JPH05213827A - Terphenyl compound and chiral smectic liquid crystal composition using the same - Google Patents

Abstract

PURPOSE:To provide an optically active compound having very large spontaneous polarization, useful as a component for chiral smectic liquid crystal compositions for liquid crystal image display of excellent responsiveness. CONSTITUTION:The objective compound of formula I (R<1>* and R<2>* are each 4-20C optically active group), e.g. a S-(+)-1-methylheptyl[3-hydroxy-4''-(S-(+)-1- methylheptyloxycarbonyl)-3-hydroxy]-p-terphenyl-4-carboxylate. The compound of the formula I can be obtained by coupling reaction between (A) an aromatic halide of formula II produced from p-dibromobenzene and 4-aminosalicylic acid as starting materials and (B) an aromatic trialkyltin compound of formula III using a transition metal catalyst. Using compositions containing the compound of the formula I, light switches or light shutters with operational display of high image quality and quick responsiveness can be obtained.

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 having excellent responsiveness for image display, and a chiral smectic liquid crystal composition for liquid crystal image display having excellent responsiveness containing the same.

[0002]

2. Description of the Related Art With the progress of information society, display devices of information equipment such as personal computers and word processors are widely used. Among them, the liquid crystal display is a thin, flat, lightweight, low-voltage drive, low power consumption, and other advantages. In addition, it is clear without any focus shift, and it is a light-receiving type that does not emit light itself, so it is easy to see in bright places such as outdoors. It has advantages such as above, and is occupying a typical position of display devices. However, the TN (Twisted-nematic) type, which is the display method of the liquid crystal display currently used, has a drawback that the response speed is slow in principle or there is no memory property, so that a high-quality operation display can be obtained. Difficult,
It is difficult to apply it to optical communication and optical shutter devices that require high-speed response. Therefore, various new liquid crystal display methods have been tried in place of the TN type display method, and one of them is a display method using a ferroelectric liquid crystal (NA Cla.
rk et al .; Applied Phys. Lett. 8
6,899 (1980)). This method is a ferroelectric liquid crystal chiral smectic C phase (hereinafter abbreviated to Sc ^* phase.) Or chiral smectic H phase (hereinafter, S _H
^* Abbreviated as phase. ), It is possible to achieve a 1000 times faster response than the TN type display system due to the interaction between the spontaneous polarization and the applied voltage, and the display memory can be obtained even when the power is turned off. Liquid crystal compounds are being actively developed.

By the way, the response time τ of the ferroelectric liquid crystal is
Approximately τ = η / Ps × E ... [2] (where η is viscosity, Ps is spontaneous polarization, and E is electric field strength) is given by the equation [2]. Therefore, if the electric field strength is constant, the larger the spontaneous polarization is, the faster the response is. Generally, it is the dipole in the minor axis direction of the molecule that contributes to spontaneous polarization.
A molecular structure with as large a dipole as possible is desirable. Therefore, in order to increase the spontaneous polarization, many methods of introducing a plurality of substituents having a large dipole in the vicinity of the asymmetric center have been tried, but those Sc ^* compounds have a large viscosity and Ferroelectric liquid crystal compounds that have a substantially large spontaneous polarization and are excellent in high-speed response have been obtained because, for example, the dipoles face in opposite directions due to steric factors and cancel out the effects. The current situation is that there are none.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid crystal display device having a large spontaneous polarization and an excellent high-speed response. The present invention provides an optically active compound and a chiral smectic liquid crystal composition containing the same.

[0005]

The above-mentioned object is achieved by an optically active compound represented by the following general formula [1] and a chiral smectic liquid crystal composition containing 2 mol% or more thereof.

[Chemical 2] (In the formula, R ₁ ^* and R ₂ ^* represent an optically active group having 4 to 20 carbon atoms. N represents an integer of 1 or 2.) Next, the present invention will be described in detail.

The optically active compound of the present invention is represented by the above general formula [1], and R ₁ ^* and R ₂ ^* are both
Although it is an optically active group having 4 to 20 carbon atoms, an alkyl group having 5 to 16 carbon atoms is preferable from the orientation of liquid crystal molecules,
The positions of the asymmetric carbons are preferably the same because they are bonded to the ester group directly or via one carbon, and if their absolute configurations are opposite to each other, spontaneous polarization is canceled and the size becomes smaller. Further, the portion excluding the asymmetric carbon is preferably linear. Examples of desirable optically active groups include the following structures.

