JPH04261162A - Optically active pyrazine compound and display element - Google Patents

Abstract

PURPOSE:To provide the subject compound capable of giving large area stable molecular orientation and useful as an antiferroelectric liquid crystal material having a three-stable state. CONSTITUTION:A compound of formula I (R<1> is 4-16C alkyl or alkoxy; R<2> is 4-12C alkyl; * exhibits to be optically active), e.g. (S)-5-(4-hexyloxyphenyl)-2- piperazine carboxylic acid 4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester. The compound is produced by reacting a compound of formula I with a compound of formula III, removing the benzyl group from the reaction product in the presence of Pd/charcoal as a catalyst, and subsequently reacting the product with a pyrazine carboxylic acid compound in the presence of a dehydration-condensing agent (e.g. dicyclohexylcarbonediimide) and a catalyst (e.g. N,N-dimethyl-4-aminopyridine) in a solvent such as methylene chloride.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The compound of the present invention is expected to be used as a liquid crystal compound, and is used for antiferroelectric liquid crystal materials exhibiting a chiral smectic CA phase having tristable states, and for liquid crystal displays using the same. It is related to the element.

0002

2. Description of the Related Art Currently, liquid crystal display elements are widely used as various display elements due to their low voltage drive performance, low power consumption, small size, and thinness.

Recently, high-speed response liquid crystal devices using ferroelectric smectic liquid crystals have been actively researched. Since ferroelectric smectic liquid crystals have spontaneous polarization, it is known that they have a large driving force when interacting with an electric field and exhibit high-speed response to changes in the electric field. Utilizing this high-speed response, research is progressing into display elements such as liquid crystal televisions, and optoelectronic elements such as optical printers and light valves.

Currently, most of the ferroelectric liquid crystal phases that are being used in these devices are chiral smectic C.
It attempts to perform display in a surface-stabilized ferroelectric liquid crystal mode, and uses two stable states that molecules can take.

However, in this surface-stabilized ferroelectric liquid crystal mode, it is difficult to obtain an ideal molecular orientation state called a monodomain state over a large area, and defects may occur or disorder of molecular orientation called twist. There is a problem in that it may cause

On the other hand, 4'-octyloxybiphenyl-4-carboxylic acid-4-[1 -(trifluoromethyl)heptyloxycarbonyl]phenyl ester (
Japanese Unexamined Patent Publication No. 2-160748) is known, and an element using a composition composed of a tricyclic ester compound as a liquid crystal display element (Japanese Unexamined Patent Application No. 1-213390) is known.

[0007]

SUMMARY OF THE INVENTION The present invention provides an antiferroelectric liquid crystal compound having tristable states that can obtain stable molecular alignment over a large area, which is difficult to achieve with conventional ferroelectric smectic liquid crystals. Conventionally known antiferroelectric liquid crystal compounds provide optically active compounds with different chemical structures and liquid crystal display elements using the same.

[0008]

[Means for Solving the Problems] The present inventors have conducted intensive studies to achieve the above object, and as a result, have completed the present invention. That is, the present invention provides the following general formula (1)

[C3
] [However, in the above general formula (1), R1 represents an alkyl group or an alkoxy group having 4 to 16 carbon atoms, and R2 is
It represents an alkyl group having 4 to 12 carbon atoms, and * represents optical activity. ] and a display element using the same.

The optically active compound according to the present invention is a compound useful as an antiferroelectric liquid crystal material exhibiting a chiral smectic CA phase having three stable states.

In the general formula (1), R1 has 4 to 1 carbon atoms;
Examples of the alkyl group of 6 include linear groups such as a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and a hexadecyl group. Alternatively, a branched alkyl group can be exemplified, and examples of the alkoxy group include a butyloxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, a dodecyloxy group, and a trioxyoxy group. Examples include linear or branched alkoxy groups such as a decyloxy group, a tetradecyloxy group, a pentadecyloxy group, and a hexadecyloxy group.

On the other hand, the alkyl group having 4 to 12 carbon atoms for R2 is a linear or , a branched alkyl group can be exemplified.

0012

[General Production Method] The compound represented by the general formula (1) of the present invention can be produced by the method shown below. The reaction formula is illustrated below, in which R1 and R2 are represented by the general formula (1)
This is the same as specified in .

[0013]

[Reaction process〓]

[C4]

[0014]

[Reaction step II]

[C5]

[0015]

[Reaction step III]

[C6]

[0016] Reaction step I uses toluene as a reaction solvent;
The reaction can be carried out using diethyl ether, tetrahydrofuran, etc. at a reaction temperature of -20 to 60°C.

Reaction step II is a debenzylation step, which can be carried out by known methods. For example, using palladium/charcoal as a catalyst and ethanol as a solvent,
This can be easily carried out by hydrogenation at normal pressure using acetic acid or the like.

In reaction step III, dicyclohexylcarbodiimide or the like is used as a dehydration condensation agent, and N,
By using an organic base such as N-dimethyl-4-aminopyridine and using methylene chloride, chloroform, etc. as a solvent, the compound of general formula (1), which is the object of the present invention, can be easily obtained.

The compound of the following chemical formula 7 used in reaction step III is also described, for example, in Proceedings of the Spring Annual Meeting of the Chemical Society of Japan, 4IIB0.
6 (1988).

[C7]

[0020]

[Examples of Compounds] Examples of the optically active compounds used in the present invention include the following. (S)-5-
(4-Hexyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(S)-5-(4-octyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(S)-5-(4-decyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

[
(S)-5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

[
(S)-5-(4-tetradecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(R)-5-(4-hexyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

(R)-5-(4-octyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

(R)-5-(4-decyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

[
(R)-5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

[
(R)-5-(4-tetradecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

(R)-5-(4-hexyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

[
(R)-5-(4-octyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

0
(R)-5-(4-decyloxyphenyl)-
2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

003
3] (R)-5-(4-dodecyloxyphenyl)-2
-Pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

0034
](R)-5-(4-tetradecyloxyphenyl)-
2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

(S)-5-(4-hexyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-octyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-decyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-tetradecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-hexylphenyl)-
2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

00
41] (S)-5-(4-octylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

[0042]
(S)-5-(4-decylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(S)-
5-(4-dodecylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(S)-5-(
4-tetradecylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylpentyloxycarbonyl)phenyl ester

(R)-5-(4
-Hexylphenyl)-2-pyrazinecarboxylic acid-4-
(1-trifluoromethylheptyloxycarbonyl)
phenyl ester

(R)-5-(4-octylphenyl)-2-pyrazinecarboxylic acid-4-(1-
trifluoromethylheptyloxycarbonyl) phenyl ester

(R)-5-(4-decylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

(R)-5-(4-dodecylphenyl)
-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

0
(R)-5-(4-tetradecylphenyl)-
2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

00
50] (R)-5-(4-hexylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

[0051](
R)-5-(4-octylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

(R)-5
-(4-decylphenyl)-2-pyrazinecarboxylic acid-
4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

(R)-5-(4-dodecylphenyl)-2-pyrazinecarboxylic acid-4-(1
-trifluoromethylnonyloxycarbonyl)phenyl ester

(R)-5-(4-tetradecylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylnonyloxycarbonyl)phenyl ester

(S)-5-(4-hexylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

(S)-5-(4-octylphenyl)
-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

[
(S)-5-(4-decylphenyl)-2-
Pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

005
8] (S)-5-(4-dodecylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

[0059]
(S)-5-(4-tetradecylphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylundecyloxycarbonyl)phenyl ester

[0060]

[Liquid crystal display element] The liquid crystal display element of the present invention is manufactured by injecting a liquid crystal compound into a cell obtained by laminating two glass substrates with transparent electrodes and alignment-treated surfaces with a spacer in between. This can be done by

[0061] For manufacturing the cell, conventional techniques for manufacturing a liquid crystal element using a liquid crystal compound having a chiral smectic C phase can be applied. For example, alumina beads, glass fiber, polyester film, etc. can be used as the spacer. In addition, as an alignment treatment material, PVA
, PI, SiO, SiO2, etc.

[0062]

Effects of the Invention The optically active compound according to the present invention has useful performance as an antiferroelectric liquid crystal material exhibiting a chiral smectic CA phase having a tristable state.

[0063] Therefore, a liquid crystal display element using this optically active compound as a liquid crystal material can obtain stable molecular orientation over a large area. It is also possible to display halftones using the three stable states. Such characteristics allow the liquid crystal display element of the present invention to be used in more ways than conventional products.

[0064]

EXAMPLES The present invention will be explained in more detail with reference to Examples below. In addition, the measurement of the phase transition temperature and the identification of the phase in the examples were carried out by DSC measurement and observation with a polarizing microscope.

Cry is a crystalline phase, SmCA* is a chiral smectic CA phase, SmA is a smectic A phase, Iso
represents the isotropic phase.

[0066]

[Example 1] (R)-5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester

(I) Production of (R)-4-benzyloxybenzoic acid-1-trifluoromethylheptyl ester

[
684 mg of 4-benzyloxybenzoic acid (3
．． After heating thionyl chloride (10 ml) under reflux for 3 hours, excess thionyl chloride was distilled off under reduced pressure to obtain 4-benzyloxybenzoic acid chloride. This product was not particularly purified and was used in the next step as a tetrahydrofuran solution. On the other hand, in a solution of 552 mg (3.0 mmol) of (R)-1,1,1-trifluoro-2-octanol in 15 ml of tetrahydrofuran, 132 mg of sodium hydride (3.3 mmol with a purity of 60%) was added.
The tetrahydrofuran solution of the alcoholate obtained by adding 1) was added dropwise to the previously obtained tetrahydrofuran solution of the chloride with stirring at room temperature over about 30 minutes, and the mixture was further stirred for 12 hours.

