JP3358682B2 - Benzothiophene-thiophene type diarylmaleimide derivative, photochromic material and optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel benzothiophene-thiophene type diarylmaleimide derivative, a photochromic material, and an optical recording medium using the same.

[0002]

2. Description of the Related Art Heretofore, photochromic materials which develop or decolor by irradiation with light have been widely used for various uses such as optical recording media, optical filters such as sunglasses, masking materials, and display materials.

[0003] As such a photochromic material,
Various organic compounds are known, and a typical example is a spiropyran-based compound (for example,
No. 5-28892).

[0004] It is also known that diarylethene derivatives are useful as photochromic materials. For example, JP-A-3-75635 and JP-A-3-148.
No. 258, the following formula (3)

Embedded image In the formula, a photochromic material comprising a diarylmaleic anhydride derivative in which Me is a methyl group (the same applies hereinafter) is described.

[0005] Further, Japanese Patent Application No. Hei.
No. 68926 discloses a compound represented by the following formula (4) in order to improve the chemical stability of the diarylmaleic anhydride of the above formula (3).

Embedded image It has been proposed to use a diarylmaleimide compound as a photochromic material.

[0006]

The photochromic material causes coloration or decoloration due to isomerization of the molecular structure accompanying light irradiation, but the photochromic material has a high quantum yield of coloration or decoloration. It is required that the quantum yield of coloring or decoloring be high, that the coloring be clear, that the contrast between coloring and decoloring be high, and that the state of coloring or decoloring be relatively stable. You.

However, in the above-mentioned diarylmaleimide derivative of the formula (4), although the chemical stability is improved, the quantum yield of the ring-closure reaction is reduced by about one digit as compared with the compound of the formula (3). It was also found that the isomerization rate (conversion rate,%) to isomerized molecules (ring-closed molecules) was reduced to 49%.

Accordingly, an object of the present invention is to provide a novel diarylmaleimide derivative which has an improved quantum yield of a ring closure reaction and is easily closed and hardly opened by irradiation of light.

Another object of the present invention is to provide a photochromic material having an improved isomerization rate, an excellent image contrast, a low quantum yield of a ring-opening reaction and an improved record retention, and a photochromic material having the same. To provide an optical recording medium using the same.

[0010]

According to the present invention, the following formula (1) is provided.

Embedded image Or the following equation (2)

Embedded imageWhere:R represents an alkyl group, a cyano group, an amide group,
Selected from the group consisting of xyl and alkoxycarbonyl groups
A substituted alkyl group having the selected group as a substituent In
And R ¹ Is an alkoxy group or an alkylthio group, R ² Is a lower alkyl group having 4 or less carbon atoms, R ³ Is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms
And  Ring A may be unsubstituted or an alkyl group, an alkoxy group,
Or a diarylmaleimide derivative, which may be substituted with a halogen atom.
You.

According to the present invention, there is further provided a photochromic material comprising the diarylmaleimide derivative of the above formula (1) or (2).

According to the present invention, there is further provided an optical recording medium comprising a substrate provided with a layer containing the diarylmaleimide derivative of the above formula (1) or (2).

[0013]

The compound of the present invention is characterized in that it has a benzothiophene ring and a thiophene ring at the 2- and 3-positions of the maleimide skeleton, respectively, and an electron-donating group at the 2-position of the benzothiophene ring. It is.

By introducing an electron-donating group such as an alkoxy group at the 2-position of a diarylmaleimide derivative having a combination of a benzothiophene ring and a thiophene ring, the quantum yield of the ring-closing reaction is remarkably improved, and the ring-opening reaction is improved. It was found that the quantum yield of the reaction was reduced, and as a result, the isomerization ratio by light irradiation was remarkably improved, and a high-contrast image forming ability and a stable retention of recording were obtained. See example).

In the present invention, the compound of the general formula (1) is a ring-opened compound, and the compound of the general formula (2) is a closed-ring form (cyclohexadiene), and the ring-opened form is generally orange. On the other hand, the closed ring is green and has a different hue, and a high contrast can be obtained in combination with the fact that the quantum yield of the closed ring is about one order of magnitude higher than that of the open ring.

