Organic electroluminescent heterocyclic carbene metal complexes and devices containing the same

Abstract

A method of forming compounds that comprise a heterocyclic carbene ligand is provided. In particular, an oxazole or a thioazole carbene are used in place of the traditional imidazole carbene. These compounds may be used in OLEDs to provide devices having improved properties, such as stability and color-tuning.

Claims

1. A compound comprising a ligand L having the structure: ##STR00224## wherein X.sub.1 is S or O; wherein X.sub.2, X.sub.3, X.sub.4, and X.sub.5 are independently C or N; wherein at least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N; wherein R.sub.1 may represent mono-substitution up to the maximum possible substitutions; wherein each R.sub.1 is independently hydrogen or a substituent selected from the group consisting of deuterium, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof; wherein at least one R.sub.1 is selected from the group consisting of deuterium, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof; wherein R.sub.A may represent mono, di, tri, or tetra substitutions, or no substitutions; wherein R.sub.A is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrite, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein two adjacent substituents of R.sub.A are optionally joined to form a fused ring; wherein A is a 5-membered or 6-membered carbocyclic or heterocyclic ring; wherein the ligand L is coordinated to a metal M selected from Ir and Os; wherein ligand L may be linked with other moieties coordinated to the metal M to comprise a tridentate, tetradentate, or pentadentate ligand; and wherein the compound is heteroleptic.

2. The compound of claim 1, wherein A is benzene.

3. The compound of claim 1, wherein the ligand has the formula: ##STR00225## wherein at least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N; wherein R.sub.2 may represent mono, di, tri or tetra substitutions; wherein each R.sub.2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

4. The compound of claim 1, wherein the ligand has the formula: ##STR00226## wherein at least two of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N; wherein R.sub.2 may represent mono, di, tri or tetra substitutions; wherein each R.sub.2 is independently hydrogen or a substituent selected from the group consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

5. A first device comprising an organic light emitting device, comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound comprising a ligand L having the structure: ##STR00227## wherein X.sub.1 is S or O; wherein X.sub.2, X.sub.3, X.sub.4, and X.sub.5 are independently C or N; wherein at least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N; wherein R.sub.1 may represent mono-substitution up to the maximum possible substitutions; wherein each R.sub.1 is independently hydrogen or a substituent selected from the group consisting of deuterium, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof; wherein at least one R.sub.1 is selected from the group consisting of deuterium, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof; wherein R.sub.A may represent mono, di, tri, or tetra substitutions, or no substitutions; wherein R.sub.A is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfanyl, sulfonyl, phosphino, and combinations thereof; wherein two adjacent substituents of R.sub.A are optionally joined to form a fused ring; wherein A is a 5-membered or 6-membered carbocyclic or heterocyclic ring; wherein the ligand L is coordinated to a metal M selected from Ir and Os; wherein ligand L may be linked with other moieties coordinated to the metal M to comprise a tridentate, tetradentate, or pentadentate ligand; and wherein the compound is heteroleptic.

6. The first device of claim 5, wherein the organic layer is an emissive layer and the compound is an emissive dopant.

7. The first device of claim 5, wherein the organic layer further comprises a host.

8. The first device of claim 7, wherein the host is a metal complex.

9. The first device of claim 8, wherein the metal complex is selected from the group consisting of: ##STR00228## wherein (ON) is a bidentate ligand having metal coordinated to atoms O and N; wherein L is an ancillary ligand; and wherein m is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

10. The first device of claim 7, wherein the host is a compound that comprises at least one of the chemical groups selected from the group consisting of: ##STR00229## wherein each of R.sub.1 and R.sub.2 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein k is an integer from 0 to 20; and wherein each of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are independently selected from the group consisting of CH and N.

11. A process for making a carbene metal complex, comprising: reacting a copper dichloride carbene dimer with a metal precursor to yield a carbene metal complex which is a compound according to claim 1, wherein the metal precursor comprises Ir or Os.

12. The process of claim 11, further comprising reacting a carbene salt with copper-t-butoxide to yield a copper dichloride carbene dimer, prior to reacting the copper dichloride carbene dimer with the metal precursor.

13. The process of claim 11, wherein the metal precursor is selected from the group consisting of [IrCl(1,5-cyclooctadiene)].sub.2 and OsCl.sub.2(dimethylsulfoxide).sub.4.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an organic light emitting device.

(2) FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

(3) FIG. 3 shows a carbene ligand as described herein.

DETAILED DESCRIPTION

(4) Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an exciton, which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.

(5) The initial OLEDs used emissive molecules that emitted light from their singlet states (fluorescence) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

(6) More recently, OLEDs having emissive materials that emit light from triplet states (phosphorescence) have been demonstrated. Baldo et al., Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices, Nature, vol. 395, 151-154, 1998; (Baldo-I) and Baldo et al., Very high-efficiency green organic light-emitting devices based on electrophosphorescence, Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (Baldo-II), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

(7) FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, and a cathode 160. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

(8) More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

(9) FIG. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230, device 200 may be referred to as an inverted OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one example of how some layers may be omitted from the structure of device 100.

(10) The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is understood that embodiments of the invention may be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be omitted entirely, based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many of the examples provided herein describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an organic layer disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic materials as described, for example, with respect to FIGS. 1 and 2.

(11) Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2. For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entireties.

(12) Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. Pat. No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink-jet and OVJD. Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

(13) Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide variety of consumer products, including flat panel displays, computer monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.).

(14) The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

(15) The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group, and heteroaryl are known to the art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein by reference.

(16) Carbene iridium complexes are new class of phosphorescent dopant materials, which can provide various colors when used as emissive dopants in an OLED device. An overwhelming majority of N heterocyclic carbenes (NHC) ligands are derived from the imidazole (C.sub.3H.sub.4N.sub.2) framework. As research in NHC carbene metal complexes in OLEDs continues to advance at a vigorous pace, there is a strong need to develop other heterocyclic systems that can be adapted to the demands of different OLED materials. In particular, compounds in which one of the N atoms in an imidazole is replaced with an O atom to form an oxazole or with an S atom to form a thioazole are provided herein (as illustrated in FIG. 3). Additionally, a novel methodology to synthesize heterocyclic carbene metal complexes is provided. These compounds may lead to unique device properties in OLEDs, including improved stability and improved color-tuning.

(17) There are many beneficial features of the heterocyclic carbene metal complexes provided herein, including a reducible carbene moiety, i.e., reversible reduction, short excited state lifetime and a novel ligation method. First, imidazole-based carbene metal complexes generally do not have reversible reduction by CV measurement. In general, imidazole-based carbenes have a high LUMO that is difficult to reduce. This can lead to extremely high LUMO and electron instability. The oxazole and thioazole heterocyclic-based carbene metal complexes provided herein have reversible reduction and a shallow LUMO. Without being bound by theory, it is believed that the reversible reduction may improve the electron stability of these compounds when used as a dopant. By using the oxazole and thioazole heterocyclic carbenes configuration, the carbene moiety may become more reducible. With a N-containing aromatic ring fused into this heterocyclic carbene ring, the LUMO level may be further reduced. In other words, it may be easier to lower the LUMO of oxazole and thioazole heterocyclic carbenes compared to imidazole-based carbenes, which may allow for better device stability.

(18) Second, iridium carbene complexes generally have a long excited state lifetime due to poor MLCT mixing. The oxazole and thioazole heterocyclic carbene metal complexes provided herein, however, may have shorter excited state lifetimes. Fusion of a N-containing aromatic ring to this heterocyclic carbene ring is not expected to alter the shortened excited state lifetime demonstrated by these compounds.

(19) Third, the traditional ligation method via Ag.sub.2O fails for these heterocyclic based carbene metal complexes. These heterocyclic carbenes are more difficult to attach to metals than their corresponding imidazole carbene counterparts. Therefore, a new ligation method via copper carbene complexes has been developed. The free carbene stability for N, S-based carbenes is worse than conventional imidazole-based carbenes due to the lack of steric protection. Without being bound by theory, it is believed that the conventional transmetallation via Ag.sub.2O was not successful for the oxazole and thioazole heterocyclic carbenes because the oxazole and thioazole free carbene is less stable than imidazole carbene due to less steric protection for the carbene center in the oxazole and thioazole carbenes. The novel method developed for synthesis of these heterocyclic carbene complexes includes reacting a carbene precursor salt with copper-t-butoxide to yield a cooper dichloride carbene dimer, which is then transmetallated to a metal precursor to yield heterocyclic carbene metal complexes. In particular, the method may be used to make tris heterocyclic carbene metal complexes.

(20) Heterocyclic carbene metal complexes are provided. The compounds comprise a ligand L having the structure:

(21) ##STR00022##

(22) X.sub.1 is S or O. X.sub.2, X.sub.3, X.sub.4, and X.sub.5 are independently C or N. At least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.1 may represent mono, di, tri or tetra substitutions. R.sub.1 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.1 are optionally joined to form a fused ring. R.sub.A may represent mono, di, tri, or tetra substitutions. R.sub.A is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.A are optionally joined to form a fused ring. A is a 5-membered or 6-membered carbocyclic or heterocyclic ring. Preferably, A is benzene. The ligand L is coordinated to a transition metal M having an atomic number greater than 40. Preferably, the metal M is Ir or Os. More preferably, the metal M is Ir. Additionally, the metal M is preferably Os. The bidentate ligand L may be linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

(23) In one aspect, the ligand has the formula:

(24) ##STR00023##

(25) At least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.2 may represent mono, di, tri or tetra substitutions. R.sub.2 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

(26) In another aspect, the ligand has the formula:

(27) ##STR00024##

(28) At least two of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.2 may represent mono, di, tri or tetra substitutions. R.sub.2 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

(29) In one aspect, the compound is heteroleptic. In another aspect, the compound is homoleptic. In yet another aspect, the compound has the formula:

(30) ##STR00025##

(31) Specific examples of the heterocyclic carbene compounds are provided. In one aspect, the compound is selected from the group consisting of:

(32) ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032##

(33) Each X.sub.1 is independently S or O.

(34) Additional specific examples of heterocyclic carbene compounds are provided. In one aspect, the compound is selected from the group consisting of:

(35) ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037##

(36) Additionally, a first device comprising an organic light emitting device is provided. The organic light emitting device further comprises an anode, a cathode, and an organic layer, disposed between the anode and the cathode. The organic layer comprises a compound comprising a ligand L having the structure:

(37) ##STR00038##

(38) X.sub.1 is S or O. X.sub.2, X.sub.3, X.sub.4, and X.sub.5 are independently C or N. At least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.1 may represent mono, di, tri or tetra substitutions. R.sub.1 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.1 are optionally joined to form a fused ring. R.sub.A may represent mono, di, tri, or tetra substitutions. R.sub.A is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.A are optionally joined to form a fused ring. A is a 5-membered or 6-membered carbocyclic or heterocyclic ring. Preferably, A is benzene. The ligand L is coordinated to a transition metal M having an atomic number greater than 40. Preferably, the metal M is Ir or Os. More preferably, the metal M is Os. More preferably, the metal M is Ir. The bidentate ligand may be linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

(39) In one aspect, the ligand has the formula:

(40) ##STR00039##

(41) At least one of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.2 may represent mono, di, tri or tetra substitutions. R.sub.2 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

(42) In another aspect, the ligand has the formula:

(43) ##STR00040##

(44) At least two of X.sub.2, X.sub.3, X.sub.4, and X.sub.5 is N. R.sub.2 may represent mono, di, tri or tetra substitutions. R.sub.2 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.2 are optionally joined to form a fused ring.

(45) In one aspect, the compound is heteroleptic. In another aspect, the compound is homoleptic. In yet another aspect, the homoleptic compound has the formula:

(46) ##STR00041##

(47) Specific examples of compounds that may be used in the device are provided. In one aspect, the compound is selected from the group consisting of Compound 1G-Compound 28G. Each X.sub.1 is independently S or O.

(48) In another aspect, the compound is selected from the group consisting of Compound 1-Compound 20.

(49) In one aspect, the organic layer is an emissive layer and the compound is an emissive dopant. In another aspect, the organic layer further comprises a host. Preferably, the host is a compound that comprises at least one of the chemical groups selected from the group consisting of:

(50) ##STR00042##

(51) Each of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are independently selected from the group consisting of hydrogen, deuterium, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl. k is an integer from 0 to 20. Each of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7 and X.sup.8 are independently selected from the group consisting of CH and N.

(52) In another aspect, the host is a metal complex. In yet another aspect, the metal complex is selected from the group consisting of:

(53) ##STR00043##

(54) (ON) is a bidentate ligand having metal coordinated to atoms O and N. L is an ancillary ligand. m is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

(55) In one aspect, the first device is a consumer product. In another aspect, the first device is an organic light emitting device.

(56) A process for making a carbene metal complex is also provided. The process comprises reacting the copper dichloride carbene dimer with a metal precursor to yield the carbene metal complex. In one aspect, the process further comprises reacting a carbene salt with copper-t-butoxide to yield a copper dichloride carbene dimer, prior to reacting the copper dichloride carbene dimer with the metal precursor.

(57) In one aspect, the metal is Ir, Os, Ru or Pt. In another aspect, the metal precursor is selected from the group consisting of [IrCl(COD)].sub.2, OsCl.sub.2(DMSO).sub.4, RuCl.sub.2(DMSO).sub.4, and PtCl.sub.2(SEt.sub.2).sub.2.

