JPH0717849B2 - Anthraquinone compound and liquid crystal composition containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel anthraquinone compound and a liquid crystal composition containing the compound.

(Prior Art) Conventionally, a liquid crystal composition in which a dye compound is dissolved in liquid crystal is interposed between two electrodes facing each other, and color display is performed by utilizing the guest-host effect of the dye compound and the liquid crystal. Is known. It is also known that an anthraquinone compound showing a blue hue, for example, is used in the liquid crystal composition as the dye compound (Japanese Patent Laid-Open No. 58954/1983).

By the way, as a preferable dye compound used in such a liquid crystal composition, it has a maximum absorption in the vicinity of 630 to 670 nm, a high dichroic ratio, a clear blue dye compound having properties such as high solubility in liquid crystal. Is useful.

However, according to the studies by the present inventors, the conventionally known anthraquinone-based compound is not necessarily satisfactory in terms of the above-mentioned properties required as a particularly preferable dye compound used in the liquid crystal composition. Not the one.

(Problems to be Solved by the Invention) An object of the present invention is 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 Problems) As a result of further studies to achieve such an object, the present inventors have found that the compound represented by the general formula [I] (In the formula, one of X and Y represents an amino group and the other represents a hydroxyl group, and R ¹ is (R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group, and n is 1
Represents an integer of ~ 4. ), R ² and R ³ are hydrogen atoms,
It represents an alkyl group that may be substituted with an alkoxy group or an alkoxy group that may be substituted with an alkoxy group, and the alkoxy group of this substituent may be substituted with an alkoxy group. The anthraquinone compound represented by) has a maximum absorption around 630 to 670 nm and exhibits a vivid blue color, and has a high dichroic ratio and good solubility in liquid crystals, and when such a compound is used, a good color is obtained. The present invention has been reached based on the finding that a liquid crystal composition capable of displaying can be obtained. That is, the gist of the present invention is an anthraquinone compound represented by the general formula [I] and a liquid crystal composition containing the compound.

In the anthraquinone compound represented by the general formula [I] of the present invention, examples of the alkyl group represented by the substituents R ⁴ and R ⁵ include an alkyl group having 1 to 5 carbon atoms, and R ² and
Examples of the alkyl group which may be substituted with an alkoxy group represented by R ³ include an alkyl group having 1 to 8 carbon atoms or an alkyl group having 1 to 4 carbon atoms substituted with an alkoxy group having 1 to 8 carbon atoms. Examples of the alkoxy group which may be substituted with an alkoxy group include an alkoxy group having 1 to 15 carbon atoms and an alkoxy group having 1 to 4 carbon atoms substituted with an alkoxy group having 1 to 8 carbon atoms. The alkoxy group of the time substituent may be substituted with an alkoxy group having 1 to 4 carbon atoms.

The anthraquinone compound represented by the general formula [I] can be produced as follows.

For example, the general formula [II] (Wherein, X, Y and R ¹ are the same as defined in the above general formula [I]) and the following general formula [III] (Wherein R ² and R ³ are the same as defined in the above general formula [I]) and a solvent is used,
In an amide solvent such as N, N-dimethylformamide, acetamide, N-methylpyrrolidone or a solvent such as dimethyl sulfoxide or sulfolane, an acid binder, for example, an alkali metal carbonate such as potassium carbonate or sodium carbonate, sodium hydroxide or water. By reacting in the presence of an alkali metal hydroxide such as potassium oxide, an acetate such as potassium acetate and sodium acetate, and the like under the temperature condition of 100 ° C to 200 ° C, preferably 140 ° C to 180 ° C, the general formula [I ] The anthraquinone type compound represented by this can be obtained. Further, this reaction proceeds more quickly when a surfactant such as a nonionic surfactant is added.

As the liquid crystal used in the liquid crystal composition of the present invention, various liquid crystals can be used. Etc.

For example, as nematic liquid crystals, 1 to 3 in Table 1 below are used.
And the derivatives thereof.

In Table 1 above, R represents an alkyl group or an alkoxy group,
X'represents an alkyl group, an alkoxy group, a nitro group, a cyano group or a halogen atom.

As the host liquid crystal substance used in the liquid crystal composition of the present invention,
Any of the liquid crystals shown in Table 1 or a mixture thereof may be used. For example, the liquid crystal sold under the trade name ZLI-1132 by Merck and the liquid crystal sold under the trade name ZLI-1565, or the British Drug The liquid crystal sold by House under the product name E-7 is used.

In addition, a cholesteric state can be obtained by adding an optical rotatory substance described later to such nematic liquid crystal.

As the optically active substance used in the liquid crystal composition of the present invention, a chiral nematic compound, for example, a 2-methylbutyl group,
There is a compound in which an optically active group such as a 3-methylbutoxy group, a 3-methylpentyl group, a 3-methylpentoxy group, a 4-methylhexyl group and a 4-methylhexoxy group is introduced into a nematic liquid crystal. In addition, l-shown in JP-A-51-45546
Alcohol derivatives such as menthol and d-borneol,
Ketone derivatives such as d-cynolone, 3-methylcyclohexane, carboxylic acid derivatives such as d-citronellic acid and 1-cynonoic acid, aldehyde derivatives such as d-citronellal, alkene derivatives such as d-linonene, other amines, amides, Optically active substances such as nitrile derivatives can be used.

