JP2012056861A - Photochromic compound, postscript type optical recording molecule material, display material, and fluorescence label material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photochromic compound which excels in recording retentivity and durability, and is useful as a high sensitivity optical recording medium without the volume change at the time of information recording, and to provide a postscript type optical recording molecule material, a display material and a fluorescence label material using the same.SOLUTION: The photochromic compound is expressed by general formula (1). In the formula, X is hydrogen, a halogen, a cyano group, a 1-5C linear or branched alkyl group, a 1-5C alkoxy group, or a substituent chosen from the group consisting of CHCOO-; Z is an alicyclic compound of a five-membered ring (atoms other than carbon may be included in the ring), or a heteroaromatic five-membered ring; Rand Reach independently denote a hydrogen atom, a 1-3C alkyl group or alkoxy group, a halogen element, a cyano group, or a formyl group; and Pdenotes a phenyl group.

Description

  The present invention relates to a photochromic compound, a write-once optical recording molecular material using the same, a display material, and a fluorescent label material.

  In a conventional optical recording medium, a photoresponsive dye is dispersed in the recording medium, and information is recorded and reproduced by utilizing a thermal degradation reaction of the dye. In other words, by irradiating a thinly focused light beam onto the recording medium, the thermal energy of the light beam is used to change the reflectance and refractive index of the irradiated part, and the difference between the irradiated part and the non-irradiated part is utilized. Yes. Such a heat mode recording method uses heat energy of a light beam, and therefore has low energy efficiency. There are also problems in terms of S / N ratio, recording density, and durability.

  On the other hand, an optical recording medium using photochromism of a photochromic compound has been proposed (Patent Document 1). Photochromism is a phenomenon in which a single molecule recombines chemical bonds by light irradiation, thereby reversibly generating two isomers having different absorption spectra. In an optical recording medium using photochromism, changes in color tone of two isomers are recorded as information. Since these two isomers have different absorption spectra, it is possible to reproduce information by detecting the difference between the light absorption intensity at a predetermined wavelength in the production state of one isomer and the light absorption intensity in the other state. Become. In general, the two isomers consist of a colorless ring-opened body and a colored ring-closed body, and the ring-closed body is produced by irradiating the ring-opened body with light.

Patent Document 2 proposes a thermally irreversible reverse photochromic compound in which the bonding position of the ethene moiety and the aryl moiety is 2-position as the sulfone-type diarylethene-based photochromic compound. The reverse photochromic compound is one in which the initial state (ring-opened body) is colored and becomes colored (ring-closed body) by light irradiation.
Furthermore, Non-Patent Document 1 reports a sulfone-type diarylethene-based photochromic compound in which the binding position of the ethene moiety and the aryl moiety is 3-position (FIG. 16 (B2) of Non-Patent Document 1). . In this compound, a ring-opened body and a ring-closed body are reversibly changed.

However, an optical recording medium using photochromism has a problem of destruction of information due to light irradiation other than recording light such as reproduction light because of the high photoreversible reactivity of the photochromic compound.
In order to solve such problems, the present inventors have found a photochromic compound that changes irreversibly from a closed ring to a condensed ring by an elimination reaction induced by a photoreaction (Patent Document 3). Since a reaction in which a condensed ring that has been changed from a closed ring by the elimination reaction returns to the closed ring does not normally occur, the condensed ring obtained by the elimination reaction is excellent in stability. Because of these properties, the photochromic compound described in Patent Document 3 is useful as an optical recording molecular material for an optical recording medium having excellent record retention and durability.

JP 2006-134365 A JP 2009-062344 JP JP 2010-064968

Kim et al., Chem. Comm., 2005, p. 2503

  However, the photochromic compound described in Patent Document 3 is accompanied by volume shrinkage because the substance is released from the ring-closed body by the elimination reaction and is changed to a condensed ring. When using a photochromic compound as an optical recording molecular material, it is conceivable to form an optical recording medium by dispersing the photochromic compound in an appropriate binder resin material. Therefore, when an optical recording medium is formed using the photochromic compound described in Patent Document 3, there is a possibility that the optical recording medium may be distorted and distorted due to volume shrinkage every time information is recorded.

  The problem to be solved by the present invention is a photochromic compound that is excellent in record retention and durability, and is useful as a high-sensitivity optical recording medium that does not undergo volume change during information recording, and a write-once optical recording molecular material using the same It is to provide a display material and a fluorescent label material.

