JPH05132449A - Liquid crystal compound - Google Patents

Abstract

PURPOSE:To provide a novel optically active anti-ferroelectric liquid crystal compound giving in the absence of electric field stable molecular orientation state with sharp contrast, having evident hysteresis, also capable of quick response, and giving a three-stable state. CONSTITUTION:The objective compound of formula I [R1 and R2 are each 4-18C alkyl; R3 is (halo)alkyl; X is O, CO, etc.; Y is COO, CH2O, etc.; Z is COO, O, etc.; (A) is of formula II, III (t denotes halogen substitution), etc.; (B) is of formula IV, single bond, etc.], e.g. 4-(1,1,1-trifluoro-2-octyloxycarbonyl) phenyl-4''-n-decyloxyterphenyl-4-carboxylate. This compound can be obtained by, e.g. hydrogenolysis of a reaction product from a 4-benzyloxy halide and 1,1,1-trifluoro-2-alkanol to produce 1,1,1-trifluoro-2-alkyl-4-hydroxybenzoate, which is, in turn, is made to react with a 4''-alkyloxyterphenyl-4-carboxylic acid chloride.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel liquid crystal compound containing a terphenyl group. Many of the optically active liquid crystal compounds of the present invention exhibit a bistable state of ferroelectricity and a completely new optical tristable state. Further, 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, 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 + 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 the imprinted electric field), so the force is strong and a high-speed response of several μsec to several tens of μsec is possible. New ferroelectric liquid crystal was developed by Meyer et al. (Le
Journal de Physique, Vol. 36, 1
975, L-69), and JP-A-63-30783.
No. 7, a newer ferroelectric liquid crystal is disclosed. Regarding the "three states" described later, Japanese Patent Application Laid-Open No. 1-3 of the present applicant discloses.
16367, JP-A-1-316372, JP-A-1-31
6339, JP-A-2-28128, JP-A2-1314
50, JP-A-2-160748 and Ichihashi, etc.
No. 213390.

Some high-speed electro-optical devices using ferroelectric liquid crystals have already been proposed. As a typical example, the twisted structure is unraveled by the force of the wall surface, and two molecular orientations parallel to the wall surface are changed by the polarity of the applied electric field (see, for example, JP-A-56-107216). The above is premised on the existence of a compound exhibiting ideal two 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 up to now becomes as shown in FIG. 2, and the response waveform as shown in FIG. Can't get When a device having a response waveform as shown in FIG. 2 is used in, for example, a light switching circuit, the transmittance gradually changes as the printing voltage changes from the (−) to the (+) side. The reality is that simply changing the applied voltage between ON and OFF cannot fulfill the purpose. Furthermore, it is difficult for the two-state liquid crystals that have been synthesized so far to create a mono-domain state that is the ideal molecular orientation state in the S * c phase stage when there is no electric field, resulting in disclination (defects) or twisting. The disordered molecular orientation is generated. Therefore, it is difficult to realize the ideal two-state orientation in a large area. Furthermore, since the threshold value (voltage at which the luminance 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 show the hysteresis as shown in FIG. 1 and only the hysteresis as shown in FIG. Therefore, in order to maintain the stable response in the S * c phase in the liquid crystal, it is necessary to keep applying the voltage of υ ₃ in FIG. 2 or keep applying the high frequency. Is big. 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.

[0004]

[Purpose] Therefore, in the present invention, a stable molecular orientation state in which a bright and dark contrast is clear in an electric field is realized, a clear threshold characteristic and a clear hysteresis as shown in FIG. 3 appear, and dynamic driving is easily performed. 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 that enables high-speed response and that is used as one component of a liquid crystal composition. It is what An object of the present invention is to provide a liquid crystal compound containing a terphenyl group in a molecular skeleton structure and exhibiting a new bistable state. Another object of the present invention is to obtain chiral smectic C phase (S * c) which is a conventional bistable state phase among ferroelectric liquid crystals.
Phase) is to provide a novel antiferroelectric liquid crystal having three completely new states.

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 the voltage is applied as a triangular wave shown in FIG. A second stable state in which the molecular orientation has a first stable state ((2) in FIG. 4D) when there is no electric field, and the molecular orientation is different from the first stable state in one electric field direction when an electric field is applied. It has a stable state ((1) in FIG. 4D), and further has a third molecular orientation stable state ((3) in FIG. 4D) different from the first and second stable states with respect to the other electric field direction. Means that. The present applicant applied for a liquid crystal electro-optical device utilizing the tri-stable state, that is, the tri-state, and is disclosed in JP-A-2-40625 and JP-A-2-15332.
No. 2 and JP-A No. 2-173724.

On the other hand, "commercial nematic liquid crystal"
The two-state liquid crystal does 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 used as a liquid crystal display, compared with the conventional nematic liquid crystal. The conventional type required a very complicated structure in which the driving method was an active matrix method 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 tri-state ferroelectric liquid crystal, the production process is simple and It is an epoch-making product that can be made larger and the manufacturing cost can be reduced. Another object of the present invention is to
The point is to provide a novel liquid crystal exhibiting this tri-state ferroelectricity.

[0007]

[Structure] The present invention has the general formula

[Chemical 10] [In the formula, R ₁ and R ₂ are an alkyl group having 4 to 18 carbon atoms, R ₃
Is an alkyl group or a haloalkyl group, X is O, COO,
OCO, CO or single bond, Y is COO, OCO, CH
₂ O, OCH ₂ or a single bond, Z is COO or O,

[Chemical 11] The cyclic group represented by and t indicate that at least one halogen atom is substituted. * Indicates optically active carbon. ] It represents with respect to the liquid crystal compound characterized by the above-mentioned. The haloalkyl group is CH ₂ F, C
HF ₂ , CF ₃ , C ₂ F ₅ , CClF ₂ , CCl ₃ , CF ₃ C
Although Cl _{2 and the} like can be mentioned, CF ₃ and C ₂ F ₅ are most preferable. Most preferably, t is F, followed by Cl,
The order is Br.

An example of a method for synthesizing the compound of the present invention will be shown. 4-
Benzyloxybenzoic acid halide and 1,1,1-trifluoro-2-alkanol are reacted in the presence of a catalyst in an organic solvent to give 1,1,1-trifluoro-2-alkyl 4-benzyloxybenzoate. (A) is obtained. Then, for example, in the presence of a Pd / C catalyst, the above (a) is hydrolyzed in an organic solvent to give 1,1,1-trifluoro-2-alkyl 4-hydroxybenzoate (b).
To synthesize. 4 "-alkyloxyterphenyl-4-
Carboxylic acid chloride and (b) are reacted in an organic solvent in the presence of a catalyst to give 4- (1,1,1-trifluoro-
2-Alkyloxycarbonyl) phenyl 4 ″ -alkyloxyterphenyl-4-carboxylate is obtained.

[0009]

【Example】

Example 1 Synthesis of 4- (1,1,1-trifluoro-2-octyloxycarbonyl) phenyl 4 ″ -n-decyloxyterphenyl-4-carboxylate

Embedded image (1) Synthesis of 1,1,1-trifluoro-2-octyl 4-benzyloxybenzoate

Embedded image 4-Benzyloxybenzoic acid chloride 4.3
g in 50 ml of methylene chloride, and then 2.9 of the optically active 1,1,1-trifluoro-2-octanol.
g A solution prepared by dissolving 0.6 g of dimethylaminopyridine and 1.7 g of triethylamine in 50 ml of methylene chloride was added little by little under ice cooling. The reaction mixture is returned to room temperature, reacted overnight, poured into ice water, extracted with methylene chloride, and the methylene chloride phase is washed successively with diluted hydrochloric acid, water, 1N sodium carbonate aqueous solution, and water, and dried over anhydrous magnesium sulfate. After drying, the solvent was distilled off to obtain a crude product. This was treated with silica gel chromatograph and recrystallized with ethanol to obtain 3.8 g of the objective compound. (2) 1,1,1-trifluoro-2-octyl 4-
Synthesis of hydroxybenzoate

[Chemical 14] The compound obtained in (1) was dissolved in 100 ml of methanol, 0.4 g of 10% supported Pd-carbon was added, and hydrogenolysis reaction was carried out in a hydrogen atmosphere to obtain 2.8 g of the target compound. (3) Synthesis of 4- (1,1,1-trifluoro-2-octyloxycarbonyl) phenyl 4 ″ -n-decyloxyterphenyl-4-carboxylate

[Chemical 15] After heating 2.0 g of 4 "-n-decyloxyterphenyl-4-carboxylic acid with an excess of thionyl chloride under reflux for 6 hours, unreacted thionyl chloride was distilled off to obtain 4" -n.
-Decyloxyterphenyl-4-carboxylic acid chloride was obtained. A solution prepared by dissolving the acid chloride in 50 ml of methylene chloride was added to 1,1,1-trifluoro-2-
A solution prepared by dissolving 1.0 g of octyl 4-hydroxybenzoate, 0.4 g of triethylamine and 0.1 g of dimethylaminopyridine in 50 ml of methylene chloride was gradually added under ice cooling and the reaction was carried out at room temperature overnight. Then, the reaction solution was poured into ice water and extracted with methylene chloride. The methylene chloride phase was washed with dilute hydrochloric acid, water, an aqueous solution of sodium carbonate, and water in this order, dried over anhydrous sodium sulfate, and then the solvent was distilled off. The crude product was obtained. This was purified by silica gel chromatography to obtain 1.3 g of the optically active target compound. To measure the phase transition point, the compound was recrystallized from absolute ethanol and further purified before use. The phase transition temperature (° C) of the target compound was determined by observing with a polarizing microscope using a hot stage.

