JPH0532675A - Liquid crystal compound - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a completely new type of liquid crystal compound containing boron as a heterocyclic constituent element. [Structure] General formula (1) (In the formula, R ₁ is an alkyl group having 4 to 16 carbon atoms, R ₂ is an alkyl group having 4 to 14 carbon atoms, X is F, Br, Cl, C
Any atom or group of H ₃ and H, Rf is CF ₃ , CH
₂ F, CHF ₂ , or C ₂ F ₅ group, * represents an optically active center. ) A liquid crystal compound represented by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a ferroelectric chiral smectic liquid crystal compound, which relates to a liquid crystal compound used in a display device or an electro-optical device utilizing a response to an electric field. Is. Furthermore, the present invention relates to a ferroelectric liquid crystal compound that exhibits three stable molecular alignment states. The liquid crystal compound is used for a display element or an electro-optical element that utilizes the response to an electric field.

[0002]

2. Description of the Related Art As an electro-optical device using liquid crystal, a DS
Electro-optical devices using nematic liquid crystals such as M type, TN type, GH type and STN type have been developed and put into practical use.
However, all of those using such a nematic liquid crystal have a drawback that the response speed is extremely slow, from several meters to several tens of msec, and therefore their application fields are limited. The reason why the response speed of the device using the nematic liquid crystal is slow is that the torque for moving the molecule is basically based on the anisotropy of the dielectric constant, and the force is not so strong. Against this background, it has a spontaneous polarization (Ps) and the torque is based on Ps × E (E is an applied electric field). Therefore, the force is strong and a high-speed response of several μsec to several tens μsec is possible. A ferroelectric liquid crystal was developed by Meyer et al.
e Journal de Physique, 36
Vol., 1975, L-69). Further, recently, a new liquid crystal compound exhibiting an optical tristable state was discovered by the present inventors, and the inventors of the present invention have disclosed JP-A-63-307837.
Japanese Unexamined Patent Publication No. 1-216390, Japanese Unexamined Patent Publication No. 1-131667, Japanese Unexamined Patent Publication No. 1-316339, Japanese Unexamined Patent Publication No. 2-131450, Japanese Unexamined Patent Publication No. 2-28128, Japanese Unexamined Patent Publication No. 2-160748 and Ichihashi.
No. In terms of application, some high speed electro-optical devices using ferroelectric liquid crystal have already been proposed. As a typical example, the twisted structure is solved by the force of the wall surface, and the orientation of two molecules parallel to the wall surface is changed according to the polarity of the applied electric field (for example, JP-A-56-56).
107216). The above is premised on the presence of a compound that exhibits two ideal states as shown in the electric field response waveform of FIG. However, in reality, a compound exhibiting the above-mentioned ideal two states has not been found, and the electric field response waveform of the two-state liquid crystal synthesized so far is as shown in FIG. 2, and the response waveform as shown in FIG. Has not been obtained. For example, when it is attempted to utilize a response waveform as shown in FIG. 2 in an optical switching circuit, the applied voltage becomes −
Since the transmittance gradually changes from the (negative) side to the + (positive) side, the reality is that simply changing the applied voltage of ON and OFF cannot achieve the purpose. Furthermore, the two-state liquid crystals that have been synthesized so far have difficulty in producing an ideal molecular orientation state, that is, a monodomain state, in the S * c phase stage in the absence of an electric field, causing disclination (defects) and twisting. Distortion of the molecular orientation is called. Therefore, in the large area, the ideal 2
It is difficult to realize the state orientation. Further, since the threshold value (the voltage at which the brightness changes by a predetermined value) is low, the contrast is lowered or the viewing angle range is narrowed when dynamic driving is performed. Further, the two-state liquid crystal synthesized so far cannot exhibit the hysteresis as shown in FIG. 1 and exhibits only the hysteresis as shown in FIG. 2, so that it has no memory effect. Therefore, S * c which is stable in liquid crystal
In order to maintain the response in the phase, it is necessary to keep applying the voltage of υ ₃ in FIG. 2 or keep applying the high frequency, and the energy loss is large in any case. After all, although a high-speed liquid crystal electro-optical device that effectively utilizes the strong coupling between the applied electric field and the molecular orientation obtained in the ferroelectric liquid crystal is desired, many problems still remain in the conventional ferroelectric liquid crystal electro-optical device. It is the actual situation that is left. Therefore, the present invention not only provides a novel liquid crystal compound having two states, but also realizes three stable molecular alignment states with clear bright and dark contrasts in the absence of an electric field, with clear threshold characteristics and as shown in FIG. It is an object of the present invention to provide a novel liquid crystal compound that can be used in a liquid crystal electro-optical device that utilizes three states, in which a clear hysteresis appears, dynamic driving is easily realized, and high-speed response is possible. .

