JPH0517409A - Ferroelectric compound and chiral smectic liquid crystal composition using the compound - Google Patents

Abstract

PURPOSE:To provide a new optically active compound having large spontaneous polarization and useful for liquid crystal display element having excellent quick response. CONSTITUTION:The optically active compound of formula I (R<1>* and R<2>* are 4-20C optically active group; (n) is 0 or 2), e.g. 3''-hydroxy-4''-(S-(+)-1- methylheptyloxycarbonyl)-4-(S-(+)-1-methylheptyloxy)-p-terphenyl-4-car boxylate. The compound of formula I can be produced e.g. by producing a compound of formula II from p-iodobenzoic acid and an optically active alcohol, converting the compound into a compound of formula IV via a compound of formula III and reacting the obtained compound of formula IV with a compound of formula VI derived from a compound of formula V.

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

[0002]

2. Description of the Related Art With the development of information society, display devices of information equipment such as personal computers and word processors are widely used. Among them, the liquid crystal display has advantages such as thin, flat, lightweight, low voltage drive, low power consumption, etc. 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 even 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 system 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 high-quality operation is performed. It is difficult to obtain a display, and it is difficult to apply it to optical communication and optical shutter elements that require high-speed response. Therefore, various new liquid crystal display methods have been tried in place of the TN type display method, one of which is a display method using a ferroelectric liquid crystal (NAClar
k et al; Applied Phys. Lett. 86,899 (198
0)). This method is based on a ferroelectric liquid crystal chiral smectic C phase (hereinafter abbreviated as S _C ^* phase) or a chiral smectic H phase (hereinafter abbreviated as S _H ^* phase).
The characteristics of the ferroelectric liquid crystal compound are that it can respond as much as 1000 times faster than the TN type display system by the interaction between spontaneous polarization and applied voltage, and that the display memory can be obtained even when the power is turned off. Development is actively underway.

By the way, the response time τ of the ferroelectric liquid crystal is
Approximately τ = η / P _S E [2] is given by the formula [2] (where η is the viscosity, P _S is the spontaneous polarization, and E is the electric field strength). 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 S _C ^* compounds have a large viscosity and A ferroelectric liquid crystal compound having a substantially large spontaneous polarization and excellent high-speed response can be obtained because the dipoles in the two directions are opposite to each other due to steric factors and cancel out the effect. The current situation is not.

[0005]

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

[0006]

The above-mentioned object can be achieved by an optically active compound represented by the following general formula [1] and a chiral smectic liquid crystal composition containing the compound.

[Chemical 2] [1] (In the formula, R ^{1 *} and R ^{2 *} represent an optically active group having 4 to 20 carbon atoms. N represents an integer of 0 to 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 has R ^{1 *} and R ^{1
2 *} are both optically active groups having 4 to 20 carbon atoms, but an alkyl group having 5 to 16 carbon atoms is preferable from the orientation of liquid crystal molecules, and the position of the asymmetric carbon is directly or directly attached to the ester group. If they are connected via one and their absolute configurations are opposite to each other, the spontaneous polarization is canceled and becomes smaller.
It is preferable that they are the same. Further, it is desirable that the portion excluding the asymmetric carbon be 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 can be seen 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, and by introducing a hydroxyl group at one of the ortho positions. , The chiral smectic liquid crystal composition containing the dipoles, which increase the number of dipoles that induce spontaneous polarization, and have the dipoles fixed in the same direction by intramolecular hydrogen bonds of the hydroxyl group and the carbonyl group. Depending on the product, a liquid crystal element characterized by extremely large spontaneous polarization and high-speed response can be manufactured. The optically active compound of the present invention may be produced by appropriately combining conventionally known methods, and can be achieved by the following synthetic route.

[0009]

[Chemical 13] →

[Chemical 14] ─┐ (II) a (III) │├ →

[Chemical 17] →

[Chemical 18] ─┐│c (VI) d (VII) │

[Chemical 15] →

[Chemical 16] ─┘ ├ →

[Chemical 21] (IV) b (V)
│f (I) │

[Chemical 19] →

[Chemical 20] ────┘ (VIII) e (IX)

That is, a) esterification of paraiodobenzoic acid with an optically active alcohol, b) para-bromophenylboronic acid (or para-bromophenylboronic acid) via a halogen-lithium exchange reaction of para-dibromobenzene (or 4,4'-dibromobiphenyl). 4'-bromobiphenyl-4-boronic acid), c) transition metal-catalyzed coupling reaction of aromatic halogen compound and aromatic boronic acid, d) transition metal-catalyzed substitution of aromatic halogen with trialkyltin, e ) 4
6 steps of esterification of iodosalicylic acid and optically active alcohol, and f) transition metal-catalyzed coupling reaction of aromatic trialkyltin and aromatic halogen. However, when n = 0, the reaction between b) and c) is unnecessary. First, in the reaction of a), as the esterification reaction of the aromatic carboxylic acid represented by the general formula (II) and the optically active alcohol, an acid-catalyzed dehydration reaction or a dehydration condensation agent (eg, dicyclohexylcarbodiimide) is used. , A method in which an aromatic carboxylic acid is converted into an acid chloride with thionyl chloride and then esterified. Among them, a method using a dehydration condensing agent from the viewpoint of the reaction apparatus, the easiness of operation and the reaction yield. Is preferred.

The amount of the dehydration condensing agent used is preferably an equivalent amount to the aromatic carboxylic acid and the optically active alcohol, and about 0.1 times mol of dimethylaminopyridine or 4-pyrrolidinopyridine is used as an activation catalyst. It is more preferable to add. 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. 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 b), 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,
Boron or tin metal is preferable because only one of them is converted to a metal and then a coupling reaction with other aromatic halogen compound is selectively performed. Further, boron or tin metal is more preferable in terms of reaction conditions, stability, reaction yield and the like. preferable.

The metal reagent used is preferably trialkoxyborane. First, a halogen-lithium exchange reaction is carried out with 1.0 times mol of alkyllithium, and then trialkoxyborane is reacted to give parabromophenylboronic acid (or 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 achieved at a reaction temperature of −80 to −70 ° C. for 0.2 to 1.0 hour. Next, the conversion reaction from lithium to boronic acid is initially -80 to-
The method is preferably performed at 70 ° C. and gradually raised to room temperature, and the reaction time is preferably 5 to 24 hours. Then c)
The reaction of b) with the aromatic halide obtained in a)
It is a transition metal-catalyzed coupling reaction with the aromatic boronic acid obtained in. Generally, the halide used for the coupling reaction with the boronic acid may be either bromine or iodine, but in the present invention, since the boronic acid of b) has bromine in the para position, the aromatic halogen of a) is , Iodide having higher reactivity is preferable.

The catalyst used in the reaction is preferably a divalent or zero-valent Pd catalyst, and among them, a zero-valent Pd catalyst such as tetrakis (triphenylphosphine) palladium is used in view of conditions such as reaction time and reaction yield. Is more preferable, and the amount used may be 0.01 to 0.1 times mol. The reaction is carried out in a benzene solution in the presence of a base, and it is more preferable to add a small amount of ethanol because of its solubility in the substrate. The mixing ratio of ethanol to benzene is preferably benzene / ethanol = 20/1 to 10/1, and the basic aqueous solution to be added is preferably sodium carbonate, sodium acetate, sodium hydroxide, or the like. Most preferred. The amount added is 2.0 to 3.0.
A double mole is preferable. The reaction is carried out under reflux, and the reaction time is 1 to 10 hours, more preferably 4 to 10 hours. Next, in the reaction of d), an organometallic compound is synthesized from the aromatic halide obtained in c). As the metal to be used, boron or tin is preferable because it undergoes a coupling reaction with an aromatic halide as in the reaction of c), and the organometallic compound of the present invention has a carboxylic acid ester as a substituent. Therefore, tin is most preferable because it selectively reacts only with bromine or iodine of the aromatic halogen. The metal reagent used is preferably hexaalkylditin, and the amount used is 1.0 to 8.0 times the molar amount of the aromatic carboxylic acid ester.
The amount may be 5 to 3.5 times the molar amount, and may be in the presence of a zero-valent Pd catalyst (0.
03-0.05 times mol). Sufficiently dehydrated toluene is used as a reaction solvent, and the reaction time is 80 to 100 ° C., preferably 90 to 100 ° C., and the reaction time is preferably 2 to 6 hours.

Next, the reaction e) is an esterification reaction of 4-iodosalicylic acid with an optically active alcohol, and a)
It is achieved by the same synthetic method as. However, in the reaction of e), the aromatic carboxylic acid represented by the formula (VIII) has a hydroxyl group at the 2-position, and the esterification reaction between the same molecules also progresses. A method in which alcohol, a dehydration condensing agent, and an activation catalyst are dissolved in a reaction solvent, and finally 4-iodosalicylic acid dissolved in the same solvent is slowly added dropwise is preferable.

Finally, the reaction of f) is a coupling reaction of an aromatic trialkyl tin represented by (VII) with an aromatic halide represented by the formula (IX), and is achieved by using a transition metal catalyst. To be done. The catalyst used is preferably a divalent or zero-valent Pd catalyst or a divalent Ni catalyst. Among them, the divalent Pd catalyst is used depending on the conditions such as reaction time and reaction yield.
The most preferable catalyst is dichlorobis (triphenylphosphine) palladium as the d catalyst, and the amount thereof is 0.01
~ 0.1 times mole is sufficient. The reaction solvent is preferably fully dehydrated tetrahydrofuran or a dehydrated mixed solvent of tetrahydrofuran and hexamethylphosphoric triamide,
From the viewpoint of reaction yield, a mixed solvent of tetrahydrofuran / hexamethylphosphoric triamide = 4/1 is more preferable. The reaction is carried out under reflux, and the reaction time is 1 to 24 hours, more preferably 5 to 24 hours. The products obtained by the reactions a) to f) 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.

[0016]

[Chemical formula 22] (1)

[Chemical formula 23] (2)

[Chemical formula 24] (3)

[Chemical 25] (4)

[Chemical formula 26] (5)

[Chemical 27] (6)

[Chemical 28] (7)

[Chemical 29] (8)

[Chemical 30] (9)

[Chemical 31] (10)

[0017]

[Chemical 32] (11)

[Chemical 33] (12)

[Chemical 34] (13)

[Chemical 35] (14)

[Chemical 36] (15)

[Chemical 37] (16)

[Chemical 38] (17)

[Chemical Formula 39] (18) (However, R represents an alkyl group, and an oxygen atom in parentheses may or may not be present.)

The compounding amount of the compound of the present invention is preferably 3 mol% or more, more 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, and use it. As a result, it is possible to obtain a high-quality operation display and a high-speed response optical switch or optical shutter. The present invention will be specifically described below with reference to examples.

Example 1. [3 "-hydroxy-4"-
(S-(+)-1-methylheptyloxycarbonyl)
Production of 4- (S-(+)-1-methylheptyloxy) paraterphenyl-4-carboxylate]

[Chemical 40] A) Preparation of para-iodobenzoic acid S-(+)-1-methylheptyloxy ester 8.0 g (32.3 mmol) of para-iodobenzoic acid and 4.2 g (32.3 mmol) of S-(+)-2-octanol. Is dissolved in 100 ml of dry tetrahydrofuran,
Furthermore, 0.48 g (3.23 mmol) of 4-pyrrolidinopyridine and 6.65 g of dicyclohexylcarbodiimide.
(32.3 mmol) is added and the mixture is stirred at room temperature overnight. After completion of the reaction, the 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.
6 g (23.9 mmol) were obtained.

[Chemical 41] (Yield 74%)

B) 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 mmol) of n-butyllithium at -78 ° C. After dripping, the mixture is stirred for another hour. Then, after 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 completion of the reaction, ethyl acetate 2
The mixture was extracted with 00 ml, washed with water until neutral, and the solvent was distilled off to obtain 3.7 g (18.4 mmol) of the following compound.

[Chemical 42] (Yield 58%)

C) 4'-Tributyltin biphenyl-4
-Preparation of carboxylic acid S-(+)-1-methylheptyloxy ester 3.0 g (8.3 mmol) of para-iodobenzoic acid S-(+)-1-methylhexyloxy ester synthesized in A) and B) 1.67 g (8.3 mmol) of para-bromophenylboronic acid synthesized in Step 1 was dissolved in a mixed solvent of 105 ml of benzene and 8.5 ml of ethyl alcohol, and an aqueous solution of sodium carbonate 2.2 g (20.8 mmol) 10.4 was added.
ml and tetrakis (triphenylphosphine) palladium 0.29 g (0.25 mmol) were added, and the mixture was heated with stirring under reflux for 10 hours. After completion of the reaction, ethyl acetate 20
It is extracted with 0 ml, washed with water until it becomes neutral, and the solvent is distilled off. The obtained crude product was purified by silica gel column chromatography to give 2.95 g of the following compound.
(7.6 mmol) was obtained.

[Chemical 43] (Yield 91%) 1.17 g (3.0 mmol) of this compound was dissolved in 30 ml of dry toluene to obtain 5.23 g (9.0 mmol) of hexabutylditin and 0.04 g of tetrakis (triphenylphosphine) palladium. (0.0
(3 mmol), and the mixture is heated with stirring at 90 ° C. for 6 hours.
After completion of the reaction, 100 ml of a saturated aqueous solution of potassium fluoride is added, and the mixture is extracted with 200 ml of ethyl acetate. The ethyl acetate layer is washed with water until it becomes neutral, and the solvent is distilled off. The obtained crude product was purified by silica gel column chromatography to obtain 1.08 g (1.8 mmol) of the following compound.

[Chemical 44] (Yield 60%)

D) 4-Iodosalicylic acid S-(+)-1
Preparation of -methylheptyloxy ester 0.74 g (5.7 mmol) of S-(+)-2-octanol, 1.17 g of dicyclohexylcarbodiimide
(5.7 mmol) and 4-pyrrolidinopyridy 0.0
35 g of dry tetrahydrofuran solution of 9 g (0.57 mmol) was prepared, and 4-iodosalicylic acid 1.5
g (5.7 mmol) of a dry tetrahydrofuran solution 1
Slowly add 5 ml and stir 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.
(4.1 mmol) was obtained.

[Chemical formula 45] (Yield 73%)

E) 4'-Tributyltin biphenyl-4
-4'-tributyltin biphenyl-4-synthesized by coupling reaction C) of carboxylic acid S-(+)-1-methylheptyloxy ester and 4-iodosalicylic acid S-(+)-1-methylheptyloxyester
Carboxylic acid S-(+)-1-methylheptyloxy ester 0.72 g (1.2 mmol) and 4-iodosalicylic acid S-(+)-1-methylheptyloxy ester 0.45 g ( 1.2 mmol) was dissolved in a mixed solvent of 20 ml of dry tetrahydrofuran and 5 ml of dry hexamethylphosphoric triamide, and 0.09 g of bis (triphenylphosphine) palladium chloride (0.
(12 mmol), and the mixture is heated with stirring under reflux overnight.
After completion of the reaction, 100 ml of a saturated aqueous solution of potassium fluoride is added, the mixture is extracted with 200 ml of ethyl acetate, washed with water until neutral, and the solvent is distilled off. The obtained crude product was purified by silica gel column chromatography to obtain the following final compound.

[Chemical formula 46] (Yield 63%)

Analytical value: i) ¹ H-NMR (proton nuclear magnetic resonance spectrum CD
Cl ₃ ) δ (ppm) 0.8 to 1.9 (m 32H) 5.2
(M 2H) 7.1-8.2 (m 11H) 11.04
(S 1H) ii) IR (infrared absorption spectrum) ν (cm ⁻¹ ) 3433, 1713, 1669 iii) MS (mass spectrum) m / e 558 (M ⁺ ).

Example 2. [3 "-hydroxy-4"-
(S-(+)-1-methylheptyloxycarbonyl)
Production of 4- (S-(-)-1- (1,1,1-trifluoromethylheptyloxy) paraterphenyl-4-carboxylate]

[Chemical 47] In the same manner as in Example 1 except that 1,1,1-trifluoro-S-(−)-2-octanol was used instead of S-(+)-2-octanol in A) of Example 1. An optically active compound having the following structure was obtained.

[Chemical 48] Analytical value: i) ¹ H-NMR δ (ppm) 0.8 to 2.0 (m 29H) 5.2
(M 1H) 5.6 (m 11H) 7.1 to 8.2 (m
11H) 11.04 (s 1H) ii) IR ν (cm ^-1 ) 3156, 1735, 1670 iii) MS m / e 612 (M ⁺ )

Example 3. [3 "-hydroxy-4"-
(R-(-)-1-methylheptyloxycarbonyl)
Preparation of 4- (R-(+)-1- (1,1,1-trifluoromethylheptyloxy) paraterphenyl-4-carxylate]

[Chemical 49] Instead of S-(+)-2-octanol of A) of Example 1, 1,1,1-trifluoro R-(+)-2-octanol and of S-(+)-2 of D) are used. An optically active compound having the following structure was obtained in the same manner as in Example 1 except that R-(-)-2-octanol was used instead of -octanol.

[Chemical 50] Analytical value: i) ¹ H-NMR δ (ppm) 0.8 to 2.0 (m 29H) 5.2
(M 1H) 5.6 (m 11H) 7.1 to 8.2 (m
11H) 11.04 (s 1H) ii) IR ν (cm ^-1 ) 3156, 1735, 1670 iii) MS m / e 612 (M ⁺ )

Example 4. [3 ′ ″-hydroxy-
Production of 4 "'-(S-(+)-1-methylheptyloxycarbonyl) 4- (S-(+)-1-methylheptyloxy) paratetraphenyl-4-carboxylate]

[Chemical 51] Instead of the paradibromobenzene of example 1 B),
An optically active compound having the following structure was obtained in the same manner as in Example 1 except that 4,4′-dibromobiphenyl was used.

[Chemical 52] Analysis value: i) ¹ H-NMR δ (ppm) 0.8 to 1.9 (m 32 H) 5.2
(M 2H) 7.2 to 8.2 (m 15H) 11.03
(S 1H) ii) IR ν (cm ⁻¹ ) 3424, 1710, 1664 iii) MS m / e 634 (M ⁺ )

Example 5 (Example of Use) The optically active compounds obtained in the above Examples 1 to 4 were converted into the following (XI)
10 mol% is mixed with the racemic liquid crystal compound represented by the formula,
A chiral smectic liquid crystal composition was produced.

[Chemical 53] (X) Then, those liquid crystal compositions are respectively treated with polyimide-
It is injected into a cell that has been subjected to rubbing treatment, and the electric field strength is 4 V / μ
The spontaneous polarization (Ps) and the response time (τ) in the SC ^* phase when a rectangular wave of m was applied were measured. The physical property values of each liquid crystal composition are shown in Table 1.

[0030]

[Table 1] │

[Chemical 54]

Claims (2)

[Claims] 1. A general formula [1]: [1] (wherein 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 a compound represented by the above general formula [1].