JP2002294094A - Cyanine pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic pigment compound which absorbs visible light, and to provide its use. SOLUTION: A cyanine pigment of general formula 1 (R1 and R2 are mutually same or different aliphatic hydrocarbon groups which may have substituents, respectively; R3 and R4 are each a suitable substituent; Z1 and Z2 are each a cyclic group for completing an indole structure; the cyclic group may have one or more substituents) in which mutually same or different indole structure- having cyclic groups are bound to both the ends of a trimethine chain having a squalirium structure. A light absorbent containing the cyanine pigment. A method for producing the cyanine pigment via a process for reacting an indole compound with a squaric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a novel cyanine dye, and more particularly to a cyanine dye having a squarylium structure in a molecule useful as a light absorber.

[0002]

2. Description of the Related Art Living organisms are exposed to various lights including natural light. Natural light consists of light in the ultraviolet, visible, and infrared regions, and is an essential element for many organisms to survive, but when it comes to the light in individual regions, some are useful for living things. If there are, some are not. For example, light in the ultraviolet and visible regions is an essential component of photosynthesis in plants and vitamin D in animals, but too much light can cause skin cell death and, in some cases, damage DNA. , Leading to skin cancer. On the other hand, light in the infrared region has the effect of warming living organisms, but if exposed too much, it may cause burns, such as light in the near infrared region,
Some exacerbate cataracts. In addition, in certain immune diseases and viral diseases, natural light may directly or indirectly cause the disease to develop or the symptoms to worsen. Such a problem associated with exposure is included not only in natural light but also in ambient light including artificial light in general. Remarkable advances in modern science have revealed various obstacles and inconveniences associated with exposure, along with the useful effects of light in living organisms. Thus, various types of light shielding means have been conventionally proposed in various fields.

Light-shielding means can be broadly classified into physical means for blocking light by an object and chemical means for blocking light by absorbing it with a light absorbing agent. Looking at chemical means using an organic dye compound as a light absorber, for example, in the field of clothing,
As disclosed in JP-A-018 and JP-A-9-255890, an organic dye compound having an ultraviolet absorbing ability such as a benzotriazole derivative or a benzophenone derivative is kneaded into a fiber to impart ultraviolet blocking ability to clothing. And a method of imparting infrared blocking ability to clothing by dyeing fibers with an organic dye compound having infrared absorbing ability such as an aminium derivative. However, among these methods, when the former method is used, there is a problem that, although light in the ultraviolet region can be blocked, light in other regions cannot be blocked at all. On the other hand, the latter method cannot block light outside the infrared region at all, and the light absorbing agent itself develops a color.
Depending on the clothing, it was difficult to adjust the desired color, color tone and texture.

In recent years, as obstacles caused by natural light and artificial light have become known, not only in the field of clothing, but also in various other fields, there is a demand in a wide range of light from the ultraviolet region to the infrared region. There has been a need for a light absorber that can efficiently block light in a region. As a method for solving the above-mentioned difficulties in the prior art and responding well to the demands of the times, Japanese Patent Application Laid-Open
In JP-A-328039, there are disclosed a chalcone structure, a base styryl structure, a cyanine structure, a merocyanine structure, a phenylmethane structure, a coumarin structure, a pyrilium structure and a nickel complex structure which absorb light in an ultraviolet region, a visible region and / or an infrared region. It has been proposed to use an organic dye compound having any one of them in an appropriate combination depending on the application. However, even when such organic dye compounds are used in combination, the types and the mixing ratios of the individual organic dye compounds to be combined still have to be determined one by one by trial and error according to the application. Absent. In such a situation, the types of the organic dye compounds specifically disclosed in JP-A-2000-328039, in particular, the types of the organic dye compounds that absorb visible light, cannot be said to be large enough to cope with a wide variety of uses. .

[0005]

In view of such circumstances, an object of the present invention is to provide an organic dye compound that absorbs visible light, in particular, a novel organic dye compound having a cyanine structure and its use. And

[0006]

Means for Solving the Problems The present inventors have conducted intensive research,
As a result of the search, a cyanine dye having an indole structure and having the same or different cyclic groups bonded to both ends of a trimethine chain having a squarylium structure was obtained.
Such a cyanine dye efficiently absorbs visible light in the yellow to red range and has high light fastness. Therefore, when used alone or in combination with another organic dye compound, light for blocking light in the visible region is used. It can be used advantageously as an absorbent. The present invention is based on the creation of a novel organic dye compound and the discovery of its industrially useful properties.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a cyanine dye comprising trimethine chains having a squarylium structure and the same or different cyclic groups having an indole structure bonded to both ends. The present invention relates to such cyanine dyes in general, but when used as a light absorber, those represented by the general formula 1 are preferred.

[0008]

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In the general formula 1, R ₁ and R ₂ represent the same or different aliphatic hydrocarbon groups, and these aliphatic hydrocarbon groups may have one or more substituents. Examples of individual aliphatic hydrocarbon groups include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert
-Pentyl, 1-methylpentyl, 2-methylpentyl, 2-pentenyl, 2-penten-4-ynyl, hexyl, isohexyl, 5-methylhexyl, pentyl, octyl, nonyl , Decyl, undecyl, dodecyl, octadecyl and the like.

One or more hydrogen atoms in such an aliphatic hydrocarbon group may be substituted without departing from the object of the present invention. As individual substituents, for example, methyl group, ethyl group, propyl group, butyl group, aliphatic hydrocarbon group such as pentyl group, cyclopropyl group,
Alicyclic hydrocarbon group such as cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-cyclohexenyl group, cycloheptyl group, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, xylyl group, mesityl group , O-
Cumenyl group, m-cumenyl group, p-cumenyl group, aromatic hydrocarbon group such as biphenylyl group, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group,
Ether groups such as benzyloxy group and phenoxy group, ester groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, acetoxy group and benzoyloxy group, and halogen groups such as fluoro group, chloro group, bromo group and iodo group. No.

Although depending on the type of the solvent, the cyanine dye of the present invention generally has a lower solubility in the solvent as the chain length of the aliphatic hydrocarbon group in R ₁ and R ₂ becomes shorter. For example, a cyanine dye in which both R ₁ and R ₂ have 1 carbon atom is insoluble in ether-based or ketone-based organic solvents such as tetrahydrofuran, ethyl methyl ketone, and cyclohexanone, as described below, and is therefore difficult to handle. And its use is limited. From the viewpoint of solubility alone, the upper limit of the chain length is not particularly limited, but if the chain length is too long, the cyanine dye may be difficult to crystallize or may be difficult to purify. Therefore, depending on the application, the chain length of the aliphatic hydrocarbon group in R ₁ and R ₂ is usually adjusted to have 2 or more carbon atoms, preferably 4 to 18 carbon atoms. The present invention relates to R ₁
And cyanine dyes in which both R ₂ are methyl groups are not excluded, but since such cyanine dyes have low solubility in solvents, depending on the application, either R ₁ or R ₂ is a methyl group. In some cases, the other is an aliphatic hydrocarbon group having 2 or more carbon atoms, and R ₁
And the sum of the carbon numbers in R ₂ and R ₂ is preferably greater than 2.

R ₃ and R ₄ in the general formula 1 represent the same or different substituents. Individual substituents include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, te
tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, aliphatic hydrocarbon group such as isohexyl group, cyclopropyl group,
Cyclobutyl group, cyclopentyl group, alicyclic hydrocarbon group such as cyclohexyl group, phenyl group, o-tolyl group,
m-tolyl group, p-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, aromatic hydrocarbon group such as biphenylyl group, methoxy group, ethoxy group, propoxy group, Butoxy group, pentyloxy group, benzyloxy group, ether group such as phenoxy group, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, acetoxy group, ester group such as benzoyloxy group, fluoro group, chloro group,
Examples include a halogen group such as a bromo group and an iodo group, and further include a carboxy group, a hydroxy group, a cyano group, and a nitro group.

Z ₁ and Z ₂ in the general formula 1 represent the same or different cyclic groups for completing the indole structure, and these cyclic groups may have one or more substituents. Examples of the individual cyclic group include a benzene ring,
Aromatic rings such as a naphthalene ring, a phenanthrene ring, a pyrene ring and a fluorene ring, and further, a heterocyclic ring such as a pyridine ring, a pyrazine ring, a quinoline ring, a quinoxaline ring, a carbazole ring, a dibenzofuran ring, and the like, are bonded to such a cyclic group. Examples of the substituent include, for example, an aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group and a pentyl group, and an aliphatic group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group and a cyclohexyl group. Cyclic hydrocarbon group, phenyl group, o-tolyl group, m
-Tolyl group, p-tolyl group, xylyl group, mesityl group,
o-cumenyl group, m-cumenyl group, p-cumenyl group, aromatic hydrocarbon group such as biphenylyl group, methoxy group, ethoxy group, propoxy group, butoxy group, tert-butoxy group, pentyloxy group, benzoyloxy group, Ether groups such as phenoxy groups, methoxycarbonyl groups, ethoxycarbonyl groups, propoxycarbonyl groups, acetoxy groups, ester groups such as benzoyloxy groups, fluoro groups, chloro groups, bromo groups, halogen groups such as iodine groups, and further, hydroxy Group, carboxy group, cyano group, nitro group and the like.

Specific examples of the cyanine dye according to the present invention include, for example, those represented by Chemical Formulas 1 to 26. These are all yellow to red,
In particular, the molecular extinction coefficient around the wavelength of 550 to 620 nm (hereinafter, the molecular extinction coefficient may be abbreviated as “ε”) is large, so that visible light in such a wavelength range is efficiently absorbed and light resistance is high. And its solubility in commonly used alcohol-based, ether-based, ketone-based and halogen-based organic solvents is large enough to be practically acceptable.

[0015]

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[0039]

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[0040]

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The cyanine dye of the present invention can be prepared by various methods, but if importance is placed on economy, a compound represented by the general formula 2 having R ₁ , R ₃ and Z ₁ corresponding to the general formula 1 And a compound represented by the general formula 3 having R ₂ , R ₄ and Z ₂ corresponding to the general formula 1, and a squaric acid (3,
4-dihydroxy-3-cyclobutene-1,2-dione, also referred to as "squaric acid". )) Is preferred.

[0042]

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[0043]

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That is, a solvent is appropriately placed in a reaction vessel, and an appropriate amount of squaric acid is added thereto.
Are added in an appropriate amount (usually about equimolar), and the mixture is reacted at ambient temperature or a temperature higher than ambient temperature, usually 60 to 120 ° C. with stirring by heating under reflux or the like.

Examples of the solvent include pentane, hexane, cyclohexane, octane, benzene, toluene,
Hydrocarbons such as xylene, carbon tetrachloride, chloroform, 1,2-dichloroethane, 1,2-dibromoethane, trichloroethylene, tetrachloroethylene, chlorobenzene, bromobenzene, halides such as α-dichlorobenzene, methanol, ethanol, 1- Propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, phenol, benzyl alcohol, cresol, diethylene glycol, triethylene Alcohols and phenols such as ethylene glycol and glycerin, diethyl ether, diisopropyl ether, TH
F, ethers such as tetrahydropyran, 1,4-dioxane, anisole, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, dicyclohexyl-18-crown-6, methyl carbitol, ethyl carbitol, acetic acid, acetic anhydride, and trichloroacetic acid , Trifluoroacetic acid, propionic anhydride, ethyl acetate, butyl carbonate, ethylene carbonate, propylene carbonate, formamide,
Acids and acid derivatives such as N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, hexamethylphosphoric triamide; nitriles such as acetonitrile, propionitrile, succinonitrile, benzonitrile And nitro compounds such as nitromethane and nitrobenzene, and sulfur-containing compounds such as dimethylsulfoxide and sulfolane. These may be used in an appropriate combination as required.

When a solvent is used, the efficiency of the reaction generally decreases as the amount of the solvent increases, and conversely, as the amount of the solvent decreases, it becomes difficult to heat and stir uniformly, or a side reaction easily occurs. Therefore, the amount of the solvent is desirably up to 100 times, usually 5 to 50 times, the weight of the whole starting compound. The reaction is completed within 50 hours, usually 0.5 to 20 hours, depending on the type of the starting compound and the reaction conditions. The progress of the reaction can be monitored by a general-purpose method such as thin-layer chromatography, gas chromatography, and high-performance liquid chromatography. Any of the cyanine dyes represented by Chemical Formulas 1 to 26 can be produced in a desired amount by this method. The compounds represented by the general formulas 2 and 3 can be obtained by a general-purpose method of reacting an indole with an alkyl halide, and when a commercially available product is available, it may be used. . In the preparation, a cyanine dye in which R ₁ and R ₂ and R ₃ and R ₄ in Formula 1 are the same as each other is a cyanine dye in which R ₁ and R ₂ and R ₃ and R ₄ are different from each other. Compared with dyes, they are easy to purify and have significantly higher yields.

Although the cyanine dye of the present invention thus obtained may be used as a reaction mixture,
Usually, prior to use, analogous compounds such as, for example, dissolution, extraction, separation, gradient, filtration, concentration, thin-layer chromatography, column chromatography, gas chromatography, high-performance liquid chromatography, distillation, sublimation, crystallization, etc. Is purified by a general-purpose method for purifying, and if necessary, these methods are appropriately combined and applied. Depending on the application, for example, when used as a light absorber, luminescent agent or sensitizer in the field of optics or optoelectronics such as optical filters, organic electroluminescence, photochemical polymerization, laser recording, etc., prior to use. For example,
It is desirable that the product be highly purified by a method such as distillation, crystallization and / or sublimation.

As described above, the cyanine dye according to the present invention comprises visible light in the yellow to red range, particularly, a wavelength of 550.
In addition to efficiently absorbing visible light in the vicinity of about 620 nm to 620 nm and having high light resistance, for example, JP-A-2000-32
According to the method described in No. 8039, UV light alone or according to the application, other organic dye compounds that absorb light in the visible or infrared region, for example, a support material of a natural or synthetic polymer, Microencapsulating agent, binder, monomer, oligomer, polyfunctional reagent, glue, adhesive, coloring agent, flame retardant, wrinkle remover, deodorant, water repellent, oil repellent, antistatic agent, conductive agent, water absorption Agents, moisture inhibitors, fragrances, antioxidants, insect repellents, fungicides, antibacterial agents, antiallergic agents, blood circulation promoters, surfactants, emulsion stabilizers and chelating agents
Or, together with a plurality, by dissolving or dissolving in a solvent, by mixing, applying, spraying, dipping, fixing, etc., to include in articles such as clothing articles, bedclothes articles, sanitary articles, optical filters, etc. By adjusting the light transmittance or light reflectance of the article to a desired wavelength or degree, the light transmitted or reflected through the article can be adjusted to a desired chromaticity, color,
There is a benefit that can be adjusted to color tone and hand.

Further, since the cyanine dye of the present invention absorbs visible light in the yellow to red range, it is useful as a light absorber or sensitizer in the field of optoelectronics such as photochemical polymerization and laser recording. Yes, and
Those emitting visible light can also be advantageously used as luminescent agents in organic electroluminescence and dye lasers.

Hereinafter, embodiments of the present invention will be described based on examples.

[0051]

Example 1 <Cyanine dye> An appropriate amount of dimethyl sulfoxide was placed in a reaction vessel, 25 g of 2-methylindole was added and dissolved. After stirring, 8.6 g of sodium amide was added under stirring so that the temperature of the solution did not exceed 60 ° C. And octyl iodide 5
After sequentially adding 5 g in this order, the mixture was reacted in the same manner with stirring for another 1 hour. Thereafter, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was separated and concentrated under reduced pressure to obtain 47 g of an indole compound oil represented by the chemical formula 27.

[0052]

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Next, an appropriate amount of a benzene / butanol mixed solution was placed in a reaction vessel, 30 g of the indole compound represented by the above-mentioned formula 27 and 7 g of squaric acid were added, and the mixture was reacted under heating and reflux for 2 hours. The reaction mixture was treated with methanol /
When recrystallized with an acetone mixed solution, 13.5 g of a bright green crystal of a cyanine dye represented by Chemical Formula 3 was obtained.

When a part of the crystal was taken and measured by a conventional method, the melting point of the cyanine dye of this example was 179 to 180 ° C.
Met. When the visible absorption spectrum of the methanol solution was measured, the absorption maximum (ε
= 1.67 × 10 ⁵ ) was observed. In addition, ¹ H-nuclear magnetic resonance spectrum (hereinafter, “ ¹ H-NMR”) of the cyanine dye of the present example in a chloroform-d solution was obtained by a conventional method.
Spectrum. " ) Was measured, the chemical shift δ (ppm, TMS) was 0.88 (6H, t), 1.2
5 to 1.50 (20H, m), 1.77 to 1.85
(4H, m), 3.32 (6H, s), 4.15 (4
H, t), 7.23 to 7.36 (8H, m) and 9.
A peak was observed at the position of 21 (2H, d).

