JPS62165647A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enable the nondestructive optical writing and readout of informa tion by using a complex of a transition metal selected among specified compounds as at least one between an electron donative substance and an electron accepting substance. CONSTITUTION:A complex of a transition metal capable of producing a mixed valence state and represented by formula I, II or III is used as at least one between an electron donative substance and an electron accepting substance. In the formulae I-III, Z is O, S or NR (R is H or alkyl), each of X and X' is H, alkyl or the like, Z' is S or NR (R is H or alkyl), Y is H, alkyl or the like, m is an integer of +2--2, A is an anion, a cation or a group of anions or cations having electric charges required to neutralize electric charges defined by m, and M is an ion of a transition metal. Thus, light for readout can be completely distinguished from light for writing, so destructive readout is avoided in principle.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to optical recording media.

(Prior Art) Optical recording systems are a field of active development because they allow inexpensive, large-capacity recording media to be obtained. Conventionally, in this field, an inorganic metal thin film is used as a recording film, and the near-infrared output of a semiconductor laser is converted into heat, and the heat is used to make a hole in the recording film or to cause a phase change to change the surface. A so-called heat mode optical recording method that reads changes in reflectance has been put into practical use. Furthermore, in recent years, a new heat mode optical recording method using an organic dye as a recording film has been proposed. but.

Optical recording methods using heat mode have a limit in sensitivity because heat is dissipated through the substrate etc. when converting the output of a semiconductor laser into heat, and methods based on hole-drilling have a limited ability to erase information. Have difficulty. From these points of view, as a method to prevent the absorbed light from dissipating as heat and preventing deformation of the recording film, it is possible to use the absorbed light as it is as photon energy and use the subsequent photoreactions to record and reproduce information. A photon mode optical recording method has been proposed and is being actively researched as a means to obtain reversible optical recording materials that can erase information. For these purposes, proposals have been made to use photochromic materials as recording film materials.
JP-A-59956 proposes a spiropyran derivative having a linear alkyl group, and JP-A-60-123838 proposes a chemical vapor deposited film of a similar spiropyran compound as a recording layer. Also, for the same purpose, Hella (A
J. Chem, Soc.
I'erkin 1), p. 202 (1981) describes the properties of a photochromic compound called flucyto and its application to optical recording materials. Various methods have been proposed for optical recording of these compounds, but in general, photochromic compounds such as spiropyrans and flucyto compounds are initialized by irradiating the entire surface with ultraviolet light to strongly color them. .

Information is recorded and read out by irradiating visible light that matches the color change range of the photochromink compound. These are generally carried out in the ultraviolet to visible light range, but recently there have been publications on spiropyrans that match the oscillation wavelength range of semiconductor lasers (for example, in Proceedings of the 50th Spring Annual Meeting of the Chemical Society of Japan, 1.
P2S5 (1985)) has also been made.

(Problems to be Solved by the Invention) However, one of the problems when using conventional photochromic and mink compounds as optical recording materials is that these photochromic compounds destroy information when read. This is because the initial state and colored state of photochromic compounds have common or crossed excited states with a high probability, and information can be recorded by irradiating the absorption of nine colored species with light, and later by readout light. This is because reading information leads to the same excitation state and read destruction is unavoidable. A method to avoid this problem is to weaken the light intensity of the readout light, but since optical excitation itself is the only reaction process, it is impossible to differentiate by threshold value, and the probability of K is always constant. read corruption may occur.

Problems arise when reading information repeatedly.

(Means for solving the problems) The present invention has been made in view of these problems,
Unlike traditional photochromic materials.

An object of the present invention is to provide an optical recording medium on which information can be recorded and reproduced without causing reading damage.

The present invention provides an optical recording medium containing a photosensitizer, an electron-donating substance, and an electron-accepting substance, and at least one of the electron-donating substance and the electron-accepting substance is a substance capable of taking a mixed valence state. Regarding the medium.

In the optical recording medium of the present invention, a photosensitizer is used as a molecule for recording by writing light, an electron donor substance and/or an electron acceptor substance is used as a reading molecule, and they are in a photoexcited state of the photosensitizer. The reaction product that transfers electrons from an electron-donating substance to an electron-accepting substance through the interaction of .

Read corruption can be avoided in principle. This is illustrated in FIG. 1 (1). In FIG. 1(1), the photosensitizer S becomes an excited type photosensitizer S'' by the writing light.

S" is active and transfers electrons to the electron-accepting substance A to become oxidized S+□ and reduced A-", respectively. S
+- is still active and subsequently reacts with the electron donating substance to give its oxidized form D+-, which itself becomes S and regenerates the photosensitizer. At this time, non-destructive reading is achieved by optically reading the physical and optical changes that occur in at least one of D+□8- at a wavelength different from the wavelength used for previous writing. Ru. In addition, Figure 1 (
2) distinguishes a slight difference in reactivity under a transition state, and although there is no essential difference from (1) in FIG. 1, it is important when considering reversibility. Such photosensitized redox reactions have been known for a long time. For example, for the purpose of a water photolysis reaction, a system was used in which triethanolamine was used as an electron donating substance, ruthenium + IJ subbiridyl complex was used as a photosensitizer, and methyl viologen was used as an electron accepting substance. Accumulation of methyl viologen cation radicals (Daretzzel (M.

Vol., p. 701 (1979)), or the dimethylaniline-porphyrin-naftquine system (M., Wasie Iewski et al., Journal of the American Chemical Society (J.
, Amer.

Chem, Soc, Volume 107, Page 5562 (19
85)) have been reported. However, in such reported examples, the products after charge separation are extremely unstable and generally have a short lifetime.

It is impossible to use it as a recording material. This is partly because the product is unstable, reacting with other molecules or changing itself, or because the state after charge separation is unstable, causing charge recombination through a reverse reaction. This is the biggest cause. In order to overcome this problem in the present invention, one or both of the electron-donating substance and the electron-accepting substance in the photosensitized redox reaction is a substance that can take a mixed valence state. . Here, the mixed valence state refers to a state in which a plurality of neutral or charged states exist or are mixed. In substances that can have mixed valence states, two or more oxidation states exist in one substance,
These can exist stably or metastablely. Further, these different oxidation states may exist independently or coexist.

Therefore, there is no problem in the thermodynamic stability of the charge-separated products before and after light irradiation. Furthermore, the use of substances that can have mixed valence states may be a clue to solving other kinetic stability problems.

In general, the redox potential of a substance that can have a mixed valence state is concentrated in a narrow range, and the range becomes even narrower when taking into account the conditions under which both oxidation states can exist stably even in the atmosphere. A comparison of light irradiation in such a system and light irradiation in other general systems is shown in FIG. In FIG. 2, (1) is a general light irradiation system.

Normally, photochemical reactions involve the accumulation of light energy in some sense, as in the reaction examples listed above.

The aim is to store and convert light energy (solar energy). The product is therefore in a high energy state, which results in the instability mentioned above.

In addition, in general, the redox potential difference between the electron donating substance and the electron accepting substance after charge transfer is large (usually 1.0 V or more), which tends to promote the reverse reaction kinetically as well as thermodynamically. are doing. In contrast, in the present invention, by using a substance that can take a mixed valence state as an electron donating substance and/or an electron accepting substance, it is possible to reduce the energy difference between the electron donating substance and the electron accepting substance. can. Figures 2 (2) and (3) illustrate this state, and even after light irradiation, high energy is not accumulated in the system, contributing to the stability of the system. In addition, the energy difference between electron-donating and electron-accepting substances is small (approximately 1.Oe
V), which slows down the reverse reaction rate. In particular, if this difference is made small (within 0.5 eV), the driving force of the reverse reaction itself becomes small, which greatly contributes to the stability of the system. Figure 2 (3) is an extreme example, and in this system thermodynamically there is no need to use light and the reaction can proceed spontaneously, but it is possible to control electron transfer using light. This shows that it is possible. In this way, the stability of such a photosensitized redox system can be greatly improved by simply providing a switching effect during writing without accumulating much optical energy.

It becomes possible to use it as a recording material. Note that dynamic stability is not just a matter of energy level, but can also be controlled by the environment of the system, which we will return to later.

Means for optically reading the physical and optical changes that occur in the system due to such photosensitized redox reactions include changes in refractive index, changes in attractive index, and changes in reflectance.

Although there are various changes such as changes in transmittance, it is preferable to read changes in light reflectance or light transmittance because the detection means is easy.

In addition, the physical and optical changes that occur in the electron-donating substance and/or the electron-accepting substance, especially changes in light reflectance and light transmittance, are within a range that does not overlap with the light absorption area of the photosensitizer during writing. If so, it may occur in any particular wavelength region, but it is particularly preferable that it occur in the near-infrared region. In this region, a semiconductor laser can be used for readout, so the system can be simplified. In addition, current optical discs use semiconductor lasers for writing and reading in this area, so these existing technologies can be used.

It is extremely important to ensure compatibility in reading information from recording media. The near-infrared region here is 70
0 nm to 1600 nm, preferably 750 nm
nm to 1100 nm. It is important to maintain a range of absorption in the near-infrared region in this way when considering multiplexing of information.

Examples of electron-donating substances and/or electron-accepting substances that satisfy the above characteristics include organic dyes, organic pigments, inorganic pigments, transition metal complexes, and the like.

Transition metal complexes are particularly desirable as substances capable of obtaining mixed valence states. This is because transition metal complexes tend to exhibit characteristic absorption in the near-infrared region, in combination with the fact that transition metal complexes take nine different valence states depending on the valence of the metal and interaction with ligands. It is also important that many of these substances are thermally stable.

Compounds represented by the following general formula (11, (I[) or I) are preferred.

In 2(I) and (Ill, Z is 0.S and NR
,(R.

is an atom or atomic group selected from hydrogen or an alkyl group, and may be different at each position;

and X' is selected from hydrogen, an alkyl group, a substituted alkyl group, a halogen group, an alkoxy group, an alkylamino group, a nitro group, and/or a cyan group, X and X' may be the same, and n is an integer of 1 to 4. 9m is an integer from +2 to -2, A is an anion or cation or a group thereof having the number of charges required to completely neutralize the charges defined by m, and M is a transition metal ion (however, when 9m is 0, A does not exist).

In formula (n), Z' is selected from S and NR, (R is hydrogen or an alkyl group) and may be different at each position.
, Y is hydrogen, an alkyl group, or a substituted alkyl group.

The phenyl group may be selected from substituted phenyl groups and cyano groups and may be different at each position (m is an integer from +2 to -2,
A is an anion or cation having the number of charges necessary to neutralize the charge defined by m, or a group thereof, and M
represents a transition metal ion (however, if m is 0, A
does not exist).

A, Mceverty) et al., Prodales Inorganic Chemistry (Prog, Inorg
, Chem, ) vol. 10, p. 49 (1968), Schrauzer et al., Accounts of Chemical Research (Acc, Chem, Re).
s,) vol. 2, p. 72 (1969), Inorganic Synthesis (Inorg, Syn,) vol. 10, 2
The synthesis method and properties are summarized in detail on page 1. Under normal conditions, it can be stably isolated in the air as a zero-valent neutral substance from a mono-divalent anion, and its charge state depends on the type of central metal ion. , depends on the type of ligand. Various oxidation states have been confirmed for all or part of the range from divalent anions to divalent cations in these compounds,
It is known that some of them can be stably isolated in air in different oxidation states. For example, the following compound 1 is a nickel bis(dithiomaleonyl) complex.
Regarding 1a, the following complex 1 [a le na
2 have been isolated.

exhibit different physical properties.

a7. These are stable in the air and in solution, and both have a redox potential of +〇, 23V (vs. saturated calomel electrode, hereinafter vs.
(abbreviated as scE), they are mutually converted by electrically and chemically reversible redox reactions.

This is accompanied by a significant change in the absorption coefficient in the near-infrared region. Similar reactions can be found among these groups of compounds. For example, platinum bis(dithiomaleonitrile)
Dianion complex → monoanion complex, nickel bis(dithiostiben) complex (nb-1) - nickel bis(dithiostiben) monoanion complex (nb-2) [nickel bis(0-)unilene diimine) complex] 0(
Examples of suitable compound complexes include cobalt bis(dithiomaleonitrile) complex. +M bis(dithiomaleonitrile) complex, iron bis(dithiomaleonitrile)
complex and its dimer, nickel bis(drenin 3.4
dithiole-1m form, platinum bis(toluene & 4 dithiolate) complex, nickel bis(4-dimethylami 4 dithiolate) complex, nickel bis(3,4,5,6 tetrachlorobenzenedithiolate) complex, nickel bis(1,2 -dithionaphthalene) complex, platinum bis(1,2-si+onaphthalene) complex, palladium bis(dithiomaleonitrile) complex, platinum bis(dithiostriven) complex, palladium bis(dithiostriven) complex.

Nickel bis(p,p'-dichlorodithiostriven)
complex, nickel bis(p, p'-dimethoxydithiostilibene) complex, platinum bis(p, p'-dichlorodithiostiben) complex, nickel bis(tolylene λ4 diimine) complex, nickel bis(1,2- xylene-3,4-diimine) complex, nickel bis(4-chloro-1,2-7
22 diimine) Complex* Platinum bis(1,2-phenylenediamine) complex, nickel bis(diimino maleonitrile) complex, platinum bis(diimino maleonitrile)
complex, nickel bis(bis(trifluoromethyl)ethylene dithate), nickel bis(ethylene dithate) complex.

Examples include platinum bis(bis(trifluoromethyl)ethylene dithate) complex. These should be ultimately selected taking into account the type of system, absorption maximum position9, redox level of the redox pair to be combined, etc., but the reaction at the first redox potential of the various oxidation states It is desirable to select with consideration to the stability of the β compound. Further, the redox potential at that time should be determined based on a combination of factors.

The redox potential is -0.5V to +0.8V (vsSC
E) It is preferably in the range of -0.2V to +0.5V. This range is particularly preferably OV~
This is because both oxidation states at +0.4■ can exist stably in the atmosphere and in the presence of a solvent. Of course, this does not apply when measures such as sealing the system are taken.

Although the transition metal complexes listed above give suitable results, other substances that can have mixed valences are also considered. Other examples include blue cyan backs, iron-sulfur cluster compounds, nickel bis(duroquinone) complexes, and the like. In addition, when used in combination with these substances that can have mixed valences,
Other conventional electron-donating or electron-accepting substances may also be used.

Triethanolamine is an electron donating substance.

Ethylenediaminetetraacetic acid and the like can be mentioned, and examples of quinones such as 1,4-benzoquinone, 1.
Examples include 4-naphthoquinone, duroquinone, chloranil, etc., and these electron-donating substances or electron-accepting substances are generally highly active.

When the difference in redox potential between the substances to be combined and the substances that can take a mixed valence state is too large, for the reasons mentioned earlier, the choice should be made carefully to ensure that a reverse or forward reaction occurs quickly depending on the difference. It is. Furthermore, when these are used, the products are generally not stable and irreversible changes occur subsequently due to other reactions, which poses an undesirable problem when considering reversibility.

The photosensitizer used in the present invention has a redox potential at its base energy level that is lower than the redox potential of the electron donating substance, and a redox potential at its excitation energy level that is lower than the redox potential of the acceptor substance. It only needs to be higher than the potential. In the present invention, for the reasons stated above, the redox potential difference between the electron donating substance and the electron accepting substance is not very large, so the photosensitizer that satisfies this relationship covers a range of light from ultraviolet light to near-infrared light. Although it is possible to have absorption in a wide range, it is selected so as not to overlap with the absorption possessed by the electron donating substance and/or electron accepting substance or with the new absorption generated after the electron transfer reaction.

Among these, photosensitizers made of dyes or pigments having absorption in the visible to near-infrared region are preferred because various lasers such as gas lasers, dye lasers, semiconductor lasers, etc. can be used as light sources.

Among them, thiazine dyes and oxazine dyes.

Xanthine dyes, porphyrin dyes, tetrathroline complexes, and 7-talocyanine compounds are particularly preferable because they have excellent ability as photosensitizers and also have high photostability. Examples of photosensitizers are:

Thionin, methylene blue, methylene violet, cresyl violet, resorufin, Nile blue, erythrosin B, eosin Y, eosin-B, methyleosin, flocsin B, rhodamine B, rhodamine 6
G, Rose Bengal, 2,3゜7, al 2,
13, 17, 18. - Octa x + h - 21) 1゜23H
-Porphy 7, 2, 3, 7. al 2, 13, 17.
1 a-octaethyl-21H,23H-porphine cobalt complex, 2,3,7,8,12.1λ17.18.
-Octaethyl-21H,23H-porphine magnesium complex, 2,3,7,8,1,2.1 Formula 17,1
8. -octaethyl-2LH,23H-porphine nickel complex.

λ3.7.8.1 S1 Mi17. la-octaethyl-2
1H,23H-porphine manganese complex, 5,10゜1
5.20-tetraphenyl-21H,23H-porphine, 5,10.15.20-tetraphenyl-21H,
23H-porphine zinc complex, 5,10°15,20-
Tetraphenyl-21H,23H-porphine magnesium complex, 5.10,15.20-tetraphenyl-2
1H,23H-porphine iron chloride complex, 5,10,1
5.20-tetraphenyl-21H,23H-porphine cobalt complex, 5,10゜15,20-tetraphenyl-21H,23H-porphine-nickel complex, 5,
10.15.20-tetrakis(2-pyridyl)-21
H,23H-porphine, 5,10,15.20-tetrakis(4-pyridyl)-2LH,23H-porphine, 5,10゜15.20-tetrakis(4-dimethylaminophenyl)-21H,23H-porphine, Ruthenium tris(2,2'-bipyridyl) complex, osmium tris(42'-bipyridyl) complex, rhodium tris(
2,2'-bipyridyl) complex, rhodium tris(1,1
0-phenanthroline) complex, ruthenium tris(1,
10-phenanthroline) complex, osmium tris(1
, 10-7 enanthroline) complex.

29H,31H-phthalocyanine, zinc phthalocyanine, magnesium phthalocyanine, manganese phthalocyanine, vanadyl phthalocyanine, tetraamino-29H,
Examples include 311-1-phthalocyanine, copper-phthalocyanine, iron phthalocyanine, silicon phthalocyanine, and the like.

In carrying out the present invention, the above-mentioned photosensitizer.

An electron-donating substance and an electron-accepting substance are added together with other necessary additives, but each substance should be selected with due consideration given to the relationship between the redox potentials of these substances. At this time, for the reasons mentioned above, undesirable electron transfer due to reverse or forward reactions is minimized by selecting the difference in redox potential between the electron donor and electron acceptor substances to be as small as possible. It can be suppressed. Example Eva, nickel bis(1,2-7 2-2-dienedimine (oxidation-reduction potential +〇, 12 V vsscE)
The electron-donating substance, nickel bis(dithiomaleonitrile) monoanion (oxidation-reduction position +0.23V vssc
When E) is used as an electron-accepting substance, the redox potential difference between the two is 0. IV, which can cause a forward electron transfer reaction without irradiation with light, but the redox potential difference is only 0. Since it is IV, the electron transfer reaction in solution is slow, and the reaction proceeds only gradually over a period of several days to several weeks. Therefore, the stability in high viscosity media and solid phase is practically sufficient. Furthermore, thermodynamic instability based on the redox potential difference between these electron-donating substances and electron-accepting substances can also be controlled by other factors such as the method of dispersing these substances in the dispersion medium 9 . Among them, a particularly effective method is when mixing.

This results in some degree of heterogeneity, with substantial separation of the electron-donating and electron-accepting materials. "Substantially separated" here means that the free diffusion of the electron-donating substance and the electron-accepting substance is restricted.

This includes, for example, a system in which non-uniformity is provided in the dispersion medium and electron-donating substances and electron-accepting substances exist in different correlations. Such systems include micelle systems, systems with artificial interfaces such as ribosomes, and dispersion in media having phase-separated morphology such as polar-nonpolar block polymers. Another effective means is to form a laminated structure in which an electron donating substance, a photosensitizer, and an electron accepting substance are laminated in this order. In this case, the intermediate photosensitizer-containing layer is a layer between the electron-donating substance, the electron-accepting substance, and V). It exists as a δ layer and a thin layer, and at the same time functions as a layer that transfers electrons using the photoexcitation process of a photosensitizer to an electron-donating substance and an electron-accepting substance.

For this purpose, it is desirable that the intermediate layer containing the photosensitizer has an appropriate thickness, and the thickness is 50X.
~1oooX is appropriate. If the film thickness is less than 50X, it will not work effectively as a layer, and if it exceeds 1000, the movement of electrons in the intermediate layer will be hindered.
This is because the injection efficiency of electrons from the layer containing the electron donating substance to the layer containing the electron accepting substance is significantly reduced. A method for manufacturing such a laminated structure is the coating method.

Various existing film forming methods such as a dipping method, a vacuum evaporation method, a sputtering method, and an LB patterning method can be used.

In the present invention, the recording layer containing a photosensitizer, a child-donating substance, and an electron-accepting substance may be self-supporting, but is preferably formed on a transparent substrate.

As the transparent substrate, inorganic glasses such as 9-quartz glass and silicate glass, and plastic substrates such as polymethyl methacrylate resin, polycarbonate resin, and epoxy resin are used. A tracking groove, a conductive electrode, etc. may be further formed on the substrate with the recording layer sandwiched therebetween. By providing a conductive electrode and applying an appropriate potential between the electrodes, it is also possible to perform a reverse reaction on the electrons transferred to the electron-accepting substance, thereby erasing information.

Moreover, it is preferable to use a substrate in which a reflective layer is further formed on the substrate. By providing the reflective layer, the amount of reflected light between the signal recording area and the non-recording area is significantly different, making detection easier. The reflective layer is provided on the top or bottom surface of the recording medium. The material of the reflective layer is suitable for writing light and reading light.

Any material may be used as long as it has an appropriate reflectance.

Usually, a thin film of metal such as aluminum, chromium, nickel, or gold is used. These are formed by known means such as vacuum deposition.

The recording layer contains a photosensitizer, 1! It may be composed only of a child-donating substance and an electron-accepting substance, or it may be dispersed in another dispersion medium or the like. Various polymers are suitable as the dispersion medium, and these include the photosensitizer used, 'l!
Child-donating substances, 1! An appropriate one is selected in consideration of the type of child-accepting substance, its redox potential, solubility, etc. In addition, other additives may be contained in the recording layer for various purposes, but these may have an adverse effect on the redox levels of the electron-donating substances and electron-accepting substances used and the relationship between them. It should be selected and used to the extent that it does not affect the environment.

Examples of additives include dispersion stabilizers such as surfactants, organic or inorganic fillers, metal powders, and the like.

Furthermore, these electron-donating substances! There is no particular limit to the blending ratio of the bone-tolerant substance and the photosensitizer.

Preferably, the electron donating substance and the electron accepting substance are present in approximately equimolar amounts. Also, photosensitizers.

It is preferable to mix the catalyst in an amount of equal to or more than the same mole, taking into account the reaction rate, extinction coefficient, etc. of the reaction system.

The present invention is applicable to various optical recording media based on optical recording methods, and is particularly applicable to information recording fields such as optical discs and display elements.

The present invention will be explained below with reference to Examples. Parts are by weight.

Example 1 The following experiment was conducted on an optical recording medium according to the present invention. 5.10.15.20-tetraphenylporphine zinc complex (hereinafter abbreviated as ZnTPP) was used as a photosensitizer, and a neutral salt of nickel bis(1,2) unilene diimine) (hereinafter [N1 (PDA)2]O), nickel bis(dithiomaleonitrile) monoanion tetrabutylammonium (abbreviated as
The following (abbreviated as Ni (MNT)z]-.TBA+) was used. Both perform the following redox reactions, respectively.

The redox potential at that time is also shown.

+ 0.23 V vs 8CE 10, 12V vsscE When nickel bis(dithiomaleonitrile) monoanion is reduced to dianion, the absorption near 850 nm changes from an allowed transition to a forbidden transition, resulting in a significant change in the extinction coefficient (approx. 102 order) changes. This quantum chemical explanation was published by H. B. Gray et al. in the Journal of the American Chemical Society (J. Amer. Chem.
Sac, Vol. 86, p. 4594 (1964). Similarly, when nickel bis(1,2-)unilene diimine) is oxidized to become a cation, its absorption maximum at 780 nm (10 gξ~4.5) is greatly reduced.

Therefore, C Ni (PDA)2 which is an electron donor]
0 to electron acceptor (Ni(MNT)2]-TBA
Absorption in the near-infrared region decreases due to the movement of electrons to ±.

(1) Sample preparation CNi (PDA)2 ]0 1
eB DMF solution 1 or more components were placed in a quartz cell with a 1 cm optical path together with a stirring rotor, and after nitrogen gas was passed through the cell, the cell was tightly stoppered. At the same time, a control cell having the same solvent composition was prepared.

(2) Light irradiation experiment: 500 nm passing through a cyan blue filter and a Y-48 filter, limiting the passing wavelength to approximately 500 nm to 55 Q nm.
Light irradiation was performed using a W xenon lamp as a light source.

The irradiation was carried out at room temperature with stirring using a magnetic stirrer. 9 minutes before irradiation and every 5 minutes from the start of irradiation.
Changes in absorbance were measured using a UV-visible spectrophotometer U-150-20 manufactured by Hitachi. The results are shown in Figure 3.

In Figure 3, the absorbance curve at the initial stage of 1 digit, 2 digits after 5 minutes of light irradiation, 3 after 10 minutes of light irradiation, 4 after 15 minutes of light irradiation, 5 after 20 minutes of light irradiation, and 6 after 25 minutes of light irradiation. The absorbance curve after minutes is shown.

FIG. 3 shows that the absorption at 7801m decreases and the absorption near 45Qnrn increases due to light irradiation. The latter absorption band is CN i (MNT )2 :]”
-, and from this result, by light irradiation, (Ni (PDA)z)' to (: Ni (MN
Electron transfer to T)2:)- occurs, respectively to CNi
(PDA)z)", [:Ni(MNT'h12-).

(3) Supplementary experiment There is a strong relationship between the redox potential shown above and Ni (~fNT).Therefore, the reaction shown previously is via the photoexcitation process of ZnTPP used as a sensitizer. In order to demonstrate this, the sample from which ZnTPP was removed was subjected to a change in absorbance when left in a dark place and an experiment of light irradiation under the same conditions as in (2).

As a result, it was found that thermodynamically expected redox reactions also occur in the dark, but the rate of decrease in absorbance was extremely slow compared to the result in (2), and the rate of decrease in absorbance was extremely slow compared to the result in (2). It had a half-life. or.

No change in absorbance was observed within the light irradiation time range (20 minutes). Combining the above results, this reaction shows that ZnTP
It is concluded that this is a redox reaction corresponding to FIG. 2 (3) via the photoexcited state of P.

Example 2 Light irradiation was performed in the same manner as in Example 1 using the following composition.

However, as a filter, a cyan blue filter, Y-4
R-62 (manufactured by Toshiba Glass) was used instead of the 8 filter, and the reaction was carried out using light with a wavelength longer than about 620 nm.

Figure 4 shows the change in absorbance at 780 nm of the sample after light irradiation.

(C4H9)4N" 0.6 ml! lXl0-'mole/J dimethylformamide (DMF) solution of zinc phthalocyanine 0.2 ml (C4H9)4
N Cl0a IXI O-3mole/if: D
1 ml of EF solution In this reaction, the absorption band due to zinc phthalocyanine, which has an absorption maximum near about 57 Q nm, was not affected by light irradiation. Dark reaction in this system (system without sensitizer)
The half-life of the drug was more than 7 days, and a significant acceleration effect was observed by light irradiation.

Example 3 0.04 part of nickel bis(3,4-)lylene diimine), 0.1 part of p-benzoquinone, and 1 part of polymethyl methacrylate were dissolved in 5 parts of benzene, and further diluted with methane-jpv.
-o, oi parts*An acetone solution (approximately 4 m) of 0.1 part of tetrabutylammonium verchlorate was added.

This is a Pyrenx glass plate (thickness 1.0mm)
It was applied by spin coating and dried at 60°C for 10 minutes. The above operations were performed in the dark. The film thickness was approximately 1 μm. This product was irradiated with a 500WXe lamp for 5 minutes through a Y-48 filter. By light irradiation, the light transmittance at 780 nm increased approximately twice.

Example 4 0.05 part of nickel bis(dithiostiripen).

DM 0.1 part of penzoquinoi, 0.02 part of magnesium tetraphenylporphine, 0.1 part of tetrabutylammonium verchlorate, and 1 part of polyvinylpyrrolidone.
It was mixed with the FS part and dissolved. Example 3
Coat it on a Pyrex substrate in the same way as above, and the film thickness is about 1.5μ.
A dry coating film of m was obtained. The results of the light irradiation experiment monitored at 780 nm through a Y-48 filter are shown in FIG.

Example 5 A solution consisting of 0.02 part of nickel bis(1,2-7 2-dilene diimine), 0.5 part of tetrabutylammonium barchlorate, 0.2 part of polyvinylpyrrolidone, and part of DMFS was placed on a cleaned white slide glass substrate. was applied by spin. Zinc tetraphenylporphyrin was then vacuum deposited onto this to a thickness of about 5 ooA. Furthermore, a solution consisting of 0.5 parts of platinum bis(dithiomaleonitrile) monoanion tetrabutylammonium, 0.8 parts of polymethyl methacrylate, and about 5 parts of methyl ethyl ketone was spin-coated onto this and dried. This product was irradiated with light under the same conditions as in Example 1. The results are shown in Figure 6.

Even when this was left in a dark place, almost no change in absorbance due to the dark reaction as seen in Example 1 was observed.

As shown in FIGS. 4 to 6, it was observed that the absorbance at 780 nm decreased by light irradiation, and it is presumed that a mixed valence state occurred.

(Effects of the Invention) According to the optical recording medium of the present invention, writing and reading of information are all performed non-destructively using light, and materials with a wide wavelength range can be used. A wide range of designs can be made to suit the vessel. Furthermore, by shifting the absorption wavelength of the materials used, it is expected that the method will be applied to multiplex recording.

[Brief explanation of drawings]

Figure 1 (1), (21 is a schematic diagram explaining the movement of electrons caused by photoexcitation in the present invention. Figure 2 fl+, (2), (3) is a schematic diagram explaining the flow of electrons in the present invention Figures 3 and 4 are diagrams showing changes in absorbance in a system according to an embodiment of the present invention, and Figures 5 and 6 are diagrams showing changes in absorbance of a recording medium in an embodiment of the present invention. Agent Patent Attorney Kunihiko Wakabayashi 1st Wavelength (3rd Wavelength)

Claims (1)

[Scope of Claims] 1. A substance containing a photosensitizer, an electron-donating substance, and an electron-accepting substance, and in which at least one of the electron-donating substance and the electron-accepting substance can be in a mixed valence state. An optical recording medium. 2. The optical recording medium according to claim 1, wherein at least one of the electron-donating substance and the electron-accepting substance is a transition metal complex capable of having a mixed valence state. 3. Claims in which at least one of the electron-donating substance and the electron-accepting substance is a transition metal complex selected from compounds represented by the following general formula (I), (II), or (III). The optical recording medium according to item 1 or 2. (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In formulas (I) and (II), Z is O, S, and NR.
(R is hydrogen or an alkyl group) and may be different at each position, X and X' are hydrogen, an alkyl group, a substituted alkyl group, a halogen group, an alkoxy group, an alkylamino group , a nitro group, or a cyano group, and X and X' may be the same, n is an integer of 1 to 4, m is an integer of +2 to -2, and A is an integer that neutralizes the charge defined by m. An anion, a cation or a group thereof having the required number of charges and M represent a transition metal ion (provided that if m is 0, A is not present). (III) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In formula (III), Z' is selected from S and NR (R is hydrogen or an alkyl group) and may be different at each position, and Y is hydrogen. , an alkyl group, a substituted alkyl group, a phenyl group, a substituted phenyl group, and a cyano group, and may be different at each position, m is an integer of +2 to -2,
A represents an anion or a cation or a group thereof having the number of charges required to neutralize the charge defined by m, and M represents a transition metal ion (however, when m is 0, A does not exist). 4. The optical recording medium according to claim 1, 2 or 3, wherein the electron donating substance and the electron accepting substance are substantially separated. 5. Claims in which the optical recording medium is one in which an electron-donating substance or a layer containing the same, a photosensitizer or a layer containing the same, and an electron-accepting substance or a layer containing the same are laminated in this order. The optical recording medium according to item 1, 2, 3, or 4. 6. Claim 1 in which the optical recording medium has a reflective layer
2. The optical recording medium according to item 2, item 3, item 4, or item 5.