JPH04290859A - Cyclohexylterphenyl derivative, liquid crystal composition containing the same and liquid crystal display element produced by using the composition - Google Patents

Abstract

PURPOSE:To provide the subject compound useful as a basic component of a liquid crystal composition having broad practical temperature range and low threshold voltage, especially a composition for TN or STN-type liquid crystal display. CONSTITUTION:The compound of formula I (R is 1-10C alkyl; X is H or F; the configuration of the cyclohexane ring is trans), e.g. 4-(trans-4- pentylcyclohexyl)-3''-fluoro-4''-cyanoterphenyl. The compound of formula I can be produced by reacting a compound of formula II with a compound of formula III in a mixture of ethanol and benzene in the presence of tetrakistriphenylphosphine palladium. The compound is compounded to a liquid crystal composition in an amount of 1-50wt.%, preferably 3-30wt.%. The liquid crystal display device containing the compound can be used in watch, electronic calculator, audio system, various instruments, automobile dash-board, display, color TV, etc.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The present invention relates to a novel cyclohexylterphenyl derivative used as an electro-optical display material, a liquid crystal composition containing the same, and a liquid crystal display element using the same.

0002

2. Description of the Related Art Liquid crystal display devices utilize the electro-optic effect of liquid crystals, and liquid crystal phases used therein include nematic, cholesteric, and smectic phases. Currently, the most widely used display method is twisted nematic (hereinafter referred to as TN), which uses a nematic phase.
It is a type.

[0003]The liquid crystal display device is 1. Can be made small and thin.

2. Low driving voltage and low power consumption.

3. Since it is a light receiving element, the eyes will not get tired even if it is used for a long time.

[0006] Because of these advantages, it has been applied to watches, calculators, audio equipment, various measuring instruments, automobile dashboards, etc. Particularly recently, it has been applied to displays with a large number of pixels, such as personal computers and word processors, as well as color televisions, and is attracting attention as a display device that can replace CRTs. As described above, liquid crystal display devices are being applied in many fields, and it is thought that the fields of application will further expand in the future. Along with this, the characteristics required of liquid crystal materials are expected to change, but the characteristics shown below are basic and indispensable. 1. No coloring, heat, light,
Must be electrically and chemically stable.

2. Wide practical temperature range.

3. Fast electro-optical response speed.

4. Low driving voltage.

5. The voltage-light transmittance characteristic has a steep rise, and its threshold voltage (hereinafter referred to as Vth)
temperature dependence is small.

6. Wide viewing angle range.

0012

[Problems to be Solved by the Invention] However, although many liquid crystals are known that satisfy property 1 of these properties, no liquid crystal compound is known that satisfies property 2 or less with a single component. Therefore, in order to obtain these characteristics, a liquid crystal composition in which several types of nematic liquid crystal compounds or non-liquid crystal compounds are mixed is used. In order to satisfy characteristic 4 of these, the threshold voltage must be lowered, but the difference between Vth, elastic constant (hereinafter referred to as K), and dielectric constant anisotropy (hereinafter referred to as Δε) has the following relational expression, and in order to lower Vth, Vth∝(K/Δε)1/2, a liquid crystal compound with a large Δε and a small K is required. However, there are almost no liquid crystal compounds that satisfy properties 2 and 4 at the same time, and a composition that is a combination of a compound having properties 2 and a liquid crystal compound having properties 4 is generally used.

[0013] The present invention has been developed to meet the needs of the above-mentioned situation, and its purpose is to create a liquid crystal composition that has a wide practical temperature range and a low threshold voltage by mixing it with several types of nematic liquid crystal compounds or non-liquid crystal compounds. The object of the present invention is to provide a novel liquid crystal compound from which liquid crystals can be obtained.

[0014]

[Means for Solving the Problems] The present invention is based on the general formula

001
5]

[C6]

(In the above formula, R represents a straight chain alkyl group having 1 to 10 carbon atoms, X represents hydrogen or fluorine, and the cyclohexane ring has a trans configuration.) A cyclohexylterphenyl derivative, a liquid crystal composition containing the same, and a liquid crystal display element using the same. The compound (1) of the present invention can be obtained by the following production method.

[0017]

[Table 1]

Step 1) Compound (2) is reacted with bromine in carbon tetrachloride in the presence of iodine to obtain compound (3).

Step 2) Compound (3) is converted into a Grignard reagent in tetrahydrofuran and reacted with triisopropyl borate to obtain compound (4).

Step 3) Compound (5) is reacted with bromine in chloroform in the presence of pyridine to obtain compound (6).

Step 4) Compound (6) or (7) is reacted with sodium nitrite and sulfuric acid in acetic acid to form a diazonium salt, and then reacted with copper sulfate and potassium cyanide to obtain compound (8).

Step 5) Compound (4) and compound (8) are reacted in a mixed solvent of ethanol and benzene in the presence of tetrakistriphenylphosphine palladium to obtain compound (1).

Components of the base liquid crystal composition when the cyclohexylterphenyl derivative of the present invention is mixed include the following compounds, but are not limited to these, and include all conventional liquid crystal compounds or It has good compatibility with similar compounds, and the obtained liquid crystal composition has a wide practical temperature range and a low threshold voltage.

[0024]

[Table 2]

(Here, R and R' represent an alkyl group, an alkoxy group, an alkoxymethylene group, a nitrile group, or a fluoro group, and the phenylene group may have a halogen substituent at the 2 or 3 position, and the cyclohexane ring is a trans configuration.) Furthermore, the proportion of the compound of the present invention that can be mixed into this liquid crystal composition is 1 to 50% by weight, but when considering crystal precipitation in a low temperature region, it is 3 to 30% by weight. The range is particularly preferred.

A liquid crystal display device using a liquid crystal composition containing at least one compound of the present invention is suitable for a liquid crystal display device using a time-division driving method, and is particularly suitable for TN type and S type liquid crystal display devices.
High time division driving is possible in a TN type liquid crystal display element.

[0027]

[Examples] The present invention will be explained in more detail with reference to Examples below.

(Example 1) [Synthesis of compound (1-a)]
4-(trans-4”'-pentylcyclohexyl)-
Production process of 3”-fluoro-4”-cyanoterphenyl 1) Put 100 g of 4-(trans-4”-pentylcyclohexyl)biphenyl into a flask and add 490 g of carbon tetrachloride.
ml and added 2 g of iodine. This solution was cooled to below 5°C in an ice-water bath, and 66m of carbon tetrachloride was added to the solution.
A solution dissolved in 1 ml was added dropwise. The mixture was stirred as it was for 2 hours at 5°C or lower, and then at 40 to 50°C for 2 hours. After the reaction was completed, it was washed three times with hot water, twice with a 10% aqueous potassium hydroxide solution, and three times with hot water. Carbon tetrachloride was distilled off, the residue was recrystallized from a mixed solvent of chloroform and acetone, and 4-
72 g of (trans-4''-pentylcyclohexyl)-4-bromobiphenyl was obtained.

Step 2) In a nitrogen atmosphere, put 3.7 g of magnesium into a flask, and add 50 g of tetrahydrofuran there.
A solution of 52 g of 4-(trans-4"-pentylcyclohexyl)-4-bromobiphenyl was added dropwise to the 0 ml. After the addition was completed, the solution was stirred at room temperature overnight to prepare a Grignard reagent. 50 g of triisopropyl borate was added to 15 ml of tetrahydrofuran. Grignard reagent was added dropwise into the solution at room temperature. After the addition, the mixture was stirred overnight at room temperature. Then, 100 ml of 10% hydrochloric acid was added and stirred for 1 hour. After extraction with chloroform, the mixture was washed three times with water and the chloroform was removed. The resulting residue was recrystallized from a mixed solvent of methanol and acetone to obtain 21 g of 4-(trans-4''-pentylcyclohexyl)-4-biphenylboric acid.

Step 4) Dissolve 16.4 g of sodium nitrite in 125 ml of sulfuric acid, cool to below 10°C, and then dissolve 16.4 g of sodium nitrite in 125 ml of sulfuric acid.
Add 43 ml of 4-bromo-2 at 20-25°C.
- 40 g of fluoroaniline was added and then stirred for 1 hour. 50.5 g of copper sulfate pentahydrate was dissolved in 125 ml of water, and 85 g of ice was placed therein. Furthermore, a solution of 53 g of potassium cyanide dissolved in 125 ml of water, 303 g of sodium bicarbonate, and 125 ml of benzene were added. A diazonium salt sulfuric acid solution was added thereto. After stirring at room temperature for 3 hours, an aqueous sodium hydroxide solution was added to dissolve the crystals. After extraction with chloroform, 10% aqueous sodium hydroxide solution,
Each was washed three times with water. After distilling off the chloroform, the residue was distilled under reduced pressure (105-110°C/14mmHg),
Furthermore, recrystallization was performed from hexane, and 4-bromo-2-
16 g of fluorobenzonitrile was obtained.

Step 5) In a nitrogen atmosphere, 4-bromo-2-
2.7 g of fluorobenzonitrile, 0.5 g of tetrakistriphenylphosphine palladium, 20 m of benzene
l, into a mixture of 15 ml of 2M aqueous sodium carbonate solution,
4-(trans-4”-pentylcyclohexyl)-4
- A solution of 4 g of biphenylboric acid dissolved in a mixed solvent of 67 ml of ethanol and 130 ml of benzene was dropped at room temperature. After refluxing for 5 hours, the reaction solution was cooled to room temperature, extracted with chloroform, washed with water three times, and chloroform was distilled off. The obtained residue was recrystallized from a mixed solvent of chloroform and acetone to obtain 2.5 g of 4-(trans-4''-pentylcyclohexyl)-3''-fluoro-4''-cyanoterphenyl. The crystal phase-nematic liquid crystal phase transition point (hereinafter referred to as C-N point) of the compound is 100.
6°C, and the nematic liquid crystal phase-isotropic liquid transition point (hereinafter referred to as NI point) was 345.9°C.

The following compounds were synthesized in a similar manner.

4-(trans-4''-methylcyclohexyl)-3''-fluoro-4''-cyanoterphenyl 4-(trans-4''-ethylcyclohexyl)-3
"-Fluoro-4"-cyanoterphenyl 4-(trans-4"'-propylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'
-butylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'-hexylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'-heptyl tylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'-octylcyclohexyl)-
3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'-nonylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl 4-(trans-4"'
-decylcyclohexyl)-3"-fluoro-4"-cyanoterphenyl (Example 2) [Synthesis of compound (1-b)] 4-(trans-4"'-pentylcyclohexyl)-3",5"- Manufacturing steps 1 and 2) of difluoro-4''-cyanoterphenyl are the same as in Example 1.

Step 3) 78 g of pyridine and 116 g of 2,6-difluoroaniline were dissolved in 450 ml of chloroform and cooled to -10 to -5°C. 150g of bromine into it
A mixed solution of 220 ml of chloroform was added dropwise. Thereafter, the mixture was brought to room temperature and stirred for 3 hours. The reaction solution was washed twice with water, twice with a 10% aqueous potassium hydroxide solution, and further washed twice with water, and then chloroform was distilled off. The residue was distilled under reduced pressure (110-13
0°C/30mmHg), and then recrystallized from a mixed solvent of chloroform and hexane to obtain 4-bromo-2,6
-140 g of difluoroaniline was obtained. Step 4) Dissolve 54g of sodium nitrite in 400ml of sulfuric acid and heat at 10°C.
After cooling, 470 ml of acetic acid was added, and 140 ml of 4-bromo-2,6-difluoroaniline was added at 20 to 25°C.
g was added thereto, and the mixture was stirred for 1 hour. Copper sulfate pentahydrate 16
5g was dissolved in 400ml of water, and 280g of ice was placed therein. Additionally, 174g of potassium cyanide in 200ml of water.
, 990 g of sodium hydrogen carbonate, and 400 ml of benzene were added. A diazonium salt sulfuric acid solution was added thereto. After stirring at room temperature for 3 hours, an aqueous sodium hydroxide solution was added to dissolve the crystals. After extraction with chloroform,
It was washed three times each with a 10% aqueous sodium hydroxide solution and water. After distilling off the chloroform, the residue was distilled under reduced pressure (105
~110° C./15 mmHg) and further recrystallized from hexane to obtain 52 g of 4-bromo-2,6-difluorobenzonitrile.

Step 5) In a nitrogen atmosphere, 4-bromo-2,
Into a mixture of 4.5 g of 6-difluorobenzonitrile, 0.7 g of tetrakistriphenylphosphine palladium, 30 ml of benzene, and 23 ml of a 2M aqueous sodium carbonate solution, 6 g of 4-(trans-4''-pentylcyclohexyl)-4-biphenylborate was added. 100ml of ethanol
A solution prepared by dissolving 200 ml of benzene in a mixed solvent was dropped at room temperature. After refluxing for 5 hours, the reaction solution was cooled to room temperature, extracted with chloroform, washed with water three times, and chloroform was distilled off. The obtained residue was recrystallized from a mixed solvent of chloroform and acetone to give 4-(trans-4'''
5.9 g of -pentylcyclohexyl)-3",5"-difluoro-4"-cyanoterphenyl was obtained. The C-N point of this compound was 124.1°C, and the N-I point was 302
．． It was 0℃.

The following compounds were synthesized in a similar manner.

4-(trans-4''-methylcyclohexyl)-3'',4''-difluoro-4''-cyanoterphenyl 4-(trans-4''-ethylcyclohexyl)-3
",4"-difluoro-4"-cyanoterphenyl 4-
(trans-4”'-propylcyclohexyl)-3”
, 4”-difluoro-4”-cyanoterphenyl 4-(
trans-4"'-butylcyclohexyl)-3",4
"-difluoro-4"-cyanoterphenyl 4-(trans-4"'-hexylcyclohexyl)-3",4"
-difluoro-4"-cyanoterphenyl 4-(trans-4"'-heptyltylcyclohexyl)-3",4
"-difluoro-4"-cyanoterphenyl 4-(trans-4"'-octylcyclohexyl)-3",4"
-difluoro-4"-cyanoterphenyl 4-(trans-4"'-nonylcyclohexyl)-3",4"-difluoro-4"-cyanoterphenyl 4-(trans-
4''-decylcyclohexyl)-3''4,''-difluoro-4''-cyanoterphenyl (Example 3) [Liquid crystal composition] Commercially available mixed liquid crystal ZLI-1565 (Merck product, N-
The base liquid crystal is 4-pentyl, which is currently used for the purpose of lowering the threshold voltage.
A liquid crystal composition of 4''-cyanoterphenyl and 4-(trans-4''-pentylcyclohexyl)-3''-fluoro-4''-cyanoterphenyl of Example 1, which is a compound of the present invention, was prepared.

[0038]

[Table 3]

The N-I point and birefringence (hereinafter referred to as Δn) of compositions a and b were measured. The results are as follows.

[0040]

[Table 4]

(Example 4) [Liquid crystal display element] As shown in FIG. 1, transparent electrode films (for example, I
An electrode 3 made of (TO film) is formed, and an alignment film made of polyimide or the like is applied thereon. Next, the alignment control layer 4 is formed by rubbing, and the glass substrates 1 and 2 are placed facing each other with a sealant 6 in between, and the liquid crystal compositions a and b prepared in Example 3 are injected between the glass substrates, respectively. Substrates 1 and 2
TN type liquid crystal display cells A and B were prepared by pasting a polarizing plate on the outer surface of the cell. Note that the cell gap was 8 μm.

The thus produced liquid crystal display cell was subjected to AC static driving to determine the voltage-light transmittance viewing angle dependence (hereinafter referred to as α), steepness (hereinafter referred to as β), and
Vth was measured. Note that α, β, Vth, and Vsat were defined by the following equations.

[0043]

[Math 1]

The results of the measurement were as follows.

[0045]

[Table 5]

In the above embodiments, a TN type liquid crystal display cell was used, but similar effects were obtained when an STN type display cell was used.

[0047]

As described above, when the compound of the present invention is mixed into a general liquid crystal mixture, it has the effect of widening the practical temperature range and significantly lowering the threshold voltage. In these respects, the present invention is applicable to S, which is currently the mainstream of display devices.
It is extremely effective as a basic component of liquid crystal compositions for TN type display.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a liquid crystal display cell prepared in an example of the present invention.

[Explanation of symbols]

1.2. glass substrate 3. transparent electrode 4. Orientation control layer 5. Polarizer 6. sealant

Claims (5)

[Claims] Claim 1: General formula [Formula 1] (In the above formula, R represents a straight chain alkyl group having 1 to 10 carbon atoms, X represents hydrogen or fluorine, and the cyclohexane ring has a trans configuration) A cyclohexylterphenyl derivative characterized by the following: [Claim 2] It is characterized by being represented by the general formula [Formula 2] (in the above formula, R represents a straight-chain alkyl group having 1 to 10 carbon atoms; and the cyclohexane ring is in a trans configuration) Cyclohexylterphenyl derivative according to claim 1. [Claim 3] It is characterized by being represented by the general formula: [Formula 3] (In the above formula, R represents a straight-chain alkyl group having 1 to 10 carbon atoms, and the cyclohexane ring has a trans configuration.) Cyclohexylterphenyl derivative according to claim 1. Claim 4: General formula: [Formula 4] (In the above formula, R represents a straight chain alkyl group having 1 to 10 carbon atoms, X represents hydrogen or fluorine, and the cyclohexane ring has a trans configuration.) A liquid crystal composition comprising at least one type of cyclohexylterphenyl derivative shown below. [Claim 5] General formula [Image Omitted] (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms, X represents hydrogen or fluorine, and the cyclohexane ring has a trans configuration.) A liquid crystal display element characterized by using a liquid crystal composition containing at least one of the cyclohexylterphenyl derivatives shown below.