[0055]

Example 2 Cyanine dye An indole compound represented by the chemical formula 28 was obtained by reacting in the same manner as in Example 1 except that butyl iodide was used instead of octyl iodide. Then, the reaction was carried out in the same manner as in Example 1 except that the indole compound represented by Chemical Formula 28 was used instead of the indole compound represented by Chemical Formula 27, and represented by Chemical Formula 2. A bright green crystal of a cyanine dye was obtained.

[0056]

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When a part of the crystal was taken and measured by a conventional method, the melting point of the cyanine dye of this example was 234 to 236 ° C.
Met. When the visible absorption spectrum of the methanol solution was measured, the absorption maximum (ε
= 1.65 × 10 ⁵ ) was observed. When the ¹ H-NMR spectrum of the cyanine dye of this example in a chloroform-d solution was measured by a conventional method, the chemical shift δ (ppm, TMS) was 1.00 (6H, t).
46 (4H, m), 1.82 (4H, m), 3.32
Peaks were observed at (6H, s), 4.16 (4H, t), 7.26 to 7.36 (8H, m), and 9.21 (2H, d).

[0058]

Example 3 Cyanine dye An indole compound represented by the chemical formula 29 was obtained by reacting in the same manner as in Example 1 except that octadecyl iodide was used instead of octyl iodide. Then, the reaction was carried out in the same manner as in Example 1 except that the thus obtained indole compound represented by Chemical Formula 29 was used instead of the indole compound represented by Chemical Formula 27, and represented by Chemical Formula 5 Green crystals of cyanine dye were obtained.

[0059]

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When a part of the crystal was taken and measured by a conventional method, the melting point of the cyanine dye of this example was 146 to 147 ° C.
Met. When the visible absorption spectrum of the methanol solution was measured, the absorption maximum (ε
= 1.66 x 10 ⁵ ) was observed. Further, when the ¹ H-NMR spectrum of the cyanine dye of this example in a chloroform-d solution was measured by a conventional method, the chemical shift δ (ppm, TMS) was 1.00 (6H, t).
46 (4H, m), 1.82 (4H, m), 3.32
Peaks were observed at (6H, s), 4.16 (4H, t), 7.26 to 7.36 (8H, m), and 9.21 (2H, d).

[0061]

Example 4 <Cyanine dye> 2 in place of octyl iodide
The reaction was carried out in the same manner as in Example 1 except for using -ethylbromohexane, to obtain an indole compound represented by the chemical formula 30. Next, the reaction was carried out in the same manner as in Example 1 except that the thus obtained indole compound represented by Chemical Formula 30 was used instead of the indole compound represented by Chemical Formula 27, and represented by Chemical Formula 4 Green crystals of cyanine dye were obtained.

[0062]

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When a part of the crystal was taken and measured by a conventional method, the melting point of the cyanine dye of this example was 194 to 196 ° C.
Met. When the visible absorption spectrum of the methanol solution was measured, the absorption maximum (ε
= 1.65 × 10 ⁵ ) was observed. When the ¹ H-NMR spectrum of the cyanine dye of this example in a chloroform-d solution was measured by a conventional method, the chemical shift δ (ppm, TMS) was 0.86 to 0.96 (12
H, m), 1.25 to 1.50 (16H, m), 1.
99 (4H, m), 3.31 (6H, s), 4.06
Peaks were observed at (4H, d), 7.22 to 7.36 (8H, m) and 9.21 (2H, d).

Although the reaction conditions and yields are slightly different depending on the structure of the cyanine dye, the cyanine dyes according to the present invention include Examples 1 to 26 including those represented by Chemical Formulas 1 to 26 other than the above. The desired amount can be obtained by the methods described in No. 4 or according to those methods.

[0065]

EXPERIMENTAL EXAMPLE <Solubility of Cyanine Dye> Three kinds of cyanine dyes represented by the chemical formulas 2, 3 and 5 and a cyanine dye represented by a chemical formula 31 prepared according to the method of Example 1 are as follows. According to a conventional method, solubility in tetrahydrofuran (THF), methyl cellosolve, ethyl cellosolve, chloroform, ethyl methyl ketone (EMK), isopropyl methyl ketone (IPMK) and cyclohexanone at 20 ° C. was examined. The results are as shown in Table 1.

