JPH0667913B2 - Optically active 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 and a liquid crystal composition containing the same.

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 (1971, February 2)
Issued on March 15th), pages 127-128, "Voltage Dependant Optical Activity.
Of a Twisted Nematic Liquid Crystal ”(“ Voltage Dependent Optical Activity of
It is known to use twisted nematic liquid crystal shown in a Twisted Nematic Liquid Crystal ”). This TN liquid crystal is used for time-division driving using a matrix electrode structure with high pixel density. However, the number of pixels is limited because of the problem of crosstalk.

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 a bistable liquid crystal element has been proposed as a solution to the drawbacks of the conventional type liquid crystal element.
rk) and Lagerwall (JP-A-56-107216, US Pat. No. 436).
7924 specification). As a liquid crystal having bistability, a chiral smectic C phase (SmC ^* ) is generally used.
Alternatively, a ferroelectric liquid crystal having an H phase (SmH ^* ) 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.

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 W.
Haas; Phys.Rev.Lett., 20,1024 (1968)), 2) Utilizing the white Taylor type guest-host effect in the liquid crystal state ((DLWhite and GNTaylo
r; J. Appl. Phys., 45 , 4718 (1974)), 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 such a point, 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 -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. 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, and as a result, the kind and temperature of the liquid crystal phase developed in the liquid crystal state as shown in H. Arnold, Z. Phys. Chem., 226, 146 (1964). It is an object of the present invention to provide a liquid crystal compound capable of controlling the range and a liquid crystal composition containing the liquid crystal compound as at least one compounding component.

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and has the general formula (I) (Here, k represents an integer of 1 to 14, m represents an integer of 1 to 10, n represents an integer of 1 to 16, and C ^* represents an asymmetric carbon atom.). The present invention provides an optically active liquid crystal compound and a liquid crystal composition containing at least one compounding component thereof.

DETAILED DESCRIPTION OF THE INVENTION The optically active liquid crystal compound represented by the general formula (I) of the present invention is preferably prepared from the optically active 2-fluoro-1-alkanol shown in the specification of Japanese Patent Application No. 60-232886. It is synthesized by the synthetic route shown.

(Here, k, m, and n are as defined above.) Examples of the liquid crystalline compound of the present invention thus obtained are shown below.

5-n-butoxymethyl-2- [4 '-(2 "-fluorooctyloxy) phenyl] pyrimidine-5- [2'-n-butoxyethyl] -2- [4"-
(2-Fluorooctyloxy) phenyl] pyrimidine · 5- [2′-n-decyloxyethyl] -2- [4 ″
-(2-Fluorodecyloxy) phenyl] pyrimidine-5- [2'-n-dodecyloxyethyl] -2-
[4 "-(2-fluorooctyloxy) phenyl]
Pyrimidine 5- [2'-n-butoxyethyl] -2- [4 "-
(2-Fluorododecyloxy) phenyl] pyrimidine · 5- [2′-n-hexyloxyethyl] 2- [4 ″
-(2-Fluorodecyloxy) phenyl] pyrimidine-5- [4'-n-butoxybutyl] -2- [4 "-
(2-Fluorooctyloxy) phenyl] pyrimidine · 5- [7′-n-ethoxyheptyl] -2- [4 ″-
(2-Fluorooctyloxy) phenyl] pyrimidine · 5- [10′-n-ethoxydecyl] -2- [4 ″-
(2-Fluorooctyloxy) phenyl] pyrimidine.5- [3'-n-hexyloxypropyl] -2-
[4 ″-(2-Fluorohexadecyloxy) phenyl] pyrimidine The optically active liquid crystalline compound represented by the formula (I) of the present invention has the carbon number of the alkane moiety of 2-fluoro-1-alkanol as a starting material. Although it is possible to widely change the above n by changing it, the present invention provides that n is an alkyl group of 1 to 16.

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

In such a case, the fluoroalkane derivative 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 90% by weight of the obtained liquid crystal composition. Is preferred.

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, it is preferable to use the fluoroalkane derivative 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.

Such a composition can obtain a large spontaneous polarization due to the content of the fluoroalkane 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.

Further, the fluoroalkane derivative 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, 0.01 to 5 of the obtained liquid crystal composition
It is preferred to use the fluoroalkane derivative of formula (I) in a proportion of 0% by weight.

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 element or a white Taylor type guest-host type liquid crystal element. In this case, 0.01 to 80 of the obtained liquid crystal composition
It is preferable to use the fluoroalkane derivative of the formula (I) in a proportion of weight%.

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

Example 1 5- (2′-n-butoxyethyl) -2- [4 ″-(2
Preparation of -fluorooctyloxy) phenyl] pyrimidine.

The above compound was synthesized by the following three steps.

(Step 1) 4,6-dihydroxy-5- (2'-n-butoxyethyl) -2- [4 "-(2-fluorooctyloxy)
Phenyl] pyrimidine production.

0.08 g (3.5 m) of sodium in 3 ml of dry methanol
mol) and completely dissolved, and then p- (2-fluorooctyloxy) benzamidine hydrochloride 0.35 g
(1.16 mmol) and diethyl 2- (n-butoxyethyl) malonate 0.30 g (1.16 mmol) were added, and 8
The mixture was refluxed at 0 ° C for 9 hours, and further stirred at room temperature for 9 hours. After completion of the reaction, 2N-hydrochloric acid was added, and the mixture was filtered, washed with water and ethanol, and dried at 120 ° C for 1 hour. The crystals were recrystallized from 1 ml of dimethylformamide (DMF) to give 4,6-dihydroxy-5- (2'-n-butoxyethyl) -2-.
[4 "-(2" -fluorooctyloxy) phenyl]
0.36 g (0.80 mmol) of pyrimidine was obtained. Yield 69%.

(Step 2) 4,6-dichloro-5- (2'-n-butoxyethyl)
Preparation of 2- [4 "-(2-fluorooctyloxy) phenyl] pyrimidine.

4,6-dihydroxy-5- (2'-n-butoxyethyl) -2- [4 "-(2-fluorooctyloxy)
To 0.36 g (0.80 mmol) of phenyl] pyrimidine,
0.24 ml of N, N-diethylaniline and 2.0 ml of phosphoryl chloride were added, and the mixture was refluxed at 110 ° C. for 30 hours. After completion of the reaction, excess phosphoryl chloride was distilled off, a sodium hydroxide solution was added, and the mixture was extracted with ether. Extract 1N
-After washing with hydrochloric acid and water, by thin layer chromatography (TLC) (benzene: hexane = 1: 1),
6-dichloro-5- (2'-n-butoxyethyl) 2-
[4 "-(2-fluorooctyloxy) phenyl]
0.23 g (0.47 mmol) of pyrimidine was obtained.

Yield 60%, m.p. p. 28 ° C-34 ° C, ▲ [α] ^29.6 _D
▼ -7.00 ° (c0.658, (Step 3) 5- (2′-n-butoxyethyl) -2- [4 ″ -2
Preparation of -fluorooctyloxy) phenyl] pyrimidine.

4,6-dichloro-5- (2 'in ethanol (95%)
-N-butoxyethyl) -2- [4 "-(2-fluorooctyloxy) phenyl] pyrimidine 0.23 g
(0.47mmol) and 5% -palladium activated carbon 10m
g, and magnesium oxide 0.038 g (0.94 mmol) were added, and hydrogen substitution was carried out in an atmospheric pressure hydrogen adding device. After reaction T
By LC (dichloromethane) 0.10 g (0.24 mmo) of 5- (2'-n-butoxyethyl) -2- [4 "-(2-fluorooctyloxy) phenyl] pyrimidine
l) got. Yield 51%.

The product exhibited the following properties.

▲ [α] ^32.0 _D ▼ + 0.33 ° (c0.612, Et
₂ O).

