WO2010032395A1

WO2010032395A1 - Rare earth complex nanocrystals and applications thereof

Info

Publication number: WO2010032395A1
Application number: PCT/JP2009/004411
Authority: WO
Inventors: 長谷川靖哉; 河合壯; 中川哲也
Original assignee: 国立大学法人奈良先端科学技術大学院大学
Priority date: 2008-09-19
Filing date: 2009-09-07
Publication date: 2010-03-25

Abstract

Provided are light-emitting materials containing rare earth complex nanocrystals. The nanocrystals of the rare earth complex are preferably dispersed or suspended, and light emission efficiency is improved by using the rare earth complex in the form of crystals, and in the form of nanocrystals, in particular. A high level of light emission can be obtained, even with extremely weak exciting light by exciting such light-emitting materials with ultraviolet light. Thus, the light emission efficiency of the rare earth complex can be improved, and light-emitting materials with excellent light emission efficiency can be developed.

Description

Rare earth complex nanocrystals and their use

The present invention relates to a rare earth complex having luminescent properties, and more particularly to a rare earth complex nanocrystal, a luminescent material and a light emitting device using the nanocrystal.

It is known that some rare earth ions emit light in a wide wavelength range from ultraviolet to infrared. These luminescences are based on electronic transitions derived from f-orbitals that are not easily affected by external fields such as ligand fields. For this reason, the wavelength width of the emission band is very narrow compared to organic phosphors and the like, and in principle, the color purity is extremely useful. In addition, organic phosphors are inferior in stability to heat, light, and excitation. Moreover, since rare earth ions are non-toxic, they are easy to use industrially. Thus, since rare earth ions have excellent characteristics, rare earth complexes in which various ligands are coordinated with rare earth ions are used in various applications. Specifically, it is used for various applications such as luminescent ink and organic electroluminescence element.

In addition, in order to make it possible to apply rare earth ions having such excellent characteristics to a wider range of fields, various studies have been conducted on rare earth ions and rare earth complexes. For example, recently, the present inventors have clarified that the emission intensity of rare earth ions in a rare earth complex varies depending on the type of ligand coordinated to the rare earth complex (see Non-Patent Document 1). Non-Patent Document 1 discloses that when the ligand coordinated to Eu (III) is variously changed, the emission characteristics of the complex change depending on the structure of the ligand. Furthermore, the present inventors have developed many rare earth complexes so far (see, for example, Patent Documents 1 to 4).

International Publication WO98 / 40388 (International Publication Date: September 17, 1998) Japanese Patent Publication “Japanese Patent Laid-Open No. 2000-63682 (Publication Date: February 29, 2000)” Japanese Patent Publication “Japanese Patent Application Laid-Open No. 2003-81986 (Publication Date: March 19, 2003)” Japanese Patent Publication “JP 2008-31120 A (publication date: February 14, 2008)”

Thus, various technologies using rare earth complexes have been developed. However, the luminous efficiency of the rare earth complexes used so far is 40-50% at most, and the excitation energy is not effectively utilized.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a light-emitting material having improved light emission efficiency and improved light emission efficiency of the rare earth complex.

The luminescent material according to the present invention has the general formulas (I) to (III)

It is characterized by containing the nanocrystal of the rare earth complex represented by either. In the luminescent material according to the present invention, the nanocrystals are more preferably dispersed or suspended. In the above general formulas (I) to (III), Ln is a rare earth atom, and R ₁ to R ₄ and R ₆ may be the same as or different from each other, and the number of carbon atoms having a straight or branched chain An alkyl group of 20 or less, an alkenyl group or an alkynyl group, a cycloalkyl group of 20 or less carbon atoms, a cycloalkenyl group, an aryl group or a heteroaryl group, a heterocyclic ring (excluding thiophene), a halogen group, or a hydroxyl group A sulfonic acid group, a carbonyl group, a nitro group, a cyano group or an amino group, and R ₅ and R ₇ may be the same or different from each other, and have 20 or less carbon atoms having a straight or branched chain An alkylene group, an arylene group, an alkenyl group or an alkynyl group, a cycloalkyl group having 20 or less carbon atoms, a cycloalkenyl group, an An Lumpur or heteroaryl group or an oxygen, nitrogen or sulfur, or heterocyclic ring, (except thiophene.), X ₁ and X _2, which may be the same or different from each other, it contains no hydrogen atoms A straight chain or branched chain group having 20 or less carbon atoms, or a heterocyclic ring (excluding thiophene), and Y is hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group. , A cyano group or an amino group, a straight chain or branched chain alkyl group or aryl group having 20 or less carbon atoms, or a group consisting of a straight chain or branched chain having 20 or less carbon atoms that does not contain a hydrogen atom, Alternatively, it is a heterocyclic ring (excluding thiophene), n = 1 or 2, and m = 2, 3 or 4.

Since the rare earth complex used in the present invention has the structure as described above, light energy for exciting the rare earth ions is difficult to be released as thermal energy, and as a result, the rare earth ions are sufficiently excited, Strong emission intensity is maintained. In addition, since the rare earth complex exists in a nanocrystalline state, it is not easily affected by the dispersion medium (for example, a polymer or the like), and exhibits strong light emission characteristics. Further, since the rare earth complex in a crystalline state is hardly affected by oxygen or water, it has high durability.

In the luminescent material according to the present invention, the crystal size is preferably 200 nm or less, and more preferably 100 nm or less because the visible light transmittance is very high.

Furthermore, the luminescent material according to the present invention includes a rare earth complex crystal represented by any one of the above-described general formulas (I) to (III) in order to emit light using excitation by ultraviolet light. It is characterized by that. Since the extinction coefficient in the ultraviolet light of the rare earth complex existing in the crystalline state is several orders of magnitude higher than the extinction coefficient in the visible light, high emission can be provided by emitting light using excitation by ultraviolet light. . The ultraviolet light applied to the luminescent material according to the present invention is preferably 370 nm or less, and more preferably 200 to 365 nm.

The ink according to the present invention is characterized by containing the above-described luminescent material. The ink according to the present invention may be used for offset printing or inkjet.

The pigment according to the present invention is characterized by containing the above-mentioned luminescent material. Art objects to which the pigments according to the invention are applied are also within the scope of the invention.

The information identification medium according to the present invention is characterized by containing the above-mentioned luminescent material. The information identification medium according to the present invention may be applied to an ID card.

The light emitting device according to the present invention includes a rare earth complex crystal represented by any one of the above general formulas (I) to (III), a light emitting material containing the crystal, and a light source capable of emitting light in the ultraviolet region. It is characterized by having. More preferably, the light-emitting device according to the present invention further includes a filter that blocks visible light to infrared light from the light source. In the present invention, the crystal of the rare earth complex is preferably a nanocrystal, the crystal size is more preferably 200 nm or less, and further preferably 100 nm or less.

As described above, since the crystal of the rare earth complex used in the present invention has an absorption coefficient in ultraviolet light that is several orders of magnitude higher than that in visible light, the light emitting device according to the present invention is a light source that emits visible light. It can provide much stronger light than those equipped with.

The method of emitting light of the rare earth complex according to the present invention is to irradiate the crystal of the rare earth complex represented by any one of the above general formulas (I) to (III) or a light emitting material containing the crystal with ultraviolet light. It includes the process of performing.

By using the present invention, it is possible to obtain light emission with higher color purity and higher light emission intensity than inorganic light emitters. Accordingly, it is possible to provide a luminescent polymer and a luminescent ink with higher emission intensity, and an illumination device, a signal device, and a display device with higher emission intensity.

It is a figure which shows the XRD spectrum of the rare earth complex nanocrystal used for one Embodiment of this invention.

[Luminescent material]
The present invention provides a luminescent material comprising nanocrystals of a rare earth complex. In one embodiment, the luminescent material according to the present invention is a composition containing dispersed nanocrystals of the rare earth complex described above. In another embodiment, the luminescent material according to the present invention is a composition containing suspended nanocrystals of the rare earth complex described above. In such a composition, the rare earth complex mentioned above may be contained singly or in combination. The content of the rare earth complex in the luminescent material according to the present embodiment is not particularly limited, and can be appropriately set according to the specific application and the type of the dispersion medium.

In the rare earth complex used in the present invention, a specific ligand is coordinated to a rare earth ion. The rare earth ion is not particularly limited as long as it is a rare earth metal ion, but is preferably a trivalent lanthanoid ion, and particularly Eu ³⁺ , Sm ³⁺ , Tb ³⁺ , Yb ³⁺ , Nd ³⁺ , Ce ³⁺ , Dy ^3+. More preferably, Er ³⁺ , Pr ³⁺ or Tm ³⁺ . In the present invention, by changing the rare earth ions, the excitation wavelength, emission intensity, and emission wavelength of the rare earth complex can be changed, but in order to emit light using excitation by ultraviolet light that has not been conventionally employed. The rare earth ions used in the present invention are more preferably Eu ³⁺ , Sm ³⁺ , Tb ³⁺ , Yb ³⁺ or Nd ³⁺ .

It is characterized by including the nanocrystal of the rare earth complex represented by either, It is preferable that the said nanocrystal is disperse | distributed or suspended.

Ln in the general formulas (I) to (III) is a rare earth atom, and the rare earth atom is preferably Eu, Sm, Tb, Yb, Nd, Ce, Dy, Er, Pr, or Tm, and Eu, Sm More preferably, Tb, Yb or Nd.

As substituents represented by the general formulas (I) to (III), R ₁ to R ₄ and R ₆ may be the same as or different from each other, and may be a linear or branched alkyl group or alkenyl group. Or an alkynyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group or a heteroaryl group, a heterocyclic ring (excluding thiophene), a halogen group, a hydroxyl group, a sulfonic acid group, a carbonyl group, a nitro group, a cyano group, or an amino group R ₅ and R _{7, which} may be the same or different from each other, are a linear or branched alkylene group, arylene group, alkenyl group or alkynyl group, or cycloalkyl group, cycloalkenyl group An aryl or heteroaryl group, or oxygen, nitrogen or sulfur, or a heterocyclic ring (thiophene) Excluding.), And, X ₁ and X _2, which may be the same or different from each other, group having straight or branched does not contain a hydrogen atom or a heterocycle (excluding thiophene.), Y represents hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group, cyano group or amino group, or linear or branched alkyl group or aryl group, or hydrogen atom. It is a straight chain or branched chain group that does not contain, or a heterocyclic ring (excluding thiophene).

The alkyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 8 carbon atoms. The alkenyl group and alkynyl group preferably have 2 to 20 carbon atoms, and more preferably 2 to 8 carbon atoms. The cycloalkyl group and cycloalkenyl group preferably have 3 to 20 carbon atoms, and more preferably 4 to 11 carbon atoms. The aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms, and further preferably a phenyl group, a naphthyl group, a biphenyl group, an anthracenyl group, or a phenanthryl group.

The heteroaryl group preferably has 3 to 20 carbon atoms, and more preferably 4 to 11 carbon atoms. The heterocyclic ring is preferably a 5-membered or 6-membered ring, a single ring or 2 to 6 condensed rings. Examples of the 5-membered heterocyclic ring include furan, pyrrole, oxazole, isoxazole, thiazole, imidazole, and pyrazole. Examples of the 6-membered heterocyclic ring include pyridine, pyran, triazine, and the like. Examples of the 6-membered condensed ring include benzofuran, coumarin, benzopyran, carbazole, xanthene, quinoline, dibenzofuran, and the like, but are not limited thereto as long as they do not have a thiophene structure.

Furthermore, the alkylene group preferably has 1 to 20 carbon atoms, and more preferably 1 to 8 carbon atoms. The arylene group preferably has 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably a phenylene group, a naphthylene group, a biphenylene group, an anthracenylene group, or a phenanthrylene group.

Examples of the C ₁ -C ₂₀ linear or branched group that does not contain a hydrogen atom include perhalogenated alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, cycloalkenyl groups, aromatic groups, Examples include, but are not limited to, a heteroaromatic group or an aralkyl group, and may be an ether, ester, or ketone in which one or more —O— or the like is interposed between any of these C—C bonds. . In addition, one or more of the halogen atoms bonded to the aromatic ring of the perhalogenated aromatic group, the perhalogenated heteroaromatic group, or the perhalogenated aralkyl group is a substituent that does not contain a hydrogen atom (for example, cyano, nitro, Nitroso, C ₁ -C ₄ perhalogenated alkoxy, C ₂ -C ₅ perhalogenated alkoxycarbonyl, C ₂ -C ₂₀ perhalogenated alkylcarbonyloxy, etc.). The group having a C ₁ to C ₂₀ straight or branched chain that does not contain a hydrogen atom is more preferably a perfluorinated alkyl group or a perfluorinated alkenyl group, and is preferably C ₁ to C _4. More preferred is CF ₃ .

