JP2558488B2 - Liquid crystalline compounds that induce extremely large spontaneous polarization - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal compound useful as an electro-optical display material, and particularly to a liquid crystal material having ferroelectricity. It is intended to provide a liquid crystal material having excellent responsiveness and memory property and being applicable to a liquid crystal display device as compared with a liquid crystal material.

[Conventional technology]

The liquid crystal display element has low voltage operation, low power consumption,
It has many excellent features such as thin display, light receiving type, so it can be used even in bright places and eyes are not tired.
Widely used.

However, the most common TN type display method has extremely poor responsiveness as compared with other light emitting type display methods, and no display memory (memory effect) was obtained when the applied electric field was cut off. . For this reason, it cannot be said to be a system suitable for application to optical shutters, printer heads that require high-speed response, or moving screens such as televisions that require time-division driving, because of various restrictions.

As a display method that overcomes these drawbacks, a display method using a ferroelectric liquid crystal was recently announced by Meyer et al. This display system is expected to be a next-generation display device because it can achieve 100-1000 times faster response than the TN type and a memory effect due to bistability, and has been actively researched and developed in various fields.

Ferroelectric liquid crystals belong to a tilt-type chiral smectic phase as a liquid crystal phase, and among them, the practically desirable one is a chiral smectic C (hereinafter referred to 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 have the following conditions for use as a ferroelectric liquid crystal display element, namely (a) exhibit ferroelectricity in a wide temperature range including room temperature, and (b) a long helical pitch. (C) a proper tilt angle, (d) a large value of spontaneous polarization, (e) a low viscosity, (f) a high speed as a result of (d) and (e) above. It has not been known that it exhibits responsiveness, and it must be used as an SC ^* liquid crystal composition.

There are two methods for obtaining an SC ^* liquid crystal composition, one is a method of mixing a plurality of compounds exhibiting an SC ^* phase, and the other method is a chiral smectic C (hereinafter referred to as SC). In this method, a chiral liquid crystal mixture or composition is added to a liquid crystal compound or composition exhibiting a phase.

In the former method, SC can be used with strong spontaneous polarization and a wide temperature range ^.
A liquid crystal composition having a phase (hereinafter referred to as SC ^* liquid crystal composition) can be easily obtained. However, in such a composition, its viscosity becomes extremely large, and as a result, it is not easy to obtain a fast response.

In the latter method, although depending on the chiral compound to be added and the amount thereof, the SC compound as the host does not have spontaneous polarization, and therefore, it is difficult to obtain a large spontaneous polarization as the SC ^* liquid crystal composition. However, the SC liquid crystal composition that is the base (hereinafter referred to as the SC base liquid crystal composition) can have a very low viscosity, and it is possible to obtain an SC ^* liquid crystal composition with excellent high-speed response. And this method is now the mainstream.

Chiral liquid crystalline compound to be added to the SC mother liquid crystal composition is not necessarily indicating an SC ^* phase by itself, it is not necessary even to exhibit a liquid crystal phase, the SC ^* liquid crystal compositions SC ^*
In order not to narrow the temperature range of the phase, it is desirable to show a liquid crystal phase, particularly a tilt type chiral smectic phase.

In order to reduce the viscosity of the SC ^* liquid crystal composition, it is desirable to use as little chiral compound as possible, the viscosity of which is much higher than that of the SC host liquid crystal composition. However, if it is too small, the spontaneous polarization of the SC ^* liquid crystal composition becomes too small and the response becomes poor. In order to obtain a sufficient spontaneous polarization with the use of a small amount as much as possible, it is desirable that the spontaneous polarization (or induced spontaneous polarization) of the chiral compound alone is as large as possible. Alone
Some liquid crystal compounds exhibiting spontaneous polarization as large as 100 nC / m ² or more are known. However, in the currently known ones, the helical pitch of the composition is large in the chiral nematic (hereinafter abbreviated as N ^* ) phase and SC ^* phase in which the twisting force to the liquid crystal phase is strong and the helix appears due to the structure. It's too short. It is difficult to increase the cell thickness because it adversely affects the orientation. Therefore, it is necessary to limit the amount of addition or to add a chiral compound having a reverse twist direction to adjust the helical pitch, and at that time, the direction of spontaneous polarization of each chiral compound must not be the same. Then, the spontaneous polarization is canceled out, and as a result, the spontaneous polarization of the obtained liquid crystal composition becomes small, which is a troublesome point.

[Problems to be Solved by the Invention]

For the above reasons, a liquid crystal compound having a spontaneous polarization as large as possible, or capable of inducing a large spontaneous polarization, having a large helical pitch to induce it, and capable of exhibiting a chiral smectic phase by itself is desired. Was there.

