JP2002308833A - Optically active compound and liquid crystal composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chiral dopant having such characteristics that the HTP is great, and furthermore the helical pitch to induce becomes shorter with increased temperatures. SOLUTION: An optical active compound is represented by formula (1) wherein X<1> , X<2> , Y<1> , and Y<2> are each a hydrogen atom or a fluorine atom; A is selected from the structural formula group consisting of a single bond (-), -COO-, -O-CH2 CH2 -O-, -COO-Ph(X,Y)-. -Ph(X,Y)-COO-, -OOC-Ph(X,Y)-COO- and-OOC-Np-COO- [wherein -Ph(X,T)- is a 1,4-phenylene group whose 2- or 3-position may be substituted with a fluorine atom; and -Np- is a 2,6-naphthylene group]; and C* is an asymmetric carbon atom}.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optically active compound, a liquid crystal composition containing the same, and a liquid crystal display device using the liquid crystal composition.

[0002]

2. Description of the Related Art Various display modes of a liquid crystal display element are known, and in many of the display modes, control of a helical pitch of a liquid crystal is required. The following modes are required to control the helical pitch of the liquid crystal. Modes that are currently in practical use and frequently used are a twisted nematic mode (TN mode) using a nematic liquid crystal and a super twisted nematic mode (STN mode).

In the TN mode, liquid crystal molecules are oriented so as to be twisted by 90 degrees between an upper substrate and a lower substrate, and a ピ ッ チ pitch of a helix is formed in a cell. In the STN mode, the liquid crystal molecules are oriented so as to be twisted around 220 degrees between the upper substrate and the lower substrate.
/ 5 pitch is formed. The TN mode is used in a simple matrix drive liquid crystal display element and an active matrix drive liquid crystal display element, and the STN mode is used in a simple matrix drive liquid crystal display element.

As another mode, there is a selective reflection (SR) mode of a chiral nematic liquid crystal.
As shown in FIGS. 1 and 2, in the SR mode, the liquid crystal takes a planar state in which the helical axis is perpendicular to the substrate and a focal conic state in which the direction of the helical axis is random.
These two states can be switched by a voltage pulse. In the planar state, light having a wavelength corresponding to the helical pitch is reflected, but in the focal conic state, light passes through the element. Display is possible by making the reflection state bright and the transmission state dark. An optically active compound that induces a helical structure is usually called a chiral dopant. Until now, many chiral dopants have been synthesized,
A typical compound is a compound having the following structure.

[0005]

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The most important performance required of a chiral dopant is to have a large torsional force. The torsional force (HTP) is a physical quantity defined by the following equation. HTP (μm ⁻¹ ) = 1 / ((addition amount of chiral dopant (wt%) / 100) × induced helical pitch (μm)) The chiral dopant usually does not exhibit liquid crystallinity, and
Many have a large molecular weight, and when added in a large amount to the mother liquid crystal, various performances are often deteriorated. Examples of the performance deterioration include a decrease in the phase transition temperature from the isotropic phase to the nematic phase, an increase in the liquid crystal viscosity, and liability to cause crystallization. Chiral dopan with a large torsion force,
Since a desired helical pitch can be obtained with a small amount of addition, deterioration of various performances can be suppressed.

In the SR mode, in addition to these problems, there is a problem that the helical pitch has a temperature dependency. In other words, in the SR mode, light corresponding to the helical pitch is reflected to be in a bright state, but in the chiral dopant developed so far, the helical pitch becomes longer with an increase in temperature, and the color of the reflected light changes. There was a problem.
The change of the selective reflection wavelength with the temperature rise is called "wavelength shift". A case where the selective reflection wavelength becomes longer due to a temperature rise is defined as a positive wavelength shift, and a case where the wavelength becomes shorter as a negative wavelength shift.

In order to eliminate the temperature dependence of the selective reflection wavelength,
A combination of a chiral dopant exhibiting a positive wavelength shift and a chiral dopant exhibiting a negative wavelength shift was studied.However, the number of chiral dopants exhibiting a negative wavelength shift was extremely small, and the amount of the shift was too small. Was difficult. Another method for eliminating the temperature dependence of the selective reflection wavelength is to use a chiral dopant having a small wavelength shift.
However, a chiral dopant that can achieve both the performance of a large helical pitch to be induced and a small wavelength shift has not been found yet.

[0009]

SUMMARY OF THE INVENTION The present invention provides a chiral dopant characterized in that the HTP is large and the pitch of the induced helix becomes shorter as the temperature rises, or the temperature change of the pitch of the induced helix is small. Is to do.

[0010]

That is, the present invention relates to an optically active compound represented by the following general formula (1). In the present invention, in the general formula (1), A is -COO-Ph (X,
It is preferable that all of X, X ¹ , X ² , Y, Y ¹ and Y ² are hydrogen atoms. In addition, the torsional force (HTP) is 14
It is preferable to use an optically active compound exhibiting such properties that the induced helical pitch becomes shorter as the temperature rises or that the induced helical pitch has a wavelength shift of 30 nm or less. This compound is suitably used as an additive for nematic liquid crystals, and is suitably used as a nematic liquid crystal composition containing at least one or more optically active compounds represented by the general formula (1). A liquid crystal element in which an object is sandwiched between substrates having electrodes.

[0011]

Embedded image (Wherein X ¹ , X ² , Y ¹ and Y ² are hydrogen atoms or fluorine atoms, and A is a single bond (-), -COO-, -O-CH ₂ CH ₂ -O-, -COO- Ph
(X, Y)-,-Ph (X, Y) -COO-, -OOC-Ph (X, Y) -COO- and -OO
C-Np-COO- (where -Ph (X, Y)-represents a 1,4-phenylene group in which a 2- or 3-position may be substituted with a fluorine atom,
-Np- represents a 2,6-naphthylene group. ), And C * represents an asymmetric carbon atom. )

Since the optically active compound of the present invention has two asymmetric carbon atoms, there are R, R-form and four kinds of optical isomers of R, S-form, S, R-form and S, S-form. However, R and R bodies and S and S bodies are desirable. The difference in properties between the R, R and S, S forms is the chirality of the induced helix (right helix, left helix)
Is different. Therefore, in use, one of them is selected in consideration of the handiness of the chiral dough pint used in combination.

When a large amount of the optically active compound of the present invention is added alone to a nematic liquid crystal as a mother liquid crystal, the resulting composition may crystallize at room temperature depending on the combination. However, also in this case, usually, other chiral dopants are used in combination, or since it is not essential to fix a combination that produces the same effect, it is easy to prepare a practical composition. Can be avoided.

[0014]

According to the present invention, not only is HTP large,
Whether the pitch of the induced helix becomes shorter with increasing temperature,
Alternatively, the present invention provides a chiral dopant having a characteristic that the value of the change in the induced helical pitch is small even when the change in the helical pitch with temperature rise is long. Therefore, the TN mode, S
In the liquid crystal used in the TN mode, the helical pitch can be adjusted only by adding a small amount of the chiral dopant of the present invention, so that the performance deterioration of the mother liquid crystal can be suppressed. In the SR mode liquid crystal, a chiral dopant that induces a positive wavelength shift is used in combination with the present invention, or only the present invention is used in combination, whereby a liquid crystal having no helical pitch temperature change is used. Can be obtained.

[0015]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is of course not limited thereto. Example 1 (Equation (1): X, X ¹ , X ² , Y, Y ¹ , Y ² = H, A = -COO-Ph-
(E1)) Production of 4-((R) -1-methyl-3-ethylpentyloxycarbonyl) biphenyl = 4 ′-((R) -1-methyl-3-ethylpentyloxycarbonyl) benzoate.

