JP2001048875A - Photochromic compound and optical function element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound which is a compound containing a triarylamino group on a hetero ring in a diarylethene skeleton, is capable of singly forming an amorphous thin film, has a great change in optical characteristics before and after light irradiation, useful in the field of optical information. SOLUTION: This compound is shown by formula I [R1 to R6 are each a (substitute) aryl; R7 and R8 are each H, an alkyl or the like; X is O, S or the like; ring A is an aliphatic group, an aromatic group or the like; and rings B and C each may contain a substituent] such as a compound of formula II. The compound of formula I is obtained by successively reacting a heterocyclic compound with butyllithium, zinc chloride, an iodated amine compound, iodine, an aqueous solution of iodic acid and butyllithium and finally reacting the resultant substance with a ring A compound. The compound of formula I readily forms a thin film. For example, an optical recording medium P1 can be constituted by forming the thin film of the compound as a recording layer 2 on a substrate 1 composed of glass, etc., and providing a reflecting layer 3 on the thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel photochromic compound and an optical functional device using the same, and more particularly to a photochromic compound suitable for an optical information processing field.

[0002]

2. Description of the Related Art A photochromic material contains a molecule or a molecular assembly that reversibly generates two isomers having different states upon irradiation with light, and the molecular structure is changed by a photochemical reaction. It has the property of reversibly changing optical characteristics such as light absorption coefficient, refractive index, optical rotation, or dielectric constant according to. By utilizing the difference between these optical characteristics, information can be recorded / reproduced, and information can be erased by restoring the molecular structure.

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

A (λ1) → A (λ2) (F1) A (λ1) ← A (λ2) (F2) Here, A (λ1) and A (λ2) are absorption spectra, respectively. The above formula (F1) is an isomerization reaction caused by irradiation with light having a wavelength of λ1, and the formula (F2) is an isomerization reaction caused by irradiation with light having a wavelength of λ2.

When a photochromic material 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 absorbing light, and the data can be erased by irradiating light of the other wavelength.

Normally, data is read out based on the difference in absorbance between the isomers (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.

When a photochromic material is applied to an optical functional element such as an optical recording medium, it is necessary to form a thin film containing the photochromic material. Heretofore, a method of dispersing a photochromic material 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 conversion becomes maximum at a concentration of about 30 parts by weight with respect to 100 parts by weight of the polymer. Furthermore, some photochromic materials have poor compatibility with polymers and poor dispersibility. As a result, sufficient characteristics have not been obtained so far.

In view of such circumstances, a diarylethene compound having a photochromic property in a crystalline state has been proposed. The diarylethene compound having a photochromic property in a crystalline state can be formed by vapor deposition without dispersing in a polymer resin. Can form a photochromic thin film having higher absorbance (M.Irie, Chem. Lett. 899 (1.
995) and JP-A-8-1199633).

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 it is inferior in mass productivity as compared with the conventional one.

As described above, data is normally read out due to the difference in absorption. However, since the photochromic reaction itself does not have a threshold value, in this method, data is destroyed during reproduction, and data is read out many times. Can not do. For this reason, non-destructively reading out data is one of the problems of the photochromic optical memory.

To achieve non-destructive reading, the following two methods are conceivable. A photochromic material having a threshold for photoreaction and a material in which three isomers react are obtained.
A method of reading data without absorption is adopted. 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).

Since the photochromic material has a photorefractive effect in which the refractive index changes reversibly by light irradiation, it can be applied to an optical memory utilizing this effect. That is, the bit data recorded on the medium by the 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 for several 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 (Sr _x Ba _{1 -x} Nb ₂
O ₆ ) and lithium niobate (LiNbO ₃ ). This is because the refractive index changes greatly when an electric field is applied, and the changed refractive index is stably held,
When light irradiation is performed in yet another pattern, a so-called reversible change in the refractive index occurs such that the first pattern is erased and a new pattern is formed.

