JP2012188357A - Metal complex, light-emitting device, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal complex exhibiting luminescence, and capable of being excited by a lower energy than conventional metal complexes.SOLUTION: The metal complex is a cyclometalated complex represented by formula (1) or (2). [(M)(L)(L)]... (1). [(M)(M)(M')(L)(L)]...(2). In the formulae, Mdenotes Ptor Pd; Mdenotes H; M'denotes H, Au, Ag, Cu, Hg, Tlor Pb; L, Land Ldenote an anion of a pyrazole derivative; and Land Lchelate-coordinate to M.

Description

  The present invention relates to a metal complex (in particular, a cyclometalated complex) exhibiting luminescence. The present invention also provides a light-emitting element and a display device including the metal complex.

  In organic EL (electroluminescence) elements for display devices, conventionally, light emission from a singlet excited state (that is, fluorescence) has been used. In this case, the luminous efficiency of 25% was the maximum, and the luminous efficiency was very poor. Thus, as a method for increasing the light emission efficiency, it has been proposed to use light emission (that is, phosphorescence) from a triplet excited state. When phosphorescence is used, 100% light emission efficiency is possible in principle.

  It has been reported that a metal complex obtained by cyclometalating phenylpyridine with iridium generates phosphorescence with high efficiency even at room temperature. Since then, most researches on phosphorescent materials have been conducted on iridium complexes, and the evaluation of the potential of other metal complexes as light-emitting elements has not yet been made sufficiently.

  The inventors of the present invention tried to synthesize a mixed metal complex using 3,5-dimethylpyrazole, and succeeded in isolating a metal complex that showed very strong light emission when irradiated with ultraviolet light. As a result of the luminescence measurement of this metal complex, the mixed metal complex containing Pt and silver exhibits phosphorescent blue luminescence, and the luminescence quantum yield in the solid state and in solution is 0.85 and 0.51, respectively. It was found to be higher than the phenylpyridine-iridium complex. The light emission characteristics of this metal complex are not inferior to the materials having the best light emission characteristics among the compounds known to date as light emitting materials for organic EL devices.

  In addition, the present inventors have synthesized a series of mixed metal complexes using pyrazoles having various substituents, and have developed some metal complexes having a high solid-state quantum yield (for example, patents). Reference 1).

JP 2008-81401 A

  In the field of organic EL devices, metal complexes that can be excited with low energy are required. The present invention has been made paying attention to such circumstances, and its object is to provide a metal complex that exhibits luminescence and can be excited at a lower energy than a mixed metal complex in which a conventional pyrazolate is crosslinked. In other words, the object is to provide a metal complex that exhibits luminescence and has a light absorption band shifted to a longer wavelength side than a light absorption band (about 250 to 350 nm) of a conventional mixed metal complex in which pyrazolate is crosslinked. And

  Under the idea that the excitation energy can be reduced if the minimum vacant orbital (LUMO) is reduced by extending the π-conjugated system of the metal complex, the present inventors have conducted intensive studies, and as a result, It has been found that a metalated complex can achieve the above object. The present invention based on such knowledge is as follows.

[1] Formula (1):
[(M ^II ) ₂ (L ¹ ) ₂ (L ² ) ₂ ] (1)
[In formula (1), M ^II represents Pt ^II or Pd ^II .
L ¹ is a formula (L-1):

{In Formula (L-1), R ^{1 to} R ⁶ each independently represents a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. R ³ and R ⁴ or R ⁴ and R ⁵ are bonded to form a condensed aromatic hydrocarbon ring which may have a substituent together with the benzene ring. }
The monovalent anionic ligand represented by these is shown.
L ² represents the formula (L-2):

{In Formula (L-2), R ^{7 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Show. }
The monovalent anionic ligand represented by these is shown. ]
And L ¹ is chelate-coordinated to M ^II with the N atom of the pyrazole ring and the C atom of the benzene ring.
[2] Formula (2):
[(M ^II ) ₂ (M ^I ) (M ′ ^I ) (L ³ ) (L ² ) ₄ ] (2)
[In the formula (2), M ^II represents Pt ^II or Pd ^II .
M ^I represents H ⁺ .
M ′ ^I represents H ⁺ , Au ^I , Ag ^I , Cu ^I , Hg ^I , Tl ^I or Pb ^I.
L ³ represents formula (L-3):

{In Formula (L-3), R ^{1 to} R ⁶ each independently represents a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. R ³ and R ⁴ or R ⁴ and R ⁵ are bonded to form a condensed aromatic hydrocarbon ring which may have a substituent together with the benzene ring. }
The bivalent anionic ligand represented by these is shown.
L ² represents the formula (L-2):

{In Formula (L-2), R ^{7 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Show. }
The ligand represented by these is shown. ]
And L ³ is chelate-coordinated to M ^II by the N atom of the pyrazole ring and the C atom of the benzene ring.
[3] The cyclometalated complex according to the above [1] or [2], wherein M ^II is Pt ^II .
[4] The cyclometalated complex according to any one of [1] to [3], wherein R ⁶ is a hydrogen atom or a halogen atom.
[5] The cyclometalated complex according to any one of the above [1] to [4], wherein R ¹ , R ⁷ and R ⁹ are phenyl groups which may have a substituent.
[6] A light emitting device having a light emitting layer containing the cyclometalated complex according to any one of [1] to [5].
[7] A display device having the light emitting device according to [6].

  Hereinafter, the “cyclometalated complex represented by the formula (1)” may be abbreviated as “cyclometalated complex (1)”. Similarly, ligands represented by other formulas may be abbreviated as well.

  The light absorption band of the cyclometalated complex of the present invention is shifted to a longer wavelength side than a mixed metal complex in which a conventional pyrazolate is crosslinked, and is excited at a lower energy than a mixed metal complex in which a conventional pyrazolate is crosslinked. be able to.

It is a schematic cross section which shows an example of the light emitting element of this invention. 2 is an ORTEP diagram showing the structure of the cyclometalated complex of Example 1. FIG. It is an ultraviolet visible absorption spectrum of the dichloromethane solution of the cyclometalated complex of Example 1 (complex concentration: 5.24 × 10 ⁻⁶ M, 1.05 × 10 ⁻⁵ M, 1.57 × 10 ⁻⁵ M, 2 .10 × 10 ⁻⁵ M and 5.24 × 10 ⁻⁵ M). It is the emission spectrum of the solid state of the cyclometalated complex of Example 1 (wavelength of excitation light: 355 nm, measurement temperature: 298 K). It is the emission spectrum of the solid state of the cyclometalation complex of Example 1 in 80K, 150K, 220K, and 298K (wavelength of excitation light: 355 nm). 4 is an ORTEP diagram showing the structure of the cyclometalated complex of Example 2. FIG. It is an ultraviolet visible absorption spectrum of the dichloromethane solution of the cyclometalated complex of Example 2 (complex concentration: 5.03 × 10 ⁻⁶ M, 1.01 × 10 ⁻⁵ M, 1.51 × 10 ⁻⁵ M, 2 .01 × 10 ⁻⁵ M and 5.03 × 10 ⁻⁵ M). It is an emission spectrum of the solid state of the cyclometalated complex of Example 2 (wavelength of excitation light: 355 nm, measurement temperature: 298 K). It is the emission spectrum of the solid state of the cyclometalation complex of Example 2 in 80K, 150K, 220K, and 298K (wavelength of excitation light: 355 nm). 4 is an ORTEP diagram showing the structure of the cyclometalated complex of Example 3. FIG. It is an ultraviolet visible absorption spectrum of the dichloromethane solution of the cyclometalated complex of Example 3 (complex concentration: 4.92 × 10 ⁻⁶ M, 9.84 × 10 ⁻⁶ M, 1.48 × 10 ⁻⁵ M, 1 97 × 10 ⁻⁵ M and 4.92 × 10 ⁻⁵ M). It is an emission spectrum of the solid state of the cyclometalated complex of Example 3 (wavelength of excitation light: 355 nm, measurement temperature: 298 K). It is the emission spectrum of the solid state of the cyclometalated complex of Example 3 in 80K, 150K, and 298K (wavelength of excitation light: 355 nm). 4 is an ORTEP diagram showing the structure of the cyclometalated complex of Example 4. FIG. It is an ultraviolet visible absorption spectrum of the dichloromethane solution of the cyclometalated complex of Example 4 (complex concentration: 4.99 × 10 ⁻⁶ M, 9.98 × 10 ⁻⁵ M, 1.50 × 10 ⁻⁵ M, 2 0.000 × 10 ⁻⁵ M and 4.99 × 10 ⁻⁵ M). It is the emission spectrum of the solid state of the cyclometalated complex of Example 4 (wavelength of excitation light: 355 nm, measurement temperature: 298 K). It is the emission spectrum of the solid state of the cyclometalated complex of Example 4 in 80K, 150K, 220K, and 298K (wavelength of excitation light: 355 nm).

The cyclometalated complex (1) of the present invention is a cyclometalated complex in which L ¹ is chelate-coordinated to M ^II by the N atom of the pyrazole ring and the C atom of the benzene ring, and the cyclometalated complex (2) Is a cyclometalated complex in which L ³ is chelate coordinated to M ^II by the N atom of the pyrazole ring and the C atom of the benzene ring. Here, the cyclometalated complex means a metal complex having a cyclic structure containing at least one metal-carbon bond, and the structure of the cyclometalated portion of the cyclometalated complexes (1) and (2) has the formula It is represented by (1C) and (2C).

A common feature of the cyclometalated complexes (1) and (2) of the present invention is that both are cyclometalated complexes. By cyclometallation, the pyrazole ring and the benzene ring are almost on the same plane, and the π-conjugated system is expanded, so that the LUMO of the cyclometalated complex of the present invention is lowered. As a result, the cyclometalated complex of the present invention can be excited with low energy. Whether or not the metal complex is a cyclometallated complex can be confirmed by X-ray crystal structure analysis. Also, by checking the presence or absence of binding of M ^II and C atoms of the benzene ring using ¹³ C NMR, it can be confirmed whether the cyclometallated complex.

Furthermore, the cyclometalated complexes (1) and (2) of the present invention have a common feature that none of them has a counter anion such as PF ₆ ⁻ . The cyclometalated complexes (1) and (2) of the present invention having no counter anion are molecular metal complexes, and are more easily sublimated than ionic metal complexes having a counter anion. Have.

  Hereinafter, the cyclometalated complexes (1) and (2) of the present invention will be described in order. In addition, in Formula (1), Formula (2), etc., the same symbol represents the same meaning and the description is also the same.

M ^II represents Pt ^II or Pd ^II , preferably Pt ^II .
M ^I represents H ⁺ . M ′ ^I represents H ⁺ , Au ^I , Ag ^I , Cu ^I , Hg ^I , Tl ^I or Pb ^I , preferably H ⁺ , Au ^I , Ag ^I or Cu ^I , more preferably H ⁺ , Au ^I. Or Ag ^I.

L ¹ is a monovalent anionic ligand represented by the formula (L-1). In Formula (L-1), R ^{1 to} R ⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Alternatively, R ³ and R ⁴ or R ⁴ and R ⁵ are combined to form a condensed aromatic hydrocarbon ring which may have a substituent together with the benzene ring.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The alkyl group may be linear, branched or cyclic. Examples of the substituent that the alkyl group may have include the above-described halogen atoms. Examples of the alkyl group which may have a substituent include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, an i-butyl group, a t-butyl group, a pentyl group, a hexyl group and a cyclohexyl group. Group, heptyl group, octyl group, ethylhexyl group, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorohexyl group and the like. The number of carbon atoms in the alkyl group of R ¹ to R ⁶ is preferably 1 to 8, more preferably 1-4.

The aryl group may be either an aromatic hydrocarbon group (eg, phenyl group, naphthyl group, anthryl group) or a heteroaromatic hydrocarbon group (eg, pyridyl group), preferably an aromatic hydrocarbon group. The aryl group of R ^{1 to} R ⁶ is preferably 6 to 14 members, more preferably 6 to 10 members. Examples of the substituent that the aryl group may have include the above-described halogen atom or an alkyl group that may have a substituent.

In the formula (L-1), R ³ and R ⁴ or R ⁴ and R ⁵ are bonded, preferably R ⁴ and R ⁵ are bonded, and together with the benzene ring, an optionally substituted group An aromatic hydrocarbon ring may be formed. Examples of the condensed aromatic hydrocarbon ring include a naphthalene ring, a phenanthrene ring, and an anthracene ring.

L ³ is a ligand represented by the formula (L-3). Here, the ligand (L-3) is a divalent anionic ligand obtained by dissociating a hydrogen ion from the N atom at the 1-position of the pyrazole ring of the above-described ligand (L-1). is there. Therefore, the description of R ^{1 to} R ⁶ in Formula (L-3) is the same as that described above in Formula (L-1).

L ² is a ligand represented by the formula (L-2). The ligand (L-2) is a monovalent anionic ligand obtained by dissociating a hydrogen ion from the N atom at the 1-position of the compound represented by the formula (L-4).

In Formula (L-2), R ^{7 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. . The explanation of the halogen atom of R ^{7 to} R ^9, the optionally substituted alkyl group and the optionally substituted aryl group is the same as described above for R ^{1 and the} like.

In order to form the cyclometalated complexes (1) and (2) of the present invention, it is preferable that the steric hindrance of R ⁶ is small in the formulas (L-1) and (L-3). Accordingly, R ⁶ is preferably a hydrogen atom or a halogen atom, and more preferably a hydrogen atom.

In formula (L-1), formula (L-2) and formula (L-3), R ¹ , R ⁷ and R ⁹ are preferably a phenyl group which may have a substituent. Examples of the substituent which the phenyl group may have include the above-described halogen atom or an alkyl group which may have a substituent. Furthermore, L ¹ is more preferably a monovalent anionic ligand represented by the formula (L-1a), and L ² is more preferably a monovalent anion represented by the formula (L-2a). An anionic ligand, L ³ is more preferably a divalent anionic ligand represented by the formula (L-3a).

Next, the manufacturing method of the cyclometalation complex of this invention is demonstrated. First, a metal complex represented by the formula (11) is obtained by heating and refluxing 1 equivalent of the metal complex represented by the formula (3) and about 3 equivalents of KOH in acetonitrile under an argon atmosphere. This metal complex (11) is one type of cyclometalated complex (1), and L ^{2 in} formula (1) corresponds to L ²¹ in formula (11). That is, the metal complex (11) is one type of cyclometalated complex (1) in which the basic skeletons of L ¹ and L ² are the same.

In the metal complex (11), L ²¹ not in M ^II and cyclometallated, compared with L ¹ that M ^II and cyclometallated, since bonding force between the M ^II is weak, substitution with other ligands can do. Therefore, by replacing L ²¹ of the metal complex (11) with L ^2, it is possible to produce various cyclometallated complex (1).

Moreover, the metal complex represented by Formula (21) is obtained by refluxing 1 equivalent of the metal complex represented by Formula (3) and about 1 equivalent of KOH in acetonitrile under an argon atmosphere. This metal complex (21) is a kind of cyclometalated complex (2), L ^{2 in} formula (2) corresponds to L ²¹ in formula (21), and M ^I and M ′ ^I are H ⁺ . is there. That is, the metal complex (21) is ^one of the cyclometalated complexes (2) in which the basic skeletons of L ¹ and L ² are the same and M ^I and M ′ ^I are H ⁺ .

In the metal complex (21), L ²¹ which is not M ^II and cyclometallated, compared with M ^II and cyclometallated L ^3, since bonding force between the M ^II is weak, substitution with other ligands can do. Therefore, a cyclometalated complex (2) in which M ^I and M ′ ^I are H ⁺ can be produced by replacing L ²¹ of the metal complex (21) with L ² . Further, M ′ ^I can be exchanged for Au ^I , Ag ^I , Cu ^I , Hg ^I , Tl ^I or Pb ^I by a known method.

  The metal complex (3), which is a starting material for the above-described methods for producing the cyclometalated complexes (1) and (2), can be produced according to a known method, for example, according to the method described in WO 2006/101276. it can.

  Next, the use of the cyclometalated complex of the present invention will be described. The cyclometalated complex of this invention can be used as a luminescent agent contained in the light emitting layer of light emitting elements, such as an organic EL element. In addition, the cyclometalated complex of the present invention can be used as a material such as a light-emitting paint.

  Next, a light-emitting element of the present invention that includes the above-described cyclometalated complex in a light-emitting layer will be described. A cross-sectional view of an example of the light-emitting element of the present invention is shown in FIG. In the light emitting device shown in FIG. 1, an anode 2 is formed on a transparent substrate 1 such as glass, and a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, and an electron transport are formed on the anode 2. The layer 6 and the electron injection layer 7 are stacked and the cathode 8 is formed on the electron injection layer 7. That is, a 5-layer type in which five layers of a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, and an electron injection layer 7 are laminated between the anode 2 and the cathode 8. It is a light emitting element.

  The light-emitting element of the present invention is not limited to the above-described five-layer type light-emitting element. In addition, a four-layer light-emitting element in which an electron transport layer is omitted from a five-layer light-emitting element may be used. Further, a three-layer light-emitting element in which the hole injection layer and the electron injection layer are omitted from the five-layer light-emitting element may be used. Further, a two-layer light-emitting element in which the light-emitting layer and the electron transport layer of the three-layer light-emitting element are used as one layer may be used. Alternatively, a single layer type in which only the light emitting layer is formed between the anode and the cathode may be used.

  The light emitting layer of the light emitting device of the present invention may contain the cyclometalated complex of the present invention as a guest light emitting agent or a host light emitting agent. When the cyclometalated complex of the present invention is used as a guest light-emitting agent, as a host light-emitting agent to be combined therewith, for example, a metal having an 8-quinolinol as a ligand such as tris (8-hydroxyquinolinato) aluminum. Complexes; carbazole derivatives such as CBP (4,4′-N, N′-dicarbazolebiphenyl); dicyanomethylene (DCM) s; coumarins; perylenes; rubrenes and the like.

  The operation of the light emitting device of the present invention is essentially the process of injecting electrons and holes from the electrode, the process of electrons and holes moving in the solid, the recombination of electrons and holes, and the triplet excitons. This process consists of a process of generating and a process of emitting light from the excitons, and these processes are not substantially different in any of the single-layer light-emitting element and the stacked light-emitting element. However, in the single layer type light emitting device, the characteristics of the above four processes can be improved only by changing the molecular structure of the luminescent agent, whereas in the stacked type light emitting element, a plurality of functions required in each process are provided. Since each material can be shared and optimized independently, it is generally easier to achieve the desired performance by configuring in a laminated type than in a single layer type.

  The light emitting element of the present invention can be used for a display device. Therefore, the present invention also provides a display device having the above light-emitting element. The display device of the present invention contains the cyclometalated complex of the present invention in the light emitting layer of the light emitting element.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and appropriate modifications are made within a range that can meet the above and the following purposes. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

The meanings of the abbreviations of the ligands used in the examples are as follows.
Ph ₂ pzH: 3,5-diphenylpyrazole Ph ₂ pz: a monovalent anion (3,5-diphenylpyrazolato) in which hydrogen ions are dissociated from 3,5-diphenylpyrazole which is monodentately coordinated to a Pt atom )
μ-Ph ₂ pz: a monovalent anion (3,5-diphenyl) in which hydrogen ions are dissociated from 3,5-diphenylpyrazole, which bridges Pt atoms or between Pt atoms and Au atoms or Pt atoms and Ag atoms. Pyrazolate)
Ph 2 _pz-κC, κN: chelate coordinating to Pt atoms in the N atom and C atom of the benzene ring of the pyrazole ring, is a hydrogen ion on the C atoms have moved to the N atom not involved in coordination bonds , Monovalent anion (3,5-diphenylpyrazolato) in which hydrogen ions are dissociated from 3,5-diphenylpyrazole
^{_{Ph 2 pz-κC, κ 2}} N, N ': chelate coordinated with the N atom and C atom of the benzene ring of the pyrazole ring to Pt atom, Au atom or an Ag atom in another N atom present in more pyrazole ring Divalent anion (3,5-diphenylpyrazolato dianion) in which two hydrogen ions are dissociated from 3,5-diphenylpyrazole, acting as a tridentate ligand by coordination to

Example 1 Synthesis and Characterization of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] (1) Synthesis of Complex [PtCl (Ph ₂ pz) (Ph ₂ pzH) ₂ ] (89.0 mg, 0.10 mmol) was added a methanol solution (5 mL) of KOH (16.8 mg, 0.30 mmol), acetonitrile (50 mL) was further added, and the mixture was refluxed for 24 hours under an argon atmosphere. The white suspension turned into a yellow suspension after the reaction. After the reaction solution was concentrated, the yellow solid was naturally filtered, washed with methanol, and dried under reduced pressure (yield 50.0 mg, yield 79%). Recrystallization was performed from dichloromethane / ethanol. The resulting _{[Pt 2 (Ph 2 pz-} κC, κN) 2 (μ-Ph 2 pz) 2] is a M ^II is Pt ^II, L ¹ is a ligand (L-1a) (i.e., R ^{1 is a} phenyl group, R ^{2 to} R ^{6 are} hydrogen atoms, and L ² is a ligand (L-2a) (that is, R ⁷ and R ^{9 are} phenyl groups, R ^{8 is a} hydrogen atom). It is a cyclometalated complex (1). The cyclometalated complex emitted yellowish green light in a solid state under irradiation with UV light (365 nm).

(2) Characterization Solubility: Soluble in acetonitrile, dichloromethane and chloroform IR (KBr): 3434 (m), 3375 (m), 3055 (w), 2922 (w), 2853 (w), 1602 (w) , 1552 (w), 1473 (m), 1346 (w), 1269 (w), 1156 (w), 1112 (w), 1072 (w), 1028 (w), 995 (w), 912 (w) , 791 (w), 728 (w), 618 (w), 577 (w)
FAB-MS (m / z): 1266.4 [M] ⁺

¹ H NMR: described in Table 1 (each item in Table 1 indicates, from the left, δ indicates the chemical shift (ppm) of the peak, shape indicates the peak shape, J indicates the binding constant (Hz), Int Indicates the peak intensity (relative value), and Assign. Indicates the attribution of the peak, and the same applies to other items of ¹ H NMR data.

X-ray structure _{analysis: [Pt 2 (Ph 2 pz} -κC, κN) 2 (μ-Ph 2 pz) 2] · The crystallographic data of CH ₂ Cl ₂ are described in Table 2 (each item in Table 2 From above, composition formula, formula weight, measurement temperature, measurement wavelength (MoKα ray = 0.71075Å), crystal system, space group, lattice constant (a, b, c, β), lattice volume, Z value, density , Linear absorption coefficient, number of independent reflections, final R value, R ₁ value, GOF value, etc. (The same applies to other items of crystallographic data.)

[Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] has its molecular structure determined by single crystal X-ray structural analysis. The crystallographic data is shown in Table 2, and the ORTEP diagram of the molecular structure is shown in FIG. [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] contains two Pt atoms and four 3,5-diphenylpyrazolates. Each Pt atom is chelated with cyclometalated 3,5-diphenylpyrazolato at C and N atoms, and using the remaining two coordination sites, the coordination plane of the two Pt is It has a structure in which two 3,5-diphenylpyrazolates are cross-linked so as to overlap. _{[Pt 2 (Ph 2 pz-} κC, κN) 2 (μ-Ph 2 pz) 2] Although the two geometric isomers of the C2 symmetric and the Cs symmetric contemplated in this cyclometallated complex have a C2 symmetry is doing. The Pt... Pt distance in [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] is 3.1398 (3) Å. The Pt-N distance of cyclometalated 3,5-diphenylpyrazolato is 1.982 (3) Å and 1.990 (4) Å, and the Pt-N distance of bridged 3,5-diphenylpyrazolato is It is in the range of 2.002 (3) to 2.128 (3) Å. The Pt-C distances are 2.016 (4) ４ and 2.011 (4) Å.

The photophysical properties of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] will be described. First, FIG. 3 shows an ultraviolet-visible absorption spectrum of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] in a dichloromethane solution. As shown in FIG. _{3, [Pt 2 (Ph 2} pz-κC, κN) 2 (μ-Ph 2 pz) 2] shows a broad absorption band with an absorption maximum at 258nm and 332 nm.

Next, FIG. 4 shows a solid state emission spectrum of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] excited by light having a wavelength of 355 nm (measurement temperature: 298 K). The solid-state emission quantum yield (Φ) of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] obtained by an absolute PL quantum yield measurement apparatus was 0.26. .

Next, FIG. 5 shows emission spectra of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] at 80K, 150K, 220K, and 298K. Table 3 shows the emission lifetime of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] obtained by a fluorescence lifetime measuring apparatus. The light emission lifetimes shown in Table 3 were calculated from analysis using a two-component exponential function (I (t) = A ₁ exp (−t / τ ₁ ) + A ₂ exp (−t / τ ₂ )). As shown in Table 3, since the emission lifetime of [Pt ₂ (Ph ₂ pz-κC, κN) ₂ (μ-Ph ₂ pz) ₂ ] is relatively long, this indicates that the emission from the excited triplet state ( That is, phosphorescence is considered.

Example _{2: [Pt 2 (Ph 2} pz-κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] Synthesis and characterization (1) Synthesis of complex [PtCl (Ph ₂ pz) (Ph ₂ pzH) ₂ ] (269.9 mg, 0.31 mmol) was added KOH (19.1 mg, 0.34 mmol) in methanol (5 mL) and acetonitrile (50 mL), and the reaction was performed under an argon atmosphere for 24 hours. Refluxed. The white suspension turned into a yellow suspension after the reaction. After concentration, the yellow solid was naturally filtered, washed with methanol, and dried under reduced pressure (yield 181.4 mg, yield 80%). Recrystallization was performed from dichloromethane / hexane. The resulting _{[Pt 2 (Ph 2 pz-} κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] is, M ^II is a Pt ^II, M ^I and M ^'I Is H ⁺ , L ³ is a ligand (L-3a) (that is, R ¹ : phenyl group, R ^{2 to} R ⁶ : hydrogen atom), and L ² is a ligand (L-2a). ) (That is, R ⁷ and R ⁹ : phenyl group, R ⁸ : hydrogen atom). One H ⁺ binds to the ligand (L-3a) to form Ph ₂ pz-κC, κN (that is, a monovalent anionic ligand (L-1a)). Two H ⁺ are combined with the ligand (L-2a) to form Ph ₂ pzH.

(2) Characterization Solubility: Soluble in dichloromethane and chloroform IR (KBr): 3376 (m), 3058 (m), 2360 (w), 2342 (w), 1646 (w), 1602 (w), 1473 (m), 1405 (w), 1272 (w), 1221 (w), 1072 (w), 1003 (w), 911 (w), 807 (w), 730 (w), 668 (w)
FAB-MS (m / z): 1487.5 [M] ⁺

¹ H NMR: described in Table 4

X-ray structure _{analysis: [Pt 2 (Ph 2 pz} -κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] a · CH ₃ CN · H ₂ O crystallographic data It is described in Table 5.

_{[Pt 2 (Ph 2 pz-} κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] has determined its molecular structure a single crystal X-ray structure analysis. The crystallographic data is shown in Table 5, and the ORTEP diagram of the molecular structure is shown in FIG. _{Pt 2 (Ph 2 pz-κC} , κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] , the two Pt atoms, one cyclometallated 3,5 diphenylpyraline Zolato, two 3,5-diphenylpyrazolates bridged between Pt atoms, monodentate 3,5-diphenylpyrazolate, and one 3,5-diphenylpyrazole are included. One 3,5-diphenylpyrazolato is chelated to Pt1 at the C and N atoms by cyclometallation, and the remaining 3,5 acting as bridging ligands -Diphenylpyrazolato is coordinated respectively. On the other hand, in addition to the two 3,5-diphenylpyrazolates acting as bridging ligands, Pt2 contains 3,5-diphenylpyrazolate and 3,5-diphenylpyrazole in monodentate one by one. Is ranked.

_{[Pt 2 (Ph 2 pz-} κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] Pt ··· Pt distance in is 3.2038 (5) Å. The Pt—C and Pt—N distances of cyclometalated 3,5-diphenylpyrazolato are 2.011 (7) Å and 1.996 (6) Å, respectively. Further, the Pt—N distance of the crosslinked 3,5-diphenylpyrazolato is in the range of 1.997 (5) to 2.118 (5) Å. The monodentate 3,5-diphenylpyrazolato and 3,5-diphenylpyrazole Pt—N distances are 2.022 Å (5) and 2.013 (5) Å, respectively.

_{[Pt 2 (Ph 2 pz-} κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] For photophysical properties will be described. First, FIG. 7 shows an ultraviolet-visible absorption spectrum of a dichloromethane solution of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)]. As shown in FIG. 7, [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] has an absorption maximum at 256 nm and a shoulder near 330 nm. Indicates.

Next, FIG. 4 shows a solid state emission spectrum of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] excited with light having a wavelength of 355 nm. (Measurement temperature: 298K). As shown in the emission spectrum, a slight vibration structure was observed. The solid state emission quantum yield (Φ) of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] is less than 0.01, It was not possible to measure accurately.

Next, FIG. 5 shows emission spectra of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] at 80K, 150K, 220K, and 298K. . Table 6 shows the emission lifetime of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] obtained by a fluorescence lifetime measuring apparatus. The light emission lifetimes shown in Table 6 were calculated from analysis using a two-component exponential function (I (t) = A ₁ exp (−t / τ ₁ ) + A ₂ exp (−t / τ ₂ )). Since the emission lifetime of [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] is relatively long, this is It is considered to emit light (ie, phosphorescence).

Example 3 Synthesis and Characterization of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] (1) Synthesis of Complex [Pt ₂ (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₂ (Ph ₂ pz) (Ph ₂ pzH)] (37.2 mg, 0.025 mmol) to AuCl (SC ₄ H ₈ ) (10.3 mg, 0.032 mmol) in methanol (10 mL), triethylamine (10 μL, 0.063 mmol), and dichloromethane (10 mL) were added, and the mixture was stirred at room temperature for 1 hour in an argon atmosphere. The brown solution was concentrated and the precipitated brown solid was collected. The solid was naturally filtered, washed with water and methanol, and dried under reduced pressure (yield 16.8 mg, yield 40%). Recrystallization was performed from dichloromethane / hexane to obtain yellow crystals. The resulting _{[Pt 2 Au (Ph 2 pz} -κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] is, M ^II is a Pt ^II, M ^I is H ⁺ M ′ ^I is Au ^I , L ³ is a ligand (L-3a) (that is, R ¹ : phenyl group, R ^{2 to} R ⁶ : hydrogen atom), and L ² is It is a cyclometalated complex (2) which is a ligand (L-2a) (that is, R ⁷ and R ⁹ : phenyl group, R ⁸ : hydrogen atom). H ⁺ is bonded to the ligand (L-2a) to form Ph ₂ pzH. The cyclometalated complex emitted yellowish green light in a solid state under irradiation with UV light (365 nm).

(2) Characteristic evaluation Solubility: Soluble in dichloromethane, chloroform and toluene IR (KBr): 3375 (m), 3059 (m), 2986 (w), 2934 (w), 1799 (w), 1603 (w) , 1569 (w), 1509 (w), 1474 (s), 1430 (m), 1344 (w), 1271 (w), 1179 (w), 1114 (w), 1072 (w), 1031 (w) , 1004 (w), 913 (w), 876 (w), 806 (w), 729 (w), 668 (w)
FAB-MS (m / z): 1683.5 [M] ⁺

¹ H NMR: described in Table 7

X-ray structural analysis: crystallographic data of [Pt ₂ Au (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] · 0.5CH ₂ Cl ₂ is shown in Table 8. .

_{[Pt 2 Au (Ph 2 pz} -κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] has determined its molecular structure a single crystal X-ray structure analysis. The crystallographic data is shown in Table 8, and the ORTEP diagram of the molecular structure is shown in FIG. [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] includes two Pt atoms, one Au atom, cyclometalated, and A total of three 3,5-diphenylpyrazolato dianions crosslinked between Pt ... Au, and 3,5-diphenylpyrazolato crosslinked between Pt ... Pt and between Pt ... Au One monodentate 3,5-diphenylpyrazole.

In [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)], the Pt... Pt distance is 3.2147 (4) Å, Pt · ..Au distance is 3.4290 (5) Å and 3.5305 (5) Å, and Au-N distance is 1.992 (7) Å and 2.045 (7) Å. The Pt—C and Pt—N distances of the cyclometalated 3,5-diphenylpyrazolato dianion are 2.016 (7) Å and 1.980 (7) Å, respectively. Further, the Pt—N distance of the crosslinked 3,5-diphenylpyrazolato is in the range of 2.002 (6) to 2.145 (6) Å. The Pt—N distance of monodentate 3,5-diphenylpyrazole is 2.030 (6) Å.

The photophysical properties of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] will be described. First, an ultraviolet-visible absorption spectrum of a dichloromethane solution of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] is shown in FIG. As shown in FIG. _{11, [Pt 2 Au (Ph} 2 pz-κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] is the absorption maximum at 260 nm, in the vicinity of 330nm Show shoulders.

Fig then excited by light with a wavelength of _{355nm [Pt 2 Au (Ph 2} pz-κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] The emission spectrum of solid state 12 (measurement temperature: 298K). As shown in this emission spectrum, a remarkable vibration structure was confirmed. Further, the solid state emission quantum of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] obtained by an absolute PL quantum yield measuring apparatus. The yield (Φ) was 0.03.

Next, FIG. 13 shows emission spectra of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] at 80K, 150K, and 298K. Table 9 shows the emission lifetime of [Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] obtained by a fluorescence lifetime measuring apparatus. The light emission lifetime shown in Table 9 was calculated from the analysis using a two-component exponential function (I (t) = A ₁ exp (−t / τ ₁ ) + A ₂ exp (−t / τ ₂ )). As shown in Table 9, since the emission lifetime of Pt ₂ Au (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] is relatively long, It is considered that light is emitted from an excited triplet state (that is, phosphorescence).

Example 4: Synthesis and characterization of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] (1) Synthesis of complex [Pt _{2 (Ph 2 pz-κC, κN} ) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] (74.3mg, 0.05mmol) in methanol AgBF ₄ in (15 mg, 0.078 mmol) (5 mL) and triethylamine (40 μL, 0.25 mmol) were added, dichloromethane (10 mL) was further added, and the mixture was stirred at room temperature for 3 hours while being protected from light. The yellow solution was concentrated, and the precipitated white yellow solid was collected. The solid was naturally filtered, washed with methanol, and dried under reduced pressure (yield 40.8 mg, yield 51%). The resulting _{[Pt 2 Ag (Ph 2 pz} -κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] is, M ^II is a Pt ^II, M ^I is H ⁺ M ′ ^I is Ag ^I , L ³ is a ligand (L-3a) (that is, R ¹ : phenyl group, R ^{2 to} R ⁶ : hydrogen atom), and L ² is It is a cyclometalated complex (2) which is a ligand (L-2a) (that is, R ⁷ and R ⁹ : phenyl group, R ⁸ : hydrogen atom). H ⁺ is bonded to the ligand (L-2a) to form Ph ₂ pzH. This cyclometalated complex emitted blue-green light in a solid state under irradiation of UV light (365 nm).

(2) Characteristic evaluation Solubility: Soluble in dichloromethane, chloroform, acetonitrile and toluene IR (KBr): 3372 (w), 3059 (m), 3033 (w), 2965 (w), 2931 (w), 1943 ( w), 1877 (w), 1801 (w), 1749 (w), 1569 (m), 1472 (s), 1405 (w), 1337 (w), 1300 (w), 1280 (w), 1223 ( w), 1156 (w), 1110 (w), 1072 (w), 1029 (w), 1004 (w), 792 (w), 755 (m), 694 (m)
FAB-MS (m / z): 1595.5 [M] ⁺

¹ H NMR: described in Table 10

X-ray structural analysis: crystallographic data of [Pt ₂ Ag (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] · 0.5CH ₂ Cl ₂ is shown in Table 11. .

_{[Pt 2 Ag (Ph 2 pz} -κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] has determined its molecular structure a single crystal X-ray structure analysis. The crystallographic data is shown in Table 11, and the ORTEP diagram of the molecular structure is shown in FIG. The crystal structure of [Pt ₂ Ag (Ph ₂ pz-κC, κN) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] · 0.5CH ₂ Cl ₂ is the same as that of Example 3 [Pt ₂ Au (Ph ₂ ^{pz-κC, κ 2 N,} N ') (μ-Ph 2 pz) is ₃ (Ph _{2 pzH)]} of · 0.5CH ₂ Cl ₂ crystal structure isomorphous. That is, [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] includes two Pt atoms, one Ag atom, and a cyclometalated group. In addition, one 3,5-diphenylpyrazolato dianion crosslinked between Pt ... Ag and 3,5-diphenylpyrazolato crosslinked between Pt ... Pt and between Pt ... Ag 3. One monodentate 3,5-diphenylpyrazole coordinated.

In [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)], the Pt... Pt distance is 3.2486 (5) Å, Pt · The Ag distance is 3.3687 (7) ３．５ and 3.5422 (8) Å, and the Ag-N distance is 2.118 (7) ２．０ and 2.092 (7) Å.

The photophysical properties of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] will be described. First, FIG. 15 shows an ultraviolet-visible absorption spectrum of a dichloromethane solution of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)]. As shown in FIG. _{15, [Pt 2 (Ph 2} pz-κC, κN) (μ-Ph 2 pz) 2 (Ph 2 pz) (Ph 2 pzH)] shows an absorption maximum at 255 nm.

Fig then excited by light with a wavelength of _{355nm [Pt 2 Ag (Ph 2} pz-κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] The emission spectrum of solid state 16 shows. As shown in this emission spectrum, a remarkable vibration structure was confirmed. Moreover, it was determined by the absolute PL quantum yield measuring apparatus _{[Pt 2 Ag (Ph 2 pz} -κC, κ 2 N, N ') (μ-Ph 2 pz) 3 (Ph 2 pzH)] emission quantum solid state The yield (Φ) was 0.05.

Next, FIG. 17 shows emission spectra of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] at 80K, 150K, 220K, and 298K. Show. Table 12 shows the emission lifetime of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] obtained by a fluorescence lifetime measuring apparatus. The light emission lifetimes shown in Table 12 were calculated from analysis using a two-component exponential function (I (t) = A ₁ exp (−t / τ ₁ ) + A ₂ exp (−t / τ ₂ )). As shown in Table 12, the light emission lifetime of [Pt ₂ Ag (Ph ₂ pz-κC, κ ² N, N ′) (μ-Ph ₂ pz) ₃ (Ph ₂ pzH)] is relatively long. Is considered to be emission from an excited triplet state (ie, phosphorescence).

  The light absorption band of the cyclometalated complex of the present invention is shifted to a longer wavelength side than the conventional metal complex, and can be excited with a lower energy than the conventional metal complex. Such a cyclometalated complex of the present invention is useful as a raw material for light-emitting elements and display devices.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (7)

Formula (1):
[(M ^II ) ₂ (L ¹ ) ₂ (L ² ) ₂ ] (1)
[In formula (1), M ^II represents Pt ^II or Pd ^II .
L ¹ is a formula (L-1):

{In Formula (L-1), R ^{1 to} R ⁶ each independently represents a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. R ³ and R ⁴ or R ⁴ and R ⁵ are bonded to form a condensed aromatic hydrocarbon ring which may have a substituent together with the benzene ring. }
The monovalent anionic ligand represented by these is shown.
L ² represents the formula (L-2):

{In Formula (L-2), R ^{7 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Show. }
The monovalent anionic ligand represented by these is shown. ]
And L ¹ is chelate-coordinated to M ^II with the N atom of the pyrazole ring and the C atom of the benzene ring. Formula (2):
[(M ^II ) ₂ (M ^I ) (M ′ ^I ) (L ³ ) (L ² ) ₄ ] (2)
[In the formula (2), M ^II represents Pt ^II or Pd ^II .
M ^I represents H ⁺ .
M ′ ^I represents H ⁺ , Au ^I , Ag ^I , Cu ^I , Hg ^I , Tl ^I or Pb ^I.
L ³ represents formula (L-3):

{In Formula (L-3), R ^{1 to} R ⁶ each independently represents a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. R ³ and R ⁴ or R ⁴ and R ⁵ are bonded to form a condensed aromatic hydrocarbon ring which may have a substituent together with the benzene ring. }
The bivalent anionic ligand represented by these is shown.
L ² represents the formula (L-2):

{In Formula (L-2), R ^{7 to} R ⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Show. }
The ligand represented by these is shown. ]
And L ³ is chelate-coordinated to M ^II by the N atom of the pyrazole ring and the C atom of the benzene ring. The cyclometalated complex according to claim 1 or 2, wherein M ^II is Pt ^II . R ⁶ is cyclometallated complex according to any one of claims 1 to 3 is a hydrogen atom or a halogen atom. R < ¹ >, R < ⁷ > and R < ⁹ > are the phenyl groups which may have a substituent, The cyclometalation complex as described in any one of Claims 1-4.   The light emitting element which has a light emitting layer containing the cyclometalation complex as described in any one of Claims 1-5.   A display device comprising the light emitting element according to claim 6.

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