JPH03184965A - Optically active liquid crystal compound, liquid crystal composition containing the same, and liquid crystal element using the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a novel liquid crystal compound, a liquid crystal composition impregnating the same, and a liquid crystal element using the same, and more specifically, relates to a novel liquid crystal compound that has improved response characteristics to an electric field. The present invention relates to a novel liquid crystal composition, and a liquid crystal element using the same for use in liquid crystal display elements, liquid crystal light shutters, and the like.

[Conventional technology]

Conventionally, liquid crystals have been applied as electro-optical elements in various fields. Most of the liquid crystal elements currently in practical use are, for example, M, 5chadt and W, He1frich! “Applied Physics Letters”
Physics Letters”) VO, 18, N
(14 (1971°2.15) P, 127-128 “Voltage Dependent Optical
Activity of a Twist
d Nematicliquid Crystal1
T N (T w i s t e dN
It uses a liquid crystal of the matic) type.

These are based on the dielectric alignment effect of liquid crystals, and utilize the effect that the average molecular axis direction is oriented in a specific direction due to the dielectric anisotropy of liquid crystal molecules due to an applied electric field. The optical response speed limit of these devices is said to be milliseconds, which is too slow for many applications. On the other hand, for application to large flat displays, driving by a simple matrix method is the most promising in terms of cost, productivity, etc. In the simple matrix method, an electrode configuration is adopted in which a scanning electrode group and a signal electrode group are arranged in a matrix.
To drive this, a time-division drive method is adopted in which address signals are selectively and periodically applied to the scanning electrode group, and predetermined information signals are selectively applied in parallel to the signal electrode group in synchronization with the address signal. has been done.

However, when the above-mentioned TN type liquid crystal is adopted as an element of such a driving method, there is a region where the scanning electrode is selected and the signal electrode is not selected, or a region where the scanning electrode is not selected and the signal electrode is selected (so-called " A finite electric field is also applied to the half-selected point.

If the difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large, and the voltage threshold required to align the liquid crystal molecules perpendicular to the electric field is set to an intermediate voltage value,
Although the display element operates normally, the number of scanning lines (N
), the time during which an effective electric field is applied to one selected point (duty ratio) while scanning the entire screen (one frame) decreases at a rate of 1/N.

For this reason, when repeated scanning is performed, the effective voltage difference between selected points and non-selected points becomes smaller as the number of scanning lines increases, resulting in a decrease in image contrast and crosstalk. This is a drawback that is difficult to avoid.

This phenomenon is caused by liquid crystals that do not have bistability (the stable state is when the liquid crystal molecules are aligned horizontally with respect to the electrode surface, and they are aligned vertically only while an electric field is effectively applied). )
This is essentially an unavoidable problem that arises when driving using the temporal accumulation effect (that is, repeatedly scanning).

In order to improve this point, voltage averaging method, dual-frequency driving method, multiple matrix method, etc. have already been proposed, but all of these methods are insufficient, and it is necessary to increase the screen size and density of display elements. Currently, the number of scanning lines has reached a plateau due to the inability to increase the number of scanning lines sufficiently.

To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices has been proposed by Clark (C1a
rk) and Lagerwall (JP-A-56-107216, US Pat. No. 4,367,924, etc.).

Chiral smectic C is generally used as a bistable liquid crystal.
A ferroelectric liquid crystal having a phase (SmC* phase) or an H phase (SmH* phase) is used.

This ferroelectric liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state in response to an electric field, and therefore is different from the optical modulation element used in the above-mentioned TN type liquid crystal. Differently, for example, the liquid crystal is oriented in a first optically stable state with respect to one electric field vector, and the liquid crystal is oriented in a second optically stable state with respect to the other electric field vector. Further, this type of liquid crystal has a property (bistability) of taking one of the above two stable states in response to an applied electric field and maintaining that state when no electric field is applied.

In addition to the above-mentioned feature of bistability, ferroelectric liquid crystals have the excellent feature of high-speed response. This is because the spontaneous polarization of the ferroelectric liquid crystal and the applied electric field directly act to induce a transition in the orientation state, which is 3 to 4 orders of magnitude faster than the response speed due to the effect of the dielectric anisotropy and the electric field.

In this way, ferroelectric liquid crystals potentially have extremely excellent properties, and by utilizing these properties, many of the problems of the conventional TN type elements mentioned above can be overcome, which is quite essential. This results in significant improvements. In particular, it is expected to be applied to high-speed optical shutters and high-density, large-screen displays. For this reason, extensive research has been conducted on liquid crystal materials with ferroelectric properties, but the ferroelectric liquid crystal materials developed to date have sufficient characteristics for use in liquid crystal devices, including low-temperature operation characteristics and high-speed response. It is difficult to say that it is equipped with the following.

The following relationship exists between the response time τ, the magnitude of spontaneous polarization Ps, and the viscosity η as shown in the following equation [11] (where E is the applied electric field). Therefore, in order to increase the response speed, (a) increase the magnitude of spontaneous polarization Ps (b) viscosity η
There is a method of increasing the applied electric field E to reduce the . The applied electric field has an upper limit because it is driven by an IC or the like, and it is desirable that it be as low as possible.

Therefore, it is actually necessary to reduce the viscosity η or increase the value of the spontaneous polarization Ps.

In general, in ferroelectric chiral smectic liquid crystal compounds with large spontaneous polarization, the internal electric field of the cell caused by the spontaneous polarization is large, and there tends to be more restrictions on device configurations that can take a bistable state. Moreover, even if the spontaneous polarization is increased unnecessarily, the viscosity tends to increase accordingly, and as a result, it is conceivable that the response speed will not become very fast.

Furthermore, when the actual operating temperature range for a display is, for example, about 5 to 40 degrees Celsius, the response speed generally changes by about 20 times, which is currently beyond the limits of adjustment by drive voltage and frequency. .

As mentioned above, in order to put ferroelectric liquid crystal devices into practical use, a ferroelectric chiral smectic liquid crystal composition that has low viscosity, high-speed response, and small temperature dependence of response speed is required. .

[Problem that the invention seeks to solve]

An object of the present invention is to provide a liquid crystal composition, particularly a ferroelectric chiral smectic liquid crystal composition, which has a high response speed and reduced temperature dependence of the response speed, in order to make a ferroelectric liquid crystal element practical. , and to provide a liquid crystal element using the liquid crystal composition.

[Means to solve the problem]

The following general formula (I) (In the above formula (I), R8 is a linear alkyl group having 1 to 18 carbon atoms, and one methylene group in the alkyl group is replaced with 10-. R2 is a linear or branched alkyl group which may have a substituent having 1 to 18 carbon atoms, and one or more non-adjacent methylene groups in the alkyl group is-y---
y-c-1 CmiC- may be substituted.

Further, Y represents O or S. A is -A1- or -A
I-A2-, B is -B, - or -B, -B2-
shows. AI + A2 + Bl + B2 Indicates logen, cyano group, and methyl group. Also, X indicates a single bond when A is a single bond, and in other cases -OCH2-, -
Indicating CH20-, D is -69→.

Indicates a carbon atom. ); a liquid crystal composition containing at least one of the liquid crystal compounds;
The present invention also provides a liquid crystal element in which the liquid crystal composition is disposed between a pair of electrode substrates. In the liquid crystalline compound represented by general formula (I), R2 is preferably the following (i) -
(iii).

i) an n-alkyl group having 1 to 18 carbon atoms, more preferably 3 to 12 ii) CH3 (CH2) mCHCn H2n+ where m is an integer from 0 to 7; n is an integer from 2 to 9. Also, it may be optically active (iii) where r is an integer from O to 7, and S is O or 1. Further, t is an integer from 1 to 14. It may also be optically active.

Further, a preferable structural formula of the liquid crystal compound represented by the general formula (I) is the following ')+tt).

1) When -A- stands for -A, -, -A, - will appear.

A but A, -A2- When indicating, AI　A2- It will be revealed.

Furthermore, when the above i) represents a single bond, it more preferably represents -B1-, and is selected from the following. In ii) above, -B- is more preferably a single bond.

2 is preferably hydrogen or halogen, more preferably hydrogen or fluorine.

Conventionally, liquid crystals containing optically active halogenated alkyl groups and thiadiazole rings have been disclosed in Japanese Patent Application Laid-Open No. 62-5164.
No. 4 and JP-A No. 63-222148, both of which only deal with cases where the halogen is a base, and do not show any compounds for fluorine, nor do they suggest any effects of fluorine.

[Detailed description of the invention]

A general method for synthesizing the compound represented by the general formula (I) is shown below.

R, -CH * A-CCj! (R+ + R21 X.

A.

(B conforms to the general formula above) If X is other than a single bond, or is replaced with, etc. in R2, A is a removable protecting group.
Alternatively, it is also possible to protect the functional group present in B, close the ring to a thiadiazole ring, and then remove the protecting group.

Further, the optically active liquid crystal compound of the present invention is preferably an optically active 2-fluoroalkanoic acid shown in the specification of Japanese Patent Application No. 1982-077699 filed by the present applicant and others; 232886゜Special application 1986-
It is synthesized from the optically active 2-fluoroalkanol shown in the specification of No. 92378.

A specific structural formula of the optically active liquid crystal compound represented by general formula (I) is shown below.

(1 1) (1 2) (1 3) (1 4) (1 5) (1-6) (1-7) (i-s) (1-9) (1 10) (1 11) (1 -12) (1-13) (1-14) (1-15) (1 16) (1 17) (1 18) (1-19) (1 20) (1 21) (1 25) (1 26 ) (1 27) (1 28) (1-29) (1-30) (1 31) (1 32) (1-33) (1-34) (1 35) (1 36) (1 37) ( 1 38) (1 39) (1 40) (1 41) (1 42) (1 43) (1 44) (1-45) (1 46) (1 47) (1 48) (1 49) (1 -50) (1 51) (1 52) (1 53) (1 54) (1-55) (1-56) (1-57) (1 58) (1 59) (1-60) (1- 61) (1-62) (1 63) (1-64) (1-65) (1-67) (1-68) (1-69) (1-70) (1 71) (1 72) ( 1 73) (1 74) (1 75) (1-76) Su (1 77) (1-78) (1-79) (1 80) (1-81) (1-82) (1 83) ( 1 84) (1 85) (1-86) (1-87) (1-88) Su (1-89) (1 90) (1 91) (1 93) (1-94) (1 95) ( 1-96) (1-97) (1 98) (1 99) (l 100) (1 101) (1-102) (1-103) (1 104) (1 105) (1 106) (1 -107) (1 108) (1 109) (l 110) Moreover, the liquid crystal composition of the present invention contains at least one optically active liquid crystal compound represented by the general formula (I) as a compounding component. For example, when this optically active liquid crystal compound is combined with a ferroelectric liquid crystal represented by the following formulas (1) to (13), spontaneous polarization increases and response speed can be improved.

In such cases, the optically active liquid crystal compound of the present invention represented by general formula (1) may be added to the resulting liquid crystal composition.
．． It is preferably used in a proportion of 1 to 99% by weight, particularly 1 to 90% by weight.

(2) C6H130+co=N+CB=co-coocu2j
HCH34,4 Azoxycinnamic acid-bis(2methylbutyl) ester (MBRA 8) 28℃ crystal □ 55℃ 8mC*;==262℃ SmA;22 isotropic phase (11) ;=:= cholesteric Phase; = = 竺 Tomoyoshi phase Biphenyl 4' carboxylate (]3) Biphenyl 4' carboxylate crystal 83.4℃ Cholesteric phase 114℃ 11-← Isotropic phase In addition to the above compounds, the following liquid crystalline Compounds are also suitable for combination.

Furthermore, by blending the compounds shown below with smectic liquid crystals which are not chiral themselves, a composition usable as a ferroelectric liquid crystal can be obtained.

In this case, the optically active liquid crystal compound of the present invention represented by general formula (1) is added in an amount of 0.1 to 99% by weight of the resulting liquid crystal composition.
It is particularly preferable to use it in an amount of 1 to 90% by weight.

Such a liquid crystal composition can obtain large spontaneous polarization depending on the content of the optically active liquid crystal compound of the present invention.

0 C6HI34 QC6H.

0 Cl5HII -@-CH20f pa4coc 8HIT both C3H7 CH20-@9-C6Hl3C5HII C
H2O No.Kin C6H,3 C3H7sha CH2O No.Kin C1゜H21 C8H,□()CH20-@-KinCl2H25Also, the optically active liquid crystal compound represented by the general formula (I) can be added to nematic liquid crystal to form TN This is effective in preventing the occurrence of reverse domains in type cells. In this case, it is preferable to use the optically active liquid crystal compound of formula (I) in a proportion of 0.01 to 50% by weight of the resulting liquid crystal composition.

Furthermore, by adding it to a nematic liquid crystal or a chiral nematic liquid crystal, the chiral nematic liquid crystal can be used as a liquid crystal composition in a phase change type liquid crystal element or a white tiller type guest-host type liquid crystal element. In this case, 0.01 to 8 of the obtained liquid crystal composition
It is preferable to use the optically active liquid crystal compound of formula (I) in a proportion of 0% by weight.

The present invention will be explained in more detail below with reference to Examples.

Example 1 Production of 2-(1-fluoroheptyl)-5-(4-undecanoyloxyphenyl)-1,3,4-thiadiazole (Exemplary Compound 1-2) 2-(1-fluoroheptyl) hebutyl)-5-
(4-Undecanoyloxyphenyl)-1゜3.4-
Thiadiazole was produced.

Step 1) Step 2) υ Step 1) Production of 1-fluoroheptyl hydrazide 2-fluorooctanoic acid chloride 4 in 100 mjH of ethanol
．． 60g (25.5mmol) was added dropwise, and 1
heated for an hour. Then add 5.1 hydrazine hydrate to this solution.
g (100 mmo 1 ) was added thereto, and the mixture was heated under reflux for 4 hours.

After the reaction is complete, ice water 100mI! was added, cooled, and the precipitated crystals were filtered and washed with water and ethanol, respectively.3.
20 g (18.2 mmo+) of hydrazide were obtained.

Step 2) N-(1-fluoroheptyl) -N' -4
-Production of acetoxybenzodihydrazide 3.37 g (18.7 mmo) of 4-acetoxybenzoic acid
l) and 25 mI of thionyl chloride! After heating to reflux, excess thionyl chloride was distilled off to obtain 4-acetoxybenzoic acid chloride. Add 3゜0 g of hydrazide obtained in step 1 to this.
(17,0 m mol ), 4 mj of pyridine!
A mixed solution of 50 ml of dioxane and dioxane was added, and the mixture was heated under reflux for 2 hours. After the reaction is complete, add 200mj of saline! The precipitated crystals were filtered and washed with water and methanol, respectively, to obtain 5.54 g (16.4 mmol) of dihydrazide.

Step 3) Production of 2-(1-fluorohbutyl)-5-(4-hydroxyphenyl)-1,3,4-thiadiazole 5.07 g (15.0 mmol) of the dihydrazide obtained in Step 2 and Lawesso in 25 ml of tetrahydrofuran
Add 6.67 g (16.5 mmol) of n's reagent 7
Stirred at 0°C for 1 hour. After the reaction was completed, an aqueous sodium bicarbonate solution (5%) was added and extracted with ether. After distilling off the solvent, add 40ml of ethanol and sodium hydroxide (95%
)1.9 g (45 mmol) was added and stirred at room temperature for 1 hour. After the solvent was distilled off, 3N-H (1) was added to adjust the pH to 5-6, and the mixture was extracted again with ether. Anhydrous sodium sulfate was added to the extract and the solvent was distilled off, resulting in a column of crude crystals. Chromatography (toluene) and recrystallization (toluene/methanol) yielded 3.20 g of the target product.
I got it.

Step 4) Production of 2-(1-fluoroheptyl)-5-(4-undecanoyloxyphenyl)-1,3,4-thiadiazole Add pyridine to 2-(1-fluoroheptyl)-54-(4-hydroxy Phenyl) -1,3,4-thiadiazole 0.60 g (2,0 mmol) was added and undecanoic acid chloride 0.50 g (2,5 mmol) was added in a water bath.
o 1 ) was added dropwise, and the mixture was stirred at 60°C for 2 hours. After the reaction was completed, water was added, extracted with ether, dried, the solvent was distilled off, and purified by column chromatography (toluene:ethyl acetate-6=1) and recrystallization (ethanol) to obtain 0.70 g of the target product. Obtained.

Phase transition temperature (°C) Example 2 Production of 2-(l-fluoroheptyl)-5-(4-decyloxyphenyl)-1,3,4-thiadiazole (exemplified compound 1-12) by the method of Example 1 Obtained 2-(1-fluoroheptyl)-
2-(l fluoroheptyl)-5-(4-decyloxyphenyl)-1,3,4 thiadiazole was produced using 5-(4-hydroxyphenyl)-1,3,4 thiadiazole according to the following steps. .

2-(l-fluorohebutyl)-5-(4
-hydroxyphenyl) -1,3,4-thiadiazole 0.40g (1,36mmol), decyl iodide 0.44g (1,67mmol) and potassium hydroxide 0.
．． 12 g was added and stirred at 100°C for 6 hours. After the reaction was completed, water was added and the mixture was extracted with ether, dried, the solvent was distilled off, and purified by column chromatography (toluene) and recrystallization (ethanol) to obtain 0.45 g of the desired product.

Phase transition temperature ('C) 52.1 83.9 87.2
94.8Cry4-+S3◆-+So*◆-
+5A4-4Iso.

Example 3 Preparation of 2-decyl-5-[4-(2-fluorooctyloxy)phenyl]-1,3,4-thiadiazole (Exemplary Compound 1-50) Adding 2-decyl-5-(4-hydroxy) to butanol phenyl)-1,3,4thiazole 3.1g (9,9m
mol), 3.0 g (9.9 mmol) of 2-fluorooctyl p-toluenesulfonate, and 0.72 g of potassium hydroxide were added, and the mixture was stirred at 100°C for 6 hours. After the reaction was completed, water was added, extracted with ether, and the dry solvent was distilled off.
Purification was performed by column chromatography (toluene) and recrystallization (ethanol) to obtain 3.5 g of the desired product.

Phase transition temperature ('C) Example 4 Production of 2-(4-octylphenyl)-5-[4-(2fluorooctyloxy)phenyl]-1,3,4thiadiazole (exemplified compound 1-96) 2-
(4-octylphenyl)-5-(4-hydroxyphenyl)-1,3,4thiadiazole4. OOg (1
1.0 mmo+), 3.32 g (11.0 mmol) of 2-fluorooctyl P-)luenesulfonate, and 0.80 g of potassium hydroxide were added, and the mixture was stirred at 100° C. for 6 hours. 150 mj of water after the reaction is complete! was added, and the precipitated crystals were separated by filtration, column chromatography (toluene; ethyl acetate = 3:1), and recrystallization (toluene/ethanol).
Purification was performed to obtain 3.8 g of the target product.

Phase transition temperature ('C) Example 5 A liquid crystal composition A containing the liquid crystal compound produced in Example 1 as a compounding component was prepared. Further, as a comparative example, a liquid crystal composition B not containing the liquid crystal compound of Example 1 was also prepared. The phase transition temperature and spontaneous polarization of liquid crystal compositions A and B are shown.

<Liquid crystal composition A> Liquid crystal composition B> U phase transition temperature (℃) Liquid crystal composition A Ask 7 2 5 Iso.

A h Iso.

Liquid crystal composition B 20 53 ■so, 10-+S? ;-10SA 5 →---To Ch 6 →---To Iso.

Spontaneous polarization (n C/ crd ) Temperature Liquid crystal composition A Liquid crystal composition B25
24.5 2.535 17.7
1.940 14.8 1.
Twenty-two glass plates with a thickness of 0.7 mm were prepared, an ITO film was formed on each glass plate to form a voltage application electrode, and Si02 was further vapor-deposited thereon to form an insulating layer.

A 0.2% isopropyl alcohol solution of a silane coupling agent [KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.] was applied onto the glass plate at a rotation speed of 200 Or, p, m for 15 seconds to perform surface treatment. Thereafter, a heat drying treatment was performed at 120° C. for 20 minutes.

Polyimide resin precursor [Toshishiku Co., Ltd. 5P-510] 2 is placed on a glass plate with an ITO film that has been surface-treated.
% dimethylacetamide solution at a rotation speed of 200 Orr.

Application was performed using a 96m spinner for 15 seconds. After film formation, 60
A heating condensation firing process was performed at 300° C. for 1 minute. The thickness of the coating film at this time was approximately 700.

This fired coating was rubbed with acetate flocked cloth, then washed with isopropyl alcohol solution, and alumina beads with an average particle size of 2 μm were sprinkled on one glass plate, so that the rubbing axes of each plate were aligned with each other. The glass plates were glued together using an adhesive sealant [Rixon Pond (Chisso Corporation)] so that they were parallel to each other, and dried by heating at 100'C for 60 minutes to create a cell.The cell thickness of this cell was determined by Berek phase When measured by a board, it was approximately 2
It was μm.