[0003]

[Object] An object of the present invention is to provide a liquid crystal compound exhibiting a novel bistable state. Another object of the present invention is to provide a ferroelectric liquid crystal exhibiting a chiral smectic phase and a chiral smectic C phase (S *) which is a conventional bistable state phase.
This is to provide a novel ferroelectric liquid crystal having completely new three states different from the (c-phase). The above-mentioned “having three states” means a liquid crystal electro-optical device in which a ferroelectric liquid crystal is sandwiched between a first electrode substrate and a second electrode substrate which is arranged with a predetermined gap. A voltage for forming an electric field is applied to the first and second electrode substrates, and when a voltage is applied as the triangular wave shown in FIG. 4A, the ferroelectric liquid crystal is not present as shown in FIG. 4D. The molecular orientation has a first stable state (in FIG. 4D) when an electric field is applied, and
When an electric field is applied, the molecular orientation has a second stable state (in FIG. 4D) different from the first stable state in one electric field direction, and further, the first and second stable states in the other electric field direction. It is meant to have a third molecular orientation stable state (of FIG. 4D) different from the state. In addition, these three stable states,
That is, regarding the liquid crystal electro-optical device utilizing the three states, the present applicant has applied for a patent application as Japanese Patent Application No. 63-70212 and is disclosed as Japanese Patent Application Laid-Open No. 2-153322.
On the other hand, the “commercial nematic liquid crystal” and the two-state liquid crystal synthesized so far do not have three stable states as seen in FIGS. 4B and 4C. This new three-state ferroelectric liquid crystal exhibits a epoch-making effect when it is used as a liquid crystal display compared with the conventional nematic liquid crystal. In the conventional type, the drive system had to have a very complicated structure called the active matrix system in order to obtain high image quality, whereas the tri-state ferroelectric liquid crystal only requires a simple matrix type display. For this reason, in the case of the conventional type, the production process is complicated, it is difficult to increase the size of the screen, and the manufacturing cost is high, whereas in the case of the three-state ferroelectric liquid crystal, the production process is simple and It is an epoch-making thing that the size can be increased and the manufacturing cost can be reduced. 1 of the present invention
One purpose is to provide a novel liquid crystal exhibiting this tri-state ferroelectricity.

[0004]

[Structure] The present invention has the general formula (1)

[Chemical 3] (In the formula, R ₁ is an alkyl group having 4 to 16 carbon atoms, R ₂ is an alkyl group having 4 to 14 carbon atoms, X is F, Br, Cl, C
Any atom or group of H ₃ and H, Rf is CF ₃ , CH
₂ F, CHF ₂ , or C ₂ F ₅ group, * represents an optically active center. ) Relates to a liquid crystal compound. Examples of the synthesis of the compound of the present invention are as follows. Four
-Benzyloxybenzoyl chloride and optically active 1,
1,1-trifluoro-2-alkanol is reacted to give 4-benzyloxybenzoic acid 1,1,1-trifluoro-2-alkyl ester, which is hydrolyzed to give 4-hydroxybenzoic acid 1 , 1,1-trifluoro-2-alkyl ester was obtained. The obtained alkyl ester and 2- (4-carboxyphenyl) -5-
An alkyl-1,3,2-dioxaborinane is subjected to a condensation reaction in the presence of dicyclohexylcarbodiimide to give an objective compound, optically active 4- (1,1,1-trifluoro-2-alkyloxycarbonyl) phenyl 4-.
(5-Alkyl-1,3,2-dioxaborinane) benzoate is obtained.

