JP4992021B2 - Strongly luminescent rare earth complex - Google Patents

Description

  The present invention relates to a rare earth complex that emits fluorescence when irradiated with predetermined excitation light.

  The present inventors have found that a composition containing a + 3-valent rare earth ion complex has excellent light emission characteristics. Of these, the lanthanoid (III) complex exhibits particularly excellent luminescent properties. This seems to be because amplified luminescence occurs when the lanthanoid ion undergoes an ff transition (see Non-Patent Document 1).

  Since lanthanoid (III) complexes exhibit particularly excellent light emission properties, polymer fiber lasers, liquid lasers, plastic thin film lasers, etc. can be obtained by using complexes of lanthanoid (III) complexes that have further laser oscillation conditions. It is thought that it can also be produced. In fact, laser oscillation has been attempted in the past using a lanthanoid (III) complex (see Non-Patent Document 2).

  Non-Patent Document 2 confirms that the lanthanoid (III) complex oscillates by applying a very large energy of 1700 J. However, the threshold energy of 1700 J is industrially excessive, and it is impractical to produce a laser oscillation device using the lanthanoid (III) complex used in this research. In order to manufacture a laser oscillation device that can be used practically, it is necessary to use a complex having a small threshold energy.

Here, the threshold value ΔN _th is expressed by equation (a).

In equation (a), ΔN ₀ is the excitation energy, B is the Einstein coefficient, ρ _s is the energy density, and T is the relaxation time of the inversion distribution. For this reason, in order to reduce the threshold value, the energy density ρs in the steady state must be increased. In order to increase ρ _s , the emission quantum yield must be increased.

Furthermore, in order to produce a laser with higher performance, it is necessary to increase the value of the stimulated emission cross section σ _p representing the laser performance. Here, σ _p is expressed by equation (b).

In equation (b), A (bJ ′: aJ) is the spontaneous emission coefficient between levels, c is the speed of light, λ _p is the peak wavelength of the oscillating laser, n is the refractive index of the medium, and Δλ _eff is the effective half-width. It is. The effective half-width indicates a spectrum width at half the peak intensity. From this equation, it can be seen that a rare earth complex having a small Δλ _eff value and a sharp peak must be used to produce a high-performance laser.

In order to obtain a rare earth complex suitable for laser oscillation, it is necessary to increase the emission quantum yield as described above. The relationship between the emission rate and the emission quantum yield is [Emission rate] = [Emission quantum yield] / [Emission lifetime]
However, if the structure of the complex is asymmetric, the ff transition becomes an allowable transition, and the emission rate increases. Accordingly, the emission quantum yield can be increased by making the complex structure an asymmetric structure. Here, the asymmetric structure refers to a complex structure in which a ligand is selected so that the structure of the entire complex takes an asymmetric form.

In addition, the complex structure should be a low-vibration structure, designed so that molecular vibrations are reduced, and the excitation of electrons excited by molecular vibrations is suppressed, resulting in a structure that increases the emission quantum yield. Is preferred. By the complex structure and low-vibration structure, it is possible to increase the Einstein coefficient B, and because it is possible to further reduce the threshold .DELTA.N _th.

As a rare earth complex satisfying such conditions, for example, Patent Document 1 discloses a rare earth complex having triphenylphosphine oxide as a ligand. Problems to be overcome in terms of emission intensity, compatibility with a resin, and the like. Was left.
Japanese Patent Laid-Open No. 2003-81986 Shinya Hasegawa, “How to shine neodymium that does not shine in organic media”, “Chemistry and Industry”, 2000, Vol. 53, No. 2, pp. 126-130 "Applied Physics Letters, 1964, Vol. 5, pp. 173-174.

  The present invention has been made in order to solve such problems, and the object of the present invention is to provide a strongly luminescent rare earth complex that has excellent emission characteristics and exhibits a sharp emission spectrum compared to conventional rare earth complexes. There is to do.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a rare earth complex having a specific structure has excellent emission characteristics and exhibits a sharp emission spectrum, and has completed the present invention. That is, the present invention
[1] A strongly luminescent rare earth complex represented by the following general formula (1).

