JP2764596B2 - Chlorine-containing optically active biphenyl compounds - Google Patents

Description

The present invention relates to an optically active chlorine-containing biphenyl compound,
More specifically, the present invention relates to a chlorine-containing optically active biphenyl compound, which is a liquid crystal compound that is useful as an electro-optical device and utilizes a response of a ferroelectric smectic liquid crystal to an electric field.

[Conventional technology and its problems]

Liquid crystals have been applied as various electro-optical elements and have been put to practical use in displays of watches, calculators and the like. Most of the liquid crystal display elements that are currently most practically used utilize a dielectric alignment effect of a twisted nematic liquid crystal or a cholesteric liquid crystal. However, in application to a display element having a large number of pixels, which is expected, there are problems in terms of responsiveness, contrast and viewing angle characteristics due to lack of a drive margin. For this reason, research and development of MOS panels and TFT panels that form a switching element for each pixel have been actively conducted.

U.S. Pat. No. 4,367,924 discloses a liquid crystal device based on a new display principle using a smectic phase that eliminates such a defect of the liquid crystal device.

In addition, a liquid crystal compound exhibiting a smectic C ^* phase or an H phase composed of optically active molecules generally has an electric dipole density P and is known to be ferroelectric. Since these chiral smectic liquid crystals have an electric dipole, they are more strongly affected by an electric field than by dielectric anisotropy.
Since this acting force has the property that the polarity of P is in the direction parallel to the electric field, the direction of the molecule can be controlled by reversing the direction of the applied electric field. Then, by detecting the average change of the molecule in the major axis direction using two polarizing plates, it can be used as an electro-optical element.

The electro-optical element utilizing the response to the electric field of the stochastic C ^* phase or the H phase has a spontaneous polarization and an action force exerted by the electric field three to four orders of magnitude larger than those due to the dielectric anisotropy. It has a high-speed response superior to that of, and can have a memory function by performing appropriate orientation control, and is expected to be applied to high-speed optical shutters or displays with a large amount of display information. It is.

As for such a chiral smectic liquid crystal material having ferroelectricity, various compounds have been synthesized and their properties have been studied.

Based on this idea, for example, it has been proposed to use an optically active 2-methylbutyl-p- (pn-decyloxybenzylideneamino) cinnamate (DOBAMBC) compound as a component of a ferroelectric liquid crystal composition. Was. However, this compound has a high temperature at which the compound exhibits liquid crystallinity of 60 ° C. or higher, so that it has been subject to temperature restrictions when used.

There has been a demand for a crystal composition which exhibits ferroelectricity over a wide temperature range around room temperature and has a short response time.

[Means for solving the problem]

In view of the above-mentioned development, the present inventors have conducted intensive studies to find an optically active compound in which the liquid crystal composition for a display element can be used in an appropriate temperature range. As a result, the liquid crystal composition is represented by the following general formula (I). It has been found that a novel chlorine-containing optically active biphenyl compound is a very suitable compound to be used for the above purpose.

(Wherein, R ₁ and R ₂ each independently represent 1 to 18 carbon atoms)
Alkyl group or group of R ₃ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, m represents 2 to 5, n represents 1 to 3, *
Represents an asymmetric carbon atom. However, at least one of R ₁ and R ₂ represents the above-mentioned optically active group. The chlorine-containing optically active biphenyl compound represented by the general formula (I) will be described in more detail.

As the alkyl group having 1 to 18 carbon atoms represented by R,
Methyl, methyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, lauryl,
Myristyl, palmityl, stearyl and the like.

Since the compound of the present invention has an optically active group, it can be used as one component of a ferroelectric liquid crystal composition.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited by the following examples.

Example 1 Synthesis of (R) -4 '-(6 "-chloro-4" -methyloctyloxy) -4-biphenylcarboxylic acid methyl ester Methyl 4'-hydroxy-4-biphenylcarboxylate
0.96 g, (R) -6-chloro-4-methyloctanol
0.70 g, triphenylphosphine 1.21 g and ethyl azodicarboxylate 0.80 g were dissolved in 10 ml of ethyl ether and stirred at room temperature for 3 hours.

After filtering off the precipitated triphenylphosphine oxide,
The filtrate was desolvated. After removing the solvent, the residue was purified with a silica gel column using n-hexane / ethyl acetate (93/7) as a developing solvent to give (R) -4 '-(6 "-chloro-4" -methyloctyloxy) -4-biphenyl. 1.07 g of a white solid of carboxylic acid methyl ester was obtained.

Mp ^{102.8~103.3 ℃ IR: 2925cm -1 (s} ), 1715cm -1 (s), 1600cm -1 (m),
1525cm ^-1 (w), 1495cm ^-1 (w), 1455cm ^-1 (w), 14
30cm ^-1 (w), 1395cm ^-1 (w), 1285cm ^-1 (s), 1200
^{cm -1 (m), 1110cm -1} (m), 1030cm -1 (w) 825cm -1
(M), 770 cm ^-1 (m) Example 2 Synthesis of (R) -4 '-(6 "-chloro-4" -methyloctyloxy) -4-biphenylcarboxylic acid decyl ester The biphenylcarboxylic acid methyl ester obtained in Example 1 was saponified with potassium hydroxide / ethyl alcohol aqueous solution, and then neutralized with 10% hydrochloric acid to give (R) -4'-.
(6 "-chloro-4" -methyloctyloxy) -4-
Biphenylcarboxylic acid was obtained. This biphenylcarboxylic acid (0.40 g), decyl alcohol (0.19 g), diethyl azodicarboxylate (0.22 g) and triphenylphosphine (0.34 g) were dissolved in ethyl ether (5 ml) and stirred at room temperature for 3 hours. After the same treatment as in Example 1, n-hexane / ethyl acetate (95/5) was eluted and purified by a silica gel column to give (R) -4 '-(6 "-chloro-4"-). 0.31 g of a colorless liquid of methyl octyloxy) -4-biphenylcarboxylate decyl ester was obtained.

^{IR: 2925cm -1 (s),} 1715cm -1 (s), 1605cm -1 (m),
^{1525cm -1 (w), 1495cm -1} (w), 1460cm -1 (w), 13
^{80cm -1 (w), 1275cm -1} (s), 1245cm -1 (m), 1190
^{cm -1 (m), 1110cm -1} (m), 1030cm -1 (w), 830cm
^-1 (m), 775 cm ^-1 (m) The compound was sandwiched between two glass plates, and the phase morphology was observed with a polarizing microscope. As a result, the following phase transition was confirmed.

Example 3 Synthesis of octyl (R) -4 '-(6 "-chloro-3" -methylhexyloxy) -4-biphenylcarboxylate (R) -4 '-(6 "-chloro-3" -methylhexyloxy) biphenylcarboxylic acid 0.30 g, octanol
0.20 g, diethyl azodicarboxylate 0.21 g and triphenylphosphine 0.31 g were dissolved in ethyl ether 5 ml,
Stirred at room temperature for 2 hours. After performing the same treatment as in Example 1, silica gel column purification was performed using n-hexane / ethyl acetate (93/7) as a developing solvent, and (R) -4 '-(6 "-) was purified.
There was obtained 0.27 g of a colorless liquid of octyl chloro-3 ″ -methylhexyloxy) biphenylcarboxylate.

^{IR: 2940cm -1 (s),} 1715cm -1 (s), 1605cm -1 (m),
^{1525cm -1 (w), 1500cm -1} (w), 1470cm -1 (w), 13
^{85cm -1 (w), 1275cm -1} (s), 1250cm -1 (m), 1190
^{cm -1 (m), 1115cm -1} (m), 1030cm -1 (w), 830cm
^-1 (m), 775 cm ^-1 (m) The compound was sandwiched between two glass plates, and the phase morphology was observed with a polarizing microscope. As a result, the following phase transition was confirmed.

Example 4 Synthesis of (R) -4'octyloxy-4-biphenylcarboxylic acid-6-chloro-4-methylnonyl ester.

4'-octyloxy-4-biphenylcarboxylic acid
33 g, (R) -6-chloro-4-methylnonyl alcohol 0.12 g, diethyl azodicarboxylate 0.21 g and triphenylphosphine 0.31 g were dissolved in ethyl ether 5 ml and stirred at room temperature for 3 hours. After performing the same treatment as in Example 1, silica gel column purification was performed using n-hexyl / ethyl ether (95/5) as a developing solvent to give (R) -4'octyloxy-4-biphenylcarboxylic acid-6-chloroform. 0.25 g of a white solid of -4-methylnonyl ester was obtained.

IR: 2950cm ^-1 (s), 1715cm ^-1 (s), 1610cm ^-1 (m),
^{1530cm -1 (w), 1500cm -1} (w), 1470cm -1 (w), 13
^{85cm -1 (w), 1275cm -1} (s), 1250cm -1 (m), 1195
^{cm -1 (m), 1115cm -1} (m), 1040cm -1 (w), 835cm
^-1 (m), 780 cm ^-1 (m) This compound was sandwiched between two glass plates, and phase morphology was observed with a polarizing microscope. As a result, the following phase transition was confirmed.

Reference Example Four kinds of compounds represented by the following general formulas were mixed to prepare a mother liquid crystal composition.

This mother liquid crystal composition gives the following phase transition.

A liquid crystal composition obtained by adding 10 parts of each of the compounds of the present invention synthesized in Examples 2 and 4 to 90 parts of the mother liquid crystal composition has the following physical properties.

The above liquid crystal composition was coated with polyimide as an alignment film, and the surface was rubbed and injected into a 2 μm-thick cell having a glass transparent electrode subjected to a parallel alignment treatment by rubbing to form a liquid crystal display element. When the response speed (Ps) at 20 ° C. when a 15 V electric field (60 Hz rectangular wave alternating current) was applied and the spontaneous polarization (τ) were measured using the triangular wave method, the following values were obtained.

As apparent from the above results [Effect of the Invention, by adding a small amount of chlorine-containing optically active biphenyl compound according to the present invention, to impart a spontaneous polarization to the mother liquid crystals of SmC ^* phase having SmC ^* phase, chiral smectic It can be C phase.

Therefore, the chlorine-containing optically active biphenyl compound according to the present invention is useful for use as one component of a ferroelectric liquid crystal composition.

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Claims (1)

(57) [Claims] 1. A chlorine-containing optically active biphenyl compound represented by the following general formula (I). (Wherein, R ₁ and R ₂ each independently represent 1 to 18 carbon atoms)
Alkyl group or group of R ₃ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, m represents 2 to 5, n represents 1 to 3, *
Represents an asymmetric carbon atom. However, at least one of R ₁ and R ₂ represents the above-mentioned optically active group. )