Cyclometalated transition metal complex and organic electroluminescent device using the same

1. A transition metal complex represented by Formula 1:

where M is a transition metal;

X is one of N and C;

L is a neutral ligand;

CY1 and CY2 are each independently an aromatic or aliphatic ring system, and CY1 contains a nitrogen atom that is bonded to M, and CY2 contains X that is bonded to M;

m is 1 or 2; and

A 1 , A 2 , A 3 , and A 4 are each independently imidazole, pyrazole, a derivative of the imidazole, or a derivative of pyrazole.

2. The transition metal complex of claim 1 , wherein the compound represented by Formula 1 is represented by one of Formulae 2 and 3:

where M is a transition metal;

X is one of N and C;

L is a neutral ligand;

CY1 and CY2 are each independently an aromatic or aliphatic ring system;

m is 1 or 2;

R 1 , R 2 , R 3 , and R 4 are each independently a substituent or H; and

n is 1, 2, or 3.

3. The transition metal complex of claim 1 , wherein A 1 , A 2 , A 3 , and A 4 are each independently substituted with one substituent selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a heterocyclicoxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, an arylthio group, a heterocyclicthio group, a sulfonyl group, a sulfynyl group, an ureido group, a phosphoric acid amid group, a hydroxyl group, a mercapto group, a halogen atom, a cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamine acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group a silyl group, and a silyloxy group.

4. The transition metal complex of claim 1 , wherein the compound represented by Formula 1 is represented by Formula 5:

where M is a transition metal;

L is a neutral ligand;

m is 1 or 2;

R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R, and R′ are each independently a substituent or a hydrogen atom where n is 1, 2, or 3; and

n 1 is 3.

5. The transition metal complex of claim 1 , wherein M is Ru, Rh, Os, Ir, Pt, Or Au.

6. The transition metal complex of claim 1 , wherein the compound represented by Formula 1 is represented by one of Formulae 6 through 16:

7. An organic electroluminescent device comprising an organic layer interposed between a pair of electrodes, the organic layer comprising the transition metal complex of claim 1 .

8. A transition metal complex represented by Formula 1:

where M is a transition metal;

CY1 contains a nitrogen atom that is bonded to M, and CY2 has X that is bonded to M;

X is one of N and C;

L is a neutral ligand;

m is 1 or 2; and

A 1 , A 2 , A 3 and A 4 are each independently imidazole, pyrazole, a derivative of the imidazole, or a derivative of pyrazole; and

CY1-CY2 formed by CY1 and CY2 is a cyclometalated ligand represented by one of Formulae 1-(i) to 1-(xxiii):

where R 1 , R 2 , R 3 , R 4 , and R 5 are single-substituted or multi-substituted functional groups, and R 1 , R 2 , R 3 , R 4 , and R 5 are each independently H, a halogen atom, —OR, —N(R) 2 , —P(R) 2 , —POR, —PO 2 R, —PO 3 R, —SR, —Si(R) 3 , —B(R) 2 , —B(OR) 2 , —C(O)R, —C(O)OR, —C(O)N(R), —CN, —NO 2 , —SO 2 , —SOR, —SO 2 R, —SO 3 R, a C1-C20 alkyl group, or a C6-C20 aryl group, where R is a substituent or a hydrogen atom.

9. The transition metal complex of claim 8 , wherein L of Formula 1 is represented by one selected from the group consisting of Formulae 1-(xxix) to 1-(xxxx):

where R, R 1 , R 2 , and R 3 of Formulae 1-(xxix) to 1-(xxxx) are each independently an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or a heteroaryl group.

10. An organic electroluminescent device comprising an organic layer interposed between a pair of electrodes, the organic layer composed of the transition metal complex of claim 8 .

11. An organic electroluminescent device, comprising:

a pair of electrodes; and

an organic layer interposed between the pair of electrodes, the organic layer comprising an emission layer composed of the transition metal complex represented by Formula 1:

where M is a transition metal;

X is one of N and C;

L is a neutral ligand;

CY1 and CY2 are each independently an aromatic or aliphatic ring system, and CY1 has a nitrogen atom that is bonded to M, and CY2 has X that is bonded to M;

m is 1 or 2; and

A 1 , A 2 , A 3 , and A 4 are each independently imidazole, pyrazole, a derivative of the imidazole, or a derivative of pyrazole.

12. The organic electroluminescent device of claim 11 , wherein the emission layer further comprises at least one host selected from the group consisting of at least one polymer host, a mixture of a polymer host and a low molecular weight host, a low molecular weight host, and a non-emissive polymer host.

13. The organic electroluminescent device of claim 11 , wherein the emission layer further comprises a green emissive material or a red emissive material.

14. The organic electroluminescent device of claim 11 , wherein the transition metal complex is represented by one of Formulae 2 and 3:

where R 1 , R 2 , R 3 , and R 4 are each independently a substituent or H; and

n is 1, 2, or 3.

15. The organic electroluminescent device of claim 11 , wherein A 1 , A 2 , A 3 , and A 4 are each independently substituted with one substituent selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a heterocyclicoxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, an arylthio group, a heterocyclicthio group, a sulfonyl group, a sulfynyl group, an ureido group, a phosphoric acid amid group, a hydroxyl group, a mercapto group, a halogen atom, a cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamine acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group a silyl group, and a silyloxy group.

16. The organic electroluminescent device of claim 11 , wherein the compound represented by Formula 1 is represented by Formula 5:

where R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R, and R′ are each independently a substituent or a hydrogen atom where n is 1, 2, or 3; and

n 1 is 3.

17. The organic electroluminescent device of claim 11 , wherein M is Ru, Rh, Os, Ir, Pt, or Au.

18. The organic electroluminescent device of claim 11 , wherein the transition metal complex is represented by one of Formulae 6 through 16:

19. The organic electroluminescent device of claim 18 , wherein the organic layer further comprises a green emissive material or a red emissive material.

20. The organic electroluminescent device of claim 11 , wherein the organic electroluminescent device emits light of 400 nm to 650 nm.