（上記した骨格構造（１）において、Ｘは、水素、ハロゲン、シアノ基、−ＣＨ_３や−Ｃ_２Ｈ_５等の炭素数１〜５の直鎖もしくは分岐型アルキル基、−ＯＣＨ_３や−ＯＣＨ_２ＣＨ_５等の炭素数１〜５のアルコキシ基、又はＣＨ_３ＣＯＯ−から成るグループの中から選択される置換基、Ｚは五員環（環上に炭素以外の原子を含んでも良い）の脂環式化合物、又は複素芳香族五員環、Ｒ_１、Ｒ_２はそれぞれ独立して水素原子、炭素数１〜３のアルキル基もしくはアルコキシ基、ハロゲン元素、シアノ基、又はホルミル基を表す。また、Ｐｈはフェニル基を表す。） The present inventor has developed a compound that can be developed into a write-once optical recording material by focusing on a hexatriene skeleton photochromic molecule that exhibits a high photochromic reaction even in a solid state and whose ring-closing state is thermally stable. It has been found that the photochromic compounds having the structures (1) and (1 ′) have various characteristics.

(In the above skeleton structure (1), X represents hydrogen, halogen, cyano group, a linear or branched alkyl group having 1 to 5 carbon atoms such as —CH ₃ or —C ₂ H ₅ , —OCH ₃ or — A substituent selected from the group consisting of an alkoxy group having 1 to 5 carbon atoms such as OCH ₂ CH ₅ or a group consisting of CH ₃ COO—, Z is a five-membered ring (which may contain atoms other than carbon on the ring); Or a heteroaromatic five-membered ring, R ₁ and R ₂ each independently represents a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, a halogen element, a cyano group, or a formyl group. In addition, Ph represents a phenyl group.)

を有するジアリールエテン化合物が知られているが、骨格構造（１）と（２）の比較から明らかなように、本発明のフォトクロミック化合物は、アリール基がスルホン化されているという特徴を有する。このような特徴的な構造は、本発明者が様々な構造のジアリールエテン化合物に関し、その分子構造と開環量子収率及び閉環量子収率との関係を調べた結果、スルホン化により開環量子収率が低下する傾向があることを見出した知見に基づき得られたものである。従って、本発明に係るフォトクロミック化合物は、閉環量子収率に比べて開環量子収率が非常に低いという特徴を有し、光照射によりいったん開環体（１）から閉環体（１’）に変化すると、開環体（１）にはほとんど戻らない。 One of the photochromic materials known so far is the following skeletal structure (2)

Although the diarylethene compound which has this is known, the photochromic compound of the present invention has a feature that the aryl group is sulfonated, as is clear from the comparison between the skeleton structures (1) and (2). Such a characteristic structure is the result of the present inventors examining the relationship between the molecular structure and the ring-opening quantum yield and the ring-closing quantum yield of diarylethene compounds having various structures. It was obtained based on the finding that the rate tends to decrease. Therefore, the photochromic compound according to the present invention has a feature that the ring-opening quantum yield is very low as compared with the ring-closing quantum yield, and is once changed from the ring-opened body (1) to the closed ring body (1 ′) by light irradiation. When changed, it hardly returns to the ring-opened product (1).

In the photochromic compound of the present invention having the skeleton structures (1) and (1 ′), by selecting a specific structure as X, Z, R ₁ , R ₂ , the photochromic compound of the present invention can be irradiated by light irradiation. It changes from an open ring to a closed ring, and the change is irreversible. When a write-once optical recording molecular material, display material, or the like is configured using such a photochromic compound, the light that changes from the ring-opened body (1) to the ring-closed body (1 ′) is used as recording light, and the fluorescence of this ring-closed body The wavelength of the excitation light that gives the wavelength is the reproduction light.
Here, irreversibly changing from a ring-opened body to a ring-closed body means that only a change from the ring-opened body to the ring-closed body occurs and the ring-closed body does not change to the ring-opened body. Note that the case of irreversibly changing from a ring-opened body to a ring-closed body means a case where the ring-opening quantum yield of the photochromic compound is not measurable or 1 × 10 ⁻⁴ or less.

