JPH03261746A - Compound containing oxymethylene bond - Google Patents

Abstract

NEW MATERIAL:A compound shown by formula I (R<1> is 4-12C optically active alkyl; R<2> is 2-10C alkyl; ring A is 1,4-phenylene or 2-fluoro-1,4-phenylene; m and n are 0 or 1; Y is -CH2O- or -OCH2-). EXAMPLE:[4-[4-[4-[(R)-1-Methylheptyloxy]benzyloxy]phenyl]benzoic acid (S)-1-methyl heptyl ester. USE:A material for liquid crystal display having ferroelectricity and light switch element for display. Having possibility of use for liquid crystal device having especially excellent response and memory. PREPARATION:When Y is -CH2O-, a compound shown by formula II is reacted with a compound shown by formula IV in the presence of a base or when Y is -CH2O-, a compound shown by formula III is reacted with a compound shown by formula V in the presence of a base to give a compound shown by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel optically active compound useful as an electro-optical display material and a liquid crystal composition containing the compound. The present invention relates to a liquid crystal display material that has properties, and that can be used for liquid crystal devices that have particularly excellent responsiveness and memory performance compared to conventional liquid crystal materials.

[Prior art]

The currently widely used liquid crystal display elements are mainly of the TN type, which utilizes nematic liquid crystals, and although they have many advantages, their responsiveness is inferior to that of CRTs. The major drawback was that it was much slower than the light-emitting display method. Many liquid crystal display systems other than the TN type have been studied, but the current situation is that improvements in their responsiveness have not yet been made.

However, liquid crystal devices using ferroelectric smectic liquid crystals can respond 100 to 1000 times faster than conventional liquid crystal display elements, and have bistability, so even when the applied electric field is turned off, the display remains unchanged. It has recently become clear that memory (memory effect) can be obtained. For this reason, it has great potential to be used in optical shutter printer heads, thin large-screen televisions, and computer displays, and research and development is currently being conducted in various fields to put it into practical use.

The liquid crystal phase of ferroelectric liquid crystal belongs to the tilted chiral smectic phase, but in practical terms, the chiral smectic C (hereinafter abbreviated as Sc) phase, which has the lowest viscosity, is the one that has the lowest viscosity. Most desirable.

Liquid crystal compounds exhibiting the Sc'' phase (hereinafter abbreviated as Sc'' compounds) have been studied, and a large number of compounds have already been synthesized. However, the following conditions for use as a ferroelectric display element are met: (a) It must exhibit an Sc" phase over a wide temperature range including room temperature. (b) It must have an appropriate phase series on the high temperature side of the SC* phase. And, as a result of (c) having a large helical pitch, (c) having an appropriate tilt angle, (d) having low viscosity, and (e) having a relatively large spontaneous polarization, (b) good orientation is achieved. As a result of (g), (d), and (e), no compound has been known that alone satisfies the requirement of exhibiting high-speed response.

For this reason, liquid crystal compositions (hereinafter referred to as
Sc'' liquid crystal composition) is being studied.

As a method for preparing the liquid crystal composition, smectic C
(hereinafter abbreviated as SC) A common method is to add a chiral compound (hereinafter referred to as chiral compound) to a liquid crystal compound or composition that exhibits a phase (hereinafter referred to as SC base liquid crystal). However, in this method, unless the chiral dopant induces a very large spontaneous polarization, the spontaneous polarization of the Sc'' liquid crystal composition will become too small and it will not exhibit high-speed response. Although it is not necessary to exhibit a liquid crystal phase, it is desirable that the temperature range when added to the host liquid crystal is not too narrow.

Furthermore, in the SC0 phase and N1 phase in which a helix appears, if the helical pitch becomes short, the orientation is adversely affected. Therefore, in order to use a liquid crystal compound capable of exhibiting strong spontaneous polarization as a chiral dopant, it was necessary to adjust the helical pitch of the Sc'' liquid crystal composition by adding a chiral compound with the opposite direction of twist. In this case, if the direction of the spontaneous polarization of the chiral compound opposite to the twist direction is also opposite, the spontaneous polarization of the composition will cancel out and become smaller, and there are many troublesome problems in adjusting the helical pitch. Therefore, a compound used as the main component of a chiral dopant is desired to have not only strong spontaneous polarization but also a sufficiently long helical pitch.

On the other hand, for the purpose of adjusting the helical pitch, on the other hand, it is advantageous to use a compound with a very short helical pitch because only a small amount is required. Also, in a display system called a DHF system using ferroelectric liquid crystal, a compound having such a short helical pitch is advantageous. Moreover, such a compound can also be suitably used for STN liquid crystals and the like as additives for nematic liquid crystals.

As one of the representative optically active groups in compounds that have been used as chiral dopants,
Examples include an optically active group represented by CHs -COOCH-R (wherein R represents an alkyl group having 2 to 10 carbon atoms). Many compounds having this optically active group are also known as Sc8 liquid crystal compounds. Such compounds have relatively large spontaneous polarizations; for example, compounds with R=C, H, and - are known to exhibit values close to 100 nC/cm. (11th Liquid Crystal Discussion) (See p. 172 of the conference proceedings.) However, chiral dopants having spontaneous polarization of this level require a large proportion of the composition, and are not sufficient from the viewpoint of responsiveness.

[Problem to be solved by the invention]

The problem to be solved by the present invention is to induce extremely to large spontaneous polarization by mixing all of the chiral dopant or as a constituent component of the chiral dopant into the host liquid crystal, and to form the Sc'' phase in a wide temperature range including room temperature. It is an object of the present invention to provide a compound capable of providing a liquid crystal composition that exhibits a high degree of orientation, good alignment, low viscosity, and high-speed response, and also to provide such a composition.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides - Monka (1) Provides a compound represented by

In the above formula, R1 represents an optically active alkyl group having 4 to 12 carbon atoms, and is preferably an optically active group represented by the following formula: -Monoya%.

In this case, %R'' represents an alkyl group having 2 to 1 carbon atoms, but a linear alkyl group having 2 to 6 carbon atoms is particularly preferred.Alternatively, %R' is represented by the general formula %) An optically active group is preferred. In this case, R' represents an alkyl group having 2 to 6 carbon atoms, and a linear alkyl group is particularly preferred.

k represents an integer from 1 to 4. R3 has 2 to 10 carbon atoms
represents an alkyl group. AEjii represents a 1,4-phenylene group or a 2-fluoro-1,4-phenylene group. m and n each independently represent 0 or l, but m +
When n = O, the liquid crystallinity of the compound tends to deteriorate, and when m + n = 2, the viscosity of the compound tends to increase, so the case where m + n = 1 is preferred. Y represents -CH*O- or -0CR,-. In addition, when R1 is an optically active group represented by the formula -More (I), the absolute configuration of each of the two asymmetric carbon atoms in the molecule of the compound represented by -More (I) is (S ) arrangement and (R) arrangement, or a combination of (R) arrangement and (S) arrangement.

The compound represented by the general formula (I) according to the present invention can be produced, for example, as follows.

(1) When Y = -CH, ○- (2) When Y = OCHs CH3 (In the above reaction formula, R', R8, A ring, m and n are the same as in general formula (I) have meaning.

That is, the bromide represented by the corresponding general formula (II) or <m> and the phenol derivative represented by the general formula (rV) or (V) may be respectively reacted in the presence of a base. Each compound represented by the general formula (n), (m), (■) or (V) is known or can be easily obtained by conventional synthetic chemical techniques.

The compound represented by the general formula (I) of the present invention is obtained as described above, and the melting point, phase transition temperature, infrared absorption spectrum (IR
), nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS
), etc.).

Table 1 lists the phase transition temperatures of typical compounds represented by the general formula (I) thus produced.

The liquid crystal phase and phase transition temperature were measured using a polarizing microscope equipped with a variable adjustment stage and a differential scanning calorimeter (DSC), but the transition temperature may vary slightly depending on the purity of the sample or measurement conditions. It is something to do.

The purity of the product was confirmed by thin layer chromatography, gas chromatography, and high performance liquid chromatography.

/ The present invention also provides a liquid crystal composition. The liquid crystal composition of the present invention is a liquid crystal composition containing a compound represented by the general formula (1), and the compound represented by the general formula (1) is one of the optically active compounds added to the base liquid crystal as a chiral dopant. It is something that makes up part or all of something. Particularly preferably, a ferroelectric chiral smectic liquid crystal composition is obtained by adding a chiral dopant containing a compound represented by general formula (I) to a base liquid crystal exhibiting a smectic C (hereinafter abbreviated as Sc) phase. or a chiral nematic (hereinafter abbreviated as No) liquid crystal composition obtained by adding a compound represented by general formula (1) to a parent liquid crystal exhibiting a nematic (hereinafter abbreviated as N) phase. (hereinafter referred to as N@liquid crystal composition). This is a composition used for liquid crystal display elements such as N''' liquid crystal composition, TN type, or STN type.

The present invention also provides a liquid crystal display element using the above composition. In particular, when used as a ferroelectric smectic liquid crystal display element, the general formula (I ) One of the excellent features of the compound represented by is that the spontaneous polarization (Ps) is sufficiently large.

For example, in a Sc" liquid crystal composition in which 5% by weight of the compound shown in the Examples below is added to the Sc host liquid crystal, the Ps value at room temperature is as large as 3.8 nC/c+o". This is derived from (S)-2-methylbutanol, which is the most commonly used chiral source in liquid crystals.
compounds, such as (S)-2-methylbutyl p-decyloxybenzylidene aminobenzoate (DOBAMBC
) etc. alone, which is about 4 nC/cm", this is a very large value. This is because the two optically active groups in the compound represented by general formula (I) are compatible with each other. This is thought to be due to additive or synergistic effects, and thus
If it is added in an amount of about 2% by weight or more, it becomes possible to induce spontaneous polarization sufficient for high-speed response.

Furthermore, one of the excellent characteristics of the compound represented by the general formula (I) is that it has a relatively low viscosity. This is because the intermediate linking group is a low-viscosity dimethylene bond.

As mentioned above, the compound represented by the general formula (I) of the present invention is preferably used by being added to a liquid crystal composition rather than being used alone. In particular, as a chiral dopant, Sc
"It is effective to use it as a liquid crystal composition.The general formula (
Since the compound represented by 1) can induce sufficiently large spontaneous polarization in the liquid crystal composition, high-speed response can be achieved if it is added in an amount of about 1% by weight or more to the Sc host liquid crystal.

Moreover, such a small amount of addition hardly narrows the temperature range of the SC" phase. Therefore, when added alone,
Although it does not exhibit the Sc'' phase, it can be used satisfactorily.

Examples of the Sc compound to be used as the Sc host liquid crystal doped with the compound having an optically active group represented by the general formula (I) of the present invention include phenylbenzoate compounds represented by the following general formula (A) and general formula(
Examples include pyrimidine compounds represented by B).

...... (A) (wherein R" and R"' are each independently a linear or branched alkyl group, alkoxyl group, alkoxydicarbonyl group, alkanoyloxy group, or alkoxy represents a carbonyloxy group)... (B) (In the formula, Ro and R each have the same meaning as in the general formula (A).) Also, the general formula (A) A compound represented by general formula (C), including a compound represented by (B), can also be used for the same purpose.

...... (C) (wherein R" and Rh each have the same meaning as in the general formula (A), and the L ring and the M ring each independently represent 1. 4-phenylene group, 114-cyclohexylene group, pyrimidine-2,5-diyl group, pyrazine-2
,5-diyl group, pyridazine-3,6-diyl group, pyridine-2,5-diyl group, 1,3-dioxane-2,5
-represents a diyl group or a halogen-substituted product thereof,
They may be the same or different. Za is -C00-
-OCO-CHx OOCH! -CH, CH, -CmiC- or a single bond. ) Furthermore, for the purpose of expanding the temperature range of the Sc phase to a high temperature range, a three-modal compound represented by the general formula (D) can be used.

(In the formula, R1 and R1 each have the same meaning as in the general formula (A), and the L ring 1M ring and the N ring each independently represent the L ring and M ring of the general formula (C). has the same meaning as ring, and Zl and zb each independently represent the general formula (C
) has the same meaning as Zo. ) It is effective to mix these compounds and use them as an Sc host liquid crystal, but it is sufficient that the liquid crystal composition exhibits an Sc phase, and individual compounds do not necessarily have an S phase.
It is not necessary to show c-phase.

The general formula (I
) and, if necessary, other optically active compounds as chiral dopant, it is possible to easily obtain a liquid crystal composition that exhibits the Sc'' phase over a wide temperature range including room temperature. can.

The liquid crystal composition obtained by doping the compound represented by the general formula (I) of the present invention with other above-mentioned Sc compounds or Sc liquid crystal compositions is prepared by doping between two transparent glass electrodes.
It can be used as a display cell by encapsulating it as a thin film of about 20 ohm.

In order to obtain good contrast, uniformly oriented monodomains are required. Many methods have been tried for this purpose, but as a liquid crystal material, isotropic liquid phase (hereinafter abbreviated as I phase) → chiral nematic phase (hereinafter abbreviated as I phase)
It is abbreviated as N1 phase. )→Smectic A phase (hereinafter referred to as SA
Abbreviated as phase. )-xylsmectic C phase (hereinafter %S
(abbreviated as “C” phase), and N@
It is known that those having a large helical pitch in the N0 phase and the Sc'' phase, especially the N0 phase, exhibit good orientation.

In order to increase the helical pitch, it is sufficient to mix appropriate amounts of chiral compounds with opposite twist directions, but according to the present invention, a compound with a long helical pitch and, conversely, a compound with a long helical pitch for pitch adjustment can be mixed. This is extremely advantageous since both short compounds are obtained. In other words, although the helical pitch induced by the optically active group represented by the formula -More % is relatively small, the helical pitch induced by the compound by reversing the direction of the helical pitch induced by the other optically active group R' The pitch can be increased, and by making the orientation the same, the helical pitch induced by the compound can also be made very small. Each of these optically active groups is N1
The direction of the helical pitch induced in the phase is already well known, and the absolute configuration of the asymmetric carbon and the central skeleton (core) of the liquid crystal molecule are known.
It is determined by the number of atoms of the asymmetric carbon.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.
Of course, the gist and scope of the present invention are not limited to these examples.

The structure of the compound can be determined by nuclear magnetic resonance spectrum (NMR).
), infrared absorption spectrum (IR) and mass spectrum (
Confirmed by MS). The phase transition temperature was measured using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (DS).
C) was used in combination. (NuJol) in IR refers to measurements in suspension in liquid paraffin. N.M.
(CDCIS) in R is the solvent, S is the singlet, d
represents a doublet, and m represents a multiplet. Also, the temperature is
Represents °C. All "%" in the composition represents "wt% j.

Example 1 Synthesis of (S)-1-methylheptyl (4-[4-[4-((R)-1-methylhebutyloxy)benzylocyclophenyl]benzoate (N of Table 1 (compound 11)) ) (1-a,) Synthesis of 4-((R) -1-methylhebutyloxy)benzyl alcohol 3.06 g of lithium aluminum hydride was suspended in 60 ml of tetrahydrofuran (hereinafter abbreviated as THF).

To this suspension, 10.71 g of ethyl 4-((R)-1-methylhebutyloxy)benzoate was added under water cooling.
0slTHF solution was added dropwise over 1.5 hours. After stirring for 4 hours, excess hydride was destroyed by adding water and then hydrochloric acid. The precipitate was removed by decantation, washed with ethyl acetate, and the organic layers were combined and dried over anhydrous sodium sulfate. The crude product obtained by distilling off the solvent was purified using silica gel column chromatography to obtain 4-((R)-1-
Methylhebutyloxy)benzyl alcohol oil 4
．． 99g was obtained.

(1-b,) Synthesis of 4-((R)-1-methylhebutyloxy)benzyl bromide 4-((R)-1-methylhebutyloxy)benzyl alcohol obtained in (1-a,) 3. 59 g was dissolved in 1 liter of dichloromethane SO. To this solution, 2.00 g of phosphorus tribromide was added dropwise over 0.5 hours while cooling with water.

After stirring for an additional 4 hours at 25°C, anhydrous potassium carbonate was slowly added. The insoluble matter was filtered off and the solvent was distilled off, and the resulting crude product was purified using silica gel column chromatography to obtain an oily product of 4-(,(R)-1-methylhebutyloxy)benzyl bromide. 4.06 g of product was obtained.

(1-e, ) Synthesis of the title compound 4-(4-hydrobydiphenyl”) Benzoic acid 11 (S
)-1-Methylhebutyl 339B was dissolved in 10 liters of dimethylformamide (DMF). To this solution was added 130+ og of potassium t-butoxy and stirred.

To this mixed solution, add the 4-bromide ((1-b, ) obtained in
R)-1-methylhebutyloxy)benzyl 344. g
A solution of 3 ml of DMF was added dropwise at room temperature over 2 minutes. After stirring at room temperature for 4 hours, dilute hydrochloric acid and ethyl acetate were added to the reaction mixture, and the organic layer was washed with water.
Dehydrated with anhydrous sodium sulfate.

The crude product obtained by distilling off the solvent was purified using silica gel column chromatography to obtain 493 mg of white crystals of the title compound. The physical property values are shown below.

(NMR) (CDC1m) 0.61-1.99 (!l, 32H), 4.1
3-4.48(11,1)1), 4.99(s,2
H), 5.02-5.30 (m, 1ll),
6.87 (d, J=8.5Hz.

2B), 7.22(d, J=8.5Hz,
2H), 7.52(d, J=8.5Hz.

2H), 7.58(d, J=8.5Hz,
2H), 8.06(d, J=8.5Hz.

2B) (IR) (Nujol) 2930, 21160. 1710. 1605.
1510. 1290. 1115°995, 830
(cm-') Melting point 56.5°C Examples 2 to 4 Compounds Nos. 2 to 4 listed in Table 1 were obtained in the same manner as in Example 1.

Example 5 (Preparation of Sc" liquid crystal composition) A Sc matrix liquid crystal having the following composition was prepared.

The phase transition temperature (°C) of this Sc host liquid crystal is as follows.

13 68 73.5 83.
5Cr-4S c Mar-3A ;→N -□
1 (N represents a nematic phase, and ■ represents an isotropic liquid phase.

) This Sc host liquid crystal had a concentration of 95% and the N obtained in Example 1.

A liquid crystal composition consisting of 5% of compound No. 1 was prepared.

This Sc''' liquid crystal composition has a Sc'' phase at 68°C or lower.
The sA phase was shown at 72.5°C or below, and the N1 phase was shown at 79°C or below. Moreover, its melting point was unclear.

Example 6 (Preparation of display element) The Sc'' liquid crystal composition obtained in Example 5 was heated to form an isotropic liquid, which was filled into a cell having a thickness of about 2 μm and subjected to a polyimide rubbing alignment treatment. The Sc'' phase was then oriented by slowly cooling to room temperature. When we applied a rectangular wave with an electric field strength of 10 V F-F/μm to this cell and measured its electro-optical response speed, we found that it was 110 μm at 25°C.
High-speed response time of seconds was confirmed. The spontaneous polarization at this time was as large as 3.8 nC/cm'', and the tilt angle was 25°.

〔Effect of the invention〕

The compound represented by the general formula (I) of the present invention can be used as a chiral dopant to produce a large amount of energy even when added in a small amount, when it is mixed into a parent liquid crystal composition exhibiting an Sc phase to prepare an Sc'' liquid crystal composition. It can induce spontaneous polarization and enable high-speed response.

Further, it is possible to obtain both a compound with a relatively large helical pitch that makes it easy to adjust the helical pitch of the N@ phase, and a compound with a small helical pitch that is used for adjusting the helical pitch.

Further, the optically active compound represented by the general formula (I) of the present invention can be easily manufactured industrially, is colorless, and has excellent chemical stability against water, light, heat, etc., and is therefore practical.

Furthermore, the liquid crystal material comprising the ferroelectric liquid crystal composition of the present invention can achieve a high-speed response of about 100 μsec, and is extremely useful as a light switching element for display.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 represents an optically active alkyl group having 4 to 12 carbon atoms, and R^2 represents the number of carbon atoms. 2 to 10 alkyl groups, A ring represents a 1,4-phenylene group or 2-fluoro-1,4-phenylene group, m and n each independently represent 0 or 1, Y is -CH_2O - or -OCH_2-). 2. The compound according to claim 1, wherein the group represented by the general formula ▲ includes a numerical formula, a chemical formula, a table, etc. ▼ is an optically active group having the (S) configuration or the (R) configuration. 3. Claim 2, wherein R^1 is an optically active group represented by the general formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^3 represents an alkyl group having 2 to 10 carbon atoms.) Compounds described. 4. The absolute configuration of each of the two asymmetric carbon atoms in the molecule is (
4. The compound according to claim 3, which is a combination of the S) configuration and the (R) configuration, or a combination of the (R) configuration and the (S) configuration. 5. R^1 is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^4 represents an alkyl group having 2 to 6 carbon atoms, and k represents an integer from 1 to 4.) 3. The compound according to claim 2, which is an optically active group represented by: 6, A ring is a 1,4-phenylene group, and Y is -C
5. The compound according to claim 2, 3 or 4, which is H_2O-. 7. A liquid crystal composition containing the compound according to claim 1, 2, 3, 4, 5 or 6. 8. The compound according to claim 7, which exhibits a ferroelectric chiral smectic phase. 9. A liquid crystal display element using the liquid crystal composition according to claim 8.