(1) Synthesis of 4'-acetoxybiphenyl-4-carboxylic acid. 4'-hydroxybiphenyl-4-carboxylic acid 50 g (234 mmol)
And 238 g (2.34 mol) of acetic anhydride were charged into the reaction vessel, and 0.1 g of concentrated sulfuric acid was added with stirring. The mixture was stirred until the exotherm stopped, and further heated and stirred at 80 ° C. for 4 hours, and then cooled to room temperature. While cooling in an ice bath, 500 g of water was gradually added, and the mixture was stirred at room temperature for 3 hours to quench unreacted acetic anhydride. The precipitated white solid was separated by filtration, washed with water to remove acetic acid, and dried with a vacuum drier to obtain 59.8 g (99% yield) of 4'-acetoxybiphenyl-4-carboxylic acid.

(2) Synthesis of 4'-acetoxybiphenyl-4-carbonyl chloride. 4'-acetoxybiphenyl-4-carboxylic acid 59.8 g (233.4 m
mol) and 278 g (2.33 mol) of purified thionyl chloride were charged into a reaction vessel, and heated under reflux (79 ° C.) for 4 hours. Next, thionyl chloride was first distilled off under normal pressure, and
(Milliliter), and toluene and thionyl chloride were distilled off under reduced pressure to obtain 63 g of 4'-acetoxybiphenyl-4-carbonyl chloride (yield 98%).

(3) (R) -1-methyl-3-ethylpentyl-4'-
Synthesis of acetoxybiphenyl-4-carboxylate. 4'-acetoxybiphenyl-4-carbonyl chloride 1
8.6 g (67.6 mmol), 8.0 g of (R) -4-ethyl-2-hexanol
(61.4 mmol) and 140 ml of toluene were charged into a reaction vessel,
To this, 9.7 g (122.9 mmol) of pyridine was added dropwise, and the mixture was stirred at room temperature for 3 hours. After adding 40 ml of water to the reaction solution and stirring at room temperature for 30 minutes, the organic layer was separated. The organic layer was washed with 2N hydrochloric acid, a 1N aqueous sodium hydroxide solution and then with water, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off to remove (R) -1-methyl-3-.
Ethylpentyl-4′-acetoxybiphenyl-4-carboxylate 22 g (99% yield) was obtained.

(4) (R) -1-methyl-3-ethylpentyl-4'-
Synthesis of hydroxybiphenyl-4-carboxylate. (R) -1-methyl-3-ethylpentyl-4′-acetoxybiphenyl-4-carboxylate 22 g (59.7 mmol) and toluene
390 ml was charged into a reaction vessel, and a 40% solution of methylamine methanol was added dropwise thereto, followed by stirring at room temperature for 3 hours. The reaction solution was washed and separated with 2N hydrochloric acid and water, the organic layer was dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off to remove (R)-.
19 g (97% yield) of 1-methyl-3-ethylpentyl-4'-hydroxybiphenyl-4-carboxylate was obtained.

(5) 4-((R) -1-methyl-3-ethylpentyloxycarbonyl) biphenyl = 4 '-((R) -1-methyl-3-
Synthesis of ethylpentyloxycarbonyl) benzoate. 2.0 g (6.12 mmol) of (R) -1-methyl-3-ethylpentyl-4′-hydroxybiphenyl-4-carboxylate, 1.8 g (8.86 mmol) of terephthalic acid dichloride and 150 ml of anhydrous dichloromethane were added to the reaction vessel. 3g (37
mmol), and the mixture was stirred at room temperature for 6 hours. In addition to this
1.5 g (11.5 mmol) of (R) -4-ethyl-2-hexanol was added, and the mixture was stirred at room temperature for 18 hours.

50 ml of water is added to the reaction solution, and
After stirring for 2 hours, the organic layer was separated. The obtained organic layer was washed with 2N hydrochloric acid, 1N sodium hydroxide, then with water, dried over anhydrous sodium sulfate, and filtered. The solvent was distilled off from the filtrate, and the obtained crude product was purified by silica gel chromatography to obtain 1.2 g of the target compound (2.04 mm
ol, yield 23%).

Embodiment 2 (Equation (1): X, X ¹ , X ² , Y, Y ¹ , Y ² = H,
A = -Ph-COO- (E2)) 4-((R) -1-methyl-3-ethylpentyloxycarbonyl) phenyl = 4 '-((R) -1-methyl-
Production of 3-ethylpentyloxycarbonyl) -4-biphenylcarboxylate. (1) Synthesis of 4-acetoxybenzoic acid chloride. 100 g (0.555 mol) of 4-acetoxybenzoic acid in thionyl chloride
In addition to 400 g (3.36 mol), the mixture was heated under reflux for 4 hours. Next, after distilling off excess thionyl chloride, distillation under reduced pressure (4 mmHg, 116
° C) and 99g of the target compound (0.498mol, 90% yield)
I got

(2) Synthesis of (R) -4-acetoxy-1- (1-methyl-3-ethylpentyloxycarbonyl) benzene. 4-acetoxybenzoic acid chloride 49g (0.246mol), (R)-
29 g (0.222 mol) of 4-ethyl-2-hexanol and 750 ml of anhydrous toluene were charged into a reaction vessel, and 35 g of pyridine was added thereto.
(0.442 mol) was added dropwise, and the mixture was stirred at room temperature for 15 hours. After adding 300 ml of water to the reaction solution and stirring at room temperature for 1 hour, the organic layer was separated. The obtained organic layer was washed with 2N hydrochloric acid, 1N sodium hydroxide, and then with water. The organic layer was dried over anhydrous sodium sulfate and filtered, and the solvent was distilled off from the filtrate to obtain 63 g (0.215 mol, 97% yield) of the target compound.

(3) Synthesis of (R) -4-hydroxy-1- (1-methyl-3-ethylpentyloxycarbonyl) benzene. 63 g (0.215 mol) of (R) -4-acetoxy-1- (1-methyl-3-ethylpentyloxycarbonyl) benzene was dissolved in 900 ml of anhydrous toluene, and 25 g of a methanol solution of 40% methylamine was added dropwise thereto. Then, the mixture was stirred at room temperature for 5 hours. After the reaction solution was washed with 2N hydrochloric acid and water, the organic layer was separated. The obtained organic layer is dried over anhydrous sodium sulfate,
After filtration, the solvent was distilled off from the filtrate to obtain 49 g of the desired compound.
(0.195 mol, 91% yield).

(4) 4-((R) -1-methyl-3-ethylpentyloxycarbonyl) phenyl = 4 '-((R) -1-methyl-3-ethylpentyloxycarbonyl) -4-biphenylcarboxy Rate synthesis. 3.1 g (12.3 mmol) of (R) -4-hydroxy-1- (1-methyl-3-ethylpentyloxycarbonyl) benzene, 3.1 g (11.1 mmol) of 4,4'-biphenyldicarbonyl chloride and 100 ml of anhydrous dichloromethane 4 g (48 mmol) of pyridine was added dropwise to the reaction vessel, and the mixture was stirred at room temperature for 6 hours. Further to this (R) -4-ethyl-2-hexanol 1.5 g (11.5 mmol)
Was added and stirred at room temperature for 18 hours. Add 50 water to this reaction solution.
After adding 2 ml of the mixture and stirring at room temperature for 2 hours, the organic layer was separated. The obtained organic layer was washed with 2N hydrochloric acid, 1N sodium hydroxide and then with water, and dried over anhydrous sodium sulfate.
After filtration, the solvent was distilled off from the filtrate. The obtained crude product was purified by silica gel chromatography to obtain 2.0 g (3.40 mmol, 30% yield) of the target compound.

