 to 8 carbon atoms).
Examples of the above-mentioned cycloalkyl group include a cyclohexyl group, and the above-mentioned trans-4-alkylcyclohexyl group is a trans-4-alkyl group (for example, a carbon number of 1
to 8 alkyl)cyclohexyl groups.

The anthraquinone compound represented by the general formula (1) is synthesized, for example, by the method shown in the reaction formula below.

(R1 and R2 in the above general formulas [1] to (I) have the same meaning as in the forepaw general formula [I].) That is, this reaction is performed using N,N-dimethylformamide, acetamide, N-methyl An amide solvent such as pyrrolidone or a solvent such as dimethyl sulfoxide or sulfolane is used, and an acid binder such as an alkali metal carbonate such as potassium carbonate or sodium carbonate, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, In the presence of an acetate such as potassium acetate or sodium acetate or an organic acid binder such as triethylamine, the temperature is 50°C to 200°C, preferably 80°C to 1
It can be carried out at a temperature of 50°C.

The nematic liquid crystal used in the liquid crystal composition of the present invention includes:
As long as it exhibits a nematic state within the operating temperature range, it can be selected from a fairly wide range. Further, by adding an optically active substance to be described later to such a nematic liquid crystal, it can be made to take a cholesteric state. Examples of nematic liquid crystals include the substances shown in 1 to 3 of Table 1 below, or derivatives thereof.

Table 1-1 Table 1-2 Table 1-3 In Table 1 above, R1 represents an alkyl group or an alkoxy group,
X represents an alkyl group, an alkoxy group, a nitro group, a cyano group or a norogen atom.

The liquid crystals 1 to 3 in Table 1 all have positive dielectric anisotropy, but the known ester-based, azoxy-based liquid crystals, which have negative dielectric anisotropy,
Azo-based, Schiff-based, pyrimidine-based, diester-based, or biphenyl ester-based liquid crystals can also be mixed with liquid crystals having positive dielectric anisotropy to form positive liquid crystals as a whole. Further, even a liquid crystal having negative dielectric anisotropy can be used as is if an appropriate element configuration and driving method are used.

The host liquid crystal substance used in the liquid crystal composition of the present invention includes:
Any of the liquid crystals shown in Table 1 or a mixture thereof may be used, such as the liquid crystal sold by Merck under the trade name ZLI-1132, the liquid crystal sold under the trade name ZLI-1565, or Br1tish Drug.
A liquid crystal sold by House Company under the trade name E-7 is useful.

As the optically active substance used in the liquid crystal composition of the present invention, chiral nematic compounds such as 2-methylbutyl group,
There are compounds in which optically active groups such as 3-methylbutoxy, 3-methylpentyl, 3-methylpentoxy, 4-methylhexyl, and 4-methylhexyl groups are introduced into nematic liquid crystals. In addition, alcohol derivatives such as e-menthol and d-borneol, ketone derivatives such as d-camphor and 3-methylcyclohexane, and carboxylic acid derivatives such as d-citronellaic acid and β-camphoric acid, as shown in JP-A-51-45546. , aldehyde derivatives such as d-ntronellal, d alkene derivatives such as IJ nonene, other amines, amides, di) l) optically active substances such as l) derivatives can be used.

As a device for performing liquid crystal display using the liquid crystal composition of the present invention, a known liquid crystal display device can be used. That is, generally, transparent electrodes in an arbitrary pattern are provided on two glass substrates, at least one of which is transparent, and the two glass substrates are placed parallel to each other with an appropriate spacer interposed so that the electrode surfaces face each other. A configuration of elements is used. In this case, the spacer determines the gap between the elements. From a practical standpoint, the element gear is preferably 3 to 100 .mu.m, particularly 5 to 50 .mu.m.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

In addition, to briefly explain the order parameter indicating dichroism, the order parameter S of the dye compound can be experimentally determined from the following formula.

Here, A/ and A are the absorbances of the dye for light polarized parallel and perpendicular to the alignment direction of the liquid crystal, respectively.

Specifically, the order parameter S is a value that indicates the display contrast of a guest-host type liquid crystal element, and theoretically, the closer this value approaches 1, the less residual color in the white areas, and the brighter and higher the contrast becomes. Clear display becomes possible.

Example 1 P was added to 20m6 of N-methylpyrrolidone (hereinafter abbreviated as NMP) solution in which 90TNi of potassium hydroxide was dissolved.
-t-, 270 mg of butylthiophenol and 600 μ of a compound represented by the following structural formula:
The mixture was stirred at C for 3 hours. After the temperature was lowered, the reaction solution was discharged into a 30% saline solution. The precipitated crystals were filtered and dried, and impurities were separated and purified by column chromatography using silica gel (manufactured by Wako Pure Chemical Industries, Ltd.; C-200 trade name) as a phase and chloroform as a separation solvent, resulting in the following structure: 400 nq of the compound was obtained. This compound is 2490
It exhibited a melting point of ~249.5°C.

The above-obtained anthraquinone compound (dye) of the present invention was added to the above-mentioned mixed liquid crystal ZLI-1565 (trade name of Merck & Co.), and the liquid crystal was heated to 70°C or higher to become an isotropic liquid. The above compound (dye) was dissolved by repeating the steps of stirring thoroughly and cooling the mixture.

The liquid crystal composition of the present invention prepared in this way was treated with a homogeneous alignment treatment by applying a polyamide resin on the surface in contact with the liquid crystal, applying a polyamide resin on the surface in contact with the liquid crystal, and then rubbing it.
An inter-substrate gear made of two glass substrates was encapsulated in a 10 μm element.

In the element subjected to the alignment treatment, the liquid crystal was in a homogeneous alignment state when no voltage was applied, and the dye molecules were also aligned in the same manner according to the host liquid crystal.

The absorption spectrum of the guest-host device thus prepared was measured using both light polarized parallel to the alignment direction of the liquid crystal molecules and light polarized perpendicularly to the orientation direction of the liquid crystal molecules.
The maximum absorption wavelength of the dye for each of these polarized lights was determined. In determining the absorbance of the dye, corrections were made for absorption by the host a-crystal and glass substrate and reflection loss of the element.

Still using A/ and A soil for each polarization, the above equation The value of the order parameter (I3) was calculated from.

The above results are shown in Section 1 of Table 2 below.

Example 2 Anthraquinone compounds (pigments) of the present invention having the structural formulas shown in A2 to A28 in 1 to 3 of Table 2 below were produced and isolated by a method similar to Example 1. Using each of the 27 types of dye compounds obtained, the other conditions were the same as in Example 1, and the maximum absorption wavelength (λmax) and order value were determined.
The parameter (S) was measured and calculated.

The above results are summarized in A2 to A28 of 1 to 3 of Table 2 below.

1 in Table 2 (Note 1 = -Q- indicates trans-cyclohexyl.)
Table 2 2 2 Table 2 3 (Effects of the invention) As is clear from the above results, the novel anthraquinone compound of the present invention exhibiting a yellowish hue exhibits good solubility in liquid crystals. The liquid crystal composition of the present invention obtained by dissolving it in a liquid crystal has a high dichroic ratio and its order parameter (S) value is close to 1, so it is an industrial field that enables bright color display with high contrast. It has significant and significant effects.

Claims (2)

[Claims] (1) General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼……[I] (In the formula, R^1 is a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, a halogen atom, or a carboxylic acid ester. R^2 represents a phenyl group having a substituent, a naphthyl group, or a heterocyclic group which may have a substituent. (2) General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼……[I] (In the formula, R^1 is a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, a halogen atom, or a carboxylic acid ester. 2 represents a phenyl group having a substituent, a naphthyl group, or a heterocyclic group which may have a substituent.) A liquid crystal containing an anthraquinone compound represented by Composition.