After the reaction was completed, 60 ml of water was added, followed by extraction with 90 ml of methylene chloride, and the organic phase was washed with 5% aqueous sodium bicarbonate and water, and then dried over anhydrous magnesium sulfate. After filtering off the desiccant, methylene chloride was distilled off to obtain a crude target product.

This product was purified by silica gel chromatography to obtain oily (R)-4-benzyloxybenzoic acid-1-trifluoromethylheptyl ester 105
7 mg (2.68 mmol) was obtained.

(II) Production of (R)-4-hydroxybenzoic acid-1-trifluoromethylheptyl ester

0
(R)-4-benzyloxybenzoic acid-1-trifluoromethylheptyl ester obtained in (I) 1
After dissolving 000 mg (2.54 mmol) in 20 ml of acetic acid, 5% palladium/charcoal 2 was added under hydrogen atmosphere.
80 mg at room temperature for 5 hours.

After the reaction was completed, palladium/charcoal was filtered off, and acetic acid was distilled off under reduced pressure to obtain a crude target product.

This product was purified by silica gel chromatography to obtain 726 mg of oily (R)-4-hydroxybenzoic acid-1-trifluoromethylheptyl ester.
(2.38 mmol) was obtained.

(III) (R)-5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid-4-(1-
Production of trifluoromethylheptyloxycarbonyl) phenyl ester

152 mg (0.50 mmol) of (R)-4-hydroxybenzoic acid-1-trifluoromethylheptyl ester obtained in (II), 212 mg of 5-(4-dodecyloxyphenyl)-2-pyrazinecarboxylic acid
(0.55 mmol) and 34 mg (0.27 mmol) of N,N-dimethyl-4-aminopyridine were dissolved in 10 ml of methylene chloride at room temperature, and then 134 mg (0.65 mmol) of dicyclohexylcarbodiimide was added.
The reaction was allowed to proceed at room temperature for 15 hours.

After completion of the reaction, the precipitated solid was filtered out, washed with water, washed with a 5% aqueous acetic acid solution, washed with water, and then dried over anhydrous magnesium sulfate. After filtering off the desiccant, methylene chloride was distilled off to obtain a crude target product.

This product was purified by silica gel chromatography and further recrystallized from hexane to obtain the desired (R)-5-(4-dodecyloxyphenyl)-
2-pyrazinecarboxylic acid-4-(1-trifluoromethylheptyloxycarbonyl)phenyl ester 240
mg (0.35 mmol) was obtained.

1H-NMR spectrum (CDCl3,p
pm) 0.86 (t, 3H), 0.88 (t, 3H), 1.2
7-1.51 (m, 26H), 1.81-1.90 (m
, 4H), 4.06 (t, 2H), 5.55 (m, 1H
), 7.07 (d, 2H), 7.42 (d, 2H), 8
．． 12 (d, 2H), 8.20 (d, 2H), 9.16
(s, 1H), 9.42 (s, 2H)

IR
Spectrum (KBr disk, cm-1) 2870, 2800, 1740, 1590, 1250,
1200,830,790

Mass spectrum (EI method, m/e (relative intensity)) 670 (9, M+), 367 (100)

Phase transition temperature (DSC, polarized light microscopy observation, °C)

[Chemical formula 8]

[0083]

[Example 2] After coating polyimide on two glass substrates provided with transparent electrodes, the glass substrates were assembled so that their rubbing directions were parallel to each other.
The compound obtained in Example 1 was injected into a .mu.m cell and sandwiched between two polarizing plates arranged perpendicularly to each other to produce a liquid crystal element.

[0084] When the optical response speed was measured by applying a voltage of ±60 V at 70° C., a very fast response time of 35 μsec was obtained.

Claims (2)

[Claims] 1. An optically active pyrazine compound represented by the following formula 1 (hereinafter, this formula is referred to as "general formula (1)" in the present specification). embedded image [However, R1 in the above general formula (1) represents an alkyl group or an alkoxy group having 4 to 16 carbon atoms, and R2 is
It represents an alkyl group having 4 to 12 carbon atoms, and * represents optical activity. ] 2. A display element characterized by using an optically active pyrazine compound represented by the following general formula (1). embedded image [However, R1 in the above general formula (1) represents an alkyl group or an alkoxy group having 4 to 16 carbon atoms, and R2 is
It represents an alkyl group having 4 to 12 carbon atoms, and * represents optical activity. ]