JPH1088143A - Dichromic color, liquid crystal composition containing the same and liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel azo dichromic color which has high dichroism and coloring power, shows deep hue of red to blue and is useful as a display element excellent in contrast and durability. SOLUTION: This compound is represented by formula I (R<1> and R<2> are each H, an alkyl, an alkoxyalkyl; R<1> and R<2> may incorporate to form a nitrogen atom-containing aliphatic ring; X is F, an alkoxy, an alkylmercapto, m is 1 or 2; n is 0-2 where m+n is 2 or 3; Z<1> -Z<6> are H, halogen, methyl, methoxy; Z<2> and Z<3> or Z<5> and Z<6> may connect to each other to form an aliphatic ring; R<1> and Z<4> or R<2> and Z<6> may incorporate to form a nitrogen atom-containing aliphatic ring), typically the compound of formula II. The compound of formula I is prepared, for example, by the coupling reaction between a compound of formula III and N,N-diethylaniline.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel red-blue azo dichroic dye, a liquid crystal composition containing the same, and a liquid crystal device.

[0002]

2. Description of the Related Art At present, various display modes such as a twisted nematic (TN) type display mode and a super twisted nematic (STN) type display mode have been proposed as liquid crystal displays. Among them, the guest-host (GH) display mode in which a dye is dissolved in a liquid crystal is widely used as a display panel of an automobile or the like because of features such as a wide viewing angle and brightness.

The properties of the dichroic dye used in the GH mode are required to be excellent in the following items: 1) dichroism 2) solubility 3) light resistance 4) coloring power. On the other hand, as red-blue dichroic dyes necessary for forming a black liquid crystal composition having a large market need, conventionally, dyes having an alkyl group, a nitro group or a cyano group at a terminal are known. I was

[0004]

However, conventional dichroic dyes having a nitro group or a cyano group have great disadvantages in light resistance and solubility, and dyes having an alkyl group have a light color such as yellowish red. And it is difficult to obtain a deep hue such as bluish red to blue.

Further, there is a problem that these conventional dyes do not have a sufficient affinity such as solubility for a fluorine-based liquid crystal compound used in recent TFT liquid crystal devices and the like. An object of the present invention is to provide a red to blue dichroic dye having less of the above-mentioned difficulties, and a liquid crystal composition and a liquid crystal element containing the same.

[0006]

An object of the present invention is to provide a diazo or trisazo dichroic dye represented by the following general formula (I):

[0007]

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(Wherein R ¹ and R ^{2 each} have a hydrogen atom, an alkyl group, an alkoxyalkyl group, a fluoroalkyl-substituted alkyl group, or a substituent such as an alkyl group, an alkoxyalkyl group, an alkoxy group, a halogen atom, etc.) R ¹ and R ² are linked to each other to form a nitrogen-containing aliphatic ring, and X is a fluorine atom, an alkoxy group, a fluoroalkyl-substituted alkoxy group, or an alkyl mercapto group , An alkylamino group, a dialkylamino group, or an alkylsulfonyl group, m is 1, 2, n is a number of 0 to 2, m + n is 2, 3, Z ^{1 to} Z ⁶ are a hydrogen atom, a halogen atom, a methyl group, or indicates a methoxy group, or Z ² and Z ^3, or Z ⁵ and Z ⁶ are each other connected to an aliphatic ring, an aromatic ring or a nitrogen-containing aromatic ring Formation is. Alternatively, R ¹ and Z ⁴
And R ² and Z ⁶ are linked together to form a nitrogen-containing aliphatic ring. ) And a liquid crystal composition comprising the same and a liquid crystal element in which at least one of the liquid crystal compositions is sandwiched between transparent substrates.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The dichroic dye of the formula [I] of the present invention can be synthesized, for example, by the following synthesis routes A to C. Route A

[0010]

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Route B

[0012]

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Route C

[0014]