(In the formula, Ln represents a rare earth atom. A, b and c are each a positive integer of 3 or less or 0, but they are not all 0 simultaneously. R ^{1 to} R ¹⁸ may be the same or different. Well, it represents a hydrocarbon group having 1 to 10 carbon atoms, and R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁷ and R ¹⁸ may be bonded to each other to form a ring structure, n is an integer of 1 to 5. Y ¹ and Y ² are The same or different hydrocarbon group having 1 to 20 carbon atoms, amino group, hydroxyl group, nitro group, sulfonic acid group, cyano group, silyl group, phosphonic acid group, diazo group or mercapto group, Z represents a hydrogen atom. Or represents a deuterium atom.)

  [2] A laser oscillation part made of a thin film in which the strong light-emitting rare earth complex of [1] is introduced into a transparent matrix placed on a substrate, and irradiation means for irradiating the laser oscillation part with excitation light And a laser oscillation device.

  [3] An optical functional material comprising a resin, a transparent inorganic material, or a transparent organic-inorganic hybrid material mixed with the strong luminescent rare earth complex of [1].

  [4] A light emitting device comprising: a molded body containing the strong light emitting rare earth complex of [1] above; and an excitation light source.

  ADVANTAGE OF THE INVENTION According to this invention, the strong luminescent rare earth complex which is excellent in the luminescent property than the conventional rare earth complex, and shows a sharp emission spectrum is provided.

Hereinafter, the present invention will be specifically described.
The strongly luminescent rare earth complex of the present invention is represented by the general formula (1).

  In the general formula (1), Ln represents a rare earth atom. More specifically, it represents Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. Of these rare earth atoms, Eu, Tb, Yb, Nd, Er, Sm, Dy or Ce are preferable, and Eu is more preferable.

  In the general formula (1), a, b and c are each a positive integer of 3 or less or 0, but all are not 0 at the same time. a, b and c are preferably positive integers of 2 or less, and preferred combinations of a, b and c include a combination in which one of a, b and c is 2 and the other three are 1, And a combination in which all of a, b and c are 1, and a particularly preferred combination is a combination in which all of a, b and c are 1.

In the general formula (1), R ^{1 to} R ¹⁸ are the same or different hydrocarbon groups having 1 to 10 carbon atoms. R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁷ and R ¹⁸ may be bonded to each other to form a ring structure.

Specific examples of R ^{1 to} R ¹⁸ include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, a 2-butyl group, an n-pentyl group, and a 2-ethylhexyl group, for example, a carbon such as a cyclohexyl group. A cycloalkyl group having 3 to 10 carbon atoms, for example, an alkenyl group having 2 to 10 carbon atoms such as a vinyl group or a propenyl group, a cycloalkenyl group having 3 to 10 carbon atoms such as a cyclohexenyl group, such as a phenyl group or a naphthyl group And a substituted or unsubstituted aryl group having 6 to 10 carbon atoms such as an ethylphenyl group.

R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , Examples of the divalent substituent when R ¹⁷ and R ¹⁸ are bonded to each other to form a ring structure include an alkylene group having 2 to 10 carbon atoms such as an ethylene group, a tetramethylene group, and a pentamethylene group, such as a cyclohexyl group. A cycloalkylene group having 3 to 10 carbon atoms such as a silene group, an alkenylene group having 2 to 10 carbon atoms such as a vinylene group, a cycloalkenylene group having 3 to 10 carbon atoms such as a cyclohexenylene group, such as phenyl Examples thereof include an aralkylene group having 8 to 10 carbon atoms such as an ethylene group.

  When two hydrocarbon groups on the same nitrogen atom do not form a ring structure, among these hydrocarbon groups, an alkyl group having 1 to 10 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable. More preferably, it is a methyl group. In addition, when two hydrocarbon groups on the same nitrogen atom are bonded to each other to form a ring structure, among divalent substituents bonded to the nitrogen atom, an alkylene group having preferably 2 to 8 carbon atoms is preferable. And more preferably a tetramethylene group or a pentamethylene group.

  In the general formula (1), n represents the number of phosphine oxide compounds coordinated to the rare earth metal, and is an integer of 1 to 5, preferably 1 or 2, and more preferably 1.

In the general formula (1), Y ¹ and Y ² are the same or different C 1-20 hydrocarbon group, amino group, hydroxyl group, nitro group, sulfonic acid group, cyano group, silyl group, phosphonic acid group, diazo group. Or represents either a mercapto group. Among these, in the hydrocarbon group having 1 to 20 carbon atoms, part or all of the hydrogen atoms may be substituted with a substituent containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom. .

