JP2010030997A - Optically responsive chiral compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optically responsive chiral compound. <P>SOLUTION: The optically responsive chiral compound is represented by general formula (1). A nematic liquid crystal mixture containing this optically responsive chiral compound is also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel optically active chiral compound useful as an additive for a light-responsive liquid crystal display material such as an optical element and a light-optical switching element, and a liquid crystal display material containing the same.

  Liquid crystal compounds are currently used as display media due to their fluidity, optical anisotropy, and molecular alignment responsiveness to electric fields. Nematic liquid crystal or twisted liquid crystal is used as an element that acts as a shutter that controls the light transmittance with an electric field (Patent Document 1).

  In order to perform color display, red, green, and blue color filters are provided in front of each liquid crystal element, and the liquid crystal itself does not control color information.

  On the other hand, the color of the liquid crystal itself has been known for a long time (Non-Patent Document 1). Chiral nematic (cholesteric liquid crystal). A chiral nematic liquid crystal contains an optically active site in the liquid crystal molecular skeleton or as an additive, and as a result, exhibits a supramolecular structure in which the liquid crystal molecules draw a helix in the liquid crystal state (the molecular arrangement has a helical structure).

  Because of this helical supermolecular structure, one circularly polarized component of light having a wavelength centered on the product Pn of the helical period P and the average refractive index n of the substance is reflected in a direction parallel to the helical axis. To do. If Pn corresponds to the wavelength of visible light, light of a certain wavelength in visible light (white light) is reflected, so that it looks colored.

  The color of reflection that looks like this is sometimes referred to as a reflection color. Since the reflected color of some chiral nematic liquid crystals changes with temperature, chiral nematic liquid crystals have been used as thermometers that display temperature by color and materials that measure the surface temperature of substances (Non-Patent Document 2). .

  On the other hand, an attempt has been made to apply the reflected color of chiral nematic liquid crystal to color display (Patent Document 2). The direction of the helical axis of the chiral nematic liquid crystal is controlled by an electric field, and the reflected color can be seen when the helical axis is perpendicular to the substrate, and the reflected color cannot be seen when parallel. Display is possible.

By adding a polymer to the chiral nematic liquid crystal, the above two states can be kept stable (bistable) even after the electric field is removed (Non-patent Document 3).
Also known is a chiral nematic liquid crystal that can change the reflection color by temperature and light and can temporarily fix the reflection color by rapid cooling (Non-Patent Documents 4 and 5).

  It has also been proposed that this can be used as a rewritable full-color display medium. It is important as a color display medium to freely change the reflected color of a chiral nematic liquid crystal by a photochemical reaction. The reason is that light can be applied in a non-contact manner through a transparent medium (air or a transparent substrate), and therefore it is not necessary to provide electrodes in contact as in the case of control by an electric field.

  As one method for realizing a chiral nematic liquid crystal that responds to light, it is known to make the chiral additive added to the nematic liquid crystal light-responsive by molecular modification.

  The helical period of a chiral nematic liquid crystal consisting of a mixture of a nematic liquid crystal and a chiral additive is determined by the physical property value of the compound called the twisting force of the chiral additive and the amount added, so that the molecular structure of the chiral additive is determined by photoreaction. If reversible, the torsional force changes, and as a result, the reflected color can be reversibly controlled.

  As photoresponsive chiral additives that can be used in such a technique, ethylene derivatives, fulgide derivatives, and azobenzene derivatives are known (Non-Patent Document 6).

  The performance required for this photoresponsive chiral additive is that the original torsional force is large, the change in torsional force before and after light irradiation is large, and that the torsional force can be reversibly changed simply by changing the wavelength of light. It can be done.

  However, none of the conventionally known photoresponsive chiral additives satisfy all of the above, and only realize a change between specific colors in the visible range, or a reversible change is only a photoreaction. However, there is a problem that a second additive having no photoresponsiveness is necessary to compensate for a low torsional force.

Japanese Patent Publication No.51-13666 Japanese Patent Publication No.43-390

F. Reinitzer, Monatsch. Chem., 1889, 9, 421. J. L. Fergason, Appl. Phys., 1968, 7, 1729. J. L. West, R. B. Akins, J. Francl, J. W. Doane, Appl. Phys. Lett., 1993, 63, 1471. N. Tamaoki, A. Parfenov, A. Masaki, H. Matsuda, Adv. Mater., 1997, 9, 1102. N. Tamaoki, S. Song, M. Moriyama, H. Matsuda, Adv. Mater., 2000, 12, 94. N. Tamaoki, Adv. Mater., 2001, 13, 1135.

  The present invention has been made to overcome the problems of the prior art as described above, and is a twist for realizing a photoresponsive chiral nematic liquid crystal capable of controlling the reflected color in the entire visible range with only light. A novel photoresponsive chiral compound that has a large force, has a large change in torsional force before and after light irradiation, and can reversibly change the torsional force simply by changing the wavelength of light, and this compound as a chiral additive An object is to provide a liquid crystal display material.

That is, this application provides the following invention.
<1> An optically responsive chiral compound represented by the following general formula (1).
(In the formula, X and Y are divalent organic groups; Z contains an aromatic ring and has a C2 axis of symmetry in a direction perpendicular to the π-conjugated plane of the aromatic ring, but any plane containing that axis is a plane of symmetry. Z represents a group that is sufficiently bulky that no rotational movement of 360 degrees or more about the axis bonded to X and Y occurs due to steric collision with the azobenzene moiety)
<2> An optically responsive chiral compound represented by the following general formula (1A).
(Wherein, X _{1 is, -CH 2 -CH 2 -O -,} - O-CH 2 -CH 2 -, - CH 2 -O-CH 2 - or - CH ₂ -CH ₂ -CH ₂ - shows the )
<3> A nematic liquid crystal mixture containing the photoresponsive chiral compound according to <1> or <2>.
<4> An optical liquid crystal element using the nematic liquid crystal mixture according to <3> as a display material.

  The photoresponsive chiral compound represented by the general formula (1) according to the present invention has a large twisting force, a large change in torsional force before and after light irradiation, and a reversible twisting force by simply changing the wavelength of light. Can be changed. Therefore, a nematic liquid crystal mixture containing this as a chiral additive can be used as a rewritable full-color display medium because it can control the reflected color in the entire visible range with only light.

Reflection spectrum of the liquid crystal display material of the present invention

  The photoresponsive chiral compound of the present invention is represented by the general formula (1). This compound does not have structural features such as central asymmetry, axial asymmetry, and helical asymmetry, but is optically active due to surface asymmetry.

  The requirement for exhibiting plane asymmetry is that in general formula (1), Z is a divalent organic group having a plane structure and has a C2 symmetry axis in a direction perpendicular to the plane, but includes that axis. Two planes are that no plane becomes a symmetric plane, and Z is sufficiently bulky that a rotational movement of 360 degrees or more around the axis connecting X and Y does not occur due to a three-dimensional collision with the azobenzene moiety. It is necessary to satisfy the conditions simultaneously.

For example, X and Y that connect Z and the azobenzene moiety have more than 3 atoms directly related to the distance connecting Z and azobenzene, for example, -O-CH ₂ -CH ₂ -O- However, since the rotation of 360 degrees or more about the axis connecting Z and X is possible, the molecule does not become optically active. In addition, when the number of atoms directly related to the distance connecting Z and azobenzene is less than 3, the steric repulsion between azobenzene and Z is large in order to establish a ring structure, which makes synthesis difficult. The number of atoms of Y and Y is preferably 3 respectively.

The specific structure is not particularly limited, but for ease of synthesis, for example, —CH ₂ —CH ₂ —O— or —O—CH ₂ —CH ₂ — from the azobenzene side toward the naphthalene moiety. , -CH ₂ -O-CH ₂ - or - CH ₂ -CH ₂ -CH ₂ -, etc. are preferable. In particular, —CH ₂ —CH ₂ —O— is desirable in view of the availability of synthetic raw materials. The bonding position of X or Y and azobenzene may be any of ortho, meta, and para, but meta is more preferable because of ease of synthesis and difficulty in rotational movement of Z.

  As the structure of Z, for example, 1,5-substituted-naphthalene, 2,6-substituted-naphthalene, 2,5-dialkyl-1,4-substituted-benzene (as a structure satisfying the requirement of plane asymmetry of the whole molecule ( The alkyl group preferably has 1 to 5 carbon atoms), 2,5-dialkoxy-1,4-substituted-benzene (the alkoxy group preferably has 1 to 5 carbon atoms), and the like. However, it is not limited to this. Among these, 1,5-substituted naphthalene is a desirable structure because of the availability of synthetic raw materials.

  The reaction and action of the photoresponsive chiral compound of the present invention will be described by taking (S) E-1 in the following diagram as an example. (S) E-1 is in an enantiomeric relationship with (R) E-1. However, the racemization reaction (conversion between (S) E-1 and (R) E-1) does not occur because it is thermally stable enough. In addition, (S) E-1 has a geometric isomerism (cis-trans isomerism) relationship with (S) Z-1. Between these, conversion is possible by photochemical reaction or thermal reaction with ultraviolet rays or visible light. (R) E-1 has the same relationship as (R) Z-1. Therefore, (S) E-1 or (R) E-1 has inherent chirality due to surface asymmetry and inherent torsional force in nematic liquid crystals, and is reversibly generated by photoreaction (S) Z- 1 or (R) Z-1 exhibits different chirality and torsional force from (S) E-1 and (R) E-1. As a result, the torsional force can be reversibly changed by photoreaction.

In order to obtain the photoresponsive chiral compound of the present invention, as described later, for example, the corresponding dinitro compound can be obtained by reduction with a reducing agent such as lithium aluminum hydride.
Since the obtained compound is a mixture of two enantiomers, it is isolated as one pure enantiomer by a method such as separation using a chiral column to make a photoresponsive chiral additive.

In order to prepare a photoresponsive chiral nematic liquid crystal using this photoresponsive chiral compound, the photoresponsive chiral compound and nematic liquid crystal may be mixed. Examples of nematic liquid crystals that can be used include, but are not limited to, cyanobiphenyl nematic liquid crystals, cyanophenylcyclohexyl nematic liquid crystals, and ester nematic liquid crystals.
The concentration of the photoresponsive chiral additive in the nematic liquid crystal varies depending on the structure of each substance. Generally, it is used in the range of 0.01% to 30% by weight. More desirably, it is used in the range of 0.5 to 15% by weight. If the concentration of the photoresponsive chiral additive is lower than this range, the reflection wavelength of light becomes longer than that of visible light. If the concentration is higher than this range, the photoresponsive chiral additive is precipitated from the nematic liquid crystal. Or the reflected wavelength of light will be shorter than visible light.

  Since the nematic liquid crystal mixture containing the photoresponsive chiral compound as an additive can control the reflected color in the entire visible range with only light, it is useful as a rewritable full-color display medium.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
(Synthesis of photoresponsive chiral compounds)
In this example, photoresponsive chiral additive example 1 was synthesized according to the following process.

First, 1.3 ml of triethylamine was dissolved in 3 ml of methylene chloride, and added dropwise at 0-5 ° C. to a solution of 2.5 g of 3-nitrophenethyl alcohol and 2.52 g of p-toluenesulfonyl chloride in 15 ml of methylene chloride. The mixture was slowly warmed to room temperature with stirring, and stirring was continued overnight. After adding 4 ml of 1N hydrochloric acid, the organic layer was separated using a separating funnel, and the organic layer was washed with an aqueous NaHCO 3 solution and brine. The solution was dried and concentrated to give the crude product. The resulting crude product was further purified by column chromatography using a hexane-ethyl acetate mixture to obtain Compound 1. Yield 3.2 g, 83% yield.
¹ H NMR (300 MHz, CDCl ₃ ): δ8.07 (dd, 1H, J = 1.7, 7.8Hz), 7.90 (s, 1H), 7.65 (d, 2H, J = 8.3Hz), 7.51-7.42 ( m, 2H), 7.28-7.25 (m, 2H), 4.29 (t, 2H, J = 6.4Hz), 3.06 (t, 2H, J = 6.4Hz), 2.42 (s, 3H).

Next, Compound 1 (16.3 g), 2.0 g of 1,5-dihydroxynaphthalene and 8.8 g of potassium carbonate were dissolved in 25 ml of dry dimethylformamide, heated to 60 ° C. and stirred for 12 hours. The reaction mixture was added into 150 ml of water to give the crude product as a brown precipitate. The crude product was washed with ethyl acetate to give pure compound 2 as a white solid. Yield 4.2 g, 73% yield.
¹ H NMR (300 MHz, DMSO-d ₆ ): δ8.31 (s, 2H), 8.10 (d, 2H, J = 8.1 Hz), 7.89 (d, 2H, J = 7.5 Hz), 7.65-7.60 ( m, 4H), 7.33 (t, 2H, J = 7.9Hz), 6.99 (d, 2H, J = 7.7Hz), 4.40 (t, 4H, J = 6.1Hz), 3.32 (t, 4H, J = 6.2 Hz); MALDI-TOF MS (M + H) calcd forC ₂₆ H ₂₃ N ₂ O ₆ : 459.52, found: 459.59

Finally, Compound 2 (2.0 g) was dissolved in 300 ml of dry tetrahydrofuran, and the solution was added dropwise over 6 hours to a solution of 1.7 g of lithium aluminum hydride dissolved in 100 ml of dry tetrahydrofuran under an argon atmosphere. The reaction mixture was dry-distilled when Compound 2 was added dropwise, and further stirred at room temperature for 12 hours. After the reaction mixture was cooled with ice water, water was carefully added. The precipitate was filtered off and the solvent was removed under reduced pressure. The remaining organic solid was dissolved in ethyl acetate, washed with water, and dried over anhydrous magnesium sulfate. After removing the solvent under reduced pressure, the residue was purified by silica gel chromatography using hexane-ethyl acetate (4: 1) as a developing solvent to obtain the target compound 3 as an orange solid. Yield 10.7 mg, 1% yield.
¹ H NMR (300 MHz, CDCl ₃ ): δ7.67 (d, 2H, J = 8.3Hz), 7.55 (d, 2H, J = 7.8Hz), 7.35 (t, 2H, J = 7.6Hz), 7.23 (d, 2H, J = 7.5Hz), 7.05 (t, 2H, J = 8.1Hz), 6.79 (s, 2H), 6.60 (d, 2H, J = 7.7Hz), 4.76 (dt, 2H, J = 14.6, 3.6 Hz), 4.60 (dt, 2H, J = 12.5, 3.8 Hz), 3.21 (dd, 4H, J = 11.5, 3.2 Hz); ¹³ C NMR (75 MHz, CDCl ₃ ): δ154.1, 152.3 , 140.4, 130.6, 128.9, 127.9, 125.6, 125.0, 120.0, 114.6, 107.7, 68.4, 35.9; ESIMS m / z 395.2 (M + H +), 417.2 (M + Na +).
Since this synthesized compound 3 is a mixture of two enantiomers, a pure photoresponsive chiral compound is obtained by splitting a mixed solvent of ethyl acetate / hexane as a developing solvent using a chiral column (Chiral Pack IA manufactured by Daicel Chemical Industries). Additives 4R and 4S were obtained.

(Measurement of torsional force of photoresponsive chiral compounds)
In the photoresponsive cholesteric liquid crystal, compound 4R, which is a photoresponsive chiral additive, is added to nematic liquid crystal at a constant weight%, and a small amount of methylene chloride is added to dissolve in a sample tube, and the solvent is removed under reduced pressure. I got it. The obtained photoresponsive cholesteric liquid crystal was added to the wedge cell by capillary effect at room temperature, and the distance between the observed Cano lines was measured to estimate the cholesteric helical pitch. The torsional force of the photoresponsive chiral additive was calculated from the slope of the region where the concentration of the photoresponsive chiral additive and the reciprocal of the cholesteric helical pitch are linearly related. As a result, it was 43, 40, and 16 μm −1 in each nematic liquid crystal 5CB (manufactured by Tokyo Chemical Industry), ZLI-1132 (manufactured by MERK), and DON-103 (manufactured by Dainippon Ink, Inc.). From the same measurement, the torsional force after irradiating 366 nm light to the light steady state changed to 36, 28, and 19 μm−1 in 5CB, ZLI-1132, and DON-103, respectively. Thereafter, the torsional force was measured after further irradiation with 436 nm light to obtain a light steady state. From the same measurement, it changed to 40, 36, and 17 μm-1 in 5CB, ZLI-1132, and DON-103, respectively. did.

Example 2
(Production of liquid crystal display materials)
Next, a photoresponsive cholesteric liquid crystal in which 12 wt% of the compound 4R was added to ZLI-1132 was sandwiched between two glass plates coated with polyimide as an alignment film with a spacing of 5 microns. The reflection spectrum of the obtained thin film before and after 366 nm light (UV) irradiation was measured. From the light steady state after irradiation for 120 seconds, 436 nm light (Vis) was irradiated for 30 seconds for 120 seconds, and the reflection spectrum was measured. The obtained reflection spectrum is shown in FIG.

Example 3
Compound 9 was synthesized by the following method using 1,5-diaminonaphthalene (compound 4) and 3-nitrophenol (compound 7) as starting materials.

Synthesis scheme

Compound 5: Concentrated sulfuric acid solution (12.5 mL) of sodium nitrite (1.5 g, 0.022 mol) and acetic acid solution (12.5 mL) of 1,5-diaminonaphthalene (4) (1.5 g, 0.0095 mol) at 0 ° C It was dripped. The mixed solution was stirred for 15 minutes, ice (15 g) and urea (0.125 g) were added, potassium iodide (50 g, 0.3 mol) aqueous solution (50 ml) was added, and the mixture was stirred overnight under reduced pressure. The solid obtained by filtration was extracted with dichloromethane after drying. The whole extract was refluxed in the presence of activated carbon, and finally purified by silica gel column chromatography using hexane / dichloromethane (2: 1) as an elution solvent to obtain pale yellow acicular compound 5. Yield (2.5 g, 69%).
¹ H NMR (300 MHz, CDCl ₃ ): δ7.26 (t, 2H, J = 7.5 Hz), 8.13 (d, 4H, J = 6.9 Hz), MALDI-TOF MS (M + H ⁺ ) calcd for C ₁₀ H ₆ I ₂ : 379.96, found: 379.57.

Compound 6: 36 mL ether suspension of 1,5-diiodonaphthalene (2.28 g, 0.006 mol) was cooled to -78 ° C, and 15 mL of n-butyllithium solution (1.6 M hexane solution, 0.024 mol) was added. It was. After stirring this light pink suspension for 1 hour, 268.8 mg (0.003 mol) of copper (I) cyanide was added, and stirring was further continued at -55 to -65 ° C for 45 minutes. During this time, the suspension turned yellow. 150 ml of ethylene oxide (1 M ether solution, 0.150 mol) was added at once, and the mixture was stirred overnight at room temperature. 10% sulfuric acid was poured into this mixture in a ventilator, and after filtration, extracted with dichloromethane. A crude solid sample dehydrated with anhydrous sodium sulfate and concentrated under reduced pressure was purified by silica gel chromatography using ethyl acetate / dichloromethane (1: 1) as an eluent to obtain white solid 6. Yield (0.57 g, 44%).
¹ H NMR (300 MHz, CDCl ₃ ): δ 3.37 (t, 4H, J = 6.8 Hz), 4.01 (t, 4H, J = 6.33 Hz), 7.45 (m, 4H), 8.00 (d, 2H, J = 7.95 Hz). MALDI-TOF MS (M + H ⁺ ) calcd for C ₁₄ H ₁₆ O ₂ : 216.27, found: 216.41.

Compound 8: Diisopropyl azodicarboxylate (40% toluene solution, 5 mL, 9.9 mmol) is added dropwise, compound 6 (0.713 g, 3.3 mmol), 3-nitrophenol (1.146 g, 8.2 mmol), triphenylphosphine ( 2.6 g, 9.9 mmol) was added to a dehydrated THF solution (25 mL) at 0 ° C. The solution was stirred overnight at room temperature. A crude product sample of a brown precipitate obtained by adding excess water (150 mL) to the reaction solution was washed with ethyl acetate, and then purified compound 8 was obtained as a white solid. Yield (0.8 g, 53%).
¹ H NMR (300 MHz, DMSO-d ₆ ): δ3.57 (t, 4H, J = 6.8 Hz), 4.44 (t, 4H, J = 6.8 Hz), 7.39 (d, 2H, J = 5.8 Hz) , 7.52-7.57 (m, 4H), 7.57 (s, 2H), 7.67 (t, 2H, J = 2.3 Hz), 7.78 (d, 2H, J = 6.9 Hz), 8.11 (t, 2H, J = 4.8 ); MALDI-TOF MS (M + H ⁺ ) calcd for C ₂₆ H ₂₂ N ₂ O ₆ : 458.46, found: 481.67 (M + Na ⁺ ).

Compound 9: A dehydrated THF solution (300 mL) of Compound 8 (0.5 g, 1.09 mmol) is added dropwise to a dehydrated THF solution (100 mL) of LiAlH ₄ (0.42 g, 10.9 mol) over 4 hours in an argon atmosphere. Added one by one. When the dinitro compound solution was added dropwise, the reaction solution was refluxed and then stirred overnight at room temperature. The reaction solution was quenched by careful addition of water while cooling in an ice bath. Insolubles were filtered off, and the filtrate was concentrated under reduced pressure. The orange residue solid was dissolved in dichloromethane, washed with water and then dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the residue was purified by silica gel column chromatography using hexane and ethyl acetate (4: 1) as an eluent to give an orange solid 9. Yield 30 mg (7%).
¹ H NMR (300 MHz, CD ₂ Cl ₂ ): δ3.44 (dt, 2H, J = 4.7, 4.7 Hz); 3.77 (tt, 2H, J = 3.2, 3.2 Hz); 4.62 (tt, 2H, J = 4.5, 4.5 Hz); 4.88 (dd, 2H, J = 3.2, 7.9 Hz); 6.11 (d, 2H, J = 1.7 Hz); 7.0 (dd, 2H, J = 4.7, 4.5 Hz), 7.29-7.38 (m, 8H), 7.94 (dd, 2H, J = 2.9, 2.8 Hz); ¹³ C NMR (75 MHz, CD ₂ Cl ₂ ): δ33.0, 70.1, 108.8, 114.2, 120.0, 122.6, 125.7, 127.2 , 129.4, 132.3, 136.9, 152.9, 159.6; ESIMS m / z 395.2 (M + H ⁺ ), 417.2 (M + Na ⁺ ).

The torsional force of this compound was measured in the same manner as in Example 1. Compound 9 of the optical divided enantiomer in ZLI-1132, 6.9 [mu] m ^-1 before irradiation, 7.9 .mu.m ^-1 after UV irradiation, showed torsional force of 7.1 [mu] m ^-1 after irradiation with visible light.

Example 4
Compound 10 was synthesized by the following method.

In a suspension of 198 mg of powdered potassium hydroxide in 10 ml of dimethyl sulfoxide, a solution of 121 mg of azobenzene-3,3′-dimethanol and 157 mg of 1,5-bis (bromomethyl) naphthalene in 10 ml of tetrahydrofuran was prepared at 50 ° C. The solution was slowly added dropwise with stirring. After dropping, the mixture was stirred for 30 minutes, then transferred to a separatory funnel, ethyl acetate was added, and the mixture was washed 3 times with water. The organic layer was dried over anhydrous magnesium sulfate and concentrated, and then purified by silica gel column chromatography using dichloromethane as an eluent. Yield 19.7 mg, 10% yield.
¹ H NMR (300 MHz, CDCl ₃ ): δ8.18 (br d, 2H, J = 8.0 Hz), 7.55 (br d, 2H, J = 7.8 Hz), 7.44 (br d, 2H, J = 6.9 Hz) ), 7.38 (t, 2H, J = 7.6 Hz), 7.32 (t, 2H, J = 7.7 Hz), 7.21 (br d, 2H, J = 7.5 Hz), 6.77 (s, 2H), 5.62 (d, 2H, J = 13.2 Hz), 5.04 (d, 2H, J = 13.8 Hz), 4.86 (d, 2H, J = 13.8 Hz), 4.79 (d, 2H, J = 13.2 Hz); ¹³ C NMR (75 MHz , CDCl ₃ ): 152.4, 140.4, 135.3, 132.5, 128.4, 128.0, 127.1, 125.7, 125.2, 124.1, 119.8, 73.4, 72.8; ESIMS m / z 395.2 (M + H ⁺ ), 417.2 (M + Na ⁺ ) .

The torsional force of this compound was measured in the same manner as in Example 1. Compound 10 of the optical divided enantiomer in ZLI-1132, 27 [mu] m ^-1 before irradiation, 20 [mu] m ^-1 after UV irradiation, showed torsional force of 26 .mu.m ^-1 after irradiation with visible light.

Example 5
Compound 11 was synthesized by the following method.

12.36 mmol of diisopropyl azodicarboxylate in a nitrogen atmosphere with a THF solution of triphenylphosphine (12.36 mmol), 2-phenethyl alcohol (9.88 mmol), 2,5-dimethoxy-1,4-dihydroquinone (4.12 mmol) 5 mL) was added dropwise at 0 ° C. Thereafter, the mixture was vigorously stirred at room temperature for 12 hours. When 150 mL of water was added, the crude product precipitated. This was washed with ethyl acetate to obtain a pure dinitro compound. The dinitro compound 1.07 mmol obtained was dissolved in dry THF (250 mL), was added dropwise to LiAlH ₄ (10.7 mmol) in dry THF solution (100 mL) over a period of 6 hours. During the addition, the solvent was heated to continue to reflux. After the reaction for 12 hours, the mixture was cooled in an ice bath and water was carefully added. After removing the solvent under reduced pressure, the residue was purified by silica gel column chromatography using dichloromethane as an eluent to obtain the target compound 11. Yield 5.27 mg.
¹ H NMR (400 MHz, CDCl ₃ ): δ 7.55 (d, 2H, J = 8.35 Hz), 7.46 (t, 2H, J = 14.6 Hz), 7.21-7.25 (m, 2H), 7.13 (d, 2H , J = 7.6 Hz), 6.0 (s, 2H), 4.69 (m, 4H), 4.18-3.31 (m, 4H) 3.18 (s, 6H). ESI MS m / z = 427.1 (M + Na ⁺ ) Exact Mass: 404.2.

The torsional force of this compound was measured in the same manner as in Example 1. Compound 11 of the optical divided enantiomer in ZLI-1132, 5.5 [mu] m ^-1 before irradiation, 3.4 .mu.m ^-1 after UV irradiation, showed torsional force of 5.5 [mu] m ^-1 after irradiation with visible light.

Claims (4)

An optically responsive chiral compound represented by the following general formula (1).
(Wherein X and Y are divalent organic groups; Z contains an aromatic ring and has a C2 axis of symmetry in a direction perpendicular to the π-conjugated plane of the aromatic ring, but any plane containing that axis is a plane of symmetry. Z represents a group that is sufficiently bulky that no rotational movement of 360 degrees or more about the axis bonded to X and Y occurs due to steric collision with the azobenzene moiety) An optically responsive chiral compound represented by the general formula (1A).
(Wherein, X _{1 is, -CH 2 -CH 2 -O -,} - O-CH 2 -CH 2 -, - CH 2 -O-CH 2 - or - CH ₂ -CH ₂ -CH ₂ - shows the )   A nematic liquid crystal mixture containing the photoresponsive chiral compound according to claim 1.   An optical liquid crystal element using the nematic liquid crystal mixture according to claim 3 as a display material.