JPS62123153A - Biphenol derivative and liquid crystal composition and optical switching element containing same - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is 1-20C alkyl; the group of formula II is 1,4-phenylene which is substituted with at least one halogen atom; Q* is optically active alkyl). EXAMPLE:4-{4'-[(S)-2-methylbutyloxy]biphenyl}.3-fluoro-4-decylo-xybenz oate. USE:A component of a liquid crystal composition having chiral smectic phase. It is a colorless ferroelectric liquid crystal compound having excellent chemical stability to light and moisture and is usable as a liquid crystal material having application potential to a liquid crystal display element having quick response and memorizing property. The compound is expected to be useful as a photo- switching element for display. PREPARATION:The compound of formula I can be produced by reacting the carboxylic acid of formula II with a chlorination agent such as SOCl2 and reacting the resultant acid chloride of formula IV with a biphenol monoether of formula V in a solvent in the presence of a basic substance such as pyridine.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel liquid crystal compound and a liquid crystal composition, and in particular, to provide a liquid crystal material having ferromagnetic properties, which is different from conventional liquid crystal compounds. The object of the present invention is to provide a liquid crystal material that can be used for liquid crystal display elements, which has particularly excellent high-speed response and memory performance compared to other liquid crystal materials.

<Prior art> Liquid crystal display elements have excellent characteristics such as low voltage operation, low power consumption, ability to display thin light, and light-receiving type that does not cause eye fatigue, so they are widely used as various display elements. It is used.

Currently, the display method is T N (Twist
edNematic) The most common material is a nematic liquid crystal called gourd. but,
Although this TNW display element has all of the above-mentioned excellent features, it has the disadvantage that the response is extremely slow compared to other light-emitting display systems such as CRT.

Therefore, various restrictions have been imposed on the application to display elements that require a fast response, such as moving picture screens on televisions and heads of high-speed printers.

In addition to TNN, liquid crystal display devices include guest-host (GH) W, controlled birefringence (ECB), and phase change (PC) devices.
) type, thermal effect type, etc. have been developed, each with 46!
l is attached, but in terms of responsiveness, both are T.
Compared to the N type, it could not be said that particularly high speed could be obtained. For these display elements, a dual-frequency drive type was developed as a display system capable of obtaining high-speed response, and although slight improvements were made in response, it was still difficult to say that it was fully satisfactory. For this reason, attempts have been made to develop new display systems with even better responsiveness.

In line with this objective, ferroelectric liquid crystals have recently been emitted (Mayer et al., Journal de Physique, 36 L69 (1975)).

Display elements using this ferroelectric liquid crystal can have a response 100 to 1000 times faster than conventional liquid crystals and a memory effect due to bistability (Clark et al.
Applied Fixtures Letters, i6 899 (1
980)), can be expected to be applied to a wide variety of display devices, including video devices such as televisions, high-speed optical cameras, and other devices.

The liquid crystal phase of the ferroelectric liquid crystal belongs to a tilted chiral smectic phase, and among these, the chiral smectic C phase (hereinafter abbreviated as SC0 phase) has the lowest viscosity and is practically desirable.

Liquid crystal compounds exhibiting the SCa phase have been used in the field of detection, and many have already been mentioned.

A typical example is ■-2-methylbutyl p-decyloxypenzylidene aminocinnamer (DORAMB), which is considered to be the first ferroelectric liquid crystal synthesized.
(abbreviated as C) and its homologues can be mentioned. This is still one of the most commonly used liquid crystal compounds for studying the physical properties and orientation of ferroelectric liquid crystals, and it is used to compare and study important physical properties of ferroelectric liquid crystals, such as spontaneous polarization and pitch. It is also one of the reference substances in cases where However, DOBAMBC
and its series compounds: ■Lack stability against light■
Lacking stability against moisture■Itself is colored■S
The temperature range in which the C0 phase is exhibited is narrow, from 76° to 93°, and is much higher than room temperature, which is disadvantageous, and it is not satisfactory from a practical standpoint.

In order to improve these drawbacks, chemically stable esters have recently been studied, and some cases have already been reported.

As a review, 1) Gutsdoby et al., Liquid Crystal and Ordered Urn Furi, -is, 4, P1-2
) /, Doby et al., Moncular Crystals and Liquid Crystals, 110.175 (198
4) etc.

However, among the compounds introduced in these publications, so-called 2ffi compounds containing two benzene rings in the molecule have S
The 01 phase is often monotropic, and the so-called tricyclic compounds containing three benzene rings tend to have a too high temperature range in the sc" phase. For this reason, all of these compounds are The present inventors have already introduced halogen atoms such as fluorine and chlorine into specific positions of such compounds, thereby significantly lowering their transition temperatures, especially their melting points. We have reported that it is possible to obtain a highly practical liquid crystal compound (Patent application 1791/1986).
%I! Showa 60-71628. %i Showa 60-81688.
(Japanese Patent Application No. 60-90676, Japanese Patent Application No. 60-98712, etc.), the present invention has a similar object.

<Problems to be Solved by the Invention> The present inventors focused on ester compounds as liquid crystal compounds with excellent chemical stability against light and moisture, and achieved ferroelectricity near room temperature by using them alone or in combination. We have conducted extensive research into whether it is possible to obtain a new liquid crystal compound that can take a liquid crystal phase, especially a chiral smectyl or C phase,
The present invention, which led to the present invention, also aims to provide a liquid crystal display element having high-speed response using such a novel liquid crystal compound or composition.

<Means for solving the problem> The liquid crystal compound in the present invention is characterized by being a biphenol derivative represented by the following general formula I.

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, a 1,4-7 enylene group, and Qo represents an optically active alkyl group.) The liquid crystal composition of the present invention also includes: It is a liquid crystal composition consisting of a plurality of compounds represented by general formula I (hereinafter abbreviated as compound I), or consisting of at least one compound I and a liquid crystal compound other than compound I.

Ferroelectricity in liquid crystals appears when the liquid crystal takes a tilted chiral smectic phase, and Compound I lowers its melting point and other transition points by mixing it with other materials (including compounds such as those), and lowers its melting point and other transition points, and lowers the temperature at room temperature. A stable ferroelectric liquid crystal composition can be obtained in the vicinity.

Compound 1 has D in the molecule as shown in the general formula ①.
Unlike OBAMBC, it does not have a trans-double stack that is unstable to light or an azomethine bond (-〇H=N-) that is unstable to water pressure. Its rounding is completely stable to light and water. Also, unlike DOBAMBC, it is not colored, and is itself colorless.

In order for a liquid crystal to exhibit an SC* phase (or other chiral smectic phase), it must be chiral. For this purpose, a method of introducing an optically active group such as G)-2-methylbutyl group or 2-octyl group into the molecule is generally adopted. Compound I also achieves this objective by linking (1)-2-methylbutyl group or other suitable optically active alkyl group through an ether bond.

In addition, the functional groups R and Qo in general formula i are compound I
It is additionally noted that hydrogen may be substituted with a halogen atom or other substituent group as long as the identity is not impaired.

Next, the method for synthesizing Compound I will be described.

Compound ■ is an acid chloride expressed by the general formula (wherein,
R is an alkyl group having 1 to 20 carbon atoms, 1, 4-7
Enire/Greetings. Hereinafter, it will be referred to as acid chloride (■). ) and a biphenol monoether represented by the general formula (where Qo represents an optically active alkyl group).

It can be easily obtained by reacting biphenol derivative (hereinafter referred to as biphenol derivative weight) in the presence of a basic substance such as pyridine.

Here, acid chloride (1) is referred to as carb/acid (2) under the corresponding carboxylic acid represented by the general formula (2). ), it can be obtained by treating it with a chlorinating agent such as thionyl chloride, and it is also possible to cleave the filtrate by distillation or recrystallization, but it is usually a crude product obtained by distilling off excess thionyl chloride. It can be used as is in the next process.

The carboxylic acid can be easily converted to rC by alkylating the halogen-substituted 4-hydroxybenzoic acid represented by the general formula V by a conventional method.
The compound represented by this general formula V can be obtained by
Some of them are commercially available, and they are easy to synthesize. (Gray et al., Molecular Crystals &
Crystals, 67 1 (1981)).

On the other hand, biphenol derivative I is a compound when Q" is @-2-methylbutyl group, and it is also a compound when Q" is other optically active group (X is chlorine, bromine, iodine, etc.). A leaving group such as a halogen or a para-toluenesulfonyloxy group can be added to a divinol.

Now, the obtained liquid crystal compound or composition can be used as a liquid crystal display cell by forming a thin film with a uniform thickness of 1 pm to 20 μm between two transparent electrode plates.

In the display cell, liquid crystal molecules need to be homogeneous monodomains with their long axes parallel to the electrode planes, with uniform orientation. For this purpose, liquid crystal is transformed from an isotropic liquid phase by subjecting the cell surface to an alignment treatment such as rubbing or vapor deposition, by applying an electric or magnetic field, by creating a temperature gradient, or by using a combination of these methods. Generally, a method is used in which the phase is gradually cooled to achieve orientation, and uniformly oriented monodomain cells can be obtained with the compound or composition of the present invention by such a method.

<Effects of the Invention> Although the present invention is as described above, the uninvented compound (2) has a higher level of stability in the Examples described below, compared to DOBAMBC, which has been conventionally referred to as a substitute strong #S conductive liquid crystal compound. As shown, it can be easily produced industrially, is colorless in itself, and has excellent chemical stability against light and moisture. Further, in the composition of the present invention, as with general liquid crystal compositions, a lower melting point is observed compared to a single compound, and it can be used at room temperature.

Furthermore, the strong 1111 liquid crystal compound and composition of the present invention, like conventional ferroelectric liquid crystals, has an extremely high response speed of more than 100 times that of nematic liquid crystals.

Therefore, it is extremely promising as an optical switching element for display.

<Examples> The present invention will be specifically explained below with reference to Examples, but of course the gist and scope of the present invention are not limited by these Examples.

Note that temperature means °C.

Example 1 (Synthesis of 4-(4'-((S)-2-methylbutyloxy)biphenyl).5-fluoro-4-decyloxybenzoate) Synthesis from 6-fluoro-4-decyloxybenzoic acid and thionyl chloride 5-fluoro-4-decyloxybenzoic acid chloride 2.38 f (6.7 mmol) and a
-(4'-((S)-2-methylbutyloxy)phenyl)phenol t79t (7.0 mmol) was dissolved with methylene chloride 60- and pyridine 30-, and heated and stirred at 35° to 40° for 6 hours. and reacted.

After leaving to stand to room temperature, 100% ethyl acetate was added, and the mixture was washed successively with 10% diluted water, saturated sodium chloride solution, water, and saturated brine, and then dehydrated and dried over anhydrous sodium sulfate. The crude crystals obtained by distilling off the solvent were purified by silica gel column chromatography (developing solvent: chloroform-hexane), and further recrystallized from ethanol.
- Crystals 2.51F of (4'-((S) -2-methylbutyloxy)biphenyl)-3-fluoro-4-decyloxybenzoate were obtained (yield: $65.1).

The chemical structure of the product is determined by nuclear magnetic resonance spectroscopy (NMR)
, infrared absorption spectrum (IR), if spectrum (MS
) was confirmed.

51.5-5.0 (3H, m), δ1.2-1.5 (16H, m), δQ, 8-1.
1 (9H,m, -CR2)IR: 1735,1
615,1505,1290,1220゜1140.1
075,935,805.760 (am') MS:
554(P) This compound showed SC phase. The transition temperature is described below. The transition temperature is measured using a differential scanning calorimeter (DSC).
A polarized light microscope equipped with a temperature control stage was also used.

S04 + N": 168°, N"→I: 151°, melting point 106-1070 (N1 is chiral nematic phase,
2) represents an isotropic liquid phase) Examples 2 to 4 In Example 1, 5-fluoro-4-decyloxybenzoic acid chloride was replaced with 2) 3-fluoro-4
-octylox7benzoic acid chloride, 3) 3-fluoro-
A similar reaction was carried out using 4-dodecyloxybenzoic acid chloride, 4) 5-fluoro-4-tetradecyloxybenzoic acid chloride, etc. to obtain 4-(4'-((S)-2-methylbutyloxy). ) biphenyl)・3-fluoro-4-dimethyloquinopenzoate, 4-(4'-((Sl-2-
methylbutyloxy)biphenyl)N6-fluoro-4
= Dodecyloxypennoate, 4- (4'-((
S)-2-methylbutyloxy)biphenyl)-3-fluoro-4-tetradecyl dibennoate was obtained.

These NMR, IR&:1. , showed the same pattern as in Example 1 except for the peak corresponding to the methylene chain and the absorption intensity ratio, and MS gave the respective parent peaks.

These compounds also have liquid crystal properties, and the transition points of the liquid crystal phase are shown in Table 1.
They are summarized in .

Example 5 Synthesis of C4-(C-((s)-2-methylbutyloxy)via z dik l 113-rioa-4-decyloxybenzoate] In Example 1, 3-fluoro-4-decyloxybenzoate Using 5-chloro-4-decyloxybenzoic acid 531F instead of acid chloride, 4-(4'-((group-2-
Methylbutyloxy)biphenyl)・3-chloro-4-
Decyl benzoate 168f was obtained (yield 67%).

δt5 ~ 2.0 (5H, m), δ1.2 ~ 1.5 (16H, m), δa, s ~ t1 (9H, m, -CR2) This compound exhibits the SC'' phase, and its transition temperature is It is described below.

SC"-"N": 11Q, 5°, N"-+i:
1290 Melting point 1 [17,50 Example 6 [4~(4
'-((S)-2-methylbutyloxy)biphenyl)
・2-Fluoro-a-f syloxyben/nee) No+
In the actual msi, 2-fluoro-4-decyloxybenzoic acid chloride &145F ((101 mol) was used instead of 3-fluoro-4-decyloxybenzoic acid chloride,
Reaction and purification were carried out in the same manner, and 4-(4'-((mark-2-methylbutyloxy)biphenyl)・2-fluoro-4-
Decyloxybenzoate 3.74F was obtained (yield 70
blood).

61.5~20 (3H, m), δ1,1~ts (16, m), δα8~1.1 (9H, m, -CR2) ■R: 17
20.1620, 1505.1290, 1215, 11
70°1105, 995.860.770.640 (
am-1) The liquid crystal phase transition temperature of this product is described below.

N'')→I; ii6°, melting point 71-72° Example 7
[Synthesis of 4-(4'-((S)-2-methylbutyloxy)biphenyl).2-chloro-4-tetradecyloquine benzoate] In Example I, 3-fluoro-4-decyloxinebenzoic acid In place of chloride, 2-chloro-4-nato-2decyloxybenzoic acid chloride was used and the reaction was carried out in the same manner.
Purification was performed to obtain 4-(4'-((group-2-methylbutyloxy)biphenyl).2-chloro-4-tetradecyloxybenzoatett5tt (It51751)
.

61.5-2 [(3H, m), δ1.15-1.5 (24H, m), δα85-1.
1 (9H, rn, -CR2)I R: 1720.
1610.1505.1280.1215.1170゜1110, 1040.845.810.760 (er
a-') The liquid crystal phase transition temperature of this product is described below.

N"→I: 82.6°, melting point 76° In the table, . indicates the existence of that phase, and the number to the right of . indicates the transition temperature to a higher phase in the V temperature range.

In addition, - indicates that the phase does not exist.Example 8 [Creation of thin film cell for liquid crystal display] The liquid crystal compound obtained in Example 1 is heated to form an isotropic liquid phase, and this is thickened. Two polyimide sheets with a spacer of 2.0 μm in diameter
Filled between glass transparent electrodes that have been subjected to 2-pin orientation treatment,
A thin film cell was created.

The mixture was slowly cooled at a rate of 5° per minute to orient the chiral nematic phase, and further cooled to 168° or less to obtain a uniform chiral smectic C phase monodomain.

An electric field (10V I Do Hz) is applied to this cell at 120°.
When the optical switching operation was detected using a photomultiplier by applying an O rectangular wave, the response speed was approximately 4.
It was 00μSee. This K means that a liquid crystal display element with a fast response speed was obtained.

Example 9 [V4 product of liquid crystal composition showing SC2 phase] 60 parts of the compound obtained in Example 4, 10 parts of the compound obtained in Example 5, 60 parts of the compound obtained in Example 7, 4 −((
S)-2-Methylbutyloxy)phenyl 6-fluoro-4-dodecyloxybenzoate 65ii11.4
-((S)-2-methylbutyloxy)phenyl 6'
-60 parts of chloro-4'-octyloxybiphenyl-4-carboxylate and 35 parts of 4-((S)-2-methylbutyloxy)phenyl 3'-chloro-4'-tetradecyloxydipenzoate. A liquid crystal composition was prepared by mixing and melting. This composition is in the N'' phase at 95° and at 79°
At 78°, it became an SA phase, and at 78° it became an SC phase, and the SC phase was maintained until room temperature. As a result, a liquid crystal composition exhibiting ferroelectricity near room temperature was obtained. This composition was cooled and crystallized, and its melting point was measured to be 60°.

Claims (1)

[Claims] 1. General formula I ▲There are mathematical formulas, chemical formulas, tables, etc.▼...
・(I) (In the formula, R is an alkyl group having 1 to 20 carbon atoms, ▲There are mathematical formulas, chemical formulas, tables, etc.) ▼ is a 1,4-phenylene group substituted with at least one halogen atom. ,Q
^* represents an optically active alkyl group. ) A novel biphenol derivative. 2. The biphenol derivative according to claim 1, wherein Q^* is (S)-2-methylbutyl group. 3. General formula I ▲There are mathematical formulas, chemical formulas, tables, etc.▼...
・(I) (In the formula, R is an alkyl group having 1 to 20 carbon atoms, ▲There are mathematical formulas, chemical formulas, tables, etc.) ▼ is a 1,4-phenylene group substituted with at least one halogen atom. ,Q
^* represents an optically active alkyl group. ) A liquid crystal composition containing as a component at least one compound I represented by: 4. The liquid crystal composition according to claim 3, wherein Q^* is a (S)-2-methylbutyl group. 5. The liquid crystal composition according to claim 3 or 4, which contains two or more kinds of compound I. 6. The liquid crystal composition according to claim 3 or 4, which contains at least one compound I and a liquid crystal compound other than compound I. 7. The liquid crystal composition according to claim 3, 4, 5 or 6, which has a chiral smectic phase. 8. General formula I ▲There are mathematical formulas, chemical formulas, tables, etc.▼...
・(I) (In the formula, R is an alkyl group having 1 to 20 carbon atoms, ▲There are mathematical formulas, chemical formulas, tables, etc.) ▼ is a 1,4-phenylene group substituted with at least one halogen atom. ,Q
^* represents an optically active alkyl group. ) An optical switching element comprising at least one of the compounds shown in the following.