JP2510664B2 - Liquid crystalline compound, liquid crystal composition containing the same, and liquid crystal device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal compound, a liquid crystal composition containing the same, and a liquid crystal device.

[Background technology]

As a conventional liquid crystal element, for example, M.Chat (M.
Schadt and W. Helfrich, “Applied Physics Redders” (“Applied
Physics Letters ") Volume 18, Issue 4 (Published February 15, 1971), pages 127-128," Voltage Day Pendant Optical Activity of a Twisted Nematic Stick Liquid Crystal ""(" Volt
age Dependent Optical Activity of a Twisted Nemati
c Liquid Crystal ") is known to use twisted nematic liquid crystal. This TN liquid crystal is a cross-type liquid crystal that is driven by a time division drive using a matrix electrode structure with high pixel density. The number of pixels is limited because of the problem of generating talk.

Further, since the electric field response is slow and the viewing angle characteristic is poor, the use as a display is limited.

Further, there is known a display element in which a switching element formed by a thin film transistor is connected to each pixel, and each pixel is switched.However, a process of forming a thin film transistor on a substrate is extremely complicated, and a large area display element is used. There are problems that are difficult to create.

The use of bistability-type liquid crystal elements is known as Clark (Cl
ark) and Lagerwall (JP-A-56-107216, U.S. Pat. No. 4,367,924, etc.), a liquid crystal having bistability is generally a chiral smectic C phase ( SmC ^* ) or H phase (SmH ^* )
A ferroelectric liquid crystal having is used.

This ferroelectric liquid crystal has a very fast response speed due to its spontaneous polarization, and can express a bistable state with a memory property. Moreover, it has a large viewing angle characteristic and thus has a large capacity and a large capacity. Suitable as a display material for screens.

Since the material used as the ferroelectric liquid crystal has asymmetry, it should be used not only as the ferroelectric liquid crystal utilizing its chiral smectic phase but also as the following optical element. You can

1) Utilizing the cholesteric / nematic phase transition effect in the liquid crystal state (JJWysoki, A. Adams and WH
aas; Phys.Rev.Lett., 20,1024 (1968)), 2) Utilizing the white Taylor type guest-host effect in the liquid crystal state (DLWhite and GNTaylor;
J. Appl. Phys., 45 , 4718 (1974)).
Although detailed description of each method is omitted, it is important as a display element or a modulation element.

In such a method using the electric field response optical effect of the liquid crystal, it is considered preferable to introduce a polar group in order to enhance the response of the liquid crystal. In particular, it is known that the response speed of a ferroelectric liquid crystal is proportional to the spontaneous polarization, and it is desired to increase the spontaneous polarization for speeding up. From these points, P. Keller and colleagues showed that direct introduction of a chlorine group on the asymmetric carbon could increase spontaneous polarization and increase the response speed (CRAcad.Sc.Pa).
ris, 282 C, 639 (1976)). However, the chlorine group introduced into the asymmetric carbon is chemically unstable and has a drawback that the stability of the liquid crystal phase is deteriorated due to its large atomic radius, and improvement thereof is desired. There is.

On the other hand, a functional material required for an optical element characterized by having optical activity is often synthesized through an optically active intermediate itself, but as an optically active intermediate used conventionally, 2 -Methylbutanol, secondary octyl alcohol, secondary butyl alcohol, p- (2-methylbutyl) benzoic acid chloride, secondary phenethyl alcohol, amino acid derivatives, camphor derivatives, cholesterol derivatives, etc. Almost no polar group was introduced into the intermediate. For this reason also, by directly introducing a polar group into the asymmetric carbon atom,
The method of increasing spontaneous polarization has not been used very effectively.

[Object of the Invention]

The present invention has been made in view of the above points. That is, the present invention directly introduces into the asymmetric carbon atom a stable trifluoromethyl group having a large dipole moment to thereby increase the polarity, and a liquid crystal compound containing at least one kind of the liquid crystal compound, It is an object to provide a liquid crystal composition having improved electric field response.