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The deoxidizing agent in the synthesis routes A to C is appropriately selected depending on the type of XH. For example, when XH is an alcohol, a metal alkoxide or the like is used as a deoxidizing agent, and XH
When X is an amine, XH itself also functions as a deoxidizing agent. In the general formula [I], R ¹ and R ² each independently represent a hydrogen atom, methyl, ethyl, linear or branched propyl, butyl, hexyl, octyl, etc.
Alkyl group, ethoxymethyl, butoxymethyl, ethoxyethyl, alkoxyalkyl group such as butoxyethyl, perfluoroethylmethyl, perfluorobutylethyl, fluoroalkyl-substituted alkyl group such as perfluorohexylethyl, benzyl, phenethyl, 4-butyl Aralkyl groups such as benzyl, 4-butoxybenzyl, 4-pentoxybenzyl, 4-chlorobenzyl, or cyclohexylmethyl, cyclohexylethyl,
Cyclohexylalkyl groups such as -butylcyclohexylmethyl, 4-butoxyethylcyclohexylmethyl, 4-pentylcyclohexylmethyl, 4-pentoxycyclohexylmethyl and 4-chlorocyclohexylmethyl; and R ¹ and R ² are linked to each other. To form a nitrogen-containing aliphatic ring such as a pyrrolidine ring, a piperidine ring, and a morpholine ring.

Z ² and Z ³ or Z ⁵ and Z ⁶ may be linked to each other to form an aliphatic ring portion of a tetralin ring, an aromatic ring portion of a naphthalene ring or a nitrogen-containing aromatic ring portion of a quinoline ring. , R ¹ , Z ⁴ and R ² , Z ⁶ may be linked to each other to form a nitrogen-containing aliphatic ring moiety of a julolidine ring or a tetrahydroquinoline ring.

X is a fluorine atom, a C1-C18 alkoxy group such as methoxy, ethoxy, linear or branched propoxy, butoxy, hexyloxy, octyloxy, etc .; a C1-C10 perfluoroalkyl group; Fluorobutylmethoxy group, fluoroalkyl-substituted alkoxy group such as perfluorohexylethoxy group, methyl mercapto, butyl mercapto, hexyl mercapto,
Alkylmercapto groups such as octylmercapto group, alkylamino groups such as methylamino, ethylamino, butylamino, octylamino group, dialkylamino groups such as dimethylamino, diethylamino, dibutylamino, dioctylamino, hexylmethylamino group, and methylsulfonyl And alkylsulfonyl groups such as ethylsulfonyl, butylsulfonyl and octylsulfonyl groups.

Among the dichroic dyes of the present invention, disazo dyes are particularly useful as a component of a black liquid crystal composition because they have a red-purple dyeing hue even in a red dye.
The liquid crystal composition of the present invention comprises an azo dichroic dye represented by the general formula [I] described above [Liquid crystal device handbook; edited by the 142nd Committee of the Japan Society for the Promotion of Science (1989); p154-p.
192, p715 to p722], and easily prepared by mixing with various liquid crystal compounds or liquid crystal compositions such as biphenyl, phenylcyclohexane, phenylpyrimidine, and cyclohexylcyclohexane exhibiting a nematic or smectic phase according to a known method. can do. Examples of such a liquid crystal compound include compounds described in JP-A-3-14892. In addition, the azo dichroic dyes of the present invention are
Fluorine-based liquid crystals can be suitably used because they have excellent solubility in fluorine-based liquid crystals used in FT liquid crystal devices and the like.

The content of the dichroic dye in the liquid crystal composition of the present invention is from 0.1 to 15% by weight, preferably from 0.5 to 5% by weight, based on the composition. The liquid crystal composition of the present invention may contain an optically active compound such as cholesteryl nonanoate, or may contain various additives such as an ultraviolet absorber and an antioxidant.

