JP2989317B2 - Liquid crystal compositions containing novel phenylpyridine compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can take a stable thermotropic liquid crystal state, for example, for a display such as a liquid crystal television, an optical printer head, an optical Fourier transform element,
The present invention relates to a liquid crystal composition to which a novel phenylpyridine compound is added, which can be used as a liquid crystal material useful as a material for an optoelectronics device utilizing liquid crystal or electrochemiomics, such as a light valve.

[0002]

2. Description of the Related Art At present, liquid crystal compounds are applied to various devices as display materials and have been put to practical use in watches, calculators, small televisions and the like. These use a cell having a nematic liquid crystal material as a main component, and adopt a display type called a TN type or STN type. Cell in this case is actuated based on a weak interaction between the dielectric anisotropy Δε and the electric field E of the liquid crystal compound (ΔεE ^2/2), the response speed to the electric field is low and the number m sec can be mentioned as a disadvantage ing. Therefore, when used in a television, an active matrix system in which switching elements are arranged and added for each pixel is mainly used as a driving system, which is one of the obstacles in achieving a large screen.

However, 4- (4-n-decyloxybenzylideneamino) cinnamic acid-2-methylbutyl ester (DOBAMBC) synthesized by RB Meyer et al. In 1975.
And the appearance of ferroelectric liquid crystals, and N.
A new display method proposed by A. Clark et al. (Applied Phys.
Lett. 1980, 36 , 899) has made possible a liquid crystal cell having a high-speed response on the order of μsec and a characteristic (memory property) in which the orientation of liquid crystal molecules does not change even when the electric field is cut off.
The use of display elements made of these materials makes it possible to use a multiplex drive without the use of switching elements, etc., to enable a simple matrix LCD TV, and to increase productivity, cost, reliability, and a larger screen compared to active matrix displays. It will be much more advantageous in such aspects.

[0004] Each of the above-mentioned display cells utilizes the optical switching phenomenon of a chiral smectic C phase (hereinafter referred to as Sc ^* phase). As a liquid crystal material exhibiting such a Sc ^* phase, a smectic C phase (hereinafter referred to as Sc ^* phase) is used. (Sc phase)
A chiral smectic mixed liquid crystal of a type prepared by adding a ferroelectric chiral compound to a mixed liquid crystal showing the following is effective.

[0005]

In order to ensure a wide operating temperature range for this type of display cell, the chiral smectic mixed liquid crystal used must be capable of exhibiting the Sc ^* phase over a wide temperature range. In order to prepare a chiral smectic mixed liquid crystal exhibiting the Sc ^* phase in such a wide temperature range, a smectic mixed liquid crystal to which a ferroelectric chiral compound should be added should be one exhibiting an Sc phase in a wide temperature range. Is effective.

As a method for preparing a smectic mixed liquid crystal exhibiting the Sc phase in a wide temperature range, generally, a smectic liquid crystal exhibiting the Sc phase in a low temperature range and a smectic liquid crystal exhibiting the Sc phase in a high temperature range are mixed. And a method of preparing it. Therefore, the following 3
It is desired to use various smectic liquid crystal compounds satisfying the following conditions. (1) It shows Sc phase in a wide temperature range. (2) It does not show a smectic phase higher than the Sc phase. (3) When mixed with a smectic mixed liquid crystal exhibiting an Sc phase, a melting point lowering effect is exhibited. Further, by mixing with a mixed liquid crystal showing an Sc phase,
It is also desired to use various smectic liquid crystal compounds capable of extending the Sc phase temperature range of the composition.

Accordingly, an object of the present invention is to provide a novel liquid crystal compound exhibiting an Sc phase, and to add and mix this compound to a smectic mixed liquid crystal exhibiting an Sc phase to thereby control the temperature range of the Sc phase of the composition. It is an object of the present invention to provide a novel liquid crystal composition which is enlarged.

[0008]

Means for Solving the Problems The present inventors have found that a phenylpyridine compound having a specific structure can take a thermotropically stable liquid crystal state, and that the compound can be used as another S-phenylpyridine compound.
The present inventors have found that when mixed with a liquid crystal exhibiting the c phase, they exhibit the Sc phase in a wide temperature range, and have completed the present invention.

That is, the present invention provides a compound represented by the general formula (I):

Embedded image (Wherein R and R 'each represent an alkyl group having 1 to 18 carbon atoms). The present invention relates to a liquid crystal composition obtained by adding and mixing a phenylpyridine compound represented by the following formula: Specifically, an achiral smectic compound (5-alkyl-2- (4-alkoxyphenyl) represented by a liquid crystal mixture A described later is used as a liquid crystal mixture showing an Sc phase.
A liquid crystal mixture containing (pyrimidine) as a main component is used.