As a device for displaying a liquid crystal using the liquid crystal composition of the present invention, a known liquid crystal display device can be used. That is, generally, at least one of the two transparent glass substrates is provided with a transparent electrode of an arbitrary pattern on two glass substrates, and the two glass substrates are parallel to each other via an appropriate spacer so that the electrode surfaces face each other. An element is used. In this case, the spacer determines the gear gap of the element. The element gap is preferably 1 to 100 μm, particularly 2 to 50 μm from a practical viewpoint.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to such embodiments.

It should be noted that the order parameter (S) of the dye compound can be experimentally obtained from the following formula, if the order parameter showing dichroism is briefly explained.

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

The order parameter (S) is
It is a value indicating the display contrast of the host type liquid crystal element,
As this value theoretically approaches 1, the residual color level of the white areas is reduced, and a clear display with a bright and large contrast becomes possible.

Example 1 Dibromoanthraquinone compound represented by the following structural formula
2.7 g, pn-butylphenol Mix a mixture of 20 ml and 0.1 g of potassium hydroxide in a nitrogen stream at 160
The temperature was raised to ℃ and reacted for 6 hours.

After the reaction, the mixture was cooled, methanol was added thereto, the precipitated crystals were filtered, washed with water, and then dried.

The product was subjected to column chromatography using silica gel (manufactured by Wako Pure Chemical Industries, Ltd .; C-200 trade name) as a carrier and chloroform as a separation solvent to separate and purify impurities, and the following structural formula: 0.5 g of the compound represented by The compound had a melting point of 157-158 ° C.

The anthraquinone-based compound (dye) of the present invention obtained above was added to the above-mentioned mixed liquid crystal ZLI-1565 (trade name of Merck & Co., Inc.) and heated to 70 ° C. or higher in a state where the liquid crystal became an isotropic liquid. After stirring well, the step of standing and cooling was repeated to dissolve the compound (dye).

The liquid crystal composition of the present invention thus prepared has a transparent electrode and is coated with a polyamide resin on the surface in contact with the liquid crystal and then rubbed to be subjected to a homogeneous alignment treatment.
It was enclosed in an element with a gap between substrates of 10 μm consisting of a single glass substrate. In the element subjected to the above-mentioned alignment treatment, the liquid crystal was in a homogeneous alignment state when no voltage was applied, and the dye molecules also had the same alignment according to the host liquid crystal.

The absorption spectrum of the guest-host device prepared in this manner was measured using light polarized parallel to the alignment direction of the liquid crystal molecules and light polarized perpendicular to the alignment direction of the liquid crystal molecules. The absorption wavelength was determined. In determining the absorbance of the dye, the absorption by the host liquid crystal and the glass substrate and the reflection loss of the device were corrected.

Also, using A and A⊥ for each polarization, The value of the order parameter (S) was calculated from

The above results are shown in No. 1 of Table 2 below.

Example 2 Dibromanthraquinone compound used in Example 1.
3g, pn-pentylphenol 50ml, potassium hydroxide
0.12 g and 0.05 g of a nonionic surfactant (manufactured by Kao Atlas Co., Ltd .; trade name Emulgen 108) were used, and otherwise the same as in Example 1, followed by the following structural formula: 3.6 g of the compound shown by The compound had a melting point of 160-161 ° C.

In the same manner as in Example 1, the maximum absorption wavelength (λmax) and the order parameter (S) were measured and calculated.
These results are shown in No. 2 of Table 2 below.

Example 3 By the method according to Example 1, No. 3 in Table 2 below.
No. 25 to the anthraquinone compound (dye) of the present invention having the respective structural formulas were produced and isolated. The maximum absorption wavelength (λmax) and the order parameter (S) were measured and calculated in the same manner as in Example 1 except that the obtained 23 kinds of dye compounds were used.

The above results are summarized in No. 3 to No. 25 in Table 2 below.

(Effect of the Invention) The anthraquinone-based compound of the present invention exhibits a high dichroic ratio and good solubility in liquid crystals as a dye compound that dissolves in liquid crystals and performs color display by the guest-host effect.
A liquid crystal composition using the present dye compound can provide good color display.

Claims (2)

[Claims] 1. A general formula [I] (In the formula, one of X and Y represents an amino group and the other represents a hydroxyl group, and R ¹ is (R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group, and n is 1
Represents an integer of ~ 4. ), R ² and R ³ are hydrogen atoms,
It represents an alkyl group that may be substituted with an alkoxy group or an alkoxy group that may be substituted with an alkoxy group, and the alkoxy group of this substituent may be substituted with an alkoxy group. ) An anthraquinone compound represented by. 2. A general formula [I] (In the formula, one of X and Y represents an amino group and the other represents a hydroxyl group, and R ¹ is (R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group, and n is 1
Represents an integer of ~ 4. ), R ² and R ³ are hydrogen atoms,
It represents an alkyl group that may be substituted with an alkoxy group or an alkoxy group that may be substituted with an alkoxy group, and the alkoxy group of this substituent may be substituted with an alkoxy group. ) A liquid crystal composition comprising an anthraquinone compound represented by