Y is more preferably hydrogen, deuterium or halogen, and most preferably hydrogen. Further, n = 1 or 2, and m = 2, 3 or 4.

It should be noted that those skilled in the art who read this specification will easily understand that the above substituents can be appropriately selected within a range that does not interfere with coordination through 1 to 3 phosphine oxides.

In one embodiment, the rare earth complex used in the present invention is:

Or

It can be.

In addition, the dispersion medium used for the luminescent material according to the present embodiment is not particularly limited, and a preferable medium can be appropriately selected depending on the application. Examples of preferable media include resins, inorganic materials, and organic-inorganic hybrid materials. Examples of the resin include polyimide resin, polyamide resin, polymethyl methacrylic resin, polyacrylate, polystyrene resin, polyethylene naphthalate resin, polyester resin, polyurethane, polycarbonate resin, epoxy resin, polyethylene terephthalate resin, and chloride. Examples thereof include vinyl resins, vinylidene chloride resins, acrylonitrile butadiene styrene (ABS) resins, acrylonitrile styrene (AS) resins, cycloolefin resins, siloxane polymers, and halides or deuterides thereof. These resins may be used alone or in combination of two or more. Examples of the inorganic material include glass prepared by a sol-gel method.

Furthermore, an additive for imparting a specific function may be further added to the luminescent material according to the present embodiment, depending on its application. Examples of such additives include additives such as antioxidants, inorganic fillers, stabilizers, antistatic agents, dyes, pigments, flame retardants, inorganic fillers, and elastomers for improving impact resistance. it can. Moreover, additives, such as a lubricant, can also be added for the purpose of improving the workability of the luminescent material according to this embodiment. Furthermore, a leveling agent may be added when casting the luminescent material which concerns on this embodiment, and shape | molding a cast film.

Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,2′-dioxy-3,3′-di-t-butyl-5,5′-dimethylphenylmethane. Tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) Butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl-benzene, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-dioxy-3,3'-di-t-butyl-5,5'-diethylphenylmethane, 3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4- Hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxospiro [5,5] undecane, tris (2,4-di-t-butylphenyl) phosphite, cyclic neo Pentanetetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite, 2,2-methylenebis And (4,6-di-t-butylphenyl) octyl phosphite.

Examples of the inorganic filler include calcium carbonate, carbon fiber, and metal oxide.

Examples of the leveling agent include a fluorine-based nonionic surfactant, a special acrylic resin leveling agent, and a silicone leveling agent.

The shape of the luminescent material according to the present embodiment is not particularly limited, and examples thereof include a plate shape, a powder shape, a granular shape, a granular shape, a paste shape, a liquid shape, and an emulsion shape. Since the luminous efficiency is improved by existing in a crystalline state, a plate shape, a powder shape, a granular shape, and a granular shape are preferable.

The method for producing the luminescent material according to the present embodiment is not particularly limited, and a suitable method may be selected as appropriate according to the composition, shape, application, and the like. For example, when the luminescent material is a powder, the rare earth complex, the medium, and, if necessary, other additives as exemplified above are mixed in a twin screw extruder, Brabender, roll kneader, etc. It can be produced by a method of pelletizing using an extruder or a method of further pulverizing pellets by a pulverizer to form a powder.

In another embodiment, the luminescent material according to the present invention may be in the form of a carrier carrying the above-mentioned rare earth complex nanocrystals on the surface. One kind of the above-mentioned rare earth complex may be supported on such a support, or a plurality of kinds may be mixed and supported. The amount of the rare earth complex supported on the luminescent material according to the present embodiment is not particularly limited, and can be appropriately set according to the specific application and the type of the carrier.

The manufacturing method of the luminescent material according to the present embodiment is not particularly limited. For example, it can be produced by casting a dispersion or suspension of a luminescent material on a carrier (polymer or substrate) and subjecting the resulting solution layer to removal treatment of the dispersion medium or the like. The method for casting on a carrier is not particularly limited.

Also, it can be manufactured by forming a coating film of the luminescent material according to the present embodiment on the surface of the carrier. In order to form a coating film of a luminescent material on the surface of a carrier, a conventionally known method (for example, brush coating method, dip coating method, spray coating method, plate coating method, spinner coating method, bead coating method, curtain coating method) And other wet methods, gravure printing methods, screen printing methods, offset printing methods, letterpress printing methods, and other film forming methods) may be employed.

In addition, the carrier used for the luminescent material according to the present embodiment is not particularly limited, and a preferable carrier can be appropriately selected according to the application. Preferred carriers include the above-described resins, inorganic materials, organic-inorganic hybrid materials, and the like.

[Light emitting device and light emitting method]
The present invention provides a light-emitting device including a rare-earth complex crystal or a light-emitting material containing the crystal, and a light source capable of emitting light in the ultraviolet region. The rare earth complex used in the light emitting device according to the present invention is not particularly limited as long as it is described above.

In the light emitting device according to the present invention, the light source is not particularly limited as long as it is a light source capable of emitting light in the ultraviolet region. For example, a deuterium lamp, a tungsten lamp, an ultraviolet LED, a xenon lamp, a mercury lamp, a black light, a halogen lamp. And short wavelength semiconductor lasers. As the light source used in the present invention, a light source that irradiates only ultraviolet light is preferable. However, the light emitting device according to the present invention includes a filter that blocks visible light to infrared light together with the various light sources described above. Only ultraviolet light can be supplied.

The present invention also provides a method for causing a rare earth complex to emit light. The light-emitting method according to the present invention includes a step of irradiating ultraviolet light to a crystal of a rare earth complex or a light-emitting material containing the crystal. There is no particular limitation.

[Further use of luminescent materials]
The rare earth complex used in the present invention has different emission characteristics depending on the type of organic ligand and rare earth ions constituting the complex. That is, each of the rare earth complexes used in the present invention has unique emission characteristics. Further, by changing the combination of the organic ligand and the rare earth ion, the light emission characteristics of the rare earth complex used in the present invention can be changed.

• Encryption can be generated based on various emission characteristics. Moreover, such a code | symbol can be deciphered based on the light emission characteristic of this rare earth complex. Thus, the luminescent material according to the present invention can be used as an information identification medium.

That is, the present invention provides an information recording medium (for example, an ID card) for recording or storing information and signals. An information recording medium according to the present invention is characterized by containing the above-described luminescent material. By utilizing the light emission characteristics of the rare earth complex used in the present invention, the luminescent material according to the present invention can be used for an information identification medium such as an ID card.

The shape and form of the information identification medium according to the present invention are not particularly limited. Specifically, the information identification medium according to the present invention can be in the shape and form of, for example, a card, a film, a seal, an armband, etc., molded from a resin containing the luminescent material according to the present invention. In addition, images, figures, and characters printed or printed using the ink containing the luminescent material according to the present invention can be used as the information identification medium.

In addition, although the kind of rare earth complex contained in the information identification medium based on this invention may be one, it is preferable that it is multiple types. For example, the light emission pattern described above includes not only light emission from a rare earth complex composed of a single rare earth ion (eg, Eu ³⁺ ) but also light emission from a rare earth complex composed of other rare earth ions (eg, Sm ³⁺ , Tb ^3+, etc.). It may be. A new information recording medium can also be obtained by using a rare earth complex nanocrystal having a photochromic ligand. That is, a change in light emission characteristics (intensity, etc.) can also be used for identification. As a result, the discrimination power (security) of the information identification medium can be enhanced.

Without being limited to application to an information identification medium, inks for printing or printing images, figures and characters, and pigments for producing artworks such as paintings are also within the scope of the present invention. Are easily understood by those skilled in the art who have read this specification. That is, the present invention provides an ink or pigment. The ink or pigment according to the present invention is characterized by containing the above-described luminescent material. The ink according to the present invention may be used for offset printing or inkjet. In addition, art objects coated with the pigment according to the present invention are also within the scope of the present invention.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

In addition, all the academic literatures and patent literatures described in this specification are incorporated herein by reference.

[Synthesis of Complex 1 (Eu (hfa) ₃ (H ₂ O) ₂ )]
Europium acetate (1 g of white crystals) was placed in an Erlenmeyer flask (50 mL) containing a stirrer chip, and 10 mL of ion-exchanged water was added to completely dissolve europium acetate. To this solution, hexafluoroacetylacetone (transparent liquid 2 g) was added dropwise using a Pasteur pipette. The cloudy solution was stirred at room temperature for 1 hour. After stirring, the powder recovered by filtration was washed several times with water. It was confirmed by UV irradiation that this powder (Eu (hfa) ₃ (H ₂ O) ₂ complex) emitted red light. In addition, terbium acetate was used instead of europium acetate to obtain a Tb (hfa) ₃ complex emitting green light.

[Synthesis of Complex 2 (Eu (hfa) ₃ (TPPO) ₂ )]
In a 200 mL eggplant-shaped flask, 1.5 g (2 mmol) of Complex 1 was dissolved in methanol (100 mL). 0.8 g (3 mmol) of triphenylphosphine oxide (TPPO) was dissolved in methanol (10 mL) and added to the solution in the eggplant type flask. A cooling tube was attached to the eggplant-shaped flask, and reflux with methanol was performed at 80 ° C. After completion of the reaction, methanol in the flask was removed with an evaporator. Hexane was added and powder precipitation was performed, followed by drying.

[Synthesis of BIPHEPO]
0.5 g of 2,2′-bis (phenylphosphino) biphenyl (BIPHEP; Tokyo Chemical Industry Co., Ltd.) was dissolved in dichloromethane (30 mL), and a small amount of 30% aqueous hydrogen peroxide was added dropwise under ice cooling. . After stirring for 3 hours, the mixture was extracted with water and dichloromethane, and the extracted dichloromethane phase was washed with water. After washing, the dichloromethane phase was dried over magnesium sulfate to remove water. Subsequently, it filtered with the filter paper and the dichloromethane was distilled off from the collect | recovered filtrate with the evaporator. Hexane was added to the obtained solid for reprecipitation, and dichloromethane was again distilled off with an evaporator. The obtained solid was dried on a vacuum line for 3 hours and recrystallized with water / ethanol to obtain BIPHEPO (1,1′-biphenyl-2,2′-diylbis (diphenylphosphine oxide)).

[Synthesis of Complex 3 (Eu (hfa) ₃ (BIPHEPO))]
In a 200 mL eggplant-shaped flask, 1.5 g (2 mmol) of Complex 1 was dissolved in methanol (100 mL). 0.8 g (3 mmol) of BIPHEPO was dissolved in methanol (10 mL) and added to the solution in the eggplant type flask. A cooling tube was attached to the eggplant-shaped flask, and reflux with methanol was performed at 80 ° C. After completion of the reaction, methanol in the flask was removed with an evaporator. Hexane was added and powder precipitation was performed, followed by drying.

[Evaluation of rare earth complex nanocrystals]
The synthesized complex was dissolved in a small amount of methanol, and this solution was added dropwise to water. The obtained powder was vacuum dried at room temperature (0.1 torr) and dried. The crystallite sizes according to the Scherrer equation of complexes 1 to 3 were 20 nm, 34 nm and 34 nm, respectively (measured with signals of 24.1 °, 17.06 ° and 10.68 °, respectively). The XRD spectrum of Complex 2 is shown in FIG. Furthermore, the characteristics of these complexes were evaluated for the following items by measuring absolute luminescence quantum efficiency using an integrating sphere (Hamamatsu Photonics).
[1] The quantum efficiency between the powder state and the solution state was compared, and the effect of the powder (nanocrystal) was confirmed. Specifically, the emission quantum yield by photoexcitation at 350 nm at room temperature was compared between a powdered rare earth complex and a rare earth complex dissolved in 0.1 mM in acetone. The emission quantum yield of Complex 1 was 37% in the solution state and 15% in the powder state. However, for complex 2 and complex 3, the emission quantum yield of 59% in the solution state was improved to 94% in the powder state. In the powder (nanocrystal), it is considered that non-radiative deactivation due to molecular vibration was suppressed.
[2] The excitation wavelength dependence in the powder state was confirmed. Specifically, the quantum yield of light emission by photoexcitation at 310 to 360 nm at room temperature was examined. As a result, it was found that the quantum efficiency was not dependent on the excitation wavelength.
[3] It was confirmed whether there was a difference in measurement results due to a difference in powder shape. Specifically, the powder was subjected to measurement in a pellet type or a pile type. As a result, there was no difference in measurement results due to differences in powder shape. Moreover, although it measured using 2 mg or 20 mg powder, there was no difference in the measurement result by the difference in quantity. Various samples were measured, and it was confirmed that the nanocrystal effect was observed in all samples.

The results are shown in the table below.

From the above, it was confirmed that the quantum efficiency of the powder can be normally evaluated and that the quantum efficiency depends on the complex structure.

Luminescence efficiency can be greatly improved by using rare earth complexes in a nanocrystalline state. Therefore, this invention can provide the luminescent ink and / or organic electroluminescent element which were far superior to the past.

Claims

Formulas (I) to (III)

(In the formula, Ln is a rare earth atom, and R 1 to R 4 and R 6 may be the same or different from each other, and are a linear or branched C 1 to C 20 alkyl group, C alkenyl group or C 2 ~ alkynyl groups to C 20 of 2 ~ C 20 or C 3 cycloalkyl group ~ C 20, C 3 cycloalkenyl group ~ C 20, aryl group of C 6 ~ C 20,, C 3 ~ A C 20 heteroaryl group or a heterocyclic ring (excluding thiophene), or a halogen group, a hydroxyl group, a sulfonic acid group, a carbonyl group, a nitro group, a cyano group or an amino group, and R 5 and R 7 are the same as each other or different even an alkylene group, an arylene group having a straight-chain or branched C 1 ~ C 20, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl Group, an aryl group or a heteroaryl group or an oxygen, nitrogen or sulfur, or heterocyclic ring, (except thiophene.), X 1 and X 2, which may be the same or different from each other, include a hydrogen atom Or a group having a straight chain or branched chain of C 1 to C 20 or a heterocyclic ring (excluding thiophene), and Y is hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group A group consisting of a C 1 -C 20 straight chain or branched chain containing no hydrogen atom, a group, a cyano group or an amino group, or a C 1 -C 20 straight chain or branched alkyl group or aryl group Or a heterocyclic ring (excluding thiophene), n = 1 or 2, and m = 2, 3 or 4.
A luminescent material comprising a nanocrystal of a rare earth complex represented by any one of:
The luminescent material according to claim 1, wherein the nanocrystal is dispersed or suspended.
The luminescent material according to claim 1 or 2, wherein the crystal size is 200 nm or less.
Formulas (I) to (III)

(In the formula, Ln is a rare earth atom, and R 1 to R 4 and R 6 may be the same or different from each other, and are a linear or branched C 1 to C 20 alkyl group, C alkenyl group or C 2 ~ alkynyl groups to C 20 of 2 ~ C 20 or C 3 cycloalkyl group ~ C 20, C 3 cycloalkenyl group ~ C 20, aryl group of C 6 ~ C 20,, C 3 ~ A C 20 heteroaryl group or a heterocyclic ring (excluding thiophene), or a halogen group, a hydroxyl group, a sulfonic acid group, a carbonyl group, a nitro group, a cyano group or an amino group, and R 5 and R 7 are the same as each other or different even an alkylene group, an arylene group having a straight-chain or branched C 1 ~ C 20, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl Group, an aryl group or a heteroaryl group or an oxygen, nitrogen or sulfur, or heterocyclic ring, (except thiophene.), X 1 and X 2, which may be the same or different from each other, include a hydrogen atom Or a group having a straight chain or branched chain of C 1 to C 20 or a heterocyclic ring (excluding thiophene), and Y is hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group A group consisting of a C 1 -C 20 straight chain or branched chain containing no hydrogen atom, a group, a cyano group or an amino group, or a C 1 -C 20 straight chain or branched alkyl group or aryl group Or a heterocyclic ring (excluding thiophene), n = 1 or 2, and m = 2, 3 or 4.
A luminescent material for emitting light using excitation by ultraviolet light, comprising a rare earth complex crystal represented by any one of the above.
The luminescent material according to claim 4, wherein the wavelength range of the excitation light is 200 to 370 nm.
The luminescent material according to claim 4 or 5, wherein the crystal size is 200 nm or less.
An ink containing the luminescent material according to any one of claims 4 to 6.
The ink according to claim 7, which is for offset printing.
The ink according to claim 7, which is for inkjet.
A pigment containing the luminescent material according to any one of claims 4 to 6.
Art work to which the pigment according to claim 10 is applied.
An information identification medium containing the luminescent material according to any one of claims 4 to 6.
The information identification medium according to claim 12, which is an ID card.
Formulas (I) to (III)

(In the formula, Ln is a rare earth atom, and R 1 to R 4 and R 6 may be the same or different from each other, and are a linear or branched C 1 to C 20 alkyl group, C alkenyl group or C 2 ~ alkynyl groups to C 20 of 2 ~ C 20 or C 3 cycloalkyl group ~ C 20, C 3 cycloalkenyl group ~ C 20, aryl group of C 6 ~ C 20,, C 3 ~ A C 20 heteroaryl group or a heterocyclic ring (excluding thiophene), or a halogen group, a hydroxyl group, a sulfonic acid group, a carbonyl group, a nitro group, a cyano group or an amino group, and R 5 and R 7 are the same as each other or different even an alkylene group, an arylene group having a straight-chain or branched C 1 ~ C 20, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl Group, an aryl group or a heteroaryl group or an oxygen, nitrogen or sulfur, or heterocyclic ring, (except thiophene.), X 1 and X 2, which may be the same or different from each other, include a hydrogen atom Or a group having a straight chain or branched chain of C 1 to C 20 or a heterocyclic ring (excluding thiophene), and Y is hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group A group consisting of a C 1 -C 20 straight chain or branched chain containing no hydrogen atom, a group, a cyano group or an amino group, or a C 1 -C 20 straight chain or branched alkyl group or aryl group Or a heterocyclic ring (excluding thiophene), n = 1 or 2, and m = 2, 3 or 4.
A light emitting device comprising: a rare earth complex crystal represented by any one of the above or a luminescent material containing the crystal; and a light source capable of emitting light in an ultraviolet region.
The light-emitting device according to claim 14, further comprising a filter that blocks visible light to infrared light.
Formulas (I) to (III)

(In the formula, Ln is a rare earth atom, and R 1 to R 4 and R 6 may be the same or different from each other, and are a linear or branched C 1 to C 20 alkyl group, C alkenyl group or C 2 ~ alkynyl groups to C 20 of 2 ~ C 20 or C 3 cycloalkyl group ~ C 20, C 3 cycloalkenyl group ~ C 20, aryl group of C 6 ~ C 20,, C 3 ~ A C 20 heteroaryl group or a heterocyclic ring (excluding thiophene), or a halogen group, a hydroxyl group, a sulfonic acid group, a carbonyl group, a nitro group, a cyano group or an amino group, and R 5 and R 7 are the same as each other or different even an alkylene group, an arylene group having a straight-chain or branched C 1 ~ C 20, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl Group, an aryl group or a heteroaryl group or an oxygen, nitrogen or sulfur, or heterocyclic ring, (except thiophene.), X 1 and X 2, which may be the same or different from each other, include a hydrogen atom Or a group having a straight chain or branched chain of C 1 to C 20 or a heterocyclic ring (excluding thiophene), and Y is hydrogen, deuterium, halogen group, hydroxyl group, sulfonic acid group, carbonyl group, nitro group A group consisting of a C 1 -C 20 straight chain or branched chain containing no hydrogen atom, a group, a cyano group or an amino group, or a C 1 -C 20 straight chain or branched alkyl group or aryl group Or a heterocyclic ring (excluding thiophene), n = 1 or 2, and m = 2, 3 or 4.
A method of emitting light of a rare earth complex, comprising a step of irradiating a crystal of the rare earth complex represented by any one of the above or a luminescent material containing the crystal with ultraviolet light.