[0007]

[Chemical 3]

[Chemical 4]

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12]

As is clear from the general formula [1], the compound of the present invention has a large dipole carbonyl group in the vicinity of two optically active moieties. Moreover, by introducing hydroxyl groups at both ortho positions, the number of dipoles that induce spontaneous polarization is increased, and further, due to intramolecular hydrogen bonding between the hydroxyl group and the carbonyl group, those dipoles are fixed in the same direction. Have a structure. Therefore, a chiral smectic liquid crystal composition containing them makes it possible to fabricate a liquid crystal element characterized by extremely large spontaneous polarization and high-speed response. The optically active compound of the present invention may be produced by appropriately combining conventionally known methods, and is achieved, for example, by the following synthetic route.

[0009]

[Chemical 13]

That is, a) conversion of paradibromobenzene, or 4,4'-dibromobiphenyl to parabromophenylboronic acid or 4'-bromobiphenyl-4-boronic acid, b) conversion of the amino group of 4-aminosalicylic acid. Iodine conversion, c), d) esterification of 4-iodosalicylic acid with optically active alcohol, e) trialkyltin substitution of aromatic halogen, f) coupling reaction of aromatic halogen compound with aromatic boronic acid, g) It consists of 7 steps of a coupling reaction of an aromatic trialkyl tin compound and an aromatic halide.

First, in the reaction a), an organometallic compound is synthesized from paradibromobenzene or 4,4'-dibromobiphenyl. In general, magnesium, copper, zinc, lithium, boron, tin, aluminum and the like are used as the metal of the organometallic compound, but the organometallic compound of the present invention has two halogen atoms in the aromatic ring and only one of them is used. After being converted into a metal, a boron or tin metal is preferable because it selectively undergoes a coupling reaction with other aromatic halogen compounds, and boron is particularly preferable in terms of reaction conditions, stability, reaction yield, and the like. The metal reagent used is preferably trialkoxyborane. First, a halogen-lithium exchange reaction is performed with an equimolar amount of alkyllithium, and then trialkoxyborane is reacted to give para-bromophenylboronic acid or 4'-dibromobiphe 4'-. Bromobiphenyl-4-boronic acid. The amount of trialkoxyborane used is 1.0 to 3.0 times mol, and more preferably 2.0 to 3.0 times mol from the reaction yield. As the reaction solvent, fully dehydrated diethyl ether or tetrahydrofuran is used. First, the halogen-lithium exchange reaction is performed at a reaction temperature of −90 to −50 ° C. for 0.2
Achieved in ~ 3.0 hours. Next, it is preferable that the exchange reaction from lithium to boronic acid is first carried out at -90 to -50 ° C and the temperature is gradually raised to room temperature, and the reaction time is 5
~ 24 hours are preferred.

Next, in the reaction of b), the amino group of 4-aminosalicylic acid is converted to a diazonium salt and then converted to iodine. First, a 50% aqueous sulfuric acid solution is used as a reaction solvent, 4-aminosalicylic acid is dissolved, and then a diazonium salt is formed with an aqueous sodium nitrite solution. Sodium nitrite to be added may be equimolar to 4-aminosalicylic acid, the reaction temperature is 0 to 5 ° C., and the reaction time is 1 to 3 hours. Next, in order to convert the diazonium salt into iodine, copper (I) iodide potassium iodide, sodium iodide, etc. are generally used. In the case of the present invention, potassium iodide is used in consideration of reaction yield, solubility and the like. Is preferred, and the amount used is 1.
It is preferably 5 to 3.0 times mol. The reaction is carried out in an aqueous solution, the reaction temperature is preferably room temperature, and the reaction time is preferably 1 to 3 hours.

