JP2001262135A - Photochromic material and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photochromic material suitable for recording materials, composed of a ring-opening substance whose absorption band extends to the vicinity of visible range and an optical recording medium using the above material, excellent in repeated durability and irreversibility to heat on the occasion of recording, erasing and reproduction and having low production cost. SOLUTION: This photochromic material is composed of a diarylethene-based compound represented by a general formula 1 [R1 is an alkyl group which may be substituted or an alkoxy group which may be substituted; R2 to R7 are each hydrogen atom or an alkyl group which may be substituted or an alkoxy group which may be substituted or an aryl group which may be substituted; and A is a thiophene or a benzothiophene derivative].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a photochromic material and an optical recording medium using the same.

[0002]

2. Description of the Related Art When recording and erasing information on a recording medium, a rewritable recording medium is usually used. As an information rewritable recording medium, an optical recording medium using a photochromic material photoreaction, that is, a photochromic reaction has been proposed.

[0003] The photochromic reaction means that a photochromic material in the state A is irradiated with light having a wavelength λ1 in which the state A absorbs, thereby producing a state B in which light of a different wavelength is absorbed. Is a reversible reaction that returns to the original state of A by irradiating the photochromic material in the state of state A with light having a wavelength λ2 in which the state B absorbs. In an optical recording medium utilizing the photochromic reaction, one of the states A and B is in an information non-recording state (a state in which no information is recorded), and the other is in an information recording state (an information recording state). Is recorded on the optical recording medium).

In an optical recording medium on which information can be rewritten using a photochromic reaction, when the recorded information is reproduced, the difference between the physical property value in the state A and the physical value in the state B is different. Should be detected. Since the light absorption spectrum before and after the photochromic reaction, that is, the state of A and the state of B are greatly different, for example, the difference between the light absorption intensity in the state A and the light absorption intensity in the state B at the wavelength λ2 , It is possible to read the information recorded state or the information unrecorded state, that is, to reproduce the information.

In order to use a photochromic material for an optical recording medium, good repetition durability and thermal irreversibility are required for recording, erasing and reproducing information. Diarylethene-based compounds have attracted attention as a photochromic material satisfying such requirements. In particular, a diarylethene-based compound in which two aryl groups are connected to a perfluorocyclopentene ring satisfies the above-mentioned required performance, and the route and steps for material synthesis are relatively simple and the synthesis yield is high.

In the photochromic reaction of a diarylethene-based compound having a perfluorocyclopentene ring (hereinafter simply referred to as a diarylethene-based compound), the above-mentioned A state and B state are often called ring-opened and ring-closed bodies, respectively. The closed form can absorb light of a longer wavelength than the open form, in other words, has an absorption band up to a long wavelength range. In many diarylethene compounds, the absorption band of the closed ring is in the visible range, but the absorption band of the open ring is in the ultraviolet range. For this reason, in an optical recording apparatus that accommodates an optical recording medium using a diarylethene-based compound and performs at least one of recording, reproducing, and erasing of information on the optical recording medium, the ring-opened body has an absorption wavelength of λ1. A light source such as a semiconductor laser that emits ultraviolet light is required as a light source that emits light.

[0007]

However, at present, no light source such as a semiconductor laser that operates stably in the ultraviolet region has been found. Even if such a light source is developed in the future, it is advantageous that the absorption band of the ring-opened body is as close to the visible region as possible. Because the shorter the wavelength of the light that the ring-opened body has absorption, that is, the light used for recording, reproducing and erasing information, the special optical components in the optical recording device must be used to cope with it. This is because the optical recording device becomes expensive. Therefore, as the diarylethene-based compound used for the optical recording medium, it is desirable to adopt a compound in which the ring-opened body has an absorption band in a longer wavelength region and closer to a visible light region.

As a diarylethene compound having a ring-opened compound having an absorption band in a relatively long wavelength range, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 89954, there is a diarylethene-based compound having a conjugated double bond chain.
There is a possibility that a cis form and a trans form occur at the double bond portion. Only the cis-form causes a photochromic reaction from the ring-opened form to the closed-form, and therefore, when the cis-form is changed to the trans-form, it is not possible to react with the closed-form. This causes a reduction in sensitivity (reduction in signal intensity) during reproduction, and is therefore inconvenient when used as a recording material.

As taught by JP-A-8-245579, diarylethene compounds having two aryl groups each having a thiophene ring and having a bond with a perfluorocyclopentene ring at the 2-position are also ring-opened compounds. Although the band is in the long wavelength range, the absorption band of the ring-opened compound and that of the ring-closed compound almost overlap with each other, making it difficult to control the direction of the photochromic reaction. In this case, recording or erasing becomes insufficient, which is inconvenient when used as a recording material.

Further, Chemistry Letters; p969 (1995)
Teaches that two aryl groups are thiophene rings, one of which is bonded to the perfluorocyclopentene ring at the 2-position and the other at the 3-position is an open-ring and closed-ring absorption in diarylethene-based compounds. The bands are separated. However, although the absorption band of the ring-opened body is in a relatively long wavelength region, it is still insufficient.

It is an object of the present invention to provide a photochromic material comprising a diarylethene-based compound, which is convenient for use as a recording material, and in which the absorption band of the ring-opened body reaches near the visible region. And

The present invention also relates to an optical recording medium for performing at least one of recording, reproducing and erasing of information by light using a photochromic material, wherein the recording and erasing of information is performed.
Excellent repetition durability and thermal irreversibility during regeneration,
It is another object of the present invention to provide an optical recording medium that can reduce the medium manufacturing cost and the cost of an optical recording device that houses the medium.

[0013]

The present invention provides the following photochromic material and optical recording medium to solve the above-mentioned problems. (1) Photochromic material A photochromic material comprising a diarylethene-based compound, wherein the diarylethene-based compound is a compound represented by the following general formula (1).

[0014]

Embedded image

(In the formula (1), R1 represents an alkyl group which may be substituted or an alkoxy group which may be substituted; R2 to R7 each represent a hydrogen atom or an alkyl group which may be substituted; A represents an optionally substituted alkoxy group or an optionally substituted aryl group, and A represents the following general formula (2)

[0016]

Embedded image

Or the following general formula (3)

[0018]

Embedded image

Represents a group represented by Where R11, R14
Represents an optionally substituted alkyl group or an optionally substituted alkoxy group, and R12, R13, R1
5 to R18 each represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, or an optionally substituted aryl group. (2) Optical recording medium An optical recording medium that performs at least one of recording, reproducing, and erasing of information by light using a photochromic material, and includes the photochromic material represented by the general formula (1). An optical recording medium characterized by the above-mentioned.

In the photochromic material according to the present invention, the alkyl group is represented by the general formula C _n H _{2n + 1-} . The range of n of the alkyl group is not particularly limited since it does not affect the main photochromic reaction characteristics, but usually the range of 1 to 3 is preferable. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. The alkoxy groups are - general formula C _n H _{2n + 1} is denoted by O-. The range of n of the alkoxy group is not particularly limited because it does not affect the main photochromic reaction characteristics, but usually the range of 1 to 3 is preferable. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

Examples of the aryl group include a phenyl group,
A naphthyl group and the like can be raised.

Examples of the substituent which may be substituted on the alkyl group or the alkoxyl group include a halogen atom, a nitro group, an amino group, a cyano group, an alkoxy group, an alkylthio group and a hydroxyl group. Examples of the substituent which may be substituted on the aryl group include, for example, the substituents exemplified for the alkyl group and the alkoxy group, and the alkyl group.

The photochromic material according to the present invention comprises a diarylethene compound represented by the above general formula, and causes a photochromic reaction by the diarylethene compound.

That is, the diarylethene compound in the ring-opened state has a wavelength λ1 at which the ring-opened body has absorption.
By irradiating light, a closed ring having absorption of light of a different wavelength is generated, and the diarylethene-based compound in the closed ring state has a wavelength λ2 at which the closed ring has absorption.
Irradiation of this light causes a reversible reaction to return to the original ring-opened state.

According to the photochromic material of the present invention,
Since the diarylethene-based compound is a compound having no conjugated double bond chain as shown in the general formula,
No. 89954, JP-A-8-245579, Ch.
Emistry Letters; p969 (1995) teaches no disadvantage such as the diarylethene compound, and is convenient for use as a recording material. Further, the absorption band of the ring-opened form of the diarylethene-based compound extends to a longer wavelength region than that of the conventional one, that is, to the vicinity of the visible region.

The optical recording medium according to the present invention contains the photochromic material according to the present invention. One of the ring-opened and ring-closed states of the diarylethene-based compound of the photochromic material has no information. By making the recording state correspond to the information recording state on the other side, it becomes an optical recording medium on which information can be rewritten.

According to the optical recording medium of the present invention, since a diarylethene compound is employed as a photochromic material, the optical recording medium is excellent in repetitive durability and thermal irreversibility in recording, erasing, and reproducing information. Further, this diarylethene-based compound is a diarylethene-based compound represented by the above general formula, and as described above, since the absorption band of the ring-opened body reaches near the visible region, the light in which the ring-opened body has absorption, that is, information Light near the visible region can be adopted as light used for recording, reproducing, and erasing. Therefore, it is not necessary to use a special optical component in the optical recording device that accommodates the medium, and the cost of the optical recording device can be reduced accordingly.

The "optical recording medium which performs at least one of recording, reproduction and erasure of information" is an optical recording medium which can perform all of recording, reproduction and erasure of information, and information is already recorded. And an optical recording medium capable of reproducing the information.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

The photochromic material according to the present invention comprises a diarylethene compound, and the diarylethene compound is a compound represented by the following general formula (1).

[0031]

Embedded image

(In the formula (1), R1 represents an alkyl group which may be substituted or an alkoxy group which may be substituted, and R2 to R7 each represent a hydrogen atom or an alkyl group which may be substituted, A represents an optionally substituted alkoxy group or an optionally substituted aryl group, and A represents the following general formula (2)

[0033]

Embedded image

Or the following general formula (3)

[0035]

Embedded image

Represents a group represented by Where R11, R14
Represents an optionally substituted alkyl group or an optionally substituted alkoxy group, and R12, R13, R1
5 to R18 each represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, or an optionally substituted aryl group. )
As examples of the present invention, methods for synthesizing the following four diarylethene-based compounds will be described. Example 1: 1- (2-methylbenzothiophen-3-yl) -2- (3-methyl-5-phenylthiophen-2
-Yl) perfluorocyclopentene Example 2: 1- (2-methylbenzothiophen-3-yl) -2- (3-methyl-5-biphenylthiophene-
2-yl) perfluorocyclopentene Example 3: 1- (2,4-dimethyl-5-phenylthiophen-3-yl) -2- (3-methyl-5-phenylthiophen-2-yl) perfluorocyclopentene Example 4: 1- (2,4-dimethyl-5-phenylthiophen-3-yl) -2--3-methyl-5- (4-methoxyphenyl) thiophen-2-yl) perfluorocyclopentene (Example 1 1a) Synthesis of 4-methyl-2-thiophenboronic acid 50 g (0.51 mol) of 3-methylthiophene was dissolved in 500 ml of anhydrous diethyl ether under an argon atmosphere, and N, N, N ′, N 86 ml (0.56 mol) of '-tetramethylethylenediamine was added, and the mixture was cooled to 0 ° C in an ice bath.
After cooling, 350 ml (0.56 mol) of 1.6 M n-butyllithium hexane solution was added dropwise, and the mixture was stirred for 1 hour, and then stirred for 12 hours while returning to room temperature. After cooling to 0 ° C again, tributyl n-butyl borate 150 ml (0.5
6 mol) was added dropwise and stirred for 1 hour, followed by stirring at room temperature for 2 hours. The solution was quenched with 1M dilute hydrochloric acid, made alkaline by adding a 1N aqueous sodium hydroxide solution, and the aqueous layer was extracted. While cooling the aqueous layer with an ice bath, hydrochloric acid was added until pH = 1, and the deposited precipitate was collected by suction filtration. Further, the precipitate is washed with dilute hydrochloric acid and then dried under reduced pressure to give Compound 6 of the following structural formula (4).
0.7 g (0.43 mol) was obtained. The yield was 84%.

[0037]

Embedded image

1b) Synthesis of 3-methyl-5-phenylthiophene 10.0 g of 4-methyl-2-thiophenboronic acid (0.0 g).
070 mol), iodobenzene 14.4 g (0.07
0 mol) and 4.11 g (0.0036 mol) of tetrakistriphenylphosphine palladium were dissolved in 500 ml of tetrahydrofuran. 250 ml of a 20% aqueous sodium carbonate solution was added thereto, and the mixture was heated to 70 ° C. under a nitrogen atmosphere.
And refluxed for 5 hours. After returning to room temperature, tetrahydrofuran was distilled off, followed by extraction with diethyl ether, which was washed with saturated saline and dried over magnesium sulfate. Magnesium sulfate was removed by filtration, and diethyl ether was distilled off. This was developed and separated with hexane using a silica gel column to give compound 9.2 of the following structural formula (5).
g (0.053 mol) was obtained. The yield was 75%.

[0039]

Embedded image

1c) Synthesis of 2-methylbenzothiophene 25 g (0.19 mol) of benzothiophene was dissolved in 100 ml of anhydrous diethyl ether under an argon atmosphere, and cooled to 0 ° C in an ice bath. To this, 125 ml of a 1.6 M n-butyllithium hexane solution (0.20 mol
l) was added dropwise, and the mixture was returned to room temperature and stirred for 12 hours. 0 ° C again
After cooling to 23.2 ml of methyl iodide (0.37 mol
l) was added dropwise, and the mixture was stirred overnight while returning to room temperature on an ice bath. The solution was quenched with 1M diluted hydrochloric acid, extracted with ether, and dried over magnesium sulfate. After removing magnesium sulfate by filtration and distilling ether,
The remaining solid was purified by recrystallization from hexane to obtain 18.8 g (0.13 mol) of a compound of the following structural formula (6). The yield was 68%.

[0041]

Embedded image

1d) Synthesis of 3-iodo-2-methylbenzothiophene 10.8 g of 2-methylbenzothiophene (0.073 m
ol), acetic acid 80 ml, water 31 ml, concentrated sulfuric acid 13 ml
9.0 g (0.036 mol) of iodine and 2.2 g (0.0097 mol) of periodic acid were added to
Heated for hours. After returning to room temperature, ice water was added, and the mixture was extracted with chloroform. The organic layer was washed with water, neutralized with an aqueous solution of sodium hydrogen carbonate, washed with an aqueous solution of sodium thiosulfate, and dried over magnesium sulfate. Magnesium sulfate was removed by filtration, and chloroform was distilled off. The remaining solid was purified by recrystallization from hexane to obtain 15.6 g (0.057 mol) of the compound of the following structural formula (7). The yield was 78%.

[0043]

Embedded image

1e) Synthesis of 1- (2-methylbenzothiophen-3-yl) perfluorocyclopentene 3-iodo-2-
5.0 g (0.018 mol) of methylbenzothiophene
And 100 ml of tetrahydrofuran. After cooling to −70 ° C. with stirring, 10 ml (0.016 mol) of a hexane solution of n-butyllithium was added dropwise and stirred for 30 minutes, and 1.5 ml (0.023 mol) of perfluorocyclopentene was further added at once. Was. After stirring for 2 hours, methanol, diluted hydrochloric acid and water were added to stop the reaction. After extracting the organic layer with diethyl ether, the organic layer was washed and dried, and then the solvent was distilled off under reduced pressure. The obtained reaction product was purified by silica gel chromatography to obtain 2.1 g ((0.0062 mol) of a compound of the following structural formula (8).
4%.

[0045]

Embedded image

1f) Synthesis of 1- (2-methylbenzothiophen-3-yl) -2- (3-methyl-5-phenylthiophen-2-yl) perfluorocyclopentene -Methyl-5-
0.87 g (0.0050 mol) of phenylthiophene
And 60 ml of tetrahydrofuran. After cooling to 0 ° C. while stirring, 3.5 ml (0.0056 mol) of a hexane solution of n-butyllithium was added dropwise and stirred for 30 minutes. Next, after cooling to −70 ° C., a solution of 1.7 g (0.0050 mol) of 1- (2-methylbenzothiophen-3-yl) perfluorocyclopentene / 20 ml of tetrahydrofuran which was separately adjusted and cooled to −70 ° C. Was added dropwise, and the mixture was stirred for 2 hours, and then stirred overnight while returning to room temperature. The reaction was stopped by adding methanol, dilute hydrochloric acid and water.

After extracting the organic layer with diethyl ether, the organic layer was washed and dried, and the solvent was distilled off under reduced pressure. The obtained reaction product was purified by silica gel chromatography to obtain a compound 1.1 of the following structural formula (9).
g (0.0022 mol) was obtained. The yield was 44%.

[0048]

Embedded image

(Method of synthesizing the material of Example 2) Step 1
A compound of the following lateral formula (10) was obtained in the same manner as in the synthesis procedure of the material of Example 1, except that 4-bromobiphenyl was used instead of iodobenzene in b).

[0050]

Embedded image

(Method for synthesizing the material of Example 3) 3a) Synthesis of 2,4-dimethylthiophene 75 g (0.76 mol) of 3-methylthiophene was dissolved in 500 ml of anhydrous diethyl ether under an argon atmosphere. 129 ml (0.84 mol) of N ', N'-tetramethylethylenediamine was added, and the mixture was added with ice bath.
Cooled to ° C. To this, 525 ml (0.84 mol) of 1.6 M n-butyllithium hexane solution was added dropwise, and the mixture was returned to room temperature and stirred for 12 hours. After cooling again to 0 ° C., 52.5 ml (0.84 mol) of methyl iodide was added dropwise, and the mixture was stirred overnight while returning to room temperature on an ice bath. The solution was quenched with 1M diluted hydrochloric acid, extracted with ether, and dried over magnesium sulfate. After magnesium sulfate was removed by filtration and ether was distilled off, distillation under normal pressure (boiling point １３13
2 ° C.) to give the compound of the following structural formula (11)
8.0 g (0.52 mol) were obtained. The yield was 68%.

[0052]

Embedded image

3b) Synthesis of 2,4-dibromo-3,5-dimethylthiophene 32 g (0.29 mol) of 2,4-dimethylthiophene
Was dissolved in 600 ml of acetic acid and cooled to 10 ° C. in a water bath.
100 g (0.63 mol) of bromine was added dropwise, and the mixture was stirred overnight while returning to room temperature. The solution was extracted with chloroform, and the organic layer was washed with water, neutralized with an aqueous solution of sodium hydrogen carbonate, washed with an aqueous solution of sodium thiosulfate, and dried over magnesium sulfate. The magnesium sulfate was removed by filtration, and the ether was distilled off. This is separated and developed with hexane using a silica gel column, and the following structural formula (12)
Was obtained in an amount of 49.4 g (0.18 mol). The yield was 64%.

[0054]

Embedded image

3c) 4-bromo-3,5-dimethyl-2
Synthesis of -thiophenboronic acid 2,4-dibromo-3,5-dimethylthiophene 30 g
(0.11 mol) was dissolved in 500 ml of anhydrous diethyl ether under an argon atmosphere, cooled to -70 ° C in a dry ice-methanol bath, and 78 ml (0.13 mol) of a 1.6 M n-butyllithium hexane solution was added dropwise. And stirred for 1 hour. Tri-n-butyl borate 4
After dropping 5 ml (0.17 mol) and stirring for 1 hour,
Stirred at room temperature for 2 hours. The solution was quenched with 1M dilute hydrochloric acid, made alkaline by adding a 1N aqueous sodium hydroxide solution, and the aqueous layer was extracted. While cooling the aqueous layer with an ice bath, hydrochloric acid was added until pH = 1, and the deposited precipitate was collected by suction filtration. Further, the precipitate is washed with dilute hydrochloric acid and then dried under reduced pressure to obtain the following structural formula (1)
20.9 g (0.089 mol) of the compound of 3) was obtained.
The yield was 80%.

[0056]

Embedded image

3d) 3-bromo-2,4-dimethyl-5
Synthesis of 4-phenyl-3,5-dimethyl-2-thiophenboronic acid 10.4 g (0.044 mol), iodobenzene 1
1.2 g (0.055 mol), tetrakistriphenylphosphine palladium 2.6 g (0.020 mol)
Was dissolved in 270 ml of tetrahydrofuran (THF). To this was added 120 ml of a 20% aqueous sodium carbonate solution, and the mixture was heated and refluxed at 70 ° C. for 5 hours under a nitrogen atmosphere. After returning to room temperature, THF was distilled off, followed by extraction with diethyl ether, which was washed with a saturated saline solution and dried over magnesium sulfate. Magnesium sulfate was removed by filtration, and diethyl ether was distilled off. This was separated and developed with hexane using a silica gel column, and the following structural formula (1)
9.35 g (0.035 mol) of the compound of 4) was obtained.
The yield was 79%.

[0058]

Embedded image

3e) Synthesis of 1- (2,4-dimethyl-5-phenylthiophen-3-yl) perfluorocyclopentene In a three-necked flask purged with argon, 3-bromo-2,
5.0 g of 4-dimethyl-5-phenylthiophene (0.
019 mol) and 100 ml of tetrahydrofuran. After cooling to −70 ° C. while stirring, n
14 ml of hexane solution of butyl lithium (0.022
mol) was added dropwise, and the mixture was stirred for 30 minutes, and 1.5 ml (0.023 mol) of perfluorocyclopentene was further added at once. After stirring for 2 hours, methanol, diluted hydrochloric acid and water were added to stop the reaction. After extracting the organic layer with diethyl ether, the organic layer was washed and dried, and the solvent was distilled off under reduced pressure. The obtained reaction product was purified by silica gel chromatography, and 3.08 g (0.0081 mol) of the compound of the following structural formula (15) was obtained.
I got The yield was 43%.

[0060]

Embedded image

3f) 1- (2,4-Dimethyl-5-phenylthiophen-3-yl) -2- (3-methyl-5
Synthesis of phenylthiophen-2-yl) perfluorocyclopentene In a three-necked flask purged with argon, 3-methyl-5-
1.13 g (0.0065 mol) of phenylthiophene
And 80 ml of tetrahydrofuran. After cooling to 0 ° C. while stirring, 4.7 ml (0.0075 mol) of a hexane solution of n-butyllithium was added dropwise and stirred for 30 minutes. 2.70 g of 1- (2,4-dimethyl-5-phenylthiophen-3-yl) perfluorocyclopentene which had been separately adjusted after cooling to -70 ° C and cooled to -70 ° C (0. 0068 mol) / tetrahydrofuran 30 ml solution was added dropwise, and the mixture was stirred for 2 hours, and then stirred overnight while returning to room temperature. methanol,
The reaction was stopped by adding diluted hydrochloric acid and water. After extracting the organic layer with diethyl ether, the organic layer was washed and dried, and the solvent was distilled off under reduced pressure. The obtained reaction product was purified by silica gel chromatography, and 2.05 g of the compound of the following structural formula (16) (0.0038 mol) was obtained.
1) was obtained. The yield was 59%.

[0062]

Embedded image

(Method of Synthesizing Material of Example 4) Step 3
In f), 3-methyl-5- (4-methoxyphenyl) thiophene was used in place of 3-methyl-5-phenylthiophene, and the following structure was used in the same manner as in the synthesis procedure of the material of Example 3. The compound of the formula (17) was obtained.

[0064]

Embedded image

The photochromic material manufactured as described above has the structural formulas (9), (10), (16) and (1).
7) a diarylethene compound represented by the formula:
A photochromic reaction is caused by the diarylethene compound. That is, a wavelength λ1 at which the ring-opened body has absorption is added to the diarylethene-based compound in the ring-opened state.
By irradiating light, a closed ring having absorption of light of a different wavelength is generated, and the diarylethene-based compound in the closed ring state has a wavelength λ2 at which the closed ring has absorption.
Irradiation of this light causes a reversible reaction to return to the original ring-opened state.

According to this photochromic material, the diarylethene-based compound has the structural formula (9), (10),
As shown in (16) and (17), since the compound does not have a conjugated double bond chain, it does not cause inconvenience like the diarylethene-based compound disclosed in JP-A-7-89954, and is used as a recording material. It is convenient for use.
Further, the structural formulas (9), (10), (16), (1)
The diarylethene-based compound shown in 7) has an absorption band of a ring-opened body extending to a longer wavelength region, that is, near to a visible region than the conventional one, and the absorption band of the ring-opened body and the ring-closed body have little overlap. There is no inconvenience such as the diarylethene compound disclosed in Japanese Unexamined Patent Publication No. 8-245579, which is convenient for use as a recording material. FIG. 1 is a cross-sectional view showing a schematic configuration of a part of an example of an optical recording medium manufactured using the photochromic material comprising the diarylethene-based compound of Examples 1 to 4, and FIG. 2 shows the optical recording medium shown in FIG. FIG. 1 shows a side view of a schematic configuration of an example of an optical recording device that accommodates and performs recording, erasing, and reproduction of information on the medium.

As shown in FIG. 1, an optical recording medium 94 is a recording layer 942 for recording information by applying the diarylethene compounds of Examples 1 to 4 and a polystyrene resin onto a glass substrate 941 by spin coating. A substrate 941 rotating at 3000 rpm using 2.5 parts by weight of a diarylethene compound, 2.5 parts by weight of a polysterene resin, and 95 parts by weight of toluene as a coating liquid.
The recording layer 942 is formed by spin coating. In this example, the thickness of the recording layer 942 is about 15
0 nm.

The optical recording medium 94 is formed by associating one of the ring-open and ring-closed states of the diarylethene compound with the information-unrecorded state and the other into the information-recorded state (here, the ring-opened state). By associating the state of the body with the information unrecorded state and the state of the closed body with the information recorded state, the optical recording medium becomes rewritable.

The optical recording apparatus shown in FIG. 2 has a light source 91 for information erasure and reproduction, a light source 97 for information recording, a wavelength selection mirror 9
2. It includes condenser lenses 93 and 95, a photodiode 96, an optical recording medium storage unit 100, and the like, and can perform any of recording, erasing, and reproducing of information on the optical recording medium 94.

The information erasing and reproducing light source 91 includes an ND filter 91 ′ capable of adjusting the intensity of light, and has a wavelength 51
4 nm light 91a can be emitted. Thereby, the light source 91
Has a wavelength of 514n as information erasing light when information is erased.
m, light 91 having an irradiation light power of about 1 mW on the recording medium
a can be injected. Note that the information erasing light is light having a wavelength at which the closed ring of the diarylethene compound in the medium 94 has absorption. At the time of information reproduction, light 91a having a wavelength of 514 nm and an irradiation light power of about 10 μW on the recording medium can be emitted as information reproduction light. Since the information reproducing light has a small irradiation light power of about 10 μW, the information on the medium 94 is hardly erased and can be ignored in practical use.

The information recording light source 97 includes an ND filter 97 ′ capable of adjusting the light intensity, and has a wavelength of 365 nm.
Light 97a can be emitted. Thus, the light source 97 can emit light 97a having a wavelength of 365 nm and an irradiation light power of about 200 μW on the recording medium as information recording light during information recording. The information recording light is light having a wavelength at which the ring-opened body of the diarylethene compound in the medium 94 has absorption.

The wavelength selection mirror 92 transmits a part of the light 91 a from the light source 91, reflects the light 97 a from the light source 97, and makes the light enter the condenser lens 93.

The condenser lens 93 can irradiate the optical recording medium 94 with the light from the wavelength selection mirror 92.

The condensing lens 95 allows the transmitted light 91b from the optical recording medium 94 to enter the light receiving portion of the photodiode 96.

The photodiode 96 includes a light amount detection circuit (not shown). Also, the photodiode 9
Numeral 6 can photoelectrically convert the light from the condenser lens 95 into an electric signal, and can detect a signal corresponding to the light intensity as a light amount by a light amount detection circuit (not shown).

The storage section 100 includes a rotation drive device (not shown), and can store a disk-shaped optical recording medium 94. The surface of the medium 94 is moved by the rotation driving device.

According to this optical recording apparatus, the light 97a is emitted from the light source 97 as information recording light when recording information. The light 97a from the light source 97 is transmitted to a wavelength selection mirror 92.
Is reflected by the optical recording medium 94 via the condenser lens 93.
Irradiated on top. In the recording layer 942 of the medium 94, when the diarylethene-based compound in the ring-opened state is irradiated with light having a wavelength that the ring-opened body has absorption as information recording light, in this example, light having a wavelength of 365 nm, Ring forms with different wavelengths of light absorption are produced. Thus, information is recorded on the medium 94.

In erasing information, a light source 91 emits light 91 a as information erasing light. Light 91 a from a light source 91 passes through a wavelength selection mirror 92 and is collected by a condenser lens 93.
Irradiates the optical recording medium 94 through the optical recording medium 94. In the recording layer 942 of the medium 94, when the diarylethene-based compound in a closed-ring state is irradiated with light having a wavelength at which the closed-ring has absorption as light for information erasing, in this example, light having a wavelength of 514 nm is irradiated with the original light. Return to ring-opened form. Thus, the information on the medium 94 is erased.

In reproducing information, light 91a is emitted from the light source 91 as information reproducing light. Light 91 a from a light source 91 passes through a wavelength selection mirror 92 and is irradiated onto an optical recording medium 94 via a condenser lens 93.

The transmitted light 91b from the optical recording medium 94 is incident on the photodiode 96 via the condenser lens 95. In the recording layer 942 of the medium 94, the light absorption spectrum is greatly different between the information unrecorded state, that is, the state of the ring-opened diarylethene compound, and the information recording state, that is, the state of the ring-closed body of the diarylethene compound. Information recording is performed by detecting the difference between the light absorption intensity in the open-ring state and the light absorption intensity in the closed-ring state at the wavelength of the information reproducing light (wavelength 514 nm in this case) at the photodiode 96. It is possible to read out the state or the information unrecorded state, that is, to reproduce the information.

According to the optical recording medium 94, since a diarylethene-based compound is employed as a photochromic material, it is excellent in repetitive durability and thermal irreversibility in recording, erasing, and reproducing information. The diarylethene-based compound is represented by the structural formulas (9), (10), (16),
It is a diarylethene compound represented by (17), and as described above, since the absorption band of the ring-opened body reaches near the visible region, the light having the absorption of the ring-opened body, that is, in the present example, is used for recording information. As light to be used, light in the vicinity of the visible region (in this example, light having a wavelength of 365 nm) can be employed. Accordingly, it is not necessary to use special optical components in the optical recording apparatus shown in FIG. 2 that accommodates the medium 94, and the cost of the optical recording apparatus can be reduced accordingly.

Next, performance evaluation experiments were performed on the photochromic material and the optical recording medium of the present invention, and these will be described below together with comparative experiments. For photochromic materials, measurement experiments of light absorption spectra were performed,
An optical recording experiment was performed on the optical recording medium. <Measurement Experiment of Light Absorption Spectra> In the experiment, the materials of Examples 1 to 4 were used as the photochromic materials 1 to 4 for the evaluation experiment, respectively.
2, 1,2-bis- (2
-Methylbenzothiophen-3-yl) perfluorocyclopentene, 1,2-bis- (2,4-dimethyl-5-phenylthiophen-3- represented by the following structural formula (19)
Il) A material consisting of perfluorocyclopentene was used.

[0083]

Embedded image

[0084]

Embedded image

With respect to the materials 1 to 4 for evaluation experiment and the materials 1 and 2 for comparative experiment, solutions were respectively dissolved in hexane. The experiments measured the light absorption spectra of these solutions. The molarity of each solution was adjusted to be approximately equal. The measurement was performed in a state where almost all of the diarylethene compound in the solution could be regarded as a ring-opened product.

The measurement results of the light absorption spectrum are shown in FIGS.
Shown in In FIG. 3, solid lines, broken lines, and chain lines show light absorption spectra of the ring-opened diarylethene compounds of the materials for evaluation experiments 1 and 2 and the material for comparative experiment 2 in a hexane solution, respectively. In FIG. 4, solid lines, broken lines, and chain lines indicate light absorption spectra of the ring-opened diarylethene compounds of the evaluation experimental materials 3 and 4 and the comparative experimental material 2 in a hexane solution, respectively. As shown in FIG. 3 and FIG. 4, the solutions of the materials for evaluation experiments 1 to 4 were
It can be seen that the ring-opened product has an absorption band up to a longer wavelength region.
Next, these solutions were irradiated with ultraviolet light of 308 nm from a mercury lamp, and the light absorption spectra were measured again. This ultraviolet light is light having a wavelength at which the ring-opened diarylethene compounds of the evaluation experiment materials 1 to 4 and the comparative experiment materials 1 and 2 all have absorption.

FIGS. 5 to 8 and 9 show the changes in the light absorption spectra of the solutions of the materials for evaluation experiments 1 to 4 and the solutions of the materials for comparison experiments 1 and 2 before and after irradiation with ultraviolet light. , Shown in FIG. Note that the solid line and the broken line in FIGS. 5 to 10 indicate the light absorption spectrum before irradiation with ultraviolet light and the light absorption spectrum after irradiation with ultraviolet light, respectively. In addition, the ring-opened diarylethene compound in each of the evaluation experiment materials 1 to 4 and the comparative experiment materials 1 and 2 is irradiated with light having a wavelength at which the ring-opened body has an absorption, so that the closed-chain state is obtained. FIGS. 11 to 14, FIGS. 15 and 16 show the state of the structural formula change due to the photochromic reaction generated by.

As shown in FIGS. 5 to 10, it can be seen that a new absorption band has been generated in the visible region due to ultraviolet light irradiation.
From this, the photochromic reactions shown in FIGS. 11 to 14, FIG. 15, and FIG. 16 proceed in the solutions of the evaluation experiment materials 1 to 4 and the solutions of the comparative experiment materials 1 and 2 by ultraviolet light irradiation, respectively. 11 to 14, 14, 15,
It can be seen that a closed body shown on the right side in FIG. 16 is produced. <Optical Recording Experiments> Using the diarylethene compounds of Examples 1 to 4, optical recording media were manufactured, and optical recording experiments described below were performed.

The optical recording medium used in the experiment was produced by the same method as that for producing the optical recording medium 94 shown in FIG.

That is, as an optical recording medium used in the experiment, as shown in FIG. 1, a recording layer 942 for recording information by coating a diarylethene compound and a polystyrene resin on a glass substrate 941 by spin coating. A recording layer 942 is formed by a spin coating method on a substrate 941 rotating at 3000 rpm using 2.5 parts by weight of a diarylethene compound, 2.5 parts by weight of a polystyrene resin, and 95 parts by weight of toluene as a coating liquid. What was used was used. Optical recording media prepared using the diarylethene compounds of Examples 1 to 4 were used as optical recording media for evaluation experiments 1 to 4, respectively. The thickness of each of the recording layers 942 was about 150 nm. In addition, the recording layer 942 in the optical recording medium after the production is colorless, and almost all of the diarylethene-based compound in the recording layer 942 can be regarded as a ring-opened product. In this optical recording experiment, the optical recording media for evaluation experiments 1 to 4 were respectively housed in the optical recording device shown in FIG. 1) The initial state, that is, the light 91a having a wavelength of 514 nm is irradiated from the light source 91 to the optical recording medium 94 having the colorless recording layer 942, and the intensity 96 of the light 91b transmitted through the optical recording medium by the photodiode 96 is measured. did. At this time, the irradiation light power of the light 91a from the light source 91 was about 10 μW on the optical recording medium. 2) Wavelength 365 from light source 97 to optical recording medium 94
Irradiated with light 97a of nm. This process is referred to as a recording process. At this time, the irradiation light power of the light 97a from the light source 97 was about 200 μW on the optical recording medium, and the irradiation time was 1 msec. 3) The transmitted light intensity T2 during recording was measured in the same manner as in 1) above. 4) Wavelength 514 from light source 91 to optical recording medium 94
Irradiated with light 91a of nm. This process is called an erasing process. At this time, the irradiation light power of the light 91a from the light source 91 was about 1 mW on the optical recording medium, and the irradiation time was 1 msec. 5) The transmitted light intensity T3 at the time of erasing was measured in the same manner as in 1). 6) Thereafter, the above operations 1) to 5) were repeated to measure transmitted light intensities T4 to T10. That is, the transmitted light intensities T4, T6, T8, and T10 during recording and the transmitted light intensities T5, T7, and T9 during erasure were measured. The light intensity was adjusted using the ND filters 91 'and 97'.

FIG. 17 shows the results of the optical recording experiment.

FIG. 17 is a graph showing the results of an optical recording experiment using the optical recording media 1 to 4 for evaluation experiments.
This is a graph obtained by plotting the ratio of transmitted light intensity T1 (transmitted light intensity in the initial state of the medium) for each of 1 to T10 and connecting the plots with lines. The solid line in the figure,
The broken line, the chain line, and the one-dot chain line show the experimental results using the optical recording media for evaluation experiments 1 to 4, respectively.

According to this experiment, the optical recording medium for evaluation experiment 1
It can be seen that the recording and erasing of information can be repeated for any of the media Nos. 1 to 4.

[0094]

As described above, according to the present invention, a photochromic material comprising a diarylethene-based compound, which is convenient for use as a recording material, has an absorption band of a ring-opened body near the visible region. Photochromic materials can be provided.

According to the present invention, there is provided an optical recording medium for performing at least one of recording, reproducing and erasing of information by light using a photochromic material.
It is possible to provide an optical recording medium which is excellent in repetitive durability and thermal irreversibility in erasing and reproducing, and which can reduce the production cost of the medium and the cost of an optical recording apparatus for containing the medium.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a schematic configuration of a part of an example of an optical recording medium manufactured using a photochromic material comprising a diarylethene-based compound of Examples 1 to 4.

FIG. 2 is a side view of a schematic configuration of an example of an optical recording device that accommodates the optical recording medium shown in FIG. 1 and records, erases, and reproduces information on the medium.

FIG. 3 shows materials for evaluation experiments 1 and 2 in a hexane solution.
4 is a graph showing the measurement results of a light absorption spectrum in a ring-opened state of a diarylethene-based compound of Comparative Experiment Material 1.

FIG. 4 shows evaluation test materials 3 and 4 in a hexane solution.
6 is a graph showing the measurement results of a light absorption spectrum of a ring-opened form of a diarylethene-based compound of Comparative Experiment Material 2.

FIG. 5 is a graph showing the measurement results of light absorption spectra of a diarylethene-based compound of Evaluation Material 1 in a hexane solution before and after irradiation with ultraviolet light.

FIG. 6 is a graph showing the measurement results of the light absorption spectrum of a diarylethene compound of Evaluation Material 2 in a hexane solution before and after irradiation with ultraviolet light.

FIG. 7 is a graph showing the results of measuring the light absorption spectrum of a diarylethene compound of Evaluation Material 3 in a hexane solution before and after irradiation with ultraviolet light.

FIG. 8 is a graph showing the measurement results of a light absorption spectrum of a diarylethene-based compound of Evaluation Experiment Material 4 before and after irradiation with ultraviolet light in a hexane solution.

FIG. 9 is a graph showing the measurement results of light absorption spectra of a diarylethene compound of Comparative Experimental Material 1 before and after irradiation with ultraviolet light in a hexane solution.

FIG. 10 is a graph showing the measurement results of the light absorption spectrum of a diarylethene compound of Comparative Experiment Material 2 before and after irradiation with ultraviolet light in a hexane solution.

FIG. 11 is a structural formula based on a photochromic reaction in which a ring-opened body is irradiated with light having a wavelength at which the ring-opened body absorbs a diarylethene-based compound in the ring-opened state in the evaluation experimental material 1; It is a figure showing a state of change.

FIG. 12 is a structural formula based on a photochromic reaction in which a ring-opened state is generated by irradiating a light of a wavelength at which the ring-opened body has absorption to a diarylethene-based compound in a ring-opened state in a material 2 for evaluation experiment. It is a figure showing a state of change.

FIG. 13 is a structural formula based on a photochromic reaction in which a ring-opened body is irradiated with light having a wavelength at which the ring-opened body absorbs a diarylethene-based compound in a material 3 for evaluation experiment, which is in an open-ring state. It is a figure showing a state of change.

FIG. 14 is a structural formula based on a photochromic reaction in which a ring-opened body is irradiated with light having a wavelength that the ring-opened body absorbs to a ring-opened diarylethene compound in the evaluation experiment material 4; It is a figure showing a state of change.

FIG. 15 is a structural formula based on a photochromic reaction in which a ring-opened body is irradiated with light having a wavelength that the ring-opened body absorbs to a ring-opened diarylethene-based compound in Comparative Experiment Material 1. It is a figure showing a state of change.

FIG. 16 is a structural formula based on a photochromic reaction in which a ring-opened body is irradiated with light having a wavelength that the ring-opened body absorbs to a ring-opened diarylethene compound in Comparative Experiment Material 2; It is a figure showing a state of change.

FIG. 17 is a graph showing the results of an optical recording experiment using the optical recording media for evaluation experiments 1 to 4, and shows transmitted light intensities T1 to T1.
The graph plots the ratio of transmitted light intensity T1 (transmitted light intensity in the initial state of the medium) for each of 0, and connects the plots with lines.

[Explanation of symbols]

 Reference Signs List 91 Light source for information erasing and reproduction 91 'ND filter 91a Light for information erasing or light for information reproduction 91b Transmitted light from optical recording medium 94 Wavelength selection mirror 93, 95 Condensing lens 94 Optical recording medium 941 Glass substrate 942 Recording layer 96 Photodiode 97 Information recording light source 97 ′ ND filter 97a Information recording light 100 Optical recording medium housing

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kazuyuki Ogura, Inventor Kazuki Ogura 2-3-1-13, Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. 2-3-1-3 Osaka International Building Minolta Co., Ltd. (72) Inventor Masahiro Irie 4-24-25-706 Muromi, Sawara-ku, Fukuoka F-term (reference) 2H123 AA00 AA08 5D029 JA04 JC04 JC20 VA03 5D121 AA01 EE22

Claims (2)

[Claims] 1. A photochromic material comprising a diarylethene compound, wherein the diarylethene compound is a compound represented by the following general formula (1). Embedded image (In the formula (1), R1 represents an alkyl group which may be substituted or an alkoxy group which may be substituted;
To R7 each represent a hydrogen atom, an alkyl group which may be substituted, an alkoxy group which may be substituted, or an aryl group which may be substituted. A is represented by the following general formula (2): Or the following general formula (3): Represents a group represented by In the formula, R11 and R14 represent an optionally substituted alkyl group or an optionally substituted alkoxy group, and R12, R13, and R15 to R18 each represent a hydrogen atom or an optionally substituted alkyl group, or a substituted Represents an optionally substituted alkoxy group or an optionally substituted aryl group. ) 2. An optical recording medium for performing at least one of recording, reproduction and erasing of information by light using a photochromic material, wherein the optical recording medium contains the photochromic material according to claim 1. Medium.