[Table 1] Got However, S * (3) indicates an optically tristable liquid crystal phase. The infrared absorption spectrum of this target compound is shown in FIG. Example 2 Synthesis of 4- (1,1,1-trifluoro-2-octyloxycarbonyl) -4 ″ -octyloxyta-phenyl

[Chemical 16] After 1.6 g of 4 "-n-octyloxyterphenyl-4-carboxylic acid was heated under reflux with excess thionyl chloride for 6 hours, unreacted thionyl chloride was distilled off to give 4" -n.
-Octyloxyterphenyl-4-carboxylic acid chloride was obtained. A solution of the acid chloride in 50 ml of methylene chloride was added to 1,1,1-trifluoro-2-octano-
0.7 g, triethylamine 0.4 g and dimethylaminopyridine 0.1 g dissolved in methylene chloride 50 ml were gradually added under ice cooling and reacted at room temperature overnight. Then, the reaction solution was poured into ice water and extracted with methylene chloride. The methylene chloride phase was washed with dilute hydrochloric acid, water, an aqueous solution of sodium carbonate, and water in this order, dried over anhydrous sodium sulfate, and then the solvent was distilled off. The crude product was obtained. This was purified by silica gel chromatography to obtain 1.1 g of the optically active target compound. To measure the phase transition point, the compound was recrystallized from absolute ethanol and further purified before use. The phase transition temperature (° C) of the target compound was determined by observing with a polarizing microscope using a hot stage.

[Table 2] Got However, S * (3) indicates an optically tristable liquid crystal phase. The infrared absorption spectrum of the target compound is shown in FIG. Example 3 Synthesis of 4- (1,1,1-trifluoro-2-decyloxycarbonyl) -4 ″ -octyloxyterphenyl

[Chemical 17] Instead of the 1,1,1-trifluoro-2-octanol of Example 2, 1,1,1-trifluoro-2-decanol was used for the synthesis to obtain the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarization microscope.

[Table 3] However, S * (3) indicates an optically tristable liquid crystal phase. The infrared absorption spectrum of the target compound is shown in FIG. Example 4 Synthesis of 4- (1,1,1-trifluoro-2-octyloxycarbonyl) -4 ″ -decyloxyterphenyl

[Chemical 18] After heating 1.7 g of 4 "-n-decyloxyterphenyl-4-carboxylic acid under reflux with excess thionyl chloride for 6 hours, unreacted thionyl chloride was distilled off to give 4" -n.
-Decyloxyterphenyl-4-carboxylic acid chloride was obtained. To a solution prepared by dissolving the acid chloride in 50 ml of methylene chloride, 0.7 g of 1,1,1-trifluoro-2-octanol, 0.4 g of triethylamine and 0.1 g of dimethylaminopyridine were dissolved in 50 ml of methylene chloride. The mixture was gradually added under ice cooling and reacted at room temperature overnight.
Then, the reaction solution was poured into ice water and extracted with methylene chloride. The methylene chloride phase was washed with dilute hydrochloric acid, water, an aqueous solution of sodium carbonate, and water in this order, dried over anhydrous sodium sulfate, and then the solvent was distilled off. The crude product was obtained. This was purified by silica gel chromatography to obtain 1.0 g of the optically active target compound. To measure the phase transition point, the compound was recrystallized from absolute ethanol and further purified before use. The phase transition temperature (° C) of the target compound was determined by observing with a polarizing microscope using a hot stage.

[Table 4] Got However, S * (3) indicates an optically tristable liquid crystal phase. The infrared absorption spectrum of the target compound is shown in FIG. Example 5 Synthesis of 4- (2-octyloxycarbonyl) -4 ″ -octyloxyterphenyl

[Chemical 19] Instead of 1,1,1-trifluoro-2-octanol of Example 2, synthesis was carried out using optically active 2-octanol to obtain the desired product. The following phase transition temperature (° C.) was obtained by observing the hot stage with a polarization microscope.

[Table 5] The infrared absorption spectrum of the target compound is shown in FIG. Example 6 The liquid crystal compound 4- (1,1,1-trifluoro-2-) obtained in Example 2 was used in a liquid crystal cell having a rubbing-treated polyimide alignment film on an ITO electrode substrate and having a cell thickness of 1.6 μm.
A liquid crystal thin film cell was prepared by filling octyloxycarbonyl) -4 ″ -octyloxyterphenyl in an Isotropic phase. The prepared liquid crystal cell was applied to a polarizing microscope with a photomultiplier in which two polarizing plates were orthogonal to each other, and a voltage of 0V was applied. The liquid crystal cell is gradually cooled to the SA phase with a temperature gradient of 0.1 to 1.0 ° C. for 1 minute, and further cooled.
± 3 shown in FIG. 10 (a) in the temperature range of ˜80 ° C.
A triangular wave voltage of 0 V and 10 Hz is applied. From the relationship between the applied voltage and the transmittance at 109 ° C., the hysteresis as shown in FIG. 10B was obtained. The dark state is maintained from 0 to + V ₁ and the bright state is reached after a sharp rise at + V ₁ . +3
0 → + to V ₂ keeps the bright state, suddenly it becomes a dark state at + V _2. 0 → -V up to ₁ to keep the dark state, after a sharp rise in -V _1, become bright state. -30V → -V up to ₂ keeps the bright state, it becomes suddenly dark state at -V _2. When the applied voltage changed from + 30V to -30V, it was observed that the state changed to three states of bright → dark → bright accompanied by switching, confirming that there are three stable alignment states of liquid crystal molecules. did. The same S * is applied to the compounds of other examples.
The same effect was confirmed in the (3) phase.

[0010]

EFFECTS OF THE INVENTION 1. Among the optically active liquid crystal compounds of the present invention, those exhibiting a ferroelectric liquid crystallinity can be used for a liquid crystal display device or the like alone or as a mixture with another liquid crystal compound. Further, even those having a low liquid crystallinity can be mixed with other liquid crystal compounds to form a liquid crystal composition. 2. Further, among the optically active liquid crystal compounds of the present invention, S *
The antiferroelectric liquid crystal exhibiting the phase (3) has applications such as electro-optical devices, display devices, and switching elements utilizing the three states.

[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 a two-state liquid crystal actually synthesized so far.

FIG. 3 shows hysteresis of a three-state liquid crystal according to the present invention, and in each of FIGS. 1 to 3, the horizontal axis represents applied voltage and the vertical axis represents transmittance (%).

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

FIG. 5 shows an infrared absorption spectrum of the liquid crystal compound of Example 1 of the present invention. The vertical axis of the infrared absorption spectrum is the transmittance,
The horizontal axis indicates the wave number.

FIG. 6 shows an infrared absorption spectrum of the liquid crystal compound of Example 2 of the present invention.

FIG. 7 shows an infrared absorption spectrum of the liquid crystal compound of Example 3 of the invention.

FIG. 8 shows an infrared absorption spectrum of the liquid crystal compound of Example 4 of the present invention.

FIG. 9 shows an infrared absorption spectrum of the liquid crystal compound of Example 5 of the invention.

10 shows the hysteresis exhibited by the tri-state liquid crystal compound of Example 2 in Example 6, where (a) is the applied triangular wave voltage and (b) is the compound of Example 2 with respect to the applied triangular wave voltage. 3 shows the hysteresis of the change in the light transmittance of.

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI Technical indication C07C 69/76 Z 9279-4H 69/82 A 9279-4H 69/83 9279-4H 69/86 9279-4H 69 / 92 9279-4H C09K 19/20 6742-4H 19/30 6742-4H G02F 1/13 500 (72) Inventor Noriko Yamakawa 3-5 Kasumigaseki, Chiyoda-ku, Tokyo Showa Ciel Oil Co., Ltd.

Claims (9)

[Claims] 1. A general formula: [In the formula, R ₁ and R ₂ are an alkyl group having 4 to 18 carbon atoms, R ₃
Is an alkyl group or a haloalkyl group, X is O, COO,
OCO, CO or a single bond, Y is COO, OCO, C
H ₂ O, OCH ₂ or a single bond, Z is COO or O, The cyclic group represented by and t indicate that at least one halogen atom is substituted. * Indicates optically active carbon. ] The optically active liquid crystal compound represented by these. 2. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'is CF ₃ or C ₂ F _5, X' is O, COO, CO or a single bond, t indicates that the halogen atom is substituted at least one or more. * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 3. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'is CF ₃ or C ₂ F _5, X' represents O, COO, CO or a single bond. * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 4. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'is CF ₃ or C ₂ F _5, X' represents O, COO, CO or a single bond. * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 5. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'represents CF ₃ or C ₂ F ₅ . * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 6. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ ′ represents CF ₃ or C ₂ F ₅ , and t represents that at least one halogen atom is substituted. * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 7. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'represents CF ₃ or C ₂ F ₅ . * Indicates optically active carbon. ] An optically active antiferroelectric liquid crystal compound represented by the following formula. 8. A general formula: [Wherein R ₁ ′ and R ₂ ′ are alkyl groups having 4 to 18 carbon atoms,
R ₃ 'represents CH ₃ . * Indicates optically active carbon. ] The optically active liquid crystal compound represented by these. 9. A liquid crystal composition comprising one or more kinds of the optically active compound represented by claim 1.