Next, the reaction of c) and d) is an esterification reaction of 4-iodosalicylic acid with an optically active alcohol. As a synthetic method, a dehydration reaction with an acid catalyst or a dehydration condensation agent such as dicyclohexylcarbodiimide is used. Examples thereof include a reaction used and a method of converting an aromatic carboxylic acid to an acid chloride with thionyl chloride and then esterifying. Among them, a dehydration condensing agent is used from the viewpoint of simplicity of reaction apparatus, operation, etc. and reaction yield. The method is preferred. The amount of the dehydration-condensation agent used is preferably the same as that of the aromatic carboxylic acid and the optically active alcohol, and 0.1 mol of dimethylaminopyridine or 4-pyrrolidinopyridine should be added as an activation catalyst. Is more preferable. The reaction solvent is preferably fully dehydrated diethyl ether or tetrahydrofuran, and more preferably tetrahydrofuran because of its solubility and reactivity with respect to the substrate. However, since the aromatic carboxylic acid has a hydroxyl group at the 2-position and the esterification reaction between the same molecules also progresses, the method for adding the reagent is first to use an optically active alcohol, a dehydration condensation agent, and an activation catalyst as reaction solvents. A method in which 4-iodosalicylic acid, which is dissolved and finally dissolved in the same solvent, is slowly added dropwise is preferable. The reaction temperature is room temperature, and the reaction time varies depending on the optically active alcohol used, but is achieved in 1 to 24 hours.

Next, in the reaction of e), an organometallic compound is synthesized from the aromatic halide obtained in d). The organometallic compound used is preferably a boron or tin compound because it undergoes a coupling reaction with an aromatic halide. Among them, tin is most preferable because it has a carboxylic acid ester as a substituent and therefore selectively reacts only with bromine or iodine of the aromatic halogen. As the metal reagent used, hexaalkyltin is preferably used, and the amount used is 1.0 to 8.0 times the mol of the aromatic carboxylic acid ester, but 1.5 to 3 times from the reaction yield. A mole of 5 times is preferable. For the reaction, it is preferable to use a divalent or zero-valent Pd catalyst, and among them, tetrakis (triphenylphosphine) palladium, which is a zero-valent Pd catalyst, is more preferable from the conditions such as reaction time and reaction yield. The amount used may be 0.01 to 0.1 times mol. As the reaction solvent, an aromatic solvent such as sufficiently dehydrated toluene is used, and the temperature is 70 to 100 ° C., preferably 80 to 100 ° C.
The reaction is carried out at a reaction temperature of 100 ° C., and the reaction time is preferably 2 to 6 hours.

Next, the reaction f) is a transition metal-catalyzed coupling reaction between the aromatic boronic acid obtained in a) and the aromatic halide obtained in c). The halide used for the coupling reaction with the boronic acid is bromine or iodide, but since the boronic acid has bromine in the para position, the aromatic halide is preferably iodide, which has higher reactivity. The catalyst used in the reaction may be the same as in e). The reaction is preferably carried out in an aromatic solvent such as benzene and toluene in the presence of a base, and a small amount of ethanol is preferably added in view of solubility in the substrate. The mixing ratio of ethanol to benzene is preferably benzene / ethanol = 20/1 to 10/1. Further, the basic aqueous solution to be added is preferably sodium carbonate, sodium acetate, sodium hydroxide, etc. Among them, sodium carbonate is most preferable from the reaction yield. The addition amount thereof is preferably 2.0 to 3.0 times mol. The reaction is carried out under reflux and the reaction time is 1
-10 hours, more preferably 8-10 hours.

Finally, the reaction of g) is

It is a coupling reaction between an aromatic trialkyl tin represented by [9] and an aromatic halide represented by the formula [10], and is achieved by using a transition metal catalyst. The catalyst used is preferably a divalent or zero-valent Pd catalyst or a divalent Ni catalyst. Among them, dichlorobis (triphenylphosphine) palladium, which is a divalent Pd catalyst, is selected depending on conditions such as reaction time and reaction yield. Is most preferable, and the amount used is 0.01
It may be up to 0.1 times by mole. The reaction solvent is preferably sufficiently dehydrated tetrahydrofuran or a dehydrated mixed solvent of tetrahydrofuran and hexamethylphosphoric triamide.
The reaction is carried out under reflux, and the reaction time is 1 to 24 hours, more preferably 20 to 24 hours. The products obtained by the reactions a) to g) can be easily separated by appropriately selecting an extraction method, a distillation method, a recrystallization method, a chromatography method or the like which is usually used. The compound of the present invention can be used alone or in combination with another liquid crystal compound exhibiting a smectic C phase to form a chiral smectic liquid crystal composition. As the liquid crystal compound to be mixed, any liquid crystal compound having a smectic C phase can be used, and examples thereof include the following liquid crystal compounds.

[0017]

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30]

[Chemical 31] (However, R represents an alkyl group, and the oxygen atom in the parenthesis may or may not be present.)

The compounding amount of the compound of the present invention is 3 mol% or more,
It is preferably 5 mol% or more, and the liquid crystal compound to be mixed may be one kind or plural kinds, and may be appropriately selected according to the purpose. The chiral smectic liquid crystal composition of the present invention can be formed into a display device by a conventionally known method.

[0019]

INDUSTRIAL APPLICABILITY The optically active compound of the present invention and the chiral smectic liquid crystal composition using the same have extremely large spontaneous polarization, and have a response speed as large as several hundred times that of the conventional TN type display method. By using it, an operation display with high image quality and an optical switch or optical shutter with high-speed response can be obtained. Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 S-(+)-1-methylheptyl- [3 "-hydroxy-4"-(S-(+)-1-methylheptyloxycarbonyl) -3-hydroxy] -paraterphenyl- 4-
Carboxylate production

[Chemical 32] A) Preparation of para-bromophenylboronic acid 7.5 g (31.8 mmol) of para-dibromobenzene was dissolved in 95 ml of dry tetrahydrofuran, and 19.9 ml (31.8 ml) of n-butyllithium hexane solution was dissolved at -78 ° C.
(Mmol) was added dropwise over 30 minutes, and the mixture was further stirred for 1 hour. Next, a mixed solution of 9.9 g (95.4 mmol) of trimethoxyborane and 20 ml of dry tetrahydrofuran was added dropwise, the temperature was gradually raised to room temperature, and the mixture was stirred for 15 hours. After the completion of the reaction, the reaction mixture was extracted with 200 ml of ethyl acetate, washed with water until it became neutral, the solvent was distilled off, and recrystallized from a hexane solution. As a result, 3.7 g (18.4 mmol) of the following compound was obtained. (Yield 58%)

[Chemical 33]

B) 4-iodosalicylic acid-(+)-1-
Preparation of methylheptyl ester 4-aminosalicylic acid 10.0 g (65.0 mmol)
Was dissolved in 130 ml of 50% sulfuric acid aqueous solution, and at 0 ° C., an aqueous solution of sodium nitrite 4.3 g (65.0 mmol) 40
ml was added dropwise to prepare a diazonium salt aqueous solution. The diazonium salt aqueous solution was added with 30.5 g (1
(84.0 mmol) was added dropwise to 150 ml of an aqueous solution, and the mixture was further stirred at room temperature for 3 hours. After completion of the reaction, ethyl acetate 500
After extraction with ml, and washing with a saturated aqueous solution of sodium thiosulfate, the ethyl acetate layer was washed with water until it became neutral.
After distilling off the solvent, the obtained crude product was purified by a recrystallization method with an aqueous methanol solution to give 11.95 g (4
5.0 mmol) was obtained. (Yield 69%)

[Chemical 34] Next, 0.74 g of S-(+)-2-octanol (5.
7 mmol), dicyclohexylcarbodiimide 1.1
35 g of a dry tetrahydrofuran solution containing 7 g (5.7 mmol) and 0.09 g (0.57 mmol) of 4-pyrrolidinopyridi was prepared, and 1.5 g (5.7 mmol) of 4-aminosalicylic acid synthesized above was prepared therein. 15 ml of a dry tetrahydrofuran solution was slowly added dropwise, and the mixture was stirred overnight at room temperature. After completion of the reaction, tetrahydrofuran-insoluble matter was filtered through Celite, and the solvent was distilled off to obtain a crude product which was purified by silica gel column chromatography to obtain 1.55 g (4.1 mmol) of the following compound. (Yield 73%)

[Chemical 35]