The liquid crystal composition obtained as described above is sandwiched between at least one of the transparent substrates with electrodes, so that a device utilizing the guest-host effect [Shoichi Matsumoto, Ichiyo Tsunoda “Latest Technology of Liquid Crystals” "Industry Research Council, 34 (198
3); L. Fergason, SID85Dige
st, 68 (1985), etc.]. The substrate is usually a glass plate or acrylic resin,
Various synthetic resin plates such as a polycarbonate resin and an epoxy resin are mentioned, and an electrode layer is formed on the substrate. As the transparent electrode layer, one composed of a metal oxide such as indium oxide, indium tin oxide (ITO), and tin oxide is usually used. The surface of the transparent electrode layer in contact with the liquid crystal is subjected to an alignment treatment as necessary. As the method of the alignment treatment, for example, a method of applying octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, hexadecyltrimethylammonium bromide or the like for vertical alignment, or a method of applying polyimide for parallel alignment. A method of rubbing with a cotton cloth, a degreased surface or the like to make parallel alignment, a method of depositing SiO at an oblique angle to make parallel alignment, and the like are appropriately used. The substrates are integrated via a spacer or the like so that the surfaces of the alignment treatment layers face each other.
Constituting elements having an element spacing of 0 μ, preferably 1 to 15 μ,
Liquid crystal is sealed in the space between the elements.

[0021]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 Phenylazoaniline derivative of the following structural formula [1-1]

[0022]

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1 mmol was dissolved in 15 ml of acetone, 6 mmol of hydrochloric acid was added thereto, and 5 ml of an aqueous solution in which 1 mmol of sodium nitrite was dissolved was added at 0 ° C., followed by stirring for 1.5 hours. 1 mmol of N, N-diethylaniline and 2 g of sodium acetate were added thereto, and
The reaction was performed at night. The reaction mixture was discharged into water, and the precipitate was collected by filtration, purified by column chromatography with a mixed solvent of chloroform and hexane, and recrystallized from the same solvent to obtain the following structural formula [1-2].

[0024]

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A dye having an mp of 180-181 ° C. was obtained. This azo dye was used under the trade name ZLI-1565 (E.
A red guest-host type liquid crystal composition was prepared by dissolving it in a phenylcyclohexane-based liquid crystal mixture commercially available as MERCK Co., Ltd.) at a concentration of 1 wt%. A glass substrate with a transparent electrode, which was coated with a polyimide resin, cured and rubbed, faced, and was sealed in a cell having a gap of 9 μm so that the liquid crystal was aligned in parallel.

The absorbance (A //) of this red-colored cell with respect to linearly polarized light parallel to the orientation direction and the absorbance (A⊥) with respect to linearly polarized light perpendicular to the orientation direction were measured, and the absorption peak (λmax: 525 nm) was obtained. The order parameter (S) at the following equation

[0027]

S = (A // − A⊥) / (A // + 2A⊥)

As a result, S = 0.72.
Trade name ZLI-479 in place of ZLI-1565 above
As a result of similarly determining the order parameter using a fluorine-based liquid crystal mixture commercially available as 2 (manufactured by E. MERCK), S = 0.74 (λmax: 521 n
m).

Example 2 The dye 0.2 represented by the structural formula [1-2] shown in Example 1 was obtained.
4 mmol was dissolved in 30 ml of butanol, and 0.24 mmol of sodium butoxide was added thereto.
After reacting for hours, it was released into water and extracted with dichloromethane. The extract was washed with water, dried and then subjected to column chromatography purification with a toluene-cyclohexane mixed solvent,
Recrystallized from chloroform-hexane, the following structural formula [2
-1]

[0030]

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A dye having an mp of 188-189 ° C. was obtained. The trade name of this dye, ZLI-4792 (E. MER)
The order parameter (S) in a fluorine-based liquid crystal commercially available as CK Corporation was determined in the same manner as in Example 1, and the result was 0.76 (λmax: 514 nm). Example 3 Phenylazoaniline derivative of the following structural formula [3-1]

[0032]