Here, the ferroelectric liquid crystal compositions A and M previously prepared were each vacuum injected into the fabricated cell in a homogeneous mixed liquid state under a positive phase. A ferroelectric liquid crystal element was created by slow cooling at 0.5°/h from the isochron layer.

Using this ferroelectric liquid crystal element, the optical response (change in amount of transmitted light from 0 to 90%) under crossed Nicols is detected by applying a voltage of 30 V peak-to-peak, and the response speed (
(hereinafter referred to as optical response speed) was measured.

The results are shown below.

Response speed (μ5ec) Temperature Liquid crystal composition A Liquid crystal composition B25
394 128035 184
69040 140 550 Composition A containing the optically active liquid crystal compound of the present invention has larger spontaneous polarization and faster response speed than Composition B which does not contain it. From the above results, it is clear that the characteristics were greatly improved by combining the optically active liquid crystal compounds of the present invention.

Example 6 Similarly, a liquid crystal composition C containing the liquid crystal compound produced in Example 1 as a compounding component was prepared.

The phase transition temperature and spontaneous polarization of liquid crystal composition C are shown below.

Liquid crystal composition C> Phase transition temperature ('C) Spontaneous polarization (n c / crd) Temperature Liquid crystal composition C 1O4,6 303,5 452,1 Next, Example 5 was prepared using the same cell as in Example 5. The response speed was measured in the same manner. The results are shown below.

Response speed (μ5ec) Temperature Liquid crystal composition C 10595 30261 45165 From the above results, a liquid crystal composition with a fast optical response speed was obtained by using the compound of the present invention.

Example 7 ITO (Indium Tin 0
A bottom film was formed on the glass substrate on which the film was formed by spinner coating using a polyimide resin precursor [5P-510 manufactured by Toshishiku Co., Ltd.], and then baked at 300° C. for 60 minutes to obtain a polyimide film. Next, this film was subjected to an orientation treatment by rubbing, and cells were prepared so that the rubbing axes were perpendicular to each other (cell spacing: 8 μm). A nematic liquid crystal composition [Rixon GR-63: biphenyl liquid crystal mixture manufactured by Chisso Corporation] was injected into the above cell to form a TN (twisted nematic) type cell, and when observed with a polarizing microscope, a reverse domain (striped pattern) was observed. ) was found to be occurring.

When a TN cell was observed in the same manner as above using a liquid crystal mixture obtained by adding the liquid crystal compound of Example 1 of the present invention (1 part by weight) to the Rixon GR-63 (99 parts by weight), it was found that reverse No domains were observed, indicating a nematic phase with good uniformity. This indicates that the liquid crystalline compound of the present invention is effective in preventing reverse domains.

〔Effect of the invention〕

According to the present invention, a liquid crystal compound with good electric field responsiveness was obtained. Furthermore, it was confirmed that the liquid crystal composition and liquid crystal element containing the liquid crystal compound not only improve the response speed but also are effective in preventing reverse domains.

Claims (3)

[Claims] (1) The following general formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are included ▼ (I) (In the above formula (I), R_1 is a linear alkyl group having 1 to 18 carbon atoms, and One methylene group in the alkyl group may be replaced with -O-.R_
2 is a linear or branched alkyl group which may have a substituent having 1 to 18 carbon atoms, and one or more non-adjacent methylene groups in the alkyl group are -Y
−, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas , tables, etc. ▼, may be replaced by -C≡C-. Further, Y represents O or S. A is -A_1- or -
A_1-A_2-, B is -B_1- or -B_
1-B_2- is shown. A_1, A_2, B_1, B_2
▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas , There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, Indicates a single bond. Z represents hydrogen, halogen, cyano group, or methyl group. Also, X_1 indicates a single bond when A is a single bond, and in other cases indicates -CH_2O-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼. n is 0 or 1, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, -OCH_2-, -CH_2O-, D is ▲ mathematical formula,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼. * indicates an asymmetric carbon atom. ) optically active liquid crystal compound. (2) A ferroelectric chiral smectic liquid crystal composition containing at least one of the liquid crystal compounds according to claim 1. (3) A liquid crystal element, characterized in that the liquid crystal composition according to claim 2 is disposed between a pair of electrode substrates.