JPH09216851A - Liquid crystal having rapid response and liquid crystal composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound having optically active positions of CF3 , whose number of carbon at the chiral side is 3, enabling a wide improvement in response speed in various antiferroelectric liquid crystal compositions and useful for display materials, etc. SOLUTION: A compound of the formula [ring A to ring D are each a phenyl ring which may be substituted with a halogen atom; R is a 8-16C alkyl which may have a double bond; (m)+(n)=1, 2; (p)+(q)=1, 2; X is COO, CO, OCO or a single bond; the mark * indicates an optically active part], e.g. 4-(1,1,1- trifluoro-2-pentyloxycarbonyl)phenyl-4'-n-nonylbiphenyl-4-carboxylate. Further, the compound may be obtained e.g. by using (+)-1,1,1-trifluoro-2-pentanol as a starting material and through the preparation of (+)-1,1,1-trifluoro-2-pentyl-4- hydroxybenzoate by esterification, hydrogenation, etc.

Description

Detailed Description of the Invention

[0001]

The present invention is characterized in that the optically active site, which has been difficult to synthesize conventionally, is CF ₃ , the number of carbon atoms on the chiral side is 3, and that it has a faster response speed than conventional compounds. And a ferroelectric liquid crystal compound and a liquid crystal composition containing them.

[0002]

2. Description of the Related Art Liquid crystal display devices are 1) low-voltage operable 2).
Since it has excellent features such as low power consumption, 3) thin display, and 4) light receiving type, TN method, STN method,
A guest-host method has been developed and put to practical use. However, a nematic liquid crystal that is widely used at present has a response speed of several mse.
It has a drawback as slow as c to several tens of msec, and is subject to various restrictions in application. In order to solve these problems, an STN method and an active matrix method using a thin layer transistor have been developed, but the STN type display element has excellent display quality such as display contrast and viewing angle. However, there are problems that high accuracy is required for controlling the cell gap and the tilt angle and that the response is rather slow. For this reason, the development of a new liquid crystal display system having excellent responsiveness has been demanded, and the development of a ferroelectric liquid crystal capable of realizing an ultrahigh-speed device having an extremely short optical response time on the order of μsec has been attempted. Ferroelectric liquid crystal has 1
In 975, DOBAMBC (p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate) was first synthesized by Meyer et al. (Le Jour).
nal de Physique, vol. 36, 1975, L
-69). In addition, 1980, Clark and Laga
Since the characteristics of display devices such as sub-microsecond high-speed response of DOBAMBC and memory characteristics have been reported by WALL, ferroelectric liquid crystals have attracted great attention [N. A. Clark, et al. , Appl. P
hys. Lett. 36.899 (1980)]. However, their method has many technical problems for practical use, and in particular, there are few materials that exhibit a ferroelectric liquid crystal phase at room temperature, and they are effective and practical for controlling the alignment of liquid crystal molecules that are indispensable for display displays. No specific method was established. Since this report, various attempts have been made from both sides of liquid crystal materials / devices, prototype display devices utilizing switching between twisted two states have been produced, and high-speed electro-optical devices using the same have been disclosed, for example, in JP-A-56-107216. However, high contrast and proper threshold characteristics have not been obtained. From such a viewpoint, other switching schemes have been searched, and a transient scattering scheme has been proposed. Then, in 1988, the present inventors reported a three-state switching method of a liquid crystal having a tristable state [A. D. L. Chandani, T .; Hagiwar
a, Y. Suzuki et al. , Japan. J.
ofAppl. Phys. , 27, (5), L729-
L732 (1988)]. 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. It is configured to apply a voltage for forming an electric field to the first and second electrode substrates,
When a voltage is applied as the triangular wave shown in FIG. 1A, the ferroelectric liquid crystal has a first stable state (1 in FIG. 1D) with no electric field, and the electric field is applied as shown in FIG. 1D. Occasionally, a molecular orientation has a second stable state (2 in FIG. 1D) different from the first stable state with respect to one electric field direction,
Furthermore, it means having a third molecular orientation stable state (3 in FIG. 1D) different from the first and second stable states with respect to the other electric field direction. Regarding the liquid crystal electro-optical device utilizing the tri-stable state, that is, the tri-state, the applicant of the present application filed as Japanese Patent Application No. 63-70212 and is disclosed in Japanese Patent Laid-Open No. 2-153322. The characteristics of the antiferroelectric liquid crystal exhibiting the tristable state will be described in more detail.
Clark-Lagawal
In the surface-stabilized ferroelectric liquid crystal device proposed by l), the ferroelectric liquid crystal molecules in the S ^* C phase are shown in FIG.
As shown in (b), it shows two stable states that are uniformly oriented in one direction. Depending on the direction of the applied electric field, it is stabilized in either one of the states, and the state is maintained even when the electric field is cut off. However, in reality, the alignment state of the ferroelectric liquid crystal molecules shows a twisted two state in which the director of the liquid crystal molecules is twisted, or a chevron structure in which the layers are bent in a V shape. In the chevron layer structure, the switching angle becomes small, which causes low contrast, which is a major obstacle to practical use. On the other hand, in the S ^* (3) phase in which the “anti” ferroelectric liquid crystal exhibits a tristable state, in the above-mentioned liquid crystal electro-optical device, when there is no electric field, the molecules are reversed in each adjacent layer as shown in FIG. The dipoles of the liquid crystal molecules cancel each other. Therefore, the spontaneous polarization is canceled in the entire liquid crystal layer. The liquid crystal phase exhibiting this molecular arrangement corresponds to 1 in FIG. 1D. further,
When a voltage sufficiently higher than the threshold value of (+) or (−) is applied, the liquid crystal molecules shown in FIGS. 3B and 3C are aligned in parallel in the same direction. In this state, the dipoles of the molecules are also aligned in the same direction, so that spontaneous polarization occurs and a ferroelectric phase is formed. That is, in the S ^* (3) phase of the “anti” ferroelectric liquid crystal, the “anti” ferroelectric phase when there is no electric field and the two ferroelectric phases depending on the polarity of the applied electric field are stable, and the “anti” ferroelectric liquid crystal is stable. Switching between the three stable states is performed with a DC threshold value between the phase and the two ferroelectric phases. Due to the change in the liquid crystal molecule arrangement accompanying the switching, the light transmittance changes in a double hysteresis shown in FIG. As shown in FIG. 4A, a memory effect can be realized by applying a bias voltage to this double hysteresis and further superimposing a pulse voltage. Further, by applying an electric field, the layer of the ferroelectric phase is stretched to form a bookshelf structure. On the other hand, the third stable state “anti” ferroelectric phase has a similar bookshelf structure. Since the layer structure switching by the application of the electric field gives a dynamic shear to the liquid crystal layer, alignment defects are improved during driving, and good molecular alignment can be realized. In the "anti-" ferroelectric liquid crystal, image display is performed by using both the hysteresis on the plus side and the hysteresis on the minus side alternately, so that an afterimage phenomenon of an image due to accumulation of an internal electric field based on spontaneous polarization can be prevented. As mentioned above,
"Anti" ferroelectric liquid crystal is a very useful liquid crystal compound that can 1) achieve high-speed response, 2) achieve high contrast and wide viewing angle, and 3) achieve good alignment characteristics and memory effect. Regarding the liquid crystal phase showing the tristable state of "anti" ferroelectric liquid crystal, 1) A. D. L. Chandani e
tal., Japan J. Appl. Phys., 2
8 , L-1265 (1989), 2) H.E. Orihar
a et al., JapanJ. Appl. Phys.,
29 , L-333 (1990),
Due to its "anti" ferroelectric properties, the S ^* CA phase (Antive
rroelectric Sectic C ^* phase). The present inventors have defined this liquid crystal phase as the S ^* (3) phase because it switches between the three stable states. A liquid crystal compound having an “anti” ferroelectric phase S ^* (3) in a phase series showing a tristable state is disclosed in Japanese Patent Application Laid-Open No. 1-3163 of the present application.
67, JP-A-1-316372, and JP-A-1-316.
No. 339, No. 2-28128, and No. 1-213390 of Ichihashi et al., And as a liquid crystal electro-optical device utilizing a tristable state, the present applicant discloses in Japanese Patent Application Laid-Open No. 2-4.
No. 0625, JP-A-2-153322, and JP-A2-1.
A new proposal is made in No. 73724. "Anti"
When applying ferroelectric liquid crystals to liquid crystal displays, 1)
It is difficult to satisfy all of the operating temperature range, 2) response speed, 3) spontaneous polarization, 4) hysteresis characteristics, etc. with a single liquid crystal, and it is usually prepared as a dozen or more kinds of mixed liquid crystals. Conventionally, an optically active site having CF ₃ has a carbon number of 4 on the chiral side even though it has the shortest carbon number, and thus it is possible to further increase the response speed required for a ferroelectric liquid crystal material and an antiferroelectric liquid crystal material. For this purpose, it is necessary to develop a ferroelectric liquid crystal compound and an antiferroelectric liquid crystal compound in which the optically active site is CF ₃ and the number of carbon atoms on the chiral side is 3.

[0003]

The object of the present invention is to provide a conventional ferroelectric liquid crystal compound and an antiferroelectric liquid crystal compound having an optically active site of CF ₃ and having 3 carbon atoms on the chiral side, and at room temperature. Another object of the present invention is to provide a ferroelectric liquid crystal compound or an antiferroelectric liquid crystal compound having a characteristic that the response speed is faster than that, and a composition containing them.

[0004]

Means for Solving the Problems In order to achieve the above object, the present inventors have proposed a ferroelectric liquid crystal compound having an optically active site of CF ₃ and having 3 carbon atoms on the chiral side, and an antiferroelectric liquid crystal. As a result of earnest efforts on the synthesis of the compound, the inventors have found a ferroelectric liquid crystal compound and an antiferroelectric liquid crystal compound exhibiting a higher response speed at around room temperature than conventional liquid crystal compounds, and completed the present invention. is there.

That is, one of the present inventions is represented by the following general formula (1)

Embedded image (In the formulae, ring A, ring B, ring C and ring D represent a group independently selected from the group consisting of a phenyl ring optionally substituted with a halogen atom, and R represents a group having 8 to 16 carbon atoms. Represents an alkyl group which may contain a double bond of
Is 1 or 2, p + q is 1 or 2, X is O, C
OO, CO, OCO or a single bond, and * represents an optically active site).

The liquid crystal compound is represented by the following general formula (2)

Embedded image (In the formula, ring A, ring B and ring C represent a group independently selected from the group consisting of a phenyl ring optionally substituted with a halogen atom, m + n is 1 or 2, and R is the number of carbon atoms. Represents an alkyl group which may contain a double bond from 8 to 16, X represents O, COO, CO, OCO or a single bond, and * represents an optically active site). preferable.

Another aspect of the present invention relates to a liquid crystal composition containing at least one liquid crystal compound according to claim 1 or 2.

Examples of compounds of the invention are listed in the table below.

[Table 1]

[Table 2]

[Table 3] ^{* 1} Ph: Phenyl ^{* 4} 3'FPh: 3'-Fluorophenyl ^{* 2} 3FPh: 3-Fluorophenyl ^{* 5-} : Single bond ^{* 3} 2FPh: 2-Fluorophenyl

Regarding the liquid crystal compound of the present invention, R
Those having 10 carbon atoms show ferroelectricity (see Example 2), and others having R 9 carbon atoms (see Example 1) and 11 (see Example 3) show antiferroelectricity. Also shows. Therefore, the liquid crystal compounds of the present invention can be blended with each other or with other liquid crystal compounds to be used as a ferroelectric liquid crystal composition or an antiferroelectric liquid crystal composition.

A method for synthesizing 1,1,1-trifluoro-2-pentanol in which the alkyl group on the optically active side has 3 carbon atoms is shown below. 83 g of scraped magnesium (3.
4 mol) n-propyl bromide 400 g (3.3 mo)
A solution of l) in 1000 ml of ether was added dropwise over 1.5 hours to prepare a Grignard reagent. Then 416 g (2.93 mol) of ethyl trifluoroacetate in ether 10
The Grignard reagent prepared above was added dropwise to the 00 ml solution under ice cooling, and the reaction was carried out for 4 hours while maintaining the solution temperature at 5 ° C or lower. The reaction solution was quenched into 800 ml of 12N hydrochloric acid and 800 g of ice, the ether layer was separated, and washed with saturated aqueous sodium hydrogen carbonate and water. Approximately 2500 ml of the obtained 1,1,1-trifluoro-2-pentanone (i) ether solution was added to 20 ml of water.
0 ml was added, and a solution of 29 g of sodium borohydride in 100 ml of water was added dropwise over 30 minutes while cooling to 35 ° C or lower. After the dropping, the mixture was stirred at room temperature for 2 hours. The ether layer was separated from the reaction solution, washed with a saturated saline solution, dehydrated with anhydrous magnesium sulfate, and then the ether was distilled off to obtain a crude oil containing 1,1,1-trifluoro-2-pentanol (ii) (497 g). Got 497 g of crude oil containing 1,1,1-trifluoro-2-pentanol, 275 g of acetyl chloride (3.50 m
ol) and 1500 ml of methylene chloride were uniformly mixed, and 316 g (4.0 mol) of pyridine was added dropwise over 1.5 hours while stirring under ice cooling. After dropping, react at room temperature for 3 hours,
It was quenched with a mixture of 500 ml of 12N hydrochloric acid and 500 g of ice. The methylene chloride layer was washed with water, washed with saturated sodium bicarbonate water, and then washed with water repeatedly. After dehydration with anhydrous magnesium sulfate, methylene chloride was distilled off under atmospheric pressure, and then the distillation temperature was 1 by precision distillation.
A fraction 448 g containing 1,1,1-trifluoro-2-pentyl acetate (iii) at 15 to 123 ° C. was obtained (yield from ethyl trifluoroacetate 79.8%). Next, 445 g of 1,1,1-trifluoro-2-pentyl acetate, 45 g of lipase MY, and 4500 ml of water were mixed, and the mixture was stirred for 22 hours in a constant temperature bath at 40 ° C. To remove the used lipase MY, adsorption was performed using Celite to obtain 1500 ml of extract. The extract was further extracted with methylene chloride, washed with saturated aqueous sodium hydrogen carbonate and saturated brine,
After dehydration with anhydrous magnesium sulfate, methylene chloride was distilled off under normal pressure. This concentrate was separated into R form and S form using column chromatography, concentrated, and 111 g of (+)-1,1,1-trifluoro-2-pentanol (iv) (optical purity 97.4%). ee, yield 33.2%). The enzyme separation, column chromatography and other purification methods in the above method can be replaced by known methods.

(+)-1,1,1-prepared by the above method
By using trifluoro-2-pentanol as a starting material and a conventional method (esterification reaction with 4-benzyloxybenzoic acid chloride, column separation purification, hydrogenation using palladium carbon, column separation purification), (+) -1,
Prepare 1,1-trifluoro-2-pentyl-4-hydroxybenzoate (v). Moreover, 4'-alkyl-4-biphenylcarboxylic acid chloride (vi) is prepared by reacting 4'-alkyl-4-biphenylcarboxylic acid with a chlorinating agent such as thionyl chloride. The above-prepared 1,1,1-trifluoro-2-pentyl-4-
Hydroxybenzoate and 4'-alkyl-4-biphenylcarboxylic acid chloride in methylene chloride as a solvent, triethylamine (hereinafter abbreviated as TEA) and dimethylaminopyridine (hereinafter abbreviated as DMAP) as a catalyst, and at room temperature under a nitrogen atmosphere overnight or more. React. The reaction solution is washed with a hydrochloric acid solution, dehydrated with anhydrous magnesium sulfate, and methylene chloride is distilled to obtain a crude product. The crude product was separated and purified using silica gel with a mixed solution of hexane / ethyl acetate to obtain (+)-4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-
4'-alkylbiphenyl-4-carboxylate (vi
get i). It can be further purified using ethanol. Further, the separation and purification of the crude product, the ester synthesis, and the recrystallization of the liquid crystal can be replaced by known methods other than the methods described above. Further, not only the (+) body but also the (-) body can be manufactured by the same method.

[0012]

Embedded image

The method of measuring the response speed in the present invention is as follows. That is, the compound was injected into a cell having a thickness of 2 μm and made of glass with a transparent electrode, which was coated with polyimide and subjected to rubbing treatment, and the cell for measuring liquid crystal physical properties was set on a hot stage, and the two polarizing plates were made orthogonal to each other. It was placed in a polarization microscope with a photomultiplier so as to have a dark field in the absence of an electric field. When the liquid crystal in the cell is in the antiferroelectric phase, the response time τ can be determined from the change in the relative transmittance of light when a rectangular wave of ± 50 V as shown in FIG. 5 is applied to the cell. τ is from the state of the ferroelectric phase (at the end of the rectangular wave voltage on the negative side) to the state of the next ferroelectric phase via the state of the antiferroelectric phase (the relative transmittance is 90% when the rectangular wave voltage on the positive side is applied. When the value reaches (), the unit is μsec. It is.

[0014]

The present invention will be described below with reference to examples.
The present invention is not limited to this.

Example 1 The following formula

[Chemical 6] Synthesis of 4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-4′-n-nonylbiphenyl-4-carboxylate represented by (+)-1,1,1-trifluoro- Using 2.00 g (13.4 mmol) of 2-pentanol as a starting material, a conventional method (esterification reaction with 4-benzyloxybenzoic acid chloride, column separation purification, hydrogenation using palladium carbon, column separation purification) , 1,1,1-
Prepare 2.54 g (9.8 mmol, 73%) of trifluoro-2-pentyl-4-hydroxybenzoate. In addition, by reacting 4'-nonyl-4-biphenylcarboxylic acid with a chlorinating agent such as thionyl chloride,
Prepare 4'-nonyl-4-biphenylcarboxylic acid chloride. 1,1,1-trifluoro-2-prepared above
Pentyl-4-hydroxybenzoate 0.20 g
(0.8 mmol) and 4'-nonyl-4-biphenylcarboxylic acid chloride 0.24 g (0.7 mmol) in methylene chloride as a solvent, TEA 0.07 g (0.7 mmo)
1) and DMAP 0.03 g (0.2 mmol) as a catalyst are reacted overnight or more at room temperature under a nitrogen atmosphere. The reaction solution is washed with a hydrochloric acid solution, dehydrated with anhydrous magnesium sulfate, and methylene chloride is distilled to obtain a crude product. This crude product was separated and purified on silica gel with a mixed solution of hexane / ethyl acetate to give 4- (1,1,1-
This gives 0.36 g (83%) of trifluoro-2-pentyloxycarbonyl) phenyl-4′-n-nonylbiphenyl-4-carboxylate. It can be further purified using ethanol.

¹ H-NMR of this compound (T in CDCl ₃
MS standard, δ value ppm) is 8.3 to 7.1 (m, 12)
H), 5.7-5.5 (m, 1H), 2.8-2.6.
(T, 2H), 2.1 to 0.8 (m, 24H). Also, the above compound was injected into a cell having a thickness of 2 μm and made of glass with a transparent electrode, which was coated with polyimide and subjected to rubbing treatment, and Table 4 shows the phase transition temperatures observed by a polarization microscope with a hot stage. This compound was a ferroelectric liquid crystal compound and an anti-dielectric liquid crystal compound. Table 4 also shows the response speed at 50 ° C.