[0005]

EXAMPLES The following examples illustrate the compounds of the present invention, but are not limited thereto. Example 1 2- {4 '-[4- (1,1,1-trifluoro-2-
Synthesis of octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-undecyl-1,3,2-dioxaborinane

[Chemical 4] 1) 1,1,1-trifluoro-2-octyl 4-
Synthesis of benzyloxybenzoate

[Chemical 5] 1.23 g of 4-benzyloxybenzoic acid chloride was dissolved in 10 ml of methylene chloride, and then the optically active 1,2
A solution prepared by dissolving 0.96 g of 1,1-trifluoro-2-octanol, 0.55 g of dimethylaminopyridine and 0.48 g of triethylamine in 20 ml of methylene chloride was added little by little under ice cooling. Allow the reaction mixture to come to room temperature,
After reacting overnight, the reaction solution is poured into ice water and extracted with dichloromethane. The dichloromethane layer is washed successively with diluted hydrochloric acid, water, 1N aqueous sodium carbonate solution and water, dried over anhydrous magnesium sulfate and the solvent is distilled off. , A crude product was obtained.
This was treated with a toluene-silica gel column chromatograph and recrystallized with ethanol to obtain 1.84 of the desired product.
g was obtained. 2) Synthesis of 4-hydroxybenzoic acid 1,1,1-trifluoro-2-octyl ester

[Chemical 6] The compound obtained in 1) above is dissolved in 15 ml of ethanol, 0.36 g of 10% supported Pd-carbon is added, and hydrogenolysis reaction is carried out in a hydrogen atmosphere to obtain 1.43 g of the target compound.
Got 3) Synthesis of 2- (4-carboxyphenyl) -5-undecyl-1,3,2-dioxysavolinane

[Chemical 7] The target compound is synthesized by, for example, Japanese Patent Application Laid-Open No. 1-180887, but briefly, it is 2-undecyl-1,3.
-Propanediol 1.14 g and paracarboxyboronic acid 0.83 g were refluxed with 50 ml of toluene for 1-2.
An azeotropic dehydration reaction was carried out for a time to obtain the desired product. 4) Synthesis of 2- (4'-carboxyfell) -5-undecyl-1,3,2-dioxaborinane chloride

[Chemical 8] 1.23 g of the compound obtained in 3) above was added to thionyl chloride 1
Dissolve in 5 ml, reflux and stir for 4 hours to react,
Excess thionyl chloride was distilled off under reduced pressure to obtain the target compound 1.
08 g was obtained. 5) Synthesis of 2- {4 '-[4- (1,1,1-trifluoro-2-octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-undecyl-1,3,2-dioxaborinane 4) 2- (4'-carboxyphenyl) -5 obtained in
Undecyl-1,3,2-dioxaborinane chloride (1.00 g) was dissolved in dichloromethane (20 ml), and then 4-hydroxybenzoic acid 1,1,1-trifluoro-2-octyl ester (0.81 g) obtained in 2) was dissolved. Dimethylaminopyridine 0.10 g and triethylamine 0.3
A solution of 0 g and 15 ml of dichloromethane was added little by little under ice cooling. The reaction mixture is returned to room temperature, reacted overnight, poured into ice water, extracted with dichloromethane, and the dichloromethane layer is washed successively with diluted hydrochloric acid, water, 1N aqueous sodium carbonate solution and water, and dried over anhydrous magnesium sulfate. Then, the solvent was distilled off to obtain a crude product. This was treated with a silica gel column chromatograph using a mixed solvent of hexane-ethyl acetate 10: 1 as a developing solvent, and recrystallized with ethanol to obtain 1.61 g of the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarizing microscope.

[Table 1] Here, S * (3) is a phase showing a tristable state. The infrared absorption spectrum of this compound is shown in FIG.

Example 2 2- {4 '-[3-Fluoro-4- (1,1,1-trifluoro-2-octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-dodecyl-1,3
Synthesis of 2-dioxaborinane

[Chemical 9] 2-Fluoro-4-benzyloxybenzoic acid chloride was used in place of 4-benzyloxybenzoic acid chloride of 1) of Example 1, and 2-undecyl-1,3-propanediol of 3) of Example 1 was used. 2-dodecyl-
Synthesis was performed using 1,3-propanediol to obtain the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarizing microscope.

[Table 2] Here, S * (3) is a phase showing a tristable state.

Example 3 2- {4 '-[4- (1,1,1-trifluoro-2-
Synthesis of octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-dodecyl-1,3,2-dioxaborinane

[Chemical 10] Synthesis was carried out by using 2-dodecyl-1,3-propanediol instead of 2-undecyl-1,3-propanediol in 3) of Example 1 to obtain the target product. The following phase transition temperature (° C) was obtained by observing the hot stage with a polarizing microscope.

[Table 3] Here, S * (3) is a phase showing a tristable state. The infrared absorption spectrum of this compound is shown in FIG. 7.

