JPH0780816B2 - Optically active liquid crystal compound and composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a liquid crystal compound and a liquid crystal composition, and particularly to provide a liquid crystal material having ferroelectricity, which is superior to conventional liquid crystal materials. In particular, the present invention provides a liquid crystal material having excellent responsiveness and memory property and being applicable to a liquid crystal display device.

<Prior Art> A liquid crystal display device has many excellent features such as low voltage operability, low power consumption, a thin display, and a light receiving type that can be used in a bright place without causing eye strain. Therefore, it is widely used as various display elements at present. Currently, the display format is Tw
What is called isted Nematic (TN) type is the most common. This TN type display system uses a nematic liquid crystal, but it has all of the above excellent features, but its response is very slow compared to other light emitting type display systems such as CRT. There was a drawback. Also, when the applied electric field was turned off, the display memory (memory effect) was not obtained because the display returned to the original state. For these reasons, it cannot be said that it is suitable for high-speed response and response to moving screens such as optical shutters, printer heads, and televisions, which require time-division operation, due to various restrictions.

In addition to the TN type as a liquid crystal display element, a guest-host (G
H) type, birefringence control (ECB) type, phase transition (PC) type, thermal effect type, etc. have been researched and developed, and each has its own characteristics, but in terms of its responsiveness, both are TN type. Compared to this, no particular improvement was made. For these,
A so-called dual frequency drive type has been developed as a liquid crystal display system that can provide a high-speed response, and its response has been considerably improved, but it is still not sufficiently satisfactory and its operation It had a defect that the circuit became too complicated. For this reason, attempts have been made to develop a new liquid crystal display system that is more responsive.

Ferroelectric liquid crystals have recently been announced to meet this purpose. (R. Mayer et al: J. Physique 36 L69 (197
5)) It is pointed out that the display device using this ferroelectric liquid crystal has a high speed response of 100 to 1000 times compared with the conventional liquid crystal display and a memory effect brought about by bistability (NAClark, STLagerwall : Appl Phys. Lett; 3
6 899 (1980)), can be expected to be applied to display devices on the other side such as moving screens of televisions, high-speed optical shutter printer heads, computer terminals, etc.

Ferroelectric liquid crystals belong to the tilt-type chiral smectic phase as the liquid crystal phase, but among them, the practically desirable one is the chiral smectic C (hereinafter abbreviated as SC ^* ) phase having the lowest viscosity. It is called.

Liquid crystal compounds exhibiting the SC ^* phase have been studied so far, and many compounds have already been synthesized. However, these SC ^* compounds alone show the ferroelectricity in a wide temperature range including room temperature including the following conditions for use as a ferroelectric liquid crystal display device, and (b) exhibit a long helical pitch. (C) having an appropriate tilt angle, (d) a large value of spontaneous polarization, (e) a low viscosity, (f) a high-speed reaction as a result of (d) and (e) above. It is not known that the compound exhibits the property, and it is necessary to mix a plurality of compounds and use it as an SC ^* liquid crystal composition.

There are two methods to obtain SC ^* liquid crystal composition, one is
This is a method of mixing a plurality of compounds exhibiting an SC ^* phase, and the other method is a method of adding a chiral liquid crystal compound to a liquid crystal compound or a composition exhibiting a non-chiral SC phase.

With the former method, it is easy to obtain a wide temperature range and strong spontaneous polarization. However, the compound having the SC ^* phase has an asymmetric carbon in the molecule, particularly in the side chain, and has a branching group (mainly a methyl group). The closer the branching group is to the liquid crystal central skeleton (core) portion and the permanent dipole such as the carbonyl group, the greater the spontaneous polarization of the liquid crystal, but at the same time, the viscosity of the liquid crystal tends to be increased. Therefore, even if the spontaneous polarization of the liquid crystal is increased, the viscosity is large especially in the low temperature range, and it is not easy to obtain a high-speed response of 200 μsec or less near room temperature.

In the latter method, although it depends on the amount of the chiral liquid crystal compound to be added, it is difficult to obtain a composition having a very large spontaneous polarization as the matrix SC liquid crystal does not have spontaneous polarization. However, since the liquid crystal compound in the matrix SC liquid crystal composition does not require the presence of a branching group,
It has a very low viscosity. Therefore, it is easy to obtain a high-speed response by adding a chiral liquid crystal compound and giving spontaneous polarization as SC ^* liquid crystal. At present, the latter method is becoming mainstream.

The chiral liquid crystalline compound added to the SC liquid crystal composition does not necessarily need to exhibit the SC ^* phase by itself and does not necessarily need to exhibit the liquid crystal phase, but it does not narrow the temperature range of the composition. Is preferably a liquid crystal phase, particularly an SC ^* phase. Further, in order to increase the spontaneous polarization of the composition as much as possible, a molecular structure capable of exhibiting a large spontaneous polarization, that is, the asymmetric carbon of the chiral group is as close as possible to the liquid crystal central skeleton (core), and the It should be as close as possible to a permanent dipole. However, since the compound having such a structure also has a stronger twisting force on the liquid crystal phase, a liquid crystal phase in which a helix appears (SC ^* phase, etc.)
In this case, the pitch became too short, the orientation was adversely affected, and it was difficult to increase the cell thickness. Therefore, it is necessary to control the pitch of the SC ^* liquid crystal composition by limiting the addition amount thereof or by adding a chiral compound having the opposite twist direction. In this case, if the direction of the spontaneous polarization of the chiral compound opposite to the twist direction is also the opposite direction, the spontaneous polarization of the composition is canceled and becomes smaller.
There were many troubles in adjusting the pitch. for that reason,
A chiral liquid crystal compound having a large pitch and having an SC ^* phase even if it has a large pitch and has a large spontaneous polarization has been desired.

<Problems to be Solved by the Invention> An object of the present invention is to have a sufficiently large pitch while having a large spontaneous polarization, and in many cases, to have an SC ^* phase by itself, which may be used alone or as a mixture. To provide a novel chiral liquid crystal compound exhibiting an SC ^* phase in a wide temperature range including room temperature and capable of high-speed response, and a liquid crystal compound or a liquid crystal composition showing the SC phase and the SC phase. To prepare an SC ^* liquid crystal composition capable of high-speed response from the same, and to provide such a composition,
Furthermore, it is to provide an optical display device having a fast response by using these SC ^* liquid crystal compounds and compositions.

<Means for Solving the Problem> The chiral liquid crystal compound in the present invention is characterized by being an ester compound having two asymmetric carbon atoms in the molecule as represented by the following general formula (I). .

In the above formula, R represents an alkyl group having 2 to 16 carbon atoms, more preferably an alkyl group having 2 to 6 carbon atoms, m and n each represent an integer of 1 or 2, and x
Represents an integer of 0 to 5, more preferably an integer of 0 or 1, * means that the carbon is an asymmetric carbon having (R) or (S) configuration, and ** means that the carbon is (S) configuration. It represents that it is an asymmetric carbon.

The liquid crystal composition in the invention contains at least one compound represented by the general formula (I) (hereinafter abbreviated as compound (I)), and preferably exhibits a chiral smectic phase. It is a liquid crystal composition. More preferably, it is a chiral smectic liquid crystal composition obtained by mixing at least one compound (I) with a liquid crystal compound or composition exhibiting a smectic C phase, and particularly, as a compound or composition exhibiting a smectic C phase, It is preferable that the main component is a compound showing an SC phase without a branching group in the side chain.

Compound (I) has the general formula (In the formula, R, m and * are the same as the above.) The optically active carboxylic acid represented by the formula is converted to an acid chloride with a chlorinating agent such as thionyl chloride, (In the formula, n, x, and ** are the same as the above), and can be easily obtained by reacting an optically active phenol derivative represented by the formula (1) in the presence of a basic substance such as pyridine.