The following are examples of typical compounds of the above formula (I) and their physicochemical properties. 5-octyloxy-2- (4-octyloxyphenyl
G ) Pyridine ¹ H-NMR (90 MHz, TMS standard, δ value) δ 0.88 6Hm δ 1.0 to 2.024Hm δ 4.012Ht (J = 7 Hz) δ 4.03 2Ht (J = 7 Hz) δ 6.97 2Hd (J = 9 Hz) δ 7.24 1H dd (J = 9 Hz, 1.5H
z) δ 7.60 1H d (J = 9 Hz) δ 7.87 2H d (J = 9 Hz) δ 8.36 1H d (J = 1.5 Hz) IR (KBr method, cm ⁻¹ ) 2910, 2840, 1602, 1465, 1255 , 812

[0011] 5-heptyloxy-2- (4-octyl)
(Oxyphenyl ) pyridine ¹ H-NMR (90 MHz, TMS standard, δ value) δ 0.88 6H m δ 1.0 to 2.022H m δ 4.012 Ht (J = 7 Hz) δ 4.032Ht (J = 7 Hz) δ 6.97 2H d (J = 9 Hz) δ 7.23 1H dd (J = 9 Hz, 1.5 H
z) δ 7.60 1H d (J = 9 Hz) δ 7.87 2H d (J = 9 Hz) δ 8.37 1H d (J = 1.5 Hz) IR (KBr method, cm ⁻¹ ) 2910, 2840, 1602, 1465, 1255 , 812

The compound of the above formula (I) can be obtained as follows.

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That is, it is obtained by alkylating 5-hydroxy-2- (4-alkyloxyphenyl) pyridine. As an alkylation method, it is convenient to react with an alkyl halide under basic conditions.

[0014] The 5-hydroxy-2-
(4-Alkyloxyphenyl) pyridine can be obtained according to the following formula.

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That is, after alkylating the phenolic hydroxyl group of 4-bromophenol, it is metallized and reacted with 2,5-dibromopyridine in the presence of a Pd catalyst to form a phenylpyridine derivative, and the remaining Br is metallized. To a boric acid derivative through oxidation with hydrogen peroxide.
-Hydroxy-2- (4-alkyloxyphenyl) pyridine is obtained.

[0016]

Next, the present invention will be described in detail with reference to examples. Example 1 5-octyloxy-2- (4-octyloxyphenyl
G ) Pyridine synthesis 15.70 g of 4-octyloxybromobenzene (55.1 mmo
l) was dissolved in 300 ml of dry tetrahydrofuran under a nitrogen atmosphere and cooled to -78 ° C. To this, 34.0 ml (55.1 mmol) of a 1.62 M n-butyllithium hexane solution was added dropwise,
The mixture was stirred for 3 hours. Thereafter, 8 ml of trimethyl borate was added thereto, and the temperature was raised to room temperature. After adding 1N hydrochloric acid, the mixture was extracted with ether and washed with a saturated aqueous sodium chloride solution. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and the resulting oil was dissolved in 60 ml of ethanol, and 11.65 g (50.0 mmol) of 2,5-dibromopyridine dissolved in 150 ml of toluene and tetrakistriphenyl were dissolved in 150 ml of toluene. 0.47 g of phosphine palladium (0) and 70 ml of a 2N aqueous sodium hydrogen carbonate solution were added, and the mixture was heated under reflux for 5 hours. After cooling, the resulting two phases were separated, and the aqueous phase was extracted with ether.
The organic phase was combined with this and washed with distilled water. Next, after drying over anhydrous magnesium sulfate, the solvent was distilled off, and the obtained oil was purified by silica gel column chromatography and a recrystallization method from ethanol to obtain white crystals.
13.51 g (75% yield) of-(4-octyloxyphenyl) -5-bromopyridine was obtained.

Under a nitrogen atmosphere, 5.00 g (13.8 mmol) of the obtained 2- (4-octyloxyphenyl) -5-bromopyridine was dissolved in 130 ml of dry tetrahydrofuran.
Cooled to ° C. To this, 9.5 ml (15.4 mmol) of a 1.62 M hexane solution of n-butyllithium was added dropwise, and the mixture was stirred for 3 hours. Further, 2 ml of trimethyl borate was added thereto, and the temperature was gradually raised to room temperature. After adding distilled water, extraction was performed with tetrahydrofuran. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and the resulting oil was dissolved in 70 ml of acetic acid, 15 ml of a 36% aqueous hydrogen peroxide solution was added, and the mixture was stirred at room temperature overnight. Then, 300 ml of distilled water was added thereto, extracted with dichloromethane, and washed with distilled water and then with a saturated aqueous solution of sodium chloride. After drying over anhydrous magnesium sulfate, the solvent was distilled off and the resulting oil was purified by silica gel column chromatography and recrystallization from ethanol to give white crystals of 5-hydroxy-2- (4-octyloxyphenyl). 2.46 g (60% yield) of pyridine were obtained.

1.00 g (3.3 mmol) of the obtained 5-hydroxy-2- (4-octyloxyphenyl) pyridine, 1
-1 ml of iodooctane, 1.07 g of anhydrous potassium carbonate (7.75 m
mol) and 10 ml of dry dimethyl sulfoxide were placed in a flask and stirred at room temperature for 2 nights. 100 ml of distilled water was added thereto, extracted with ether, and washed with distilled water. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and the crude crystals obtained were purified by silica gel column chromatography and recrystallization from ethanol to give 5-octyloxy-2, a white crystal having the above-mentioned physicochemical properties. 1.23 g (89% yield) of-(4-octyloxyphenyl) pyridine was obtained.

Evaluation of Liquid Crystallinity The compound obtained as described above was injected into a 3 μm-thick cell made of a glass plate with a transparent electrode coated with polyimide and subjected to a rubbing treatment, at a rate of -2 ° C./min. When observed with a crossed Nicol polarizing microscope while lowering the temperature at
At 8 ° C., the phase changed from an isotropic liquid to a Sc phase. When the temperature was further lowered, it crystallized at 74 ° C. When the temperature was raised, the crystal changed from the crystal to the Sc phase at 75 ° C.

Example 2 5-heptyloxy-2- (4-octyloxyphenyl
L) Pyridine synthesis 1.00 g (3.3 mmol) of 5-hydroxy-2- (4-octyloxyphenyl) pyridine obtained in Example 1, 1-
1 ml of iodoheptane, 0.97 g of anhydrous potassium carbonate (7.03 mmo
l) and 10 ml of dry dimethyl sulfoxide were placed in a flask and stirred at room temperature for 2 nights. Add 100 ml of distilled water to this,
Extracted with ether and washed with distilled water. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and the crude crystals obtained were purified by silica gel column chromatography and recrystallization from ethanol to give 5-heptyloxy-white crystals having the above physicochemical properties. 1.19 g of 2- (4-octyloxyphenyl) pyridine was obtained (89% yield).

Evaluation of Liquid Crystallinity The compound obtained as described above was injected into a 3 μm-thick cell made of a glass plate with a transparent electrode coated with polyimide and subjected to rubbing treatment, at a rate of -2 ° C./min. When observed with a crossed Nicol polarizing microscope while lowering the temperature at
At 4 ° C., the phase changed from an isotropic liquid to a Sc phase. When the temperature was further lowered, it crystallized at 82 ° C. When the temperature was raised, the crystal changed from the crystal to the Sc phase at 84 ° C. Example 3 Preparation of Liquid Crystal Composition A liquid crystal compound (1) exhibiting an Sc phase represented by each of the following formulas,
Liquid crystal mixture A was prepared by mixing (2), (3) and (4) in the proportions shown below.

Embedded image

This liquid crystal composition A exhibited the following phase transition behavior. 2 ° C 47 ° C 62 ° C 67 ° C Cr ← Sc ← S _A ← N ← I (Cr indicates a crystal phase, S _A indicates a smectic A phase, N indicates a nematic phase, and I indicates an isotropic phase.)

This liquid crystal composition A and the compound of Example 1 were mixed at the following ratio to prepare a liquid crystal composition B.

Embedded image

This liquid crystal composition B exhibited the following phase transition behavior. Thus, as compared with the liquid crystal composition A, the melting point decreased by 4 ° C., and the upper limit temperature of the Sc phase also increased by 10 ° C. Thereby, a wide Sc phase temperature range could be obtained.

[0025]

According to the present invention, there is provided a liquid crystal composition obtained by adding and mixing at least one compound showing a stable Sc phase of the general formula (I) with another base liquid crystal as a main component. It is extremely effective as a material for optoelectronics-related elements, such as extending the temperature range of the liquid crystal Sc phase. Thus, the present invention, for example,
It can be said that it is a useful liquid crystal material as a material for optoelectronics-related devices utilizing liquid crystal and electrochemiomics, such as liquid crystal televisions and other displays, optical printer heads, optical Fourier transform elements, and light valves.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07D 213/00-213/65 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. An achiral smectic compound exhibiting an Sc phase: a liquid crystal mixture containing 5-alkyl-2- (4-alkoxyphenyl) pyrimidine as a main component and exhibiting an Sc phase has the following general formula (I): ] (Wherein, R and R ′ each represent an alkyl group having 1 to 18 carbon atoms). A liquid crystal composition obtained by adding and mixing at least one novel phenylpyridine compound represented by the formula: