JPH01207280A - Liquid crystal-formable compound, liquid crystal composition containing said compound and liquid crystal element using said compound - Google Patents

Abstract

NEW MATERIAL:A liquid crystal-formable compound of formula I (R1 is ethyl; R2 is 1-16 alkyl; C* is asymmetric carbon atom). EXAMPLE:P-(5-Dodecyl-2-pyrimidyl)P'-2'-fluorobutyloxyphenyl. USE:Useful as a liquid crystal composition. The compound of formula I has a high polarity and a low viscosity. The spontaneous separation of a liquid crystal composition containing the compound of formula I increases and the composition is low viscous. Liquid crystal elements using the liquid crystal composition have high response speeds and can prevent the generation of the reverse domains of nematic liquid crystal. For example, liquid crystal elements such as ferroelectric liquid crystal elements or twisted nematic liquid crystal elements can be obtained. PREPARATION:2-Fluoroalkane acid of formula II is used as a starting raw material to provide the compound of formula I as shown in the reaction formula.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel liquid crystal compound, a liquid crystal composition containing the same, and a liquid crystal element using the liquid crystal composition.

[Prior Art] As a conventional liquid crystal element, for example, M-Shut (M,
5chadt) and Double Helfrich (W.

11elfrich) 'yi, 'Applied Physics Letters'° (applied to 'Physi
Vol. 18, No. 4 (published February 15, 1971), pp. 127-128, "Voltage Day Pendant Optical Activity"
・Of a Twisted Nematic Liquid Crystal” (“VoltageDependent
0Ptical Activity of a
Twisted Nematic Liquid Cr
twisted nematic (
A device using a Twisted Ne1Iatic) liquid crystal is known. However, this TN liquid crystal has a problem in that crosstalk occurs during time division driving using a matrix electrode structure with high pixel density, so the number of pixels is limited.

Furthermore, its use as a display has been limited due to its slow electric field response and poor viewing angle characteristics.

Furthermore, a display element is known in which a switching element using a thin film transistor is connected to each pixel, and each pixel is switched. However, the process of forming the thin film transistor on the substrate is extremely complicated, and it is difficult to use a large-area display element. There are some problems that make it difficult to create.

To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices has been proposed by Clark (C
1ark) and Lagerwall (JP-A-56-1072]6, US Pat. No. 4,167,924, etc.). Chiral smectic C is generally used as a liquid crystal with bistability.
A ferroelectric liquid crystal having a phase (Sac") or an H phase (Sall") is used.

This ferroelectric liquid crystal has spontaneous polarization, so it has a very fast response speed, and it can also develop a bistable state with memory properties.It also has excellent viewing angle characteristics, so it has a large capacity. Suitable as screen display material.

Furthermore, since the materials used as ferroelectric liquid crystals contain asymmetric carbon, in addition to being used as ferroelectric liquid crystals that utilize their chiral smectic phase, they can also be used as optical elements such as the following. can.

1) Those that utilize the cholesteric-nematic phase transition effect in the liquid crystal state [Jay Jay Wysocki, A. Adams, and W. Haas, "Physics Reuyou Letters J (J, J.

Wysoki, A., Adams and W.H.
aas; Phys, Rev.

Left, ), 20.1024 (1968) ),
2) One that utilizes the White-Tiller type guest-host effect in the liquid crystal state (D.L. White, G.M. Taylor, “Sharnal of Applied Physics J (D, L, White and G,
N, Taylor; J, Appl, Phys.
), 45.4718 (1974)), etc. are known. Omit detailed explanations of individual methods, or
It is important as a display element and a modulation element.

In such a method using the electro-responsive optical effect of a liquid crystal, it is said that it is preferable to introduce a polar group in order to improve the responsiveness of the liquid crystal. Particularly in ferroelectric liquid crystals, it is known that the response speed is proportional to the spontaneous polarization, and it is desired to increase the spontaneous polarization in order to increase the speed. From this point of view, B-Keller (p, ni e
showed that it is possible to increase spontaneous polarization and speed up the response speed by directly introducing a chlorine group into an asymmetric carbon (C.R. Academy Science).
(C, R, Acad, Sc, Paris), 28
2G, 639 (1976)).

However, the chlorine group introduced into the asymmetric carbon is chemically unstable and has the disadvantage of decreasing the stability of the liquid crystal phase due to its large atomic radius, and there is a desire to improve this. There is.

On the other hand, functional materials required for optical elements characterized by having optical activity are often synthesized via optically active intermediates, but the optically active intermediates used conventionally include 2. - Methyl butanol, secondary octyl alcohol, secondary butyl alcohol, p-(2-methylbutyl)benzoic acid chloride, secondary phenethyl alcohol, amino acid derivatives, camphor derivatives, cholesprol derivatives, etc. are listed, and optically active intermediates such as Polar groups were rarely introduced into the body. For this reason, the method of increasing spontaneous polarization by directly introducing a polar group into an asymmetric carbon atom has not been used effectively.

[Invention or problem to be solved] The present invention has been made in view of the above points.

That is, the present invention provides a liquid crystal compound that has increased polarity by directly introducing a stable fluorine group with a large dipole moment into an asymmetric carbon atom, and contains at least one type of the liquid crystal compound to improve the electric field responsiveness of the liquid crystal. It is an object of the present invention to provide a liquid crystal composition with improved liquid crystal composition and a liquid crystal element using the liquid crystal composition.

[Means for Solving the Problem] and [Operation] The present invention has been made to achieve the above-mentioned object, and the first aspect [JJ is represented by the following general formula [1] (wherein R1 is The compound is related to a liquid crystal compound represented by an ethyl group, R2 is an alkyl group having carbon atoms a1 to [6], and C8 is an asymmetric carbon atom.

Further, the second invention relates to a liquid crystal composition containing at least one type of liquid crystal compound represented by the general formula [11].

Furthermore, a third invention relates to a liquid crystal element characterized by using a liquid crystal composition containing at least one type of liquid crystal compound represented by the general formula [1].

The present invention will be explained in detail below.

The liquid crystalline compound represented by the above general formula [1] of the present invention is preferably used in the application filed by the present applicant (Japanese Patent Application No. 62-77
It is synthesized from an optically active 2- to fluoroalkanoic acid represented by the following general formula [2] shown in the specification of No. 699).

υ (In the formula, R+, C'' are as defined above) In addition, the 2-fluoroalkane represented by the general formula [2] is synthesized by Ohler and Welfe, Synthesis.
s) 652 (1974) from amino acids.

Next, its main synthetic routes are shown.

R, -CIIC112011 (In the formula, R,, R2, C'' are as defined above) The liquid crystal compound of the present invention has a compound in which R1 in the general formula [l] is an ethyl group and the carbon atom chain is short. Therefore, when a liquid crystal composition is prepared, the liquid crystal compound of the present invention has a characteristic that the liquid crystal compound of the present invention By adding , a liquid crystal composition having a faster electric field response speed can be obtained even though the magnitude of spontaneous polarization is about the same.

Furthermore, the liquid crystal composition of the present invention contains at least one liquid crystal compound represented by the general formula [1] as a compounding component. When combined with a ferroelectric liquid crystal as shown in (13), the spontaneous polarization increases and the response speed improves.
I have something to do.

In such a case, the liquid crystal compound represented by the general formula [1] of the present invention may be added to the resulting liquid crystal composition in an amount of 0.1 to
It is preferable to use it in a proportion of 6% by weight, particularly 1 to 90% by weight.

p-decyloxybenzylidene=p'-amino-2-methylbutylcinnamate (DOBAMBG) p-hexyloxybenzylidene-p'-amino-2-chloropropylcinnamate (IIOBAc:PC) P-decyloxybenzylidene-p '-amino-2-methylbutyl-α
-Cyanocinnamate (DOBAMBCC) p-tetradecyloxybenzylidene-p'-amino-2-methylbutyl-α-cyanocinnamate (TDOBAMBCG)
p-octyloxybenzylidene-p'-amino-2-
Methylbutyl-α-chlorocinnamate (OOBAM
B(:C)p-octyloxybenzylidene-p'-amino-2-methylbutyl-α-methylcinnamate (2
-methylbutyl)ester-4'-octylaniline (MBRA 8)oxybiphenyl-4-carboxylate 4-hexyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'
-Carboxylate 4-octyloxyphenyl-4-
(2"-Methylbutyl)biphenyl-4'-carboxylate 4-hebutylphenyl-4-(4"-methylhexyl)biphenyl-4'-carboxylate (I3) 4-(2"-methyltutyl)phenyl-4- (4″-Methylhexyl)biphenyl-4′-carboxylate In addition, the liquid crystalline compound represented by the general formula [11] of the present invention can be used as a liquid crystal compound as shown in the following formulas (14) to (18). By blending it with a non-chiral smectic liquid crystal, a liquid crystal composition capable of being used as a ferroelectric liquid crystal can be obtained.

In this case, the liquid crystal compound represented by the general formula [1] is added in an amount of 0.1 to 99% by weight, particularly 1 to 90% by weight of the resulting liquid crystal composition.
It is preferable to use % by weight.

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

C811,704) (Sawa cooite 0C9H,.

(4-nonyloxyphenyl)-4'-octyloxybiphenyl-4-carboxylate 4.4'-decyloxyazoxybenzene 2-(4'-
hexyloxyphenyl)-5-(4-hexyloxyphenyl)pyrimidine 120°C 189°C 2
16°CCr y s t, −>Sta C←−−
→SmA←−−→Iso.

2-(4'-octyloxyphenyl)-5-nonylpyrimidine Ca It 170W COO+OCs It + +
4'-Pentyloxyphenyl-4-octyloxybenzoate Here, the symbols indicate the following phases, respectively.

Crystal: crystalline phase, Sa+A: smectic A phase.

SmB: smectic B phase, 5IIIC: smectic C phase, N: nematic phase, Iso: isokichi phase.

Furthermore, by using a liquid crystal composition containing at least one type of liquid crystal compound represented by the general formula [1] of the present invention, a liquid crystal element such as a ferroelectric liquid crystal element or a Reisteudo nematic liquid crystal element can be obtained. I can do it.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Optically active p-(5-dodecyl-2-pyrimidyl)p'-
Production of 2'-fluorobutyloxyphenyl Following step 1
), 2), optically active p-(5-dodecyl-2-pyrimidyl) p'-2'-fluorobutyloxyphenyl was produced.

Step l) (Production of 2-fluorobutyl lyl-toluenesulfonic acid 0.23 g of lithium aluminum hydride under nitrogen atmosphere)
(6.0 mmol) in 311 l of dry diethyl ether
), and a solution of 0.64 g (6.0 mmol) of (-)-2-fluorobutanoic acid dissolved in diethyl ether 3+if was added dropwise to the ice-cooled solution. Thereafter, the mixture was allowed to react at room temperature for 3 hours, a saturated aqueous sodium sulfate solution was added, and the ether layer was separated by decantation.

After drying the ether solution over anhydrous sodium sulfate, the ether was distilled off to obtain crude 2-fluorobutanol. I got og.

The 2-fluorobutanol obtained above was mixed with pyridine (1
, 42 g) of p-toluenesulfonic acid chloride 1.14
g (6.0 mmol) by stirring at room temperature for 3 hours.

After the reaction was completed, 3NllCj) was added to make the mixture acidic (pH 3), and the mixture was extracted with benzene. After drying this solution over anhydrous sodium sulfate, the solvent was distilled off, and the resulting crude product was purified by column chromatography (mobile phase: benzene/hexane = 2/1 mixed solvent). p-
Toluenesulfonic acid 2-fluorobutyl ester was added to 0.
95g (:1.9smol) was obtained. Yield 64% [α]
, :'+9.81. [α] ::5 +25.1
(CO, 958° CII□C!2) Step 2) (-)-p-(5-dodecyl-2-pyrimidyl) -p
Production of '-2'-fluorobutyloxyphenyl p-(5-dodecyl-2- pyrimidyl)
Phenol 0.102g (0,:lOmmol) and (-
)-p-Toluene J Lefonic acid 2-fluorobutyl ester 0.075g (0,:lOmmol) was added to dimethylformamide l+aR, and the mixture was stirred for 6 hours.
The reaction was carried out at 100°C. The reaction water was added and extracted with diethyl ether. The solution was dried over anhydrous sodium sulfate, the solvent was distilled off, and the result was purified by F1 layer chromatography (developing solvent: benzene). The result was (-)-p-(5-
dodecyl-2-pyrimidyl)-p'-2'-fluorobutyloxyphenyl or 0.084 g (0.21 mmol)
) obtained. Yield 70% [C! ] 0610.0.
[α] <;s 8.8 (c O, 50°C112
CRt) Examples 2 to 4 In the same manner as in Example 1, p-(5-octyl-2-pyrimidyl)phenol or p-( 5-nonyl-2-pyrimidyl)phenol, or p-(5
-decyl-2-pyrimidyl)phenol, the following compound was obtained.

The data on phase transition temperature and optical rotation are shown in Table 1 together with the data of Example 1.

(Note) 1) Solvent for specific rotation measurement - dichloromethane 2) Cr
yst, : crystal, Iso, : Tokichi phase.

SA: Smectic A phase S3. S4: Smectic phase (unidentified) Example 5 A liquid crystal composition A containing the liquid crystal compound produced in Example 4 as a compounding component was prepared. Further, as a comparative example, a liquid crystal composition B not containing the liquid crystal compound of Example 4 was also prepared. The phase transition temperatures of each of liquid crystal compositions A and B are shown below, and the spontaneous polarization is shown in Table 2.

Liquid Crystal Composition A> Phase Transition Temperature (°C) <Liquid Crystal Composition B> Phase Transition Temperature (°C) Table 2 Next, two glass plates with a thickness of 0.71 were prepared, and on each glass plate An rro (indium tin oxide) film was formed on the substrate to form a voltage application electrode, and 5in2 was further vapor-deposited thereon to form an insulating layer. A 0.2% isopropyl alcohol solution of a silane coupling agent (manufactured by Shin-Etsu Chemical, KBM-602) was applied onto the glass plate at a rotational speed of 2000 r, p, s for 15 seconds to perform surface treatment. Thereafter, it was heated and dried using lZOoC for 20 minutes.

Furthermore, a polyimide resin precursor (Toshi ■, 5P-510) was placed on a glass plate with an ITO film that had undergone surface treatment.
% dimethylacetamide solution at rotation speed 2000 r, p,
It was applied for 15 seconds using a spinner. *Extraction and heat condensation firing treatment was performed at 300°C for 60 minutes. The thickness of the coating film at this time was about 700.

The fired coating was subjected to a rubbing treatment using an acetate flocked cloth.

Then, after washing with isopropyl alcohol solution and scattering alumina beads with an average particle size of 2 pots on one glass plate, the rubbing axes of each plate were parallel to each other. Glass plates were bonded together using a commercially available product manufactured by J.D. Co., Ltd., and dried by heating at 100° C. for 60 minutes to create a cell. The cell thickness of this cell was measured using a Berek phase plate and was found to be about 2 pm.

Here, ferroelectric liquid crystal composition A prepared previously.

B was vacuum injected into the prepared cell in a uniformly mixed liquid state under the Tokichi phase. A ferroelectric liquid crystal element was prepared by slow cooling at 0.5°C/h from the Tokichi phase.

Using this ferroelectric liquid crystal element, the response speed was measured by applying a voltage with a peak-to-peak voltage of 30 V to detect the optical response (change in amount of transmitted light from 0 to 90%) under crossed Nicols. The results are shown in Table 3.

Table 3 Example 6 A film was formed by spinner coating using a polyimide resin precursor (manufactured by Toshi ■, 5P-510) on a glass substrate on which an ITO film was formed as a transparent electrode, and then heated at 300°C for 5 minutes.
A polyimide film was formed by baking for 0 minutes. Next, this film was subjected to an orientation treatment by rubbing, and cells were prepared so that the rubbing axes were perpendicular to each other (cell spacing: 8JL).
m).

A nematic liquid crystal composition [Rixon GR-6:
l: manufactured by Chisso V4, biphenyl liquid crystal mixture] was injected,
When a TN (twisted nematic) type cell was observed using a polarizing microscope, it was found that a reverse domain (striped pattern) was formed.

A liquid crystal mixture obtained by adding the liquid crystal compound of Example 2 of the present invention (1 part by weight) to the Rixon GR-6:l (99 parts by weight) was observed as a TN cell in the same manner as above. , no reverse domains were observed, and a nematic phase with good uniformity was observed.

From this, it was confirmed that the liquid crystalline compound of the present invention is effective in preventing reverse domains.

[Effects of the Invention] As explained above, according to the present invention, polarity is increased by directly introducing a fluorine group into an asymmetric carbon atom of a liquid crystal compound, and furthermore, a pyrimidine ring and a benzene ring are directly connected to the skeleton. By having such a structure, the viscosity becomes low, and the spontaneous polarization of the liquid crystal composition containing it increases, and the viscosity is low.

In addition, a liquid crystal element using the liquid crystal composition has a fast response speed, and furthermore, it is possible to prevent the occurrence of reverse main in nematic liquid crystal.

Agent: Hiroshi Watari Hebe

Claims (3)

[Claims] (1) The following general formula [1] ▲Mathematical formulas, chemical formulas, tables, etc.▼[1] (In the formula, R_1 is an ethyl group, R_2 has 1 to 1 carbon atoms
A liquid crystalline compound represented by an alkyl group of 6, C^* represents an asymmetric carbon atom. (2) The following general formula [1] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [1] (In the formula, R_1 is an ethyl group, R_2 has a carbon atom number of 1 to 1
A liquid crystal composition comprising at least one liquid crystal compound represented by an alkyl group of 6 and C^* represents an asymmetric carbon atom. (3) The following general formula [1] ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ [1] (In the formula, R_1 is an ethyl group, R_2 has 1 to 1 carbon atoms
A liquid crystal element characterized in that it uses a liquid crystal composition containing at least one liquid crystal compound represented by an alkyl group of 6 and C^* represents an asymmetric carbon atom.