The problem to be solved by the present invention is that the spontaneous polarization induced by addition and mixing in the SC host liquid crystal composition is extremely large, the helical pitch is relatively large, and the SC ^* phase is exhibited in a wide temperature range, resulting in high-speed response. Another object of the present invention is to provide a novel chiral liquid crystalline compound that enables the above.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a general formula A compound represented by In the above formula, R ₁ represents an alkyl group having 1 to 18 carbon atoms, and an alkyl group having 2 to 8 carbon atoms is preferable in order to obtain a compound having large spontaneous polarization and low viscosity.

Each independently represents a 1,4-phenylene group, or a 1,4-phenylene group in which one or two hydrogen atoms are replaced by a fluorine atom, a chlorine atom, a methyl group or a cyano group. Represents, Represents, It is more preferable that the case is represented. Y is an intermediate linking group, Alternatively, it represents a single bond. m and n each independently represent 0 or 1, but when m = n = 0, formula (I)
Is bicyclic, its liquid crystallinity is poor, and m =
In the case of n = 1, since it becomes a four-ring type and the viscosity increases,
More preferably, it is the case of a three-ring type of m + n = 1. R
₂ represents an alkyl group having 2 to 18 carbon atoms, and an n-hexyl group is more preferable in view of availability of the secondary optically active alcohol as a raw material. C ^* and C
^** represents independently that the carbon atom is an asymmetric carbon having (R) or (S) configuration, but as will be argued, more preferable is simultaneous (S) or simultaneous (R). ) Is the case.

The compound of formula (1) according to the present invention can be produced, for example, as follows. (I) Y is If it is [In the above formulas (II) to (VI), R ₁ , R ₂ , m, n, Have the same meanings as in formula (I). That is, the acid chloride, which is a lactic acid derivative represented by formula (II), is converted into a hydroxycarboxylic acid derivative of formula (III) in the presence of a base such as pyridine. The reaction yields a carboxylic acid of formula (IV). Next, this is converted to an acid chloride (V) with thionyl chloride or the like, and an optically active 2-alkanol ester of hydroxycarboxylic acid represented by the formula (VI) is reacted in the same manner to obtain Y The compound of the general formula (Ia) can be prepared. It can also be produced by directly esterifying the compound of the formula (IV) and the compound of the formula (VI) in the presence of a dehydrating condensing agent such as dicyclohexylcarbodiimide.

Here, the lactic acid derivative (II) was prepared by the present inventors in Japanese Patent Application No.
As shown in -140157, it can be produced by using ethyl lactate as a raw material, alkylating with silver oxide and alkyl iodide, hydrolyzing and treating with thionyl chloride.

The optically active 2-alkanol ester (VI) of hydroxycarboxylic acid is obtained by converting the OH group of hydroxycarboxylic acid (III) into a benzyl ether, or by acetylation,
After protection, the carboxylic acid is used as an acid chloride to give an optically active compound.
Esterify by reacting with alkanol. Finally, by removing the protecting group, the compound of formula (VI) can be produced.

Many hydroxycarboxylic acids (III) are known, and those with m (or n) of 0 are commercial products.
The substitution product which is not commercially available can be produced from a substituted phenol or a substituted phenylphenol by a conventional method. That is, it can be produced by methylating the OH group, acetylating the acetyl group to carboxylic acid by oxidation, and finally performing a demethylation reaction.

(Ii) Y is If it is The phenol derivative (VIII) can be produced by reacting the lactic acid derivative of the formula (II) with the hydroquinone represented by the formula (VII) or 4,4′-biphenol or a substitution product thereof. On the other hand, a dicarboxylic acid monoester (IX) is converted to an acid chloride (X), which is reacted with a phenol derivative (VIII) to give a compound of the general formula (I
-The compound of b) can be produced. Also, the formula (VI
The compound of II) and the compound of formula (IX) may be directly condensed and esterified with a dehydrating agent. The compound of the formula (VII) is commercially available in part, and can also be produced by treating the acetyl derivative, which is a synthetic intermediate of the formula (III), with formic acid and then performing a demethylation reaction.

The monoester (IX) of dicarboxylic acid can be directly esterified from dicarboxylic acid, esterified formylcarboxylic acid and then oxidized formyl group to give carboxylic acid, or a method such as introducing a carboxyl group into the ester. It can be manufactured.

Table 1 shows the transition temperature, the direction of the induced helix, and the direction of the spontaneous polarization of typical compounds of the formula (I) thus produced.

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.

In Table 1, C is a crystalline phase, SX is a chiral smectic phase whose assignment is unclear, SA is a smectic A phase, I
Each represents an isotropic liquid phase.・ Indicates that the phase exists, − indicates that the phase does not exist (or cannot be confirmed), the number on the right side of ・ indicates the transition temperature from the phase to the higher temperature phase, Indicates that the phase is monotropic. Further, the “helical direction” refers to the helical direction induced when added to a liquid crystal exhibiting a nematic phase. Also, * indicates that the phase can be confirmed under rapid cooling, but the transition temperature cannot be accurately measured due to crystallization. For No. 1 and No. 3 compounds, 10 ° ~
It is around 15 °.

Indicates that the melting point is unknown because it does not crystallize even if left to cool for a long time.

The structurally greatest feature of the compound of the formula (I) of the present invention is that it has two asymmetric carbon atoms in the molecule, and these are present separately on both sides of the core.

On the other hand, the 2-alkoxypropanoyloxy group is derived from lactic acid and its ester, and its steric configuration is (R) or (S). The other 1-methylalkoxycarbonyl group is derived from an optically active 2-alkanol, and the configurations thereof can be those of (R) and (S). Liquid crystalline compounds containing these optically active groups are known to exhibit a large spontaneous polarization, and in the former case, according to the studies by the present inventors, 100-150 nC
/ cm ^2, the latter in also, the value of 100nC / cm ² before and after (11th liquid crystal debate Proceedings P172) has been confirmed. However, as described above, it is desirable to use these optically active liquid crystal compounds by adding a small amount of about 5 to 30% to the SC ^host liquid crystal composition, and in that case, the spontaneously generated SC ^* liquid crystal composition is obtained. The polarization value becomes extremely small. Therefore, 100
A spontaneous polarization of ~ 150 nC / cm ² was not sufficient. In addition, these optically active liquid crystal compounds also had a strong helical twisting power.

We have found that 2-alkoxypropanoyloxy groups When the direction of spontaneous polarization of (S) -2-methylbutyl p-decyloxybenzylidene aminocinnamate (DOBAMBC), which is a ferroelectric liquid crystal having a well-known direction of spontaneous polarization derived from, is taken as ^{* When the} absolute configuration is (S), it is (R), and the twist direction of the induced helix is right-handed in (S), left-handed in (R), and 1-methylalkoxycarbonyl. Basis The direction of spontaneous polarization derived from is in the case where the absolute configuration of C ^** is (S), in the case of (R), and in the direction of the twist of the induced helix is left-handed in (S), and right-handed in (R). In a compound containing both a 2-alkoxypropanoyloxy group and a 1-methylalkoxycarbonyl group in the same molecule, due to the combination of the configurations of C ^* and C ^** , that is, ( In the case of (S) and (S), or (R) and (R), the torsional forces may be canceled out and become small, and the natural polarization may be added to obtain a very large value. This is the result of the invention.

Since the compound of formula (I) of the present invention does not always show a stable SC ^* phase in a single compound, SC showing an SC phase
The spontaneous polarization of the SC ^* liquid crystal composition obtained by adding to the host liquid crystal composition was measured, and this value was compared with the SC ^* liquid crystal composition similarly prepared from the SC ^* compound having a known spontaneous polarization. For example, 4 '-[(S) -2-methylbutanoyloxy] biphenyl-4-carboxylic acid 4-[(S) -1-methylheptyloxy] phenyl was previously developed by the present inventors.
A compound that exhibits the SC ^* phase and is T _C -T (T _C is SC ^*
It is a compound showing spontaneous polarization of 110 nC / cm ² at 25 ° of the maximum phase temperature), which is 10% (weight percentage) in a pyrimidine-phenylbenzoate SC liquid crystal composition (hereinafter referred to as SC host liquid crystal). The same applies hereinafter) The spontaneous polarization of the added SC ^* liquid crystal composition at T _C -T = 25 ° was 1.6 nC / cm ² . In contrast, 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4-[(S), which is one of the compounds of the present invention,
SC-comprising 10% of -1-methylheptyloxycarbonyl] phenyl (the compound of No. 1 in Table 1) ^*
The spontaneous polarization at T _C −T = 25 ° was 8.7 nC / cm ² , which was a very large value of 5 times or more.

By measuring the spontaneous polarization of the SC ^* liquid crystal composition obtained by changing the added concentration of this compound and extrapolating from these values,
The spontaneous polarization induced by this compound is
The size was equivalent to 400 to 500 nC / cm ² .

On the other hand, 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4-[(R) -1-, which is a compound in which the directions of spontaneous polarization derived from both optically active groups are different from each other Methylheptyloxycarbonyl]
For phenyl (No. 3 compound in Table 1), an SC ^* liquid crystal composition containing 10% was prepared in the same manner, and its spontaneous polarization at T _C −T = 25 ° was extremely small and was 0.2 nC / cm ² or less. Met.

The SC host liquid crystal is 10% by weight. 10% by weight 10% by weight 10% by weight 24% by weight 27% by weight 6% by weight And 3% by weight It consists of

Next, the helical pitch in the N ^* phase of the SC ^* liquid crystal composition comprising 85% of the above SC host liquid crystal and 15% of the compound No. 1 in Table 1 is 0.5 ° high temperature side of the N ^* -SA transition point. At 1.67 μm
In a left-handed, in the SC matrix liquid crystal 90% and SC ^* liquid crystal composition comprising a compound of 10% Table 1 Compound No.5, 2.40
It was a left-handed micrometer. On the other hand, the SC ^* liquid crystal composition consisting of 90% of the above SC host liquid crystal and 10% of the compound No. 3 in Table 1 in which the directions of the helix do not cancel out, the right-handed pitch and the pitch are small at 0.83 μm, The effect of reversing the directions of the two is clearly visible.

From the above results, the asymmetric carbons C ^* , C in the two optically active groups
Table 2 summarizes the absolute configuration of ^** , the direction and size of its spontaneous polarization, and the direction and size of the spiral pitch.

When the absolute configurations of C ^* and C ^** are combinations of (R), (R) and (R), (S), they are (S), (S) and (S), (R), respectively. It is self-evident that both the combination and the spontaneous polarization spiral pitch are different only in the directions and the sizes are equal, and it is sufficient to study the combination of the former two.

 The results shown in Table 2 show the following.

(1) The direction of spontaneous polarization is determined by the absolute configuration of the asymmetric carbon C ^* of the 2-propoxypropanoyloxy group.
It is considered that this is because the spontaneous polarization induced by the 2-propoxypropanoyloxy group is larger than the spontaneous polarization induced by the 1-methylheptyloxycarbonyl group.

(2) The direction of the helix is determined by the absolute configuration of the asymmetric carbon C ^** of the 1-methylheptyloxycarbonyl group.
It is considered that the helical twisting force induced contrary to (1) is larger than the 2-propoxypropanoyloxy group.

Thus, by changing the combination of the absolute configurations of C ^* and C ^** , it is possible to easily obtain the SC ^* liquid crystal composition in which the value of the spontaneous polarization and the direction of the spiral pitch are arbitrarily combined. This is extremely valuable in purifying an SC ^* liquid crystal composition having excellent responsiveness and orientation.

Now, one of the preferable combinations of C ^* and C ^** is
(S), (S), but the value of spontaneous polarization is large at this time. The direction is, and the spiral pitch is left-handed and relatively large, but it may not be sufficient. In such a case, a small amount of a compound having a right-handed helical pitch may be added, and the right-handed compound of the helix has a spontaneous polarization direction of, or If the value is small, there is no problem. In particular, 4'- which is a compound showing strong spontaneous polarization found by the present inventors.
[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4-[(R) -1-methylheptyloxy] phenyl {Japanese Patent Application No. 62-204833 spontaneous polarization 420n
C / cm ² (T _C −T = 10 °), spiral pitch right-handed} or a similar compound can be used to adjust the spiral pitch to a large value without lowering the spontaneous polarization value. is there.

In general, the introduction of a branching group into the side chain of a liquid crystal molecule lowers the liquid crystallinity and lowers its phase transition temperature, but in the compound of formula (I) of the present invention, it is divided into both side chains. Since a branch methyl group is present, its phase transition temperature is considerably lower than that of the one having a similar skeletal structure, and the liquid crystallinity by itself is from 3 rings of m + n = 3. It is difficult to show a liquid crystal phase by itself.

However, since the compound of the formula (I) of the present invention is effectively added to the SC compound or composition which is the base to prepare an SC ^* liquid crystal composition and used, there is no great influence. In particular, many compounds (I) of the formula (I) of the present invention show a chiral smectic phase even in a low temperature range SC ^*.
This is advantageous because T _C is not lowered so much during the preparation of the liquid crystal composition.

Now, SC to be used by mixing with the compound of formula (I) of the present invention
Examples of the liquid crystal compound or composition include a phenyl benzoate-based compound (A) and a pyrimidine-based compound (B) as shown below in the bicyclic type. A: (R ₃ and R _{4 each} 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 are the same as above.) Any compound represented by the general formula C including A and B can be used for this purpose.

C: (R ₃ and R ₄ are the same as above, Z ₁ is -COO-, -OCO-,
_{-CH 2 O -, - OCH 2} -, - CH 2 CH 2 -, - C≡C-, or represents a single crystal, Each independently, Alternatively, it represents a halogen-substituted product thereof. Further, in order to extend the temperature range of the SC ^* phase of these compositions to a high temperature range, a tricyclic compound can be used. This tricyclic compound can be generally represented by Formula D.

D: (R ₃ and R ₄ are the same as above.

as well as Alternatively, these halogen-substituted compounds are represented, and Z ₁ and Z ₂ are each independently -COO-, -OCO-, -CH ₂ O-, -OCH _{2
-, - CH 2 -CH 2 -} , - C≡C-, or represents a single crystal), but these may be used alone, since the wider temperature range is preferable to use as the above two-component compositions are obtained It is convenient. In addition, compounds other than (A) to (D) can be used in the same manner as long as they are compounds in which the side chain alkyl group is linear and exhibits an SC phase. Compounds shown in (A) to (D), or compounds other than (A) to (D), which do not themselves exhibit an SC phase, or low viscosity, liquid crystal compounds For example, addition to reduce the viscosity of the composition is an effective method for increasing the response.

