JPH09309864A - Optically active compound, antiferroelectric liquid crystal composition and liquid crystal element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new optically active compound, capable of driving a liquid crystal at a low voltage and useful as an antiferroelectric liquid crystal composition useful for producing an excellent liquid crystal display element. SOLUTION: This new optically active compound is represented by formula I [(m) is 6-14; (n) is 2-10; X is O, COO or a single bond; * indicates asymmetric carbon], e.g. 1-trifluoromethyl-n-heptyl (R)-6-(4'-decyloxy)benzoyloxy-2- naphthalenecarboxylate represented by formula II. The compound represented by formula I is obtained by esterifying 6-hydroxy-2-naphthalenecarboxylic acid with an optically active alcohol under acidic conditions and then carrying out the esterification of the resultant compound with an alkylbenzoic acid. A liquid crystal compound represented by formula III (R1 is an alkyl, an alkoxy, etc.; R2 is a hydrocarbon; R3 is CH3 or CF3 ) having an antiferroelectric phase may be used in combination with the compound represented by formula I. The compound represented by formula I is preferably blended in an amount of about 5-20wt.% in the liquid crystal composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optically active compound, a liquid crystal composition, particularly an antiferroelectric phase (chiral smectic CA).
^* Phase, or S _mcA ^* phase) and a liquid crystal display device using the composition, more specifically, an optically active naphthalene derivative suitable for use in the liquid crystal display device. The present invention also relates to an antiferroelectric liquid crystal composition containing a compound containing the same, and a liquid crystal display device using the composition.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays are thin, lightweight,
Although it has come to be widely used as a display element by taking advantage of features such as low power consumption, most of these display devices use TN (Twisted) that uses nematic liquid crystal.
d Nematic) type is generally adopted. In this TN type display method, since the driving is based on the anisotropy of the relative dielectric constant of the liquid crystal, the response speed thereof is slow, and there is an urgent need for improvement.

On the other hand, a liquid crystal device using a liquid crystal having a ferroelectric phase (also referred to as a chiral smectic C ^* phase or S _mc ^* phase) found by Meyer et al. responsiveness·
It has a memory property, and taking advantage of these characteristics, application research for ferroelectric liquid crystal displays is being energetically carried out. However, it is difficult to realize the good orientation and memory properties required for this display method in an actual display, and there are problems such as being vulnerable to external shock, and there are many problems to be solved. Remaining.

On the other hand, recently, Chandani et al. Discovered an antiferroelectric phase (S _mcA ^* phase) _{exhibiting a tristable} state on the low temperature side of the ferroelectric phase ( _Japane ).
seJournal of Applied Phys
ics, Vol 27, No. 5, 1988, pp. L7
29). This antiferroelectric phase shows a thermodynamically stable phase in which dipoles are arranged antiparallel to each adjacent layer, and has a clear threshold value and double hysteresis characteristic with respect to the applied voltage. An electric field-induced phase transition between the antiferroelectric phase and the ferroelectric phase occurs. Application of this switching behavior has begun to study new display methods (antiferroelectric liquid crystal displays, etc.).

[0005] Liquid crystal compounds having an antiferroelectric phase include:
JP-A-1-213390, JP-A-1-316339, JP-A-1-3166767, JP-A-2-28128 and the like are already known, and new antiferroelectric liquid crystal compounds have been announced, and gradually. The number is increasing. By the way, most of the antiferroelectric liquid crystal compounds manufactured to date have, for example, a high melting point and a temperature range exhibiting an antiferroelectric phase is much higher than room temperature when considered from a practical viewpoint. Therefore, it is difficult to fabricate a liquid crystal device using only one type of antiferroelectric liquid crystal compound, and usually several or more antiferroelectric liquid crystal compounds are mixed in order to optimize practical physical properties. I am using it.

As such an antiferroelectric liquid crystal composition, for example, in Japanese Patent Laid-Open No. 184536/1994, an antiferroelectric liquid crystal substance composed of a ferrielectric liquid crystal substance and an antiferroelectric liquid crystal substance having a reduced threshold voltage is used. A ferroelectric liquid crystal composition is disclosed,
Japanese Unexamined Patent Publication (Kokai) No. 5-271658 discloses an antiferroelectric liquid crystal composition having a reduced threshold voltage, which is composed of a compound that does not exhibit an antiferroelectric phase and a compound that exhibits an antiferroelectric phase.

Further, Japanese Patent Application Laid-Open No. 3-197445 shows that some compounds represented by the general formula in the composition of the present invention have a liquid crystal phase. However, the compounds show a change in threshold voltage. There is no disclosure or suggestion of what to bring. Japanese Patent Application Laid-Open No. 5-271658 aims to develop an antiferroelectric liquid crystal composition having a reduced threshold voltage, which is composed of a compound that does not exhibit an antiferroelectric phase and a compound that exhibits an antiferroelectric phase. However, the present invention was made based on the finding that some of them have an antiferroelectric phase and can effectively work in reducing the threshold voltage.

[0008]

When applying the switching characteristics of the antiferroelectric phase to a liquid crystal display, it is not impossible to produce a liquid crystal element using a composition consisting of an antiferroelectric liquid crystal alone, Temperature range showing three stable states,
It is not always preferable in terms of liquid crystal drive voltage, crystallization temperature, orientation and the like. In particular, regarding the liquid crystal drive voltage, the current antiferroelectric liquid crystal composition has a high threshold voltage, so that the drive voltage is as high as 35 to 45 V, and due to constraints such as power consumption and withstand voltage conditions of the drive IC It is necessary to reduce the drive voltage. The present invention, in view of such a situation,
By adding the compound of the antiferroelectric liquid crystal to the antiferroelectric liquid crystal composition, without adversely affecting the response time,
It is an object of the present invention to provide an antiferroelectric liquid crystal composition that lowers the threshold voltage and enables low voltage driving, a compound suitable for the antiferroelectric liquid crystal composition, and a liquid crystal display device using such a composition.

[0009]

The present invention uses the novel optically active compound according to claim 1, the antiferroelectric liquid crystal composition according to claim 2 containing the compound, and the composition. It is a liquid crystal display element. By using this composition, the liquid crystal can be driven at a low voltage, and an excellent liquid crystal display device can be manufactured.

As the compound represented by the formula (I), for example, m = 6,7,8,9,10,11,12, n = 4.
Any combination of 5, 6, 7, and 8 can be mentioned. For example, there are cases where m = 6 and n = 4. Also in the composition described in claim 2, the same examples as the above can be mentioned as the compound represented by the general formula (I).

In the composition according to claim 2, the compounding amount of the compound represented by formula (I) is preferably 1 to 30% by weight, more preferably 5 to 20% by weight based on the whole liquid crystal composition. % By weight. Here, if the blending amount is less than 1% by weight, the effect of lowering the threshold voltage described later is small, and if the blending amount is more than 30% by weight, the temperature range of the antiferroelectric phase is extremely reduced. Not preferable.

Further, an antiferroelectric liquid crystal compound or composition for blending the compound represented by the general formula (I) is
Any known antiferroelectric liquid crystal compound or a mixture thereof may be used. For example, the following general formula (II) (in the formula, R ₁ represents an alkyl group having 6 to 14 carbon atoms, an alkoxy group, or an alkylcarbonyloxy group, R 1
₂ may partially contain an oxygen atom such as an ether group or a carbonyl group. R ₃ is CH ₃ or CF
₃ is shown. Each aromatic ring may be substituted with a halogen atom or a methyl group. Any of the compounds represented by () may be used as long as they have an antiferroelectric phase.

[0013]

Embedded image

[General Synthetic Method] The synthetic method of the compound represented by the general formula (I) is described below.

[0015]

Embedded image

A commercially available 6-hydroxy-2-naphthalenecarboxylic acid and an optically active alcohol are esterified under acidic conditions, and then esterified with an alkylbenzoic acid to obtain a desired product.

[0017]

[Chemical 6]

In the above reaction formula, R'is C ^* H (C
F ₃₎ shows a C _n H _{2n + 1,} R represents a C _m H _{2m +1} -X. In Reaction 1, esterification is carried out using H ₂ SO ₄ .
In reaction 2, esterification is carried out using DCC.

[0019]

The present invention will be described more specifically with reference to the following examples. In addition, the identification of the compounds in the examples is carried out by NM
R, IR, and optical rotation were measured, and phase transition temperature measurement and phase identification were carried out by DSC and polarization microscope observation.

Example 1 (Synthesis of (R) -6- (4'-decyloxy) benzoyloxy-2-naphthalenecarboxylic acid 1-trifluoromethyl-n-heptyl ester)

[0021]

[Chemical 7]

The title compound was prepared according to the following steps.
0.71 g of 4'-decyloxybenzoic acid, (R) -6-
(1-trifluoromethylheptyloxycarbonyl-
After dissolving 0.88 g of 2-naphthol and 0.02 g of 4-dimethylaminopyridine in 15.0 ml of methylene chloride at room temperature, 0.63 g of dicyclohexylcarbodiimide
Was added and the mixture was stirred overnight at room temperature. After completion of the reaction, the precipitated impurities were filtered off and extracted with methylene chloride. The organic layer was washed with a 3% aqueous hydrochloric acid solution, water, and saturated saline, and then dried over anhydrous magnesium sulfate. After the desiccant was filtered off, the solvent was distilled off. The obtained composition organism was purified by silica gel column chromatography and recrystallization with ethanol to obtain 1.22 g of the desired product.

¹ H-NMR spectrum (CDCl _3, pp
m): 0.85-0.91 (m, 6H), 1.20-1.
50 (m, 22H), 1.81-1.85 (m, 2
H), 1.90-1.94 (m, 2H), 4.06
(T, 2H), 5.59-5.64 (m, 1H), 6.
99 (d, 2H), 7.45 (d, 2H), 7.75
(S, 1H), 7.89 (d, 2H), 8.03 (d,
2H), 8.09 (d, 2H), 8.18 (d, 2)
H), 8.66 (s, 1H). IR spectrum (KBr disc, cm ^-1 ): 2924,
2856, 1732, 1609, 1260, 1189,
1171, 1096, 723. Specific rotation [α] _D ²⁰ : 43.72 (C, 2.095,
in CHCl ₃ ).

Example 2 (Synthesis of (R) -6- (4'-n-undecanoyloxy) benzoyloxy-2-naphthalenecarboxylic acid 1-trifluoromethyl-n-heptyl ester)

[0025]

Embedded image

The title compound was prepared according to the following steps. Four
-N-undecanoyloxyoxybenzoic acid 0.78
g, (R) -6- (1-trifluoromethyl-n-heptyloxycarbonyl-2-naphthol 0.90 g, 4
-Dimethylaminopyridine 0.02 g with methylene chloride 1
After dissolving in 5.0 ml at room temperature, 0.63 g of dicyclohexylcarbodiimide was added, and the mixture was stirred at room temperature for 24 hours. After completion of the reaction, the precipitated insoluble matter was filtered off and extracted with methylene chloride. The organic layer was washed with a 3% aqueous hydrochloric acid solution, water, and saturated saline, and then dried over anhydrous magnesium sulfate. After the desiccant was filtered off, the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography and recrystallization with ethanol to give the desired product (0.
52 g were obtained.

¹ H-NMR spectrum (CDCl _3, pp
m): 0.85-0.90 (m, 6H), 1.20-1.
50 (m, 22H), 1.76-1.80 (m, 2
H), 1.90-1.95 (m, 2H), 2.60.
(T, 2H), 5.59-5.64 (m, 1H), 7.
27 (d, 2H), 7.45 (d, 1H), 7.76
(S, 1H), 7.90 (d, 1H), 8.05 (d,
1H), 8.10 (d, 1H), 8.27 (d, 2)
H), 8.67 (s, 1H). IR spectrum (KBr disc, cm ^-1 ): 2927,
2855, 1737, 1604, 1262, 1188,
859,746. Specific rotation [α] _D ²⁰ : 40.96 (C, 2.070,
in CHCl ₃ ).

(Example 3) ((R) -6- (4'decyl) benzoyloxy-2-)
Synthesis of naphthalenecarboxylic acid 1-trifluoromethyl-n-heptyl ester)

[0029]

Embedded image

The title compound was prepared according to the following steps. Four
-Decylbenzoic acid 0.67 g, (R) -6- (1-trifluoromethylheptyloxycarbonyl-2-naphthol 0.90 g, 4-dimethylaminopyridine 0.03
g was dissolved in 15.0 ml of methylene chloride at room temperature,
Dicyclohexylcarbodiimide (0.63 g) was added, and the mixture was stirred at room temperature overnight. After completion of the reaction, the precipitated insoluble matter was filtered off and extracted with methylene chloride. The organic layer was washed with a 3% aqueous hydrochloric acid solution, water, and saturated saline, and then dried over anhydrous magnesium sulfate. After the desiccant was filtered off, the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography and recrystallization with ethanol to obtain 1.08 g of the desired product.

¹ H-NMR spectrum (CDCl _3, pp
m): 0.85-0.90 (m, 6H), 1.20-1.
50 (m, 22H), 1.76-1.80 (m, 2
H), 1.90-1.95 (m, 2H), 2.71.
(T, 2H), 5.60-5.63 (m, 1H), 7.
34 (d, 2H), 7.46 (d, 1H), 7.76
(S, 1H), 7.89 (d, 1H), 8.04 (d,
1H), 8.10 (d, 1H), 8.15 (d, 2)
H), 8.66 (s, 1H). IR spectrum (KBr disc, cm ^-1 ): 2923,
2852, 1736, 1630, 1610, 1262,
1189, 765, 747. Specific rotation [α] _D ²⁰ : 45.07 (C, 2.070,
in CHCl ₃ ).

Example 4 A liquid crystal composition was prepared.
The antiferroelectric liquid crystal compounds III-1 to III-
4 (all R bodies) were mixed to prepare a reference liquid crystal. The composition ratio at that time is shown in Table 1.

[0033]

Embedded image

[0034]

[Table 1]

The compounds shown in Examples 1, 2 and 3 were added to this reference liquid crystal so as to make up 20% by weight of the total composition, to prepare compositions A, B and C. However,
In the present invention, the same effect can be obtained by mixing two or more compounds represented by formula (I), and the present invention is not limited to the examples.

Next, the threshold voltage was measured. Each liquid crystal composition was injected into a liquid crystal cell (gap: 2 μm) that was subjected to an alignment treatment by rubbing. After injection, heat the cell to a temperature at which the liquid crystal composition changes to an isotropic liquid,
Then, it was cooled to room temperature at 2 ° C./min to obtain an antiferroelectric liquid crystal element. A 1 Hz triangular wave as shown in FIG. 1 was applied to this device, and the transmitted light intensity was measured under a crossed Nicols using a polarization microscope. Thereby, a voltage-transmitted light intensity correlation diagram as shown in FIG. 2 was obtained. In the double hysteresis shown in FIG. 2, the liquid crystal drive voltage at which the relative transmittance becomes 90% when the voltage is increased is set as a threshold voltage, and this value is obtained.

Next, the response time was measured. The response time, which greatly affects the display characteristics, is
An electric field of 5 V / μm was applied and measurement was performed as shown in FIG. The results of the response time of the composition are shown in Table 2. As is clear from Table 2, the threshold voltage was 1 at 50 ° C. by adding the compound synthesized in Reference Example to the antiferroelectric composition.
It could be reduced by 2 to 23%.

[0038]

[Table 2]

By adding the compound of the present invention to the reference liquid crystal, the threshold voltage of the liquid crystal composition can be significantly reduced as compared with the reference liquid crystal without lowering the response time.

[Brief description of drawings]

FIG. 1 is a graph showing a triangular wave voltage used in Example 1.

FIG. 2 is a graph showing the correlation between voltage and transmitted light intensity obtained in Example 1.

FIG. 3 is a graph showing a method for measuring a response time of liquid crystal used in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Inada 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute (72) Inventor Hitoshi Suenaga 5-41 Senmon, Itami-shi, Hyogo Teikoku Kagaku Sangyo Co., Ltd. (72) Inventor Katsuaki Takahashi 5-41 Senmon, Itami-shi, Hyogo Teikoku Kagaku Sangyo Co., Ltd. (72) Inventor Yoshiro Okuda 5-41 Senmon, Itami-shi, Hyogo Teikoku Kagaku Sangyo Co., Ltd.

Claims (4)

[Claims] 1. A compound represented by the following general formula (I) (Here, m represents an integer of 6 to 14, n represents an integer of 2 to 10, and X represents -O-, -COO-, or a single bond. * Represents an asymmetric carbon.) An optically active compound represented by. 2. The following general formula (I): (Here, m shows the integer of 6-14, n shows the integer of 2-10. Moreover, X shows -O-, -COO-, or a single bond. * Shows an asymmetric carbon. ) An antiferroelectric liquid crystal composition comprising at least one compound represented by the formula (1) and at least one compound having an antiferroelectric phase (S _mcA ^* phase). 3. At least one compound represented by the general formula (I) according to claim 1 and at least a liquid crystal compound represented by the following general formula (II) having an antiferroelectric phase. An antiferroelectric liquid crystal composition comprising one kind. Embedded image However, R ₁ represents an alkyl group having 6 to 14 carbon atoms, an alkoxy group, or an alkylcarbonyloxy group, and R ₂ contains an oxygen atom such as an ether group or a carbonyl group in a part thereof. 2-10 carbon atoms that can be used
Represents a hydrocarbon group. R ₃ represents CH ₃ or CF ₃ . 4. A liquid crystal display device using the antiferroelectric liquid crystal composition according to claim 2.