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1.4 mmol was dissolved in 3 ml of a mixed solvent of acetic acid and propionic acid (mixing ratio 1: 5).
4 mmol of sodium nitrite and 1.7 ml of 70% sulfuric acid
Was added at 0 ° C., and reacted at the same temperature for 2.5 hours with stirring. Add 7 to this reaction mixture.
A suspension mixture containing 40 ml of 0% ethanol, 1.4 mmol of N, N-diethylaniline, 0.5 ml of propionic acid and 3 g of sodium acetate was added at 0 ° C., and 0-20
The reaction was carried out overnight at ℃. The reaction mixture was discharged into water, and the precipitate was collected by filtration, purified by column chromatography with a mixed solvent of chloroform and hexane, and recrystallized from the same solvent to give the following structural formula [3-2]

[0034]

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A dye having the following formula: mp 230-231 ° C. was obtained. The trade name of this dye, ZLI-4792 (E. MER)
The order parameter (S) in a fluorine-based liquid crystal commercially available as CK Corporation) was determined in the same manner as in Example 1, and the result was 0.73 (λmax: 553 nm).

Example 4 The dye 0.2 of the structural formula [3-2] shown in Example 3 obtained in Example 3
4 mmol was dissolved in 30 ml of butanol, and 0.24 mmol of sodium butoxide was added thereto.
After reacting for hours, it was released into water and extracted with dichloromethane. The extract was washed with water, dried and then subjected to column chromatography purification with a toluene-cyclohexane mixed solvent,
After recrystallization from chloroform-hexane, the following structural formula [4
-1]

[0037]

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A dye having an mp of 124 ° -126 ° C. was obtained. The trade name of this dye, ZLI-4792 (E. MER)
The order parameter (S) in a fluorine-based liquid crystal commercially available as CK) was determined in the same manner as in Example 1, and the result was 0.75 (λmax: 543 nm).

Example 5 An azo dye shown in the following Table 1 was produced by the method according to the above-mentioned Example 1, and a fluorine-based liquid crystal mixture of each dye: trade name ZLI-4792 (trade name, manufactured by E. MERCK) was used. Was calculated in accordance with Example 1. Table 1 shows the obtained order parameters (S) and hues. In Table 1 below, the alkyl group and the fluoroalkyl group are linear unless otherwise specified.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

EFFECT OF THE INVENTION Contrast and durability can be obtained by the dichroic dye having high dichroism and high tinting strength of the present invention and exhibiting a red to blue deep hue, and a fluorine-based liquid crystal composition containing the same. A liquid crystal element such as a display element having excellent properties can be formed.

Claims (3)

[Claims] 1. A compound represented by the following general formula [I](Where R¹, R^TwoAre each independently a hydrogen atom,
Group, alkoxyalkyl group, fluoroalkyl-substituted
Alkyl group, or alkyl group, alkoxyalkyl group,
Having a substituent selected from an alkoxy group and a halogen atom
Aralkyl or cyclohexylalkyl
Or R¹, R^TwoAre connected to each other and contain nitrogen
Forms an aliphatic ring. X is a fluorine atom, an alkoxy group,
Fluoroalkyl-substituted alkoxy group, alkyl mercap
Group, alkylamino group, dialkylamino group, alkyl
Represents a rusulfonyl group, m is 1, 2 and n is a number of 0 to 2
And m + n is 2, 3, and Z¹~ Z⁶Is hydrogen
Atom, halogen atom, methyl group, methoxy group,
Or Z ^TwoAnd Z^ThreeOr Z^FiveAnd Z⁶Are interconnected and aliphatic
Form a ring, aromatic ring or nitrogen-containing aromatic ring. Or,
R¹And Z^FourAnd R^TwoAnd Z⁶Are connected to each other
Forms an aliphatic ring. ) Disazo or tri represented by
Suazo dichroic dye. 2. A liquid crystal composition comprising a liquid crystal compound and the disazo or trisazo dichroic dye according to claim 1. 3. A liquid crystal device comprising the liquid crystal composition according to claim 2 sandwiched between two substrates with electrodes, at least one of which is transparent.