The attached drawing "FIG. 1" shows the excitation light (wavelength 445 nm) of the ring-closed body (A) of the diarylmaleimide derivative of Example 1, the ring-opened body (B) of the diarylmaleimide derivative and the ring-opened body (B). 4) is an absorption spectrum of the sample (C) irradiated with the light. According to the result of FIG.
The ring-opened form (B) is almost transparent to light rays longer than 500 nm, whereas the ring-opened form (A) shows remarkable absorption for this light ray, and reads a high-contrast image. It can be seen that is possible. In addition, ring-opened form (B)
Isomerization to a closed form (A or C) at a wavelength of 500 nm
It is also clear that this can easily be done with shorter excitation light.

The maleimide derivative of the present invention has a large quantum yield for a ring-closed product and a small quantum yield for a ring-opened product, so that it can be used as a general photochromic material such as a color filter. However, it is particularly useful as an optical recording medium.

Referring to FIG. 2 for explaining the function as an optical recording medium, an optical recording medium 1 is obtained by dissolving a maleimide derivative of the present invention in a polymer on a substrate (transparent substrate) 2. It is made up of what is provided. The recording layer 3 has a ring-opened body (shown in white ) before writing A.
) . Next, when writing B, the wavelength 50
Irradiate light 4 shorter than 0 nm. As a result, the light portion L
In the above, a ring closed form (shown by oblique lines) of the maleimide derivative is generated, and in the dark part D, the maleimide derivative remains as an open ring. At the time of reading C, when the recording layer 6 to which the information is written is irradiated with the light ray 5 having a wavelength longer than 500 nm, the light ray is transmitted in the dark part D and the light ray is cut off in the light part L, so that the light ray image (negative image) is reproduced. can do. Once the recording layer 6 has been written, the ring opening quantum yield is low.
By storing this in a dark place, it can be used to reproduce a predetermined number of light beam images. By irradiating the used recording layer 6 with light 7 having a wavelength of 500 nm or more from a high-output light source in the erasing step D, the ring can be opened and erased.

[0019]

Preferred Embodiment of the Invention [Maleimide Derivative] In the maleimide derivative of the general formulas (1) and (2) of the present invention, R is an alkyl group such as methyl, ethyl,
Lower alkyl groups having 4 or less carbon atoms, such as propyl and butyl groups
And a methyl group is particularly preferred.

The above alkyl group is a cyano group, an amide
Group, carboxyl group and alkoxycarbonyl group.
May be substituted with a substituent selected from a certain group. Or
As such a substituent, a cyano group is preferable.

At the 2-position of the benzothiophene ringGroup R
¹ Is an electron-withdrawing group, such as an alkoxy group or an
Is a thio group.Alkoxy groupAs methoxy,
Lower alkoxy such as ethoxy, propoxy and butoxy groups
Groups, especially methoxy groups without steric hindrance, are preferred. Al
As the alkylthio group, a lower alkylthio group, particularly methyl
Thio groups and ethylthio groups are preferred.

The group R ^{2 of the} thiophene ring is a lower alkyl group having 4 or less carbon atoms such as a methyl, ethyl, propyl and butyl group, and is preferably a methyl group having little steric hindrance.
The group R ^{3 of the} thiophene ring is a hydrogen atom or a carbon atom.
It is a lower alkyl group of 4 or less , and a methyl group is preferable.

The ring in the benzothiophene ring may be unsubstituted or substituted with an alkyl group, an alkoxy group or a halogen atom. Examples of the halogen atom include a chlorine atom, a fluorine atom, and a bromine atom.

Examples of suitable compounds are as follows:
2- (2-methoxy-3-benzothienyl) -3-
(2,3,5-trimethyl-4-thienyl) -N-cyanomethylmaleimide. 2- (2-methylthio-3-benzothienyl) -3- (2,3,5-trimethyl-4-thienyl) -N-cyanomethylmaleimide.

[Synthesis Method] The maleimide derivative of the present invention is
The following equation (5)

Embedded image An oxamoylbenzothiophene derivative represented by the following formula (6):

Embedded image In the formula, X is a halogen atom, and is synthesized by dehydrating and cyclizing the thiophenyl-3-acetyl halide derivative at the same time as the condensation. This condensation reaction is a dehydrochlorination reaction and is carried out in the presence of an acid binder such as amines.