Embodiment 3 (Equation (1): X, X ¹ , X ² , Y, Y ¹ = H, Y ² =
F, A = -Ph-COO- (E3)) 3-fluoro-4-((R) -1-methyl
-3-ethylpentyloxycarbonyl) phenyl = 4'-
((R) -1-methyl-3-ethylpentyloxycarbonyl) -4
-Production of biphenylcarboxylate. The procedure was the same as Example 2 except that 4-acetoxy-2-fluorobenzoic acid was used instead of 4-acetoxybenzoic acid in (1) of Example 2.

Embodiment 4 (Equation (1): X, X ¹ , X ² , Y, Y ¹ , Y ² = H,
A = -OOC-Ph-COO- (E4)) Production of 1,4-bis (4-((R) -1-methyl-3-ethylpentyloxycarbonyl) phenyloxycarbonyl) benzene. (R) -4-hydroxy-1 obtained in the same manner as (3) of Example 2
-(1-methyl-3-ethylpentyloxycarbonyl) benzene 3.0 g (11.9 mmol), terephthalic acid dichloride 1.0
g (4.92 mmol) and 50 ml of anhydrous toluene were charged into a reaction vessel, and 2 g (24 mmol) of pyridine was added dropwise thereto.
Stirred for hours. Add 30 ml of water to the reaction solution, and add
After stirring for an hour, the organic layer was separated. The obtained organic layer
Wash with 2N hydrochloric acid, 1N sodium hydroxide, then water,
After drying over anhydrous sodium sulfate, the mixture was filtered, and the solvent was distilled off from the filtrate. The obtained crude product was purified by silica gel chromatography, and 2.2 g of the target compound (3.48 mmol,
(Yield 70%).

Embodiment 5 (Equation (1): X, X ² , Y, Y ¹ = H, X ¹ , Y ² =
F, A = -OOC-Ph-COO- (E5)) 1,4-bis (3-fluoro
Production of -4-((R) -1-methyl-3-ethylpentyloxycarbonyl) phenyloxycarbonyl) benzene. In Example 4, (R) -4-hydroxy-1- (1-methyl-3-
Ethylpentyloxycarbonyl) Instead of benzene,
Example 4 was repeated except that (R) -4-hydroxy-2-fluoro-1- (1-methyl-3-ethylpentyloxycarbonyl) benzene was used.

Embodiment 6 (Equation (1): X ¹ , X ² , Y ¹ , Y ² = H, A = -O
OC-Np-COO- (E6)) 2,6-bis (4-((R) -1-methyl-
Production of 3-ethylpentyloxycarbonyl) phenyloxycarbonyl) naphthalene. (R) -4-hydroxy-1- obtained in the same manner as (3) of Example 2.
(1-methyl-3-ethylpentyloxycarbonyl) benzene 2.6 g (10.3 mmol), 2,6-naphthalenedicarboxylic acid
1.0 g (4.92 mmol) and 50 ml of anhydrous dichloromethane were put into a reaction vessel, and 2.3 g (11.1 mmol) of dicyclohexylcarbodiimide and 4-dimethylaminopyridine were further added.
0.26 g (2.1 mmol) was added, and the mixture was stirred at room temperature for 24 hours.

After adding 20 ml of water to the reaction solution and stirring at room temperature for 1 hour, the insoluble matter was filtered, and diethyl ether was added to separate an organic layer. The obtained organic layer was washed with 2N hydrochloric acid,
The extract was washed with 1N sodium hydroxide and then with water, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off from the filtrate. The obtained crude product was purified by silica gel chromatography to obtain 2.0 g (2.93 mmol, yield 59%) of the target compound.

Example 7 (Equation (1): X ¹ , X ² , Y ¹ , Y ² = H, A = -O
-CH ₂ CH ₂ -O- (E7)) 1,2-bis (4-((R) -1-methyl-
Preparation of 3-ethylpentyloxycarbonyl) phenyl-oxy) ethane 1,2-bis (4-carboxyphenyl-oxy) ethane 1.5
g (4.96 mmol), 1.3 g of (R) -4-ethyl-2-hexanol (9.
98 mmol) and 300 ml of anhydrous dichloromethane were put into a reaction vessel, and 2.3 g (11.1 mmol) of dicyclohexylcarbodiimide and 4-dimethylaminopyridine were further added thereto.
0.26 g (2.1 mmol) was added, and the mixture was stirred at room temperature for 7 days.

After 50 ml of water was added to the reaction solution and the mixture was stirred at room temperature for 1 hour, insolubles were filtered off, and the organic layer was separated.
The obtained organic layer was washed with 2N hydrochloric acid, 1N sodium hydroxide and then with water, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off from the filtrate. The obtained crude product is purified by silica gel chromatography to obtain the desired compound.
0.9 g (1.70 mmol, 34% yield) was obtained.

Example 8 (Equation (1): X ¹ , X ² , Y ¹ , Y ² = H, A = −
(E8)) Production of 4,4′-di-((R) -1-methyl-3-ethylpentyloxycarbonyl) biphenyl. 1.3 g of 4.4'-biphenyldicarbonyl chloride (4.65mmo
l), (R) -4-ethyl-2-hexanol 1.3 g (10.0 mmol)
And 30 ml of anhydrous dichloromethane into the reaction vessel,
1.6 g (20.2 mmol) of pyridine was added dropwise thereto, and the mixture was stirred at room temperature for 10 hours. After adding 20 ml of water to the reaction solution and stirring at room temperature for 2 hours, the organic layer was separated. The obtained organic layer is
The extract was washed with N hydrochloric acid, 1N sodium hydroxide and then with water, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off from the filtrate. The obtained crude product was purified by silica gel chromatography, and 2.8 g of the target compound as an oil (6.00 mm
ol, yield 60%).

Embodiment 9 (Equation (1): X ¹ , X ² , Y ¹ , Y ² = H, A = -C
OO- (E9)) Production of 4-((R) -1-methyl-3-ethylpentyloxycarbonyl) phenyl = 4 '-((R) -1-methyl-3-ethylpentyloxycarbonyl) benzoate. (R) -4-hydroxy-1- obtained in the same manner as (3) of Example 2.
(1-methyl-3-ethylpentyloxycarbonyl) benzene 2.0 g (7.98 mmol), terephthalic acid dichloride 1.6
g (7.88 mmol) and 100 ml of anhydrous dichloromethane were added to the reaction vessel, and 3 g (37 mmol) of pyridine was added dropwise thereto, followed by stirring at room temperature for 6 hours. Further, 1.1 g (8.44 mmol) of (R) -4-ethyl-2-hexanol was added thereto, and the mixture was stirred at room temperature for 18 hours. After adding 50 ml of water to the reaction solution and stirring at room temperature for 2 hours, the organic layer was separated. The obtained organic layer was washed with 2N hydrochloric acid, 1N sodium hydroxide and then with water, dried over anhydrous sodium sulfate, filtered, and the solvent was distilled off from the filtrate. The obtained crude product was purified by silica gel chromatography, and 1.0 g of the target compound (1.95 mmol, yield 24
%).

Optically active compounds obtained in Examples 1 to 9 above
Tables 1 and 2 show the ¹ H-NMR measurement results for (E1 to E9).
The common part of the structural formula and the part A in the general formula are shown in Chemical formula 4, respectively. The phase transition temperature of each optically active compound (E1 to E9) was confirmed by observation with a polarizing microscope and DSC measurement. The results were as follows. E1: Iso (<-40) Cry E2: Iso (35) Cry E3: Iso (12) Cry E4: Iso (<-40) Cry E5: Iso (36) Cry E6: Iso (59) Cry E7: Iso ( <-40) Cry E8: Iso (<-40) Cry E9: Iso (<-40) Cry (where the number in parentheses indicates the phase transition temperature (° C.)
Indicates an isotropic phase, and Cry indicates a crystalline phase. )