Example 2 The following formula

Embedded image Synthesis of 4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-4′-n-decylbiphenyl-4-carboxylate represented by 1,1,1 in the same manner as in Example 1 -Trifluoro-2
-Prepare pentyl-4-hydroxybenzoate.
Further, by reacting 4'-decyl-4-biphenylcarboxylic acid with a chlorinating agent such as thionyl chloride, 4'-
-Prepare decyl-4-biphenylcarboxylic acid chloride. 0.20 g (0.80) of the 1,1,1-trifluoro-2-pentyl-4-hydroxybenzoate prepared above
mmol) and 0.25 g (0.7 mmol) of 4'-decyl-4-biphenylcarboxylic acid chloride in methylene chloride as a solvent, and 0.07 g (0.7 mmol) of TEA and D.
Using MAP 0.03 g (0.2 mmol) as a catalyst, the reaction is carried out overnight at room temperature under a nitrogen atmosphere. The reaction solution is washed with a hydrochloric acid solution, dehydrated with anhydrous magnesium sulfate, and methylene chloride is distilled to obtain a crude product. The crude product was separated and purified on silica gel with a mixed solution of hexane / ethyl acetate to give 4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-4 '.
-N-decylbiphenyl-4-carboxylate 0.3
7 g (91%) are obtained. It can be further purified using ethanol.

¹ H-NMR of this compound (T in CDCl ₃
MS standard, δ value ppm) is 8.3 to 7.1 (m, 12)
H), 5.7-5.5 (m, 1H), 2.8-2.6.
It was (t, 2H) and 2.1-0.8 (m, 26H). Also, the above compound was injected into a cell having a thickness of 2 μm and made of glass with a transparent electrode, which was coated with polyimide and subjected to rubbing treatment, and Table 4 shows the phase transition temperatures observed by a polarization microscope with a hot stage. This compound was a ferroelectric liquid crystal compound. Table 4 also shows the response speed at 50 ° C.

Example 3 The following formula

Embedded image Synthesis of 4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-4′-n-undecylbiphenyl-4-carboxylate represented by 1,1,1 in the same manner as in Example 1 1-trifluoro-2
-Prepare pentyl-4-hydroxybenzoate.
Further, by reacting 4′-undecyl-4-biphenylcarboxylic acid with a chlorinating agent such as thionyl chloride,
4'-Undecyl-4-biphenylcarboxylic acid chloride is prepared. 1,1,1-trifluoro-prepared above
2-pentyl-4-hydroxybenzoate 0.20 g
(0.8 mmol) and 4'-undecyl-4-biphenylcarboxylic acid chloride 0.26 g (0.7 mmol) in methylene chloride as a solvent, TEA 0.07 g (0.7 m)
(mol) and 0.03 g (0.2 mmol) of DMAP as a catalyst are reacted overnight or more at room temperature under a nitrogen atmosphere. The reaction solution is washed with a hydrochloric acid solution, dehydrated with anhydrous magnesium sulfate, and methylene chloride is distilled to obtain a crude product. The crude product was separated and purified using silica gel with a mixed solution of hexane / ethyl acetate to give 4- (1,1,
0.37 g (89%) of 1-trifluoro-2-pentyloxycarbonyl) phenyl-4′-n-undecylbiphenyl-4-carboxylate are obtained. It can be further purified using ethanol.

¹ H-NMR of this compound (T in CDCl ₃
MS standard, δ value ppm) is 8.3 to 7.1 (m, 12)
H), 5.7-5.5 (m, 1H), 2.8-2.6.
It was (t, 2H) and 2.1-0.8 (m, 28H). Also, the above compound was injected into a cell having a thickness of 2 μm and made of glass with a transparent electrode, which was coated with polyimide and subjected to rubbing treatment, and Table 4 shows the phase transition temperatures observed by a polarization microscope with a hot stage. This compound was a ferroelectric liquid crystal compound and an antiferroelectric liquid crystal compound. Table 4 also shows the response speed at 50 ° C.

[0021]

[Table 4]

Example 4 Compound 4- (1,1,1-trifluoro-2) of Example 3
-Pentyloxycarbonyl) phenyl-4'-n-undecylbiphenyl-4-carboxylate

Embedded image And 4- (2-octyloxycarbonyl) phenyl-
4'-n-nonyloxy-2-fluorobiphenyl-4
-Carboxylate

Embedded image Table 6 shows the response speeds at 50 ° C., 30 ° C. and 20 ° C. of the antiferroelectric liquid crystal composition in which and were mixed at a ratio of 70% by weight and 30% by weight.

Example 5 The following formula

Embedded image Synthesis of 4- (1,1,1-trifluoro-2-pentyloxycarbonyl) phenyl-4- (10-undecenoyloxy) phenyl-4-carboxylate represented by 1 in the same manner as in Example 1 , 1,1-trifluoro-2
-Prepare pentyl-4-hydroxybenzoate.
Further, by reacting 4- (10-undecenoyloxy) benzoic acid with a chlorinating agent such as thionyl chloride,
4- (10-Undecenoyloxy) benzoic acid chloride is prepared. 1,1,1-trifluoro-prepared above
2-pentyl-4-hydroxybenzoate 0.2 g
(0.8 mmol) and 4- (10-undecenoyloxy) benzoic acid chloride 0.23 g (0.7 mmol) using methylene chloride as a solvent, TEA 0.07 g (0.7 m)
(mol) and 0.03 g (0.2 mmol) of DMAP as a catalyst are reacted overnight or more at room temperature under a nitrogen atmosphere. The reaction solution is washed with a hydrochloric acid solution, dehydrated with anhydrous magnesium sulfate, and methylene chloride is distilled to obtain a crude product. The crude product was separated and purified using silica gel with a mixed solution of hexane / ethyl acetate to give 4- (1,1,
0.30 g (77%) of 1-trifluoro-2-pentyloxycarbonyl) phenyl-4- (10-undecenoyloxy) phenyl-4-carboxylate is obtained.
It can be further purified using ethanol.

¹ H-NMR of this compound (T in CDCl ₃
MS standard, δ value ppm) is 8.3 to 6.9 (m, 8)
H), 5.9 to 5.7 (m, 2H), 5.7 to 5.5.
(M, 1H), 5.1-4.9 (dd, 2H), 4.1
-3.9 (t, 2H), 2.2-2.0 (q, 2H),
It was 2.0-0.8 (m, 21H). Further, the above compound was injected into a cell having a thickness of 2 μm, which was made of glass with a transparent electrode and which was coated with polyimide and subjected to rubbing treatment, and the phase transition temperature by observation with a polarizing microscope with a hot stage was as follows. This compound was an antiferroelectric liquid crystal compound that exhibited antiferroelectricity only when the temperature was lowered.

[Table 5]

Comparative Example 1 The following formula

Embedded image A glass with a transparent electrode obtained by coating a 4- (1,1,1-trifluoro-2-hexyloxycarbonyl) phenyl-4′-n-undecylbiphenyl-4-carboxylate represented by Table 4 shows the phase transition temperatures observed by a polarizing microscope with a hot stage after injection into a cell having a thickness of 2 μm. Table 4 also shows the response speed at 50 ° C.

Comparative Example 2 4- (1,1,1-trifluoro-2-hexyloxycarbonyl) phenyl-4'-n-undecylbiphenyl-4-carboxylate

Embedded image And 4- (2-octyloxycarbonyl) phenyl-
4'-n-nonyloxy-2-fluoro-biphenyl-
4-carboxylate

Embedded image Table 6 shows the response speeds at 50 ° C., 30 ° C. and 20 ° C. of the antiferroelectric liquid crystal composition in which 70% by weight and 30% by weight were mixed.

[0027]

[Table 6]

Example 6 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 7 shows the response speed in the above.

Comparative Example 3 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 7 shows the response speed in the above.

[0030]

[Table 7]

Example 7 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 8 shows the response speed in the above.

Comparative Example 4 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 8 shows the response speed in the above.

[0033]

[Table 8]

Example 8 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 9 shows the response speed in the above.

Comparative Example 5 The following composition

Embedded image Was injected into a cell with a thickness of 2 μm made of glass with a transparent electrode which was coated with polyimide and subjected to rubbing treatment, and was measured using a polarization microscope with a hot stage at 60 ° C. and 50 ° C.
Table 9 shows the response speed in the above.

[0036]

[Table 9]

[0037]

[Effect] (1) Comparing Example 6 with Comparative Example 3, by adding the antiferroelectric liquid crystal compound of Example 3 to the composition having the CF ₃ -based optically active site as in Comparative Example 3, In particular,
It was confirmed that by adding 30% by weight of the antiferroelectric liquid crystal compound of Example 3 (Example 6), the response speed (μsec) at 60 ° C. or 50 ° C. was lowered by 8 to 12%. (2) Comparing Example 7 with Comparative Example 4, a composition in which the antiferroelectric liquid crystal compound of Example ₃ was mixed with the optically active site of CF ₃ system and CH ₃ system as in Comparative Example 4 was obtained. By blending, specifically, by adding 30 wt% of the antiferroelectric liquid crystal compound of Example 3 (Example 7), 60 ° C.
It was also confirmed that the response speed (μsec) at 50 ° C. decreased by 4 to 10%. (3) Comparing Example 8 and Comparative Example 5, the antiferroelectric liquid crystal compound of Example 3 has the optically active sites of CF ₃ system, CH ₃ system and antiferroelectric liquid crystal compound as in Comparative Example 5. By adding the compound to the composition in which the compounds are mixed, specifically, by adding 5% by weight of the antiferroelectric liquid crystal compound of Example 3 (Example 8), the response at 60 ° C. or 50 ° C. It was confirmed that the speed (μsec) was reduced by 2 to 5%. (4) From (1), (2), and (3), the optically active site is C
It was confirmed that by adding an antiferroelectric liquid crystal compound having 3 carbon atoms on the chiral side in F ₃ , the response speed of various antiferroelectric liquid crystal compositions was significantly improved. In other words, by adding an antiferroelectric liquid crystal compound having an optically active site of CF ₃ and having 3 carbon atoms on the chiral side, the response speed indispensable for a display material using an antiferroelectric liquid crystal material is greatly improved. You can see that it was done.

[Brief description of drawings]

1 (A) shows an applied triangular wave, (B) shows a commercially available nematic liquid crystal, (C) shows a two-state liquid crystal, and (D) shows a tristable state liquid crystal. .

FIG. 2 shows two stable alignment states of a ferroelectric liquid crystal molecule proposed by Clark / Ragaval.

FIG. 3A shows three stable alignment states of the “anti” ferroelectric liquid crystal molecules of the present invention. (B) shows three-state switching corresponding to each of (a), (b), and (c) of A and a change in liquid crystal molecule alignment.

FIG. 4 is an applied voltage-light transmittance characteristic diagram showing that the “anti” ferroelectric liquid crystal molecules change their light transmittance by drawing a double hysteresis with respect to an applied voltage.

FIG. 5A shows a relationship between applied voltage and time, and FIG.
Is a graph showing a response state of liquid crystal molecules when the applied voltage is applied.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tadaaki Isozaki 3-25 Kasumigaseki, Chiyoda-ku, Tokyo Akira Shell Oil Co., Ltd.

Claims (3)

[Claims] 1. The following general formula (1): (In the formulae, ring A, ring B, ring C and ring D represent a group independently selected from the group consisting of a phenyl ring optionally substituted with a halogen atom, and R represents a group having 8 to 16 carbon atoms. Represents an alkyl group which may contain a double bond of
Is 1 or 2, p + q is 1 or 2, X is O, C
A liquid crystal compound represented by OO, CO, OCO or a single bond, and * represents an optically active site. 2. The following general formula (2): (In the formula, ring A, ring B and ring C represent a group independently selected from the group consisting of a phenyl ring optionally substituted with a halogen atom, m + n is 1 or 2, and R is the number of carbon atoms. Represents an alkyl group which may contain a double bond from 8 to 16, X represents O, COO, CO, OCO or a single bond, and * represents an optically active site). 3. A liquid crystal composition comprising at least one liquid crystal compound represented by claim 1 or 2.