In recent years, similar effects have been reported for organic substances. The characteristic of organic substances is that the change in the refractive index is several times to several tens times larger than that of inorganic substances.
It has been proposed to use a photochromic material as the photorefractive organic material. Photochromic materials change their refractive index just by irradiating light,
Without consuming energy even after the refractive index changes,
This has the advantage that the refractive index can be maintained in a changed state. 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.

While the above-mentioned photorefractive inorganic substance has been used as a single crystal, it has been very difficult to produce a high-quality single crystal in the case of an organic substance so far, so that a high-quality single crystal such as polymethyl methacrylate or polystyrene is used. A method of dispersing in a molecular matrix has been generally used. In this case, in order to cause a large change in the refractive index, it is necessary to increase the concentration of the organic material dispersed in the transparent medium. However, if the organic material is dispersed at a certain concentration or more, phase separation occurs with the dispersion medium and the medium becomes opaque. Further, the organic material itself has a disadvantage in that it can associate in the polymer matrix, and the characteristics are deteriorated. Therefore, in a dispersion film in which organic molecules are dispersed in a transparent medium, a sufficient change in refractive index cannot be obtained,
Satisfactory device characteristics could not be obtained.

In view of such circumstances, diarylethene compounds having photochromic properties in an amorphous state have been devised (Jpn. J. Appl. Phys. 38 (1999) L119).
4, see JP-A-9-241254). Amorphous diarylethene can be formed into a thin film by a coating method such as a spin coating method, and has an advantage of being excellent in mass productivity. However, the amorphous diarylethene obtained so far has a glass transition temperature of 7
As low as about 0 ° C., there was a problem in thermal stability.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to form an amorphous thin film using a photochromic compound alone without dispersing it in a polymer resin medium. An object is to provide an excellent photochromic compound having a large change in optical properties such as absorbance and refractive index before and after light irradiation and a glass transition temperature of 100 ° C. or higher, and an optical functional device using the same.

[0021]

The photochromic compound of the present invention for solving the above problems is represented by the formula (1) or (2) as shown in FIGS. The photochromic compound of the present invention includes a compound (optical isomer) obtained by irradiating the formula (1) or (2) with light.

Here, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each represent an aryl group, and a part thereof may be substituted. A group, an aryl group, a halogen group, a nitro group, an amino group, an alkoxy group, or a cyano group. R ⁷ and R ⁸ are each hydrogen or an alkyl group or an alkoxy group capable of imparting the same properties (thermal stability and repetition durability). X is an oxygen atom, a sulfur atom, or a nitrogen atom. Ring A is an aliphatic ring, an aromatic ring, an acid anhydride, or a maleimide group. Further, the ring B and the ring C may be partially substituted, and examples of the substituent include an alkyl group, an aryl group, a halogen group, a nitro group, an amino group, an alkoxy group, and a cyano group. . Note that N is nitrogen.

Further, a photochromic compound represented by the formula (3) or (4) as shown in FIGS.
However, ring A is composed of an aliphatic ring, and its substituent (C
Z ₂ ) Z of n is a halogen atom, and n is an integer of 2 to 5. Note that ring B, ring C and N are the same as above,
C in Z ₂ is carbon.

Further, a photochromic compound represented by the formula (5) or (6) as shown in FIGS.
However, ring A is composed of a maleimide derivative. R ⁹ is hydrogen, an alkyl group, an aryl group, an alkoxy group, an amino group, a halogen atom, a nitro group, or a cyano group, of which an alkyl group, an aryl group, an alkoxy group, and an amino group are partially substituted. May be allowed. Note that Ring B, Ring C and N are the same as above, and O is oxygen.

Further, a photochromic compound represented by the formula (7) or (8) as shown in FIGS.
However, ring A is composed of a maleic anhydride derivative. In addition, ring B, ring C, N, and O are the same as above.

The photochromic compound can be made amorphous at room temperature, and the amorphous thin film made of the photochromic compound does not need to be dispersed in a matrix such as a polymer resin or the like. , A larger change in optical characteristics is exhibited as compared with the dispersion film. In addition, since the glass transition temperature is 100 ° C. or higher, the glass transition temperature is excellent.

The amorphous thin film can be formed by a simple 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.

Further, the optical functional device of the present invention is such that an amorphous thin film made of the photochromic compound is formed on a substrate, and information is recorded on the thin film. According to this optical function element, a high C / N ratio can be obtained because it has the recording layer (thin film) made of the photochromic compound.

The photochromic compound specifically has a diarylethene skeleton, and further has a chemical structural feature that a triarylamino group is substituted on a heterocycle in the diarylethene skeleton.

As described above, the photochromic compound having the diarylethene skeleton exhibits a thermo-irreversible photochromic reaction as shown in FIGS. 9 and 10, and both the colored state and the decolored state are thermally affected. It is stable and has excellent repetition durability. Here, the reaction to the right compound (ring closed body) in FIGS. 9 and 10 proceeds by irradiation with ultraviolet light of 350 nm or less,
The reaction to the left compound (partially ring-opened) was 450 n
m or more by irradiation with visible light.

Further, since a triaryl group 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 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. By using the photochromic compound, a photochromic thin film having a large change in absorbance can be provided.

The amorphous thin film made of the photochromic compound of the present invention is not dispersed in a matrix such as a polymer, but is in a single state like the crystalline film described in the conventional example. It shows a larger change in the refractive index as compared with. By utilizing this large change in the refractive index, it can be suitably used as an optical transmission line for an optical switch.

[0033]

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

The photochromic compound represented by the formula (1) or (2) shown in FIGS.
It can be synthesized by the methods shown in (a) to (d).

That is, first, as shown in FIG. 14A, a heterocyclic compound is reacted with butyllithium. A zinc compound is synthesized by adding zinc chloride to the reaction solution to cause a reaction.

Next, as shown in FIG. 14 (b), the zinc compound obtained in FIG. 14 (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 substituted with an amino group is synthesized.

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

Then, the iodine compound obtained in FIG. 14 (c) is reacted with butyllithium to generate anionic species by lithium-halogen exchange. By reacting the anion species with a ring A compound (substituted by a halogen atom), the desired diarylethene can be synthesized.

The above synthesis method relates to the compound of the formula (1), but the formula (2) can also be synthesized by the same method. Here, X represents an oxygen atom, a sulfur atom, or a nitrogen atom. Particularly, a sulfur atom is preferable since the right compound (ring-closed body) in FIGS. 9 and 10 has the highest thermal stability.

In addition, the substituent (C) shown in FIGS.
Z in Z ₂ ) n represents a halogen atom, and is particularly preferably a fluorine atom, because the reactivity in FIG. 14D is excellent and the yield is increased.

Since the above photochromic compound has a triaryl group substituted in the molecule, it exhibits a stable glass state even though it has a low molecular weight. Therefore, the photochromic compound can form an amorphous thin film by itself, and exhibits a reversible photochromic reaction similarly to the solution system. Unlike the polymer resin dispersed film, the photochromic thin film composed of the above photochromic compound is an amorphous thin film composed of a single photochromic compound, so that the optical properties such as the light absorption coefficient, the refractive index, the optical rotation, and the dielectric constant are also transparent. It shows a large value as compared with a dispersion film dispersed in a medium.

When the photochromic thin film is irradiated with ultraviolet light, a photochromic reaction proceeds in the film and the film is colored. The optical properties of the photochromic thin film before and after light irradiation change significantly as compared with the dispersion film. In particular, the refractive index change is remarkable, and the conventional dispersion film has a refractive index change of the order of 10 ⁻⁴ , while the photochromic thin film composed of amorphous photochromic molecules exhibits a refractive index change of the order of 10 ⁻² or more. Furthermore, if this is used for an optical transmission line for an optical switch, the switching is completed within several nanoseconds, so that an excellent optical switching element capable of high-speed response can be provided. In addition, the photochromic thin film can be applied by a coating method (spin coating method, bar coating method, immersion method, melt extrusion method, or spray method) generally used for forming an organic thin film without using a large-scale apparatus such as vacuum evaporation. Etc.). Specifically, a thin film can be formed by dissolving the photochromic compound in a highly viscous organic solvent, applying the solution, and performing heat treatment at about 80 to 150 ° C.

Further, 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. 11, an optical recording medium P1 was produced by a method of the present invention on a disk-shaped substrate 1 made of, for example, a resin material such as polycarbonate having translucency or glass. It is possible to provide a thin film made of a photochromic body as the recording layer 2 and further provide the reflective layer 3 thereon.

The substrate 1 constituting the optical recording medium P1 is
Light-transmitting plastic (eg, polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, or polyimide resin), glass, ceramic, metal, or the like can be used. The recording layer 2 has a thickness of 100
A metal layer (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. of the reflective layer 3
Lamination is performed at about 000 ° (more preferably, 100 ° to 3000 °).

If the thickness of the recording layer 2 is too thin, the photosensitivity cannot be obtained. On the other hand, if the thickness is too large, the photoreaction speed decreases in the thickness direction, which is not preferable. If the thickness of the reflective layer 3 is too small, 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, for example, as shown in FIG. 12, a recording layer 2 is provided on a substrate 1 'having a reflection function, and information is recorded by incident light L1. Alternatively, an optical recording medium P1 'configured to reproduce information using the reflected light L2 may be used. In addition, in FIG. 11, the reflective layer 3 may be provided on the substrate 1, then the recording layer 2 may be provided thereon, and 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, it is possible to obtain an optical recording medium P1 having a large change in reflectivity and a good durability against repeated coloring and decoloring.

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. Incident light L3
The optical recording medium P2 may be configured such that information is recorded on the optical recording medium and the information is reproduced based on a difference in light transmittance by detecting the incident light L3 and the output light L4. In this case, also in this case, the recording layer may be covered with a translucent protective layer or the like to form a multi-layer structure.

When the reproduction of the optical recording medium is performed by the difference in the refractive index of the recording layer, the basic configuration of the layer is the same as that of the optical recording medium P2 shown in FIG. 13, and this is arranged in an optical system as shown in FIG. However, it is also possible to record and reproduce information.
That is, when information is recorded, as shown in FIG. 21A, for example, a writing light 23 such as an argon laser having a wavelength of about 350 nm or a He-Ne laser having a wavelength of about 633 nm is used, and the beam splitter 21, the mirror 22a, and the like are used. Irradiation is performed on the recording layer 2 through 22b to change the refractive index of the recording layer 2 and record information. For reproducing information, for example, as shown in FIG.
The information is reproduced by irradiating the recording layer 2 through the mirror 22a using the reading light 24 of about m and detecting it with the detector 25.

Further, the photochromic thin film of the present invention
For example, it can be suitably used for the optical transmission line of the optical switching element shown in FIG. Conventionally, in the case of optical switching using a photorefractive material, there was a problem that an electric field had to be applied, but when using the photochromic thin film of the present invention, it was possible to control only by light without applying an electric field. Therefore, it is possible to operate without consuming energy.

For example, a 2 × 2 Mach-Zehnder type optical waveguide device H using the above photochromic material is shown in FIG.
Shown in In the figure, 11 is a substrate for an optical waveguide made of a transparent material such as glass, 12 is a cladding layer made of PMMA (polymethyl methacrylate) or the like, 13 is an upper cladding layer made of a photochromic thin film, and 14 is a fluorine-doped PMMA. An optical waveguide in which a photochromic material such as a diarylethene derivative is partially dispersed, 15
Is an optical waveguide made of PMMA doped with fluorine, and 16 is an optical functional part of the optical waveguide 14 made of the photochromic material.

In such an optical waveguide device H, when ultraviolet light (wavelength of about 380 nm or less) or blue light (wavelength of about 380 to about 450 nm) is irradiated from the back surface of the substrate 11, the molecular structure and the refractive index of the optical function part 16 are increased. Is changed, and infrared light (signal light: wavelength 1.55 μ) incident from ports 1 and 2
m)) is such that the optical waveguides 14 and 15 are coupled at the branching part B1 where the optical waveguides 14 and 15 approach and separate from each other and act as interference, etc.
And combine again. Then, when multiplexing is performed at the branch portion B2, interference occurs according to the phase difference of the light individually guided through the optical waveguides 14 and 15, and the intensity of the emitted light from the ports 3 and 4 can be controlled.

Further, red light (wavelength 6
About 00 to 780 nm) or yellow light (wavelength 450 to 60).
By irradiating (about 0 nm), the molecular structure of the optical function part 16 returns to the original state, and becomes the refractive index before irradiation with ultraviolet light or blue light.

At this time, if the refractive index is changed as described above, the wavelength of light propagating through the optical function part 16 changes. The lights branched in the same phase at the branching section B1 are combined at the branching section B2, but the optical output ratio of the ports 3 and 4 can be adjusted by controlling the phase difference between the two lights reaching the branching section B2. . The extent to which the phase difference can be controlled is proportional to the length of the optical function unit 16, and a desired switching function can be obtained by optimally setting the length of the optical function unit 16.

In the embodiment of the present invention, a photochromic compound having a diarylethene skeleton represented by the formulas (1) and (2) shown in FIGS. 1 and 2 and further having a triarylamino group in the molecule is provided. The case where the amorphous photochromic thin film made of a compound is applied to an optical waveguide used for an optical recording medium, an optical switch element, and the like has been described. However, the present invention is not limited to this, and is applicable to, for example, a dimming material or an optical sensor. It is possible. 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.

[0057]

The present invention will be described below in more detail with reference to examples. It should be noted that the present invention is not limited to these embodiments unless departing from the gist of the present invention. Example 1 A photochromic compound of the formula (9) shown in FIG. 15 was synthesized as follows. (1) 2,4-dimethylthiophene (Formula (10) in FIG. 16)
Synthesis: First, into a 300 ml three-necked flask
25.5 g (0.26 mol) of 3-methylthiophene, 125 ml of dry ether, and 33.2 g of TMEDA (tetramethylethylenediamine) were added, and the reaction system was cooled to 0 ° C. To this reaction solution, a mixed solution obtained by dissolving 204 ml of normal butyllithium in hexane was slowly dropped, and the mixture was stirred at 0 ° C. for 1 hour and further at room temperature for 2 hours.

Next, 17.5 ml of methyl iodide was added while cooling again on 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. Here, the yield in this case was 19.8 g, and the yield was 68%. (2) Synthesis of 2,4-dimethyl-5- (4- (N, N′-diphenylamino) phenyl) thiophene (Formula (11) shown in FIG. 17): 2,4-dimethyl was added to a 500 ml three-necked flask. 22.4 g (0.2 mol) of thiophene, 200 ml of dry ethyl ether, 22.5 g of TMEDA
(0.22 mol), while stirring at room temperature, 177 ml of a normal butyl lithium / hexane solution (1.4 mol (mol / l), 0.22 mol)
Was added and stirred at room temperature for 2 hours.

Two hours later, 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, 92.3 g (0.2 mol) of 4-iodo-4 ′, 4 ″ -dimethyltriphenylamine and 2.30 g of tetrakis (triphenylphosphine) palladium were placed in another 500 ml three-necked flask. 31 g and 200 ml of dry tetrahydrofuran were added and stirred at room temperature for 1 hour. One hour later, the previously prepared reaction solution A was added dropwise to the reaction solution at room temperature. After completion of the dropwise addition, the reaction system
Heat to 0 ° C., 50 ° C. for 2 hours, and room temperature for 5 hours
Stirring was performed for 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 (11). Here, the yield in this case was 70.74 g, and the yield was 92%. (3) 3-Iodo-2,4-dimethyl-5- (4- (N, N'-diphenylamino) phenyl) thiophene (Formula (12) in FIG. 18)
Synthesis of 2,4-dimethyl-5 in a 2 liter three-necked flask
38.3 g (0.1 mol) of-(4- (N, N′-diphenylamino) phenyl) thiophene (formula (11) in FIG. 17),
650 ml of acetic acid and 650 ml of carbon tetrachloride were charged. An aqueous iodic acid solution (3.8 iodic acid)
g (0.022 mol) in 10 ml of water and 8.73 g (0.034 mol) of iodine were added, and the mixture was heated under reflux for 2 hours. After the completion of the heating and refluxing, water was added thereto to separate an organic layer and an aqueous layer, and the aqueous layer was extracted with chloroform.

Then, the organic layer was treated with an aqueous solution of sodium carbonate,
After washing with sodium thiosulfate and further with water, it was 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.
A colorless liquid target compound represented by the formula (12) was obtained. Here, the yield in this case was 36.65 g, and the yield was 72%. (4) Synthesis of photochromic compound (formula (9)): 50
35.63 g (0.07 mol) of 3-iodo-2,4-dimethyl-5- (4- (N, N'-diphenylamino) phenyl) thiophene (formula (12) in a 0 ml three-necked flask was dried. 150 ml of tetrahydrofuran was added, the reaction system was cooled in a dry ice / methanol bath, and 75 ml (0.105 mol) of a normal butyl lithium / hexane solution was slowly added dropwise to the reaction solution.
The mixture was stirred at -78 ° C for 1 hour.

Next, 2.35 ml (0.0175 mol) of perfluorocyclopentene was added to the reaction solution, and the mixture was stirred at 0 ° C. for 5 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 (9) in FIG. . Here, the yield in this case was 38.08 g, and the yield was 58%.

The obtained four compounds (formulas (9) to (1)
Regarding 2)), ¹ H-NMR, ¹³ C-NMR, FT-
Structural analysis was performed by IR and GC / MS, and it was confirmed that all the compounds were the target products. Example 2 The photochromic reaction of the photochromic compound (formula (9)) obtained in Example 1 was examined.
As shown in FIG. 27, the compound of formula (9)
And a maximum wavelength at 333 nm. The molar extinction coefficient is 48000 (306 nm), 52,000
(333 nm). Further, when this compound was irradiated with ultraviolet light having a wavelength of 313 nm, the solution was colored blue and its absorption maximum was 595 nm.
Observed nearby. The molar extinction coefficient of the compound of the formula (9a) was 21000 (595 nm).

The photochromic reaction proceeded reversibly by irradiation with ultraviolet light and visible light. The quantum yields of the ring closure reaction (left to right) and the ring opening reaction (right to left) in FIG. 23 were 0.44 and 0.005, respectively. It was also found that the isomerization ratio to the compound of the formula (9a) in the photo-steady state was almost 100%.

As a result of the DSC measurement, equations (9) and (9)
It was confirmed that the compound of a) had glass transition temperatures around 103 ° C. and 124 ° C., respectively. It showed the highest value as a material showing reversible photochromism by light.
In addition, it has been found that the formula (9a) has an exothermic peak derived from an isomerization reaction due to heat (heat return) near 180 ° C.
Formula (9a) is sufficiently stable at room temperature, but it was confirmed that the photoisomerization reaction proceeds with heat of about 200 ° C. Example 3 A photochromic thin film (thin film) was prepared by dissolving the photochromic compound (formula (9)) obtained in Example 1 in toluene, applying the solution on a quartz substrate by spin coating, and baking at 90 ° C. 1) was produced (film thickness 1 μm). In general, an organic thin film has a strong tendency to crystallize, and crystallizes when left for a long time, and the crystallized portion becomes a defect to cause deterioration in characteristics. However,
It was confirmed that the thin film 1 composed of the compound of the formula (9) did not generate defects due to crystallization even after being left for more than half a year, and no further deterioration in characteristics was observed. When the obtained thin film 1 was subjected to X-ray diffraction measurement and observation with a polarizing microscope, only a broad halo was observed in the X-ray diffraction measurement. And it was confirmed that the film was a uniform amorphous thin film.

When the thin film 1 produced as described above was irradiated with ultraviolet light (313 nm), the film was colored green. When the absorption spectrum of the thin film at this time was measured, FIG.
As shown in FIG. 8, it was confirmed to have an absorption maximum near 606 nm. Furthermore, it was confirmed that the change in the absorption wavelength due to this light irradiation occurred reversibly. Then, it was found that a reversible photochromic reaction proceeds even in a thin film state.

Since the thin film 1 is a single film composed of the compound of the formula (9), a sufficient change in absorbance was obtained without securing a sufficient film thickness. In the conventional polymer dispersed film, in order to obtain a sufficient change in absorbance, it is necessary to improve the dispersion concentration and the film thickness, which is not efficient.

Further, it has been found that the photoisomerization reaction of the thin film 1 proceeds even with He-Cd laser light (wavelength: 442 nm), unlike the polymer dispersed film. In addition, since it is a single amorphous film, unlike the state of the dispersion film, it is considered that the π-electron conjugate length is extended.

Thus, since the semiconductor thin film can be used for the amorphous thin film made of the material of the present invention, the versatility of the system can be improved and the size can be reduced.

Further, even when the obtained thin film 1 was repeatedly subjected to the photochromic reaction 10,000 times or more, no deterioration in the characteristics due to the deterioration of the compound was observed. In a dark place at 80 ° C, 5
No characteristic deterioration was observed even after leaving for more than 00 hours.

Comparative Example 1 For comparison, a compound of the formula (13) shown in FIG. 24 in which an ethyl group was introduced in place of the substituent on the nitrogen (tolyl group) in the compound of the formula (9) was used.
When a thin film was prepared by spin coating, crystallization proceeded quickly after the film was formed, and a uniform amorphous thin film could not be obtained.

Comparative Example 2: As a further comparison, a photochromic thin film (thin film 2) having a concentration of 30 parts by weight of the compound of the formula (9) dispersed in PMMA was prepared to a thickness of 1 μm. P
In the case of the MMA-dispersed film, it was confirmed that when the concentration of the formula (9) exceeded 30 parts by weight, characteristic deterioration occurred (see FIG. 20). Example 4 The thin films 1 and 2 prepared in Example 3 and Comparative Example 2 were 633 nm, 817 nm, and 1
Irradiation with a laser beam of 550 nm was performed, and changes in the refractive index before and after irradiation with ultraviolet light were examined.

As shown in FIGS. 25 and 26, it was confirmed that the refractive index was increased as the photochromic reaction by irradiation with ultraviolet light progressed. As described above, by controlling the light irradiation amount, the refractive index can be controlled in an analog manner, so that it can be suitably applied to a hologram memory, multilayer recording, and the like.

The difference in the refractive index between the state before light irradiation and the light steady state was 2 × 10 ⁻³ for the thin film 2 (see FIG. 26), whereas 1.2 × for the thin film 1 was larger by one digit. 10 ^-2
(See FIG. 25). This is a thin film
1 is an amorphous thin film formed of a photochromic compound alone,
This is considered to be because the change in the refractive index due to the change in the photochromic molecular structure had a large effect. Example 5 An optical recording medium P1 shown in FIG. 11 was manufactured using the photochromic thin film obtained in Example 3. A recording layer composed of the photochromic compound (formula (9)) obtained in Example 1 was laminated on a translucent polycarbonate substrate, and a reflective layer composed of an Al layer was laminated thereon. Then, a protective layer made of an acrylic resin was formed thereon to produce 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 having semiconductor lasers having wavelengths of 400 nm and 680 nm mounted on a pickup. When recording was performed with a 400 nm laser at a power of 10 mW and reproduction was performed with a 680 nm laser at a power of 0.2 mW, a reproduced signal having a high C / N ratio of 50 dB or more was obtained. The number of times of reproduction was 10,000 times or more. Embodiment 6 Using the photochromic thin film obtained in Embodiment 3, an optical recording medium P2 shown in FIG.
Using a -Cd laser (wavelength 442 nm) as recording light, data was recorded on the photochromic thin film. The recorded data could be read out (reproduced) as a difference in refractive index with a semiconductor laser (wavelength 830 nm). Example 7 An optical waveguide was manufactured using the photochromic thin film 1 obtained in Example 3, and a switching phenomenon was confirmed. That is, an optical waveguide device as shown in FIG. 22 was manufactured. Here, 11 is a glass substrate, 12 is a clad layer made of PMMA, 13 is an upper clad layer made of the photochromic thin film 1, 14 is an optical waveguide made of fluorine-doped PMMA, and a photochromic material of a diarylethene derivative is partially dispersed therein. , 15 is PM with fluorine
The optical waveguide 16 made of MA is an optical functional portion of the optical waveguide 14 made of the photochromic material. Light having a wavelength of 1.55 μm was passed through the produced waveguide, and when irradiated with ultraviolet light, the refractive index was changed, and the wavelength was 1.55 μm.
It has been found that m light can be switched. It was also found that the switching speed was at least 10 ⁴ times faster than that of a waveguide made of a conventional dispersion film.

[0077]

[Effects of photogenicity] Since the photochromic compound of the present invention contains a diarylethene skeleton and further has a triarylamino group in the molecule, it is possible to form an amorphous thin film with the photochromic compound alone. Can effectively exert the function of the photochromic thin film having excellent optical characteristics.

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 greatly improved as compared with the conventional one. it can.

Further, when the photochromic thin film of the present invention is used for a recording layer of an optical functional device, it is possible to provide a film having excellent repetition durability and excellent optical characteristics, and a change in absorbance before and after light irradiation. And the refractive index change is much larger than the conventional polymer resin dispersion film,
An excellent optical recording medium and an optical transmission line for an optical switch can be provided.

[Brief description of the drawings]

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

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

FIG. 3 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 4 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 5 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 6 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 7 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 8 is a view showing a chemical formula of a photochromic compound according to the present invention.

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

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

FIG. 11 is a schematic sectional view illustrating an optical recording medium according to the present invention.

FIG. 12 is a schematic sectional view illustrating an optical recording medium according to the present invention.

FIG. 13 is a schematic sectional view illustrating an optical recording medium according to the present invention.

14 (a) to (d) are chemical reaction formulas for synthesizing a photochromic compound according to the present invention.

FIG. 15 is a view showing a chemical formula of a photochromic compound according to the present invention.

FIG. 16 is a view showing a chemical reaction formula when synthesizing a photochromic compound according to the present invention.

FIG. 17 is a view showing a chemical reaction formula when synthesizing a photochromic compound according to the present invention.

FIG. 18 is a view showing a chemical reaction formula when synthesizing a photochromic compound according to the present invention.

FIG. 19 is a view showing a chemical reaction formula when synthesizing a photochromic compound according to the present invention.

FIG. 20 is a diagram showing dispersion concentration dependency in a PMMA dispersion film.

FIGS. 21A and 21B are schematic cross-sectional views illustrating a method for recording and reproducing information on an optical recording medium according to the present invention, respectively.

FIG. 22 is a perspective view schematically illustrating an optical waveguide according to the present invention.

FIG. 23 is a diagram illustrating a photochromic reaction according to the present invention.

FIG. 24 is a view showing a chemical formula of a photochromic compound for explaining a comparative example with respect to the example of the present invention.

FIG. 25 is a diagram illustrating a change in the refractive index of the thin film 1;

FIG. 26 is a diagram illustrating a change in the refractive index of the thin film 2;

FIG. 27 is a diagram showing a change in absorbance of the photochromic compound according to the present invention before and after irradiation with ultraviolet light.

FIG. 28 is a diagram showing a change in absorbance of a thin film 1 before and after irradiation with ultraviolet light.

[Explanation of symbols]

 1: substrate 2: recording layer 3: reflective layer P1, P1 ', P2: optical recording medium H: optical waveguide element

Claims (3)

[Claims] 1. A photochromic compound represented by the following formula (1) or (2). Embedded image Embedded image (However, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each an aryl group or a partially substituted aryl group, and R ⁷ , R ⁸
Is hydrogen, an alkyl group or an alkoxy group, respectively. X
Represents an oxygen atom, a sulfur atom or a nitrogen atom. The ring A is composed of an aliphatic ring, an aromatic ring, an acid anhydride or a maleimide group, and each of the rings B and C may have a substituent. ) 2. An optical functional device wherein information is recorded by irradiating a thin film made of the photochromic compound according to claim 1 with light. 3. An optical functional device, wherein the thin film made of the photochromic compound according to claim 1 is used for an optical transmission line for an optical switch.