[0066]

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[0067]

[Table 1]

The results in Table 1 show that R ₁ and R
_This indicates that the shorter the chain length of _2, the lower the solubility of the cyanine dye in the organic solvent. That is, the cyanine dye represented by the chemical formula 31 in which both R ₁ and R ₂ have a carbon number of 1 has the carbon number of 1, but dissolves in chloroform, but does not substantially dissolve in the other solvents tested and is insoluble. Met. On the other hand, the cyanine dye represented by Formula 2, 3, or 5 in which both R ₁ and R _{2 have} a chain length of 4 to 18 carbon atoms is represented by R ₁ and R 2
_As the chain length of No. ₂ became longer, the solubility in chloroform became higher (solubility 130 mg / 100 ml or more). Moreover, the cyanine dyes represented by Chemical Formulas 2, 3, and 5 are tetrahydrofuran (solubility: 10) in which the cyanine dyes represented by Chemical Formula 31 are not substantially dissolved.
mg / 100 ml or more), and the cyanine dyes represented by Chemical Formulas 2 and 3 were also dissolved in ketone solvents such as ethyl methyl ketone, isopropyl methyl ketone, and cyclohexanone (solubility: 3 mg). / 100ml). This means that, in the cyanine dye represented by the general formula 1, those having a relatively long chain length of R ₁ and R ₂ are less restricted by the solvent, and a solution having a desired concentration according to the application can be relatively easily prepared. While they can be prepared, the relatively short chain lengths of R ₁ and R ₂ indicate that the use is somewhat limited by the solvent.

[0069]

As described above, the present invention relates to the creation of a cyanine dye in which the same or different cyclic groups having an indole structure are bonded to both ends of a trimethine chain having a squarylium structure, and its industrial usefulness. It is based on the discovery of a unique property. The cyanine dye of the present invention efficiently absorbs visible light in the yellow to red range, and most of the dyes are well soluble in general-purpose organic solvents. However, the cyanine dye of the present invention can be used alone or together with another organic dye compound as a light absorber, for example, clothing articles, bedclothing articles,
By applying to sanitary articles, optical filters, etc., the light transmittance or light reflectivity of those articles is adjusted to a desired wavelength or degree, or the light transmitted or reflected by the articles has a desired chromaticity, color tone, There are benefits that can be adjusted to color and texture. Furthermore, since the cyanine dye of the present invention absorbs visible light in the yellow to red range, it is useful, for example, as a light absorber or sensitizer in the field of optoelectronics such as photochemical polymerization or laser recording, and Those emitting visible light can also be advantageously used as luminescent agents in organic electroluminescence and dye lasers.

Such useful cyanine dyes can be produced in desired amounts by the method of the present invention via a step of reacting an indole compound with squaric acid.

The present invention having such remarkable effects can be said to be a significant invention that greatly contributes to the art.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Sadaharu Suga 1-3-2 Shimoishii, Okayama City, Okayama Prefecture F-term in Hayashibara Biochemical Laboratory Co., Ltd. 4H056 DD03 EA15 FA05

Claims (7)

[Claims] 1. A cyanine dye in which the same or different cyclic groups having an indole structure are bonded to both ends of a trimethine chain having a squarylium structure. 2. The cyanine dye according to claim 1, represented by the general formula 1. Embedded image In the general formula 1, R ₁ and R ₂ represent the same or different aliphatic hydrocarbon groups, and these aliphatic hydrocarbon groups may have a substituent. R ₃ and R ₄ represent the same or different suitable substituents. Z ₁ and Z ₂ represent the same or different cyclic groups for completing the indole structure, and these cyclic groups may have one or more substituents. 3. The cyanine dye according to claim 2, wherein the sum of the carbon numbers of R ₁ and R ₂ in the general formula 1 exceeds 2. 4. The cyanine dye according to claim 1, which is substantially soluble in an ether-based and / or ketone-based organic solvent at 20 ° C. 5. The cyanine dye according to claim 1, which absorbs visible light in a yellow to red range. 6. A light absorber comprising the cyanine dye according to claim 1. 7. R ₁ , R ₃ and Z ₁ corresponding to general formula ₁
A step of reacting a compound represented by the general formula 2 having the general formula 2 with a compound represented by the general formula 3 having R ₂ , R ₄ and Z ₂ corresponding to the general formula 1 and squaric acid. 6. The method for producing a cyanine dye according to any one of 1 to 5. Embedded image Embedded image