[Outline of Invention]

The present invention has been made to achieve the above object, and a liquid crystal compound represented by the general formula (I), (Here, R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkyl group having 1 to 12 carbon atoms, X is a single bond, —O
-, Or Y is --CH ₂ O--, or --OCH _2- , Z is --OC
H ₂ CH ₂ − or Is either.

C ^* is an asymmetric carbon atom. Note that k, m,
n is independently selected from 0, 1, 2 and k + m +
n is a number that becomes 2 or 3. ) And a liquid crystal composition containing at least one thereof. The present invention also provides a liquid crystal device using such a liquid crystal composition.

[Specific Description of the Invention]

The liquid crystal compound represented by the above general formula is preferably applied by the present applicant (Japanese Patent Application No. 62-183485 and 1988 2).
The following general formula (2) shown in the specifications of the applications filed on March 22,
Is produced from an optically active intermediate such as optically active 3-trifluoromethyl-1-heptanoic acid or 3-trifluoromethyl-1-heptanol. The main production methods are shown below.

Where R ₁ , R ₂ , X, Z, k, m, n and C ^* are as defined above.

The compounds that can be produced as described above are listed below.

The liquid crystal composition of the present invention contains at least one trifluoroalkane derivative represented by the general formula (I) as a blending component. For example, when this trifluoroalkane derivative is combined with a ferroelectric liquid crystal represented by the following formulas (1) to (13), spontaneous polarization is increased and the response speed can be improved.

In such a case, the trifluoroalkane derivative of the present invention represented by the general formula (1) may be used in an amount of 0.1 to 99% by weight, particularly 1 to 90% by weight of the obtained liquid crystal composition. preferable.

Further, by blending with a smectic liquid crystal which is not chiral as shown by the following formulas 1) to 5),
A composition that can be used as a ferroelectric liquid crystal is obtained.

In this case, the trifluoroalkane derivative of the present invention represented by the general formula (1) is added in an amount of 0.1 to 99 of the liquid crystal composition obtained.
It is preferred to use it in an amount of 1% to 90% by weight.

Such a composition can obtain a large spontaneous polarization due to the content of the trifluoroalkane derivative of the present invention.

Here, the symbols indicate the following phases, respectively.

Cryst .: Crystal phase, SmA: Smectic A
Phase, SmB: smectic B phase, SmC: smectic C
Phase, N: nematic phase, Iso .: isotropic phase, the present invention will be described in more detail with reference to the following examples.

Example 1. Preparation of 4-octyl-4 '-[4 "-(3-tolufluoromethylheptyloxy) benzyloxy] biphenyl 4-octyl-4'[4"-(3
-Trifluoromethylheptyloxy) benzyloxy] biphenyl was prepared.

Step 1) Production of (+)-p-toluenesulfonic acid 3-trifluoromethylheptyl ester (-)-3-trifluoromethyl- in an eggplant-shaped flask.
While adding 3.3 g of 1-heptanol and 5.7 g of pyridine and stirring, add 3.4 g of p-toluenesulfonic acid chloride 15
The reaction was performed at 2020 ° C. for 4 hours. The reaction solution was poured into water, hydrochloric acid was added, the mixture was extracted with diethyl ether, dried over sodium sulfate, the solvent was distilled off, and 5.3 g of (+)-p-
Toluenesulfonic acid and 3-trifluoromethylheptyl ester were obtained.

Step 2) Production of (+)-p- (3-trifluoromethylheptyloxy) benzyl alcohol p-dissolved in 10 ml of ethanol in an eggplant type flask.
2.4 g of hydroxybenzyl alcohol and 5.3 g of (+)-p-toluenesulfonic acid 3-trifluoromethylheptyl ester were added, and a solution of 0.8 g of sodium hydroxide in 10 ml of ethanol was added dropwise thereto and heated for 6 hours. After refluxing, let cool and pour into water, add hydrochloric acid to acidify,
The organic layer was extracted using diethyl ether. The obtained ether solution was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by silica gel column chromatography. The obtained (+)-p- (3-trifluoromethylheptyloxy) benzyl alcohol was 4.4 g ▲ [α] ²⁸ _D
▼ + 1.0 ▲ [α] ²⁷ ₄₃₅ ▼ + 2.4 (c5.0 chloroform).

Step 3) Preparation of 4- [4 '-(4 "-octylphenyl) benzyloxy] -1- (3-trifluoroheptyloxy) phenyl (+)-p- (3-trifluoromethylheptyloxy) benzyl alcohol 0.58 g of thionyl chloride (1.5 ml)
After heating under reflux for 5 hours, excess thionyl chloride was distilled off to obtain a chloride. p-octyl biphenol 0.62g T
The solution was dissolved in 7 ml of HF, reacted with sodium hydride, and a solution prepared by dissolving chloride in 2 ml of dimethyl sulfoxide in a solution previously prepared as a sodium salt was added dropwise, followed by heating under reflux for 4 hours. After completion of the reaction, the reaction solution was poured into water, acidified with hydrochloric acid, and extracted with diethyl ether. The ether solution was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain 0.5 g of the desired product ▲ [α] ³⁴ ₄₃₅ ▼ + 3.6
(C0.5 CHCl _3).

Example 2 Preparation of 5-dodecyl-2- [4 '-[4 "-(3-trifluoromethylheptyloxy) benzyloxy] phenyl] pyrimidine 5-dodecyl-2- [4'-[4 ″
-(3-Trifluoromethylheptyloxy) benzyloxy] phenyl] pyrimidine was prepared.

(+)-P obtained by the method of steps 1) and 2) of Example 1
0.58 g of-(3 trifluoromethylheptyloxy) benzyl alcohol was heated under reflux in thionyl chloride (1.5 ml) for 5 hours, and then excess thionyl chloride was distilled off to obtain a chloride. 0.68 g of 5-dodecyl-2- (p-hydroxyphenyl) pyrimidine is dissolved in 7 ml of THF, sodium hydride is allowed to act on it, and a chloride dissolved in 2 ml of dimethyl sulfoxide is added dropwise to a solution previously prepared as a sodium salt. Was added and the mixture was heated to reflux for 4 hours. After completion of the reaction, the reaction solution was poured into water, acidified with hydrochloric acid, and extracted with diethyl ether. The ether solution was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain 0.17 g of the desired product. ▲ [α] ²⁹
₄₃₅ ▼ + 4.7 (c1, CHCl ₃ ) Example 3 A liquid crystal composition A containing the liquid crystal compound produced in Example 1 as a compounding component was prepared. As a comparative example, a liquid crystal composition B containing no liquid crystal compound of Example 1 was also prepared. The phase transition temperatures and spontaneous polarizations of liquid crystal compositions A and B are shown below.

Next, prepare two 0.7 mm thick glass plates, form an ITO film on each glass plate, create a voltage application electrode,
Further, SiO ₂ was vapor-deposited on this to form an insulating layer. Silane catpurin agent on glass plate [KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.]
Rotate the 0.2% isopropyl alcohol solution at 2000 rpm.
It was applied for 15 seconds at the speed of and surface-treated. After this
It was heat-dried at 120 ° C. for 20 minutes.

Further, a polyimide resin precursor [Toray Industries, Inc. SP-510] 2% dimethylacetamide solution was applied on a glass plate with an ITO film surface-treated with a spinner at a rotation speed of 2000 rpm.
It was applied for 2 seconds. After the film formation, a heating condensation baking treatment at 300 ° C. was performed for 60 minutes. At this time, the thickness of the coating film was about 700 °.
The coating after the baking is rubbed with an acetate flocked cloth, then washed with an isopropyl alcohol solution and sprayed with alumina beads having an average particle diameter of 2 μm on one glass plate, and each rubbing axis is changed. Align the glass plates so that they are parallel to each other, and glue the glass plates together using an adhesive sealant [Rixon Bond (Chitsuso Corporation)].
The cells were dried by heating at 100 ° C. for minutes. When the cell thickness of this cell was measured by a Bereck phase plate, it was about 2
μm.

Here, each of the ferroelectric liquid crystal compounds A and B prepared above was vacuum-injected into a cell prepared in a homogeneous mixed liquid state under an isotropic phase. By slow cooling from the isotropic phase at 0.5 ° C./h, a ferroelectric liquid crystal device was prepared.

Using this ferroelectric liquid crystal device, the optical response (transmission light amount change 0 to 90%) is detected by applying a peak-to-peak voltage of 30 V, and the response speed (hereinafter referred to as optical response speed) is detected. ) Was measured. The results are shown below.

Example 4 A polyimide resin precursor [manufactured by Toray Industries, Inc.] on a glass substrate on which an ITO (Imdium Tim Oxide) film was formed as a transparent electrode.
SP-510] to form a film by spinner coating, then 300
The polyimide film was baked at 60 ° C. for 60 minutes. Next, this coating film was subjected to orientation treatment by rubbing to make cells so that the rubbing treatment axes were orthogonal to each other (cell interval 8 μm).
A nematic liquid crystal composition (Rixon GR-63: Chitso Co., Ltd., biphenyl liquid crystal mixture) was injected into the above cell to form a TN (twisted nematic) type cell, which was observed with a polarizing microscope to find that the reverse domain ( It was found that a striped pattern had occurred.

A liquid crystal mixture obtained by adding the liquid crystalline compound (1 part by weight) of Example 1 of the present invention to Rixon GR-63 (99 parts by weight) was used to observe a TN cell in the same manner as above. The domain was not seen and the nematic phase had good homogeneity. From this, it was found that the liquid crystal compound of the present invention was effective in preventing reverse domains.

〔The invention's effect〕

A liquid crystal device using the liquid crystal composition containing the liquid crystalline compound of the present invention can be a liquid crystal device having excellent responsiveness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C07C 69/96 9546-4H C07C 69/96 Z C07D 239/26 C07D 239/26 C09K 19/20 9279 -4H C09K 19/20 19/30 19/30 19/34 19/34 G02F 1/13 500 G02F 1/13 500 // C07M 7:00 C07M 7:00

Claims (3)

(57) [Claims] 1. A liquid crystal compound represented by the following general formula (1). (However, in the above formula (1), R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkyl group having 1 to 12 carbon atoms, X
Is a single bond, -O-, Or Y is —CH ₂ O— or —OCH ₂ —, Z is —OCH ₂
CH ₂ −, or Is either. C ^* is an asymmetric carbon atom. Note that k, m, and n are independently selected from 0, 1, and 2 and k + m + n is 2 or 3. ) 2. A liquid crystal composition containing at least one liquid crystal compound represented by the following general formula (1). (However, in the above formula (1), R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkyl group having 1 to 12 carbon atoms, X
Is a single bond, -O-, Or Y is —CH ₂ O— or —OCH ₂ —, Z is —OCH ₂
CH ₂ -or Is either. C ^* is an asymmetric carbon atom. Note that k, m, and n are independently selected from 0, 1, and 2 and k + m + n is 2 or 3. ) 3. A liquid crystal device using a liquid crystal composition containing at least one liquid crystal compound represented by the following general formula (1). (However, in the above formula (1), R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkyl group having 1 to 12 carbon atoms, X
Is a single bond, -O-, Or Y is —CH ₂ O— or —OCH ₂ —, Z is —OCH ₂
CH ₂ -or Is either. C ^* is an asymmetric carbon atom. Note that k, m, and n are independently selected from 0, 1, and 2 and k + m + n is 2 or 3. )