JP2001151769A - Photochromic compound and optical functional element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a photochromic compound undispersible in a polymer resin medium, capable of forming an amorphous thin film by the photochromic compound alone, having sensitivity in a semiconductor laser wavelength range and an optical functional element using the photochromic compound. SOLUTION: This photochromic compound is represented by formula (1) or formula (2) (R1, R2, R3, R4, R5, R6, R7 and R8 are each H or an alkyl group; RA is an aromatic ring or a heterocyclic ring; X is an oxygen atom, a sulfur atom or a nitrogen atom; ring A is an aliphatic ring, an acid anhydride or maleimide group; ring B and ring C each may be nonsubstituted or partially substituted; and (n) is 1 or 2). A thin film comprising the photochromic compound is irradiated with light rays to give an optical functional element so as to record information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel photochromic compound and an optical functional device using the same.

[0002]

2. Description of the Related Art Photochromic compounds are:
A material containing molecules or molecular aggregates that reversibly produce two isomers in different states by light irradiation. The molecular structure is changed by the photochemical reaction, and the light absorption coefficient, refractive index, It has the property of reversibly changing optical properties such as optical rotation or dielectric constant. By utilizing the difference between these optical characteristics, information can be recorded / reproduced. Also, by restoring the molecular structure, information can be erased.

The reversible photoisomerization reaction of a photochromic compound is briefly represented by the following formulas (F1) and (F2).

A (λ1) → B (λ2) (F1) B (λ2) → A (λ1) (F2) Here, A (λ1) and B (λ2) are absorption spectra, respectively. Are different isomers. Formula (F1) shows an isomerization reaction by irradiation with wavelength λ1, and formula (F2) shows an isomerization reaction by irradiation with light of λ2.

When a photochromic compound is used as an optical recording medium, data can be recorded using light of one of the wavelengths λ1 and λ2 as recording light. The recorded data can be read out (reproduced) by absorption, and can be erased by irradiation with light of the other wavelength.

Normally, data is read out based on a difference in absorbance between isomers, that is, a change in transmittance as described above. The greater the difference in absorbance, the better the reproduced signal, that is, the higher the C / N ratio. Although data is read out due to the difference in absorbance, the photochromic reaction itself does not have a threshold value, so that data is destroyed during reproduction by this method, and data cannot be read out many times. Therefore, non-destructive reading of data is one of the problems of the photochromic optical memory.

There are roughly two methods for achieving non-destructive readout. One is the development of photochromic compounds that have a threshold for photoreaction and compounds in which three isomers react. Another method is to read data without absorption. For example, light having a wavelength at which a photochromic reaction is not induced is used as read light, and read using phase contrast (refractive index change).

The photochromic compound has a photorefractive effect in which the refractive index is reversibly changed by light irradiation, so that the photochromic compound can be applied to an optical memory by utilizing this effect, and a bit recorded on a medium by a photochromic reaction. The data can be read as a refractive index difference.

The photorefractive effect, in which the refractive index is reversibly changed by light irradiation, is a phenomenon that has attracted attention in recent years, and is expected to be applied to optical memory devices and optical switching devices.

Conventionally, the photorefractive phenomenon has been described as strontium barium niobate (SrxBa1-xNb2O6).
) And lithium niobate (LiNbO3). When an electric field is applied, the refractive index changes greatly, the changed refractive index is stably maintained, and when light irradiation is performed with another pattern, the initial pattern is erased and a new pattern is formed, so-called It shows a reversible refractive index change. In recent years, similar effects have been reported for organic substances, and the characteristic is that the change in refractive index is several times to several tens times larger than that of inorganic substances.

Recently, it has been proposed to use a photochromic compound as a photorefractive organic material. The photochromic compound has an advantage that the refractive index changes only by irradiating light, and the refractive index can be maintained in a changed state without consuming energy even after the change in the refractive index. Furthermore, the refractive index change width in the colored / decolored state is large, and has a feature that it is several hundred times as large as that of a conventional photorefractive material.

Such a property is very effective not only for an optical memory but also for an optical switching element. In particular, when used in an optical switching element, the change in the refractive index is large, so that the element can be downsized. Further, since control by light is possible, remote control using light can be performed, which is very effective.

When a photochromic compound is applied to an optical functional element such as an optical recording medium, it is necessary to form a thin film containing the photochromic compound. Heretofore, as a thin film forming method, a method of dispersing a photochromic compound in a polymer matrix such as polymethyl methacrylate or polystyrene has been generally used.

However, it is known that the higher the concentration of the photochromic material, the lower the conversion ratio, and the maximum value is reached at a concentration of about 30 parts by weight with respect to 100 parts by weight of the polymer. Further, some photochromic compounds have poor compatibility with polymers and poor dispersibility. As a result, sufficient characteristics have not been obtained so far.

The photochromic compound has a wavelength of 305 nm.
Colored by the following ultraviolet light (ring-closing reaction) and returned to the original (colorless) by visible light of 450 nm or more (ring-opening reaction)
Therefore, it is necessary to use ultraviolet light in any of writing, erasing, and reproducing.

However, since a semiconductor laser of 400 nm or less has not been developed at present, a large-scale ultraviolet laser is required, which is not practical. Therefore, development of a photochromic material having sensitivity in a semiconductor laser wavelength region has been desired.

On the other hand, in view of such a situation, a diarylethene compound having photochromic properties in a crystalline state has been obtained (see M. Irie, Chem. Lett. 899 (1995), JP-A-8-1199633). .

A diarylethene compound having a photochromic property in a crystalline state has an advantage that a photochromic thin film having high absorbance can be formed by vapor deposition or the like without being dispersed in a polymer resin.

However, the crystal film made of the photochromic compound has to be formed by a vacuum evaporation method or the like, and has a drawback that it is inferior in mass productivity.

The present invention has been made in view of the above-described problems, and has as its object to form an amorphous thin film using a photochromic compound alone without being dispersed in a polymer resin medium, and to provide a semiconductor laser in the wavelength region. An object of the present invention is to provide a photochromic compound having sensitivity and an excellent optical functional device using the same.

[0021]

In order to achieve the above object, the photochromic compound of the present invention is a photochromic compound represented by the formula (1) shown in FIG. 1 or the formula (2) shown in FIG.

(Where R1, R2, R3, R
4, R5, R6, R7, and R8 each represent hydrogen or an alkyl group; RA represents an aromatic ring or a heterocyclic ring; and even though R1 to R8 and RA are the same as each other,
They may be different (that is, for example, include cases where R1 is different from each other), and may be unsubstituted or partially substituted. Note that the substituent is an alkyl group, an aryl group, a halogen group, a nitro group, an amino group, an alkoxy group, a cyano group, or the like.

X is an oxygen atom, a sulfur atom or a nitrogen atom.

Ring A is an aliphatic ring, an acid anhydride or a maleimide group, and rings B and C may be unsubstituted or partially substituted. As the substituent, an alkyl group,
An aryl group, a halogen group, a nitro group, an amino group, an alkoxy group, and a cyano group. The integer n is 1 or 2. )
Further, an optical functional element is provided, in which information is recorded by irradiating light to a thin film made of the photochromic compound.

The photochromic compound specifically has a diarylethene skeleton, further has a conjugated double bond chain on a heterocycle in the diarylethene skeleton, and a triarylamino group at the end of the conjugated double bond chain. Substitution is a feature of the chemical structure. Thus, the photochromic compound of the present invention having a diarylethene skeleton exhibits a thermo-irreversible photochromic reaction, and furthermore, both the colored state and the decolored state are thermally stable,
Moreover, it has the feature of being excellent in repeated durability.

Further, by introducing a conjugated double bond chain into the molecule, the conjugated system in the molecule is expanded, the absorption maximum wavelength of the colorless body (ring-opened body) is lengthened, and a blue semiconductor laser having an oscillation wavelength of 400 nm is obtained. It has the feature that sensitivity is imparted.

Furthermore, since the terminal of the conjugated double bond is substituted with a triarylamino group, it is possible to form a stable glassy state while having a low molecular weight. As a result, the photochromic compound of the present invention is capable of forming an amorphous thin film by itself and has a characteristic of exhibiting a reversible photochromic reaction similarly to a solution system. Thus, a photochromic thin film having a large change in absorbance can be provided.

The amorphous thin film comprising the photochromic compound of the present invention is not dispersed in a matrix such as a polymer and is in a single state like a conventional crystalline film. Shows a larger absorbance change. The amorphous thin film of the photochromic compound does not require a large-scale apparatus such as a vacuum evaporation method required for forming a crystal film, and can be formed by a coating method such as a spin coating method.

As described above, the optical functional device of the present invention
Since it has a recording layer made of a photochromic compound exhibiting excellent optical characteristics, a high C / N ratio can be obtained.

[0030]

Embodiments of the present invention will be described below in detail.

Equation (1) shown in FIG. 1 or (2) shown in FIG.
The photochromic compound of the present invention represented by the following formula (1) can be produced, for example, by the method shown in FIGS. However, the manufacturing method is not limited to this,
It can be produced by appropriately selecting from known methods.

That is, as shown on the left side of the reaction formula in FIG. 3 (a), a heterocyclic compound is reacted with butyllithium and then with an iodine compound (RI), whereby the alkyl shown on the right side of the reaction formula is obtained. A group-substituted heterocyclic compound is synthesized.

Next, as shown in FIG. 3 (b), by reacting an alkyl group-substituted heterocyclic compound with bromine,
A heterocyclic compound into which two atoms of bromine have been introduced is synthesized.

Next, as shown in FIG. 3C, the bromine-substituted heterocyclic compound is reacted with zinc chloride to synthesize a zinc compound. Then, the zinc compound is added to a solution in which the iodinated amine compound and the palladium metal catalyst are mixed and reacted. As a result, a heterocyclic compound substituted with an amino group is synthesized as shown on the right side of FIG.

Thereafter, as shown in FIG.
The heterocyclic compound substituted with an amino group obtained in (c) is reacted with butyllithium to generate anionic species by lithium-halogen exchange. This anion species has a ring A
By reacting the compound (halogen atom substitution),
The target diarylethene shown on the right side of FIG. 3D can be synthesized.

Here, in each formula, R1, R2, R3, R4
R5, R6, R7 and R8 each represent hydrogen or an alkyl group, which may be the same or different from each other. RA represents an aromatic ring or a heterocyclic ring, and may be the same or different from each other. In addition, these R1
R8 and RA may be unsubstituted or partially substituted. Substituents include alkyl, aryl, halogen, nitro, amino, alkoxy, cyano.

X represents an oxygen, sulfur, or nitrogen atom. Of these, a sulfur atom is particularly preferred. Ring A is an aliphatic ring, an acid anhydride, or a maleimide group. Also, ring B, ring C,
Ring D may be unsubstituted or partially substituted. As the substituent, alkyl, aryl, halogen, nitro,
There are amino, alkoxy and cyano.

Since the photochromic compound of the present invention has a triarylamino group substituted at the end of the conjugated double bond chain, the crystallization rate is suppressed, and as a result, a low molecular weight, stable glass state (amorphous state) is obtained. ). Therefore, the photochromic compound can form an amorphous thin film by itself, and exhibits a reversible photochromic reaction similarly to the solution system.

Since the photochromic thin film comprising the photochromic compound of the present invention is an amorphous thin film composed of a single photochromic compound, unlike a polymer resin dispersed film, it has excellent optical characteristics such as a large change in absorbance and a change in refractive index. Having.

Further, since the photochromic compound of the present invention has a conjugated double bond chain introduced into the molecule, the conjugated system in the molecule is expanded, and the absorption maximum wavelength of the colorless body (ring-opened body) is increased. It has a longer wavelength and is sensitive to a blue semiconductor laser with an oscillation wavelength of 400 nm.

Further, the photochromic thin film comprising the photochromic compound of the present invention can be applied to a coating method (spin coating method, bar coating method, immersion method) generally used for forming an organic thin film without using a large-scale apparatus such as vacuum evaporation. Method, melt extrusion method, spray method, etc.). Specifically, a thin film can be formed by dissolving the photochromic compound in a highly viscous organic solvent, applying the solution, and further performing heat treatment at about 80 to 150 ° C.

The photochromic thin film obtained by the above method can be used for an optical functional element such as an optical recording medium.
As shown in a schematic cross-sectional view in FIG. 4, an optical recording medium P1, which is an optical functional element of the present invention, is formed on a disk-shaped substrate 1 made of, for example, a resin material such as polycarbonate having translucency or glass. Further, a thin film made of a photochromic body produced by the method of the present invention is provided as a recording layer 2, and a reflective layer 3 is further provided thereon.

The substrate 1 constituting the optical recording medium P1 is
Translucent plastics (for example, polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin), glass, ceramics, and metal can be used. The recording layer 2 has a thickness of 100
Laminated to a thickness of about 5 to 5 μm (preferably 1000 to 1 μm), and a metal (Au, Al, Ag, Cu, Cr, Ni, etc.) or a semi-metal (Si, etc.) which is highly reflective and hardly corroded by an evaporation method or the like )
The reflective layer 3 is formed to have a thickness of about 50 to 3000 (preferably 100 to 3000).

If the thickness of the recording layer 2 is less than the above range, no photosensitivity is obtained, and if it is too large, the photoreaction speed decreases in the thickness direction, which is not preferable. In the case of the reflective layer 3, if the thickness is too thin, the reflectance cannot be obtained.

According to the optical recording medium P1 configured as described above, information can be recorded by the light L1 incident from the substrate 1,
Information can be read by detecting the reflected light L2.

When an opaque material is used for the substrate 1, a reflective layer 3 is provided on the substrate 1 like the optical recording medium P2 shown in FIG. And the light L1 may be irradiated from the recording layer 2 side. In addition, these layer configurations are the minimum required configurations, and for example, a reflective layer or a recording layer may be covered with a protective layer to form a multi-layer configuration. Thus, it is possible to obtain an optical recording medium P2 having a large change in reflectance and a good durability against repeated coloring and decoloring.

In addition to the above-described arrangement of the laminated body composed of the recording layer and the reflective layer on the substrate, similarly to the optical recording medium P3 shown in FIG. A recording layer 2 may be provided on the recording medium, information may be recorded by the incident light L1, and the information may be reproduced based on a difference in light reflectance by detecting the incident light L1 and the outgoing light L2. Also in this case, the recording layer 2 may be covered with a light-transmitting protective layer or the like to form a multi-layer structure.

Similarly, the optical recording medium P shown in FIG.
4, it is also possible to use the change in the refractive index.
That is, when information is recorded, as shown in FIG. 8A, for example, a He-Cd laser having a wavelength of 442 nm or a wavelength of 633 nm is used.
The recording light is irradiated to the recording layer 2 through the beam splitter 21 and the mirrors 22a and 22b using the writing light 23 of He-Ne laser of m m to change the refractive index of the recording layer 2 to record information. In reproducing information, as shown in FIG.
For example, using the reading light 24 having a wavelength of 830 nm, the mirror 2
The information is reproduced by irradiating the recording layer 2 via 2a and detecting it with the detector 25.

In the embodiment of the present invention, a conjugated double bond chain is provided on the heterocycle in the diarylethene skeleton represented by the formula (1) in FIG. 1 or the formula (2) in FIG. Although a photochromic compound in which a triarylamino group is substituted at the end of a bonding chain and a case where an amorphous photochromic thin film composed of the photochromic compound is applied to an optical recording medium have been described, the present invention is not limited to this. It can be applied to elements, light modulating materials, optical sensors, and the like. Further, the substrate on which the photochromic thin film is formed is not limited to the above-described materials, and can be appropriately changed without departing from the scope of the invention.

[0050]

The present invention will be described below in more detail with reference to examples. The present invention is not limited to the following embodiments unless departing from the gist of the present invention.

Example 1 A photochromic compound represented by the formula (3) in FIG. 9 was synthesized as follows.

(1) Synthesis of 2,4-dimethylthiophene (Formula (4) in FIG. 10) 25.5 g (0.26 g) of 3-methylthiophene was placed in a 300 ml three-necked flask.
mol), 125 ml of dry ether and 33.2 g of TMEDA (tetramethylethylenediamine), and the reaction system was cooled to 0 ° C. To this reaction solution, 204 ml of a normal butyllithium / hexane solution was slowly added dropwise at 0 ° C. for 1 hour.
The mixture was further stirred at room temperature for 2 hours. Then, 17.5 ml of methyl iodide was added thereto again while cooling with ice, and the mixture was stirred at 0 ° C. for 2 hours and further at room temperature for 3 hours. After completion of the stirring, water was added to separate an organic layer and an aqueous layer, and the aqueous layer was extracted with ether. The organic layer was washed with dilute hydrochloric acid and further with water, and then dried over anhydrous magnesium sulfate. After removing magnesium sulfate with a glass filter, the solvent was distilled off under reduced pressure, and the obtained liquid was purified by silica gel column chromatography and distilled under reduced pressure to obtain 2,4-dimethylthiophene as a colorless liquid (the above chemical reaction formula was used). FIG. 10).

(2) Synthesis of 2,4-dibromo-3,5-dimethylthiophene (Formula (5) in FIG. 11) 11.2 g of 2,4-dimethylthiophene in a 500 ml three-necked flask
(0.1mol), 400ml of acetic acid
32 g (0.2 mol) of bromine were added dropwise. After stirring at room temperature for 20 hours, the mixture was neutralized with sodium thiosulfate and sodium carbonate, and extracted with ether. The organic layer was washed with water and dried over anhydrous magnesium sulfate. Then, after removing magnesium sulfate with a glass filter, the solvent was distilled off under reduced pressure, and the obtained liquid was purified by silica gel column chromatography and distilled under reduced pressure to obtain 2,4-dibromo-3,5-colorless liquid.
Dimethylthiophene was obtained (the chemical reaction formula is shown in FIG. 11).

(3) Synthesis of Formula (6) in FIG. 12 54.2 g (0.2 mol) of 2,4-dibromo-3,5-dimethylthiophene in a 500 ml three-necked flask, 200 ml of dry ethyl ether
, 22.5 g (0.22 mol) of TMEDA and 157 ml of a normal butyl lithium / hexane solution (1.
4M, 0.22 mol) and stirred at room temperature for 2 hours.

Two hours later, 200 ml (0.2 mol of zinc chloride) of a zinc chloride / ether solution was added to the reaction system at room temperature, and the mixture was further stirred at room temperature for 5 hours (reaction solution A). Then another 500m
l A three-necked flask was charged with 85 g (0.2 mol) of iodide, 2.31 g of tetrakis (triphenylphosphine) palladium, and 200 ml of dry tetrahydrofuran, and stirred at room temperature for 4 hours. After 4 hours, the previously prepared reaction solution A was added dropwise to this reaction solution at room temperature. After the completion of the dropwise addition, the reaction system was heated to 50 ° C. and stirred at 50 ° C. for 15 hours.

After completion of the stirring, water was added to separate an organic layer and an aqueous layer, and the aqueous layer was extracted with ether. The organic layer was washed with dilute hydrochloric acid and further with water, and then dried over anhydrous magnesium sulfate. After removing magnesium sulfate with a glass filter, the solvent was distilled off under reduced pressure, and the obtained liquid was purified by silica gel column chromatography to obtain the target compound as a colorless liquid represented by the formula (6) in FIG. 12 ( The above chemical reaction formula is shown in FIG. 12).

(4) Synthesis of photochromic compound (FIG. 9, formula (3)) In a 500 ml three-necked flask, compound 4 of formula (6) in FIG.
1.93 g (0.07 mol) and 150 ml of dry tetrahydrofuran were added, and the reaction system was cooled with a dry ice / methanol bath. To this reaction solution, 75 ml (0.105 mol) of a normal butyllithium / hexane solution was slowly added dropwise, and the mixture was stirred at -78 ° C for 1 hour. Next, 4.03 ml (0.03 m
ol) of perfluorocyclopentene, and the mixture was stirred at 0 ° C. for 7 hours. After completion of the stirring, water was added to separate an organic layer and an aqueous layer, and the aqueous layer was extracted with ether. The organic layer was washed with dilute hydrochloric acid and further with water, and then dried over anhydrous magnesium sulfate. After removing magnesium sulfate with a glass filter, the solvent was distilled off under reduced pressure, and the obtained liquid was purified by silica gel column chromatography to obtain the target compound as a white solid represented by the formula (3) in FIG. (The above chemical reaction formula is shown in FIG. 13.) The structure of the obtained four compounds (formulas (3) to (6)) was analyzed by 1 H-NMR, 13 C-NMR, FT-IR, and GC / MS. As a result, it was confirmed that all the compounds were target products.

When the absorption spectrum of the obtained photochromic compound (formula (3)) was measured, it was found to have a maximum wavelength at 353 nm as shown in FIG. However, since the absorption band extends to about 450 nm, the blue laser also has absorption near the long region of 400 nm. Further, when this compound (formula (3)) was irradiated with ultraviolet light having a wavelength of 350 nm, the solution was colored and its absorption maximum was 635 nm.
Observed nearby. Then, it was confirmed that the change in the absorption wavelength due to this light irradiation occurred reversibly (the reversible reaction of this compound is shown in FIG. 15). The downward reaction in the figure occurs with high efficiency around the wavelength of 400 nm, and the upward reaction in the figure occurs with high efficiency at the wavelength of 600 to 700 nm.

Further, it was confirmed that the crystal of the formula (3) obtained by recrystallization melted at 200 ° C. to become an isotropic liquid, and when this was cooled to room temperature, a transparent and stable glass was produced. . When the temperature of the glass sample was raised again, 106
A glass transition phenomenon was observed at ℃.

Example 2 After dissolving the photochromic compound (formula (3)) obtained in [Example 1] in toluene, the solution was applied on a quartz substrate by spin coating and baked at 80 ° C. Thus, a photochromic thin film (thin film 1) was produced (film thickness 0.2 μm). Generally, an organic thin film
It has a strong tendency to crystallize, and if left for a long period of time, it will crystallize, and the crystallized portion will become a defect, causing deterioration in characteristics. However, it was confirmed that the thin film 1 was free from defects due to crystallization even after being left for 3 months or longer, and that no deterioration in characteristics was observed.

When the obtained thin film 1 was subjected to XRD measurement and observation with a polarizing microscope, only a broad halo was observed in the XRD measurement. It was confirmed that it was a uniform amorphous thin film.

Further, the obtained amorphous thin film is used in a dark place.
It was stable without deterioration of characteristics for 900 hours at 80 ° C. In addition, even in the repetition of coloring and decoloring, even after the repetition of 10,000 times or more, almost no deterioration in characteristics was observed.

Example 3 Using the photochromic thin film obtained in Example 2, an optical recording medium P1 shown in FIG. 4 was manufactured. A recording layer composed of the photochromic compound (formula (3)) obtained in [Example 1] was laminated on a translucent polycarbonate substrate, and a reflective layer composed of an Al layer was laminated thereon. Further, a protective layer made of an acrylic resin was formed thereon, thereby producing an optical recording medium.

After irradiating the entire surface of the optical recording medium with ultraviolet light to bring the photochromic compound in the recording layer into a colored state, evaluation of recording / reproduction is performed using a device equipped with a semiconductor laser of 400 nm and 680 nm in a pickup. Was. 400n
m Recording with a laser power of 10mW, 680nm laser 0.2m
When playback was performed with the power of W, the C /
A reproduction signal of N ratio was obtained.

Example 4 The change in the refractive index before and after light irradiation was examined using the photochromic thin film obtained in Example 2, and the difference in the refractive index between the colorless state and the photosteady state was 6 × 10 ^−. It turned out to be ² .

Example 5 Using the photochromic thin film obtained in [Example 2], an optical recording medium P4 shown in FIG. 7 was produced, and a He-Cd laser (442 nm) was used as a recording light, and data was recorded on the photochromic thin film. Was recorded. The recorded data could be read out as a difference in refractive index with a semiconductor laser (830 nm).

[0067]

As described in detail above, the photochromic compound of the present invention has a diarylethene skeleton, and further has a conjugated double bond chain on a heterocycle in the diarylethene skeleton. Since a triarylamino group is substituted at the chain end, it is possible to form an amorphous thin film with a photochromic compound alone and to provide a photochromic thin film having excellent optical characteristics because of exhibiting semiconductor laser wavelength sensitivity. Can be.

Further, the effect of the conjugated double bond chain of the above-mentioned compound expands the conjugated system in the molecule, and the absorption maximum wavelength of the colorless body (ring-opened body) becomes longer.
m semiconductor laser sensitivity.

In addition, in forming a thin film, a large-scale apparatus such as a vacuum evaporation method is not required, and the film can be formed by a simple coating method such as a spin coating method, so that productivity can be improved.

Further, when the photochromic thin film of the present invention is used for a recording layer, it is possible to provide an optical recording medium having excellent repetition durability and excellent optical characteristics.

Since the change in absorbance and the change in refractive index before and after light irradiation are much larger than those of a conventional polymer resin dispersion film, an excellent optical recording medium can be provided.

[Brief description of the drawings]

FIG. 1 is a chemical formula of a photochromic compound according to the present invention.

FIG. 2 is a chemical formula of a photochromic compound according to the present invention.

FIGS. 3A to 3D are chemical reaction formulas of the photochromic compound according to the present invention, respectively.

FIG. 4 is a schematic cross-sectional view schematically illustrating an optical recording medium P1 of the present invention.

FIG. 5 is a schematic cross-sectional view schematically illustrating an optical recording medium P2 of the present invention.

FIG. 6 is a schematic sectional view schematically illustrating an optical recording medium P3 of the present invention.

FIG. 7 is a schematic sectional view schematically illustrating an optical recording medium P4 of the present invention.

FIGS. 8A and 8B are schematic diagrams each showing a schematic configuration of an optical recording system using a change in refractive index.

FIG. 9 is a chemical formula of a photochromic compound according to the present invention.

FIG. 10 is a chemical reaction formula for obtaining a photochromic compound according to the present invention.

FIG. 11 is a chemical reaction formula for obtaining a photochromic compound according to the present invention.

FIG. 12 is a chemical reaction formula for obtaining a photochromic compound according to the present invention.

FIG. 13 is a chemical reaction formula for obtaining a photochromic compound according to the present invention.

FIG. 14 is a diagram showing a change in absorbance of the photochromic compound according to the present invention before and after light irradiation.

FIG. 15 is a formula showing a reversible change of a photochromic compound according to the present invention by light irradiation.

[Explanation of symbols]

 1: substrate 2: recording layer 3: reflective layer 21: beam splitters 22a, 21b: mirror 23: write light 24: read light 25: detector P1, P2, P3, P4: optical recording medium L1: incident light L2: output Glow

Claims (2)

[Claims] 1. A photochromic compound represented by the following formula (1) or (2). Embedded image Embedded image (Where R1, R2, R3, R4, R5, R
6, R7 and R8 are each a hydrogen or an alkyl group, and RA is
An aromatic ring or a heterocyclic ring includes those having a substituent in part. X is an oxygen atom, a sulfur atom or a nitrogen atom. Ring A is an aliphatic ring, an acid anhydride, or a maleimide group, and Ring B and Ring C include those having a substituent in part. The integer n is 1 or 2. ) 2. An optical functional device wherein information is recorded by irradiating light to a thin film made of the photochromic compound according to claim 1.