The thiophenyl-3-acetyl halide derivative of the above formula (6) is synthesized as follows. That is, the following equation (7)

Embedded image As shown in the reaction formula, a chloromethyl group is introduced into the 3-position of the thiophene to give a 3-chloromethyl derivative, the chlorine atom of this derivative is substituted with a cyano group, and then the cyano group is hydrolyzed to a carboxyl group. To an acid halide.

[Use] The maleimide derivative of the present invention is useful as a photochromic material. That is, the maleimide derivative is dissolved in a polymer, and the composition is formed into a film or formed into an appropriate shape, and used as a photochromic material.

In order to dissolve the maleimide derivative in the polymer, a method of dissolving the solution of the maleimide derivative in a previously formed polymer solution and casting or forming the solution by means of casting or the like can be used. .
Alternatively, as another method, a maleimide derivative is dissolved in a polymerization-curable monomer or prepolymer, and this is formed into a film by molding or other means, and then polymerized and cured.

As the polymer, a resin having excellent optical properties is used, for example, a styrene-based polymer, an acrylic-based polymer, a styrene-acryl-based copolymer or a carbonate-based polymer.

Examples of polymerization-curable monomers include ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, mono- or di-ethyl maleate, vinyl acetate, vinyl propionate, acrylamide, methacrylamide, maleimide, Acrolein, methacrolein, vinyl methyl ketone, vinyl butyl ketone, acrylonitrile, methacrylonitrile, propyl γ-hydroxymethacrylate, ethyl β-hydroxyacrylate, vinyl methyl ether, vinyl ethyl ether, allyl ethyl ether, glycidyl acrylate, glycidyl methacrylate , Glycidyl vinyl ether, styrene, etc., as well as multifunctional monomers such as polyalkylene polyol (meth) acrylate, bisdiethylene glycol carbonate DOO, divinylbenzene and the like,
Used in combination with a radical initiator.

During the polymerization, the benzothiophene of the present invention
There is no problem if a reaction such as grafting occurs between the indole-substituted maleimide derivative and the polymer.

The maleimide derivative of the present invention can be used alone as a photochromic material, or can be used as a photochromic material in combination with another photochromic material. In the latter case, the color tone at the time of color development is desired. There is an advantage that the color can be adjusted.

When used as an optical recording material, a maleimide derivative-soluble polymer alone can be used, but generally, a maleimide derivative-soluble polymer composition is coated on the surface of a plastic film such as biaxially stretched PET as a recording layer. It is good to use what was coated as. For applications that do not require light transmittance, paper or metal foil may be used as the substrate.

[0034] As the ultraviolet to develop the maleimide derivative of the present invention are advantageously UV such 253.7nm or 184.9 nm, whereas, as the laser beam as a heat source during writing, the He, Ne, CO _2, A
Gas lasers such as r ion and excimer, solid lasers such as alexandrite, YAG, ruby, and glass are used.

[0035]

The present invention will be described in more detail with reference to the following examples.

Synthesis Example 1 2- (2-methoxy-3-benzothienyl) -3-
(2,4,5-trimethyl-3-thienyl) -N-cyanomethylmaleimide was synthesized as follows.

Synthesis of 2,3,5-trimethylthiophene: 9.82 ml (0.4 ml) in a 500 ml four-necked flask.
1 mol) of 3-methylthiophene and dry ether 50
Then, 36.2 ml (0.24 mol) of tetramethylethylenediamine was added. Next, 150ml
(0.24 mol) of a n-BuLi hexane solution was slowly dropped at room temperature using a dropping funnel. Then about 40
15.7 ml (0.24 ml) with ice cooling.
mol) of methyl iodide / dry ether (50 ml) was slowly added dropwise using a dropping funnel. After stirring for about 1 hour while cooling with ice, the mixture was poured into about 100 ml of ice water, the organic layer was separated, and the aqueous layer was extracted three times with ether. The organic layers were combined, washed twice with diluted hydrochloric acid, then with water, and then dried over anhydrous magnesium sulfate. The solvent is distilled off, and the obtained liquid is distilled under reduced pressure to form a colorless liquid of 2,3,5-trimethylthiophene, that is, the following formula (8)

Embedded image Was obtained. Yield 9.35 g Yield 74.5% bp 72-77 ° C./55 mmHg ¹ H NMR (CDCl ₃ ) δ = 2.05 (s, 6H, Ar—CH ₃ ) 2.23 (s, 6H, Ar—CH) _{3) 2.33 (s, 3H,} Ar-CH 3) 6.35 (s, 1H, Ar-H)

Synthesis of 3-chloromethyl-2,4,5-trimethylthiophene: 3.16 g in a 200 ml four-necked flask equipped with a calcium chloride tube and a condenser tube on the top.
(25 mmol) of 2,3,5-trimethylthiophene [formula (8)] and 25 ml of 1,2-dichloroethane were added, and 9.5 ml (125 mmol) of chloromethyl methyl ether was added dropwise at room temperature, and then 0.34 g. (2.
5 mmol) of zinc chloride at room temperature. After stirring at room temperature for 1 hour, the reaction solution was poured into water, the organic layer was separated, and the aqueous layer was extracted three times with chloroform. The organic layers were combined and dried over anhydrous magnesium sulfate. The solvent was distilled off, and the obtained liquid was distilled under reduced pressure to give 3-chloromethyl-2, a colorless liquid.
4,5-trimethylthiophene, that is, the following formula (9)

Embedded image I got Yield 2.51 g Yield 57.4% bp 43-45 ° C./2 mmHg ¹ H NMR (CDCl ₃ ) δ = 2.06 (s, 3H, Ar—CH ₃ ) 2.23 (s, 3H, Ar—CH) _{3) 2.36 (s, 3H,} Ar-CH 3) 4.43 (s, 2H, Ar-CH 2 -Cl)

Synthesis of 3-cyanomethyl-2,4,5-trimethylthiophene: In a 200 ml four-necked flask
30 ml of water and 3.68 g (75 mmol) of sodium cyanide were added and stirred at about 30 ° C. to dissolve sodium cyanide. 0.24 g (0.75 mmol) of tetra-n-butylammonium bromide (catalyst for interlayer transfer)
Then, 8.73 g (50 mmol) of 3-chloromethyl-2,4,5-trimethylthiophene [formula (9)] was gradually added dropwise using a dropping funnel. After the addition was completed, the mixture was refluxed for 1 hour. After cooling to room temperature, 20m of water
The organic layer was separated and the aqueous layer was extracted three times with ether. The organic layers were combined and dried over anhydrous magnesium sulfate. The solvent is distilled off, and the obtained oily liquid is distilled under reduced pressure to give colorless liquid 3-cyanomethyl-2,4,5-trimethylthiophene, that is, the following formula (10)

Embedded image I got Yield 6.82 g Yield 82.7% bp 68-71 ° C./2 mmHg ¹ H NMR (CDCl ₃ ) δ = 2.07 (s, 3H, Ar—CH ₃ ) 2.27 (s, 3H, Ar—CH) _{3) 2.33 (s, 3H,} Ar-CH 3) 3.38 (s, 2H, Ar-CH 2 -CN)

Synthesis of 2,4,5-trimethyl-3-thienylacetic acid: 0.20 g in a 100 ml eggplant flask
(1.21 mmol) of 4-cyanomethyl-2,3,5
-Trimethylthiophene [formula (10)] and concentrated hydrochloric acid 4
Then, the mixture was refluxed for 3 hours. The reaction solution was poured into water and made alkaline with an aqueous solution of potassium hydroxide. The aqueous layer was washed with ether, acidified with diluted hydrochloric acid and extracted three times with ether. After drying over anhydrous magnesium sulfate, the solvent was distilled off, and white solid 2,4,5-trimethyl-3-thienylacetic acid, that is, the following formula (11)

Embedded image Was obtained. Yield 0.150 g Yield 67.4% ¹ H NMR (CDCl ₃ ) δ = 2.00 (s, 3 H, Ar—CH ₃ ) 2.22 (s, 3 H, Ar—CH ₃ ) 2.28 (s _{, 3H, Ar-CH 3)} 3.35 (s, 2H, Ar-CH 2 -COOH)

