METHOD FOR PRODUCING CYCLOMETALATED IRIDIUM COMPLEX, AND NOVEL IRIDIUM COMPOUND PREFERABLY USED FOR THE METHOD

Abstract

A method for producing a cyclometalated iridium complex by allowing an iridium compound and an aromatic bidentate ligand to react each other. In particular, the method is characterized by allowing a -diketonate salt represented by General Formula (4) to coexist in a reaction system for reaction. By adding the -diketonate salt into the reaction system, stability of a reaction intermediate product between the iridium compound and the aromatic bidentate ligand improves. Therefore, yield of the cyclometalated iridium complex can improve. The cyclometalated iridium complex produced in accordance with the present invention is useful as a phosphorescent material for use in an organic EL element, for example.

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Claims

1. A method for producing an iridium complex, in a method for producing a cyclometalated iridium complex represented by General Formula (3) described below including allowing an iridium compound represented by General Formula (1) described below and an aromatic bidentate ligand represented by General Formula (2) described below to react each other, the method comprising: allowing a -diketonate salt represented by General Formula (4) described below to coexist in a reaction system for reaction. ##STR00016## (In General Formula (1), Ir represents an iridium atom. O represents an oxygen atom. X represents a halogen atom. Y represents a counter cation. Each of R.sup.1 to R.sup.6 is, independently, a hydrogen atom, an alkyl group, or an aryl group. Some or all of hydrogen atoms in the alkyl group or the aryl group may be substituted with halogen atoms. R.sup.1 to R.sup.6 may each bond with adjacent ones to form a ring structure.) ##STR00017## (In General Formula (2), N represents a nitrogen atom. C represents a carbon atom. H represents a hydrogen atom. CyA represents a ring group of a five-membered ring or a six-membered ring containing a nitrogen atom. CyB represents a ring group of a five-membered ring or a six-membered ring containing a carbon atom. CyA and CyB may bond each other to form a ring structure.) ##STR00018## (In General Formula (3), Ir represents an iridium atom. N represents a nitrogen atom. C represents a carbon atom. X represents a halogen atom. CyA represents a ring group of a five-membered ring or a six-membered ring containing a nitrogen atom, and bonds with iridium via the nitrogen atom. CyB represents a ring group of a five-membered ring or a six-membered ring containing a carbon atom, and bonds with iridium via the carbon atom. CyA and CyB may bond each other to further form a ring structure.) ##STR00019## (In General Formula (4), M represents alkali metal or alkali earth metal. O represents an oxygen atom. For m, 1 or 2 is represented. When M is alkali metal, m=1. When M is alkali earth metal, m=2. Each of R.sup.7 to R.sup.9 is, independently, a hydrogen atom, an alkyl group, or an aryl group. Some or all of hydrogen atoms in the alkyl group or the aryl group may be substituted with halogen atoms. R.sup.7 to R.sup.9 may each bond with adjacent ones to form a ring structure.)

2. The production method according to claim 1, wherein CyA is one of a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a cinnoline ring, a phthalazine ring, a quinazoline ring, a naphthyridine ring, an imidazole ring, a pyrazole ring, a triazole ring, a tetrazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, and a thiadiazole ring, and wherein CyB is one of a benzene ring, a naphthalene ring, an anthracene ring, a carbazole ring, a fluorene ring, a furan ring, a thiophene ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a cinnoline ring, a phthalazine ring, a quinazoline ring, a naphthyridine ring, an imidazole ring, a pyrazole ring, a triazole ring, a tetrazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, and a thiadiazole ring.

3. The production method according to claim 1, wherein CyA is a pyridine ring or an imidazole ring, and wherein CyB is a benzene ring.

4. A composition comprising a mixture consisting of: the iridium compound represented by General Formula (1); and the -diketonate salt represented by General Formula (4).

5. The composition according to claim 4, wherein a mixed moler ratio of the -diketonate salt represented by General Formula (4) ranges from 0.01 times moles to 1000 times moles inclusive, per mole of the iridium compound represented by General Formula (1).

6. An iridium compound represented by General Formula (15). ##STR00020## (In General Formula (15), Ir represents an iridium atom. O represents an oxygen atom. X represents a halogen atom. Y represents a counter cation. Each of R.sup.1, R.sup.3, R.sup.4, and, R.sup.6 is, independently, an alkyl group having a carbon number ranging from 1 to 10 inclusive. However, at least either R.sup.1 or R.sup.3 is an alkyl group substituted with fluorine, and at least either R.sup.4 or R.sup.6 is an alkyl group substituted with fluorine.)

7. The iridium compound according to claim 6, wherein one of R.sup.1 and R.sup.3 is a trifluoromethyl group, and another one is a methyl group, and wherein one of R.sup.4 and R.sup.6 is a trifluoromethyl group, and another one is a methyl group.

8. The production method according to claim 2, wherein CyA is a pyridine ring or an imidazole ring, and wherein CyB is a benzene ring.

Description

EXAMPLE 1

Synthesizing (T-1) (When Adding -Diketonate Salt Into Reaction System)

[0099] The iridium compound (Ir-1) in an amount of 145.3 mg (0.3 m moles), the ligand (L-1) in an amount of 279.0 mg (1.8 m moles), sodium acetylacetonate hydrate serving as a -diketonate salt in an amount of 91.6 mg (0.75 m moles), and, ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-1). Yield was 80%.

Comparative Example 1 Synthesizing (T-1) (When Not Adding -Diketonate Salt Into Reaction System)

[0100] The iridium compound (Ir-1) in an amount of 145.3 mg (0.3 m moles), the ligand (L-1) in an amount of 279.0 mg (1.8 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were a mixture of (T-1) and (D-1). Yield of (T-1) and (D-1) was calculated to 71% and 22%, respectively, based on integrated values of .sup.1H-NMR.

EXAMPLE 2

Synthesizing (T-1) (When Adding -Diketonate Salt Into Reaction System)

[0101] The iridium compound (Ir-2) in an amount of 167.0 mg (0.3 m moles), the ligand (L-1) in an amount of 162.7 mg (1.05 m moles), sodium acetylacetonate hydrate serving as a -diketonate salt in an amount of 44.0 mg (0.36 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-1). Yield was 87%.

Comparative Example 2 Synthesizing (T-1) (When Not Adding -Diketonate Salt Into Reaction System)

[0102] The iridium compound (Ir-2) in an amount of 167.0 mg (0.3 m moles), the ligand (L-1) in an amount of 162.7 mg (1.05 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were a mixture of (T-1) and (D-1). Yield of (T-1) and (D-1) was calculated to 22% and 73%, respectively, based on integrated values of .sup.1H-NMR.

EXAMPLE 3

Synthesizing (T-2) (When Adding -Diketonate Salt Into Reaction System)

[0103] The iridium compound (Ir-2) in an amount of 167.0 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), sodium acetylacetonate hydrate serving as a -diketonate salt in an amount of 366.3 mg (3.0 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-2). Yield was 63%.

Comparative Example 3 Synthesizing (T-2) (When Not Adding -Diketonate Salt Into Reaction System)

[0104] The iridium compound (Ir-2) in an amount of 167.0 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were a mixture of (T-2) and (D-2). Yield of (T-2) and (D-2) was calculated to 27% and 20%, respectively, based on integrated values of .sup.1H-NMR.

EXAMPLE 4

Synthesizing (T-2) (When Adding -Diketonate Salt Into Reaction System)

[0105] The iridium compound (Ir-1) in an amount of 145.3 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), sodium acetylacetonate hydrate serving as a -diketonate salt in an amount of 183.2 mg (1.5 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-2). Yield was 52%.

Comparative Example 4 Synthesizing (T-2) (When Not Adding -Diketonate Salt Into Reaction System)

[0106] The iridium compound (Ir-1) in an amount of 145.3 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 17 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were a mixture of (T-2) and (D-2). Yield of both (T-2) and (D-2) was calculated to 13% based on integrated values of .sup.1H-NMR.

EXAMPLE 5

Synthesizing (T-2) (When Adding -Diketonate Salt Into Reaction System)

[0107] The iridium compound (Ir-3) in an amount of 182.5 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), sodium acetylacetonate hydrate serving as a -diketonate salt in an amount of 366.3 mg (3.0 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 180 C. for 34 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-2). Yield was 68%.

EXAMPLE 6

Synthesizing (T-2) (When Adding -Diketonate Salt Into Reaction System)

[0108] The iridium compound (Ir-2) in an amount of 167.0 mg (0.3 m moles), the ligand (L-2) in an amount of 472.2 mg (1.8 m moles), sodium acetylacetonate hydrate serving as a 6-diketonate salt in an amount of 366.3 mg (3.0 m moles), and ethylene glycol in an amount of 2.5 ml were allowed to thermally react in a three-neck flask under an argon atmosphere at a temperature of 160 C. for 34 hours. After the reaction, the reaction solution was cooled to a room temperature. Separated yellow solids were cleaned with methanol. As a result of analysis of .sup.1H-NMR, the separated yellow solids were the desired iridium complex (T-2). Yield was 60%.

[0109] As the results of experiments described above, with Examples 1 to 6 of the production method according to the present invention, where the -diketonate salt is added into the reaction system, only the desired tris-cyclometalated iridium complexes can be obtained. On the other hand, it has been found that, with a conventional production method where the -diketonate salt is not added into the reaction system, byproducts mix into the target tris-cyclometalated iridium complexes, significantly lowering yield and degrees of purity of the desired cyclometalated iridium complexes.

[0110] In Examples 3 to 5, (T-2) has been produced as the cyclometalated iridium complex. The iridium compounds applied in the examples can be ordered as (Ir-3), (Ir-2), and (Ir-1) in a descending order of yield. As a result, it can be understood that, in General Formula (1), when at least either R.sup.1 or R.sup.3 is an alkyl group substituted with fluorine, and at least either R.sup.4 or R.sup.6 is an alkyl group substituted with fluorine, yield of the desired cyclometalated iridium complex (T-2) has significantly improved to 68%. This is due to that, by introducing an electron attractive group, i.e., a fluorine atom, into an iridium compound, a bond between iridium and a ligand in the iridium compound (Ir-3) weakens, allowing the ligand (L-2) to easily react.

[0111] As described above, by using the production method according to the present invention, an amount of use of an expensive organic ligand can be reduced. In addition, a high purity cyclometalated iridium complex can be obtained, significantly lowering costs regarding purification and production.

INDUSTRIAL APPLICABILITY

[0112] According to the present invention, a high purity cyclometalated iridium complex to be used as a phosphorescent material for use in an organic EL element, for example, can be produced at higher yield. Further, by using the cyclometalated iridium complex produced with the method according to the present invention, a high efficiency organic EL element, for example, can be produced. The present invention is highly useful as a method for producing a cyclometalated iridium complex to be used as a phosphorescent material for use in organic electrolytic light-emitting (EL) elements, organic electrochemical light-emitting (ECL) elements, light-emitting sensors, photosensitive dyes, photocatalysts, light-emitting probes, and various light sources, for example.