JPH03218337A - Liquid crystal compound - Google Patents

Abstract

NEW MATERIAL:A liquid crystal compound expressed by the formula (R1 is 8-18C alkyl; R2 is 6-16C alkyl; * is optically active center). EXAMPLE:4-(1,1,1-Trifluoro-2-decyloxycarbonyl)pheny-4-n-decanoyl-oxybe nzoate. USE:A liquid crystal compound useful for display element which utilizes the response to electric field and electrooptical element. Especially the liquid crystal compound exhibits a three stable state phase at a below-zero temperature and can be utilized for display which drives at below-zero temperature and electro- optical element. The liquid crystal compound exhibits a molecular orientation state being clear in contrast of light and darkness and exhibits a clear threshold characteristics and histeresis as well as dynamic driving and high speed response. PREPARATION:A reaction product of 4-benzyloxybenzoic acid chloride and optically active 1,1,1-trifluoro-2-alkanol is subjected to a hydrogenation reaction and then the hydrogenation product made to reacted with 4-n- alkylcarbonyloxyphenylcirboxylic acid to provide the compound expressed by the formula.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a ferroelectric smectic liquid crystal display, and the liquid crystal compound is used in display elements and electric devices that utilize response to an electric field. This invention relates to liquid crystal compounds used in optical elements.

Furthermore, the present invention relates to ferroelectric liquid crystal compounds that exhibit three stable molecular orientation states. The liquid crystal compound is used in display elements and electro-optical elements that utilize response to an electric field. In particular, the liquid crystal compound exhibits a king stable state phase at temperatures below freezing and is used in display elements and electro-optical elements that are driven at temperatures below freezing.

[Prior art]

As electro-optical devices using liquid crystals, electro-optical devices using nematic liquid crystals such as DSM type, TN type, GH type, and STN type have been developed and put into practical use. However, all of the devices using such nematic liquid crystals have the disadvantage that the response speed is extremely slow, ranging from several meters to several tens of milliseconds, which limits their field of application. The response speed of devices using nematic liquid crystals is slow because the torque that moves the molecules is basically based on the anisotropy of the dielectric constant, so the force is not very strong. In this background, it has spontaneous polarization (Ps) and the torque is PsXE (
ferroelectric liquid crystals were developed by Meyer et al. (L
rnalda Physique, vol. 36, 197
5, L-69), and Japanese Patent Laid-Open No. 63-307837 discloses a newer ferroelectric liquid crystal, but there is little disclosure regarding the "three states" described below.

Several high-speed electro-optical devices using ferroelectric liquid crystals have already been proposed.

A typical example is one in which the twisted structure is untwisted by the force of the wall surface, and the orientation of two molecules parallel to the wall surface is changed by the polarity of the applied electric field (for example, Japanese Patent Application Laid-Open No. 107-216-1982).
(see issue).

The above method is based on the premise of the existence of a compound exhibiting two ideal states as shown in the electric field response waveform of FIG. However, in reality, a compound exhibiting the ideal two states has not been discovered, and the electric field response waveforms of the two-state liquid crystals synthesized so far are as shown in Figure 2, and as shown in Figure 1. No response waveform was obtained. If you try to use a response waveform like that shown in Figure 2 in, for example, an optical switching circuit, the transmittance will gradually change as the applied voltage changes from e to The reality is that simply changing the applied voltage between ON and OFF cannot sufficiently accomplish the purpose. Furthermore, in the two-state liquid crystals synthesized so far, it is difficult to create a monodomain state, which is an ideal molecular orientation state, in the S''c phase stage in the absence of an electric field, resulting in disclinations (defects) and twisting. Therefore, it is difficult to realize the ideal two-state orientation in a large area.Furthermore, since the threshold value (voltage at which the brightness changes by a predetermined value) is low, when dynamic driving is performed, The contrast may be reduced and the viewing angle range may be narrowed.In addition, the two-state liquid crystals synthesized so far are
Since it cannot show the hysteresis as shown in the figure and can only show the hysteresis as shown in Fig. 2, there is no memory effect. Therefore, in order for the liquid crystal to maintain a stable response in the SIc phase, it is necessary to continue applying the voltage υ3 in Figure 2, or to continue applying a high frequency. Energy loss is large.

In the end, although there is a desire for a high-speed liquid crystal electro-optical device that effectively utilizes the strong coupling between the applied electric field and molecular orientation obtained in ferroelectric liquid crystals, there are still many problems with conventional ferroelectric liquid crystal electro-optical devices. The reality is that this remains the case.

Therefore, in the present invention, a stable molecular orientation state with a clear contrast between light and dark is realized without an electric field, a clear threshold characteristic and a clear hysteresis as shown in Figure 3 appear, and dynamic movement is easily realized. The object of the present invention is to provide a new liquid crystal compound that can be used in a liquid crystal electro-optical device that utilizes three states and that also enables high-speed response.

〔the purpose〕

The purpose of the present invention is to develop a ferroelectric liquid crystal exhibiting a chiral smectic phase and a novel material having a completely new king state, which is different from the chiral smectic C phase (S"c phase), which is a conventional bistable phase. The object of the present invention is to provide a ferroelectric liquid crystal.

The above-mentioned "having three states" refers to a liquid crystal electro-optical device in which a ferroelectric liquid crystal is sandwiched between a first electrode substrate and a second electrode substrate disposed with a predetermined gap. The structure is such that a voltage for forming an electric field is applied to the first and second electrode substrates, and when the voltage is applied in the form of a triangular wave shown in FIG. 4A, the ferroelectric liquid crystal However, when there is no electric field, the molecular orientation has a first stable state (■ in Figure 4 D), and when an electric field is applied, the molecular orientation is in a second stable state in one electric field direction, which is different from the first stable state. (■ in Figure 4 D), and furthermore, a third stable state of molecular orientation (■ in Figure 4 D) different from the first and second stable states with respect to the other electric field direction. It means to have. Regarding the liquid crystal electro-optical device that utilizes these three stable states, that is, the three states, the present applicant has filed a patent application in 1983-1970.
The application has been filed as No. 212.

-6- On the other hand, "commercially available nematic liquid crystals" and two-state liquid crystals synthesized so far do not have three stable states, as shown in FIGS. 4B and C.

This new king-state ferroelectric liquid crystal exhibits revolutionary effects when used in liquid crystal displays compared to conventional nematic liquid crystals.

In contrast to the conventional type, which required a very complex structure with an active matrix driving method, the three-state ferroelectric liquid crystal requires a simple matrix type display. For this reason, in the case of the conventional type, the production process is complicated, making it difficult to enlarge the screen, and the manufacturing cost is also high, whereas in the case of king-state ferroelectric liquid crystal, the production process is simple, and the screen This is an epoch-making technology that allows for larger sizes and lower manufacturing costs.

An object of the present invention is to provide a novel liquid crystal exhibiting this king-state ferroelectricity.

[Configuration of the present invention]

The present invention provides formula -7, [wherein R1 is an alkyl group having 8 to 18 carbon atoms, preferably a straight-chain alkyl group, particularly preferably a straight-chain alkyl group having 9 or 10 carbon atoms, and R2 is a straight-chain alkyl group having 6 to 18 carbon atoms. -16 alkyl group, preferably a straight chain alkyl group, particularly preferably a straight chain alkyl group having 6 to 8 carbon atoms, and * indicates an optically active center. ] The present invention relates to a liquid crystal compound exhibiting a tristable state at sub-zero temperatures, characterized by being composed of a compound represented by the following.

Although the liquid crystal compound of the present invention can be used alone, it is possible to adjust the properties of the liquid crystal by mixing the compounds of the present invention with each other, with other liquid crystal compounds, or with a compound having a similar structure. It can be put to practical use.

As a result of the analysis of the liquid crystal compound represented by the above general formula of the present invention, it was found that the key to exhibiting the tristable state is as follows.

(i) CF bonded to an asymmetric carbon atom most influences the expression of the tristable state. When CF3 is replaced with CH, almost no tristable state is expressed.

(ii) In the above formula, it is necessary for the expression of the tristable state that the direction of the ester is the same as the direction of -CO- bonded to the asymmetric carbon O atom.

Synthesis examples of the compounds of the present invention include the following.

4-penzyloxybenzoic acid chloride and optically active 1
, 1.1-trifluoro-2-alkanol to obtain 4-benzyloxybenzoic 1,1.1-trifluoro-2-alkyl ester, which was hydrogenated to give 4-hydroxybenzoic acid. A 1,1,1-trifluoro-2-alkyl ester was obtained.

The obtained alkyl ester and 4-n-alkylcarbonyloxyphenylcarboxylic acid are reacted in the presence of dicyclo-9-hexyllupodiimide to obtain the target compound, optically active 4-(1,1.1-trifluorocarbon). 2-alkyloxycarbonyl)phenyl 4-n-alkylcarbonyloxybenzoate is obtained.

〔Example〕

The compounds of the present invention will be explained below with reference to Examples.
It is not limited to this.

Oxybenzoate 1.23 g of 4-penzyloxybenzoic acid chloride was dissolved in 10-methylene chloride, and then optically active 1,1.
1-triphnoreol 2-decanol 0.96 g, dimethylaminopyridine 0.55 g and triethylamine 0
．． A solution prepared by dissolving 48 g of 20 g of chloride in 20 parts of methylene chloride was added little by little under cooling with water.

The reaction mixture was returned to room temperature and allowed to react overnight. The reaction mixture was poured into ice water and extracted with methylene chloride. The methylene chloride phase was washed successively with diluted hydrochloric acid, water, IN aqueous sodium carbonate solution, and water, and then extracted with anhydrous magnesium sulfate. After drying and distilling off the solvent, a crude product was obtained. This was treated with toluene-silica gel force column chromatography and further recrystallized from ethanol to obtain 1.84 g of the desired product.

The compound obtained in 81) of cybenzoate was dissolved in 15 mfi of ethanol, 0.36 g of 10% supported Pd-carbon was added, and a hydrogenation reaction was carried out under a hydrogen atmosphere to obtain 1.43 g of the target compound.

11 3) Synthesis of 4-n-decanoyloxyn 3 g of p-hydroxybenzoic acid and 2.4 g of triethylamine
Dissolve g in dichloromethane.

Add 4.3 g of decanoyl chloride and 0.2 g of dimethylaminopyridine, and stir at room temperature for about 20 hours.

Add dilute hydrochloric acid and separate the organic layer using a separating funnel. The solvent is distilled off, and the residue is washed with n-hexane and dried to obtain about 5 g of the target compound.

0.4 g of 4-n-decanoyloxybenzoic acid obtained in 3)
and 0.4 g of 1,1,1-trifluoro-2-decyl 4-hydroxybenzoate obtained in 2) are dissolved in about 30 mQ of -12-tetrahydrofuran. Dicyclohexyllupodiimide 0.32g and dimethylaminopyridine 0.32g.
01 g and stirred at room temperature for about 20 hours. After distilling off the solvent, the residue is dissolved in dichloromethane and washed with water. After drying the organic layer over anhydrous magnesium sulfate, the solvent was distilled off. The residue was chromatographed on silica gel (
Purification is performed using a developing solvent: hexane/ethyl acetate = 20/1) to obtain 0.15 g of the target compound.

The following phase transition temperature ('C) was obtained by observing the hot stage with a polarized light microscope.

Here, S"(3) is a phase exhibiting a tristable state, and Sx is a higher-order phase that responds to an electric field. The infrared absorption spectrum of this compound is shown in FIG.

, 4.3 g of 4-penzyloxybenzoic acid chloride of 84-penzyloxybenzoate is dissolved in 50-methylene chloride, and then optically active 1,1.1
-}2.9 g of refluoro-2-octanol, 0.6 g of dimethylaminopyridine, and 1.7 g of triethylamine
A solution prepared by dissolving 50% of methylene chloride was added little by little under water cooling.

The reaction mixture was returned to room temperature and allowed to react overnight. The reaction mixture was poured into ice water and extracted with methylene chloride. The methylene chloride phase was washed successively with diluted hydrochloric acid, water, IN sodium carbonate aqueous solution, and water, and then extracted with anhydrous magnesium sulfate. After drying and distilling off the solvent, a crude product was obtained. This was treated with toluene-silica gel force column chromatography and further recrystallized from ethanol to obtain 3.8 g of the desired product.

2) The compound obtained in A 1) of 111-1 fluoro-2-octyl 4-hydroxybenzoate was dissolved in 100 mQ of methanol, 0.4 g of 10% supported Pd-carbon was added, and the hydrogenation reaction was carried out under a hydrogen atmosphere. 2.8 g of the target compound was obtained.

0.43 g of 4-n-decanoyloxybenzoic acid obtained in 3) of Example 1 and 0.43 g of 1,1.1-trifluoro-2-octyl-4-hydroxybenzoate obtained in 2) of this example.
．． 4 g are dissolved in about 30 g of tetrahydrofuran. Add 0.32 g of dicyclohexyllupodiimide and 0.01 g of dimethylaminopyridine, and mix at room temperature for about 2
Stir for 0 hours. After distilling off the solvent, the -15- residue is dissolved in dichloromethane and washed with water.

After drying the organic layer over anhydrous magnesium sulfate, the solvent is distilled off. The residue was purified using silica gel column chromatography (developing solvent: hexane/ethyl acetate = 20/1),
0.20 g of the target compound is obtained.

The following phase transition temperature (°C) was obtained by observing the hot stage with a polarized light microscope.

Here, S (3) is a phase exhibiting a tristable state, and Sx is a higher-order phase that responds to an electric field. The infrared absorption spectrum of this compound is shown in FIG.

1) 3 g of 4-n-unkanoyloxy p-hydroxybenzoic acid and 2.4 g of triethylamine
Dissolve g in 30 mQ of dichloromethane.

Add 4.5 g of 1161 undecanoyl chloride and 0.2 g of dimethylaminopyridine, and stir at room temperature for about 20 hours. Dilute hydrochloric acid is added, and the organic layer is separated using separator flow 1. The solvent is distilled off, and the residue is washed with n-hexane and dried to obtain about 5 g of the target compound.

4-n-undecanoyloxybenzoic acid obtained in step (2) 0.
3 g and 0.3 g of 1,1,1-trifluoro-2-decyl 4-hydroxybenzoate obtained in 2) of Example 1 are dissolved in about 301 g of tetrahydrofuran. Add 0.25 g of dicyclohexyllupodiimide and 0.01 g of dimethylaminopyridine, and stir at room temperature for about 20 hours. After distilling off the solvent, the residue is dissolved in dichloromethane and washed with water.

After drying the organic layer over anhydrous magnesium sulfate, the solvent was distilled off. The residue was purified by silica gel column chromatography (developing solvent: hexane/ethyl acetate = 20/1) to obtain 0.21 g of the target compound.

The following phase transition temperature ('C) was obtained by observing the hot stage with a polarized light microscope.

Here, S'' (3) is a phase exhibiting three stable states.

The infrared absorption spectrum of this compound is shown in FIG.

A liquid crystal cell having a cell thickness of 2.1 μm and having a polyimide alignment film subjected to a clay rubbing treatment on an ITO electrode substrate was filled with the liquid crystal compound obtained in Example 2 in an isotropic phase to prepare a liquid crystal thin film cell.

This liquid crystal cell was placed in a polarizing microscope equipped with a photomultiplier with two polarizing plates perpendicular to each other, with the polarizer making an angle of 22.5° with the long axis direction of the molecules when no voltage was applied. This liquid crystal cell was heated at a temperature gradient of 0.1 to 1.0°C/1 minute.
” It was gradually cooled to the (3) phase.

After further cooling, in the temperature range of -5°C to -13°C, ±30V. FIG. 5 shows the case where a 10 Hz triangular wave voltage (a) was applied. The light transmittance changes into three states (b): a dark state when the applied voltage is in the negative range, an intermediate state when it is in the O volt range, and a bright state when it is in the positive range, and there are three stable alignment states of liquid crystal molecules. It was confirmed. The same effect was observed with the compounds of other examples.

〔effect〕

All of the novel liquid crystals of the present invention exhibit a stable king state, and have a wide range of applications such as display devices and switching devices that utilize this.

[Brief explanation of drawings]

Figure 1 shows the hysteresis of an ideal two-state liquid crystal that has not been obtained in reality, Figure 2 shows the hysteresis of two-state liquid crystals that have actually been synthesized to date, and Figure 3 shows the hysteresis of a three-state liquid crystal according to the present invention. Each indicates the hysteresis of the liquid crystal.
In both Figures 1 to 3, the horizontal axis represents the applied voltage, and the vertical axis represents the transmittance (%).
)19 is shown. In FIG. 4, A shows the optical response characteristics of an applied triangular wave, B shows the optical response characteristics of a commercially available nematic liquid crystal, C shows the two-state liquid crystal synthesized so far, and D shows the three-state liquid crystal. Figure 5 shows the king state switching of the compound of the present invention, in which a shows the triangular wave voltage applied to the liquid crystal electro-optical element, and b shows the change in light transmittance with respect to the triangular wave voltage shown in a. This is what is shown. FIG. 6 is an infrared absorption spectrum of the compound of the present invention of Example 1. FIG. 7 is an infrared absorption spectrum of the compound of the present invention of Example 2. 8th
The figure shows an infrared absorption spectrum of the compound of the present invention of Example 3. -20- Soso J% Adoption! l-Sho July 9, 1990

Claims (1)

[Claims] 1. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 is an alkyl group having 8 to 18 carbon atoms, R_2
is an alkyl group having 6 to 16 carbon atoms, and * indicates an optically active center. ] A liquid crystal compound exhibiting a tristable state characterized by being composed of a compound represented by the following.