Carboxylic acid (II) is 4-hydroxybenzoic acid (m = 1
Or 4'-hydroxybiphenyl-4-carboxylic acid (when m = 2) or their lower alkyl ester and an optically active alcohol. O-tosylate Can be obtained by reacting and under a basic condition, and when an ester is used, it is hydrolyzed and then treated with an acid.

The optically active phenol derivative (III) can be synthesized as follows.

That is, it can be obtained by reacting hydroquinone (when n = 1) or biphenol (when n = 2) with an acid chloride represented by the general formula (IV) in the presence of a basic substance such as pyridine. .

Here, the acid chloride (IV) can be easily derived from (S) -2-methylbutanol by a known method. For example, when x = 0, (S) -2-methylbutanol is directly oxidized and then treated with thionyl chloride or the like, and when x = 1, (S) -2-methylbutanol is brominated. As (S) -2-methylbutyl bromide,
It can be obtained by converting a Grignard compound with magnesium, reacting it with carbon dioxide to obtain (S) -3-methylvaleric acid, and then treating with thionyl chloride.

The most structural feature of compound (I) is that it has two asymmetric carbons in the molecule. One chiral group Is derived from natural (S) -2-methylbutylacol, its configuration is always (S), and the other chiral group is an optically active alcohol. And has a steric configuration of (S) or (R).

As shown in the synthetic method, optically active alcohol Is converted to O-tosylate and then reacted with hydroxycarboxylic acid or its ester to introduce a chiral group, but it is considered that the configuration is retained in the first step (tosylation). The second step is the reaction at the optically active center, but it is generally said that the reaction between the alcoholate and the tosylate under basic conditions has a reversed configuration. However, since the configuration after the reaction could not be determined directly, the optically active alcohol used as a raw material will be described below. By showing the configuration of The absolute configuration of the groups will be shown. That is, for example, (S)-
This is represented by the case where it is derived from 2-octanol ((S)), and the case where it is derived from (R) -2-octanol ((R)), and it is represented by (S) in the case of a chiral group derived from a 2-methylbutyl group. ) -Is used separately. In reality, it is highly possible that ((S)) represents (R) and ((R)) represents (S).

The most important characteristic of the compound (I) in terms of physical properties is that it has a very large spontaneous polarization, but its pitch is quite large. It is already known that among a liquid crystal compound in which an asymmetric carbon is directly bonded to a benzene ring by an ether bond, one having a large spontaneous polarization, for example, A value of 89 nC / cm ² has been reported for the compound shown in (JP-A-61-43).

However, since these compounds have a strong twisting force by themselves, their pitch in the SC ^* phase is very small, and when they are used as a composition, a considerable amount of the opposite twisting direction is added. Then, it was necessary to greatly adjust the pitch. On the other hand, derived from (S) -2-methylbutanol SC ^* liquid crystal compounds having a group are also known (Japanese Patent Application No. 61-
18014, ibid. 61-78178, etc.), the spontaneous polarization of these types is about 10 to 15 nC / cm ² even for the largest x = 0 type and less than that for x ≧ 1.

The present inventors have found that such a chira group It is noted that the twisting force exerted by the liquid crystal compound on the liquid crystal compound is not so different from the spontaneous polarization of the compound in which the asymmetric carbon is directly linked to the benzene ring by an ether bond, and the optical activity of both of them in the same molecule. The present invention is based on the idea that a liquid crystal compound having a group may have a large spontaneous polarization, but the twisting force may be canceled and the resulting liquid crystal compound may have a large pitch.

In fact, the compound (I) has a large spontaneous polarization of about 100 nC / cm ^2, but in the SC ^* liquid crystal composition obtained by adding about 30% to the SC liquid crystal containing no chiral group, the helical pitch is A thickness of 10 μm or more can be obtained which requires almost no adjustment.

It is known that the twisting direction of the helix by the group is left-handed when x is an even number such as 0, 2, 4, etc., and right-handed when x is an odd number such as 1, 3, 5, etc.

Also, The twisting direction of the helix by the group is left-handed in the case of the ((S)) form derived from the secondary optically active alcohol of the (S) form,
It is known that the ((R)) body is right-handed.

Therefore, in the present compound (I), the ((S)) isomer when x is an odd number and the ((R)) isomer when x is an even number are a preferable combination in which the helical twisting forces are mutually canceled.

The direction of spontaneous polarization derived from both optically active groups is not always equal to the direction of helical twist, and even when the helical twist cancels out and becomes large, the spontaneous polarization is inversely added. It may be large or may be small. while doing The spontaneous polarization derived from the group It is extremely small as compared with the spontaneous polarization derived from the group, for example, when x = 0, it is about one order of magnitude smaller or less, and therefore compound (I) can always have a large spontaneous polarization.

Regarding the direction of spontaneous polarization derived from a group, it is a well-known ferroelectric liquid crystal (S) -2-methylbutyl p-.
Decyloxybenzylidene aminocinnamate (DOBAMB
It is known that when the direction of C) is, for example, when x = 0. on the other hand, The direction of spontaneous polarization derived from the group is ((R)) type,
In the ((S)) type. Therefore, in the case of x = 0, the ((R)) type When combined with a group, it is possible to obtain a very preferable compound in which spontaneous polarization is added and increased, and the twisting forces cancel each other out to increase the pitch. This is something that has not been predicted so far.

In general, when a branching group is introduced into a liquid crystal molecule in its side chain, its crystallinity is lowered and its phase transition temperature tends to be lowered. Since the compound (I) has branched methyl groups on both side chains, its phase transition temperature is low. For example, even in the 3-ring type, the clearing point is only around 80 ° to 100 ° and exhibits ferroelectricity. S
The C ^* phase also appears only monotropically or does not show at all. However, it is more effective to use the compound (I) as an SC ^* liquid crystal by mixing it with an SC liquid crystal compound or composition having no branched chain, and it is not a problem in practice.

When a SC ^* liquid crystal composition is prepared from a chiral compound and an SC liquid crystal compound or an SC liquid crystal composition, it becomes a chiral compound.
SC ^* If the liquid crystal is no SC in its composition ^*
Although the temperature range of the phase tends to be narrowed, many compound (I) shows the SC ^* phase, and SC ( ^* ) alone shows the SC ^* phase ^.
Even if it does not show a phase, it often has an SC ^* property that can show an SC ^* phase in a supercooled state obtained by mixing or the like, so its temperature range is not narrowed so much.

Now, the compound (I) is used alone or in combination with a plurality of compounds.
As the SC liquid crystal compound or composition, for example, in the case of a bicyclic type, a phenylbenzoate compound (A) as shown below
And the pyrimidine-based compound (B) or a mixture thereof. Further, in order to extend the temperature range of the SC phase to a high temperature range, tricyclic compounds (C) and (D) can be used.

A: (R ₁ and R ₂ represent a linear alkyl group, an alkoxy group, an alkylcarbonyloxy group, an alkoxycarbonyl group or an alkoxycarbonyloxy group, and may be the same or different.) B: (R ₃ and R ₄ represent a linear alkyl group or an alkoxy group, and may be the same or different.) C: (R ₃ and R ₄ are the same as above, and m + n = 3.) D: (R ₃ and R ₄ are the same as above, and Y ₁ and Y ₂ are each -COO- or Represents Although these can be used alone, it is convenient to use them as a composition of two or more components because a wider temperature range can be obtained. Further, other than (A) to (D), those having a straight chain alkyl group and exhibiting an SC phase can be similarly used. In addition, compounds other than (A) to (D), which are liquid crystal compounds having a low viscosity even if they do not exhibit an SC phase by themselves, can be added in a small amount to reduce the viscosity of the composition, resulting in a high response speed. Is an effective way to obtain.

Now, in the SC ^* liquid crystal composition obtained by adding about 10 to 30% of the compound (I) to the SC liquid crystal composition, the helical pitch is about 5 to 15 μm when the twist directions are offset. To be

When it is used as a display element, it needs to be oriented and unwound, but in the case of a thick cell of 5 to 6 μm or thicker, a larger pitch may be required to achieve this state. is there. As the compound for adjusting the pitch, the compound (I) has the opposite twist direction and the same spontaneous polarization direction, or even if the spontaneous polarization direction is opposite, several nC / cm ² The following small materials can be used. In the compound (I), a small amount of the pitch adjusting compound is sufficient when the twists of the helix are offset, and a considerable amount is required when the twist of the helix is added.

Now, the obtained liquid crystal compound or composition has a uniform thickness (about 1 μm to 20 μm) between two transparent electrode plates.
The thin film of can be used as a liquid crystal display cell.

In the display cell, the liquid crystal molecules need to be monodomains in which the major axis of the liquid crystal is parallel to the electrode surface, that is, a so-called homogeneous and uniform orientation. For this purpose, the surface of the electrode plate is subjected to an orientation treatment by rubbing, vapor deposition, etc., an electric field or a magnetic field is applied, a temperature gradient is given, or a combination of a plurality of these means is used. The direction in which the liquid crystal phase is gradually cooled to the liquid crystal phase for alignment is generally adopted. Even with the compound or composition of the present invention, a uniformly oriented monodomain cell can be obtained by such a method.

<Effects of the Invention> The outline of the present invention is as described above. However, when the compound (I) in the present invention is used alone or in a mixture to form an SC ^* liquid crystal composition, a conventionally known ester-based ferroelectric property is used. It has a large spontaneous polarization as compared with a liquid crystal compound, and when a helical pitch is added to an SC liquid crystal compound or composition and used as an SC ^* liquid crystal composition, does pitch adjustment be necessary? Or very easy.

In addition, the compound (I) can be easily produced industrially, is colorless in itself, and has excellent chemical stability against light, moisture, heat, etc., as shown in Examples described later. , Very practical.

Further, the ferroelectric liquid crystal compound and composition in the present invention have extremely high response speed, which is 100 times or more that of the conventional nematic liquid crystal, and are extremely promising as an optical switching element for display.

<Examples> Hereinafter, the present invention will be described in detail with reference to the present invention, but of course, the gist and the scope of application of the present invention are not limited to these examples.

The liquid crystal phase and the phase transition temperature were measured by using a polarization microscope equipped with a temperature adjustment stage and a differential scanning calorimeter (DSC), but the transition temperature slightly fluctuates depending on the purity of the sample or the measurement conditions. To do. The temperature means ° C.

In addition, the chemical structure of the product is the nuclear magnetic resonance spectrum (NM
R), infrared absorption spectrum (IR) and mass spectrum (M
S) confirmed.

In the NMR data, s is a singlet (singlet), d is a doublet (doublet), t is a triplet (triplet), dd is a doublet (double doublet), and m is a multiplet (multiplet). , P ⁺ in MS represents the parent peak.

Example 1 4-{(S) -2-Methylbutanoyloxy} phenyl 4 '-(1-methylheptyloxy) biphenyl-4-
Synthesis of carboxylate (((R)) form) (R) -2-
Pyridine 1 dehydrated from 130.0 g (1 mol) of octanol
And was cooled to 5 ° C. While gently stirring,
190.5 g (1 mol) of p-toluenesulfonyl chloride was added over 1 hour, taking care not to let the internal temperature exceed 10 ° C. After standing at 0 to 5 ° C for 8 hours, hexane 2 was added, the precipitated crystals were separated, and washed with 1% hydrochloric acid, water, and saturated saline. After dehydration over anhydrous sodium sulfate, the solvent was distilled off to obtain 239.7 g of (R) -1-methylheptyl p-toluenesulfonate (yield 84.4%). Then 4 '
-Hydroxybiphenyl-4-carboxylic acid 21.4 g (0.1 mol) and potassium hydroxide 11.2 g (0.2 mol) in ethanol
It was suspended in 350 ml of water and 40 ml of water and heated to a reflux temperature, and 31.2 g (0.11 mol) of (R) -1-methylheptyl p-toluenesulfonate was dissolved in 50 ml of ethanol and added dropwise over 30 minutes. The inside of the reaction system gradually became uniform. After completion of dropping, the mixture was refluxed for 1 hour and then allowed to cool, and 10% hydrochloric acid was added to make the mixture weakly acidic. Separate the precipitated crystals and add 200 m of benzene to this.
l was added to remove insoluble matter. The crude crystals obtained by distilling off benzene were recrystallized from a mixed solvent of hexane-ethyl acetate to give 4 '-{1-methylheptyloxy} biphenyl-
15.5 g of 4-carboxylic acid was obtained (yield 47.5%). This absolute configuration is considered to be the (S) -form, but since it has not been confirmed, it is expressed as the ((R))-form using the absolute configuration of the raw material used. This ((R)) form of 4 '-{1-methylheptyloxy} biphenyl-4-carboxylic acid 13.04 g (40
(Mmmol) was heated and stirred with 30 ml of thionyl chloride and 1.0 ml of pyridine for 2 hours, excess thionyl chloride was distilled off, 100 ml of dehydrated toluene was added to remove insoluble matter, and then toluene was distilled off to obtain ((R)). 12.12 g of 4 '-{1-methylheptyloxy} biphenyl-4-carboxylic acid chloride was obtained (yield 88%).

This acid chloride (1.99%, 5.8 mmol) was added to methylene chloride (25 m).
1.23 g (5.8 mmol) of 4-hydroxyphenyl (S) -2-methylbutanate synthesized from hydroquinone and (S) -2-methylbutyric acid chloride was dissolved in 5 ml of pyridine and added. The reaction was continued for 3 hours under reflux of the solvent. Ether (100 ml) was added, and the mixture was washed successively with 10% aqueous hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution, water and saturated brine, and dried over anhydrous sodium sulfate.

After the solvent was distilled off, the residue was purified by silica gel column chromatography (developing solvent: chloroform-hexane mixed system), and recrystallized from ethanol to give ((R))-form 4
-{(S) -2-Methylbutanoyloxy} phenyl 4 '-(1-methylheptyloxy) biphenyl-4-
1.66 g of carboxylate was obtained (yield 58%).

Spectral data for this compound are summarized in Table 2.

Phase transition temperature of this compound SC ^* -N ^* : 72 ° (SC ^* phase is monotropic) N ^* -I: 86 ° Melting point 81 ° Moreover, when this compound was made into a uniformly oriented thin film cell, its spontaneous polarization was measured. It showed a large value of 100 nC / cm ² at 52 ℃. The helical pitch alone is 1.2 at 67 ° C.
μm, and the direction is right-handed.

Example 2 Synthesis of 4 ′-{(S) -2-methylbutanoyloxy} biphenyl-4-yl 4- (1-methylheptyloxy) benzoate (((R)) form) In Example 1, 4 ′ -Hydroxybiphenyl-4-
4-Hydroxybenzoic acid was used in place of carboxylic acid, and 4-hydroxyphenyl (S) -2-methylbutanate was used in place of 4,4'-biphenol and (S) -methylbutyric acid chloride. ′ -Hydroxybiphenyl-4-
The same operation was performed using yl (S) -2-methylbutanate to obtain the title compound. The spectrum data is shown in Table 2 and the phase transition temperature is shown in Table 1. (Same as below) In the same manner as in Examples 3 to 6, 4 '-{(S) -2-methylbutanoyloxy} biphenyl-4-yl 4- (1-methylheptyloxy) benzoate (((S)) form). (Example 3) 4-{(S) -3-methylpentanoyloxy} phenyl 4 '-(1-methylheptyloxy) biphenyl-4
-Carboxylate (((S)) form) (Example 4) 4-{(S) -3-methylpentanoyloxy} phenyl 4 '-(1-methylheptyloxy) biphenyl-4
-Carboxylate (((R)) form) (Example 5) 4 '-{(S) -3-methylpentanoyloxy} biphenyl-4-yl 4- (1-methylheptyloxy) benzoate (((S )) Form) (Example 6).

The phase transition temperature is shown in Table 1 and the spectrum data is shown in Table 2.

Example 7 Preparation of optical switching element using SC ^* liquid crystal composition containing compound (I) 2- (4-ynyloxy) phenyl-5-octylpyrimidine 40w%, 2- (4-nonyloxy) phenyl-5
-SC liquid crystal composition was prepared from 40w% of heptylpyrimidine and 20w% of 4-octyloxyphenyl 4-decyloxybenzoate, and its phase transition point was as follows (w% represents weight percent). .).

70% by weight of this composition and 4-((S) -2-methylbutanoyloxy} phenyl 4 '-(1-methylheptyloxy) biphenyl-4- of the ((R)) form obtained in Example 1
An SC ^* liquid crystal composition was prepared from 30% by weight of carboxylate.

This composition is heated to the isotropic liquid phase and then cooled.
The N ^* phase at 68 °, the SA phase at 55 °, the SC ^* phase at 53 °, and the SC ^* phase were maintained up to 0 ° C. Also, when left at another temperature for a long time, it crystallized and its mp was 25.5 °.

The composition is heated to an isotropic liquid phase, which has a thickness of 2.
A thin film cell was prepared by filling the space between two glass transparent electrodes (one of which was subjected to a polyimide-rubbing orientation treatment) bonded via a 0 μm spacer. This was gradually cooled at a rate of 5 ° per minute to orient the N ^* phase and the SA phase to obtain a uniform SC ^* phase monodomain at 53 ° or less.

A square wave of ± 10 V, 50 Hz was applied to this cell and the intensity of the transmitted light was measured. For example, it was 54 μsec at 41 ° and 10 at 27 °.
A fast response of 7 μs was confirmed. As a result, a high-speed responsive optical switching display element was obtained.

The spontaneous polarization of this composition is 9.3 nC / cm ² (41 °), 11.5 nC / cm
² (27 °), and its tilt angle is 23.3 ° (41 °), 26.3
It was ゜ (27 ゜).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ogawa 246-4 Ikari, Kawaguchi City, Saitama Prefecture

Claims (8)

[Claims] 1. A general formula (I) (In the formula, R represents an alkyl group having 2 to 16 carbon atoms,
m and n each independently represent an integer of 1 or 2, and x represents an integer of 0 to 5. * Represents an asymmetric carbon having (R) or (S) configuration, and **
Represents an asymmetric carbon of (S) configuration. ) The crystalline compound shown by. 2. In the general formula (I), R has 2 to 6 carbon atoms.
The compound according to claim 1, wherein x is an integer of 0 or 1. 3. In the general formula (I), The twist direction of the liquid crystal helix derived from the base, The liquid crystal compound according to claim 1 or 2, wherein the twist direction of the helix of the liquid crystal derived from the group conflicts. 4. The general formula (I) (In the formula, R represents an alkyl group having 2 to 16 carbon atoms,
m and n each independently represent an integer of 1 or 2, and x represents an integer of 0 to 5. * Represents an asymmetric carbon having (R) or (S) configuration, and **
Represents an asymmetric carbon of (S) configuration. A liquid crystal composition containing at least one compound represented by the formula (1). 5. In the general formula (I), R has 2 to 6 carbon atoms.
5. The liquid crystal composition according to claim 4, which comprises a compound in which x is an integer of 0 or 1. 6. The liquid crystal composition according to claim 4, which exhibits a chiral smectic phase. 7. The liquid crystal composition according to claim 6, comprising a liquid crystal compound or composition exhibiting a smectic C phase, wherein the composition exhibits a chiral smectic C phase. 8. A compound represented by the general formula (I): The twist direction of the liquid crystal helix derived from the base, The liquid crystal composition according to claim 6 or 7, wherein the twist directions of the helix of the liquid crystal derived from the bases are opposite to each other.