JPH0362885A - Optically active compound, liquid crystal composition and liquid crystal element containing the same - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal composition, capable of exhibiting a smectic C phase within a wide temperature range with ambient temperature as the center and high-speed responsiveness by adding a specific optically active compound to a (non)chiral liquid crystal compound. CONSTITUTION:The objective composition obtained by adding an optically active compound expressed by the formula (R is 1-15C alkyl; * indicates that C thereof is asymmetric carbon atom) to a (non)chiral liquid crystal compound. The aforementioned compound is synthesized by, e.g. reacting an optically active 1-trifluoromethyl-3-phenyl-2-propenyl alcohol with sodium hydride, converting the aforementioned compound in to a sodium alkoxide, on the other hand, reacting an alkoxycarboxylic acid with phosphorus pentachloride, converting the above-mentioned carboxylic acid into a carboxylic acid chloride and then reacting the aforementioned sodium alkoxide with the above-mentioned carboxylic acid chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention relates to optically active compounds and their uses, and more specifically, to the use of ferroelectric liquid crystal compositions containing at least one of these optically active compounds. Related to liquid crystal elements.

(b) Prior Art The liquid crystal display element most widely used at present is one that utilizes a nematic phase, but it has the drawback that it is difficult to display large capacity such as 100OX100O line. For example, in ordinary twisted nematic (TN) type liquid crystal display elements, the contrast decreases as the number of lines increases, so it is virtually impossible to create a high-capacity display element with good appearance, such as 1000 x 1000 lines. .

Super twisted nematic (STN) type liquid crystal display elements and double super twisted nematic (DSTN) type liquid crystal display elements have been developed to improve the drawbacks of TN type liquid crystal display elements, but as the number of lines increases, the contrast decreases. It has the disadvantage of decreasing response speed, and at present, the limit level is to achieve a display capacity of about 100 x 800 lines using the upper and lower division driving method with a duty of 1/loo. On the other hand, a thin film transistor (T
An active matrix type liquid crystal display element has also been developed, and it is technically possible to display large-capacity displays such as 1000 x 1000 lines, but the manufacturing process is long and the yield is low, making the manufacturing cost extremely high. It has the disadvantage of being

Ferroelectric liquid crystal display elements (Il,
A. C1ark et al., Appl., Phy.
sLeft, 36.899 (1980)). This display method utilizes chiral smectic C phase, chiral smectic ■ phase, etc. which are ferroelectric liquid crystals. Since it is a method that utilizes memory properties, it is possible to increase the display capacity by improving response speed, and since it does not require active elements such as thin film transistors, manufacturing costs do not increase. In addition, ferroelectric liquid crystal elements have the advantage of wide visual field.
It is highly promising as a device for large-capacity display capable of displaying 1000 x 1000 lines or more.

(c) Problems to be Solved by the Invention It goes without saying that the liquid crystal material used in the ferroelectric liquid crystal display using the smectic C phase mentioned above must exhibit the smectic C phase in a wide temperature range centered around room temperature. In addition, it is necessary to satisfy various other conditions.

First, high-speed response is required as a device characteristic in order to perform large-capacity display, and from this viewpoint, liquid crystal materials are required to have high spontaneous polarization and low viscosity.

In addition, in order to obtain good alignment and bistability when applied to a liquid crystal cell, IAC (Isotropic S
mectic A-Smectic C) or INA
C(ls.

tropic-Nematic-Smectic A-
It is necessary for the liquid crystal material to exhibit a phase series called smectic C), and a nematic phase and a smectic C).
It is necessary that the helical pitch of the phase is sufficiently long compared to the cell thickness. Furthermore, a large value for the tilt angle, which is related to the contrast and brightness of product display, is desired.

However, it is currently impossible to satisfy all the desired conditions with a single compound, and usually ? jt number of compounds are mixed and put into practical use as a liquid crystal composition. In order to prepare a liquid crystal composition that satisfies practical conditions, a large number of single crystalline compounds with diverse properties are required, and in some cases, compounds that do not themselves exhibit liquid crystallinity are useful as components of liquid crystal compositions. There is a possibility that it will.

This invention was made under these circumstances, and it provides a novel optically active compound that enables improvement of the response characteristics of a ferroelectric liquid crystal composition, and a novel optically active compound containing the same that has a wide operating temperature range.
The object of the present invention is to provide a ferroelectric liquid crystal composition and a ferroelectric liquid crystal element that can obtain good alignment and exhibit high-speed response at room temperature.

(d) Means and operation for solving the problems Thus, according to the present invention, the following general formula (I): (wherein R represents an alkyl group having 1 to 15 carbon atoms, and * indicates that the carbon atom is Provided is an optically active compound represented by the following.

-5= The compound of the above formula (1) (hereinafter referred to as compound (I)) is
This is a compound that has not been described in any literature.

The above compound (1) has a cis form and a trans form,
All are included in the compounds of this invention.

In this invention, the "alkyl group having 1 to 15 carbon atoms" in the definition of compound (I) above includes methyl, ethyl, propyl, l-propyl, butyl, l- or 2-methylpropyl, L-butyl, pentyl. , l- or 2-methylbutyl, hexyl, 1- or 3-methylpentyl, heptyl, l- or ylmethylhexyl, octyl, l-methylhebutyl, nonyl, 1- or 6-methyloctyl, decyl, l-methylnonyl, Includes undecyl, tomethyldecyl, dodecyl, 1-methylundecyl, and the like.

The carbon chain of these alkyl groups may contain an asymmetric carbon.

Among the above compounds (T), the following compounds can be mentioned as preferable examples.

(Margin below) 6- etc.

Compound (1) can be made into a mesh as follows, for example. Optically active t-trifluoromethyl-3-phenyl-2-propenyl alcohol is converted to sodium alkoxide by reaction with sodium hydride (reaction formula (a)), while alkoxybiphenylcarboxylic acid is converted to sodium alkoxide by reaction with sodium hydride. The compound is converted into 7-licarboxylic acid chloride by reaction with (reaction formula (b)), and then the above-mentioned sodium alcokind is reacted with the above-mentioned carboxylic acid chloride.

RO-CI-Q-COOH ct5 RO-Q-Q-COCI (b) The above-mentioned optically active alcohol is described, for example, by Hisashi Tsukamoto, Take 1)
Mitsunori, Hayashi Okan, Takashi Yamazaki, Tomoya Kitazume, Proceedings of the 13th Fluorine Chemistry Symposium J (1988) 4 D 11
It can be synthesized according to 2.

Although compound (I) does not necessarily exhibit a liquid crystal phase, it can be used as a ferroelectric liquid crystal composition by adding an amount of a to a nonchiral smectic or chiral smectic liquid crystal compound or a mixture thereof.

Generally, in order to improve the response speed of a ferroelectric product, it is sufficient to have a group having a strong dipole moment near the asymmetric carbon. It is preferable that the free rotation of molecules is constrained (J, S, Pa
tel and J, W, Goodby, Optica
lEngineering, 26.373 (1987
), etc. are said.

The compounds of this invention have a strong dipole moment.
It is thought that the free rotation of the molecule is restricted because the group F is bonded to an asymmetric carbon and, moreover, a group having a double bond is bonded to an asymmetric carbon. Moreover, the compound (I
) has a structure that is bent at and near the asymmetric carbon moiety, and is expected to limit intermolecular rotation. therefore,
Compound (I) is expected to have potentially large spontaneous polarization, and it is thought that response characteristics can be improved by adding an appropriate amount to a liquid crystal compound exhibiting a smectic C phase or a mixture thereof.

Therefore, the present invention also provides a ferroelectric liquid crystal composition characterized in that the smectic liquid crystal compound or a mixture thereof contains at least one optically active compound represented by the chemical formula (r).

The above-mentioned smectic liquid crystal compounds include various compounds known in the art, and specific examples thereof include the following general formula (I
Examples include compounds represented by I), ([11), and (IV)].

R3-death ■-to Q-B-R, (II) R3-to ■-to〇-to○-B-R4 (1) R, -A-(◎) p-D-0
-(Cll)B-R4(IV) (In the above formula, A and B are each a single bond, or COO-, ~0CO-, -CI (=
CH-COO-, -0CO-CH=CH-, -0-.

It represents a group of s-, -ocoo- or -CO-. D and E are each a single bond, -COO-, -0CO-,
-CII=N-.

N=CH-, -CI(=CH(--CEC-, -CH=
CH-COO-, -0CO-CH=CH-, -CH2C
It represents a group of H2-, -0CH2-, -CI, O--CO8- or -5CO-. ■, @ and ○ are each independently a benzene ring, a nclohexane ring, a bicyclo[2,2
, 2] indicates a 6-membered ring group such as an octane ring, a pyranone ring, a pyrimidine ring, a pyranone ring, a pyridazine ring, a piveranone ring, a biran ring, a nooxane clohexane ring, and the hydrogen atom in these 6-membered ring groups is It may be substituted with a fluorine atom, a chlorine atom, a bromine atom, a cyano group, a nitro group, a lower alkyl group, a lower alkokene group, or deuterium. R3 and R4 each independently represent a linear or branched alkyl group having 1 to 15 carbon atoms, and an asymmetric carbon may be contained in the alkyl group. p represents an integer of 1 or 2. ) The above smectic liquid crystal compound is 2
More than one species can be mixed and used. In particular, it is preferable that the above-mentioned smectic liquid crystal compound be mixed appropriately so that it exhibits a smectic C phase near room temperature and has a phase series such as IAC'PINAC.

The content of compound (I) in the ferroelectric liquid crystal composition of the present invention containing the above smectic liquid crystal compound or a mixture thereof and the above compound (I) is usually 01 to 30% by weight.
If it is less than 601% by weight, the improvement in response is insufficient, and if it exceeds 30% by weight, the thermal stability of the smectic C phase is insufficient. It is not suitable for this reason.

Furthermore, the present invention can provide an fco liquid crystal element using the above ferroelectric liquid crystal composition between a pair of electrodes. This liquid crystal element can be constructed using materials known in the art as they are, except that the ferroelectric liquid crystal composition of the present invention is used as the liquid crystal composition. Such a liquid crystal element is particularly preferable not only as a product display element but also as, for example, a liquid crystal display.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereby.

(Left below) 1 (e) Examples Example 1 (S)-4°-n-octyloxy-biphenyl-4-
Carboxylic acid-1-trifluoromethyl-3-phenyl-
(trans)-2-propenyl ester [general formula (1)
0.5 g (1.5 mmol) of 4-n-octyloxy-biphenyl-4-carboxylic acid, 0.4 g of phosphorus pentachloride
(1.9 mmol) is added and heated to react. Phosphoryl chloride and excess phosphorus pentachloride were completely removed by distillation under reduced pressure, and 4°-n-octyloxy-biphenyl-
Carboxylic acid chloride was obtained.

Next, 0.3 g of (S)-1-)lifluoromethyl-3-phenyl(trans)-2-propenyl alcohol (
1.5 mmol) was dissolved in toluene LOxQ, and 0.05 g (2 mmol) of sodium hydride was added and reacted. Unreacted sodium hydride was removed by filtration to obtain sodium (S)-1-trifluoromethyl-3-phenyl-(trans)-2-propenyl alcohol.

Add the above acid chloride dissolved in toluene of 13- +2- I Ox (!), leave it at room temperature for 12 hours, heat it to 80°C, keep it there for 3 hours, and then cool it. Then add it to distilled water and add ether. The ether layer is washed with water and dried over sodium sulfate. The ether is distilled off, and the residue is purified by liquid chromatography (column/C18-silica, mobile phase solvent: methanol) to obtain the desired (S) -4'-
n-octyloquine-biphenyl 4-carboxylic acid-1-
) Lifluoromethyl-3-phenyl-(trans)-2
-propenyl ester was obtained.

The infrared absorption spectrum of the ester obtained above is shown in FIG. The melting point of this ester is 79°C, and the specific rotation is 10B.
, 0°. This ester does not exhibit a liquid crystal phase or can be used as a component of a liquid crystal composition.

Example 2 (R14°-n-octyloxy-biphenyl-4-carboxylic acid-1-trifluoromethyl-3-phenyl-(
cis)-2-propenyl ester [compound of R-C8HI7- in general formula N)] 14- In Example 1, (S)-1-trifluoromethyl3
-Phenyl-(trans)-2-propenyl alcohol 0
．． Instead of using 3g, (1,5mmol), (R
)-1 trifluoromethyl-3-phenyl-(ns)-
2-propenyl alcohol 0.3g (1.5mmol
) in the same manner as in Example I except that (R) −4°
-n-octyloxy-biphenyl-4-carboxylic acid-
1-trifluoromethyl-3-phenyl-(ns)-2
-propenyl ester was obtained.

The melting point of the ester obtained above was 70°C, and the specific optical rotation was 1850°. Although this ester did not show a product phase, it could be used as a liquid crystal composition. The external absorption spectrum is shown in Figure 2.

Example 3 Preparation of liquid crystal composition To 98 parts by weight of the non-chiral pyrimidine liquid crystal composition shown in Table 1 below, 2 parts by weight of the compound synthesized in Example 1 above was added to prepare liquid crystal composition (A). 15 Prepared.

[Table 1] This liquid crystal composition (A) exhibits a smectic C phase at room temperature, and its transition is 41'C68°C69°C 5c S A N I (
Here, Se, SA, N, and I represent a smectic C phase, a smectic A phase, a nematic phase, and an isotropic limb, respectively. )Met.

ITO films are formed on two glass substrates, and Si
A film was shaped with O, and a polyvinyl alcohol film was applied and rubbed.

Next, these two glass substrates were bonded together with a cell thickness of 2 μm, and the liquid crystal composition (A) was injected. After injection, heat the cell to 75 °C, where the liquid crystal composition changes to an isotropic liquid, and then heat the cell to 1 °C.
Good orientation was obtained by cooling to room temperature at /min.

This liquid crystal cell is installed between two orthogonal polarizers, and V
When a rectangular wave of pp=20V was applied, a change in transmitted light intensity was observed. The response speed determined by the change in transmitted light intensity was 190 μsec at 25°C, and the tilt angle was 10
．． It was 5”.

Example 4 In Example 3, a liquid crystal composition (B) was prepared in the same manner as in Example 3 except that the compound synthesized in Example 2 was used instead of the compound synthesized in Example 1.

This liquid crystal composition (B) exhibits a smectic C phase at room temperature, and its transition point is 44°C, 63°C, and 68°C.
c, SA+ N, and I represent smectic C phase, smectic A phase, nematic phase, and isotropic liquid, respectively. )Met.

Further, a liquid crystal element was prepared using this liquid crystal composition (B) in the same manner as in Example 3, and its response speed was measured to be 330 μsec at 25° C., and the tilt angle was 10.5'.
Met.

From the above examples, by adding the optically active compound represented by the general formula (I) to a non-chiral liquid crystal composition, it exhibits a smectic C phase in a wide temperature range centered on room temperature and exhibits high-speed response. A liquid crystal composition can be obtained.

(f) Effects of the Invention The optically active compound of the present invention has high spontaneous polarization and low viscosity, and by utilizing these properties, it is useful for various applications, especially for ferroelectric liquid crystal compositions. Useful for improving response speed and operating temperature range.

The smectic liquid crystal composition mixed with the optically active compound has good alignment, and can provide a high-contrast, bright, large-capacity ferroelectric liquid crystal element with a wide operating temperature range.

[Brief explanation of drawings]

FIGS. 1 and 2 are infrared absorption spectra of an optically active compound according to an example of the present invention.

Claims (1)

[Claims] 1. The following general formula (I): ▲ Numerical formula, chemical formula, table, etc. ▼ (I) (In the formula, R represents an alkyl group having 1 to 15 carbon atoms, and * represents the carbon atom. is an asymmetric carbon.) is an optically active compound represented by 2. A ferroelectric liquid crystal composition comprising a smectic liquid crystal compound or a mixture thereof and at least one optically active compound according to claim 1. 3. A liquid crystal element using the liquid crystal composition according to claim 2 between a pair of electrodes.