Phase transition temperature (℃) (Sm3: smectic phase other than SmA and SmC phases) Example 2 5- (2'-n-butoxyethyl) -2- [4 "-(2
-Fluorododecyloxy) phenyl] pyrimidine (k = 4, m = 2, n = 10) was synthesized according to the production method of Example 1. The characteristic values are shown below.

Specific rotation [α] _D + 0 ° (26.0 ° C.) (c = 0.892, (C ₂ H ₅ ) ₂
O) Phase transition temperature (℃) Example 3 5- (2'-n-hexyloxyethyl) -2- [4 "
-(2-Fluorodecyloxy) phenyl] pyrimidine (k = 6, m = 2, n = 8) Synthesized according to the production method of Example 1. The characteristic values are shown below.

Specific rotation [α] _D + 1.52 ° (24.8 ° C.) (c = 0.656, (C ₂
H ₅ ) ₂ O) Phase transition temperature (℃) Example 4 A liquid crystal composition A containing the liquid crystalline compound produced in Example 1 as a blending 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 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 ) Temperature (° C.) Liquid crystal composition A Liquid crystal composition B 40 4.7 1.2 30 10.0 2.0 2.0 Two 0.7 mm thick glass plates were prepared, and An ITO film is formed on a glass plate, a voltage application electrode is created,
Further, SiO ₂ was vapor-deposited on this to form an insulating layer.

A silane coupling agent [KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.] 0.2% and an isopropyl alcohol solution were applied on a glass plate at a rotation speed of 2000 rpm for 15 seconds for surface treatment. After that, a heat drying treatment was performed at 120 ° C. for 20 minutes.

Furthermore, a polyimide resin precursor [Toray Industries, Inc. SP-510] 2 was placed on a glass plate with an ITO film that had been surface-treated.
% Dimethylacetamide solution at a rotation speed of 2000 rpm
Was applied for 15 seconds using the spinner of 60 minutes after film formation,
A heat condensation calcination treatment was performed at 300 ° C. At this time, the film thickness of the coating film was about 700Å.

The coating after the baking is rubbed with an acetate flocked cloth, then washed with an isopropyl alcohol solution, and sprayed on one glass plate with alumina beads having an average particle diameter of 2 μm. Put the glass plates parallel to each other, and glue the glass plates together using an adhesive sealant [Rixon Bond (Chisso Corporation)], and
A cell was prepared by heating and drying at 100 ° C. for 0 minutes. When the cell thickness of this cell was measured with a Berek phase plate,
It was about 2 μm.

Here, the ferroelectric liquid crystal compounds A and B prepared previously were vacuum-injected into the cells prepared in the homogeneous mixed liquid state under the respective isotropic phases. 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, an optical response (transmission light amount change of 0 to 90%) was detected by applying a peak-to-peak voltage of 30 V to measure the response speed. The results are shown below.

Response speed (msec) Temperature (° C.) Liquid crystal composition A Liquid crystal composition B 40 0.06 0.55 30 0.12 0.93 Example 5 On a glass substrate on which an ITO (Indium Tin Oxide) film was formed as a transparent electrode Polyimide resin precursor [Toray Industries, Inc. SP-
510] to form a film by spinner coating,
The polyimide film was baked at 0 ° C. for 60 minutes. 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).
m). Nematic liquid crystal composition [Rixon GR
-63: Biphenyl liquid crystal mixture manufactured by Chisso Corporation] was injected to obtain a TN (twisted nematic) type cell, which was observed by a polarization microscope, and it was found that a reverse domain (striped pattern) was generated.

When 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 observed as a TN cell in the same manner as above, a reverse No domain was observed 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.

Claims (2)

[Claims] 1. The following general formula (I) (Here, k represents an integer of 1 to 14, m represents an integer of 1 to 10, n represents an integer of 1 to 16, and C ^* represents an asymmetric carbon atom.). Optically active liquid crystalline compound. 2. The following general formula (I) (Here, k represents an integer of 1 to 14, m represents an integer of 1 to 10, n represents an integer of 1 to 16, and C ^* represents an asymmetric carbon atom.). A liquid crystal composition comprising at least one optically active liquid crystalline compound.