In the photochromic compound of the present invention having the skeleton structures (1) and (1 ′), the absorption spectrum in the closed state is preferably displaced by 100 nm or more in terms of wavelength from the absorption spectrum in the ring-opened state. It is preferable to be displaced to the long wavelength side. Mutual influences such as interference between the recording light and the reproduction light can be suppressed by the shift (shift) of the spectrum.
That is, the wavelength of the recording light, which is light for changing the ring-opened state represented by the general formula (1) to the ring-closed state represented by the general formula (1 ′), and the general formula (1 ′) It is preferable that the wavelength of excitation light, that is, light that gives fluorescence emission in a closed state, that is, the wavelength of the reproduction light is at least 100 nm or more. Furthermore, it is preferable that the reproduction light is displaced (shifted) to the longer wavelength side than the recording light.

式（３）及び式（４）で表されるフォトクロミック化合物は、いずれも開環量子収率（閉環状態から開環状態への光反応量子収率）が 1×10^-5 以下であり、開環体から閉環体に非可逆で変化する。 A preferred example of the photochromic compound of the present invention comprises a diarylethene structure represented by the following formula (3) or formula (4).

The photochromic compounds represented by formula (3) and formula (4) both have a ring-opening quantum yield (photoreaction quantum yield from a ring-closing state to a ring-opening state) of 1 × 10 ⁻⁵ or less, It changes irreversibly from a ring to a closed ring.

  In the photochromic compound of the present invention described above, a single molecule changes from a ring-opened state to a ring-closed state having a different absorption spectrum by light irradiation, and it is very difficult to return from the ring-closed state to the ring-opened state. It is useful as a material for recording media.

  Further, if the above-described photochromic compound of the present invention is dispersed in a material such as a resin and molded into an appropriate shape, it can be used as a display member for a nameplate or an advertisement. This display member can write display information such as characters and designs desired to be displayed with recording light, and then can display the written characters and designs by irradiating with reproduction light. Since it is possible to display characters or the like that emit light from the inside of the display member, it is possible to realize a display that has excellent aesthetics and attracts attention. Furthermore, display information can be added and written many times. In addition, for example, when a person approaches, it is also possible to display characters, symbols, etc. by irradiating with reproduction light as necessary, making the display stand out more than when irradiating with reproduction light at all times. The maintenance cost can be reduced.

  The display member formed using the photochromic compound of the present invention has characteristics that data can be added and recorded data is invisible without reproducing light. By utilizing such characteristics, for example, the following useful label material can be provided. That is, if the product offered to the market is distributed with the label material containing the photochromic compound of the present invention, information can be recorded at each stage from production to consumption or disposal. It is possible to improve traceability (traceability) of the distribution channel. Such a label material can be used for quality control and the like because information can be recorded not only at each stage from production to consumption / disposal of products but also at each stage such as a manufacturing process in a factory. . Moreover, since the recorded information can be visually recognized only by the irradiation of the reproduction light, the recorded information can be kept secret.

  Further, the photochromic compound of the present invention has a light-stimulated fluorescence property that forms a new absorption band in the visible region with ultraviolet light irradiation, and emits fluorescence when the absorption band is photoexcited by recording light. In recent years, fluorescent proteins whose fluorescence characteristics can be switched between an ON state and an OFF state in accordance with light stimulation have attracted attention as biological observation pigments such as biolabels (Miyawaki et al. WO2005 / 113772). By utilizing such photostimulated fluorescence, it is possible to dramatically improve the resolution of a conventional fluorescence microscope (Science 2006, 313 ° 1642-1645). Since the photochromic compound produced in the present invention is also turned on by light stimulation, it can be applied as a similar fluorescent label dye for ultra-high resolution observation.

  The photochromic compound of the present invention undergoes a photochromic reaction upon irradiation with light, and changes from a ring-opened body to a ring-closed body whose absorption spectrum is displaced. Since the photochromic compound of the present invention has a very low ring-opening quantum yield compared to the ring-closed quantum yield, the ring-closed compound is excellent in stability. For this reason, there is almost no return to the ring-opened body by irradiation of recording light or reproduction light.

Because of these properties, the photochromic compound of the present invention is useful as various optical functional materials, and in particular, since recorded information is not lost, high sensitivity excellent in record retention and durability. It is useful as an optical recording molecular material.
In particular, by adopting a condensed ring that emits fluorescence when irradiated with reproduction light, three-dimensional optical recording, near-field optical recording, and holographic optical recording are possible.

The figure which shows the chemical structure of the several Example of the photochromic compound of this invention. The figure which shows a part of synthetic route of the photochromic compound A1. The figure which shows a part of synthetic route of the photochromic compound A2. The figure which shows a part of synthetic route of the photochromic compound A3. The figure which shows the change of the absorption spectrum of the photochromic compound A1. The figure which shows the emission spectrum of the ring-closure body of photochromic compound A1. The figure which shows the example of a photochromic reaction when using the photochromic compound A1 as a write-once type optical recording molecular material. The figure which shows the change of the absorption spectrum of the photochromic compound A2. The figure which shows the absorption spectrum of the ring-closure body of photochromic compound A2. The figure which shows the change of the absorption spectrum of the photochromic compound A3. The figure which shows the emission spectrum of the ring-closure body of photochromic compound A3. The table | surface which shows the photochromic characteristic of the photochromic compound which concerns on an Example. The figure which shows the structure of the write-once type optical recording device using a photochromic compound. The figure for demonstrating that the ring-closing quantum yield of the photochromic compound of this invention is very high, and a ring-opening quantum yield is low compared with a ring-closing quantum yield. The figure which shows the structure of the photochromic compound of a comparative example.

FIG. 1 shows specific examples of the photochromic compound of the present invention by chemical formulas (A1) to (A5). In FIG. 1, Me represents a methyl group, but Me is partially omitted in the following drawings.
Any of the photochromic compounds represented by the chemical formulas (A1) to (A5) (hereinafter referred to as photochromic compounds A1 to A5) changes to a ring-closed body by irradiation with ultraviolet light.

1. Synthesis Method Photochromic compounds A1 to A5 can be synthesized by various methods. Below, the example of the synthesis | combining method of compound A1-A3 is shown.
(1) Synthesis of photochromic compound A1 <TaTO4-Ph3> (Figure 2)
In a brown eggplant flask, add 4,5-Bis (2,4-dimethyl-5-phenylthiophen-3-yl) -2-phenylthiazole 42 mg (78 μmol, 1.0 eq.) In 8 ml of CH ₂ Cl ₂ and stir. Then, 0.116 g (0.470 mmol, 6.0 eq.) Of 70% m-Chloroperbenzoic acid (m-CPBA) (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) was added and stirred at room temperature for 25 hours. Subsequently, the reaction solution was quenched with water and extracted with CH ₂ Cl ₂ to give a pale yellow solid. Roughly divided by column chromatography [Hexane / EtOAc (4: 1) and then EtOAc] in the dark, about 80% was isolated and purified by normal phase HPLC [Hexane / EtOAc (75:25)] x 7 times. The purified product was identified by 1H NMR (300 MHz; CDCl ₃ ), DART-MS. The yield of the desired product was 36 mg, and the yield was 76%.

(2) Synthesis of photochromic compound A2 <BDMTFO4-Ph> (Figure 3)
In a brown eggplant flask, 1,2-Bis (2,4-dimethyl-5-phenylthiophen-3-yl) 3,3,4,4,5,5-hexafluorocyclopentene (manufactured by TCI) 49.55 mg (90.32 μmol, 1.0 eq) .) And dissolved in 10 ml of CH ₂ Cl ₂ , add 0.135 g (0.547 mmol, 6.05 eq.) Of 70% m-Chloroperbenzoic acid (m-CPBA) (manufactured by TCI) with stirring, and stir at room temperature for about 2 days did. Subsequently, the reaction solution was quenched with water and extracted with CH ₂ Cl ₂ to give a pale yellow solid. It was separated into two components by column chromatography [Hexane / EtOAc (4: 1)] (in the dark) and purified by HPLC [Hexane / EtOAc (90:10)]. As a result of FAB-MS measurement of the obtained two components, it was found that they were a dioxide form (580) and a tetraoxide form (612). The dioxide was a red solid and the tetraoxide was a yellow luminescent solid.

(3) Synthesis of photochromic compound A3 <BDMTFO4-TerPh> (Figure 4)
In a brown eggplant flask, add 1,2-Bis [2,4-dimethy-5- (2,4-diphenylphenyl) thiophen-3-yl] perfluorocyclopentene 50.96 mg (59.74 μmol, 1.0 eq.) And CH ₂ Cl ₂ After dissolving in 2 ml, 0.151 g (0.613 mmol, 10.02 eq.) Of 70% m-Chloroperbenzoic acid (m-CPBA) (manufactured by TCI) was added with stirring, and the mixture was stirred at room temperature for about 4 days. The raw material disappeared with TCL, and the formation of a dioxide (red) and tetraoxide (yellow) was confirmed. The reaction solution was quenched with water and extracted with CH ₂ Cl ₂ to give yellow crude 0.111 g. This was roughly separated by column chromatography [from Hexane / EtOAc (4: 1) to graded] and purified by normal phase HPLC [Hexane / EtOAc (4: 1)].

2. Photochromic characteristics The results of examining various photochromic characteristics of the above-described photochromic compounds A1 to A3 are shown below.

(1) Photochromic characteristics of photochromic compound A1 FIG. 5 shows the change in absorption spectrum associated with the change of the photochromic compound A1 from a ring-opened body to a ring-closed body in a 2M-THF solution. Specifically, it shows the change in absorption spectrum every 30 seconds when the ring-opened compound A1 is continuously irradiated with ultraviolet light of 313 nm, the broken line 5a shows the absorption spectrum of the ring-opened substance, and the thick solid line 5b Indicates the absorption spectrum of a closed ring. The other thin solid line shows the absorption spectrum in the process in which compound A1 changes from an open ring to a closed ring. FIG. 5 shows that Compound A1 changes from a ring-opened body to a ring-closed body by continuing to irradiate 313 nm ultraviolet light for 360 seconds (30 seconds × 12). In addition, it can be seen that the absorption spectrum of the photochromic compound A1 is changed by 100 nm or more on the long wavelength side by changing from an open ring to a closed ring.

  FIG. 6 shows the emission spectrum of the ring-closed product of photochromic compound A1. From FIG. 5 and FIG. 6, the photochromic compound A1 changes from an open ring to a closed ring by irradiation with ultraviolet light having a wavelength of 300 to 400 nm, and excites the closed ring with blue-green light having a wavelength of about 490 nm. It turns out to emit orange light.

Therefore, when compound A1 is used for a write-once optical recording molecular material, ultraviolet light having a wavelength of 300 nm to 400 nm is used as recording / writing light, blue-green light having a wavelength of 490 nm is used as recording / reading light, and light having a wavelength of 576 nm is used as detection light. be able to. In addition, since the ring-opened body does not absorb light having a wavelength of 490 nm, the ring-opened body does not change to a closed ring even when irradiated with recording readout light, and is useful as a write-once type optical recording molecular material. That is, the compound A1 as a write-once type optical recording material molecule has a superior spectral shift after photoreaction and can easily suppress crosstalk between the recording / writing light and the recording / reading light.
As a result of continuing the fluorescence observation by irradiating the cyclized compound A1 with light at 436 nm for 12 hours, the decrease rate of the fluorescence intensity was 1% or less. This indicates that the ring-opening reaction in which the ring-closed body returns to the ring-opened body does not proceed under irradiation with light of 436 nm, and it can be seen that it can be used as a write-once type optical recording material.
FIG. 7 shows a photochromic reaction when the photochromic compound A1 is used as a write-once optical recording molecular material.

(2) Photochromic compound A2
FIG. 8 shows the change in the absorption spectrum of the photochromic compound A2 in 2M-THF accompanying the change from the ring-opened form to the ring-closed form. Specifically, it shows the change in absorption spectrum every 9 minutes when the ring-opened compound A2 is continuously irradiated with ultraviolet light of 313 nm, the broken line 8a shows the absorption spectrum of the ring-opened substance, and the thick solid line 8b Indicates the absorption spectrum of a closed ring. The other thin solid line shows the absorption spectrum in the process in which compound A2 changes from an open ring to a closed ring. FIG. 8 shows that Compound A2 changes from a ring-opened body to a ring-closed body by continuing to irradiate ultraviolet light at 313 nm for 81 minutes (9 minutes × 9).

  Further, it can be seen that, similarly to the photochromic compound A1, the absorption spectrum of the compound A2 also changes by about 100 nm on the long wavelength side by changing from the ring-opened body to the ring-closed body. The photochromic compound A2 changes from an open ring to a closed ring by irradiation with ultraviolet light having a wavelength of 280 to 300 nm, and emits green light (wavelength 550 nm) by exciting the closed ring with blue-violet light (wavelength 423 nm). In addition, since the ring-opened body does not absorb blue-violet light (wavelength 423 nm), the photochromic compound A2 is also useful as a write-once optical recording molecular material.

FIG. 9 shows the change in absorption spectrum when the ring-closed compound A2 is irradiated with 436 nm light for 46 hours and then irradiated with 313 nm ultraviolet light. In FIG. 9, the solid line 9a shows the absorption spectrum before irradiating the closed ring of compound A2 with light, and the broken line 9b shows the absorption spectrum when 436 nm light is continuously applied for 46 hours. A solid line 9c shows an absorption spectrum in the case where irradiation with 436 nm light is continued for 46 hours and then irradiation with 313 nm ultraviolet light for 80 minutes.
From FIG. 9, it can be seen that approximately 90% of the closed ring remains even after 46 hours of light irradiation of the closed ring of compound A2. Further, as a result of irradiating with 313 nm ultraviolet light for 80 minutes following irradiation with 436 nm light, it can be seen that the absorption spectrum of the closed ring is almost recovered. From this, compound A2 undergoes a photo-ring-opening reaction upon irradiation with 436 nm light, and proceeds with a photo-ring-closing reaction upon irradiation with ultraviolet light at 313 nm. Since the rate of progress of the photo-ring opening reaction is very slow compared to the rate of progress of the photo-ring closure reaction, it can be seen that the photo-ring-opening reaction of Compound A2 is sufficiently suppressed.

For example, an existing music CD (700MB = 8 x 7 x 10 ⁸ bits, 74 minutes = 4440 seconds) requires approximately 80 x ^10-8 seconds (= 4440 seconds ÷ (56 x 10 ⁸ bits)) for 1-bit playback. Will do. From the experimental results shown in FIG. 9, it can be said that Compound A2 is a compound capable of optical recording and reproduction for 46 hours because 90% of the ring-closure remains even after light irradiation for 46 hours. Therefore, a virtual optical disk using Compound A2 capable of optical recording / reproducing for 46 hours per bit can record / reproduce approximately 2 × 10 ¹¹ times (= 46 × 3600 seconds ÷ (80 × 10 ⁻⁸ seconds)). It is expected. This corresponds to the fact that a 74-minute music disc is played back for about 30 million years, and such a virtual music disc has almost no practical limit on the number of reproducible recordings. Note that the compound A1 described above has information retention performance and nondestructive recording / reproduction capability that exceed these.

(3) Photochromic compound A3
FIG. 10 shows the change in the absorption spectrum of the photochromic compound A3 in 2M-THF accompanying the change from the ring-opened form to the ring-closed form. Specifically, the change in the absorption spectrum every 5 seconds when the ring-opened compound A3 is continuously irradiated with ultraviolet light of 340 nm shows the absorption spectrum of the ring-opened product and the thick solid line 10b. Indicates the absorption spectrum of a closed ring. The other thin solid line shows the absorption spectrum in the process in which compound A3 changes from an open ring to a closed ring. From FIG. 10, it can be seen that Compound A3 changes from a ring-opened product to a ring-closed product by continuing to irradiate UV light of 340 nm for 5 seconds. FIG. 11 shows the emission spectrum of the closed ring of photochromic compound A3. Similar to the photochromic compound A1, it can be seen that the absorption spectrum of the compound A3 is changed to 100 nm or more on the long wavelength side by changing from the ring-opened form to the closed-form. Photochromic compound A3 changes from an open ring to a closed ring by irradiation with ultraviolet light having a wavelength of 300 to 350 nm, and emits green light having a wavelength of 550 to 560 nm by exciting the closed ring with blue-violet light near a wavelength of 445 nm. I understand that.

  Therefore, when compound A3 is used as a write-once optical recording molecular material, ultraviolet light having a wavelength of 300 to 350 nm is used as recording / writing light, blue-violet light having a wavelength of 445 nm is used as recording / reading light, and green light having a wavelength of 550 to 560 nm is used as detection light. Light can be used. Moreover, since the ring-opened body does not absorb blue-violet light having a wavelength of 445 nm, the photochromic compound A3 is also useful as a write-once optical recording molecular material.

FIG. 12 summarizes the molar absorption coefficient, emission quantum yield, and reaction quantum yield of the ring-closed and ring-opened photochromic compounds A1 to A3. In FIG. 12, the emission quantum yield of the ring-closed product and the emission quantum yield of the ring-opened product are the ratio (yield) of change from the ring-opened product to the ring-opened product by light irradiation, and change from the ring-opened product to the ring-closed product. It means a ratio (yield), and is synonymous with a ring-opening reaction quantum yield and a ring-closing reaction quantum yield.
In FIG. 12, the “photoreaction quantum yield” is “not measurable” is 1 × 10 ⁻⁵ or less, and the emission wavelength and quantum yield of the colored product is “−”. Indicates that no luminescence is observed. “Unmeasured” indicates that the light emission characteristics of the compound have not been measured yet.

As is clear from FIG. 12, the photoreaction quantum yield (ring-opening quantum yield) of the ring-closed product of any photochromic compound A1 to A3 is more than the photoreaction quantum yield (ring-closed quantum yield) of the ring-opened product. It is also very low and 2 × 10 ⁻⁵ or less, and it can be seen that irreversibly changes from the open ring to the closed ring.
In addition, since compound A1 and A3 have a high emission quantum yield of ring-closed compounds, they can detect detection light (light emission when ring-closed bodies are excited) with high sensitivity when used as write-once optical recording molecular materials. it can.

3. Other Properties The photochromic compounds A1 and A3 are amorphous, and a thin film can be formed without being dispersed in the binder resin material. Due to such properties, the photochromic compounds A1 and A3 can produce a write-once optical recording device independently without adding other materials. On the other hand, as shown in FIG. 13, the photochromic compounds A2, A4, and A5 are dispersed in the binder resin material 1 to form an optical recording molecular material 10, which is formed into a thin film to form a write-once type optical recording device. Can be manufactured.
The reason why only the photochromic compounds A1 and A3 are amorphous molecules is thought to be because these compounds have more benzene rings than the photochromic compounds A2 and A4, but the details are unknown.

All the photochromic compounds according to the present invention have a very high ring closure quantum yield. The reason will be described with reference to FIG. FIG. 14 shows the structure before sulfonation of photochromic compound A4 (the structure of Comparative Example B5 described later), but the high ring closure quantum yield does not change before and after sulfonation.
As shown in FIG. 14, in the molecular structure in the ring-opened state of the photochromic compound obtained from the X-ray structural analysis results, the interatomic distances indicated by broken lines P1 and P2 are 2.95 mm and 2.69 mm, respectively, and van der Waals. It can be seen that suction interaction is working, which is shorter than the radius. This interaction serves to immobilize the ring-opened conformation in a structure suitable for photochromic reactions. As a result, the interatomic distance indicated by the broken line P3 is about 3.5 mm, which is very short (this is about the same as the distance between graphite planes of 3.45 mm). For this reason, it seems that it is easy to change from a ring-opening state to a ring-closing state.

Comparative example

  For comparison with the photochromic compounds A1 to A5 according to the above-described examples, the molecular structure of the already known photochromic compound is shown in FIG. 15 together with the ring opening quantum yield and the ring closure quantum yield. Both comparative examples have already been reported in non-patent literature such as academic papers. Therefore, in order to distinguish the compounds B5 and B6 from which the inventor actually measured the ring-opening quantum yield and the ring-closing quantum yield, the ring-opening quantum yield and the ring-closing quantum yield cited from the non-patent literature are Shown with the name of the non-patent literature. Note that, in the molecular structure shown in FIG. 15, a portion indicated by a simple line indicates that a methyl group (Me) is bonded.

  In FIG. 15, the photochromic compound of the comparative example shown by the formula (B2) is obtained by sulfonating the photochromic compound of the comparative example shown by the formula (B1). As is apparent from the ring-opening quantum yields of these comparative examples, the ring-opening quantum yield is greatly reduced by sulfonation. On the other hand, the ring closure quantum yield also decreased due to sulfonation, but the decrease rate is small compared to the ring opening quantum yield.

When the photochromic compound of the comparative example represented by the formula (B3) is sulfonated, the photochromic compound A1 of the example is obtained. The photochromic compound B3 has a ring-opening quantum yield of 0.07, while the photochromic compound A1 of the example has a ring-opening quantum yield of 1 × 10 ⁻⁵ or less. Therefore, also in this case, the ring-opening quantum yield was greatly reduced by sulfonation.

When the photochromic compound of the comparative example represented by the formula (B4) is sulfonated, the photochromic compound A2 of the example is obtained. The photochromic compound B4 has a ring-opening quantum yield of 0.015, while the photochromic compound A2 of the example has a ring-opening quantum yield of 2 × 10 ⁻⁵ or less. Therefore, also in this case, the ring-opening quantum yield was greatly reduced by sulfonation.

  When the photochromic compound of the comparative example represented by the formula (B5) is sulfonated, the photochromic compound A4 of the example is obtained, and when the photochromic compound of the comparative example represented by the formula (B6) is sulfonated, the photochromic compound A5 of the example is obtained. The photochromic compounds A4 and A5 of these examples also have unmeasured ring-opening quantum yields, but the ring-opening quantum yields of Comparative Examples B5 and B6 are 0.008 and 0.007, and the ring-opening quantum yield by sulfonation is From the decrease, it was expected that the ring-opening quantum yields of the photochromic compounds A4 and A5 of the examples also showed very small values.

DESCRIPTION OF SYMBOLS 1 ... Binder resin material 10 ... Optical recording molecular material

Claims (9)

The photochromic compound represented by following General formula (1).

(In the above skeleton structure (1), X is hydrogen, halogen, cyano group, linear or branched alkyl group having 1 to 5 carbon atoms, alkoxy group having 1 to 5 carbon atoms, or CH ₃ COO— A substituent selected from the group consisting of: Z is a five-membered ring (which may contain atoms other than carbon on the ring), or a heteroaromatic five-membered ring, R ₁ and R ₂ are Each independently represents a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, a halogen element, a cyano group, or a formyl group, and Ph represents a phenyl group.)   2. The photochromic compound according to claim 1, wherein, in the general formula (1), Z is selected from a heteroaromatic five-membered ring composed of indole, azaindole, thiazole, and benzothiophene. By irradiating light of a predetermined wavelength, the following general formula (1 ′)

The photochromic compound according to claim 1, wherein the photochromic compound is irreversibly changed to a closed ring represented by formula (1). The photoreaction quantum yield is 1 × 10 ⁻⁴ or less with respect to the change from the ring-closed state represented by the general formula (1 ′) to the ring-opened state represented by the general formula (1). 3. The photochromic compound according to 3.   The ring-absorption state absorption spectrum represented by the general formula (1 ') is displaced to a longer wavelength side than the ring-opening state absorption spectrum represented by the general formula (1). Or the photochromic compound of 4.   The wavelength of light that changes the ring-opened state represented by the general formula (1) to the ring-closed state represented by the general formula (1 ′) and fluorescence emission to the ring-closed state represented by the general formula (1 ′) The photochromic compound according to any one of claims 3 to 5, wherein the wavelength of light to be applied is at least 100 nm or more. A recordable optical recording molecular material used as a recording material of a recordable optical recording medium in which information is recorded by irradiation of recording light and the information is reproduced by irradiation of reproduction light,
Ring-opened or closed ring (1 ′) represented by the following general formula (1)

(In the above skeletal structures (1) and (1 ′), X is hydrogen, halogen, a cyano group, a linear or branched alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, Or a substituent selected from the group consisting of CH ₃ COO—, Z is a five-membered ring (which may contain atoms other than carbon on the ring), or a heteroaromatic five-membered ring, R ₁ and R ₂ each independently represents a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, a halogen element, a cyano group, or a formyl group, and Ph represents a phenyl group.
And a photochromic compound that changes irreversibly from the ring-opened body (1) to the ring-closed body (1 ′) by irradiation of the recording light and emits light from the ring-closed body (1 ′) by irradiation of the reproduction light. A write-once optical recording molecular material comprising: Information is recorded by irradiation of recording light, and the information is reproduced by irradiation of reproduction light,
Ring-opened or closed ring (1 ′) represented by the following general formula (1)

(In the above skeletal structures (1) and (1 ′), X is hydrogen, halogen, a cyano group, a linear or branched alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, Or a substituent selected from the group consisting of CH ₃ COO—, Z is a five-membered ring (which may contain atoms other than carbon on the ring), or a heteroaromatic five-membered ring, R ₁ and R ₂ each independently represents a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, a halogen element, a cyano group, or a formyl group, and Ph represents a phenyl group.
And a photochromic compound that changes irreversibly from the ring-opened body (1) to the ring-closed body (1 ′) by irradiation of the recording light and emits light from the ring-closed body (1 ′) by irradiation of the reproduction light. And a display material including a resin material. A fluorescent label material in which information is recorded by irradiation of recording light and the information is reproduced by irradiation of reproduction light,
Ring-opened or closed ring (1 ′) represented by the following general formula (1)

(In the above skeletal structures (1) and (1 ′), X is hydrogen, halogen, a cyano group, a linear or branched alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, Or a substituent selected from the group consisting of CH ₃ COO—, Z is a five-membered ring (which may contain atoms other than carbon on the ring), or a heteroaromatic five-membered ring, R ₁ and R ₂ each independently represents a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, a halogen element, a cyano group, or a formyl group, and Ph represents a phenyl group.
And a photochromic compound that changes irreversibly from the ring-opened body (1) to the ring-closed body (1 ′) by irradiation of the recording light and emits light from the ring-closed body (1 ′) by irradiation of the reproduction light. A fluorescent label material comprising:

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