JPH075499B2 - Liquid crystal compound and liquid crystal composition containing the same - 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 using the liquid crystal composition, more specifically, an optically active liquid crystal compound, The present invention relates to a liquid crystal composition containing the same and a liquid crystal device using the liquid crystal composition.

BACKGROUND ART Conventional liquid crystal elements include, for example, M.Sc
hadt) and W. Helfrich, “Applied Physics Letters” (“Applied
Physics Letters ") Volume 18, Issue 4 (Published February 15, 1971), pages 127-128," Voltage Dependant Optical Activity of a Twisted Nematic Liquid Crystal ". (“Volt
age Dependent Optical Activity of a Twisted Nemati
c Liquid Crystal ") is known to use a 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, the use as a display has been limited because the electric field response is slow and the viewing angle characteristics are poor.

In addition, a display element of a type in which a switching element using a thin film transistor is connected to each pixel and switching is performed for each pixel is known, but a step 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, US 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 phase-stable state with a memory property. Further, it has a large viewing angle characteristic and thus has a large capacity and a large capacity. Suitable as a display material for screens.

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

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 (1984), etc. are known.
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 liquid crystal, it is said that it is preferable to introduce a polar group in order to enhance the response of the liquid crystal. Especially in ferroelectric liquid crystals, it is known that the response speed is proportional to the spontaneous polarization,
It is desired to increase the spontaneous polarization for speeding up. From this point of view, P. Keller et al. Showed that by introducing a chlorine group directly into the asymmetric carbon, the spontaneous polarization can be increased and the response speed can be increased (CRAcad.Sc.Paris,
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 -Methyl butanol, 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. For this reason, the method of increasing spontaneous polarization by directly introducing a polar group into an asymmetric carbon atom has not been effectively used.

OBJECT OF THE INVENTION The present invention has been made in view of the above points. That is, the present invention provides a liquid crystal compound in which a polar group is enhanced by directly introducing a stable and large dipole moment fluorine group into an asymmetric carbon atom, and a liquid crystal compound in which at least one kind of the liquid crystal compound is contained. It is intended to provide a composition.

In the present invention, it is easy to change the length of the alkyl group, which allows H. Arnold, Z. Phys. Chem., 226, 146 (196
An object of the present invention is to provide a liquid crystal compound capable of controlling the type and temperature range of a liquid crystal phase developed in a liquid crystal state as shown in 4) and a liquid crystal composition containing the compound as at least one compounding component. To do.

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and has the general formula (I) (Here, R ₁ is an alkyl group having 4 to 18 carbon atoms or an alkoxy group, R ₂ is an alkyl group having 1 to 16 carbon atoms,
C ^* represents an asymmetric carbon atom.

Represents a 1,4-phenylene group or a pyrimidine-2,5-diyl group, l and m are 0, 1 or 2 (provided that l + m ≧ 1),
n shows 0 or 1, p shows the integer of 1-10. The present invention provides a liquid crystal compound represented by

The present invention also provides a liquid crystal composition containing at least one liquid crystal compound as a blending component, and a liquid crystal device using the liquid crystal composition.

DETAILED DESCRIPTION OF THE INVENTION The liquid crystalline compound represented by the above general formula (I) is preferably a fluoro compound represented by the following general formula (II) shown in the specification of the applicant (February 5, 1987). It is synthesized via an optically active intermediate such as an alkane derivative.

(Here, A represents an OH group or a halogen atom.) For example, via these optically active fluoroalkane derivatives, the following synthetic route (an example of A = OH is shown) is represented by the general formula (I). A liquid crystal compound is obtained.

(Where R ₁ , R ₂ , l, m, n, p, Is as defined above. The liquid crystal composition of the present invention contains at least one liquid crystal compound represented by the general formula (I) as a blending component. For example, when this liquid crystalline compound 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, it is preferable to use the liquid crystal compound of the present invention represented by the general formula (I) in an amount of 0.1 to 99% by weight, particularly 1 to 90% by weight of the obtained liquid crystal composition.

Further, by compounding with a smectic liquid crystal which is not chiral itself as shown in the following formulas 1) to 5), a composition usable as a ferroelectric liquid crystal can be obtained.

In this case, the liquid crystal compound of the present invention represented by the general formula (I) is used in an amount of 0.1 to 99% by weight, particularly 1 to 9% by weight of the obtained liquid crystal composition.
It is preferably used at 0% by weight.

Such a composition can obtain a large spontaneous polarization due to the content of the liquid crystal compound of the present invention.

Here, the symbols indicate the following phases, respectively.

Cryst .: crystalline phase, SmA: smectic A phase, SmB: smectic B phase, SmC: smectic C phase, N: nematic phase, Iso .: isotropic phase.

Further, the liquid crystalline compound represented by the general formula (I) is effective in preventing the generation of the reverse domain in the TN type cell by adding it to the nematic liquid crystal. In this case, it is preferable to use the liquid crystal compound of the formula (I) in an amount of 0.01 to 50% by weight of the obtained liquid crystal composition.

Also, by adding to nematic liquid crystal or chiral nematic liquid crystal, as chiral nematic liquid crystal,
It can be used as a liquid crystal composition in a phase transition type liquid crystal device or a white Taylor type guest-host liquid crystal device. In this case, it is preferable to use the liquid crystal compound of the formula (I) in an amount of 0.01 to 80% by weight of the obtained liquid crystal composition.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 P-n-decyloxybenzoic acid-2 represented by the above formula
-(2'-Fluorooctyloxy) ethyl ester was prepared by the following steps.

That is, 0.47 g of pn-decyloxybenzoic acid (1.7 m
(mol) was heated under reflux with 4 ml of thionyl chloride for 90 minutes, and then unreacted thionyl chloride was distilled off to obtain a corresponding acid chloride.

Next, 0.38 g (3.4 mmol) of triethylenediamine was dissolved in 5 ml of dry benzene, potassium hydroxide was added, and the mixture was dried. This solution was placed in a container containing 0.384 g (2.0 mmol) of ethylene glycol mono (2-fluorooctyl) ether and stirred. This solution was added dropwise to the above acid chloride,
After the dropping, the mixture was stirred at 50 ° C for 1 hour. Then, the reaction solution was cooled to room temperature, 48 mg (2 mmol) of sodium hydride suspended in 2 ml of dry benzene was added, and the mixture was heated with stirring at 50 ° C. for 1 hour and then heated under reflux for 2 hours.

The reaction solution was cooled to room temperature, 5.5 ml of 1N hydrochloric acid was added, and further 10 ml of water was added. The organic layer was separated and the aqueous layer was extracted with benzene. Then, the benzene layer was combined with the organic layer, washed with a 1N sodium carbonate aqueous solution, and then dried over anhydrous magnesium sulfate, and benzene was distilled off to obtain 0.626 g of a crude product. This is separated and purified by a silica gel column, pn
0.392 g (0.87 mmol) of decyloxybenzoic acid-2- (2'-fluorooctyloxy) ethyl ester was obtained.

▲ [α] ²⁰ _D ▼: -1.6 ° (C = 3.1, CH ₂ Cl ₂ ) IR (cm ^-1 ): 2940, 2850, 1720, 1610, 1515, 1470, 1320, 1280, 12
60, 1170, 1103, 840, 760.

Example 2 In place of pn-decyloxybenzoic acid, p'-n-decyloxybiphenylcarboxylic acid was used, and the following Example 1 was used.
By carrying out the same reaction treatment as described above, p'-n-decyloxybiphenylcarboxylic acid-2- (2'-fluorooctyloxy) ethyl ester was obtained.

▲ [α] ²⁰ _D ▼: −2.1 ° (C = 3.0, CH ₂ Cl ₂ ) IR (cm ⁻¹ ): 2930, 2860, 1720, 1605, 1470, 1300, 1275, 1205, 11
50, 1130, 825, 760.

Example 3 Optically active 5-octyl-2- [4 represented by the above formula
-(2'-Fluorooctyloxyethyloxy) phenyl] pyrimidine was prepared by the following steps.

That is, 1.2 g (6.25 mmol) of optically active ethylene glycol mono-2-fluorooctyl ether and 1.4 g of pyridine.
9 g (18.8 mmol) was ice-cooled, 1.32 g (6.9 mmol) of paratoluenesulfonic acid chloride was added, and the mixture was stirred for 3.5 hours.
To this reaction solution, 6.3 ml of 2N hydrochloric acid was added, and the mixture was extracted 3 times with 10 ml of dichloromethane. The organic layer was washed with water, dried and the dichloromethane was distilled off to obtain 2.09 g of crude product (60.4 mmol).
Got This is generated by column chromatography,
1.81 g (5.2 mmol) of tosylate compound was obtained. Yield 83.7%,
▲ [α] ¹⁷ _D ▼ -2.4 ° (C = 2, CH ₂ Cl ₂ ).

Next, 0.91 g (2.63 mmol) of this tosylate compound and 0.51 g of 5-octyl-2- (4-hydroxyphenyl) pyrimidine
0.5 ml of 1-butanol was added to (1.8 mmol) and stirred. To this solution, an alkaline solution prepared by dissolving 0.083 g (2.08 mmol) of sodium hydroxide in 2 ml of 1-butanol was added, and the mixture was heated under reflux at 130 ° C for 6 hours. Water (15 ml) was added to the reaction solution, the mixture was extracted 3 times with 10 ml of benzene, dried and benzene was distilled off to obtain 1.00 g of a crude product. This was produced by silica gel column chromatography and then by recrystallization to give the desired product, optically active 5-octyl-2.
[4- (2'-fluorooctyloxyethyloxy)
Phenyl] pyrimidine (0.50 g, 1.09 mmol) was obtained.

Yield 60.6%, ▲ [α] ¹⁵ _D ▼: -1.6 ° (C = 1.0, CHC
l ₃ ).

IR (KBr disc) [cm ^-1 ]: 2865, 2830, 1615, 1590, 1550, 1520, 1470, 1440, 13
70, 1340, 1300, 1260, 1170, 1130, 1070, 920, 900,
840, 810, 785, 720, 700.

Examples 4 to 12 By the method according to Example 3, Example 4 shown in Table 1 below.
~ 12 compounds were obtained.

Table 1 also shows the phase transition temperatures of the compounds of Examples 1 to 12 obtained as described above.

In the table, Cryst. Represents a crystalline state, SmC ^* represents a chiral smectic C phase, Ch. Represents a cholesteric phase, Iso. Represents an isotropic phase, and S ₃ represents an unidentified smectic phase.

Example 13 A liquid crystal composition A containing the compound produced in Example 6 as a blending component was prepared. As a comparative example, a liquid crystal composition B containing no compound of Example 6 was also prepared. The composition, phase transition temperature and spontaneous polarization of each of the liquid crystal compositions A and B are shown below.

<Liquid crystal composition A> Phase transition temperature (℃) <Liquid crystal composition B> Phase transition temperature (℃) Spontaneous polarization (nC / cm ₂ ) Next, two 0.7 m-thick glass plates were prepared, an ITO film was formed on each glass plate, a voltage application electrode was prepared, and SiO ₂ was vapor-deposited on this to form an insulating layer. Silane coupling agent [KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.] on glass plate 0.2
% Isopropyl alcohol solution was applied at a rotation speed of 2000 rpm for 15 seconds for surface treatment. After this 120 ℃
It was heat dried 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, the film was heat-condensed and baked at 300 ° C. for 60 minutes. At this time, the film thickness of the coating film was about 700Å.

The baked coating 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. Align the glass plates so that they are parallel to each other, and glue the glass plates together using an adhesive sealant [Rixon Bond (Chisso Corporation)].
A cell was prepared by heating and drying at 100 ° C for a minute. When the cell thickness of this cell was measured with a Berek phase plate, it was about 2
was μm. Here, each of the ferroelectric liquid crystal compounds A and B prepared above was vacuum-injected into the prepared cell in an isotropic phase in a homogeneous mixed liquid state. A ferroelectric liquid crystal device was prepared by gradually cooling from the isotropic phase at 0.5 ° C / h.

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

Response speed (msec) Example 14 A polyimide resin precursor [SP manufactured by Toray Industries, Inc.] on a glass substrate on which an ITO (Indium Tin Oxide) film was formed as a transparent electrode.
-510] to form a film by spinner coating, then 300 ℃
And baked for 60 minutes to form a polyimide film. Next, this coating was subjected to orientation treatment by rubbing to make cells so that the rubbing treatment axes were orthogonal to each other (cell spacing 8 μm).
A nematic liquid crystal composition [Rixon GR-63: biphenyl liquid crystal mixture manufactured by Chisso Corp.] was injected into the above cell to form a TN (twisted nematic) type cell, which was observed with a polarization microscope to reveal a reverse domain (striped pattern). Was found to have occurred.

When a liquid crystal mixture obtained by adding the liquid crystalline compound (1 part by weight) of Example 2 of the present invention to Rixon GR-63 (99 parts by weight) was observed as a TN cell in the same manner as above,
The reverse domain was not seen, and the nematic phase had good uniformity. From this, it was found that the liquid crystal compound of the present invention is effective in preventing the reverse domain.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C09K 19/34 9279-4H 19/46 9279-4H G02F 1/137 9315-2K (72) Inventor Goji Kadono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuaki Katagiri 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. The following general formula (I): (Here, R ₁ is an alkyl group having 4 to 18 carbon atoms or an alkoxy group, R ₂ is an alkyl group having 1 to 16 carbon atoms,
C ^* represents an asymmetric carbon atom. and Represents a 1,4-phenylene group or a pyrimidine-2,5-diyl group, l and m are 0, 1 or 2 (provided that l + m ≧ 1),
n shows 0 or 1, p shows the integer of 1-10. ) A liquid crystal compound represented by: 2. The following general formula (I) (Here, R ₁ is an alkyl group having 4 to 18 carbon atoms or an alkoxy group, R ₂ is an alkyl group having 1 to 16 carbon atoms,
C ^* represents an asymmetric carbon atom. and Represents a 1,4-phenylene group or a pyrimidine-2,5-diyl group, l and m are 0, 1 or 2 (provided that l + m ≧ 1),
n shows 0 or 1, p shows the integer of 1-10. ) A liquid crystal composition comprising at least one liquid crystal compound represented by 3. The following general formula (I) (Here, R ₁ is an alkyl group having 4 to 18 carbon atoms or an alkoxy group, R ₂ is an alkyl group having 1 to 16 carbon atoms,
C ^* represents an asymmetric carbon atom. and Represents a 1,4-phenylene group or a pyrimidine-2,5-diyl group, l and m are 0, 1 or 2 (provided that l + m ≧ 1),
n shows 0 or 1, p shows the integer of 1-10. ) A liquid crystal device comprising a liquid crystal composition containing at least one liquid crystal compound represented by