Example 4 2- {4 '-[4- (1,1,1-trifluoro-2-
Synthesis of octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-decyl-1,3,2-dioxaborinane

[Chemical 11] Synthesis was carried out by using 2-decyl-1,3-propanediol instead of 2-undecyl-1,3-propanediol in 3) of Example 1 to obtain the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarizing microscope.

[Table 4] Here, S * (3) is a phase showing a tristable state. The infrared absorption spectrum of this compound is shown in FIG.

Example 5 2- {4 '-[3-fluoro-4- (1,1,1-trifluoro-2-octyloxycarbonyl) phenyloxycarbonyl] phenyl} -5-undecyl-1,
Synthesis of 3,2-dioxaborinane

[Chemical 12] Synthesis was carried out by using 2-fluoro-4-benzyloxybenzoic acid chloride instead of 4-benzyloxybenzoic acid chloride of 1) of Example 1 to obtain the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarizing microscope.

[Table 5] Here, S * (3) is a phase showing a tristable state. The infrared absorption spectrum of this compound is shown in FIG.

Example 6 A liquid crystal cell having a cell thickness of 2.1 μm and having a rubbing-treated polyimide alignment film on an ITO electrode was filled with the liquid crystal compound obtained in 1) of Example 1 in an Isotropic phase to form a liquid crystal thin film cell. It was created. This liquid crystal cell has a polarizing microscope with a photomultiplier in which two polarizing plates are perpendicularly arranged.
It was placed at 5 °. This liquid crystal cell
The mixture was gradually cooled to the S * (3) phase with a temperature gradient of 1.0 ° C / 1 minute. Further cooling is performed, and a case where a triangular wave voltage (a) of ± 30 V and 10 Hz is applied in the temperature range of 28 ° C. to 48 ° C. is shown in FIG. There are three stable alignment states of liquid crystal molecules when the applied voltage changes to a dark state in the negative range, an intermediate state in the O-volt range, a bright state in the positive range and the light transmittance changes to three states (b). It was confirmed. The same effect was observed with the compounds of the other Examples.

[0011]

[Effect] The novel liquid crystal of the present invention exhibits stable three states, and has a wide range of uses such as a display device and a switching device.

[Brief description of drawings]

FIG. 1 shows the hysteresis of an ideal two-state liquid crystal that has not been obtained in reality.

FIG. 2 shows the hysteresis of the actually synthesized two-state liquid crystal.

FIG. 3 is a graph showing hysteresis of a three-state liquid crystal according to the present invention. In each of the above figures, the horizontal axis represents applied voltage,
The vertical axis represents the transmittance (%).

FIG. 4 shows the optical response of a triangular wave to which A is applied, B of a commercially available nematic liquid crystal, C of an ideal two-state liquid crystal, and D of a three-state liquid crystal.

FIG. 5 shows three-state switching of the compound of Example 1 of the present invention, in which a is a triangular wave voltage applied to the liquid crystal electro-optical element, and b is a light transmission with respect to the triangular wave voltage of a in the figure. This shows the change in the rate.

FIG. 6 is an infrared absorption spectrum of the compound of Example 1 of the present invention.

FIG. 7 is an infrared absorption spectrum of the compound of Example 3 of the present invention.

FIG. 8 is an infrared absorption spectrum of the compound of Example 4 of the present invention.

FIG. 9 is an infrared absorption spectrum of the compound of Example 5 of the present invention.

Continued front page    (72) Inventor Noriko Yamakawa             3-25 Kasumigaseki, Chiyoda-ku, Tokyo Akira             Within Waxiel Oil Co., Ltd.

Claims (2)

[Claims] 1. A compound represented by the general formula (1): (In the formula, R ₁ is an alkyl group having 4 to 16 carbon atoms, R ₂ is an alkyl group having 4 to 14 carbon atoms, X is F, Br, Cl, C
Any atom or group of H ₃ and H, Rf is CF ₃ , CH
₂ F, CHF ₂ , or C ₂ F ₅ group, * represents an optically active center. ) A liquid crystal compound represented by. 2. A general formula (2): (In the formula, R ₁ is an alkyl group having 4 to 16 carbon atoms, R ₂ is an alkyl group having 4 to 14 carbon atoms, X is F, Br, Cl, C
An atom or group of either H ₃ or H, * indicates an optically active center. ) A liquid crystal compound represented by.