The obtained liquid crystal compound or composition can be used as a liquid crystal display cell by forming a thin film having a uniform thickness (about 1 μm to 20 μm) between two transparent electrode plates.

In the display cell, the molecules of the liquid crystal need to be monodomains in which the molecular major axis 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. A method of gradually cooling from the organic liquid crystal phase (I) to the liquid crystal phase and orienting the liquid crystal phase is generally adopted.

Particularly recently, in a cell in which a liquid crystal showing a phase sequence of an isotropic liquid phase (I) → a chiral nematic phase (N ^* ) → a smectic A phase (SA) → a chiral smectic C phase (SC ^* ) is subjected to an alignment treatment. In particular, a method of orienting by increasing the helical pitch of the N ^* phase is often used,
SC containing about 10 to 30% of the compound of formula (I) of the present invention
^{* Even in the case of the} liquid crystal composition, a uniformly aligned monodomain cell can be easily obtained by the same method.

[Examples] The present invention will be specifically described below with reference to Examples, but of course, the gist and the scope of application of the present invention are not limited by these Examples.

Example I 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4-
Synthesis of [(S) -1-methylheptyloxycarbonyl] phenyl 1-a 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid Synthesis (S) -ethyl lactate 20.0 g, 45.0 g of propyl iodide and 30.0 g of silver oxide were stirred in 100 ml of dimethylformamide for 40 hours. The insolubles were separated, water was added to the solution, and the mixture was extracted three times with hexane. After dehydration of the hexane layer, the organic solvent was distilled off under reduced pressure to give ethyl (S) -2-propoxypropionate.
20.0 g was obtained. (18.0 g) was stirred in 100 ml of a 5N aqueous sodium hydroxide solution for 6 hours, and then adjusted to pH 3 to 4 with dilute sulfuric acid under ice-cooling. After extraction with ether several times, the mixture was dehydrated and the ether was distilled off to obtain 10.2 g of (S) -2-propoxypropionic acid. To this whole amount, 20 ml of thionyl chloride and 0.5 ml of pyridine were added, and the mixture was heated under reflux for 2 hours.
After distilling off excess thionyl chloride from the reaction mixture under reduced pressure, benzene was added to the reaction mixture to dissolve it, the insoluble matter was separated, and then benzene was distilled off from the liquid to obtain an oily (S)-
10.5 g of 2-propoxypropionic acid chloride was obtained.

5.27 g of this acid chloride was dissolved in 35 ml of pyridine and 20 ml of methylene chloride to prepare 4'-hydroxybiphenyl-4-.
Add dropwise to 7.06 g of carboxylic acid, and at the reflux temperature 6 after completion of the addition.
Allowed to react for hours. After completion of the reaction, a small amount of ethanol was added to esterify the unreacted acid chloride, and then diluted hydrochloric acid was added to make it weakly acidic, followed by extraction with ether. A mixed solvent of n-hexane and ether was added to the crude crystals obtained by distilling off the solvent, and the mixture was heated to reflux to remove insoluble 4'-hydroxybiphenyl-4-carboxylic acid. And the precipitated crystals were collected. Most of the diester compound remained in the liquid. Repeat this operation,
4 '-{(S) -2-propoxypropanoyloxy}
4.48 g of white crystals of biphenyl-4-carboxylic acid were obtained.

This compound showed a liquid crystal phase. Its melting point was 155 ° C and its clearing point was 220 ° C.

1-b Synthesis of title compound 15 ml of thionyl chloride was added to 4,48 g of the carboxylic acid obtained in 1-a, and 2 ml of pyridine was added with stirring. After dissolution, 4
The mixture was heated to 0 to 50 ° C and reacted for 3 hours. Excess thionyl chloride was distilled off, and toluene was added to the residue, followed by thorough stirring. After insoluble matter was removed in excess, the solvent was distilled off again to obtain 4.50 g of oily 4 '-{(S) -2-propoxypropanoyloxy} biphenyl-4-carboxylic acid chloride.

210 mg of this acid chloride was dissolved in 5 ml of methylene chloride, and 1-methylheptyl (S) -4-hydroxybenzoate was added to it.
Add 157 mg of 5 ml methylene chloride solution and add pyridine 0.
5 ml was added and reacted at 35 ° C. for 3 hours. After cooling down, ether 1
00 ml was added, and the mixture was washed successively with 10% aqueous hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution, water and saturated brine.

After dehydration with anhydrous sodium sulfate, the solvent was distilled off, and the obtained composition was purified by silica gel column chromatography (developing solvent: hexane-ether mixed system). Further recrystallize from ethanol to give 127m of white crystal of the title compound.
got g.