2- (2-methoxy-3-benzothienyl) -3- (2,4,5-trimethyl-3-thienyl)
Synthesis of -N-cyanomethylmaleimide: 50 ml of 3
0.104 g (0.55 mmol) of 2,4,5-trimethyl-3-thienylacetic acid [formula (11)] and 10 ml of dry benzene were placed in a single-necked flask, and 0.17 ml of oxalyl chloride was added to this solution. .37mmo
l) was added at room temperature. After stirring at room temperature for about 2 hours, the mixture was heated under reflux for 1 hour. The solvent and oxalyl chloride are distilled off,
This was dissolved in 5 ml of 1,2-dichloroethane and 153 mg (0.55 mmol) prepared in advance.
The following equation (12)

Embedded image Was added dropwise to a mixed solution of 2-methoxy-3- (N-cyanomethyloxamoyl) benzothiophene, 5 ml of triethylamine and 10 ml of 1,2-dichloroethane at room temperature. After stirring at room temperature for about 10 hours, water was added and extracted with chloroform. The organic layer was washed with dilute hydrochloric acid, then with water, and then dried over anhydrous magnesium sulfate. The solvent was distilled off, and the obtained solid was separated on a silica gel column to give 2- (2-methoxy-3-benzothienyl) -3- as a yellow solid.
(2,4,5-trimethyl-3-thienyl) -N-cyanomethylmaleimide, that is, the following formula (13)

Embedded image Was obtained. Yield 0.077 g Yield 31.9% ¹ H NMR (CDCl ₃ ) δ = 1.84 (s, 3 H, Ar—CH ₃ ) 1.95 (s, 3 H, Ar—CH ₃ ) 2.20 (s) _{, 3H, Ar-CH 3)} 3.74 (s, 3H, Ar-OCH 3) 4.50 (s, 2H, N-CH 2 -CN) 7.00-7.70 (m, 4H, aromatic p
rotons) Elemental analysis cal. C: 62.56 H: 4.26
N: 6.63 fon. C: 62.48 H: 4.21 N: 6.61 m. p. 72.4 ° C

2- (2-methylthio-3-benzothienyl) -3- (2,3,5-trimethyl-3-thienyl)
Synthesis of -N-cyanomethylmaleimide: 0.104 g (0.55 mmol) of 2,4 in a 50 ml three-necked flask
4,5-trimethyl-3-thienylacetic acid [the formula (1)
1)] and 10 ml of dry benzene were added, and 0.20 ml (1.42 mmol) of oxalyl fluoride was added to this solution at room temperature. After stirring at room temperature for about 2 hours, the mixture was heated under reflux for 1 hour. The solvent and oxalyl fluoride were distilled off, and this was dissolved in 1,2-dichloroethane (10 ml) to prepare 125 mg (0.55 mol) of the following formula (14) prepared in advance.

Embedded image Was added dropwise to a mixed solvent of 2-methylthio-3- (N-cyanomethyloxamoyl) benzothiophene, 5 ml of triethylamine and 10 ml of 1,2-dichloroethane at room temperature. After stirring at room temperature for about 10 hours, water was added and extracted with chloroform. The organic layer was washed with dilute hydrochloric acid, then with water, and dried over anhydrous magnesium sulfate. The solvent was distilled off and the resulting solid was separated on a silica gel column to give a yellow solid, 2- (2-methylthio-3-benzothienyl)-.
3- (2,4,5-trimethyl-3-thienyl) -N-
Cyanomethylmaleimide, that is, the following formula (15)

Embedded image I got Yield 0.59 g (Yield 21.5%) ¹ H NMR (CDCl ₃ ) δ = 1.33 (s, 3 H, Ar—CH ₃ ) 1.54 (s, 3 H, Ar—CH ₃ ) 1.76 (s, 3H, Ar-CH 3) 2.59 (s, 3H, Ar-S Me) 4.52 (s, 2H, N- CH 2 -CN) 5.95~7.71 (m, 4H, aromatic p
rotons) Elemental analysis cal. C: 60.27 H: 4.11
N: 6.39 fon. C: 60.30 H: 4.22 N: 6.45

Example 1 (Measurement of isomerization rate) The above formula (13)

Embedded image (1 × 10 ⁻⁴ mol / l) of a compound (hereinafter referred to as compound 1) in hexane as a solvent has an excitation wavelength (445 n).
m) and irradiate well. This is separated into a closed-ring form and a ring-opened form by liquid chromatography. The above ring-closure solution was dried under reduced pressure, dissolved in hexane, and the absorption spectrum of only the ring-closure was measured. 52 to this ring closure solution
Light having a wavelength of 0 nm or more was taken out through a cut filter and irradiated to form a ring-opened body, and then the absorption spectrum of this ring-opened body alone was measured. Further, an excitation wavelength (445) is added to this ring-opened solution.
nm), the light was brought into a steady state, and the absorption spectrum was measured. The measurement of the absorption spectrum of each solution was performed using a spectrophotometer Hitachi UV-3400A. The results are shown in FIG.

The following equation (16)

Embedded image The absorption spectrum of each compound in which R ⁴ is a group C ₁₈ H ₃₇ (hereinafter referred to as compound 2) was measured in the same manner as described above.

From the measurement results, the isomerization ratios of Compound 1 and Compound 2 in hexane were as follows.

The isomerization ratio was calculated based on the absorbance (A ') at the maximum absorption wavelength (λmax) of the ring-closed product and 445 nm
And the absorbance at λmax (C ′) of the irradiated material with the excitation wavelength of was calculated by the formula (C ′ / A ′) × 100.

(Measurement of quantum yield) The following equation (17) having a known quantum yield

Embedded image Fulgide compound (ring opening reaction Φ: 0.048 (492n
m) ε ₁ = 8200—hereinafter referred to as compound 3)
The light amount at 92 nm was measured with a light meter (International Light, Research Radiometer IN1700), and the result was set as α.

A sample (optically thin sample) having a sufficiently low absorbance of the hexane solution of the compound 3 was prepared (wavelength 492).
Absorbance in nm: 0.2 abs). 492n
m, irradiate light to cause a ring closure reaction, and plot logA (t) against irradiation time t (A is the absorbance at λmax of the closed ring after irradiation for t hours). The slope Δ1 of the straight line obtained from the plot is obtained.

A sample (optically thin sample) having a sufficiently low absorbance of the hexane solution of the compound 2 was prepared (wavelength 445).
Absorbance in nm: 0.2 abs). 490n in this solution
m, irradiate light to cause a ring closure reaction, and plot logA (t) against irradiation time t (A is the absorbance at λmax of the closed ring after irradiation for t hours). The slope Δ2 is obtained from the straight line obtained from the plot.

The excitation wavelength of the ring closure reaction of the compound 2 is 445.
The light amount in nm is measured, and the result is set as β.

Similarly, a sample in which the absorbance of the hexane solution of the compound 2 was sufficiently low was prepared (absorbance at a wavelength of 560 nm: 0.2 abs). The solution is irradiated with light of 560 nm to cause a ring opening reaction, and logA (t) with respect to time t.
Is plotted, and the slope Δ3 of this straight line is obtained.

Excitation wavelength of the ring opening reaction of compound 2 is 560 nm
Is measured by a light meter, and the result is defined as γ. Relative quantum yield of ring closure reaction (open → closed: 445 nm) Δ1: Δ2 = 8200 × 0.048 × α: 8200 × Φ
Ф (quantum yield of ring closure reaction of compound 2) was calculated from × β.
Further, the relative quantum yield of the ring opening reaction (closed → open: 560 nm) Δ1: Δ3 = 8200 × 0.048 × α: 8200 × Φ
Ф ′ (quantum yield of ring-opening reaction of compound 2) was calculated from ´ × γ.

Compound 1 was calculated in the same manner as above.

The calculated results are shown below. Relative quantum yield ε Ring closing reaction Ring opening reaction Ring closed compound Compound 1 0.24 0.075 10000 Compound 2 0.013 0.12 8200

Example 2 Compounds 1 and 2 were dissolved in toluene, and dissolved in polystyrene so that the concentration in polystyrene was 0.2 mol% per styrene unit.
And dried to obtain a recording film. The color tone of the ring-opened product was orange.

The recording film was irradiated with light of 490 to 500 nm to prepare a clear green recording original plate. After the original plate was left under room light for 50 days, the original plate of Compound 1 remained bright green.

The recording film has a thickness of 490 to 500 nm.
And the recording was performed. The recording on the recording film of Compound 1 was a clear green color, and had a high contrast with the unrecorded portion.

On the other hand, it was confirmed that the recording film of Compound 2 did not develop color under room light.

[0059]

According to the present invention, there is provided a compound having a benzothiophene ring and a thiophene ring at the 2- and 3-positions of the maleimide skeleton and an electron-donating group at the 2-position of the benzothiophene ring. .

By introducing an electron-donating group such as an alkoxy group at the 2-position of the diarylmaleimide derivative having a combination of a benzothiophene ring and a thiophene ring, the quantum yield of the ring-closing reaction is remarkably improved, and the ring-opening reaction is improved. The quantum yield of the reaction is reduced, and as a result, the isomerization ratio by light irradiation is remarkably improved, so that a high-contrast image forming ability and stable recording retention can be obtained.

In the present invention, the compound of the general formula (1) is a ring-opened product, and the compound of the general formula (2) is a closed-ring product (cyclohexadiene), and the ring-opened product is generally orange. On the other hand, the closed ring is green and has a different hue, and a high contrast can be obtained in combination with the fact that the quantum yield of the closed ring is about one order of magnitude higher than that of the open ring.

The maleimide derivative of the present invention has a large quantum yield for a ring-closed product and a small quantum yield for a ring-opened product, so that it can be used as a general photochromic material such as a color filter. However, it is particularly useful as an optical recording medium.

[Brief description of the drawings]

FIG. 1 shows that the diarylmaleimide derivative of Example 1 has a closed form (A), a ring-opened form (B) of the diarylmaleimide derivative, and an excitation light (wavelength 445 n).
m) shows the absorption spectrum of the sample irradiated with m) (C).

FIG. 2 is an explanatory diagram for explaining an operation as an optical recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 Substrate (transparent substrate) 3 Recording layer 4 Writing light 5 Reading light 6 Recording layer 7 Reproduction light D Dark part L Light part

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C07D 409/14 C07D 495/14 CA (STN) REGISTRY (STN)

Claims (7)

(57) [Claims] [Claim 1] The following formula (1)Or the following formula (2):Where:R represents an alkyl group, a cyano group, an amide group,
Selected from the group consisting of xyl and alkoxycarbonyl groups
A substituted alkyl group having the selected group as a substituent
And R ¹ Is an alkoxy group or an alkylthio group, R ² Is a lower alkyl group having 4 or less carbon atoms, R ³ Is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms
And  Ring A may be unsubstituted or an alkyl group, an alkoxy group,
Or a diarylmaleimide derivative which may be substituted with a halogen atom. 2. A lower alkoxy group wherein R ¹ has 4 or less carbon atoms.
The diarylmaleimide derivative according to claim 1, which is a lower alkylthio group having 4 or less carbon atoms . 3. The diarylmaleimide derivative according to claim 1, wherein R is a cyanoalkyl group. 4. In the formula (1) or (2), R is a cyanomethyl group, R ¹ is a methoxy group, R ² is a methyl group, R ³ is a methyl group, and The diarylmaleimide derivative according to claim 1, wherein A is unsubstituted. 5. In the formula (1) or the formula (2), R is a cyanomethyl group, R ¹ is a methylthio group, R ² is a methyl group, R ³ is a methyl group,
The diarylmaleimide derivative according to claim 1, wherein ring A is unsubstituted. 6. The following formula (1):Or the following formula (2):Where:R represents an alkyl group, a cyano group, an amide group,
Selected from the group consisting of xyl and alkoxycarbonyl groups
A substituted alkyl group having the selected group as a substituent
And R ¹ Is an alkoxy group or an alkylthio group, R ² Is a lower alkyl group having 4 or less carbon atoms, R ³ Is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms
And  Ring A may be unsubstituted or an alkyl group, an alkoxy group,
Or a diarylmaleimide derivative, which may be substituted with a halogen atom.
A photochromic material characterized by the following. 7. The following formula (1)Or the following formula (2):Where:R represents an alkyl group, a cyano group, an amide group,
Selected from the group consisting of xyl and alkoxycarbonyl groups
A substituted alkyl group having the selected group as a substituent
And R ¹ Is an alkoxy group or an alkylthio group, R ² Is a lower alkyl group having 4 or less carbon atoms, R ³ Is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms
And  Ring A may be unsubstituted or an alkyl group, an alkoxy group,
Or a layer containing a diarylmaleimide derivative, which may be substituted with a halogen atom.
An optical recording medium comprising: a substrate;