JPH0768175B2 - Liquid crystal material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferroelectric liquid crystal compound useful as a display device having excellent image display responsiveness, and a chiral smectic liquid crystal composition containing the same.

At present, a display element made of a liquid crystal material is a light-receiving type display system, and has features such as low power consumption and the ability to create a thin display device, and is widely put to practical use. On the other hand, EL (electroluminescence) and plasma displays, which are light-emitting display systems and feature high-speed response, are also being actively developed.

[Conventional technology]

Most of the liquid crystals that have been used for display devices so far are nematic liquid crystals, and the mainstream is TN [Twisted Nematic (Tw
isted Nematic)] type. Although this TN type display system has advantages such as small size and low power consumption, it also has a drawback that the response speed of image display is slow. Various attempts have been made to improve this point, but Molecular Crystals and Liquid Crystals (Molecular Crys
tals and Liquid Crystals) Vol. 94, pp. 155-165, only the result of demonstrating the theoretical limit value seems to be the limit to the development of materials for TN type display.

Therefore, in order to overcome the above drawbacks, in recent years, interest has been shifted to the development of chiral liquid crystals in place of nematic liquid crystals, and in particular, considerable progress has been made in ferroelectric liquid crystals.

The first developed ferroelectric liquid crystal was A compound represented by (wherein * represents an asymmetric carbon atom) (hereinafter abbreviated as DOBAMBC), and its liquid crystal phase sequence and phase transition temperature (° C) are as follows.

(Where C is a crystalline phase, S _A is a smectic A phase, S _C ^* is a chiral smectic C phase, S _H ^* is a chiral smectic H phase,
I is an isotropic liquid respectively).

Ferroelectricity is expressed in the chiral smectic C phase (hereinafter abbreviated as S _C ^* ) or the chiral smectic H phase (hereinafter abbreviated as S _H ^* ), which are classified and named according to the molecular arrangement. [A] τ = η / P _s · E [A] (where τ is the response time, η is the viscosity of the liquid crystal material, P _s is the spontaneous polarization, and E is the electric field).
There is a possibility of obtaining a display element that can respond up to
Journal of Physics Fra by RBMeyer
nce) 36, 69 (1975).

[Problems to be solved by the invention]

Compounds shown in Table 1 are typical ferroelectric liquid crystals. However, these compounds are not preferable as a display element material because they undergo isomerization due to light within a short period of time, are unstable to water, and do not exhibit liquid crystallinity due to a hydrolysis reaction.

Recently, ferroelectric liquid crystal compounds shown in Table 2 have been disclosed.

Although these compounds solve the above problems and the spontaneous polarization (P _s ) value is relatively large, the temperature range of the chiral smectic phase exhibiting ferroelectricity is narrow and not practical.

[Means for Solving Problems] As a result of earnest research from the above viewpoints, the present inventors have found that the stability is excellent and the temperature range belonging to the S _C ^* phase or the S _H ^* phase is wide.
The inventors have found a ferroelectric liquid crystal compound having a large P _s value and a liquid crystal composition containing the same, and arrived at the present invention.

That is, the present invention has the general formula [I] (Wherein R represents an alkyl group having 5 to 15 carbon atoms and * represents an asymmetric carbon atom), and a liquid crystal compound having a 1,2-dialenenylethane skeleton.

The present invention also provides a liquid crystal composition containing at least one compound represented by the above general formula [I].

In the general formula [I], the dialleneethane skeleton is named as follows.

Therefore, the compound represented by the above general formula [I] is
It can be named as-[4 '-{p- (R or S) -2-octyloxyphenyl} oxycarbonylphenyl] -2- (4 "-alkoxyphenyl) ethane.

The method for producing the compound represented by the general formula [I] will be described in detail below, but a phenol compound having an optically active group is used as one of the starting materials.

This phenolic compound Can be synthesized by the method described in JP-A-61-22051, and can be obtained from Teikoku Chemical Industry Co., Ltd.

The outline of the method for producing the compound of the present invention is represented by the following formula.

(In the above formula, R represents an alkyl group having 5 to 15 carbon atoms, * represents an asymmetric carbon atom, TEA represents triethyleneamine, and THF represents tetrahydrofuran.) [Function] The compound of the present invention has the following functions. And features.

First, it has no azomethine group (-N = CH-) that can be easily decomposed in an atmosphere containing water,
A group that is isomerized by light Since it does not have, it is very stable against moisture and light.
Next, the compound of the present invention has a wide temperature range in which it exhibits ferroelectricity, and the compounds of the present invention may be used together, or the compound of the present invention and an existing ferroelectric liquid crystal compound such as an ester type, a biphenyl type, a pyrimidine type, etc. It is possible to lower the lower limit of the temperature range showing ferroelectricity to room temperature or lower by mixing with.

Since P _s (spontaneous polarization) values of the compounds of the present invention is as large as 30 nC / cm ² or more, when used as a blend material of mixed system, with reaching the desired melting point lowering, a P _s value of the mixing system It is possible to improve.

〔Example〕

Hereinafter, the present invention will be described with reference to examples, but% in the examples means% by weight.

Production Example 1 Synthesis of 4-alkoxyphenylacetylene [B] In a 500 c.c. three-necked flask equipped with a stirrer, thermometer and reflux condenser, 4-alkoxybromobenzene 0.234 mol, 3-methyl-in a nitrogen stream. 1-butyn-3-ol 29.5
7g (0.352mol), triphenylphosphine 1.00g, dichlorobis (triphenylphosphine) palladium catalyst 0.52
Then, g (0.73 mmol) and triethylamine (200 ml) were charged, dissolved with stirring and 160 mg of copper iodide was added. After stirring at room temperature for 3 hours, the mixture was gradually heated, and the internal temperature was brought to 90 ° C in 30 minutes. The reaction was carried out at this temperature for 20 hours. After the reaction, the temperature was returned to room temperature, triethylamine was distilled off under reduced pressure, 300 ml of ether was added to the residue, washed with water, and dried over anhydrous sodium sulfate. After the
The ether was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 400 g, developing solvent:
Benzene) to obtain the compound of the following formula as an intermediate compound.

A 300 c.c. three-necked flask equipped with a stirrer, a thermometer and a distillation apparatus was charged with 58.4 mmol of the above intermediate compound, 120 ml of anhydrous toluene and 310 mg of sodium hydride (60% Nudur dispersant) in a nitrogen stream, and the mixture was stirred at room temperature for 30 minutes. Stir for minutes. It was heated gradually and the internal temperature was brought to 70 ℃ for 30 minutes. Acetone (By-product reflux starts and distilling out with toluene begins, but the reaction is continued by further heating until the distilling temperature reaches the boiling point of toluene. During this time, 2 hours are required, and the distilled solvent is 60 ml. After completion of the reaction, the temperature was returned to room temperature, 100 ml of benzene was added, washed with water, and dried with anhydrous sodium sulfate.
After that, the organic solvent was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 150 g, developing solvent: hexane) to obtain 4-alkoxyphenylacetylene shown in Table 3 in a yield of 85 to 95%. . Its structure was confirmed by IR and NMR spectra.

The results are shown in Table 3.

Production Example 2 p- (2-octyloxy) phenyl-4-
Production of Bromobenzoate [C] p-[(S) -2-octyloxy] phenol (manufactured by Teikoku Chemical Industry Co., Ltd.) 3.00 in a 100 c.c. three-necked flask equipped with a stirrer, a thermometer and a reflux condenser. g (13.5 mol) and 20 ml of anhydrous pyridine were charged and dissolved with stirring. To this pyridine solution, 3.26 g of 4-bromobenzoyl chloride (14.9 mmo
20 ml of a tetrahydrofuran solution containing 1) was added under ice cooling. After returning the reaction temperature to room temperature, the temperature was brought to the reflux temperature, and the mixture was stirred for 8 hours. After completion of the reaction, ether was added, and the mixture was washed with water, washed with 10% caustic soda with alkaline water, and then washed with water, and then dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (200 mesh silica gel 100 g, developing solvent: gradient of hexane to benzene) to give p- (2- Octyloxy) phenyl-4-bromobenzoate [C] was obtained with a yield of 98%.

The spectral data of this compound was as follows.

Production Example 3 Production of 4- (p-2-octyloxyphenyl) oxycarbonyl-4′-alkoxytran [D] In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, Production Example 2 in a nitrogen stream. 5 mmol of p- (2-octyloxy) phenyl-4-bromobenzoate obtained in
4-alkoxyphenylacetylene obtained in Production Example 1
5.5m mol, triphenylphosphine 100m mol, dichlorobis (triphenylphosphine) palladium catalyst 60mg and triethylamine 60ml were charged and dissolved with stirring, and copper iodide was added.
6 mg was added. After stirring at room temperature for 2 hours, the mixture was gradually heated and the internal temperature was brought to 70 ° C over 30 minutes. The reaction was carried out at this temperature for 8 hours. After the reaction, the temperature was returned to room temperature, triethylamine was distilled off under reduced pressure, 100 ml of ether was added to the residue, washed with water, and dried over anhydrous sodium sulfate. After that, ether was distilled off, and the residue was subjected to silica gel column chromatography (200 mesh silica gel 100 g, developing solvent benzene: hexane =
1: 1) to isolate and purify. Recrystallization from hexane gave 4- (p-2-octyloxyphenyl) oxycarbonyl-4'-alkoxytran [D] in 81-94% yield. The structure of each compound was confirmed by IR and NMR spectral data.

Example. [No. 5] Yield 88% The results are shown in Table 4 together with the phase transition temperatures of the obtained compounds.

Example 1 Preparation of 1- [4 ′-(p-2-octyloxyphenyl) oxycarbonylphenyl] -2- (4 ″ -alkoxyphenyl) ethane [I] (n = 0) Stirrer, thermometer, reflux The 4- (p-) obtained in Preparation Example 3 was placed in a flask equipped with a condenser and a rubber fan for storing hydrogen gas.
2-octyloxyphenyl) oxycarbonyl-4 ′
-Alkoxytran 4.4mmol, 5% palladium-carbon catalyst
500 mg and 10 ml of ethyl acetate were charged. After replacing with hydrogen gas, the reaction was carried out at room temperature. The degree of progress of the reaction was examined by a thin layer chromatography chip. The reaction was almost complete in about 6 hours,
Stirring was continued for another 14 hours in a hydrogen atmosphere. After the reaction, the glass filter catalyst covered with Dicalite was removed, and ethyl acetate was distilled off under reduced pressure. The reaction crude product was purified by silica gel column chromatography (200 mesh silica gel 50 g, developing solvent: benzene / hexane: 1/1). The yield was 84-93%. The structure of each compound is I
It was confirmed by R and NMR spectra.

Example. [Compound No. 5] Yield 84% The results are shown in Table 5 together with the phase transition temperatures of the obtained compounds.

Example 2 The liquid crystal compositions of the following Table 6 were prepared using the liquid crystalline compounds of the present invention of compounds No. 3, No. 4 and No. 5 of Table 5, and the phase transition temperatures thereof were measured. The results are shown in Table 6.

When this liquid crystal composition was applied to a cell having a transparent electrode in which a polyimide film was applied, the surface was roughened to perform parallel alignment treatment, and the cell thickness was controlled to 2 μm, cells with uniform alignment by S _C ^* were obtained. Was obtained. When a square wave voltage of ± 10 V is applied at a temperature of 70 ° C, the response time is 0.39 ms and the contrast is 1
0 display elements were obtained.

Example 3 80% of the liquid crystal composition of Example 2 and the following structural formula A liquid crystal composition comprising 20% of the compound represented by and the phase transition temperature thereof was measured.

When this liquid crystal composition was injected into the same cell as the cell used in Example 2, a cell with uniform alignment of S _C ^* could be obtained. Response time of this cell at 30 ℃ 1.1ms, contrast
It was 13. It was possible to lower the melting point and expand the S _C ^* temperature range by mixing with ester-based materials as well as biphenyl-based and pyrimidine-based liquid crystal compounds.

[Effects of the Invention] As shown in Example 1 above, the compound of the present invention is S _C ^*
It is a compound exhibiting a phase and having ferroelectricity, and it is clear from the results of Examples 2 and 3 that it is an effective component in obtaining a chiral smectic liquid crystal composition in a wide temperature range including room temperature. is there. Such an effect is first achieved by the present invention.

Claims (2)

[Claims] 1. A general formula [I] A liquid crystal compound having a 1,2-diarenylethane skeleton represented by the formula (wherein R represents an alkyl group having 5 to 15 carbon atoms and * represents an asymmetric carbon atom). 2. A general formula [I] (Wherein R represents an alkyl group having 5 to 15 carbon atoms and * represents an asymmetric carbon atom), and at least one liquid crystal compound having a 1,2-dialenenylethane skeleton is contained. A characteristic liquid crystal composition.