This compound exhibited liquid crystallinity. Its phase transition temperature is first
These are summarized in the table.

[Examples 2 and 3] In Example 1, (S) -1-methylheptyl 4-
Instead of hydroxybenzoate, (S) -1-methylheptyl 2-fluoro-4-hydroxybenzoate,
Or, in the same manner except using (R) -1-methylheptyl 4-hydroxybenzoate, 4′-
[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 3-fluoro-4-[(S) -1
-Methylheptyloxycarbonyl] phenyl (Example 2), and 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4-[(R)].
-1-Methylheptyloxycarbonyl] phenyl (Example 3) was obtained.

Example 4 Synthesis of 4 '-[(S) -1-Methylheptyloxycarbonyl] biphenyl-4-yl 4-[(S) -2-propoxypropanoyloxy] benzoate As an intermediate of 1-a 4.96 g of the obtained (S) -2-propoxypropionic acid chloride and 4-hydroxybenzoic acid were similarly reacted to obtain 3.45 g of white crystals of 4 [(S) -2-propoxypropanoyloxy] benzoic acid. It was
Melting point 84 ° 4-[(S) -2-propoxypropanoyloxy] benzoic acid 2.45 g is reacted with thionyl chloride 10 ml pyridine 0.2 ml to give 4-[(S) -2-propoxypropanoyloxy] benzoic acid chloride. Obtained 2.61 g.

150 mg of this acid chloride and (S) -1-methylheptyl 4'-hydroxybiphenyl-4-carboxylate 19
5 mg was reacted in the same manner as 1-b, purified by column chromatography (developing solvent: hexane-chloroform mixed system), and recrystallized from ethanol to obtain 227 mg of the title compound as white crystals.

Example 5 Synthesis of 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-yl 4-[(S) -1-methylheptyloxycarbonyl] benzoate 5-a 4'-[( Synthesis of S) -2-propoxypropanoyloxy] biphenyl-4-ol 2.70 g of 4,4'-biphenol was dissolved in 14 ml of pyridine and 6 ml of methylene chloride. 1-a was added to this solution at reflux temperature.
1.10 g of the (S) -2-propoxypropionic acid chloride obtained in the above was dissolved in 8 ml of methylene chloride and added dropwise. After completion of dropping, the mixture was stirred under reflux for 4 hours. After cooling, ether was added, and the mixture was washed with 10% hydrochloric acid water, water, and saturated saline. After dehydration with anhydrous sodium sulfate, the solvent was distilled off to obtain crude crystals, which were subjected to column chromatography (developing solvent: hexane-
1.32 g of 4 '-{(S) -2-propoxypropanoyloxy} biphenyl-4-ol after purification with ethyl acetate)
I got

This compound could be recrystallized from n-hexane and its melting point was 120 °.

5-b Synthesis of the title compound: 7.50 g of terephthalaldehyde acid, 20 ml of thionyl chloride,
And 1 ml of pyridine were added, and the mixture was stirred with heating. After forming a homogeneous solution, the mixture was stirred for 4 hours at the reflux temperature and then left to cool. Excess thionyl chloride was distilled off under reduced pressure, toluene was added, and the insoluble matter was separated. Toluene was distilled off to obtain 7.91 g of oily terephthalaldehyde chloride.

3.51 g of this acid chloride was added to (S) -2- in the presence of pyridine.
Reaction with 2.86 g of octanol in methylene chloride gave 5.71 g of a crude oily product of terephthalaldehyde acid and (S) -1-methylheptyl ester. This was dissolved in 40 ml of acetic acid, and 2.5 g of chromic anhydride dissolved in 2.5 ml of water and 5 ml of acetic acid was added dropwise at 50-60 ° C. After 1 hour, the reaction mixture was transferred to ice water, the white precipitate formed was taken, and impurities were removed by column chromatography to obtain 4-[(S) -1-methylheptoxycarbonyl] benzoic acid. This was treated with thionyl chloride to obtain 4 [(S) -1-methylheptoxycarbonyl] benzoic acid chloride.

To 340 mg of this acid chloride was added 4 '-[(S) obtained in 5-a.
-2-propoxypropanoyloxy] cobiphenyl-
350 mg of 4-ol was added as a solution of 10 ml of methylene chloride, 1 ml of pyridine was further added, and the mixture was reacted at reflux temperature for 2 hours. Then, the same treatment and purification as in Example 1 were carried out to obtain 250 mg of the title compound.

[Examples 6 and 7] 4 '[(S) -2-obtained as an intermediate of Example 1-a
Propoxypropanoyloxy] piphenyl-4-carboxylic acid chloride is converted into (S) -2-octanol or (S).
-2- (S)-by reacting with hexanol
4 '-[(S) -1-Methylheptyloxycarbonyl] biphenyl-4-yl 2-proxypropionate (Example 6) or 4'-[(S) -2-propoxypropionate Each compound of -1-methylpentyloxycarbonyl] biphenyl-4-yl (Example 7) was obtained.

[Example 8] Of the phenyl benzoate compounds represented by A as an example of the bicyclic SC liquid crystal compound or mixture, R ₃ and R ₄ are both alkoxy 4 components (R ₃ = nC ₁₀ H ₂₁ O-, R ₄ = n-
C ₈ H ₁₇ O-, 10 _{wt%; R 3 = n-C} 9 H 19 O-, R 4 = n-C 6 H 13 O
-, 10 _{wt%; R 3 = n-C} 8 H 17 O-, R 4 = n-C 10 H 21 O-, 10
_{Wt%; R 3 = R 4 =} n-C 8 H 17 O-, 10 wt%) and pyrimidine 4 components shown in _{B (R 3 = n-C} 8 H 17 -, R 4 = n-C 10 H _{twenty one}
O-, 24 _{wt%; R 3 = n-C} 8 H 17 -, R 4 = n-C 9 H 19 O-, 27 _{wt%; R 3 = n-C} 8 H 17 -, R 4 = n- C ₆ H ₁₃ O-, ₆ wt%; R ₃ =
_{n-C 9 H 19 -,} R 4 = n-C 9 H 19 O-, was prepared SC mother liquid crystal consisting of 3 wt%). This SC host liquid crystal showed an SC phase at 65 ° C. or lower, an SA phase up to 67 ° C. and an N phase up to 72 ° C. The melting point was 5 ° C.

This SC host liquid crystal 85.0% and the compound obtained in Example 1 15.0%
A SC ^* liquid crystal composition consisting of and showed a SC ^* phase at 3.54 ° C or lower, an SA phase at 69 ° C or lower, and an N ^* at 70.5 ° C or lower ^.
It showed a phase and became an isotropic liquid phase at higher temperatures. The helical pitch of the N ^* phase of this SC ^* liquid crystal composition at 69.5 ° C. was 1.67 μm in the left-handed direction. The spontaneous polarization of this SC ^* liquid crystal composition is 13.5nc / cm ² , 30 ° C at 34 ° C (T-Tc = 20 °).
Was 15.5nc / cm ² at 14.8nc / cm ^2, 26 ℃ at (T-Tc = 25 °).

Example 9 An SC ^* liquid crystal composition was prepared which was composed of the same SC host liquid crystal 85.0% as in Example 8 and the compound 15.0% obtained in Example 3, and the phase transition temperature thereof changed from that of Example 1. There was no However, the N ^{* of} this SC ^* liquid crystal composition at 69.5 ° C.
The helical pitch of the phase was 0.83 μm for right-handed winding, and its spontaneous polarization was extremely small at 0.2 nc / cm ² or less even at 25 ° C.

Example 10 was the Example 8 consisting of 15.0% compound obtained in Example 5 and SC mother liquid crystal 85.0% similar to the SC ^* liquid crystal compositions were prepared, the SC ^* phase at 58 ° C. or less, 60 ° C. or less The SA phase showed an N ^* phase at 68.5 ° C or lower, and became an isotropic liquid crystal phase at a temperature higher than that. The helical pitch of the N ^* phase of this SC ^* liquid crystal composition at 60.5 ° C. was 2.40 μm, and the spontaneous polarization was 38 ° C. (T−Tc = 20
It was even greater than for ° 16.4nc / cm ^2, 27 compound obtained in 17.9nc / cm ² as in Example 1 at ° C..

[Example 11] The same SC matrix liquid crystal as in Example 8 (81.5%) was used, and the compound obtained in Example 1 (7.0%) and 4 '-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid 4 were used. −
[(R) -1-Methylheptyloxy] phenyl 11.5%
SC ^* liquid crystal composition was prepared.

This SC ^* liquid crystal composition has an SC ^* phase of 65.5 ℃ at 58 ℃ or below.
The SA phase was shown below, and the N ^* phase was shown at 69 ° C. or lower.

The SC ^* liquid crystal composition had a large helical pitch of N ^* phase at 66 ° C. of 26 μm. Spontaneous polarization is 38 ° C
(T-Tc = 20 °) 16.0nc / cm ² , 33 ° C (T-Tc =
Was 18.5nc / cm ² in at 17.2nc / cm ^2, 25 ℃ 25 °).

Example 12 4-decylbenzoic acid 4- [5-octylpyrimidine-
2-yl] phenyl 35% 2- (4-hexylbenzyloxy) -5- (4-peptylphenyl) pyrididine 15% 4-decylbenzoic acid 4-octylphenyl 15% 4-decylbenzoic acid 4-heptylphenyl 15 % Of the compound obtained in Example 1 in the SC liquid crystal composition consisting of 4%
10% of 4-[(R) -1-methylheptyloxy] phenyl 4-[(S) -2-propoxypropanoyloxy] biphenyl-4-carboxylic acid and 4-[(S) -2-methylbutyloxy] 4-octyloxyphenyl benzoate 5% (used for fine adjustment of pitch) was added to obtain an SC ^* liquid crystal composition.

This SC ^* liquid crystal composition showed an SC ^* phase at 47 ° C. or lower, an SA phase at 52 ° C. or lower, and an N ^* phase at 73 ° C. or lower, and became an isotropic liquid phase at a temperature higher than that.

The helical pitch in the N ^* phase of this SC ^* liquid crystal composition is
16 μm at 59 ° C, and extremely large measurement at 54 ° C or less. Also, the spontaneous polarization at 27 ° C (T-Tc = 20 °) is
It was 14.8 nc / cm ² .

[Example 13] The SC ^* liquid crystal composition obtained in Example 8 was heated to 75 ° to form an isotropic liquid phase, and this was mixed with two glass transparent electrodes (one of which was 1 μm) through a spacer having a thickness of 2.2 μm. The sheet was filled between the polyimide coating and the rubbing orientation treatment) to form a thin film cell. This thin film cell is gradually cooled at a rate of 5 ° per minute to orient the N ^* phase and SA phase and SC at 54 ° C or less.
^* I was able to obtain the phase monodomain.

A 22 V, 50 Hz rectangular wave was applied to this cell, and the transmitted light intensity was measured. As a result, a fast response performance of 46 μsec at 30 ° C. and 51 μsec at 26 ° C. was shown. The tilt angle at this time is
They were 21.7 ° and 23.3 °, respectively.

Example 14 Using the SC ^* liquid crystal composition obtained in Example 9, a cell was prepared in the same manner as in Example 13. (Thickness 21 μm) In this cell
When a 21 V 50 Hz rectangular wave was applied and the response time was measured, it was 1.13 ms at 28 ° C., which was considerably slower than that in Example 13. The tilt angle at this time was 18.5 °.

Example 15 Using the SC ^* liquid crystal composition obtained in Example 10, a cell was prepared in the same manner as in Example 13. (Thickness 2.5 μm) 2 in this cell
When a rectangular wave of 5V 50Hz was applied and the response time was measured, it showed extremely fast response performance of 37 μs at 27 ° C. The tilt angle at this time was 29.4 ° C.

Example 16 A cell was prepared in the same manner as in Example 13 using the SC ^* liquid crystal composition obtained in Example 11. (Thickness 2.5 μm) 2 in this cell
Applying a square wave of 3V50Hz and measuring the response,
It showed a fast response performance of 43 μs at 25 ° C. The tilt angle at this time was 28.3 °.

Since this SC ^* liquid crystal composition has a large pitch of the N ^* phase near the N ^* → SA transition point, the orientation is extremely excellent.
A higher contrast was obtained than the cells of Examples 13-15.

[Example 17] A cell was similarly prepared using the SC ^* liquid crystal composition obtained in Example 12. (Thickness: 2.2 μm) A rectangular wave of 22 V and 50 Hz was applied to this cell, and the response time was measured and found to be 91 μsec at 25.5 ° C. The tilt angle at this time was 23.7 °. The contrast of this cell was extremely high as in Example 16.

〔The invention's effect〕

The compound of the present invention has a spontaneous polarization larger than that of a conventionally known ester-based strongly-inductive liquid crystal compound when mixed into an SC ^* liquid crystal composition, and also has a sufficiently large helical pitch. When used as a SC ^* liquid crystal composition by adding it to a liquid crystal compound or composition, the spiral pitch adjustment is extremely easy.

In addition, the compound of the present invention, as shown in Examples,
It is easy to manufacture industrially and is colorless in itself.
It has excellent chemical stability against light, moisture, heat, etc., and is very practical.

Furthermore, the ferroelectric liquid crystal compound and the composition containing the same according to the present invention have a reaction rate which is lower than that of a conventional nematic liquid crystal.
It is extremely large, 100 times or more, and is extremely useful as an optical switching element for display.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C09K 19/20 9279-4H C09K 19/20 G02F 1/13 500 G02F 1/13 500 (72) Invention Person Masashi Osawa 76-2, Castle, Sakura City, Chiba Prefecture

Claims (1)

(57) [Claims] 1. A general formula (Wherein, R ₁ represents an alkyl group having _{1 to} 16 carbon atoms,
R ₂ represents an alkyl group having 2 to 16 carbon atoms, and Y is Or a single bond, m and n are each independently O.
Or represents 1. Each independently represents a 1,4-phenylene group or a 1,4-phenylene group in which 1 to 2 hydrogen atoms are substituted with a fluorine atom, a chlorine atom, a methyl group or a cyano group,
C ^* and C ^** are each independently (R) or (S)
Represents a configurational asymmetric carbon atom. ) A compound represented by: