JP2001064276A - Photochromic compound and photofunctional element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new photochromic compound capable of forming by itself amorphous thin film which is excellent in repeated durability and great in both absorbance and refractive index changes between points before and after light irradiation, therefore affording excellent photorecording elements. SOLUTION: This new photochromic compound is represented by formula (R1 and R2 are each H or an alkyl; RA is an aromatic ring or a heterocyclic ring; X is O, S or N; ring A is an aliphatic ring, an acid anhydride or maleimide; (n) is an integer of 1-3) or formula II, e.g. a compound of formula III. This new compound is obtained, for example, by the following steps: 2,4- dimethylthiophene as starting material is reacted with zinc chloride followed by 4-iodo-tetraphenylmethane in the presence of (triphenylphosphine) palladium to form 2,4-dimethyl-5-[4-(triphenylmethyl)phenyl]thiophene, and then to which iodine and an aqueous iodic acid solution are added to substitute the heterocyclic ring's 3-position with iodine atom followed by reacting the resultant product with perfluorocyclopentene to be represented as the ring A in formulae I and II.

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 that contains molecules or molecular aggregates that reversibly generate two isomers in different states by light irradiation. The molecular structure is changed by a 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) A (λ1) and B (λ2) are different isomers having different absorption spectra. Show body. 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 by using light having 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.

Normally, data is read out due to a difference in absorbance. However, since the photochromic reaction itself does not have a threshold value, this method causes data destruction during reproduction, 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 ways to achieve non-destructive reading. 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, and can be applied to an optical memory utilizing this effect. Bit data recorded on a medium by a photochromic reaction can be read as a difference in refractive index.

The photorefractive effect, in which the refractive index is reversibly changed by light irradiation, has been attracting attention in recent years, and is expected to be applied to optical memory elements and optical switching elements.

The conventional photorefractive phenomenon is strontium barium niobate (SrxBa1-xNb2O6)
And inorganic substances such as lithium niobate (LiNbO3). When an electric field is applied, the refractive index changes greatly,
When the changed refractive index is stably held and light irradiation is performed with another pattern, the initial pattern is erased and a new pattern is formed, which indicates a reversible refractive index change. In recent years, similar effects have been reported for organic substances. In the case of organic substances, the change in refractive index is characterized by being 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 for an optical switching element, the change in the refractive index is large, so that the element can be downsized. Furthermore, since control by light is possible, remote control using light is also possible, 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 rate, 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.

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 photochromic properties 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 needs to be formed by a vacuum evaporation method or the like, and has a drawback that mass productivity is poor.

The present invention has been made in view of the above-mentioned problems in the prior art, and an object of the present invention is to provide a photochromic compound capable of forming an amorphous thin film with a photochromic compound alone without being dispersed in a polymer resin medium. It is to provide a compound and an excellent optical functional device using the same.

[0018]

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.

(Wherein R1 and R2 in each formula are hydrogen or an alkyl group, RA is an aromatic ring or a heterocyclic ring, and these may be the same or different, and may be unsubstituted. However, or some of them may be substituted.

As the substituent, an alkyl group, an aryl group,
Halogen, nitro, amino, alkoxy, and cyano groups.

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, C and D may be unsubstituted or partially substituted. As a substituent, an alkyl group,
An aryl group, a halogen group, a nitro group, an amino group, an alkoxy group, and a cyano group. n is an integer of 1 to 3. In addition, 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, and furthermore, a heterocyclic ring in the diarylethene skeleton is substituted by a sterically bulky substituent, a tetraarylmethyl group. It is a feature.

As described above, the photochromic compound of the present invention having a diarylethene skeleton exhibits a heat irreversible photochromic reaction, is thermally stable in both the colored state and the decolored state, and is excellent in repeated durability. It has the feature of.

Further, since the sterically bulky substituent is substituted in the molecule of the photochromic compound,
It is possible to form a stable glass 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 as in the case of a solution system. By using the photochromic compound of the present invention, a photochromic thin film having a large change in absorbance can be provided.

Further, the optical function element of the present invention is characterized in that an amorphous thin film made of a photochromic compound is formed on a substrate, and information is recorded on the thin film.

The amorphous thin film made of the photochromic compound of the present invention is not dispersed in a matrix such as a polymer, and is in a single state like the crystalline film described in the conventional example. Shows a larger absorbance change.

The amorphous thin film of the photochromic compound of the present invention can be formed by a coating method such as a spin coating method without using a large-scale apparatus such as a vacuum evaporation method required for forming a crystalline film.

It is another object of the present invention to provide an optical functional device characterized in that an amorphous thin film made of the photochromic compound is formed on a substrate and information is recorded on the thin film. Since the optical functional device of the present invention has the recording layer made of the photochromic compound exhibiting excellent optical characteristics, a high C / N ratio can be obtained.

[0031]

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 methods shown in FIGS.
However, the manufacturing method is not limited to this method, and can be manufactured by appropriately selecting from known methods.

That is, the heterocyclic compound shown on the left side of FIG. 3A is reacted with butyllithium. By adding zinc chloride to the reaction solution and reacting, a zinc compound shown on the right side of the reaction is synthesized.

Next, as shown in FIG. 3 (b), the zinc compound obtained in FIG. 3 (a) 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 in which the amino group is substituted as shown on the right side of FIG. 3B is synthesized.

When iodine and an aqueous solution of iodic acid are added to the amino-substituted heterocyclic compound obtained in FIG. 3 (b) and the reaction is carried out, iodine is substituted at the 3-position of the heterocyclic ring shown in the right of FIG. The synthesized compound is synthesized.

The iodine compound obtained in FIG. 3 (c) is reacted with butyllithium to generate anionic species by lithium-halogen exchange. The desired diarylethene (FIG. 3 (d) right) can be synthesized by reacting the ring A compound (substituted with a halogen atom) with this anionic species.

Here, in each formula, R1 and R2 are hydrogen or an alkyl group, RA is an aromatic ring or a heterocyclic ring, and may be unsubstituted or partially substituted. Substituents include alkyl, aryl, halogen, nitro, amino, alkoxy, cyano.

X represents an oxygen, sulfur or nitrogen atom. Particularly, a sulfur atom is preferable. Ring A is an aliphatic ring, an acid anhydride, or a maleimide group. Ring B, ring C and ring D may be unsubstituted or partially substituted. Substituents include alkyl, aryl, halogen, nitro, amino, alkoxy, cyano.

Since the photochromic compound of the present invention has a sterically bulky substituent, a tetraarylmethyl group, which is substituted in the molecule, the crystallization rate is suppressed, and as a result, a low molecular weight, stable glass is obtained. Indicates the status. Therefore, the photochromic compound can form an amorphous thin film by itself, and exhibits a reversible photochromic reaction similarly to a solution system. 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, and therefore has excellent optical characteristics such as a large change in absorbance and a change in refractive index.

Further, the photochromic thin film comprising the photochromic compound of the present invention can be applied by a coating method generally used for forming an organic thin film (a spin coating method, a bar coating method, an immersion method) 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.
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 a resin material such as polycarbonate having translucency, glass, or the like, as shown in a sectional view of FIG. A thin film made of a photochromic body produced by the method of the present invention is provided as a recording layer 2, and the reflective layer 3 is further provided.

The substrate 1 constituting the optical recording medium P1
Is a translucent plastic (for example, polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin,
Epoxy resin, polyimide resin), glass, ceramic, metal, or the like can be used. The recording layer has a thickness of 1
Laminated to a thickness of about 00 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 a vapor deposition method or the like. ), Etc., including the reflective layer 3 made of
(More preferably, about 100 ° to 3000 °).

If the thickness of the recording layer 2 is too small, the photosensitivity cannot be obtained, and if it is too large, the photoreaction speed decreases in the thickness direction. 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 substrate 1 is used as in the case of the optical recording medium P2 shown in FIG. 5, the reflective layer 3 is provided on the substrate 1, and then the recording layer 2 is provided thereon. Alternatively, light may be irradiated from the recording layer 2 side. In addition, these layer configurations are the minimum necessary 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, the optical recording medium P2 having a large change in reflectance and a good durability against repeated coloring and decoloring.
It can be.

In addition to the provision of the laminate comprising the recording layer and the reflective layer on the substrate as described above, a recording layer 2 is provided on a light-transmitting substrate 1 as shown in FIG. An optical recording medium P3 in which information is recorded by the incident light L1 and the information is reproduced based on a difference in light transmittance by detecting the incident light L1 and the emitted light L2 may be used. Also in this case, the recording layer may be covered with a light-transmitting protective layer or the like to form a multi-layer structure.

Further, as shown in FIG. 7, the present invention can be applied to an optical recording medium P4 utilizing a change in refractive index.
That is, when recording information, as shown in FIG. 8A, for example, an argon laser having a wavelength of 350 nm or a wavelength of 63 nm is used.
Irradiate the recording layer 2 through a beam splitter 21 and mirrors 22a and 22b using a writing light 23 of a 3 nm He-Ne laser,
Information is recorded on the recording layer 2 by changing the refractive index. Also,
To reproduce information, for example, as shown in FIG.
The information is reproduced by irradiating the recording layer 2 through the mirror 22a using the read light 24 of 830 nm and detecting the light by the detector 25.

In the embodiment of the present invention, a tetraaryl bulky substituent containing a diarylethene skeleton represented by the formula (1) in FIG. 1 or the formula (2) in FIG. A photochromic compound having an arylmethyl group and a case where an amorphous photochromic thin film made of the photochromic compound is applied to an optical recording medium have been described. However, the present invention is not limited to this. For example, an optical switch element, a dimming material, and an optical sensor And so on. 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.

[0049]

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. 12 was synthesized as follows.

(1) Synthesis of 2,4-dimethylthiophene (Formula (4) in FIG. 9) 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, and the mixture was added at 0 ° C for 1 hour.
And 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 a colorless liquid, 2,4-dimethylthiophene.

(2) Synthesis of 2,4-dimethyl-5- (4- (triphenylmethyl) phenyl) thiophene (Formula (5) in FIG. 10) 22.4 g of 2,4-dimethylthiophene in a 500 ml three-necked flask
(0.2mol), dry ethyl ether 200ml, TMEDA
(Tetramethylethylenediamine) 22.5g (0.22mol)
Was added, and while stirring at room temperature, 157 ml (1.4 M, 0.22 mol) of a normal butyllithium / hexane solution was added, and the mixture was stirred at room temperature for 2 hours.

After 2 hours, 200 ml of zinc chloride / ether solution (0.2 mol of zinc chloride) was added to the reaction system at room temperature, and the mixture was further stirred at room temperature for 5 hours (reaction solution A).

Next, 89.2 g (0.2 mol) of 4-iodo-tetraphenylmethane, 2.31 g of tetrakis (triphenylphosphine) palladium and 200 ml of dry tetrahydrofuran were put into another 500 ml three-necked flask, and stirred at room temperature for 1 hour. One hour later, the previously prepared reaction solution A was added to this reaction solution.
Was added dropwise at room temperature. After completion of the dropwise addition, the reaction system was heated to 50 ° C., and stirred at 50 ° C. for 2 hours and further at room temperature for 10 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 (5). (3) Synthesis of 3-iodo-2,4-dimethyl-5- (4- (triphenylmethyl) phenyl) thiophene (Formula (6) of FIG. 11) 2,4-dimethyl-5- ( 4- (triphenylmethyl) phenyl) thiophene (Formula (5)) 43.0 g (0.1
mol), acetic acid (650 ml) and carbon tetrachloride (650 ml). Add an aqueous solution of iodic acid (3.8 g (0.022 mol) of iodic acid / 10 m of water
l) and 8.73 g (0.034 mol) of iodine were added, and the mixture was heated under reflux for 2 hours. After heating to reflux, water was added to this to separate an organic layer and an aqueous layer, and the aqueous layer was extracted with chloroform. The organic layer was washed with an aqueous solution of sodium carbonate, sodium thiosulfate and 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).

(4) Synthesis of Photochromic Compound (Formula (3) in FIG. 12) 3-Iodo-2,4-dimethyl-5- (4-
(Triphenylmethyl) phenyl) thiophene (Formula (6)) 38.92 g (0.07 mol), dry tetrahydrofuran
The reaction system was cooled in a dry ice / methanol bath. To this reaction solution, 75 ml (0.105 mol) of a normal butyllithium / hexane solution was slowly added dropwise,
The mixture was stirred at -78 ° C for 1 hour. Then, 2.35 was added to the reaction solution.
ml (0.0175 mol) of perfluorocyclopentene,
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 compound of the formula (3)
The target compound as a white solid represented by was obtained.

Regarding the obtained four compounds (formulas (3) to (6)), 1H-NMR, 13C-NMR, FT-IR, GC / MS
As a result of structural analysis, all the compounds were confirmed to be the target products.

The absorption spectrum of the obtained photochromic compound (formula (3)) was measured.
m, it was found to have a maximum wavelength at 330 nm. Further, when this compound formula (3) was irradiated with ultraviolet light having a wavelength of 313 nm, the solution was colored, and the solution was observed near its absorption maximum of 610 nm.

Further, it was confirmed that the change in the absorption wavelength due to this light irradiation occurred reversibly. Then, it was confirmed that the crystal of the formula (3) obtained by the recrystallization melted at 265 ° 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, a glass transition phenomenon was observed at 110 ° C.

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 represented by the formula (3) had no defects due to crystallization even after being left for 3 months or longer, and that no deterioration in characteristics was observed. The obtained thin film 1
When XRD measurement and polarization microscopy were performed, only broad halos were observed in XRD measurement. It was confirmed that the film was a thin film.

Although the film is crystallized when left for a long time and a uniform film cannot be obtained, the thin film 1 represented by the formula (3) does not crystallize even after being left for 3 months or more and is a uniform amorphous film. That was confirmed.

For comparison, equation (3) is converted to PMMA.
A photochromic thin film (thin film 2) having a concentration of 30 parts by weight was prepared (thickness: 1 μm). In PMMA dispersion membrane,
It was confirmed that when the concentration of the formula (3) exceeded 30 parts by weight, characteristic deterioration occurred.

When the thin film 1 and the thin film 2 produced as described above were irradiated with ultraviolet light of 313 nm, the films were colored.
When the absorption spectrum of the film at this time was measured, FIG.
As shown in FIG. 3, it was confirmed that each of the thin films had an absorption maximum near 310 nm. Furthermore, it was confirmed that the change of the absorption wavelength due to this light irradiation occurred reversibly. It was found that a reversible photochromic reaction proceeds even in a thin film state.

Further, after irradiating the thin film 1 and the thin film 2 in the colorless state with light of 313 nm of ultraviolet light until the light steady state, 610 nm
When the absorbance change at was measured, the thin film 1 was
It was confirmed that the absorbance change was about three times larger. This is considered to be because the function of the photochromic molecules was effectively exhibited by forming the thin film 1 as an amorphous thin film using the photochromic compound alone as compared with the PMMA dispersion system.

Example 3 Using the photochromic thin film obtained in Example 2, an optical recording medium P1 shown in FIG. 4 was produced. 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.

By irradiating the entire surface of the optical recording medium with ultraviolet light,
After bringing the photochromic compound of the recording layer into a colored state,
Recording and reproduction were evaluated using a device equipped with a 680 nm semiconductor laser in a pickup. When recording was performed with a power of 10 mW and reproduction was performed with a power of 0.2 mW, a reproduced signal having a high C / N ratio of 50 db or more was obtained. Further, the number of times of reproduction was 10,000 times or more.

[Example 4] Further, the thin film 1 and the thin film 2 in the colorless state were examined for changes in the refractive index before and after light irradiation with an ultraviolet He-Ne laser. As shown in FIG. It was found that the film thickness of the thin film 1 was 5 × 10 ⁻² , whereas it was 10 ⁻³ . This is considered to be because the thin film 1 was formed as an amorphous thin film using only the photochromic compound, and the refractive index change due to the change in the photochromic molecular structure had a greater effect than the PMMA dispersion system.

Example 5 Using the photochromic thin film obtained in [Example 2], an optical recording medium shown in FIG. 7 was prepared, and data was recorded on the photochromic thin film using an argon laser (363 nm) as recording light. . The recorded data could be read out as a difference in refractive index with a semiconductor laser (830 nm).

[0069]

The photochromic compound of the present invention contains a diarylethene skeleton and has a sterically bulky substituent in the molecule, so that an amorphous thin film can be formed with the photochromic compound alone. . As a result, the function of the photochromic molecule can be effectively exhibited, so that a photochromic thin film having excellent optical characteristics can be provided.

Further, in forming a thin film, a large-scale apparatus such as a vacuum evaporation method is not required, and the thin film can be formed by a 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.

Further, since the change in absorbance and the change in refractive index before and after light irradiation are much larger than those of the 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 sectional view illustrating an optical recording medium P1 of the present invention.

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

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

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

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

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

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

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

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

FIG. 13 is a diagram showing a change in absorbance of the photochromic thin films 1 and 2 before and after light irradiation.

FIG. 14 is a diagram showing a change in the refractive index of the photochromic thin films 1 and 2.

[Explanation of symbols]

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

Claims (2)

[Claims] 1. A photochromic compound represented by the following formula (1) or (2). Embedded image Embedded image (However, R1 and R2 in each formula are hydrogen or an alkyl group, RA is an aromatic ring or a heterocyclic ring, and includes those having a substituent in part. X is an oxygen atom, a sulfur atom or a nitrogen atom. Atom A. Ring A is an aliphatic ring, an acid anhydride, or a maleimide group, and ring B, ring C, and ring D include those each partially having a substituent, and n is an integer of 1 to 3.) 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.