JPH1060424A - Photochromic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material exhibiting large variation in optical rotation by the irradiation with light of a long wavelength range to enable the non-destructive read-out of a record by the change in the optical. rotation and suitable as an optical recording material by using an optically active compound having plural photochromic organic groups. SOLUTION: This photochromic material is composed of an optically active compound having plural organic groups exhibiting photochromism. The organic group exhibiting photochromism is preferably benzothiophene group and an organic group having phenylthienyl skeleton. The plural organic groups of the optically active compound are preferably same to each other. The compound of the formula is a preferable example of the optically active compound. The optically active compound is preferably produced by reacting a diarylethene compound having a halogen and a reactive group such as formyl with a (1R,2 R)-(-)-transhexane compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photochromic material that produces a change in optical rotation upon irradiation with light. More specifically, the present invention relates to a photochromic material suitable as an optical recording medium, capable of reading out information recorded using the above-mentioned optical rotation change without destroying the information.

[0002]

2. Description of the Related Art A photochromic material is an organic group which causes a reaction of reversibly generating two isomers having different states by the action of light (hereinafter, also simply referred to as "photoisomerization reaction"), that is, a photochromic material. Refers to a material including a compound having an organic group exhibiting properties (hereinafter, also simply referred to as “photochromic compound”). Photochromic compounds are
Since the absorption spectrum (that is, the absorbance at a specific wavelength) changes in accordance with the reversible structural change due to the photoisomerization reaction, research on applying photochromic materials to optical recording has been advanced.

When a photochromic material is used as an optical recording material, information is recorded (optical recording) by irradiating a specific position (spot) of the material with light and selectively forming a photochromic compound present at the spot. It is done by changing. Since the above-mentioned structural change does not occur in the spot where the light is not irradiated, information is recorded as a pattern of the spot where the structural change occurs and the spot where the structural change does not occur. In the photochromic compound, the physical properties change with the structural change, and thus the recorded information can be read by reading the pattern of the change in the physical properties. It is well known that the photochromic compound changes the light absorption spectrum due to the structural change, and the optically recorded information can be read by detecting a change in absorbance. However, in order to detect a change in absorbance, it is necessary to irradiate light of a wavelength corresponding to the absorption position, and information recorded optically is changed by this light irradiation (at the time of reading) (record destruction). Problems arise. Usually, a method of performing reading by irradiating weak light is adopted (T. Tsujioka et.al., Jpn. J. Appl. Phys., 34 , 64).
39 (1995)), since the photoisomerization reaction of a photochromic compound proceeds in proportion to the amount of light absorbed, the photoisomerization reaction (reverse reaction at the time of optical recording) occurs when reading is continued for a long time even when irradiated with weak light. Induced, the occurrence of the recording destruction was unavoidable.

[0004]

Therefore, in order to use a photochromic material as a reliable optical recording, it is important to develop a reading method that does not cause recording destruction. The present inventors considered that the above problem could be solved if, for example, recorded information could be read out as a change in physical quantity other than absorbance by a method that does not cause photoisomerization reaction. Then, attention was paid to “optical rotation that can be detected by irradiation with light in a long wavelength region that does not induce the photoisomerization reaction” as the physical quantity.

Conventionally, it has been known that when an asymmetric carbon is introduced into a photochromic compound, the optical rotation of the compound is changed by the photoisomerization reaction. That is, Lau (H.Ra
u) et al. report that the optical rotation changes when light is irradiated to a photochromic compound into which an asymmetric carbon has been introduced (Chem. Reviews (Chem. Rev.), 1983, 83, 535). page). However, the amount of change in the optical rotation with respect to the sodium D line (589.29 nm) at this time is very small, not more than 100 degrees as represented by the specific optical rotation ([α]), and induces a structural change of the photochromic compound. The amount of change in specific rotation with respect to light having a longer wavelength was further reduced so as to exceed 600 nm. Therefore, even when reading was performed by optical rotation using the photochromic compound disclosed in the above-mentioned document, reading could not be performed accurately without causing recording destruction.

That is, an object of the present invention is to develop a method for inducing a large optical rotation change with respect to light in a long wavelength region that does not cause a structural change of a photochromic compound. An object of the present invention is to create a photochromic material capable of performing nondestructive readout by detecting a degree.

[0007]

Means for Solving the Problems The present inventors have intensively studied a method for inducing a large optical rotation change in a photochromic compound. As a result, in the optically active compound having a plurality of organic groups exhibiting photochromic properties in the molecule, the present inventors have obtained a new finding that the optical rotation for light in a long wavelength region is significantly changed due to the photoisomerization reaction. It was completed.

That is, the present invention is a photochromic material comprising an optically active compound having a plurality of organic groups having photochromic properties in a molecule.

When the photochromic material of the present invention is irradiated with light, the amount of change in optical rotation with respect to light of 633 nm is:
The specific rotation ([α]) may exceed 1000 degrees,
The change in the optical rotation in the above-mentioned “conventional photochromic compound into which asymmetric carbon is introduced” is much larger than the change in the optical rotation.
Such a large change in optical rotation is obtained because, when the optically active compound used in the present invention is irradiated with light to cause a photoisomerization reaction, a plurality of photochromic groups present in the molecule are present. It is presumed that when at least two of them undergo structural changes, a certain type of exciton interaction is induced. Regarding the estimation, the present inventors, as shown in a reference example described later, when performing photoisomerization reaction by performing light irradiation on an optically active compound having two groups exhibiting photochromic properties, these organic groups It is confirmed by a circular dischroism spectrum (hereinafter, also simply referred to as "CD spectrum") measurement that a large change in optical rotation is obtained specifically in a long wavelength region when both of them undergo structural changes. doing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The photochromic material of the present invention comprises an optically active compound having a plurality of photochromic organic groups in the molecule.

It is essential that the compound used in the photochromic material of the present invention has an optically active (rotatory) site. Therefore, the optically active compound used in the present invention needs to have at least one asymmetric carbon in the molecule. When there is no asymmetric carbon in the molecule, the compound does not show optical activity (optical rotation) and cannot read optically recorded information by a change in optical rotation. The number and position of the asymmetric carbon contained in the optically active compound used in the present invention are not particularly limited as long as the compound exhibits optical activity.

The organic group having photochromic properties in the optically active compound used in the present invention is particularly an organic group which causes a photoisomerization reaction and causes a reversible structural change by the photoisomerization reaction. Although not limited, an organic group having a diarylethene structure is preferable.
Above all, the isomer has a 5-membered heterocyclic ring in the aryl moiety because of the high chemical and thermal stability of each isomer and the high conversion rate of the structure due to the photoisomerization reaction, and the high durability of the photoisomerization reaction repeated. An organic group having a diarylethene structure is preferable, and an organic group having a perfluorodiarylethene structure having a benzothiophene and phenylthienyl skeleton is particularly preferable. If the number of the organic groups having photochromic properties existing in the molecule of the optically active compound of the present invention is two or more per molecule, a large optical rotation change can be obtained by the photoisomerization reaction. At this time, the plurality of organic groups having photochromic properties contained in the optically active compound used in the present invention are desirably the same.

The method for producing the optically active compound used in the present invention is not particularly limited, but it can be suitably produced by the following method. That is, the optically active compound can be suitably produced by a method of bonding a polyvalent organic group having an asymmetric carbon and an organic group having the same valence as that of the organic group and exhibiting a monovalent photochromic property. it can. Here, the method of bonding each of the above groups is not particularly limited. For example, a halogen atom and a reactive group such as a formyl group, an alkylcarbonyl group, a carboxyl group, and an amino are bonded to each group by an ordinary method. To produce various reactive precursors, and reacting the obtained various reactive precursors appropriately according to a conventional method.

In the method, the polyvalent organic group having an asymmetric carbon and the organic group having photochromic properties are not particularly limited as long as they can synthesize a reactive precursor.
(1R, 2R)-as a polyvalent organic group having an asymmetric carbon
An optically active compound produced using a divalent organic group having a (-)-trans-diaminohexane structure and an organic group having a diarylethene structure as an organic group having photochromic properties is induced by a photoisomerization reaction. The “rotational change with respect to light in a long wavelength region” is particularly large and particularly suitable. Taking the compound as an example, the synthesis method will be described in detail below.

That is, the above compound has a diarylethene compound having a halogen atom and a reactive group such as a formyl group, an alkylcarbonyl group, a carboxyl group and an amino, and a (1R, 2R)-having a reactive group similar to the above.
The (-)-transhexane compound can be dissolved in the presence of a dehydrating agent such as magnesium sulfate and molecular sieves and / or a compound such as 1,2-dichloroethane and methanol in the presence of a hydrogen halide trapping agent such as triethylamine. It can be synthesized by reacting at room temperature to 180 ° C. using a solvent.

The optically active compound used in the present invention obtained by such a method can be used as it is as a photochromic material. However, the photochromic material can be appropriately dispersed in a suitable matrix. It is preferred to use The matrix material (base material) used at this time is not particularly limited as long as it does not inhibit the photoisomerization reaction of the optically active compound used in the present invention. It is preferable that the material can be dispersed in and can be shaped. Examples of such a base material include thermosetting resins such as ethylene glycol dimethacrylate and bisphenol A dimethacrylate, and thermoplastic resins such as polymethyl acrylate, polymethyl methacrylate, polythrylene, and polycarbonate, polypropylene, and polyethylene. . The method for dispersing the optically active compound used in the present invention in these base materials is not particularly limited,
For example, when the base material is a thermosetting resin, a method of dispersing the optically active compound in a monomer and then polymerizing and curing the same, and when the base material is a thermoplastic resin, the above-described optically A method in which the active compound is blended and melt-kneaded, or the like is appropriately employed. When the optically active compound used in the present invention is used by dispersing in the matrix, the concentration of the optically active compound in the matrix may be appropriately determined according to the type and combination of the base material and the optically active compound used. Good, but generally 100-3
It is in the range of 00,000 ppm. At this time, various known additives can be blended as long as the effects of the present invention are not impaired. Examples of such additives include singlet oxygen quenchers such as hindered phenol and hindered amine, and antioxidants such as phosphate esters and phosphite esters.

The photochromic material of the present invention changes its optical rotation greatly by irradiating light that induces a photoisomerization reaction. Therefore, a change in the structure of the optically active compound due to the light irradiation can be easily regarded as a change in optical rotation. And can be detected with high accuracy. In addition, the change in the optical rotation can be detected by irradiating light in a wavelength region that does not induce the photoisomerization reaction. Therefore, when the photochromic material of the present invention is used as an optical recording material, if the recorded information is read out by detecting the optical rotation, a photoisomerization reaction (a reverse reaction during optical recording) at the time of the detection can be prevented. And reading can be performed without causing record destruction.

For example, when the optically active compounds of Examples 1 and 2 described below are used as an optical recording material, the wavelength range of light that induces a structural change (photoisomerization reaction) of these compounds is shorter than 600 nm. In the wavelength region, a change in optical rotation can be detected by irradiating light of, for example, 633 nm. Therefore, optical recording and reading can be performed by the following methods. That is, these optically active compounds are dispersed in a polymer medium to form an optical recording film,
The entire surface is colored and initialized by irradiation with ultraviolet light (wavelength 313 nm). Then, an argon laser 52 was applied to the optical recording film.
Optical recording is performed by irradiating light of 9 nm. The recorded information is obtained by irradiating 633 nm light of a helium ion laser onto the optically recorded optical recording film to detect a change in the position of the optical rotation. Since the colored body has no absorption at 633 nm, a photoisomerization reaction does not occur, and thus nondestructive readout is achieved. Also,
To erase recorded information, the entire surface may be irradiated with ultraviolet light again.

As described above, in the optically active compound used in the present invention, a large optical rotation change is caused by a structural change of at least two of a plurality of photochromic groups present in the molecule of the optically active compound. Is induced. This means that the optical rotation has a nonlinearity in which a change in optical rotation is recognized only at a high light intensity, and a high contrast can be obtained.

[0020]

The optically active compound used in the present invention has a remarkable change in the optical rotation, particularly for light in a long wavelength region, by a photoisomerization reaction. Therefore, when the photochromic material of the present invention comprising the optically active compound is used as an optical recording material, it is possible to read recorded information without causing recording destruction by detecting the change in the optical rotation. .

[0021]

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

Example 1 In a 50 ml three-neck flask under a nitrogen atmosphere, 4- [3- [1- (2-methylbenzo [b] thien-3-yl) -hexafluorocyclopenten-2-yl] was used as a reaction reagent. -2,4-dimethylthien-5-yl] benzoic acid 101 mg (1.8 × 10 ⁻⁴ M), oxazalyl chloride 0.05 ml (6.0 × 10 ⁻⁴ M),
5 ml of 1,2-dichloroethane as a solvent and 0.025 m of triethylamine as a hydrogen chloride trapping agent
1 (1.8 × 10 ⁻⁴ M) and stirred at room temperature for 1 hour.
The mixture was heated and stirred at 60 ° C. for 1 hour. Next, after distilling off the solvent, 5 ml of 1,2-dichloroethane and (1R, 2R)-
10 mg of (-)-1,2-diaminocyclohexane (9
× 10 ^-5 M) and stirred at room temperature for 6 hours. afterwards,
An aqueous solution of sodium carbonate was added, extracted with chloroform, dried over anhydrous magnesium sulfate, separated and purified by thin layer chromatography (TLC), and 50 mg of a compound represented by the following formula (hereinafter, also referred to as “compound 1”) was isolated and collected. Obtained at a rate of 47%.

[0023]

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(In the formula, the symbol * indicates the position of the asymmetric carbon.) The structure of Compound 1 was determined by proton NMR (
¹ H NMR) and elemental analysis. The results of these analyzes of Compound 1 are as follows.

¹ H NMR analysis result (using CDCl ₃ solvent): δ
1.23-1.24 (m, 26H, CH ₃ × 6, CH ₂ × 4), 4.04 (br-s, 2H, CH
N), 6.92-7.38 (m, 8H, aromatic), 7.52-7.73 (m, 8H, aromatic)
matic) Elemental analysis: C 61.17 (% by weight); H 4.22 (% by weight); N 2.44 (% by weight). The theoretical value calculated from the composition formula of C ₆₀ H ₄₆ F ₁₂ N ₂ O ₂ S ₄ is C 60.90 (% by weight);
92 (% by weight); N 2.37 (% by weight).

Compound 1 was dissolved in hexane and irradiated with ultraviolet light (wavelength 313 nm), and the specific rotation [α] at 633 nm was measured. As a result, a value of 900 ° was obtained.

Example 2 Under a nitrogen atmosphere, 1- (2-
Methylbenzo [b] thien-3-yl) -2- [5-
(4-formyl) phenyl-2,4-dimethylthiene-
3-yl] hexafluorocyclopentene 200mg
(3.73 × 10 ⁻⁴ M), 6 ml of methanol, (1
21.3 mg (1.97 × 10 ⁻⁴ M) of R, 2R)-(−)-1,2-diaminocyclohexane and 80 mg of anhydrous magnesium sulfate were added, and the mixture was stirred at room temperature for 12 hours. Thereafter, the reaction solution was filtered and separated and purified by gel permeation chromatography (GPC) to obtain 210 mg of a compound represented by the following formula (hereinafter, also referred to as “compound 2”) in an isolated yield of 98%. .

[0028]

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(In the formula, the symbol * indicates the position of the asymmetric carbon.) The structure of Compound 2 was determined by ¹ H NMR and elemental analysis. The results of these analyzes of Compound 2 are as follows.

¹ H NMR analysis results (using CDCl ₃ solvent):
_{δ1.23-1.24 (m, 26H, CH 3} × 6, CH 2 × 4), 3.40 (br-s, 2H, CH
N), 7.14-7.38 (m, 8H, aromatic), 7.51-7.73 (m, 8H, aromatic)
matic), 8.16 (br-s, 2H, olefinic) Elemental analysis: C 62.62 (% by weight); H 4.28 (% by weight); N 2.50 (% by weight). The theoretical value calculated from the composition formula of C ₆₀ H ₄₆ F ₁₂ N ₂ S ₄ is C 62.60 (% by weight);
3 (% by weight); N 2.43 (% by weight).

After dissolving Compound 2 in hexane and irradiating with ultraviolet light (wavelength 313 nm), the specific rotation [α] at 633 nm was measured, and a value of 1200 ° was obtained.

The following formula shows the photoisomerization reaction that occurs when compound 2 is irradiated with ultraviolet light.

[0033]

Embedded image

In compound 2 before irradiation with ultraviolet light, two groups having a diarylethene structure in the molecule are both ring-opened (hereinafter also referred to as "two-ring-opened"). It changes to one in which only one is a closed ring (hereinafter, also referred to as “one closed ring”) and one in which both groups are closed rings (hereinafter, also referred to as “two closed rings”).

Reference Example After irradiating the compound 2 with ultraviolet light (wavelength 313 nm), the compound 2 was subjected to high-performance liquid chromatography (HPLC).
One and two closed forms were isolated. The two ring-opened bodies and the isolated one-ring-closed body and two-ring-closed body were each dissolved in hexane, and the CD spectrum of each was measured at room temperature (measurement apparatus: JASCO J-700). The result is shown in FIG. As shown in FIG. 1, no CD spectrum appeared around 550 nm for the two-ring-opened and one-ring-closed forms, and a CD spectrum appeared at about 550 nm for only the two-ring-opened form. It is well known that the CD spectrum has a close relationship with the optical rotation dispersion curve (curve indicating the wavelength dependence of specific rotation), and the above fact indicates that only two ring-closed bodies have a wavelength of 600 nm.
This indicates that a large specific rotation is observed even in a long wavelength region exceeding. Actually, when the specific rotation at 633 nm was measured for the two ring-opened product and one ring-closed product, each of them was 100 ° or less. In addition, the same measurement was performed for Compound 1, and the specific rotation at 633 nm of the two-ring open form and the one-ring closed form was 100 degrees or less in each case.

Compound 2 was treated with ultraviolet light (wavelength 313 n).
FIG. 1 also shows the irradiation time dependency of the CD spectrum when m) was irradiated. A CD spectrum does not appear in the early stage of irradiation, and a production curve is shown along the S-shaped curve, indicating that the two groups having a diarylethene structure in compound 2 are independently undergoing photoisomerization.

[Brief description of the drawings]

FIG. 1 is a CD spectrum of various isomers of Compound 2 (two open, one closed and two closed).

FIG. 2 is a graph showing a time-dependent change in a CD spectrum at 556 nm when the compound 2 (two-ring-opened product) is irradiated with ultraviolet light.

Claims (4)

[Claims] 1. A photochromic material comprising an optically active compound having a plurality of organic groups exhibiting photochromic properties in a molecule. 2. The photochromic material according to claim 1, wherein the organic group exhibiting photochromic properties is an organic group having a diarylethene structure having a hetero 5-membered ring in the aryl moiety. 3. An optically active compound having a plurality of organic groups exhibiting photochromic properties in a molecule thereof, wherein (1R, 2R)-
2. An optically active compound in which two monovalent organic groups having a diarylethene structure having a hetero 5-membered ring in the aryl moiety are bonded to a divalent organic group having a (-)-trans-diaminocyclohexane structure. Photochromic material. 4. The following formula: (In the formula, R ¹ and R ² are each independently a group represented by the following formula.) A bisdiarylethene compound represented by the formula: