JP3687791B2 - Novel rare earth complexes with circularly polarized light emission - Google Patents

Description

  The present invention relates to a novel rare earth complex having circularly polarized light emission.

Since the rare earth complex is a light emitter that has high color purity and is stable with respect to excitation, for example, a luminescent ink (see, for example, Patent Document 1) and an organic electroluminescence element (see, for example, Patent Document 2). Is suitably used. Among these, as a rare earth complex having circularly polarized light emission property, for example, tris (3-trifluoroacetylcamphorato) europium is known (for example, see Non-Patent Document 1). Here, the circularly polarized light-emitting property represents a property that, for example, in a compound that emits fluorescence or phosphorescence by irradiation with ultraviolet rays or the like, the intensity of the circularly polarized light on the left and right of the fluorescence or phosphorescence emitted by the compound is different. That is, the intensity of the right circularly polarized component of the emitted fluorescence or phosphorescence and I _R, the intensity of left-handed circularly polarized light component and I _L, the following equation

で表されるｇ値を定義したとき、ｇ≠０となる光を放射する性質である。

When the g value represented by is defined, it is a property of emitting light satisfying g ≠ 0.

  Such a circularly polarized light-emitting compound can effectively use emitted light when used in, for example, an organic electroluminescence device (see, for example, Patent Document 3). However, for example, known rare earth complexes such as tris (3-trifluoroacetylcamphorato) europium have insufficient luminescence intensity.

Japanese Patent Publication No.54-22336 JP 2000-204363 A JP 2002-151251 A J. et al. Am. Chem. Soc. , 98 (19), 5858-63 (1976)

  The present invention provides a rare earth complex having extremely high emission intensity and circularly polarized light emission.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a novel rare earth complex, which has been found to have extremely high emission intensity and circularly polarized light emission.

  That is, the present invention relates to the general formula (1)

(In the formula, X ₁ and X ₂ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxyl group having 1 to 4 carbon atoms; Y ₁ , Y ₂ , Y ₃ and Y ₄ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and R ₁ represents an alkyl group having 1 to 8 carbon atoms, a fluorine-substituted alkyl group having 1 to 8 carbon atoms, or a phenyl group. , R ₂ is
(A) a cyclopentadienyl group (one CH ₂ group present in the group may also be replaced by —O— or —S—),
(B) a phenyl group (one or two CH groups present in the group may also be replaced by N),
(C) a naphthyl group (one or two CH groups present in the group may also be replaced by N),
The group (a), (b) and (c) above may be substituted with an alkyl group or a halogen atom, and Ln represents a rare earth metal atom. An optically active rare earth complex represented by

  According to the present invention, it is possible to provide a rare earth complex (1) having a very high emission intensity as compared with a conventional rare earth complex having circularly polarized light emission.

Hereinafter, the present invention will be described in detail.
The optical purity of the compound represented by the general formula (1) of the present invention is preferably 90% or more. Further, X ₁ and X ₂ in the general formula (1) are preferably hydrogen atoms, Y ₁ , Y ₂ , Y ₃ and Y ₄ are preferably hydrogen atoms, and Ln is preferably Eu. .
Moreover, it is preferable that R ₁ is a trifluoromethyl group and R ₂ is a thienyl group.

  As the optically active rare earth complex represented by the general formula (1) (hereinafter referred to as the rare earth complex (1)), the general formula (1-1)

（式中、点線の円弧は一般式（１−１ａ）

(In the formula, the dotted arc represents the general formula (1-1a).

で示される配位子を、実線の円弧は一般式（１−１ｂ）

The solid-line arc is represented by the general formula (1-1b).

で示される配位子を表す。）で表されるR−Δ構造を有する希土類錯体（１）(以下R−Δ希土類錯体（１）と言う。)と、
一般式（１−２）

Represents a ligand represented by And a rare earth complex (1) having an R-Δ structure (hereinafter referred to as R-Δ rare earth complex (1)),
General formula (1-2)

（式中、点線の円弧は一般式（１−１ａ）で示される配位子を、実線の円弧は一般式（１−２ｂ）

(In the formula, the dotted arc represents the ligand represented by the general formula (1-1a), and the solid arc represents the general formula (1-2b).

で示される配位子を表す。）で表されるＳ−Λ構造を有する希土類錯体（１）（以下、Ｓ−Λ希土類錯体（１）と言う。）を挙げることが出来る。
R−Δ構造とＳ−Λ構造は、互いに鏡像異性体の関係にある。

Represents a ligand represented by ) Represented by a rare earth complex (1) (hereinafter referred to as S-Λ rare earth complex (1)).
The R-Δ structure and the S-Λ structure are in an enantiomeric relationship with each other.

Circularly polarized light emission is generally caused by a light-emitting compound having optical activity, and the degree of polarization increases as the optical purity increases. The circularly polarized luminescence, the intensity of the right circularly polarized component of the emitted fluorescence or phosphorescence and I _R, the intensity of left-handed circularly polarized light component and I _L, the following equation

で表されるｇ値を定義したとき、ｇ≠０となる光を放射する性質である。

When the g value represented by is defined, it is a property of emitting light satisfying g ≠ 0.

  Generally, since a rare earth complex has a regular tetragonal prismatic coordination structure, there are two types of stereoisomers with respect to the absolute configuration around the rare earth metal atom. Hereinafter, these two isomers are distinguished by Δ and Λ. Therefore, even if an optically active ligand is introduced into the rare earth complex, an equivalent amount of the two stereoisomers of Δ and Λ are still mixed, so that a compound with high optical purity cannot be obtained.

  Therefore, by introducing a diastereoselective ligand as an optically active ligand, it is possible to obtain a rare earth complex with very high optical purity. And found to have In the present invention, a ligand having diastereoselectivity is a ligand in which two kinds of enantiomers exist (hereinafter represented by R and S), and one of the enantiomers (for example, an R-form ligand). ) Means a ligand having a property that one stereoisomer of the rare earth complex (for example, a Δ rare earth complex) is selectively formed. Ligands with diastereoselectivity may have more than two stereoisomers.

  As a ligand having diastereoselectivity, for example, the following general formula (2)

(Wherein, X ₁ , X ₂ , Y ₁ , Y ₂ , Y ₃ and Y ₄ have the same meaning as in general formula (1)) (hereinafter referred to as ligand (2 ))). Since the ligand (2) has axial asymmetry at the binaphthyl group, there are two optical isomers. Hereinafter, these two isomers are distinguished by R and S. When the ligand (2) is used, for example, the following general formula (3)

(In the formula, X ₁ , X ₂ , Y ₁ , Y ₂ , Y ₃ and Y ₄ represent the same meaning as in general formula (1). R ₃ and R ₄ each independently has 1 to 20 carbon atoms. An alkyl group, a C1-C20 fluorine-substituted alkyl group, a hydroxyl group, a nitro group, an amino group, a sulfonyl group, a cyano group, a silyl group, a phosphonic acid group, a diazo group, a mercapto group, an aryl group, or a heteroaryl group) An optically active rare earth complex represented by the following (hereinafter referred to as rare earth complex (3)) can be obtained. At this time, when the R form was used as the ligand (2), a rare earth complex (3) was selectively produced as a Δ form (hereinafter referred to as R-Δ rare earth complex (3)). Further, when the S form was used as the ligand (2), a Λ form (hereinafter referred to as S-Λ rare earth complex (3)) was selectively produced as the rare earth complex (3).

  The rare earth complex (3) has a circularly polarized light emission property, but considering the light emission intensity, the rare earth complex of the present invention is represented by the following general formula (1).

The compound (rare earth complex (1)) represented by these is preferable. In general formula (1), the substituents represented by X ₁ and X ₂ are each independently a halogen atom such as a hydrogen atom, a fluorine atom or a chlorine atom, or an alkyl such as a methyl group, an ethyl group or an iso-propyl group. Group, and alkoxy groups such as a methoxy group, an ethoxy group, and a tert-butoxy group, and a hydrogen atom is preferable.
In the general formula (1), the substituents represented by Y ₁ , Y ₂ , Y ₃ and Y ₄ are each independently a halogen atom such as a hydrogen atom, a fluorine atom or a chlorine atom, a methyl group, an ethyl group, and An alkyl group such as an iso-propyl group is exemplified, and a hydrogen atom is preferred.

In the general formula (1), examples of the substituent represented by R ₁ include a methyl group, a trifluoromethyl group, a pentafluoroethyl group, a hexafluoro-iso-propyl group, and a perfluorohexyl group. A trifluoromethyl group.
In the general formula (1), examples of the substituent represented by R ₂ include a phenyl group, a tolyl group, a fluorophenyl group, a pentafluorophenyl group, a trifluoromethylphenyl group, a chlorophenyl group, a naphthyl group, a furyl group, a thienyl group, Mention may be made of thianthnyl, pyranyl, isobenzofuranyl, pyrazolyl, pyridyl and pyrazinyl. Furthermore, alkyl group-substituted products, aryl group-substituted products, alkoxy group-substituted products, aryloxy group-substituted products, halogen atom-substituted products, alkoxycarbonyl group-substituted products, nitrile group-substituted products, and nitro group-substituted products of the above groups may be mentioned. Preferably a phenyl group, a tolyl group, a naphthyl group, a furyl group, and a thienyl group, more preferably a thienyl group.

  In the compound of the general formula (1), examples of the rare earth metal represented by Ln include each atom having an atomic number of 57 to 71, preferably Eu or Yb.

  Examples of the method for producing the rare earth complex (1) of the present invention include the following general formula (2) in an organic solvent such as alcohol and acetone.

(Wherein, X ₁ , X ₂ , Y ₁ , Y ₂ , Y ₃ and Y ₄ represent the same meaning as in general formula (1)), and the following general formula (4)

(Wherein, Ln, R ₁ and R ₂ have the same meaning as in formula (1)) are allowed to react with stirring at −50 to 80 ° C., preferably at 0 to 40 ° C. for 1 to 24 hours. The compound of the general formula (2) is, for example, Org. Synth. , Coll. Vol. 8 57 (1993). Moreover, the compound of General formula (4) can be manufactured by the method as described in Japanese Patent Application No. 2003-143292, for example. After completion of the reaction, the solvent is distilled off to obtain the desired rare earth complex (1). If necessary, purification such as recrystallization may be performed.

  When the rare earth complex (1) of the present invention is used as a circularly polarized light emitting material, either one of the two optical isomers of the R-Δ rare earth complex (1) and the S-Λ rare earth complex (1) is used. Although it may be used in an excessively contained state, the optical purity is preferably 90% or more, more preferably 95% or more.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Moreover, a part represents a mass part below.

(Example 1)
2.00 parts of (S) -BINAPO represented by the following formula (5), 2.60 parts of europium-thenoyltrifluoroacetonate complex represented by the following formula (6), and 75 parts of methanol were stirred at room temperature for 2 hours. And reacted. After completion of the reaction, the solvent was distilled off with an evaporator to obtain a light yellow powder. This was recrystallized from ethanol to obtain 2.91 parts of a rare earth complex represented by the following formula (7) (S-Λ body; hereinafter referred to as S-Λ rare earth complex (7)).

以下の方法で式（７）で表される希土類錯体が生成していることを確認した。
^１Ｈ ＮＭＲ（ｄ_６−Ａｃｅｔｏｎｅ） δ ５．１２（ｓ）， ６．４４（ｓ）， ６．７１（ｔ）， ６．８９（ｔ）， ７．１８（ｑ）， ７．２３（ｔ）， ７．３０（ｔ）， ７．６３（ｔ）， ７．７６（ｔ）， ７．８９（ｍ）， ８．０５（ｍ）， ８．３１（ｔ）
^３１Ｐ ＮＭＲ（ｄ_６−Ａｃｅｔｏｎｅ） δ −６７．４７（ｓ）
元素分析 測定値 Ｃ５７．１９％ Ｈ３．７１％ Ｅｕ１０．４％
計算値 Ｃ５５．５５％ Ｈ３．０２％ Ｅｕ１０．３％

It was confirmed that the rare earth complex represented by the formula (7) was generated by the following method.
¹ H NMR (d ₆ -acetone) δ 5.12 (s), 6.44 (s), 6.71 (t), 6.89 (t), 7.18 (q), 7.23 (t ), 7.30 (t), 7.63 (t), 7.76 (t), 7.89 (m), 8.05 (m), 8.31 (t)
³¹ P NMR (d ₆ -acetone) δ −67.47 (s)
Elemental analysis Measured value C57.19% H3.71% Eu10.4%
Calculated value C55.55% H3.02% Eu10.3%

(Example 2)
1.98 parts of (S) -BINAPO, 2.56 parts of europium-benzoyltrifluoroacetonate complex represented by the following formula (8), and 70 parts of methanol were reacted at room temperature for 2 hours with stirring. After completion of the reaction, the solvent was distilled off with an evaporator to obtain a light yellow powder. This was recrystallized from ethanol to obtain 2.12 parts of a rare earth complex represented by the following formula (9) (S-Λ form; hereinafter referred to as S-Λ rare earth complex (9)).

It confirmed that the rare earth complex represented by Formula (9) was producing | generating with the following method.
¹ H NMR (d ₆ -acetone) δ 5.56 (s), 6.42 (s), 6.91 (t), 7.13 (m), 7.25 (d), 7.36 (t ), 7.64 (s), 7.75 (t), 7.93 (m), 7.99-8.14 (m)
³¹ P NMR (d ₆ -acetone) δ −62.55 (s)
Elemental analysis Measured value C60.92% H3.96% Eu10.3%
Calculated C61.21% H3.47% Eu10.5%

(Example 3)
1.99 parts of (S) -BINAPO, 3.00 parts of europium-naphthoyltrifluoroacetonate complex represented by the following formula (10), and 70 parts of acetone were reacted by stirring at room temperature for 2 hours. After completion of the reaction, the solvent was distilled off with an evaporator to obtain a light yellow powder. This was recrystallized from ethanol to obtain 2.12 parts of a rare earth complex represented by the following formula (11) (S-Λ form; hereinafter referred to as S-Λ rare earth complex (11)).

It was confirmed that the rare earth complex represented by the formula (11) was generated by the following method.
¹ H NMR (d ₆ -acetone) δ 5.91 (s), 6.44 (s), 6.87 (t), 7.07 (m), 7.13-7.29 (m), 7 .42-7.47 (m), 7.61 (t), 7.76 (t), 7.94 (m), 8.01-8.22 (m)
³¹ P NMR (d ₆ -acetone) δ −64.25 (s)
Elemental analysis Measured value C63.74% H3.51% Eu9.4%
Calculated C63.05% H3.69% Eu9.3%

(Example 4)
2.00 parts of (S) -BINAPO, 2.68 parts of ytterbium-thenoyltrifluoroacetonate complex represented by the following formula (12), and 50 parts of acetone were reacted by stirring at room temperature for 2 hours. After completion of the reaction, the solvent was distilled off with an evaporator to obtain a light yellow powder. This was recrystallized from ethanol to obtain 1.27 parts of a rare earth complex represented by the following formula (13) (S-Λ form; hereinafter referred to as S-Λ rare earth complex (13)).

It was confirmed that the rare earth complex represented by the formula (11) was generated by the following method.
Elemental analysis Measured value C53.01% H3.70% Yb11.4%
Calculated C53.48% H3.17% Yb 11.3%

(Example 5)
In Example 4, the ytterbium-benzoyltrifluoroacetonate complex represented by the following formula (14) is used in place of the complex represented by the formula (12), whereby the rare earth complex represented by the following formula (15) is used. 2.14 parts of (S-Λ body; hereinafter referred to as S-Λ rare earth complex (15)) were obtained.

(Example 6)
In Example 4, the ytterbium-naphthoyltrifluoroacetonate complex represented by the following formula (16) is used in place of the complex represented by the formula (12), whereby the rare earth represented by the following formula (17) is used. 1.88 parts of a complex (S-Λ form; hereinafter referred to as S-Λ rare earth complex (17)) was obtained.

(Examples 7 to 12)
In Examples 1 to 6, by using (R) -BINAPO instead of (S) -BINAPO, R-Δ rare earth complexes (7), (9), (11), (13), (15), (17) was obtained.

(Comparative Example 1)
According to the method described in JP-A-2003-327590, a rare earth complex (S-Λ form; hereinafter referred to as S-Λ) represented by the following formula (18) from (S) -BINAPO and an ytterbium-hexafluoroacetylacetonate complex Rare earth complex (18) ”was obtained.

(Evaluation example 1)
(Measurement of circularly polarized light emission characteristics)
0.1 parts of S-Λ rare earth complex (7) and S-Λ rare earth complex (9) were dissolved in 1 part of acetone, and circularly polarized light emission characteristics were measured using CPL-200 manufactured by JASCO Corporation. . The g values were -0.04 and -0.08 for emitted light having a wavelength of 590 nm, respectively.

(Evaluation example 2)
(Emission evaluation)
0.1 parts of each of S-Λ rare earth complex (7) and S-Λ rare earth complex (9) of the present invention and comparative compound: tris (3-trifluoroacetylcamphorato) europium (manufactured by Aldrich) A solution dissolved in 5 parts of acetone was prepared. This solution was irradiated with ultraviolet light (about 365 nm) by a black light lamp. The solution of the S-Λ rare earth complex (7) and the S-Λ rare earth complex (9) of the present invention emitted strong red light, whereas the tris (3-trifluoroacetylcamphorato) europium solution emitted very weak light. Not observed.

The fluorescence emission intensities of the prepared solutions were compared using Hitachi F-4000. The emission intensity when excited at a wavelength of 410 nm is shown in FIG. There was a large difference in emission intensity between the optically active rare earth complex of the present invention and the comparative compound: tris (3-trifluoroacetylcamphorato) europium.

(Evaluation example 3)
In the same manner as in Evaluation Example 2, a solution was prepared by dissolving 0.1 part of each of the S-Λ rare earth complex (13) of the present invention and the comparative compound: S-Λ rare earth complex (18) in 5 parts of acetone. did. Since both emitted light in a wavelength region of 900 nm or more (infrared region), the fluorescence emission intensities of the solutions were compared using a SPEX Fluorolog-3 system corresponding to the measurement of the wavelength region. FIG. 2 shows the emission intensity when excited with the wavelength at which the excitation spectrum becomes maximum (S-Λ rare earth complex (13) of the present invention: 405 nm, S-Λ rare earth complex (18): 366 nm). The optically active rare earth complex of the present invention had higher emission intensity than the comparative compound: S-Λ rare earth complex (18).

  The rare earth complex having circularly polarized light emission property of the present invention has high color purity, very high emission intensity, and can effectively use emitted light, and thus is suitably used for light emitting inks and organic electroluminescence elements.

Fluorescence emission spectra of S-Λ rare earth complex (7), S-Λ rare earth complex (9) and comparative compound: tris (3-trifluoroacetylcamphorato) europium (manufactured by Aldrich), comparatively measured in Evaluation Example 2. FIG.

FIG. 6 is a fluorescence emission spectrum diagram of S-Λ rare earth complex (13) and a comparative compound: S-Λ rare earth complex (18), which were comparatively measured in Evaluation Example 3.

Claims (7)

General formula (1)

(In the formula, X ₁ and X ₂ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxyl group having 1 to 4 carbon atoms; Y ₁ , Y ₂ , Y ₃ and Y ₄ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and R ₁ represents an alkyl group having 1 to 8 carbon atoms, a fluorine-substituted alkyl group having 1 to 8 carbon atoms, or a phenyl group. , R ₂ is
(A) a cyclopentadienyl group (one CH ₂ group present in the group may also be replaced by —O— or —S—),
(B) a phenyl group (one or two CH groups present in the group may also be replaced by N),
(C) a naphthyl group (one or two CH groups present in the group may also be replaced by N),
The group (a), (b) and (c) above may be substituted with an alkyl group or a halogen atom, and Ln represents a rare earth metal atom. An optically active rare earth complex represented by: The optically active rare earth complex according to claim 1, wherein X ₁ and X ₂ in the general formula (1) are hydrogen atoms. The optically active rare earth complex according to claim ₁ , wherein Y ₁ , Y ₂ , Y ₃ and Y ₄ in the general formula (1) are hydrogen atoms. The optically active rare earth complex according to claim 1, wherein Ln in the general formula (1) is Eu or Yb. Optically active rare earth complex according to any one of claims 1 to 4 R ₁ is a trifluoromethyl group in the general formula (1). Optically active rare earth complex according to any one of claims 1 to 5 R ₂ is a thienyl group in the general formula (1). The optically active rare earth complex according to any one of claims 1 to 6, wherein the compound represented by the general formula (1) has an optical purity of 90% or more.

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