JP2691754B2 - Optically active alkoxy phenyl pyrimidine compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a specific optically active alkoxyphenylpyrimidine compound, and more specifically, it is useful as an electro-optical element utilizing the response of a ferroelectric smectic liquid crystal to an electric field. And an optically active alkoxyphenylpyrimidine compound, which is a novel liquid crystal compound.

[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, smectic C ^* consisting of optically active molecules
A liquid crystal compound exhibiting a phase or an H phase generally has an electric dipole density P and is known to be ferroelectric. Since these chiral smectic liquid crystals have electric dipoles, they are more strongly affected by the electric field than by the dielectric anisotropy, and this acting force has the property that the polarity of P points 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 smectic C ^* phase or the H phase has a spontaneous polarization and an acting 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.

For example, Japanese Patent Application Laid-Open No. 61-215373 discloses an optically active alkoxyphenyl-alkylphenylpyrimidine compound, and the 13th Liquid Crystal Symposium Proceedings, pp. 46-47 (Showa 6).
In 2), an optically active alkoxyphenyl-alkyl or alkoxyphenyl-pyrimidine compound is proposed as a compound exhibiting a chiral smectic phase in a high temperature range over a wide temperature range.

However, in these compounds, since the optically active alkoxy group is derived from 2-methylbutanol, the alkyl group bonded to the asymmetric carbon atom is limited to an ethyl group. These compounds are not suitable for use as one component of a ferroelectric liquid crystal composition used near room temperature because the temperature at which a chiral smectic phase is exhibited is too high. In addition, these compounds have small spontaneous polarization and are not satisfactory in practical use.

[Means for solving the problem]

In view of the above situation, the inventors of the present invention have made earnest studies to find an optically active compound in which the usable temperature range of the liquid crystal composition for a display device is appropriate, and the result is represented by the following general formula (I). It has been found that the novel optically active alkoxyphenylpyrimidine compound described above is a very suitable compound for use for the above purpose.

(In the formula, R represents a linear alkyl group having 1 to 18 carbon atoms, R'represents a hydrogen atom or an alkyl group having 1 to 11 carbon atoms, and * represents an asymmetric carbon atom.) The optically active alkoxyphenylpyrimidine compound represented by the formula (I) will be described in more detail.

Examples of the linear alkyl group having 1 to 18 carbon atoms represented by R include methyl, ethyl, propyl, butyl, pentyl,
Hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, hexadecyl, octadecyl groups and the like can be mentioned.

Examples of the alkyl group having 1 to 11 carbon atoms represented by R ′ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,
An undecyl group etc. are mentioned.

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,
A compound in which R is an alkyl group having about 6 to 18 carbon atoms can be used as a liquid crystal having ferroelectricity.

Further, the compound of the present invention is one in which the alkyl group bonded to the asymmetric carbon atom of the optically active alkoxy group has a chlorine atom and the corresponding optically active alkoxy group having an ethyl group as the alkyl group bonded to the asymmetric carbon atom. Compared with a pyrimidine compound having an alkoxy group, it has a characteristic that the temperature of exhibiting a chiral smectic phase is about 10 to 20 ° C. lower, and it is particularly used as a component of a ferroelectric liquid crystal composition used near room temperature. It is suitable for.

〔Example〕

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 (4 ", R) -2- [4 '-(6" -chloro-4 "-methyloctyloxy) phenyl] -5-octyloxypyrimidine.

6-chloro-4-methyl-1-octanol ([α]
= + 0.75, 28 ° C, 1.32% chloroform] 0.14g, 2-
0.24 g of (4-hydroxyphenyl) -5-octyloxypyrimidine, 0.22 g of triphenylphosphine and 0.15 g of diethyl azodicarboxylate were dissolved in 10 ml of ethyl ether and stirred at room temperature for 3 hours. After the precipitated triphenylphosphine oxide was filtered off, the filtrate was desolvated. The desolvation residue was added to n-hexane / ethyl ether (75/1
After purification with a silica gel column using 5) as a developing solvent,
Further, it was recrystallized from acetone / ethyl alcohol to obtain the desired (4 ″, R) -2- [4 ′-(6 ″ -chloro-4 ″ -methyloctyloxy) phenyl] -5-octyloxypyrimidine.

As a result of an infrared spectroscopic analysis, the obtained product had the following characteristic absorption and was confirmed to be the desired product.

^{2925cm -1 (s), 1605cm -1} (m), 1580cm -1 (w), 1550cm -1 (w), 1510cm -1 (w), 1440cm -1 (vs), 1390cm -1 (w), 1285cm ^-1 (s), 1250cm ^-1 (s), 1170cm ^-1 (w), 790cm ^-1 (w) This compound was sandwiched between two glass plates and the phase morphology was observed with a polarizing microscope. Was confirmed.

This compound was applied to polyimide as an aligning agent, and the surface was rubbed to be injected into a 2 μm-thick cell equipped with a glass transparent electrode that was subjected to parallel alignment treatment. When a square wave alternating current) was applied, a clear change in transmitted light intensity was observed. The response speed (time from application of the electric field to 90% rise) at that time was 310 μsec. The spontaneous polarization by the triangular wave method was 37.4 nC / cm ² (40 ° C).

〔The invention's effect〕

As exemplified above, the optically active alkoxyphenylpyridimine compound of the present invention is advantageous for use as a component of a ferroelectric liquid crystal composition used near room temperature, and spontaneous polarization also has a great feature. doing.

Claims (1)

(57) [Claims] 1. An optically active alkoxyphenylpyrimidine compound represented by the following general formula (I). (In the formula, R represents a linear alkyl group having 1 to 18 carbon atoms, R'represents a hydrogen atom or an alkyl group having 1 to 11 carbon atoms, and * represents an asymmetric carbon atom.)