JP2949866B2 - Ether-based tricyclic liquid crystal compound, liquid crystal composition using the same, and liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ether-based tricyclic liquid crystal compound useful as an electro-optical display material.

[0002]

2. Description of the Related Art M. Schadt et al. [APPLIED PHYSICS LETTERS 18 ,
127-128 (1971)] or a field effect type cell (field effect mode cell)
GHHeilmeier, etc. [PROCEED
ING OF THE IEEE 56 , 1162-1117 (1968)], a dynamic light scattering type cell (dynamic scattering mode cell) or GH Heilmeier [APPLIED PHYSICSLETTER].
S 13, 91 (1968)] or D el White (DLWhite) etc. [JOURNAL OF APPLIED PHYSICS 45, 47
18 (1974)].

A liquid crystal material used in a field-effect cell, particularly a TN cell, requires various characteristics. One of the important characteristics is a low operating voltage. Generally, lowering the operating voltage of a liquid crystal display cell corresponds to lowering the threshold voltage Vth of the liquid crystal. The threshold voltage Vth of the liquid crystal has the following relationship between the dielectric constant anisotropy Δε and the elastic constant K.

[0004]

(Equation 1)

[0005]

At present, the threshold voltage V
_The following compounds are known as liquid crystal materials for lowering _th .

[0006]

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Wherein R is an alkyl group, X is a halogen,
m and n represent integers. The compound of the above formula (a) has a large Δε and a large effect of lowering V _{th of the} liquid crystal composition,
This compound has the drawback that the response speed is extremely slow, and the current value that significantly affects the durability of the display device is increased.

The compound of the formula (b) and the compound of the formula (c) have a relatively large Δε, but also have an extremely large elastic constant K and a very high viscosity. When this compound is mixed with a TN type liquid crystal composition, the liquid crystal composition becomes There is a problem that the Vth of the object increases and the response speed decreases.

The problem to be solved by the present invention is that
An object of the present invention is to provide a novel nematic liquid crystal compound which, when added to a base liquid crystal generally used as a nematic liquid crystal material, lowers V _th without increasing the current value of the obtained mixed liquid crystal.

[0010]

According to the present invention, there is provided a compound represented by the following general formula (I):

[0011]

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Wherein R represents a straight-chain alkyl group having 1 to 5 carbon atoms, n represents an integer of 1 to 7, and the cyclohexane ring has a trans configuration. .

The compound of the general formula (I) is a novel compound which has solved the above problems. That is, by mixing the compound of the general formula (I) with one or more other types of nematic liquid crystal compounds, it is possible to suppress an increase in current value and a deterioration in response speed while lowering the Vth of the liquid crystal composition. Can be. Therefore, by using the compound of the general formula (I), a high-resistance TN liquid crystal composition having a high upper limit of the temperature range of the nematic phase of the liquid crystal composition and a low Vth can be obtained.

The compound represented by the general formula (I) according to the present invention can be produced according to the following production method.

[0015]

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Wherein R represents a linear alkyl group having 1 to 5 carbon atoms, n represents an integer of 1 to 7, and the cyclohexane ring has a trans configuration. ) Is reacted with magnesium powder in tetrahydrofuran to produce a Grignard reagent as in formula (III). Second step: reacting a compound of formula (III) with a compound of formula (IV) in the presence of palladium chloride to produce a compound of formula (V). Step 3: Compound of formula (V) in dimethylformamide
The compound of the general formula (I) according to the present invention is produced by reacting with cuprous cyanide.

Table 1 shows the phase transition temperatures of the typical compounds of the general formula (I) thus produced.

[0018]

[Table 1]

(In the table, C is a crystal phase, N is a nematic phase,
I represents each isotropic liquid phase. ) General formula according to the present invention
The compound of (I) is a nematic liquid crystal compound having a strong positive dielectric anisotropy, and therefore, for example, a nematic liquid crystal compound having a negative or weak positive dielectric anisotropy or a strong positive dielectric anisotropy Can be used as a material for a dynamic light-scattering display cell in the state of a mixture with another nematic liquid crystal compound having

Representative examples of preferred compounds which can be used by mixing with the compound represented by the general formula (I) are, for example, 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexane Carboxylic acid 4 '
-Substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'- Substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4-substituted 4 "-substituted terphenyl, 4-substituted biphenyl 4'-substituted cyclohexane, 2- (4'-substituted phenyl) 5-substituted pyrimidine and the like can be mentioned.

Table 2 below shows a matrix liquid crystal which is currently widely used as a nematic liquid crystal material having excellent time-division driving characteristics.
The threshold voltage V _th , the rise time τ _r and the measured threshold voltage of a mixed liquid crystal comprising 80% by weight of (A) and 20% by weight of the compound of No. 1 of the general formula (I) shown in Table 1 were measured. response speed fall time tau _d is tau _r = tau _d, a nematic - isotropic liquid phase transition temperature (hereinafter, referred to as N-I point) is obtained posted. For comparison, the parent liquid crystal (A) itself, each mixed liquid crystal comprising 80% by weight of the parent liquid crystal (A) and 20% by weight of a compound represented by the following formula (a) '(b)' or (c) 'are also shown. did. The mother liquid crystal (A) is

[0022]

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Which comprises the formulas (a) ', (b)',
The compound of (c) ′ is

[0024]

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Is a compound represented by the formula:

[0026]

[Table 2]

From the above Table 2, it can be seen that the compound of the formula (b) '
The compound (c) ′ increases the V _th of the base liquid crystal,
It cannot be used for the purpose of lowering the operating voltage of the liquid crystal display device.

Further, the compound of the formula (a) ′ has a V
Although it has the effect of lowering _th , the response speed is remarkably slowed down, which causes a new problem in its use. Threshold voltage V _th and response speed τ _r listed in Table 2
In order to clarify the relationship of = τ _d , these measurement results are shown in FIG.

(1) Mixed liquid crystal composed of 80% by weight of base liquid crystal (A) and 20% by weight of No. 1 compound of the present invention (2) 80% by weight of base liquid crystal (A) and 20% by weight of comparative compound (a) (3) 80% by weight of the base liquid crystal (A) and 20% by weight of the comparative compound (b) (4) 80% by weight of the base liquid crystal (A) and 20% by weight of the comparative compound (c) (5) Base liquid crystal (A) From FIG. 1, it can be seen that the compound of the general formula (I) according to the present invention has excellent characteristics of lowering V _th without deteriorating the response speed. Is evident.

Conventionally, compounds having the property of lowering V _th are known to increase current value.
However, the compound of the general formula (I) according to the present invention is also excellent in this respect, and the following experiment was performed to explain this.

The base liquid crystal (A) has the No. of formula (I) shown in Table 1
10, 20, and 30% by weight of the compound No. 1 were mixed, and the threshold voltage _{Vth of the} mixed liquid crystal and the specific resistance after a deterioration test by irradiation with ultraviolet rays were measured. For comparison, a similar experiment was performed on the compound of the formula (a) ′, which was found to have an effect of lowering V _th of the parent liquid crystal (A). The result is shown in FIG.

(1) Mixed liquid crystal containing base liquid crystal (A) and compound No. 1 of the present invention (2) Mixed liquid crystal containing base liquid crystal (A) and comparative compound (a) ′ From FIG. The compound of the formula (a) 'lowers the resistance of the mixed liquid crystal, so that its use requires a restriction or special measures. However, the general formula (I) according to the present invention
The compound of (1) has an excellent property that the threshold voltage can be designed without increasing the current value by timely mixing with a liquid crystal display material suitable for the intended use without lowering the resistance value of the mixed liquid crystal. have.

[0033]

EXAMPLES Examples of the present invention are shown below to further explain the present invention. However, the invention is not limited to these examples. (Example 1) 3.2 g (0.13 mol) of magnesium powder and a small amount of 1,2-dibromoethane were added to 20 ml of dry tetrahydrofuran and activated by stirring. Then, below 25 ° C,

[0034]

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A solution of the above compound (33 g, 0.13 mol) in dry tetrahydrofuran (200 ml) was added dropwise, followed by reaction at room temperature for 1 hour. The palladium chloride was then added to the reaction mixture.
0.3g and formula

[0036]

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A solution of the compound (35.8 g, 0.1 mol) in dry tetrahydrofuran (200 ml) was added, and the mixture was heated under reflux for 8 hours. After completion of the reaction, the reaction solution was poured into a mixture of 300 ml of 9% hydrochloric acid and 200 g of ice, extracted twice with 300 ml of ethyl acetate, and the extract was washed with water and dried, and the solvent was distilled off under reduced pressure. The obtained residue was recrystallized from ethanol and purified to obtain the following compound 3
2.3 g (0.08 mol) were obtained.

[0038]

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32.3 g (0.08 mol) of the above compound was dissolved in 250 ml of dimethylformamide, and 7.92 g of cuprous cyanide was dissolved.
(0.088 mol) and heated under reflux for 10 hours. After completion of the reaction, the reaction solution was poured into a mixed solution of 300 ml of aqueous ammonia and 300 g of ice, stirred for 30 minutes, and then the solvent was distilled off under reduced pressure.

The obtained residue was purified by recrystallization from ethanol to obtain 21.8 g (0.062 mol) of the following compound.

[0041]

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[0042]

According to the present invention, the compound represented by the general formula (I) according to the present invention is mixed with a base liquid crystal which is currently widely used as a nematic liquid crystal material, so that the threshold voltage is low, the resistance is high, and the response is fast. A nematic liquid crystal composition exhibiting properties can be prepared.

The effect of the compound represented by the general formula (I) is remarkable as compared with a known compound having a similar structure.
This is extremely useful as a material for producing a TN-type liquid crystal display cell which has excellent visual characteristics and response characteristics and can be driven at a low voltage.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the compound No. of the general formula (I) according to the present invention.
1.A chart showing the relationship between V _th and response time τ _r = τ _{d of} each mixed liquid crystal obtained by mixing a comparative compound (a) ′, (b) ′ or (c) ′ with a base liquid crystal (A). is there.

[Explanation of symbols]

1. Mixed liquid crystal consisting of 80% by weight of base liquid crystal (A) and 20% by weight of the No. 1 compound of the present invention 2. Mixed liquid crystal consisting of 80% by weight of base liquid crystal (A) and 20% by weight of comparative compound (a) 3. Base Mixed liquid crystal composed of 80% by weight of liquid crystal (A) and 20% by weight of comparative compound (b) 4 Mixed liquid crystal composed of 80% by weight of parent liquid crystal (A) and 20% by weight of comparative compound (c) 5 Base liquid crystal (A)

FIG. 2 shows a compound No. of the general formula (I) according to the present invention.
The threshold voltage V _th of each mixed liquid crystal obtained by mixing 1, 20, or 30% by weight of 1, or the comparative compound (a) ′ with the base liquid crystal (A)
6 is a table showing a relationship between the resistance and a specific resistance after a deterioration test by ultraviolet irradiation.

[Explanation of symbols]

1. Mixed liquid crystal containing base liquid crystal (A) and No. 1 compound of the present invention 2. Mixed liquid crystal containing base liquid crystal (A) and comparative compound (a) ′

Claims (3)

(57) [Claims] 1. A compound of the general formula (I) (Wherein R represents a linear alkyl group having 1 to 5 carbon atoms, n represents an integer of 1 to 7, and the cyclohexane ring has a trans configuration). 2. The compound represented by the general formula (I) according to claim 1.
The liquid crystal composition characterized by containing a compound. 3. Use of the liquid crystal composition according to claim 2.
A liquid crystal display device characterized by the above-mentioned.