Table 1 ¹ H-NMR (δ, ppm) [Common part of general formula] Terminal asymmetric Other benzene ringMethyl carbon Alkyl group Expression left part Expression right part No. 1 2 3 4 5 6 7 8 9 10 (E1): 0.88 5.28 1.21 to 1.81 8.28 8.19 8.28 8.19 7.68 8.12 7.68 8.12 (E2): 0.88 5.27 0.90 to 1.80 8.14 7.75 8.14 7.75 7.31 8.14 7.31 8.14 (E3): 0.89 5.27 1.28 to 1.80 8.15 7.22 8.15 7.72 7.13 − 7.13 8.03 (E4): 0.88 5.26 1.31 to 1.79 8.14 7.33 8.14 7.33 7.33 8.14 7.33 8.14 (E5): 0.88 5.27 1.30 to 1.78 − 7.14 8.04 7.14 7.14 − 7.14 8.04 (E6): 0.88 5.27 1.20 to 1.80 8.20 7.36 8.20 7.36 7.36 8.20 7.36 8.20 (E7): 0.86 5.21 1.29 to 1.76 8.00 6.97 8.00 6.97 6.97 8.00 6.97 8.00 (E8): 0.88 5.27 1.31 to 1.79 8.12 6.68 8.12 6.68 6.68 8.12 6.68 8.12 (E9): 0.87 5.27 1.30-1.81 8.14 8.26 8.14 8.26 7.30 8.14 7.30 8.14

Table 2 ¹ H-NMR (δ, ppm) [A part of general formula] No. 1 2 3 4 5 6 (E1): biphenyl ring 7.33 7.68 7.33 7.68 − − (E2): 〃 7.75 8.29 7.75 8.29 − − (E3): 〃 7.77 8.03 7.77 8.03 − − (E4): Benzene ring 8.35 8.35 8.35 8.35 − − (E5): 〃 8.34 8.34 8.34 8.34 − − (E6): Naphthalene ring 8.20 8.20 8.87 8.87 8.20 8.20 (E7 ): Dimethylene 4.40 4.40 4.40 4.40 − − (E8): − − (E9): − −

[0038]

Embedded image

Example 10 The optically active compounds (E1 to E9) prepared above were treated with H
TP and wavelength shift were measured. 10 wt% of the optically active compound obtained in Example 1 was added to a nematic liquid crystal (ZLI-1565) manufactured by Merck & Co., to prepare a chiral nematic (N *) liquid crystal composition. The upper limit temperature and characteristic reflection behavior of the N * phase of the prepared liquid crystal composition were examined. Finally, the twisting force (H
TP). The maximum temperature of the N * phase was determined by observation with a polarizing microscope and DSC measurement.

The characteristic reflection behavior was performed according to the following procedure. A liquid crystal cell (cell thickness: 10 μm) with an ITO electrode was filled with the liquid crystal composition prepared above in an isotropic phase. The cell was kept at 60 ° C., and a rectangular wave voltage of ± 60 V was applied for about 1 minute, and then rapidly cooled to room temperature to obtain a planar orientation. The characteristic reflection behavior of this liquid crystal cell at 25 ° C. and 60 ° C. was examined using a self-recording spectrophotometer. HTP at 25 ° C. and 60 ° C. was determined by the following equation. HTP (μm ⁻¹ ) = n / (λ ₂₅ × C / 100) HTP (μm ⁻¹ ) = n / (λ ₆₀ × C / 100) where n is the refractive index of the chiral nematic liquid crystal, and λ ₂₅ is
25 ° C. and λ ₆₀ represent the characteristic reflection wavelength (μm) at 60 ° C., and C represents the concentration of the chiral agent (wt%). In addition, the value of the refractive index n adopted ZLI-1565 (1.6) which is a mother liquid crystal.

The wavelength shift was obtained from the following equation. Wavelength shift (nm) = λ ₆₀ ^* −λ ₂₅ ^* where λ ₆₀ ^* is the characteristic reflection wavelength (nm) at 60 ° C., λ
₂₅ ^* represents a characteristic reflection wavelength (nm) at 25 ° C. The optically active compound (E1) of Example 1 had a large HTP of 14 or more, and had a property that the helix became shorter as the temperature increased. Table 3 shows the results obtained by examining the HTP and the wavelength shift of the optically active compounds (E1 to E9) obtained in Examples 2 to 9 in the same manner as described above.

Comparative Examples 1 to 3 HTP and wavelength shift of known compounds CB15, S811 and CN shown in the description of the prior art were measured in exactly the same manner as in Example 10. The known compound is HTP
CB15 and S811 were measured with a composition in which 15 wt% was added to the nematic liquid crystal, and CN was measured with a composition in which 30 wt% was added. The results are shown in Table 3.

Table 3 Compounds Iso-N * (° C.) HTP (1 / μm) Wavelength shift (nm) Example 1 E17917.1-101〃2E28018.1-72〃3E38015.7 −93 ４ 4 E4 81 17.5 -194 ５ 5 E5 81 14.6 -78 〃6 E684 16.1-136 ７7 E777 17.4 -53 ８8E870 19.7 +22 ９9E9 70 18.7 +7 Comparative Example 1 CB15 74 7.9 +193 〃 2 S811 73 10.1 + 7 ３ 3 CN 82 5.2 + 34 Note). Iso-N * changes from the isotropic phase to the chiral nematic phase. Indicates the phase transition temperature (upper limit temperature of N * phase).

[Brief description of the drawings]

Fig. 1 Planar molecular orientation of chiral nematic liquid crystal

Fig. 2 Focal conic molecular alignment of chiral nematic liquid crystal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 19/20 C09K 19/20 19/32 19/32 19/54 19/54 B G02F 1/13 500 G02F 1/13 500 F term (reference) 4H006 AA01 AB64 BJ50 BM30 BM71 BP30 KA06 KF10 4H027 BA01 BD14 BD16 CB10 CC10 CD10 CF10 DK10

Claims (9)

[Claims] 1. An optically active compound represented by the following general formula (1). Embedded image (Wherein X ¹ , X ² , Y ¹ and Y ² are hydrogen atoms or fluorine atoms, and A is a single bond (-), -COO-, -O-CH ₂ CH ₂ -O-, -COO- Ph
(X, Y)-,-Ph (X, Y) -COO-, -OOC-Ph (X, Y) -COO- and -OO
C-Np-COO- (where -Ph (X, Y)-represents a 1,4-phenylene group in which a 2- or 3-position may be substituted with a fluorine atom,
-Np- represents a 2,6-naphthylene group. ), And C * represents an asymmetric carbon atom. ) 2. In the general formula (1), A is -COO-Ph
The optically active compound according to claim 1, which is (X, Y)-. 3. In the general formula (1), X, X ¹ , X ² , Y, Y ¹ , Y
^2. The optically active compound according to claim 1, wherein all ² are hydrogen atoms. 4. The optically active compound according to claim 1, wherein the torsional force (HTP) is 14 or more. 5. The optically active compound according to claim 1, wherein the pitch of the induced helix becomes shorter as the temperature rises (the wavelength shift is negative). 6. The induced helical pitch wavelength shift is
2. The optically active compound according to claim 1, having a thickness of 30 nm or less. 7. An additive for a nematic liquid crystal represented by the general formula (1). 8. A nematic liquid crystal composition comprising at least one optically active compound represented by the general formula (1). 9. A liquid crystal device comprising the nematic liquid crystal composition according to claim 8 sandwiched between substrates having electrodes.