(58) In one aspect, the carbene metal complex has the formula:

(59) ##STR00044##

(60) X.sub.1 is NR.sub.B, S or O. In one aspect, X.sub.1 is NR.sub.B. In another aspect, X.sub.1 is S. In yet another aspect, X.sub.1 is O. X.sub.2, X.sub.3, X.sub.4, and X.sub.5 are independently C or N. R.sub.1 may represent mono, di, tri or tetra substitutions. R.sub.1 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.1 are optionally joined to form a fused ring. R.sub.A may represent mono, di, tri, or tetra substitutions. R.sub.A is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents of R.sub.A are optionally joined to form a fused ring. A is a 5-membered or 6-membered carbocyclic or heterocyclic ring. R.sub.B is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. The ligand L is coordinated to a transition metal M having an atomic number greater than 40. The bidentate ligand may be linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

(61) In one aspect, the carbene metal complex is heteroleptic. In another aspect, the carbene metal complex is homoleptic. Preferably, the carbene metal complex is tris.

(62) Combination with Other Materials

(63) The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

(64) HIL/HTL:

(65) A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but not limit to: a phthalocyanine or porphyrin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and sliane derivatives; a metal oxide derivative, such as MoO.sub.x; a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.

(66) Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:

(67) ##STR00045##

(68) Each of Ar.sup.1 to Ar.sup.9 is selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each Ar is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents are optionally joined to form a fused ring.

(69) In one aspect, Ar.sup.1 to Ar.sup.9 is independently selected from the group consisting of:

(70) ##STR00046##

(71) k is an integer from 1 to 20; X.sup.1 to X.sup.8 is CH or N; Ar.sup.1 has the same group defined above.

(72) Examples of metal complexes used in HIL or HTL include, but not limit to the following general formula:

(73) ##STR00047##

(74) M is a metal, having an atomic weight greater than 40; (Y.sup.1Y.sup.2) is a bidentate ligand, Y1 and Y.sup.2 are independently selected from C, N, O, P, and S; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and m+n is the maximum number of ligands that may be attached to the metal.

(75) In one aspect, (Y.sup.1Y.sup.2) is a 2-phenylpyridine derivative.

(76) In another aspect, (Y.sup.1Y.sup.2) is a carbene ligand.

(77) In another aspect, M is selected from Ir, Pt, Os, and Zn.

(78) In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc.sup.+/Fc couple less than about 0.6 V.

(79) Host:

(80) The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant.

(81) Examples of metal complexes used as host are preferred to have the following general formula:

(82) ##STR00048##

(83) M is a metal; (Y.sup.3Y.sup.4) is a bidentate ligand, Y.sup.3 and Y.sup.4 are independently selected from C, N, O, P, and S; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and m+n is the maximum number of ligands that may be attached to the metal.

(84) In one aspect, the metal complexes are:

(85) ##STR00049##

(86) (ON) is a bidentate ligand, having metal coordinated to atoms O and N.

(87) In another aspect, M is selected from Ir and Pt.

(88) In a further aspect, (Y.sup.3Y.sup.4) is a carbene ligand.

(89) Examples of organic compounds used as host are selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each group is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents are optionally joined to form a fused ring.

(90) In one aspect, host compound contains at least one of the following groups in the molecule:

(91) ##STR00050##

(92) R.sup.1 to R.sup.7 is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents are optionally joined to form a fused ring. When it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above.

(93) k is an integer from 0 to 20.

(94) X.sup.1 to X.sup.8 is selected from CH or N.

(95) HBL:

(96) A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED.

(97) In one aspect, compound used in HBL contains the same molecule used as host described above.

(98) In another aspect, compound used in HBL contains at least one of the following groups in the molecule:

(99) ##STR00051##

(100) k is an integer from 0 to 20; L is an ancillary ligand, m is an integer from 1 to 3.

(101) ETL:

(102) Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

(103) In one aspect, compound used in ETL contains at least one of the following groups in the molecule:

(104) ##STR00052##

(105) R.sup.1 is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. Two adjacent substituents are optionally joined to form a fused ring. When it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above.

(106) Ar.sup.1 to Ar.sup.3 has the similar definition as Ar's mentioned above.

(107) k is an integer from 0 to 20.

(108) X.sup.1 to X.sup.8 is selected from CH or N.

(109) In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:

(110) ##STR00053##

(111) (ON) or (NN) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L is an ancillary ligand; m is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

(112) In any above-mentioned compounds used in each layer of OLED device, the hydrogen atoms can be partially or fully deuterated.

(113) In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exiton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table 1 below. Table 1 lists non-limiting classes of materials, non-limiting examples of compounds for each class, and references that disclose the materials.

(114) TABLE-US-00001 TABLE 1 MATERIAL EXAMPLES OF MATERIAL PUBLICATIONS Hole injection materials Phthalocyanine and porphryin compounds Appl. Phys. Lett. 69, 2160 (1996) Starburst triarylamines J. Lumin. 72-74, 985 (1997) CF.sub.x Fluorohydrocarbon polymer Appl. Phys. Lett. 78, 673 (2001) Conducting polymers (e.g., PEDOT:PSS, polyaniline, polypthiophene) Synth. Met. 87, 171 (1997) WO2007002683 Phosphonic acid and sliane SAMs US20030162053 Triarylamine or polythiophene polymers with conductivity dopants EA01725079A1 and 0 Arylamines complexed with metal oxides such as molybdenum and tungsten oxides SID Symposium Digest, 37, 923 (2006) WO2009018009 Semiconducting organic complexes US20020158242 Metal organometallic complexes US20060240279 Cross-linkable compounds US20080220265 Hole transporting materials Triarylamines (e.g., TPD, -NPD) Appl. Phys. Lett. 51, 913 (1987) U.S. Pat. No. 5,061,569 EP650955 J. Mater. Chem. 3, 319 (1993) 0 Appl. Phys. Lett. 90, 183503 (2007) Appl. Phys. Lett. 90, 183503 (2007) Triaylamine on spirofluorene core Synth. Met. 91, 209 (1997) Arylamine carbazole compounds Adv. Mater. 6, 677 (1994), US20080124572 Triarylamine with (di)benzothiophene/ (di)benzofuran US20070278938, US20080106190 Indolocarbazoles Synth. Met. 111, 421 (2000) Isoindole compounds Chem. Mater. 15, 3148 (2003) Metal carbene complexes US20080018221 Phosphorescent OLED host materials Red hosts Arylcarbazoles Appl. Phys. Lett. 78, 1622 (2001) Metal 8-hydroxyquinolates (e.g., Alq.sub.3, BAlq) Nature 395, 151 (1998) 0 US20060202194 WO2005014551 WO2006072002 Metal phenoxybenzothiazole compounds Appl. Phys. Lett. 90, 123509 (2007) Conjugated oligomers and polymers (e.g., polyfluorene) Org. Electron. 1, 15 (2000) Aromatic fused rings WO2009066779, WO2009066778, WO2009063833, US20090045731, US20090045730, WO2009008311, US20090008605, US20090009065 Zinc complexes WO2009062578 Green hosts Arylcarbazoles Appl. Phys. Lett. 78, 1622 (2001) US20030175553 WO2001039234 Aryltriphenylene compounds 0 US20060280965 US20060280965 WO2009021126 Donor acceptor type molecules WO2008056746 Aza- carbazole/DBT/DBF JP2008074939 Polymers (e.g., PVK) Appl. Phys. Lett. 77, 2280 (2000) Spirofluorene compounds WO2004093207 Metal phenoxybenzooxazole compounds WO2005089025 WO2006132173 JP200511610 Spirofluorene- carbazole compounds 00 JP2007254297 01 JP2007254297 Indolocabazoles 02 WO2007063796 03 WO2007063754 5-member ring electron deficient heterocycles (e.g., triazole, oxadiazole) 04 J. Appl. Phys. 90, 5048 (2001) 05 WO2004107822 Tetraphenylene complexes 06 US20050112407 Metal phenoxypyridine compounds 07 WO2005030900 Metal coordination complexes (e.g., Zn, Al with N{circumflex over ()}N ligands) 08 US20040137268, US20040137267 Blue hosts Arylcarbazoles 09 Appl. Phys. Lett, 82, 2422 (2003) 0 US20070190359 Dibenzothiophene/ Dibenzofuran-carbazole compounds WO2006114966, US20090167162 US20090167162 WO2009086028 US20090030202, US20090017330 Silicon aryl compounds US20050238919 WO2009003898 Silicon/Germanium aryl compounds EP2034538A Aryl benzoyl ester WO2006100298 High triplet metal organometallic complex U.S. Pat. No. 7,154,114 Phosphorescent dopants Red dopants Heavy metal porphyrins (e.g., PtOEP) 0 Nature 395, 151 (1998) Iridium(III) organometallic complexes Appl. Phys. Lett. 78, 1622 (2001) US2006835469 US2006835469 US20060202194 US20060202194 US20070087321 US20070087321 Adv. Mater. 19, 739 (2007) WO2009100991 0 WO2008101842 Platinum(II) organometallic complexes WO2003040257 Osminum(III) complexes Chem. Mater. 17, 3532 (2005) Ruthenium(II) complexes Adv. Mater. 17, 1059 (2005) Rhenium (I), (II), and (III) complexes US20050244673 Green dopants Iridium(III) organometallic complexes Inorg. Chem. 40, 1704 (2001) and its derivatives US20020034656 U.S. Pat. No. 7,332,232 US20090108737 US20090039776 0 U.S. Pat. No. 6,921,915 U.S. Pat. No. 6,687,266 Chem. Mater. 16, 2480 (2004) US20070190359 US20060008670 JP2007123392 Adv. Mater. 16, 2003 (2004) Angew. Chem. Int. Ed. 2006, 45, 7800 WO2009050290 US20090165846 US20080015355 Monomer for polymeric metal organometallic compounds 0 U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598 Pt(II) organometallic complexes, including polydentated ligands Appl. Phys. Lett. 86, 153505 (2005) Appl. Phys. Lett. 86, 153505 (2005) Chem. Lett. 34, 592 (2005) WO2002015645 US20060263635 Cu complexes WO2009000673 Gold complexes Chem. Commun. 2906 (2005) Rhenium(III) complexes Inorg. Chem. 42, 1248 (2003) Deuterated organometallic complexes US20030138657 Organometallic complexes with two or more metal centers 0 US20030152802 U.S. Pat. No. 7,090,928 Blue dopants Iridium(III) organometallic complexes WO2002002714 WO2006009024 US20060251923 U.S. Pat. No. 7,393,599, WO2006056418, US20050260441, WO2005019373 U.S. Pat. No. 7,534,505 U.S. Pat. No. 7,445,855 US20070190359, US20080297033 U.S. Pat. No. 7,338,722 0 US20020134984 Angew. Chem. Int. Ed. 47, 1 (2008) Chem. Mater. 18, 5119 (2006) Inorg. Chem. 46, 4308 (2007) WO2005123873 WO2005123873 WO2007004380 WO2006082742 Osmium(II) complexes U.S. Pat. No. 7,279,704 Organometallics 23, 3745 (2004) Gold complexes 0 Appl. Phys. Lett. 74, 1361 (1999) Platinum(II) complexes WO2006098120, WO2006103874 Exciton/hole blocking layer materials Bathocuprine compounds (e.g., BCP, BPhen) Appl. Phys. Lett. 75, 4 (1999) Appl. Phys. Lett. 79, 449 (2001) Metal 8-hydroxyquinolates (e.g., BAlq) Appl. Phys. Lett. 81, 162 (2002) 5-member ring electron deficient heterocycles such as triazole, oxadiazole, imidazole, benzoimidazole Appl. Phys. Lett. 81, 162 (2002) Triphenylene compounds US20050025993 Fluorinated aromatic compounds Appl. Phys. Lett. 79, 156 (2001) Phenothiazine-S-oxide WO2008132085 Electron transporting materials Anthracene- benzoimidazole compounds WO2003060956 0 US20090179554 Aza triphenylene derivatives US20090115316 Anthracene- benzothiazole compounds Appl. Phys. Lett. 89, 063504 (2006) Metal 8-hydroxyquinolates (e.g., Alq.sub.3, Zrq.sub.4) Appl. Phys. Lett. 51, 913 (1987) U.S. Pat. No. 7,230,107 Metal hydroxybenoquinolates Chem. Lett. 5, 905 (1993) Bathocuprine compounds such as BCP, BPhen, etc Appl. Phys. Lett. 91, 263503 (2007) Appl. Phys. Lett. 79, 449 (2001) 5-member ring electron deficient heterocycles (e.g., triazole, oxadiazole, imidazole, benzoimidazole) Appl. Phys. Lett. 74, 865 (1999) Appl. Phys. Lett. 55, 1489 (1989) Jpn. J. Apply. Phys. 32, L917 (1993) Silole compounds 00 Org. Electron. 4, 113 (2003) Arylborane compounds 01 J. Am. Chem. Soc. 120, 9714 (1998) Fluorinated aromatic compounds 02 J. Am. Chem. Soc. 122, 1832 (2000) Fullerene (e.g., C60) 03 US20090101870 Triazine complexes 04 US20040036077 Zn (N{circumflex over ()}N) complexes 05 U.S. Pat. No. 6,528,187

EXPERIMENTAL

Compound Examples

Example 1

(115) ##STR00206##

(116) Synthesis of 2-(methylthio)-N-Phenylpyridine-3amino.

(117) ##STR00207##

(118) 3-bromo-2(methylthio)pyridine (25 g, 123 mmol), Pd.sub.2dba.sub.3 (6.75 g, 7.38 mmol), S-Phos (6.06 g, 14.77 mmol) and sodium butan-1-olate (17.74 g, 185 mmol) are placed in dry 3-neck flask under N.sub.2. The reaction mixture is vacuumed and charged with N.sub.2 a total of three times. Aniline (22.93 g, 246 mmol) and 500 mL toluene are added to the reaction mixture. The reaction mixture is refluxed for 18 h. The crude reaction mixture is run through silica gel plug and eluted with toluene. The toluene portion is concentrated down and subjected to silica gel column using 3-5% DCM in Hexane to yield the desired product.

(119) Synthesis of 3-(phenylamino)pyridine-2-thiol.

(120) ##STR00208##

(121) A 250 mL round bottom flask is charged with sodium methanethiolate (5.18 g, 73.8 mmol), 2-(methylthio)-N-Phenylpyridine-3amino (13.25 g, 61.5 mmol) and Hexamethyl phosphoramide (HMPA) (100 mL). The reaction mixture is heated up to 100 C. for 7 h. The reaction is cooled to room temperature, and 100 mL of 1N HCl is added. The reaction mixture is extracted with 3100 mL ethyl acetate. The organic portion is washed with 350 mL Brien, and then dried over sodium sulfate and evaporated to yield the desired compound.

(122) Synthesis of Benzothioazole Carbene Ligand Precursor

(123) ##STR00209##

(124) A 250 mL round bottom flask was charged with zinc dust (2.339 g, 35.8 mmol), 3-(phenylamino)pyridine-2-thiol (12 g, 59.6 mmol) and Formic Acid (100 mL). The reaction mixture is refluxed under N.sub.2 for 6 h. The reaction mixture is filtered off to get rid of insoluble material. Hypochloric acid (35.9 mL, 59.9 mmol) is added to the filtrate and stirred for 20 minutes. 200 mL of water is added and the precipitation is collected. The precipitation is washed with H.sub.2O and Ether to yield the desired product.

(125) Synthesis of Dichloro Copper Dimer

(126) ##STR00210##

(127) A 500 mL round bottom flask is charged with CuCl (3.9 g, 39.4 mmol), Lithium tert-butoxide (3.15 g, 39.4 mmol) and anhydrous THF (400 mL). The reaction mixture is stirred inside the glove box overnight. Perchloride salt (2.31 g, 7.41 mmol) is added into the reaction mixture and stirred overnight. The reaction mixture is removed from glove box and filtered. The filtrate is concentrated to dryness, and re-suspended in dichloromethane. The suspension is filtered, and the filtrate is concentrated to dryness to yield the desired compound.

(128) Synthesis of Benzothioazole Iridium Tris Complex

(129) ##STR00211##

(130) A 500 mL round bottom flask is charged with copper dichloride bridge dimer (1.68 g, 2.71 mmol), Iridium COD dimer (0.568 g, 0.846 mmol) and chlorobenzene (300 mL) to give an orange suspension. The reaction mixture is vacuumed and back filled with N.sub.2 a total of three times. Then, the reaction mixture is heated to reflux overnight. The reaction mixture is filtered, and the filtrate is concentrated to dryness. The residue is subjected to column chromatography (SiO.sub.2, 100% DCM) to yield the desired compound.

Example 2

(131) ##STR00212##

(132) Synthesis of 3-methoxy-N-phenylpyridine-2amine

(133) ##STR00213##

(134) A 1 L 3-neck flask is charged with 3-methoxypyridine-2-amine (17.65 g, 143 mmol), bromobenzene (15 g, 96 mmol), Pd.sub.2DBA.sub.3 (1.75 g, 1.91 mmol), Sodium tert-butoxide (18.36 g, 101 mmol), S-Phos (1.56 g, 3.82 mmole) and 400 mL of xylene. The reaction mixture is refluxed for 4 h. The product is isolated by column chromatography (5% EtoAc in Hexs) to yield the desired product.

(135) Synthesis of 2-(phenylamino)pyridine-3-ol

(136) ##STR00214##

(137) A 1 L 3-neck flask is charged with Pyridinium chloride (52.2 g, 452 mmol) and 3-methoxy-N-phenylpyridine-2amine (9 g, 45.2 mmol). The reaction mixture is heated to 200 C. for 4 h. The reaction mixture is dumped into 5% HCl (200 mL), and extracted with 3300 mL ETOAC. The organic portion is combined and purified by column chromatography (100% DCM) to yield the desired product.

(138) Synthesis of Benzooxoazole Carbene Ligand Precursor

(139) ##STR00215##

(140) Hydrogen tetrafluoroborate (6.79 mL, 48% w/w) is added drop-wise to a solution of 2-(phenylamino)pyridine-3-ol (9 g, 48.6 mmol) in 30 mL Methanol. After 30 minutes of stirring, the solvent is removed under vacuum and 30 mL (EtO).sub.3CH is added. The resulting solution is stirred at room temperature under N.sub.2 overnight to give a white suspension. The solid is filtered, and then washed with diethyl ether to give the product.

(141) Synthesis of Benzooxazole Iridium Tris Complex

(142) ##STR00216##

(143) For synthesis of benzooxazole iridium tris complex, please refer to the benzothioazole example.

Example 3

(144) ##STR00217## ##STR00218##

(145) Synthesis of N.sup.1,N.sup.3-bis(2-(methylthio)pyridine-3-yl)benzene-1,3-diamine

(146) ##STR00219##

(147) 3-bromo-2(methylthio)pyridine (25 g, 123 mmol), Pd.sub.2dba.sub.3 (6.75 g, 7.38 mmol), S-Phos (6.06 g, 14.77 mmole) and sodium butan-1-olate (17.74 g, 185 mmol) are placed in dry 3-neck flask under N.sub.2. The reaction mixture is vacuumed, and charged with N.sub.2 for a total of three times. 1,3-diaminobenzene (6.64 g, 61.5 mmol) and 500 mL toluene are added to the reaction mixture. The reaction mixture is refluxed for 18 h. The crude reaction mixture is run through a silica gel plug and eluted with toluene. The toluene portion is concentrated down and subjected to a silica gel column using 3-5% DCM in Hexane to yield the desired product.

(148) Synthesis of 3,3(1,3-phenylenebis(azanediyl))bis(pyridine-2-thiol)

(149) ##STR00220##

(150) A 250 ml, round bottom flask is charged with sodium methanethiolate (5.18 g, 73.8 mmol), N.sup.1,N.sup.3-bis(2-(methylthio)pyridine-3-yl)benzene-1,3-diamine (13.25 g, 61.5 mmol) and Hexamethyl phosphoramide(HMPA) (100 mL). The reaction mixture is heated up to100 C. for 7 h. The reaction is cooled to room temperature, and 100 mL of 1N HCl is added. The reaction mixture is extracted with 3100 mL ethyl acetate. The organic portion is washed with 350 mL Brien, dried over sodium sulfate and evaporated to yield the desired compound.

(151) Synthesis of 1,1-(1,3-phenylene)bis(thiazolo[5,4-b]pyridine-1-ium) Perchlorate Salt

(152) ##STR00221##

(153) A 250 mL round bottom flask is charged with zinc dust (2.339 g, 35.8 mmol), 3,3-(1,3-phenylenebis(azanediyl))bis(pyridine-2-thiol) and Formic Acid (100 mL). The reaction mixture is refluxed under N.sub.2 for 6 h. The reaction mixture is filtered off to get rid of insoluble material. Hypochloric acid (35.9 mL, 59.9 mmol) is added to the filtrate and stirred for 20 minutes. 200 mL of water is added and the precipitation is collected. The precipitation is washed with H.sub.2O and Ether to yield the desired product.

(154) Synthesis of Copper Carbene Complex

(155) ##STR00222##

(156) A 500 mL round bottom flask is charged with CuCl (3.9 g, 39.4 mmol), Lithium tert-butoxide (3.15 g, 39.4 mmol) and anhydrous THF (400 mL). The reaction mixture is stirred inside the glove box overnight. The perchloride salt (4.05 g, 7.41 mmol) is added into the reaction mixture and stirred overnight. The reaction mixture is removed from the glove box, and filtered. The filtrate is concentrated to dryness and re-suspended in dichloromethane. The suspension is filtered and filtrate is concentrated to dryness to yield the desired compound.

(157) Synthesis of Osmium Carbene Complex

(158) ##STR00223##

(159) A 250 mL round-bottomed flask is charged with OsCl.sub.2(DMSO).sub.4 (250 mg, 0.436 mmol), copper carbene complex (584 mg, 1.3 mmol) in 2-ethoxyethanol (125 mL) to give a tan suspension. The reaction mixture is vacuumed and back filled with N.sub.2; then the reaction mixture is heated to reflux for 1 h. The reaction mixture is filtered though celite, and the filtrate is subject to column chromatography (SiO.sub.2, Et.sub.3N pretreated, 60% EtOAC in hexanes) to yield the desired compound.

(160) It is understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore includes variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting.