JPH0643384B2 - Liquid crystalline compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal compound, and more specifically, to an optically active liquid crystal compound, a chiral liquid crystal composition containing the same, and the liquid crystal composition. The present invention relates to a liquid crystal element.

Background Art As a conventional liquid crystal element, for example, M.Sch
adt) and W. Helfrich, "Applied, Physics, Letters," Vol. 18, No. 4 ("Appl
ied Physics Letters ”, Vol.18, No.4) (1971.2.15),
“Voltage-Dependent Optical Activity of a T.” of P.127-128.
TN listed in wisted Nematic Liquid Crystal ”)
Those using a (twisted nematic) liquid crystal are known. However, this TN liquid crystal, when time-division drive using a matrix electrode structure with high pixel density,
The number of pixels is limited because of the problem of crosstalk. Further, since the electric field response is slow and the viewing angle characteristic is poor, the use as a display is limited.

Furthermore, a display element of a type in which a switching element using a thin film transistor is connected to each pixel and switching is performed for each pixel is known, but a process of forming a thin film transistor on a substrate is extremely complicated, and a large area display element is used. There are problems that are difficult to create.

The use of bistable liquid crystal devices is one of the methods to improve the drawbacks of the conventional liquid crystal devices.
rk) and Lagerwall (JP-A-56-107216, US Pat. No. 4,367,924, etc.). As a liquid crystal having bistability, a chiral smectic C phase (SmC ^* ) or an H phase (Sm) is generally used.
A ferroelectric liquid crystal having H ^* ) is used.

Since this ferroelectric liquid crystal has a spontaneous polarization, it has a very fast response speed, and can express a bistable state with a memory property. Moreover, it has a large viewing angle characteristic and thus has a large capacity and a large capacity. Suitable as a screen display. However, the conventionally known ferroelectric liquid crystal generally has a chiral smectic layer at a relatively high temperature, and has a problem that it is difficult to drive it near room temperature.

OBJECT OF THE INVENTION The present invention has been made in view of the above points. That is, the present invention has a liquid crystal compound having a smectic liquid crystal phase at around room temperature or having an effect of lowering the temperature of a SmC ^* phase and expanding when mixed, a liquid crystal composition containing at least one thereof, and the liquid crystal composition. An object of the present invention is to provide a liquid crystal device using the.

SUMMARY OF THE INVENTION That is, the present invention provides a compound represented by formula (I) (Wherein R is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, n is 1 or 2, and C ^* is an asymmetric carbon atom). .

The present invention also provides a liquid crystal composition containing at least one kind of the above-mentioned optically active liquid crystalline compound as a component, and a liquid crystal element using the liquid crystal composition.

DETAILED DESCRIPTION OF THE INVENTION In the liquid crystal compound of the general formula (I), the type and temperature range of the liquid crystal phase to be developed can be controlled by adjusting the carbon number of R, and the liquid crystal compound has 1 to 18 carbon atoms. It is possible to use those having 4 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and the viscosity and Sm.
It is selected in terms of the temperature range of the C ^* phase.

The liquid crystalline compound represented by the general formula (I) is preferably the one of the application by the present applicant (the title of the invention is “optically active substance and liquid crystal composition containing the same” dated April 30, 1986). It is synthesized from an optically active intermediate such as 4- (2′-methylbutyl) benzenethiol shown in the specification.

For example, the liquid crystal compounds shown below can be obtained from these optically active intermediates by the synthetic route shown below.

(Here, R, n, and ^* have the same meanings as above.) Table 1 shows examples of the liquid crystal compound thus obtained.

In the table, the symbols in the column of phase transition temperature indicate the following phases, respectively.

Cryst .: crystalline phase, SmA: smectic A phase, SmC ^* : chiral smectic C phase, N: nematic phase, Ch .: cholesteric phase, Iso: isotropic phase, Sm3: SmA, smectic phase other than SmC ^* (unidentified) ) The liquid crystal composition of the present invention contains at least one liquid crystal compound represented by the general formula (I) as a blending component. For example, when the liquid crystalline compound represented by the general formula (I) is combined with a ferroelectric liquid crystal represented by the following (1) to (13), SmC ^* can be lowered and the temperature range can be expanded. It will be possible.

In such a case, the liquid crystal compound of the present invention represented by the general formula (I) is added to the obtained liquid crystal composition in an amount of 1 to 99%.
It is preferable to use it in an amount of 9% by weight, particularly 9 to 95% by weight.

(1) 4-octyloxybenzoic acid 4 '-(2-methylbutyloxy) phenyl ester (2) 4-nonyloxybenzoic acid 4 '-(2-methylbutyloxy) phenyl ester (3) 4-decyloxybenzoic acid 4 '-(2-methylbutyloxy) phenyl ester (Four) 4-Undecyloxybenzoic acid 4 '-(2-methylbutyloxy) phenyl ester (Five) 4-dodecyloxybenzoic acid 4 '-(2-methylbutyloxy) phenyl ester (6) 4-decyloxybenzoic acid 4 '-(2-methoxypropyloxy) phenyl ester (7) 4,4'-azoxycinnamic acid-bis (2-
Methyl butyl) ester (8) 4-o- (2-methyl) -butylresorcylidene-4 '
-Octylaniline (MBRA 8) (9) 4- (2'-methylbutyl) phenyl-4'octyloxybiphenyl-4-carboxylate (Ten) 4-hexyloxyphenyl-4- (2 "-methylbutyl) biphenyl-4'-carboxylate (11) 4-octyloxyphenyl-4- (2 "-methylbutyl) biphenyl-4'-carboxylate (12) 4-heptylphenyl-4- (4 "-methylhexyl)
Biphenyl-4'-carboxylate (13) 4- (2 "-methylbutyl) phenyl-4- (4" -methylhexyl) biphenyl-4'-carboxylate Further, by compounding with a smectic liquid crystal which is not chiral itself as shown in the following formulas 1) to 5), a composition usable as a ferroelectric crystal can be obtained.

In this case, the liquid crystal compound of the present invention represented by the general formula (I) is used in an amount of 1 to 99% by weight, particularly 5 to 99% by weight of the obtained liquid crystal composition.
It is preferably used at 95% by weight.

1) (4-nonyloxyphenyl) -4'-octyloxybiphenyl-4-carboxylate 2) 4,4'-decyloxyazoxybenzene 3) 2- (4'-hexyloxyphenyl) -5- (4-hexyloxyphenyl) pyrimidine Four) 2- (4'-octyloxyphenyl) -5-nonylpyrimidine Five) 4'-Pentyloxyphenyl-4-octyloxybenzoate Here, the symbols indicate the following phases, respectively.

Cryst .: crystalline phase, SmA: smectic A phase, SmB: smectic B phase, SmC: smectic C phase, N: nematic phase, Iso .: isotropic phase.

Liquid crystal compound represented by the general formula (I) Effects of the Invention The present invention at relatively low temperatures indicate the SmC ^* phase, and since that indicates the stable SmC ^* phase in a wide temperature range, as a ferroelectric liquid crystal device material It is effective when used. Further, the general formula (I) of the present invention
The liquid crystal composition containing at least one kind of the liquid crystal compound represented by is capable of expanding the temperature range of the SmC ^* phase while lowering the temperature range, and is effective in improving the characteristics.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 4-octyloxythiobenzoic acid -S- represented by the following formula
4 '-(2-Methylbutyl) phenyl was prepared.

4-octyloxybenzoic acid 2.78 g was added to benzene 10
Then, 2.36 g of PCl ₅ was added little by little under stirring at room temperature, and the mixture was heated under reflux for 4 hours. After that, the solvent was distilled off, and 4-
Octyloxybenzoic acid chloride was obtained.

2.0 g of 4- (2'-methylbutyl) benzenethiol
And 0.88 g of pyridine were dissolved in 10 ml of toluene and ice-cooled, and 4-octyloxybenzoic acid chloride dissolved in 10 ml of toluene was added dropwise at 2 ° C. over 11 minutes, followed by stirring at room temperature for 24 hours.

After the reaction was completed, the reaction mixture was poured into cold water, and 6N HCl was added.
The solution was acidified and the precipitated crystals were filtered off. The remaining organic layer was washed successively with water, 2N NaOH solution and water, dried over anhydrous sodium sulfate, and the solvent was distilled off to give 4.0.
g crystals were obtained.

The above crystals were purified by silica gel column chromatography using a mixed liquid of n-hexane / chloroform = 2/1 as a mobile phase, and further recrystallized from ethanol to give 1.
17 g of 4-octyloxythiobenzoic acid S-4'-
(2-Methylbutyl) phenyl was obtained.

IR and NMR data of the product are as follows.

IR (cm _-1 ): 2970, 2925, 2860, 1665, 1605,
1512, 1310, 1270, 1215, 1170,
905.

NMR (ppm): 8.0-6.9 (8H), 4.1-3.9 (2H), 2.6-2.4 (2H), 1.8-0.8 (24H).

Examples 2 and 4 By the same method as in Example 1, liquid crystal compounds of the present invention were obtained. The products are listed in Table 1 above along with their phase transition temperatures.

Example 3 4'-heptylphenylthiocarboxylic acid -S-4- (2'-methylbutyl) phenyl represented by the following formula was prepared.

3.29 g of 4-heptylbiphenylcarboxylic acid was put in 10 ml of benzene, 2.36 g of PCl ₅ was added little by little under stirring at room temperature, and the mixture was heated under reflux for 4 hours. Then, the solvent was distilled off to obtain 4-heptylbiphenylcarboxylic acid chloride.

2.0 g of 4- (2'-methylbutyl) benzenethiol
And 0.88 g of pyridine are dissolved in 10 ml of toluene and the temperature is 0 ° C.
At 10 ml of a toluene solution of the heptylbiphenylcarboxylic acid chloride obtained above was added dropwise over 15 minutes. Then, it stirred at room temperature for 24 hours.

After completion of the reaction, the reaction mixture was poured into ice water and acidified with 6N HCl solution, and the precipitated crystals were filtered. The organic layer,
It was washed with water, 2N NaOH solution and water, dried over anhydrous sodium sulfate, and the solvent was distilled off to obtain 5.0 g of crude crystals.
Further recrystallization from ethanol gave 1.7 g of 4'-heptylbiphenylthiocarboxylic acid-S-4- (2'-methylbutyl) phenyl.

IR and NMR data of the product are as follows.

IR (cm _-1 ): 2960, 2930, 2855, 1670, 1600,
1495, 1465, 1400, 1175, 912, 8
10.

NMR (ppm): 8.1-7.1 (12H), 2.8-2.4 (4H), 1.9-0.8 (22H), Example 5 It is a known ferroelectric liquid crystal compound. 4- (4 "-methylhexyloxy) benzoic acid-4'-octyloxyphenyl ester (A below) and 4-dodecyloxythiobenzoic acid S-4 '-(2 obtained according to Example 2 of the present invention. −
Methyl butyl) phenyl ester (B below) was mixed in equal amounts as follows. The obtained liquid crystal composition showed a SmC ^* phase from 53 ° C. to 16 ° C. during the cooling process.

A: B: Example 6 Liquid Crystal Device Using Liquid Crystal Composition Produced in Example 5 About 1000Å on high precision polished glass of 10 × 20 mm.
ITO film is used as an electrode, and S of about 1000Å
iO ₂ was deposited by the ion beam method. The liquid crystal composition produced in Example 5 was dropped on a glass substrate processed in the same manner, and the above glass substrates were stacked facing each other. 60 ° C
While holding the substrate in place, the parallel movement was performed under a polarizing microscope while keeping the distance between the upper and lower substrates, and parallel movements were obtained. As a result, horizontally aligned monodomains were obtained. The liquid crystal layer thickness at that time was 1.4 μm, and after sealing the periphery to form a cell, at 35 ° C., ± 20 V, 1 m
Switching was performed by applying a pulse of sec.

Claims (3)

[Claims] 1. The following general formula (I): (Wherein R is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, n is 1 or 2, and C ^* is an asymmetric carbon atom). 2. The following general formula (I) (Here, R is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, n is 1 or 2, and C ^* is an asymmetric carbon atom.) At least one liquid crystal compound represented by the formula A liquid crystal composition comprising: 3. The following general formula (I) (Here, R is an alkyl group or an alkoxy group having 1 to 18 carbon atoms, n is 1 or 2, and C ^* is an asymmetric carbon atom.) At least one liquid crystal compound represented by the formula A liquid crystal device comprising a liquid crystal composition containing as.