C) 4-Tributyltin salicylic acid S-
Preparation of (+)-1-methylheptyl ester 4-iodosalicylic acid S-(+)-1- synthesized in B)
2.0 g (5.3 mmol) of methyl heptyl ester was dissolved in 40 ml of dry toluene, and 9.3 g (15.9 mmol) of hexabutylditin and 0.07 g (0.05) of tetrakis (triphenylphosphine) palladium.
Was added and the mixture was heated with stirring at 90 ° C. for 6 hours. After completion of the reaction, add 100 ml of a saturated aqueous solution of potassium fluoride,
It was extracted with 200 ml of ethyl acetate. The ethyl acetate layer was washed with water until it became neutral, and then the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography to obtain 2.32 g (4.0 mmol) of the following compound. (Yield 81%)

[Chemical 36]

D) Preparation of 4'-bromophenyl-4-salicylic acid S-(+)-1-methylheptyl ester Para-iodosalicylic acid S-(+)-1- synthesized in B).
Methylhexyl ester 1.65 g (4.4 mmol)
And para-bromophenylboronic acid 0.9 synthesized in A)
g (4.4 mmol) was dissolved in a mixed solvent of 60 ml of benzene and 6 ml of ethyl alcohol to give 1.27 of sodium carbonate.
60 ml of an aqueous solution of g (12.0 mmol) and 0.16 g of tetrakis (triphenylphosphine) palladium
(0.13 mmol) was added, and the mixture was heated with stirring under reflux for 10 hours. After completion of the reaction, the mixture was extracted with 200 ml of ethyl acetate, washed with water until it became neutral, and the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography to give 1.59 g (3.9 mmol) of the following compound.
Got (Yield 89%)

[Chemical 37]

E) S-(+)-1-methylheptyl-
Preparation of [3 ″ -hydroxy-4 ″-(S-(+)-1-methylheptyloxycarbonyl) -3-hydroxy] -paraterphenyl-4-carboxylate 4-Tributyltinsalicylic acid S-(+)-1 -Methylheptyl ester and 4'-bromophenyl-4-salicylic acid S-(+)-1-Methylheptyl ester coupling reaction 4-tributyltin salicylic acid S- synthesized by C)
0.65 g of (+)-1-methylheptyl ester (1.
2 mmol) and 0.49 g (1.2 mmol) of 4'-bromophenyl-4-salicylic acid S-(+)-1-methylheptyl ester synthesized in D) were added to 20 ml of dry tetrahydrofuran and dry hexamethylphosphoric acid. Triamide 5
The mixture was dissolved in a mixed solvent (ml), bis (triphenylphosphine) palladium chloride (0.09 g, 0.12 mmol) was added, and the mixture was heated with stirring under reflux overnight. After the reaction was completed, 100 ml of a saturated aqueous solution of potassium fluoride was added, the mixture was extracted with 200 ml of ethyl acetate, washed with water until it became neutral, and the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography to obtain 0.27 g (0.5 mmol) of the following final compound as a liquid. (Yield 3
9%)

[Chemical 38]

Analytical values: i) ¹ H-NMR (proton nuclear magnetic resonance spectrum C
DCl ₃ ) δ (ppm) 0.8-1.85 (m 32H) 5.2
(M 2H) 7.1 to 8.0 (m 10H) 11.1 (s 2H) ii) IR (infrared absorption spectrum) ν (cm ⁻¹ ) 3247, 1690 iii) MS (mass spectrum) m / e 558 (M ⁺ )

Example 2 The optically active compound obtained in Example 1 above was converted into
[7] A chiral smectic liquid crystal composition was manufactured by mixing 10% by mol of the racemic liquid crystal compound represented by the formula.

[Chemical Formula 39] Then, each of these liquid crystal compositions was injected into a polyimide-rubbed cell, and the electric field strength was 4 V / μm.
Polarization (Ps) in the Sc ^* phase when applying the rectangular wave voltage of
And the response time (τ) were measured. The physical property values of each liquid crystal composition are shown in Table 1.

[Chemical 40]

[Table 1]

Claims (2)

[Claims] 1. A general formula [1] (In the formula, R ^{1 *} and R ^{2 *} represent an optically active group having 4 to 20 carbon atoms, and n represents an integer of 0 to 2.). 2. A chiral smectic liquid crystal composition containing 2 mol% or more of the compound represented by the above general formula [1].