JP2002293784A - Photochromic compound and optical function element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photochromic compound comprising an amorphous diarylethene compound having >=100 deg.C glass transition temperature, and further to provide an optical function element by using the compound. SOLUTION: This compound having a refractive index reversibly changeable by light is represented by formula (1) (wherein, R<1> and R<2> are each hydrogen, an alkyl group or an alkoxy group; R<3> , R<4> , R<5> and R<6> are each hydrogen, an alkyl group, an alkoxy group or an aryl group which may be unsubstituted or a part of which may be substituted with a substituent exemplified by an alkyl group, an aryl group, a halogen group, a nitro group, an amino group, an alkoxy group or a cyano group; RA is an aromatic ring or a heterocycle a part of which may have a substituent; and X is an oxygen, sulfur or nitrogen atom) and includes a ring A comprising an aliphatic ring, an acid anhydride or a maleimide group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Since a photochromic compound has a property of reversibly changing optical characteristics, information can be recorded / reproduced by utilizing a difference between these optical characteristics. In addition, since the photochromic compound has a photorefractive effect in which the refractive index is reversibly changed by light irradiation, application to an optical memory element and an optical switching element is expected.

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.

[0004] Such a property is very effective not only for optical memories but also for optical switching elements. 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 method of forming a thin film, a method of dispersing a photochromic compound in a polymer matrix such as polymethyl methacrylate or polystyrene has been generally used.

However, as the concentration of the photochromic compound increases, the conversion ratio decreases because the photochromic compound itself associates with the photochromic compound.
It is known that the maximum value is obtained at a concentration of about 0 parts by weight. Further, some photochromic compounds have poor compatibility with polymers and poor dispersibility. As a result, sufficient characteristics have not been obtained so far.

Therefore, a diarylethene compound having a photochromic property in a crystalline state has the advantage that a photochromic thin film having a high absorbance can be formed by vapor deposition or the like without dispersing it in a polymer resin as well. It is described in the gazette.

Japanese Patent Application Laid-Open No. 2000-256664 describes that a diarylethene compound having photochromic properties in an amorphous state can be formed into a thin film by a coating method by a spin coating method and is excellent in mass productivity. .

[0009]

However, the crystal film composed of a diarylethene compound described in Japanese Patent Application Laid-Open No. H08-119963 needs to be formed by a vacuum deposition method or the like, and is inferior in mass productivity, so that its practicality is low. There was a problem.

When a crystalline diarylethene compound is formed into a thin film by a coating method, the concentration of the diarylethene compound is limited to about 30% by weight because it is dispersed in a polymer resin medium, so that a high-quality film cannot be formed. there were.

The amorphous diarylethene compound described in JP-A-2000-256664 has a large change in absorbance and a large change in refractive index before and after light irradiation, but has a low glass transition temperature of about 68 ° C. and a high thermal stability. There was a problem that it was inferior.

Further, there is a problem that the amorphous diarylethene compound gradually crystallizes during use, causing deterioration of characteristics.

Accordingly, it is an object of the present invention to provide a photochromic compound comprising an amorphous diarylethene compound having a glass transition temperature of 100 ° C. or higher, and an optical functional device using the same.

[0014]

According to the present invention, there is provided a photochromic compound having a triarylamino group at a terminal, an asymmetric diarylethene compound containing a ring A, having a high glass transition temperature and exhibiting excellent properties. It is based on the knowledge that.

That is, it is represented by the chemical formula 1 and is characterized in that the refractive index is reversibly changed by light. However, in the formula, R ¹ and R ² represent hydrogen, an alkyl group, or an alkoxy group.
R ³ , R ⁴ , R ⁵ , and R ⁶ each represent hydrogen, an alkyl group, an alkoxy group, or an aryl group, and may be unsubstituted or partially substituted. 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. RA is an aromatic ring or a heterocyclic ring;
These include those having a substituent in part. X is oxygen,
Shows sulfur and nitrogen atoms. Ring A is an aliphatic ring, an acid anhydride,
A maleimide group.

Since the photochromic compound of the present invention has a triarylamino group at the terminal and a diarylethene skeleton having an asymmetric structure, the crystallinity is suppressed and the compound exhibits a stable amorphous state at room temperature. In addition, 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 change in optical characteristics. In addition, since the glass transition temperature is 100 ° C. or higher, the glass transition temperature is excellent.

Further, 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 crystal film.

Further, the optical functional device of the present invention is characterized in that a thin film comprising the photochromic compound of the present invention is formed on a substrate, and information is recorded by irradiating the thin film with light. Since a recording layer made of the photochromic compound having excellent optical characteristics is provided, a high C / N ratio can be obtained.

Further, in an optical functional device for optical switching comprising a core part on which light is guided on a substrate and a clad part provided around the core part, one of the core part and the clad part is provided. It is characterized in that a part thereof is composed of the photochromic compound of the present invention.
Since this optical functional element is formed of an amorphous thin film made of the photochromic compound of the present invention, which exhibits a large change in the refractive index upon irradiation with light, a small high-speed self-holding optical switching element can be realized.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The general formula of the photochromic compound of the present invention is represented by Chemical Formula 1, and can be produced by appropriately selecting from known methods.

In the formula, R ¹ and R ² represent hydrogen, an alkyl group or an alkoxy group. Preferred are lower alkyl groups, especially methyl, isopropyl and methoxy.

R ³ , R ⁴ , R ⁵ and R ⁶ each represent hydrogen, an alkyl group, an alkoxy group or an aryl group, and may be unsubstituted or partially substituted. 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.

RA is an aromatic ring or a heterocyclic ring, including those having a substituent in part. RAs may be the same or different from each other. That is, RA may include different cases. Furthermore, RA
May be unsubstituted or a part of RA may be substituted. The substituent is a hydrogen group, an alkyl group, a halogen group, a nitro group, an amino group, an alkoxy group, or a cyano group.

X represents an oxygen, sulfur or nitrogen atom. In particular,
A sulfur atom is preferred because the ring-closed diarylethene compound produced by the photoisomerization reaction has the highest thermal stability.

Ring A represents an aliphatic ring, an acid anhydride, or a maleimide group, and is a compound represented by Chemical Formulas 2 to 4, respectively.

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

In particular, a cyclopentene ring substituted with a halogen atom, particularly a fluorine atom, is preferable because the reactivity of the diarylethene synthesis reaction is improved and a good yield can be obtained.

The representative photochromic compounds of the present invention are shown in Chemical Formulas 5 to 26, but are not particularly limited as long as the general formula is a photochromic compound represented by Chemical Formula 1.

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

[0036]

Embedded image

[0037]

Embedded image

[0038]

Embedded image

[0039]

Embedded image

[0040]

Embedded image

[0041]

Embedded image

[0042]

Embedded image

[0043]

Embedded image

[0044]

Embedded image

[0045]

Embedded image

[0046]

Embedded image

[0047]

Embedded image

[0048]

Embedded image

[0049]

Embedded image

[0050]

Embedded image

[0051]

Embedded image

[0052]

Embedded image

Since the photochromic compound of the present invention has a triarylamino group at the terminal and a diarylethene skeleton having an asymmetric structure, the crystallinity is suppressed and a stable amorphous state at room temperature for a long period of time is suppressed. Show. 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 made of the photochromic compound of the present invention is an amorphous thin film composed of a single photochromic compound, unlike a dispersion film dispersed in a polymer matrix, and therefore has a light absorption coefficient, a refractive index, an optical rotation or a dielectric constant. The optical characteristics such as are also large in comparison with the dispersion film.

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 significantly, the conventional dispersion film at most 10 ^- whereas was ^three orders, if the photochromic film to align the photochromic molecule, the refractive index change of ^10-2 order. Further, since the switching is completed within a few nanoseconds, a high-speed response is possible.

Further, the photochromic thin film comprising the photochromic compound of the present invention can be applied by 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.

Further, the photochromic compound thin film obtained above can be used for an optical functional element such as an optical recording medium. As schematically shown in FIG. 1, the optical recording medium P
Reference numeral 1 denotes an amorphous thin film made of the photochromic compound of the present invention provided as a recording layer 2 on a disk-shaped substrate 1 made of, for example, a resin material such as polycarbonate having translucency, glass, or the like. It is possible to provide and configure.

The substrate 1 constituting the recording medium P1 is made of a plastic having a light-transmitting property (for example, polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin), glass or ceramic. , Metal and the like can be used.

The recording layer 2 is laminated to a thickness of about 100 to 5 μm (preferably 1000 to 1 μm), and a metal (A
u, Al, Ag, Cu, Cr, Ni, etc.) and metalloids (Si
And the like are laminated to a thickness of about 50 to 3000 (preferably 100 to 3000).

If the thickness of the recording layer 2 is smaller than the above range, no light sensitivity can 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 reflection cannot be obtained.

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

Further, as shown in FIG.
An optical recording medium P2 may be provided in which a recording layer 22 is provided on the recording medium 1, information is recorded by the incident light L11, and information is reproduced by detecting a difference in light transmittance between the incident light L11 and the output light L12.

As shown in FIG. 3, when the substrate 21 is opaque, the recording layer 2 is placed on the substrate 21 having a reflection function.
In the case of the optical recording medium P3 provided with 2, the information can be recorded by the incident light L21 and the information can be reproduced by the reflected light L22.

Note that these layer configurations are the minimum required configurations. For example, a reflective layer or a recording layer may be covered with a protective layer to form a multi-layer configuration.

The amorphous thin film made of the photochromic compound of the present invention can be suitably used, for example, in the optical transmission line of an optical switching device shown in FIG. Conventionally, in the case of optical switching using a photorefractive material, there was a problem that an electric charge had to be applied.However, when an amorphous thin film made of the photochromic compound of the present invention was used, light was not applied even when an electric field was applied. Since it can be controlled and held by itself, it can be operated without consuming energy.

In the embodiment of the present invention, a photochromic compound having a triarylamino group at a terminal represented by the chemical formula 1 and having an asymmetric diarylethene skeleton, and an amorphous thin film made of the photochromic compound are used as an optical recording medium. And the case where the present invention is applied to an optical switch element has been described, but the present invention is not limited to this. 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.

As described above, by using the photochromic compound of the present invention as a thin film, it is possible to realize an excellent optical functional element such as an optical recording medium and an optical switching element. Since the optical functional element of the present invention has the recording layer made of the photochromic compound exhibiting excellent optical characteristics, excellent device characteristics can be obtained.

[0068]

EXAMPLES Example 1 The photochromic compound represented by Formula 5 has maximum wavelengths at 303 nm and 336 nm in a hexane solution. The molar extinction coefficient is 49000 (303 nm) 5
It turned out to be a large value of 4000 (333 nm). Further, when the photochromic compound represented by the chemical formula 5 was irradiated with ultraviolet light having a wavelength of 313 nm,
The solution was colored blue and was observed near its absorption maximum of 598 nm.

As a result of DSC measurement, it was confirmed that each of the photochromic compounds represented by the chemical formula 5 had a glass transition temperature of 113 ° C., and the ring-closed compound of the chemical formula 5 obtained by the photoisomerization reaction had a temperature of around 134 ° C. Has a glass transition temperature.

After dissolving the photochromic compound represented by the chemical formula 5 in toluene, it is applied on a quartz substrate by a spin coating method, and baked at 90 ° C. to form a 1 μm-thick photochromic thin film (hereinafter referred to as a thin film 1).
Was made). In general, an organic thin film has a strong tendency to crystallize, and crystallizes when left for a long period of time, and the crystallized portion becomes a defect to cause deterioration in characteristics. However, it was confirmed that the thin film 1 was free from defects due to crystallization even after being left for more than half a year, 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 observed and it was confirmed that it was a uniform amorphous thin film.

When the thin film 1 produced as described above was irradiated with 313 nm ultraviolet light, the film was colored green. When the absorption spectrum of the thin film at this time was measured, 60
It was confirmed that it had an absorption maximum near 6 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.

The properties of the obtained thin film 1 were not degraded due to the deterioration of the compound, even when the photochromic reaction was repeated 10,000 times or more and the film was left for 500 hours or more at 80 ° C. in a dark place. Comparative Example 1 A thin film was prepared by a spin coating method using Formula 27 in which an ethyl group was introduced instead of the substituent (tolyl group) on nitrogen in Chemical Formula 5, and crystallization progressed quickly after the film was formed. No amorphous thin film was obtained.

[0073]

Embedded image

Comparative Example 2 A photochromic thin film (thin film 2) having a thickness of 1 μm was prepared by dispersing Chemical Formula 27 in PMMA at a concentration of 30% by weight. In the PMMA dispersion film, it was confirmed that when the concentration of the chemical formula 27 exceeded 30% by weight, the characteristics deteriorated. Example 2 A change in the refractive index before and after irradiation with ultraviolet light was examined for the thin films 1 and 2 prepared in Example 1 and Comparative Example 2 using laser beams of 633 nm, 817 nm, and 1550 nm.
With the progress of photochromic reaction by ultraviolet light irradiation,
It was confirmed that the refractive index increased. The refractive index difference between the state before irradiation and the light steady state is 2 × 10 ^{−3 in the} thin film 2.
On the other hand, the thin film 1 has an order of magnitude of 1.2 × 1
It turned out to be 0 ^-2 . 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 was greatly affected as compared with the PMMA dispersion system. Example 3 Using the thin film 1 of Example 1, an optical recording medium P1 shown in FIG. 1 was produced. A recording layer composed of the photochromic compound represented by Chemical Formula 5 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 an apparatus having a semiconductor laser of 400 nm and 680 nm mounted on a pickup. Recording was performed at a power of 10 mW with a 400 nm laser, and reproduction was performed at a power of 0.2 mW with a 680 nm laser. As a result, 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 An optical waveguide was manufactured using the thin film 1 obtained in Example 1,
The switching phenomenon was confirmed. A waveguide as shown in FIG. 5 was manufactured. On a substrate 111, core portions 112, 113,
Photochromic cladding 114 made of the photochromic compound thin film of the present invention, polymer cladding 115 having the same refractive index as the photochromic thin film, and coupler 1
16 are formed. 1.55 nm for the fabricated waveguide
It was found that, when ultraviolet light was applied and the refractive index was changed, light of 1.55 nm could be switched. In addition, it was found that the switching speed was higher than that of a waveguide made of a conventional dispersion film.

[0076]

According to the present invention, a photochromic compound comprising a diarylethene compound having a triarylamino group can form an amorphous thin film using the photochromic compound alone without being dispersed in a polymer matrix. Exhibit greater optical properties, especially large absorbance changes and refractive index changes compared to dispersion films.

Further, it has been found that the optical functional element using this has excellent device characteristics and can respond at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a structure of an optical recording medium P1 which is an optical functional element of the present invention.

FIG. 2 is a schematic sectional view illustrating an optical recording medium P2 which is an optical functional element of the present invention.

FIG. 3 is a schematic sectional view illustrating an optical recording medium P3 which is an optical functional element of the present invention.

FIG. 4 is a perspective view schematically illustrating an optical waveguide according to the present invention.

FIG. 5 is a schematic plan view illustrating an optical waveguide according to the present invention.

[Explanation of symbols]

 1, 11, 21, 111 ... substrate 2, 12, 22 ... recording layer 3 ... reflection layer P1, P2, P3 ... optical recording medium L1, L11, L21 ... incident light L2, L22: Reflected light L12: Outgoing light 113, 112: Core part 114, 115: Cladding part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G02F 1/361 G02F 1/361 1/365 1/365 G11B 7/24 516 G11B 7/24 516

Claims (3)

[Claims] 1. An aliphatic ring represented by the formula (1):
Product, containing a ring A consisting of either a maleimide group or
Therefore, the refraction index changes reversibly.
Tochromic compound. Embedded imageWhere R¹, R^TwoIs hydrogen, alkyl group, alkoxy
Represents a group. R^Three, R^Four, R ^Five, R⁶Is hydrogen, alkyl
Group, alkoxy group or aryl group, which may be unsubstituted
May be partially substituted. Alkyl as a substituent
Group, aryl group, halogen group, nitro group, amino group,
There are an alkoxy group and a cyano group. RA is an aromatic ring or
And those having a substituent in part.
X represents an oxygen, sulfur, or nitrogen atom. 2. An optical functional device comprising a thin film made of the photochromic compound according to claim 1 formed on a substrate, and recording the information by irradiating the thin film with light. 3. An optical functional device for optical switching comprising a core portion on which light is guided on a substrate and a cladding portion provided around the core portion, wherein one of the core portion and the cladding portion is provided. An optical functional device comprising a part of the photochromic compound according to claim 1.