Specific examples of the hydrocarbon group having 1 to 20 carbon atoms among the groups represented by Y ¹ and Y ² include, for example, a methyl group, an ethyl group, a 2-butyl group, an n-pentyl group, and 2-ethylhexyl. Group, straight chain or branched alkyl group having 1 to 20 carbon atoms such as dodecyl group, for example, cycloalkyl group having 3 to 20 carbon atoms such as cyclohexyl group, adamantyl group, etc., such as vinyl group, allyl group, butenyl group, etc. Straight chain or branched alkenyl group having 2 to 20 carbon atoms, such as cycloalkenyl group having 3 to 20 carbon atoms such as cyclohexenyl group, such as phenyl group, naphthyl group, 4-methylphenyl group, biphenyl group, etc. Aryl group having 6 to 20 carbon atoms, such as aralkyl group having 7 to 20 carbon atoms such as benzyl group and phenethyl group, such as trifluoromethyl group, 2,2,2 C1-C20 hydrocarbon groups substituted by halogen atoms such as trichloroethyl group, perchloro-n-butyl group, perfluorophenyl group, for example, hydroxymethyl group, methoxyethyl group, 2-carbomethoxyethyl group, 2- C1-C20 hydrocarbon group having a substituent containing an oxygen atom such as oxypropyl group, for example, aminomethyl group, N, N-dimethylaminomethyl group, 3-cyanobutyl group, 2-nitropropyl group, diazomethyl group A hydrocarbon group having 1 to 20 carbon atoms having a substituent containing a nitrogen atom such as a hydrocarbon group having 1 to 20 carbon atoms having a substituent containing a sulfur atom such as a mercaptomethyl group or a methyl sulfonate group, for example, A hydrocarbon group having 1 to 20 carbon atoms having a substituent containing a phosphorus atom such as a methyl phosphonate group, such as trimethylsilyl C1-C20 hydrocarbon groups etc. which have a substituent containing silicon atoms, such as a methyl group, are mentioned. Furthermore, some or all of the hydrogen atoms of these hydrocarbon groups may be substituted with deuterium atoms.

Among the groups represented by Y ¹ and Y ² , specific examples of the amino group include an amino group (—NH ₂ group), and an alkylamino group such as a methylamino group and a diethylamino group, such as diphenyl. An arylamino group such as an amino group can be mentioned.

Of the groups represented by Y ¹ and Y ² , the silyl group specifically includes a silyl group (—SiH ₃ group), and an alkylsilyl group such as a trimethylsilyl group, such as a triphenylsilyl group. And arylsilyl group.

Among these groups represented by Y ¹ and Y ² , a hydrocarbon group having 1 to 20 carbon atoms is preferable, a hydrocarbon group having 1 to 20 carbon atoms substituted with a halogen atom is more preferable, and a halogen atom is substituted. An alkyl group having 1 to 20 carbon atoms is more preferable.

  Z in the general formula (1) represents a hydrogen atom or a deuterium atom. Z is preferably a deuterium atom. The deuterated complex in which Z is a deuterium atom can be obtained by mixing a complex in which Z in the general formula (1) is a hydrogen atom with a deuterating agent and performing a deuterium substitution reaction. Examples of the deuterating agent used include protic compounds containing deuterium, specifically, deuterated alcohols such as deuterated water, deuterated methanol, and deuterated ethanol, deuterated hydrogen chloride, and deuterated alkali. It is done. In order to promote the deuteration reaction, a base agent or additive such as trimethylamine or triethylamine may be added to the reaction solution. By performing deuterium substitution in this way, deactivation of electrons due to vibration of the C—H bond is suppressed, and a complex with a higher emission quantum yield can be obtained.

  The strong light-emitting rare earth complex of the present invention can also be polymerized as required by polymerizing the rare earth complex of the general formula (1) where Y is an alkenyl group.

  The rare earth complex represented by the general formula (1), in particular, a complex in which Ln is any one of Eu, Tb, Yb, Nd, Er, Sm, Dy, and Ce shows a sharp emission spectrum. Such a complex has laser oscillation conditions, and a thin film formed by introducing this complex into a transparent matrix such as a resin or an inorganic material can be applied to a laser oscillation device or the like.

  The rare earth complex represented by the general formula (1) is prepared, for example, as described in JP-A-2003-81986, after the rare earth complex hydrate is produced, the hydrate and the following general formula ( It can be obtained by reacting the phosphine oxides of 2).

（式中、Ｒ¹〜Ｒ¹⁸，ａ，ｂ，ｃは前記一般式（１）中と同様の意味を示す。）

(In the formula, R ^{1 to} R ¹⁸ , a, b, and c have the same meaning as in general formula (1).)

  The phosphine oxides represented by the general formula (2) can be obtained by reacting iminophosphoranes with phosphorus oxytrichloride. For example, the method described in JP-A No. 2000-355595 has a high yield. It is advantageous to obtain high purity phosphine oxides at a high rate.

  A laser oscillation device using a strong light-emitting rare earth complex according to the present invention includes a laser oscillation unit, which is mounted on a substrate and is formed of a thin film in which the rare earth complex of the present invention is introduced into a transparent matrix, and the laser oscillation unit On the other hand, light irradiation means for irradiating excitation light is provided. About the laser oscillation apparatus using the rare earth complex containing thin film, the structure similar to the apparatus of Unexamined-Japanese-Patent No. 2004-179296 can be taken, for example. Specifically, for example, reflecting mirrors are provided at both ends of a thin film placed on a substrate, and excitation light is generated in a linear portion by irradiating excitation light in a linear manner using light irradiation means. Amplify and perform laser oscillation. Alternatively, laser oscillation may be performed by irradiating excitation light to a thin film formed into a linear waveguide shape by light irradiation means and amplifying the oscillation light in the waveguide.

  The transparent matrix into which the rare earth complex is introduced has only to be transparent so that the excitation light is sufficiently transmitted, and is preferably a transparent resin, a transparent inorganic material, or a transparent organic-inorganic hybrid material. As the transparent resin, polyimide, polyamide, polymethyl methacrylate, polyacrylate, polyester, polyurethane, polycarbonate, epoxy resin, polystyrene, siloxane polymer, halides or deuterides thereof, and a resin in which two or more of these are mixed are preferable. As the transparent inorganic material, glass produced by a sol-gel method is preferable. In the case where a resin having photosensitivity is used as the transparent matrix, patterning can be directly performed on the thin film by photolithography, and the pattern forming process can be reduced.

As the light irradiation means, an LED, deuterium or xenon, a halogen lamp, a laser, or the like is used. For example, since the europium (Eu) complex has absorption bands derived from the ligand of the complex in the vicinity of 350 nm and absorption bands corresponding to the Eu ³⁺ f-f transition in the vicinity of 395 nm and 465 nm, such a wavelength. By using an excitation means that emits light, the europium complex can be excited and oscillated.

  The rare earth complex of the present invention represented by the general formula (1) has very high compatibility with a transparent matrix, particularly a transparent resin. For example, the europium (Eu) complex represented by the chemical formula (3) can be mixed in an acrylic resin, a polystyrene resin, or the like at a high concentration.

Note that, by varying the substituents ^R 1 ^{to R 18} and ^Y 1, ^{Y 2} types of general formula (1), it is possible to appropriately vary the compatibility with the transparent matrix. Since the fact that a complex having a high concentration can be mixed in the matrix means that higher intensity light emission can be easily obtained, the rare earth complex of the present invention is used as a laser material. Very useful.

  In addition, what mixed the rare earth complex based on this invention in either resin, a transparent inorganic material, or a transparent organic-inorganic hybrid material is used as optical functional materials, such as a light-emitting body light-emitted by the excitation light from the outside. it can.

  It is also possible to produce a molded body of a predetermined shape using a matrix mixed with the rare earth complex according to the present invention, and to produce a light emitting device or the like by combining it with an excitation light source such as an LED. In such applications, the matrix does not have to be transparent, and a translucent one can also be used.

  The present invention will be described in detail by the following examples, but the present invention is not limited only to these examples.

  In the examples and comparative examples, the hexafluoroacetylacetonate group is abbreviated as hfa, tris [tris (dimethylamino) phosphoranylideneamino] phosphine oxide is abbreviated as PZO, and triphenylphosphine oxide is abbreviated as TPPO.

Eu (hfa) ₃ (H ₂ O) ₂ complex and Eu (hfa) ₃ (TPPO) ₂ complex were synthesized according to the method described in Examples of Japanese Patent Application Laid-Open No. 2003-81986.

Example 1 Synthesis of Eu (hfa) ₃ (PZO) Complex (Compound (3) below)

A methanol solution of 0.72 g (1.2 mmol) of PZO was added dropwise to a methanol solution of 0.49 g (0.62 mmol) of Eu (hfa) ₃ (H ₂ O) ₂ complex, followed by stirring at room temperature for 2 hours. . A white precipitate gradually formed during the reaction. After completion of the reaction, the white precipitate was filtered and washed, and then dried overnight at room temperature to obtain Eu (hfa) ₃ (PZO) complex as a white solid.

The elemental analysis values of this white solid are C: 29.18%, H: 4.50%, N: 12.30%, and the calculated value of Eu (hfa) ₃ (PZO) complex is C: 29. It was in good agreement with 26%, H: 4.17%, and N: 12.41%.

(Example 2 and Comparative Example 1-2)
Eu (hfa) ₃ (PZO) complex (Example 2), Eu (hfa) ₃ (H ₂ O) ₂ complex (Comparative Example 1) and Eu (hfa) ₃ (TPPO) ₂ (Comparative Example 2) in THF The emission spectrum of was measured. The measurement used HITACHI F-4500. All complex concentrations were measured at 2 × 10 ⁻⁵ M.

The measurement results of the emission spectra of the three types of complexes are shown in FIG. All, Eu (III) to be seen band derived from characteristic 4f-4f transitions, a spectrum having a maximum at around ^{_{(5 D 0 → 7 F 2}} ) 615nm was obtained. In the Eu (hfa) ₃ (PZO) complex that is the complex of the present invention, excitation light is used compared to the Eu (hfa) ₃ (H ₂ O) ₂ complex and Eu (hfa) ₃ (TPPO) ₂ complex that are the prior art. Despite a small light absorption at 320 nm (see FIG. 2), the emission intensity at 615 nm increased by about 40% or more.

Further, the obtained Eu (hfa) ₃ (PZO) complex powder emits red light not only by excitation by black light irradiation (longer wavelength) but also by purple LED light irradiation (for example, 380 nm) or blue LED light irradiation (for example, 430 nm). Indicates.

  By introducing the strongly luminescent rare earth complex of the present invention into a matrix, it can be used for a laser oscillation device, an optical functional material, a light emitting device, and the like.

It is a figure which shows the emission spectrum of the Eu (III) complex which becomes this invention and a prior art. It is a figure which shows the absorption spectrum of the Eu (III) complex which becomes this invention and a prior art.

Claims (9)

A strongly luminescent rare earth complex represented by the following general formula (1).

(In the formula, Ln represents a rare earth atom. A, b and c are each a positive integer of 3 or less or 0, but they are not all 0 simultaneously. R ^{1 to} R ¹⁸ may be the same or different. Well, it represents a hydrocarbon group having 1 to 10 carbon atoms, and R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ , R ⁹ and R ¹⁰ , R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁷ and R ¹⁸ may be bonded to each other to form a ring structure, n is an integer of 1 to 5. Y ¹ and Y ² are The same or different hydrocarbon group having 1 to 20 carbon atoms, amino group, hydroxyl group, nitro group, sulfonic acid group, cyano group, silyl group, phosphonic acid group, diazo group or mercapto group, Z represents a hydrogen atom. Or represents a deuterium atom.)   The strongly luminescent rare earth complex according to claim 1, wherein Ln in the general formula (1) is any one of Eu, Tb, Yb, Nd, Er, Sm, Dy, and Ce. 3. The strongly luminescent rare earth complex according to claim ¹ , wherein R ^{1 to} R ¹⁸ in the general formula (1) are all methyl groups.   The strongly luminescent rare earth complex according to any one of claims 1 to 3, wherein a, b and c in the general formula (1) are all 1.   A laser oscillation part comprising a thin film in which a strong light-emitting rare earth complex according to any one of claims 1 to 4 is placed on a substrate, and excitation light for the laser oscillation part. And an irradiating means for irradiating the laser.   6. The laser oscillation device according to claim 5, wherein the transparent matrix is any one of a transparent resin, a transparent inorganic material, and a transparent organic-inorganic hybrid material.   Transparent resin is any of polyimide, polyamide, polymethyl methacrylate, polyacrylate, polyester, polyurethane, polycarbonate, epoxy resin, polystyrene, siloxane polymer, halides or deuterides thereof, or a mixture of two or more of these. The laser oscillation apparatus according to claim 6, wherein:   5. An optical functional material comprising any one of a resin, a transparent inorganic material, and a transparent organic-inorganic hybrid material mixed with the strong light-emitting rare earth complex according to any one of claims 1 to 4.   A light emitting device comprising: a molded body containing the strongly luminescent rare earth complex according to any one of claims 1 to 4; and an excitation light source.

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