SYNTHESIS OF MONOCYCLIC N-PYRIDYL-1, 4-AZABORINES AND THEIR PT-

COORDINATION COMPLEXES

BACKGROUND

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light-emitting devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as "saturated" colors. In particular, these standards call for saturated red, green, and blue pixels. Color may be measured using CIE coordinates, which are well known to the art.

SUMMARY

Disclosed herein in one emb a structure of formula A:

wherein X ¹ is C or N and X ² is C or N, provided that only one of X ¹ or X ² is N;

each R ¹ is independently selected from halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted aryl, optionally-substituted heteroaryl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally- substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

each of R ³ -R ⁶ is independently selected from hydrogen, deuterium, halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, optionally-substituted alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally- substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally- substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

a is 0, 1, 2, 3 or 4;

U and L" are mono, bi or tri ligands; M is a metal; x is 1, 2 or 3; b is 0, 1, or 2; c is 0 ,1 or 2; x+b+c is n, wherein n is the oxidation state of the metal M; and

ring A is pyridyl;

provided that (i) M is Pt or (ii) if M is not Pt, then R ⁴ is 2,4,6-trialkyl-substituted phenyl.

Also disclosed herein is a compound having a structure of formula C:

wherein X ¹ is C or N and X ² is C or N, provided that only one of X ¹ or X ² is N;

each R ¹ is independently selected from halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted aryl, optionally-substituted heteroaryl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally- substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

each of R ² , R ³ , R ⁵ and R ⁶ is independently selected from hydrogen, deuterium, halide, optionally- substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally- substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, optionally-substituted alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally- substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

R ⁴ is 2,4,6-trialkyl-substituted phenyl

a is 0, 1, 2, 3 or 4; and

ring A is pyridyl.

Further disclosed herein is an organic light emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a complex or compound as disclosed herein.

The foregoing will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light-emitting device.

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

FIG. 3 is a graph depicting emission and absorption data for Pt-complex 7. The PMMA data is for

Pt-complex 7-doped film with PMMA as the matrix.

FIG. 4 is a graph depicting emission and absorption data for Pt-complex 8. The PMMA data is for Pt-complex 7-doped film with PMMA as the matrix. DETAILED DESCRIPTION

Terminology As used herein, the singular terms "a," "an," and "the" include plural referents unless context clearly indicates otherwise. Also, as used herein, the term "comprises" means "includes."

Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described below. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

To facilitate review of the various examples of this disclosure, the following explanations of specific terms are provided:

"Acyl" refers to a group having the structure -C(0)R, where R may be, for example, optionally substituted alkyl, optionally substituted aryl, or optionally substituted heteroaryl. "Lower acyl" groups are those that contain one to six carbon atoms. (Ci-Ce)alkanoyl can be, for example, acetyl, propanoyl or butanoyl.

"Acyloxy" refers to a group having the structure -OC(0)R-, where R may be, for example, optionally substituted alkyl, optionally substituted aryl, or optionally substituted heteroaryl. "Lower acyloxy" groups contain one to six carbon atoms.

"Alkenyl" refers to a cyclic, branched or straight chain group containing only carbon and hydrogen, and containing one or more double bonds that may or may not be conjugated. Alkenyl groups may be unsubstituted or substituted. "Lower alkenyl" groups contain one to six carbon atoms. (C2-Ce)alkenyl can be vinyl, allyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1 - hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl.

The term "alkoxy" refers to a straight, branched or cyclic hydrocarbon configuration and combinations thereof, including from 1 to 20 carbon atoms, preferably from 1 to 6 carbon atoms (referred to as a "lower alkoxy"), more preferably from 1 to 4 carbon atoms, that includes an oxygen atom at the point of attachment. An example of an "alkoxy group" is represented by the formula -OR, where R can be an alkyl or cycloalkyl group, optionally substituted with an acyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl, halogenated alkyl, alkoxy or heterocycloalkyl group. Suitable alkoxy groups include methoxy, ethoxy, n- propoxy, i-propoxy, n4>utoxy, i4jutoxy, sec4jutoxy, tert43utoxy cyclopropoxy, cyclohexyloxy, and the like. (C ₂ -Ce)alkanoyloxy can be, for example, acetoxy, propanoyloxy, butanoyloxy, isobutanoyloxy, pentanoyloxy, or hexanoyloxy.

"Alkoxycarbonyl" refers to an alkoxy substituted carbonyl radical, -C(0)OR, wherein R represents an optionally substituted alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl or similar moiety.

(Ci-C6)alkoxycarbonyl can be, for example, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, or hexyloxycarbonyl.

The term "alkoxyaryl" refers to Ci-6alkyloxyaryl such as benzyloxy. The term "alkyl" refers to a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, w-propyl, isopropyl, w-butyl, isobutyl, i-butyl, pentyl, hexyl, heptyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like. A "lower alkyl" group is a saturated branched or unbranched hydrocarbon having from 1 to 6 carbon atoms. Preferred alkyl groups have 1 to 4 carbon atoms. Alkyl groups may be "substituted alkyls" wherein one or more hydrogen atoms are substituted with a substituent such as acyl, halogen, cycloalkyl, alkoxy, amino, hydroxyl, aryl, alkenyl, thiol, or carboxyl. For example, a lower alkyl or (Ci-Ce)alkyl can be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec -butyl, pentyl, 3-pentyl, or hexyl; (C3-C6)cycloalkyl(Ci-C6)alkyl can be cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, 2-cyclopropylethyl, 2-cyclobutylethyl, 2-cyclopentylethyl, or 2- cyclohexylethyl; halo(Ci-Ce)alkyl can be iodomethyl, bromomethyl, chloromethyl, fluoromethyl, trifluoromethyl, 2-chloroethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, or pentafluoroethyl; or hydroxy(Ci- Ce)alkyl can be hydroxymethyl, 1 -hydroxyethyl, 2-hydroxyethyl, 1 -hydroxypropyl, 2-hydroxypropyl, 3- hydroxypropyl, 1 -hydro xybutyl, 4-hydroxybutyl, 1 -hydro xypentyl, 5-hydroxypentyl, 1-hydroxyhexyl, or 6- hydroxyhexyl.

"Alkynyl" refers to a cyclic, branched or straight chain group containing only carbon and hydrogen, and containing one or more triple bonds. Alkynyl groups may be unsubstituted or substituted. "Lower alkynyl" groups are those that contain one to six carbon atoms. (C2-Ce)alkynyl can be ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1- hexynyl, 2- hexynyl, 3-hexynyl, 4-hexynyl, or 5-hexynyl.

The term "amine" or "amino" refers to a group of the formula -NRR', where R and R' can be, independently, hydrogen or an alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl, halogenated alkyl, or heterocycloalkyl group. For example, an "alkylamino" or "alkylated amino" refers to -NRR', wherein at least one of R or R' is an alkyl.

"Aminocarbonyl" alone or in combination, means an amino substituted carbonyl (carbamoyl) radical, wherein the amino radical may optionally be mono- or di-substituted, such as with alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, alkanoyl, alkoxycarbonyl, aralkoxycarbonyl and the like. An aminocarbonyl group may be -N(R)-C(0)-R (wherein R is a substituted group or H). A suitable aminocarbonyl group is acetamido.

The term "amide" or "amido" is represented by the formula -C(0)NRR', where R and R' independently can be a hydrogen, alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl, halogenated alkyl, or heterocycloalkyl group described above.

"Aryl" refers to a monovalent unsaturated aromatic carbocyclic group having a single ring (e.g., phenyl) or multiple condensed rings (e.g., naphthyl or anthryl), which can optionally be unsubstituted or substituted. A "heteroaryl group," is defined as an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group. Examples of heteroatoms include, but are not limited to, nitrogen, oxygen, sulfur, and phosphorous. Heteroaryl includes, but is not limited to, pyridinyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isooxazolyl, thiadiazolyl, oxadiazolyl, thiophenyl, furanyl, quinolinyl, isoquinolinyl, benzimidazolyl, benzooxazolyl, quinoxalinyl, and the like. The aryl or heteroaryl group can be substituted with one or more groups including, but not limited to, alkyl, alkynyl, alkenyl, aryl, halide, nitro, amino, ester, ketone, aldehyde, hydroxy, carboxylic acid, or alkoxy, or the aryl or heteroaryl group can be unsubstituted.

The term "aralkyl" or "arylalkyl" refers to an alkyl group wherein an aryl group is substituted for a hydrogen of the alkyl group. An example of an aralkyl group is a benzyl group.

"Aryloxy" or "heteroaryloxy" refers to a group of the formula -OAr, wherein Ar is an aryl group or a heteroaryl group, respectively.

"Carbocycle" refers to a carbon-based ring that includes at least three carbon atoms. A carbocycle may be, for example, a cycloalkyl, a cycloalkenyl, or an aryl group.

The term "carboxylate" or "carboxyl" refers to the group -COO ^" or -COOH.

The term "cycloalkyl" refers to a non-aromatic carbon-based ring composed of at least three carbon atoms. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. The term "heterocycloalkyl group" is a cycloalkyl group as defined above where at least one of the carbon atoms of the ring is substituted with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorous.

The term "ester" refers to a carboxyl group having the hydrogen replaced with, for example, a Ci- ₆ alkyl group ("carboxylCi- ₆ alkyl" or "alkylester"), an aryl or aralkyl group ("arylester" or "aralkylester") and so on. C0 ₂ Ci- ₃ alkyl groups are preferred, such as for example, methylester (CO ₂ Me), ethylester (COiEt) and propylester (COiPr) and includes reverse esters thereof (e.g. -OCOMe, -OCOEt and -OCOPr).

The term "halogen" or "halide" refers to fluoro, bromo, chloro and iodo substituents.

The terms 'halogenated alkyl" or "haloalkyl group" refer to an alkyl group as defined above with one or more hydrogen atoms present on these groups substituted with a halogen (F, CI, Br, I).

"Heterocycle" refers to mono or bicyclic rings or ring systems that include at least one heteroatom. The rings or ring systems generally include 1 to 9 carbon atoms in addition to the heteroatom(s) and may be saturated, unsaturated or aromatic (including pseudoaromatic). The term "pseudoaromatic" refers to a ring system which is not strictly aromatic, but which is stabilized by means of derealization of electrons and behaves in a similar manner to aromatic rings. Aromatic includes pseudoaromatic ring systems, such as pyrrolyl rings.

Examples of monocyclic heterocycle groups include, but are not limited to, those containing one nitrogen atom such as aziridine (3-membered ring), azetidine (4-membered ring), pyrrolidine

(tetrahydropyrrole), pyrroline (e.g., 3-pyrroline, 2,5-dihydropyrrole), 2H-pyrrole or 3H-pyrrole (isopyrrole, isoazole) or pyrrolidinone (5-membered rings) , piperidine, dihydropyridine, tetrahydropyridine (6- membered rings), and azepine (7-membered ring); those containing two nitrogen atoms such as imidazoline, pyrazolidine (diazolidine), imidazoline, pyrazoline (dihydropyrazole) (5-membered rings), piperazine (6- membered ring); those containing one oxygen atom such as oxirane (3-membered ring), oxetane (4- membered ring), oxolane (tetrahydrofuran), oxole (dihydrofuran) (5-membered rings), oxane (tetrahydropyran), dihydropyran, pyran (6-membered rings), oxepin (7-membered ring); those containing two oxygen atoms such as dioxolane (5-membered ring), dioxane (6-membered ring), and dioxepane (7- membered ring); those containing three oxygen atoms such as trioxane (6-membered ring); those containing one sulfur atom such as thiirane (3-membered ring), thietane (4-membered ring), thiolane

(tetrahydrothiophene) (5-membered ring), thiane (tetrahydrothiopyran) (6-membered ring), thiepane (7- membered ring); those containing one nitrogen and one oxygen atom such as tetrahydrooxazole, dihydrooxazole, tetrahydroisoxazole, dihydroisoxazole (5-membered rings), morpholine, tetrahydrooxazine, dihydrooxazine, oxazine (6-membered rings); those containing one nitrogen and one sulfur atom such as thiazoline, thiazolidine (5-membered rings), thiomorpholine (6-membered ring); those containing two nitrogen and one oxygen atom such as oxadiazine (6-membered ring); those containing one oxygen and one sulfur such as: oxathiole (5-membered ring) and oxathiane (thioxane) (6-membered ring); and those containing one nitrogen, one oxygen and one sulfur atom such as oxathiazine (6-membered ring).

Examples of 5-membered monocyclic heteroaryl groups include but are not limited to furanyl, thienyl, pyrrolyl, oxazolyl, oxadiazolyl (including 1,2,3 and 1,2,4 oxadiazolyls and furazanyl i.e. 1,2,5- oxadiazolyl), thiazolyl, isoxazolyl, isothiazolyl, pyrazolyl, imidazolyl, triazolyl (including 1,2,3, 1,2,4 and 1,3,4 triazolyls), oxatriazolyl, tetrazolyl, thiadiazolyl (including 1,2,3 and 1,3,4 thiadiazolyls) and the like.

Examples of 6-membered monocyclic heteroaryl groups include but are not limited to pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, pyranyl, oxazinyl, dioxinyl, thiazinyl, thiadiazinyl and the like. Examples of 6-membered aromatic heterocyclyls containing nitrogen include pyridyl (1 nitrogen), pyrazinyl, pyrimidinyl and pyridazinyl (2 nitrogens).

Aromatic heterocycle groups may also be bicyclic or polycyclic hetero aromatic ring systems such as fused ring systems (including purine, pteridinyl, napthyridinyl, 1H thieno[2,3-c]pyrazolyl, thieno[2,3-b]furyl and the like) or linked ring systems (such as oligothiophene, polyp yrrole and the like). Fused ring systems may also include aromatic 5-membered or 6-membered heterocycles fused to carbocyclic aromatic rings such as phenyl, naphthyl, indenyl, azulenyl, fluorenyl, anthracenyl and the like, such as 5-membered aromatic heterocycles containing nitrogen fused to phenyl rings, 5-membered aromatic heterocycles containing 1 or 2 nitrogens fused to phenyl ring.

A bicyclic heteroaryl group may be, for example, a group selected from: a) a benzene ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; b) a pyridine ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; c) a pyrimidine ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; d) a pyrrole ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; e) a pyrazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; f) an imidazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; g) an oxazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; h) an isoxazole ring fused to a 5- or 6- membered ring containing 1 or 2 ring heteroatoms; i) a thiazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; j) an isothiazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; k) a thiophene ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; I) a furan ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; m) a cyclohexyl ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; and n) a cyclopentyl ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms.

Particular examples of bicyclic heteroaryl groups containing a five membered ring fused to another five membered ring include but are not limited to imidazothiazole (e.g. imidazo[2,l-b]thiazole) and imidazoimidazole (e.g. imidazo[l,2-a]imidazole).

Particular examples of bicyclic heteroaryl groups containing a six membered ring fused to a five membered ring include but are not limited to benzofuran, benzothiophene, benzimidazole, benzoxazole, isobenzoxazole, benzisoxazole, benzothiazole, benzisothiazole, isobenzofuran, indole, isoindole, indolizine, indoline, isoindoline, purine (e.g., adenine, guanine), indazole, pyrazolopyrimidine (e.g. pyrazolo[l ,5- a] pyrimidine), benzodioxole and pyrazolopyridine (e.g. pyrazolo[l,5-a]pyridine) groups. A further example of a six membered ring fused to a five membered ring is a pyrrolopyridine group such as a pyrrolo[2,3- b] pyridine group.

Particular examples of bicyclic heteroaryl groups containing two fused six membered rings include but are not limited to quinoline, isoquinoline, chroman, thiochroman, chromene, isochromene, isochroman, benzodioxan, quinolizine, benzoxazine, benzodiazine, pyridopyridine, quinoxaline, quinazoline, cinnoline, phthalazine, naphthyridine and pteridine groups.

Examples of heteroaryl groups containing an aromatic ring and a non-aromatic ring include tetrahydronaphthalene, tetrahydroisoquinoline, tetrahydroquinoline, dihydrobenzothiophene,

dihydrobenzofuran, 2,3-dihydro- benzo[l,4]dioxine, benzo[l,3]dioxole, 4,5,6, 7-tetrahydrobenzofuran, indoiine, isoindoline and indane groups.

Examples of aromatic heterocycles fused to carbocyclic aromatic rings may therefore include but are not limited to benzothiophenyl, indolyl, isoindolyl, benzofuranyl, isobenzofuranyl, benzimidazolyl, indazolyl, benzoxazolyl, benzisoxazolyl, isobenzoxazoyl, benzothiazolyl, benzisothiazolyl, quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, cinnolinyl, benzotriazinyl, phthalazinyl, carbolinyl and the like.

Examples of 5-membered non-aromatic heterocycle rings include 2H-pyrrolyl, 1-pyrrolinyl, 2- pyrrolinyl, 3-pyrrolinyl, pyrrolidinyl, 1-pyrrolidinyl, 2-pyrrolidinyl, 3-pyrrolidinyl, tetrahydrofuranyl, tetrahydrothiophenyl, pyrazolinyl, 2-pyrazolinyl, 3-pyrazolinyl, pyrazolidinyl, 2-pyrazolidinyl, 3- pyrazolidinyl, imidazolidinyl, 3-dioxalanyl, thiazolidinyl, isoxazolidinyl, 2-imidazolinyl and the like.

Examples of 6-membered non-aromatic heterocycles include piperidinyl, piperidinonyl, pyranyl, dihydropyranyl, tetrahydropyranyl, 2H pyranyl, 4H pyranyl, thianyl, thianyl oxide, thianyl dioxide, piperazinyl, diozanyl, 1,4-dioxinyl, 1,4-dithianyl, 1,3,5-triozalanyl, 1,3,5-trithianyl, 1,4-morpholinyl, thiomorpholinyl, 1,4-oxathianyl, triazinyl, 1,4-thiazinyl and the like.

Examples of 7-membered non-aromatic heterocycles include azepanyl, oxepanyl, thiepanyl and the like.

"N-heterocyclic" refers to mono or bicyclic rings or ring systems that include at least one nitrogen heteroatom. The rings or ring systems generally include 1 to 9 carbon atoms in addition to the heteroatom(s) and may be saturated, unsaturated or aromatic (including pseudoaromatic). The term "pseudoaromatic" refers to a ring system which is not strictly aromatic, but which is stabilized by means of derealization of electrons and behaves in a similar manner to aromatic rings. Aromatic includes pseudoaromatic ring systems, such as pyrrolyl rings.

Examples of 5-membered monocyclic N-heterocycles include pyrrolyl, H-pyrrolyl, pyrrolinyl, pyrrolidinyl, oxazolyl, oxadiazolyl, (including 1,2,3 and 1,2,4 oxadiazolyls) isoxazolyl, furazanyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, imidazolyl, imidazolinyl, triazolyl (including 1,2,3 and 1,3,4 triazolyls), tetrazolyl, thiadiazolyl (including 1,2,3 and 1,3,4 thiadiazolyls), and dithiazolyl

Examples of 6-membered monocyclic N-heterocycles include pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, piperidinyl, morpholinyl, thiomorpholinyl, piperazinyl, and triazinyl. The heterocycles may be optionally substituted with a broad range of substituents, and preferably with Ci-6 alkyl, Ci-6 alkoxy, C2-6 alkenyl, C2-6 alkynyl, halo, hydroxy, mercapto, trifluoromethyl, amino, cyano or mono or di(Ci-6alkyl)amino. The N-heterocyclic group may be fused to a carbocyclic ring such as phenyl, naphthyl, indenyl, azulenyl, fluorenyl, and anthracenyl.

Examples of 8, 9 and 10-membered bicyclic heterocycles include 1H thieno[2,3-c]pyrazolyl, indolyl, isoindolyl, benzoxazolyl, benzothiazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazolyl, indazolyl, isoquinolinyl, quinolinyl, quinoxalinyl, purinyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, benzotriazinyl, and the like. These heterocycles may be optionally substituted, for example with Ci-6 alkyl, Ci-6 alkoxy, C2-6 alkenyl, C2-6 alkynyl, halo, hydroxy, mercapto, trifluoromethyl, amino, cyano or mono or di(Ci-6alkyl)amino. Unless otherwise defined optionally substituted N-heterocyclics includes pyridinium salts and the N-oxide form of suitable ring nitrogens.

The term "hydroxyl" is represented by the formula -OH.

"Isonitrile" refers to -NC.

"Nitrile" refers to -CN.

"Nitro" refers to an R-group having the structure -NO2.

As used herein, the term "organic" includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. "Small molecule" refers to any organic material that is not a polymer, and "small molecules" may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the "small molecule" class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a "small molecule," and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.

"Phosphinyl" refers to -PRR' wherein R and R' to substituted groups.

"Silyl" refers to -S1H3 or S1R3, wherein R is a substituted group. A "substituent" refers to a single atom (for example, a halogen atom) or a group of two or more atoms that are covalently bonded to each other, which are covalently bonded to an atom or atoms in a molecule to satisfy the valency requirements of the atom or atoms of the molecule, typically in place of a hydrogen atom. Examples of substituents include alkyl groups, hydroxyl groups, alkoxy groups, acyloxy groups, mercapto groups, and aryl groups.

As used herein, "solution processible" means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

"Substituted" or "substitution" refers to replacement of a hydrogen atom of a molecule or an R- group with one or more additional R-groups. Unless otherwise defined, the term "optionally substituted" or "optional substituent" as used herein refers to a group which may or may not be further substituted with 1, 2, 3, 4 or more groups, preferably 1, 2 or 3, more preferably 1 or 2 groups selected from the group consisting of Ci-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-scycloalkyl, hydroxyl, oxo, Ci-6alkoxy, aryloxy, Ci-6alkoxyaryl, halo, Ci- ₆ alkylhalo (such as CF ₃ and CHF ₂ ), Ci- ₆ alkoxyhalo (such as OCF ₃ and OCHF ₂ ), carboxyl, esters, cyano, nitro, amino, substituted amino, disubstituted amino, acyl, ketones, amides, aminoacyl, substituted amides, disubstituted amides, thiol, alkylthio, thioxo, sulfates, sulfonates, sulfinyl, substituted sulfinyl, sulfonyl, substituted sulfonyl, sulfonylamides, substituted sulfonamides, disubstituted sulfonamides, aryl, arCi-6alkyl, heterocyclyl and heteroaryl wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl and heterocyclyl and groups containing them may be further optionally substituted. Optional substituents in the case of heterocycles containing N may also include but are not limited to Ci- ₆ alkyl i.e. iV-Ci- ₃ alkyl, more preferably methyl particularly iV-methyl.

The term "sulfinyl" refers to the group -S(=0)H.

The term "substituted sulfinyl" or "sulfoxide" refers to a sulfinyl group having the hydrogen replaced with, for example a Ci- ₆ alkyl group ("Ci- ₆ alkylsulfinyl" or "Ci- ₆ alkylsulfoxide"), an aryl

("arylsulfinyl"), an aralkyl ("aralkyl sulfinyl") and so on. Ci- ₃ alkylsulfinyl groups are preferred, such as for example, -SOmethyl, -SOethyl and -SOpropyl.

The term "sulfonyl" refers to the group -SO ₂ H.

The term "substituted sulfonyl" refers to a sulfonyl group having the hydrogen replaced with, for example a Ci- ₆ alkyl group ("sulfonylCi- ₆ alkyl"), an aryl ("arylsulfonyl"), an aralkyl ("aralkylsulfonyl") and so on. SulfonylCi- ₃ alkyl groups are preferred, such as for example, -SC^Me, -SC^Et and -SC^Pr.

The term "sulfonylamido" or "sulfonamide" refers to the group -SO2NH2.

The term "sulfate" refers to the group -OS(0) ₂ 0H and includes groups having the hydrogen replaced with, for example a Ci- ₆ alkyl group ("alkylsulfates"), an aryl ("arylsulfate"), an aralkyl

("aralkylsulfate") and so on. Cusulfates are preferred, such as for example, OS(0) ₂ 0Me, OS(0) ₂ 0Et and OS(0) ₂ OPr.

The term "sulfonate" refers to the group -SO ₃ H and includes groups having the hydrogen replaced with, for example a Ci- ₆ alkyl group ("alkylsulfonate"), an aryl ("arylsulfonate"), an aralkyl

("aralkylsulfonate") and so on. Ci- ₃ sulfonates are preferred, such as for example, SOsMe, S(¾Et and SO ₃ R". The term "thioether" refers to a -S-R group, wherein R may be, for example, alkyl (including substituted alkyl), or aryl (including substituted aryl).

The term "thiol" refers to -SH. A "substituted thiol" refers to a -S-R group wherein R may be, for example, alkyl (including substituted alkyl), aryl (including substituted aryl), or halogen. For instance, a substituted thiol may be a halogenated thiol such as, for example, -SF ₅ . (Ci-Ce)alkylthio can be, for example, methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, pentylthio, or hexylthio.

The term "thioxo" refers to the group =S.

As used herein, "top" means furthest away from the substrate, while "bottom" means closest to the substrate. Where a first layer is described as "disposed over" a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is "in contact with" the second layer. For example, a cathode may be described as "disposed over" an anode, even though there are various organic layers in between.

A ligand may be referred to as "photoactive" when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as "ancillary" when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled in the art, a first "Highest Occupied Molecular Orbital" (HOMO) or "Lowest Unoccupied Molecular Orbital" (LUMO) energy level is "greater than" or "higher than" a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A "higher" HOMO or LUMO energy level appears closer to the top of such a diagram than a "lower" HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled in the art, a first work function is "greater than" or "higher than" a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a "higher" work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a "higher" work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions. Overview

Using 1 ,4-azaborine to replace the regular aromatic in the ligands for metal complexes such as Ir(2- phenylpyridine)3 offers a new avenue for novel aromatic, high triplet compounds for application in organic electronics. Novel azaborine compounds are provided that may be used as host, fluorescent emissive dopant, phosphorescent emissive dopant or charge transport materials in organic light-emitting devices. 1,4- azaborine compounds are particularly interesting heteroaromatic molecules because of the boron and nitrogen heteroatoms in the core of the compound. These 1,4-azaborine compounds can display high singlet and triplet energies due to the reduced conjugation relative to their all-carbon congeners, and they may be luminescent. Metal complexes containing 1,4-azaborine ligands may be useful as the phosphorescent emitters in PHOLEDs. Compared to their all-carbon congeners, the 1,4-azaborine analogs may show higher photophysical and electrochemical tunability because of the relatively higher polarized nature of the azaborine ring.

In certain embodiments, metal complexes containing 1,4-azaborine ligands may be useful as blue luminescent materials or high triplet charge transport materials in OLEDs. For example, the metal complexes may exhibit strong blue, Gaussian type, phosphorescence (for example, ληωχ<460 nm, PLQE>80 ). The metal complexes also can be used in phosphorescent devices, in single color or multiple color devices. In certain embodiments, the materials disclosed herein can be vapor-evaporated or solution processed.

Compounds and Complexes

One embodiment disclosed herein are metal coordination complexes of monocyclic, N-pyridyl-1,4- azaborines having the formula A:

wherein X ¹ is C or N and X ² is C or N, provided that only one of X ¹ or X ² is N;

each R ¹ is independently selected from halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted aryl, optionally-substituted heteroaryl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally- substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

each of R ³ -R ⁶ is independently selected from hydrogen, deuterium, halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, optionally-substituted alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally- substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally- substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

a is 0, 1, 2, 3 or 4;

L' and L" are mono, bi or tri ligands; M is a metal; x is 1, 2 or 3; b is 0, 1, or 2; c is 0 ,1 or 2; x+b+c is n, wherein n is the oxidation state of the metal M; and

ring A is pyridyl;

provided that (i) M is Pt or (ii) if M is not Pt, then R ⁴ is 2,4,6-trialkyl-substituted phenyl.

Ring A may be 2 -pyridyl, 3-pyridyl or 4-pyridyl. In one embodiment of ring A, ^" ""i™- is preferred. In certain embodiments, M is a second or third row transition metal. In particular embodiments, M is Pt. In comparison to Ir complexes, the Pt complexes adopt square-planar configuration around the Pt center, the electrons are more delocalized, and Pt complexes are easier to be modified.

In certain embodiments, R ⁴ may be 2,4,6-trialkyl-substituted phenyl (e.g., 2,4,6-trimethyl- phenyl (also referred to herein as mesityl (Mes) phenyl)) or R2 may be 2,4,6-triphenyl-phenyl or 2,6-diphenyl-phenyl. In general, the azaborine compounds disclosed herein are highly Lewis acidic. In order to handle them (e.g., during synthesis or use) without special care, it is necessary to protect the boron atom with bulky substituents. For example, although not bound by any theory, the 2,4,6-trimethyl- phenyl is a protecting group that may impart significantly improved stability toward air and moisture.

In certain embodiments, R ⁵ is an optionally-substituted C1-C6 alkyl, particularly methyl.

In certain embodiments, M is Pt and R ⁴ is 2,4,6-trialkyl-substituted phenyl, particularly 2,4,6- trimethyl- phenyl. In one embodiment, and L" are inde endentl selected from:

FORMULA I FORMULA IV FORMULA V FORMULA VI

FORMULA VII FORMULA VIII FORMULA IX FORMULA X

wherein each R' , R" , and R" ' is independently selected from hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, aryl, or heteroaryl; X is selected from S, NZ, O, Se, BZ, CZZ', or C=0; each Z and Z' are independently selected from hydrogen, alkyl, or aryl; and each ring A and B is independently selected from cycloalkyl, heterocycloalkyl, aryl or heteroaryl. R', R", and R'" can join to form one or more fused rings. In certain embodiments, each R', R", and R'" is independently selected from hydrogen or C ₁ -C6 alkyl.

In certain embodiments, x is 2 and b and c are each 0.

In certain embodiments, x is 1 , b is 1 and c is 0.

In certain embodiments, x is 1, b is 1 and c is 0; and U is selected from a ligand of formula IV -X. In certain embodiments the metal coordination complexes of monocyclic, N-pyridyl-l,4-azaborines have the formula B of:

wherein each of R ⁷ -R ¹⁰ is independently selected from hydrogen, deuterium, halide, optionally- substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally- substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally- substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally- substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

each of R ³ -R ⁶ is independently selected from is selected from hydrogen, deuterium, halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally- substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally- substituted heteroalkenyl, optionally-substituted alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally- substituted amido, optionally-substituted phosphoryl, optionally-substituted thiophosphoryl, optionally- substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl; and

R ³ -R ⁶ , M, L', L", x, b, and c are the same as in formula A.

Illustrative examples of the complex of formula B include:

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is ethyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-triphenyl- phenyl, R ⁵ is methyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,6-dimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, M is Pt, x is 2, and b and c are each 0; R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,4,6-triphenyl-phenyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,6-diphenyl-phenyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,4,6-triethyl-phenyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,4,6-tripropyl-phenyl, M is Pt, x is 2, and b and c are each 0;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 1, b is 1, c is 0; L' is formula V; and R' and R" are each methyl;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 1, b is 1, c is 0; L' is formula IV; and R' and R" are each methyl; R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 1, b is 1, c is 0; U is formula V; and R' and R" are each ethyl;

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 1, b is 1, c is 0; U is formula IV; and R' and R" are each ethyl;

R ³ and R ⁵ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl-phenyl, M is Pt, x is 1, b is 1, c is 0; U is formula V; and R' and R" are each methyl; or

R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, R ⁵ is methyl, M is Pt, x is 1, b is 1, c is 0; U is formula IV; and R' and R" are each methyl.

In other embodiments disclosed herein there is provided monocyclic, N-pyridyl-l,4-azaborines having the formula C:

wherein X ¹ is C or N and X ² is C or N, provided that only one of X ¹ or X ² is N;

each R ¹ is independently selected from halide, optionally-substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally-substituted arylalkyl, optionally-substituted aryl, optionally-substituted heteroaryl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally- substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl;

each of R ² , R ³ , R ⁵ and R ⁶ is independently selected from hydrogen, deuterium, halide, optionally- substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally- substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, optionally-substituted alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally-substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally-substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally- substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl; R ⁴ is 2,4,6-trialkyl-substituted phenyl

a is 0, 1, 2, 3 or 4; and

ring A is pyridyl.

In certain embodiments, R ⁵ is an optionally-substituted Ci-Ce alkyl, particularly methyl.

In certain embodiments, the monocyclic, N-pyridyl-l,4-azaborines have the formula D:

wherein each of R ⁷ -R ¹⁰ is independently selected from hydrogen, deuterium, halide, optionally- substituted alkyl, optionally-substituted cycloalkyl, optionally-substituted heterocycloalkyl, optionally- substituted arylalkyl, optionally-substituted alkoxy, optionally-substituted aryloxy, optionally-substituted amino, silyl, optionally-substituted alkenyl, optionally-substituted cycloalkenyl, optionally-substituted heteroalkenyl, alkynyl, optionally-substituted aryl, optionally-substituted heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, optionally-substituted amido, optionally- substituted phosphoryl, optionally-substituted thiophosphoryl, optionally-substituted phosphinyl, optionally- substituted thiophosphinyl, optionally-substituted thiol, nitro, azido, optionally-substituted hydrazinyl, optionally-substituted diazenyl, or thiocarbonyl; and

R ² -R ⁶ are the same as in formula C.

Illustrative examples of the complex of formula D include:

R ² , R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, and R ⁵ is methyl;

R ² , R ³ and R ⁵ -R ¹⁰ are each H, and R ⁴ is 2,4,6-trimethyl- phenyl;

R ² , R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, and R ⁵ is ethyl; or

R ² , R ³ and R ⁶ -R ¹⁰ are each H, R ⁴ is 2,4,6-trimethyl- phenyl, and R ⁵ is propyl. The 1,4-azaborines disclosed herein may be synthesized by the procedure shown in Scheme 1. In general, an acryloyl chloride is the starting compound. Curtius rearrangement of the resulting acyl azide from acyloyl chloride leads to an isocyanate; the isocyanate can be trapped by a variety of nucleophiles. In certain embodiments, the nucleophile is tert-butanol, the reaction generates Boc-protected enamine compound 1. Compound 1 undergoes N-allylation using 2,3-dibromopropene to generate a bromo- substituted N-allyl amine compound 2. Palladium-catalyzed Stille cross coupling of compound 2 with an organotin compound (e.g., hexamethylditin) to furnish the tin compound 3. Transmetallation of tin compound 3 with lithium reagent, followed by nucleophilic attaching to the boron-containing electrophile (e.g., vinylboronchloride) produces the crucial ring-closing-metathesis precursor compound 4. One pot ring- closing-metathesis/isomerization produces 1,4-azaborine, followed by methanolysis of 1,4-azaborine at the boron heteroatom and subsequent quenching with a nucleophile to produce a monocyclic 1,4-azaborine compound 5 bearing the free NH group (the Boc-protecting group was de-protected as well). Cross coupling of compound 5 with 2-bromo pyridine furnish the N-pyridinyl 1,4-azaborine 6. A specific illustration of this embodiment is described below for synthesizing ligand 6 as well as its Pt-complexes 7 and 8.

Scheme 1. Representative synthesis of Monocyclic N-pyridiyI-l,4-azaborines and Pt- coordination complexes

8

Reaction conditions: a) 1 NaN ₃ , toluene/H ₂ 0, 0 °C, 6 h; 2 i-BuOH, pyridine, hydroquinone, toluene, 85 °C, 2 h, 30%; b) NaH (1.3 equiv), 2,3-dibromopropene (1.3 equiv), DMF, 74%; c) Pd(PPh ₃ ) ₄ (20 mol%), Me ₃ SnSnMe ₃ , toluene, 110 °C, 36 h, 57%; d) «-BuLi (1.0 equiv), 1- chloro-N,N-diisopropyl-l -vinylboranamine (1.0 equiv), -78 °C to rt, 73%; e) 1. Grubbs 2 ^nd (20 mol%), toluene, 110 °C, 4 d; 2. MeOH (1.5 equiv), DCM, rt, 1 h; 3. MesLi, THF, -78 °C to rt, 33% over 3 steps; f) 2-bromopyridine, Pd ₂ dba ₃ , /-ButylXphos, NaO/Bu, toluene, 110 °C, 24 h, 73%; g) 1. Pt ₂ (SMe ₂ ) ₂ Me ₂ , THF, rt, 12 h; 2. TfOH, rt, 0.5 h; 3. Na(AcAc), THF/MeOH, rt, 1 h, 52% over 3 steps, h) Pt ₂ (SMe ₂ ) ₂ Me ₂ , THF, 110 °C, sealed tube, 2 d, 21%.

Representative procedures for the synthesis of Monocyclic N-pyridiyl-l,4-azaborines and Pt-coordination complexes

Synthesis of compound 1. A solution of acryl chloride (400 mmol, 36.2 g) and

toluene (120 ml) was added dropwise to a stirring solution of sodium azide (480 Boc mmol, 31.2 g) and H ₂ 0 (200 ml) at 0 °C. The resulting two-phase reaction NH mixture was stirred at 0 °C for 6 h, and the layers were separated. The organic

layer was washed with saturated Na ₂ C0 ₃ (2x50 ml), and dried over MgS0 ₄ in

freezer. (Caution: The solution of acryloyl azide is volatile, potentially explosive and toxic). The filtrate was added dropwise to a solution of tert-butyl alcohol (520 mmol, 38.5 g), pyridine (200 mmol, 15.8 g) and hydroquinone (22 mmol, 2.4 g) at 85 °C, during which time vigorous N ₂ evolution was observed. The resulting solution was stirred at 85 °C for 1 h, washed with saturated aqueous Na ₂ C0 ₃ (2x50 ml), dired over Na ₂ S0 ₄ and filtered. The filtrate was concentrated, and the residue was purified by distillation under attenuated pressure (60-70 °C, 0.3 Torr) provided compound 1 (16.0 g, yield = 30%) as white solid.

'H NMR (500 MHz, CD ₂ C1 ₂ ): 5D 1.45 (s, 9H, CH ₃ ), 4.18 (d, J= 6.0 Hz, 1H, =CH ₂ ), 4.42 (d, J =

15.5 Hz, 1H, =CH ₂ ), 6.41 (br, 1H, NH), 6.60-6.68 (m, 1H, CH=CH ₂ ). ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 28.6, 80.9, 92.2, 130.8, 153.3.

Synthesis of compound 2. To a solution of compound 1 (30 mmol, 4.3 g) in

DMF (70 ml) at 0 °C was added NaH (60% dispersion, 39 mmol, 1.6 g). The

mixture was stirred at 0 °C for 1 h, and then 2,3-dibromopropene (39 mmol,

7.8 g) was added. Stirring was continued for 1 h, and the reaction mixture was

partitioned between H ₂ 0 (100 ml) and ether (60 ml). The layers were

separated, and the aqueous layer was extracted with ether. The combined

organic layer was washed with H ₂ 0, dried over MgS0 ₄ , and concentrated

under reduced pressure. The resulting oil was purified by distillation under attenuated pressure (43-45 °C, 0.05 Torr) provided compound 2 (5.83 g, yield = 74%) as a colorless liquid.

¾ NMR (500 MHz, CD ₂ C1 ₂ ): δ 1.48 (s, 9H, CH ₃ ), 4.30-4.31 (m, 4H, CH ₂ ), 5.58 (d, J= 32.5 Hz, 2H, =CH ₂ ), 7.03-7.11 (m, 1H, CH=CH ₂ ). ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 28.4, 51.1, 51.7, 82.4, 92.3, 116.3, 128.0, 133.0. w z calcd for [M+H , 261.0364; found, 261.0369. Synthesis of compound 3. The mixture of compound 2 (20.5 mmol, 5.36 g), g _QC Pd(PPh ₃ ) ₄ (4.1 mmol, 4.73 g), and Me ₃ SnSnMe ₃ (30.7 mmol, 10.0 g) in ' toluene (120 ml) was heated at 110 °C under nitrogen for 36 h. After cooling

down to room temperature, the mixture was filtrated, and the solvent was

removed under vacuum. The residue was then purified by distillation under Μθ3$η attenuated pressure (55-58 °C, 0.1 Torr) to afford compound 3 (4.06 g, 57%)

as the colorless oil.

H NMR (300 MHz, CD ₂ C1 ₂ ): δ 0.19 (s, 9H, Sn(CH ₃ ) ₃ ), 4.19-4.34 (m, 4H, CH ₂ +=CH ₂ ), 5.30 (s, 1H, =CH ₂ ), 5.70 (s, 1H, =CH ₂ ), 7.08 (br, 1H, CH=CH ₂ ). m/z calcd for [M+H] ⁺ , 347.0907; found, 347.0893.

Synthesis of compound 4. The compound 3 (15.55 mmol, 5.38 g) was g _oc dissovled in ether (90 ml) under nitrogen, BuLi (15.55 mmol, 1.6 M in THF,

6.22 ml) was added slowly to the mixture at -78 °C. After additon completed,

the reaction mixture was stirred at same temperature for 0.5 hour. 1-chloro- N,N-diisopropyl-l-vinylboranamine (15.55 mmol, 2.70 g) was added at -78

°C slowly, and the reaction was continued for 1 hour at -78 °C. Then, the dry- ice bath was removed and the temperatue was allowed to room temperature

for 2 hours. The mixture was moved to golove box and filtrated through a

glass frit. After removal of the solvent, the residue was then purified by

distillation under attenuated pressure (85-90 °C, 0.1 Torr) to afford compound 4 (3.63 g, 73%) as the colorless oil.

^! H NMR (500 MHz, CD ₂ C1 ₂ ): δ 1.09 (d, J = 7.0 Hz, 6H, C¾), 1.32 (d, J = 7.0 Hz, 6H, CH ₃ ), 1.48 (s, 9H, CH ₃ ), 3.35-3.41 (m, 1H, CH), 3.99-4.18 (m, 4H, CH ₂ ), 4.23 (d, J = 15.5 Hz, 1H, CH ₂ ), 4.85 (s, 1H, CH ₂ ), 5.11-5.15 (m, 1H, CH ₂ ), 5.73 (d, J = 19.0 Hz, 1H, CH ₂ ), 5.84 (d, J = 13.0 Hz, 1H, CH ₂ ), 6.60 (dd, J _x = 14.0 Hz, J ₂ = 19.0 Hz, 1H, CH), 7.15-7.21 (m, 1H, CH). ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 22.5, 25.6, 28.6, 45.4, 49.7, 52.6, 81.2, 91.1, 91.4, 114.6, 115.5, 129.1, 129.3, 132.8, 133.1, 134.0 134.3, 140.3, 148.3, 153.0, 154.2. m/z calcd for [M+H] ⁺ , 320.2635; found, 320.2649.

Synthesis of compound 5. In a 500 ml flask equipped with a stir bar in a glove box, compound 4 (1.25 mmol, 400 mg) was dissovled in toluene (20 ml). Grubbs

Mes

2nd catalyst (0.25 mrnol, 212 mg) was dissovled in toluene (5 ml) was added quickly to the stirred solution. And the the sealed reaction flask was heated at 80 °C under N ₂ outside the golve box. The reaction was judged to be complete by ¾ NMR and ⁿ B NMR, and the solvent was removed under reduced pressure. The crude mixture was used for the following steps without further purification. In a 20 ml flask equipped with a stir bar in a glove box, above residue (0.31 mmol, 90 mg) was dissovled in dichloromethane (2 ml). Methanol (0.62 mmol, 25 μΐ) was added quickly to the stirred solution. And the reaction was stirred at room temperature for 1 h in the golve box. The solvent was removed under reduced pressure. The crude mixture was re- dissovled in THF (2 ml). And the mixture was added slowly to the stirred solution of Mes-Li in THF (0.75 mmol, freshly prepared from BuLi and Mes-Br) at -78 °C. After 2 hours, the dry-ice bath was removed, it was allowed to room temperature for another 2 hours. The reaction was qunched by water, extracted with ether. The combined organic phase was dried over MgS0 ₄ . The solvent was removed under reduced pressure. The crude mixture purified by flash chromotography (silica gel) using mixture of hexane and ethyl acetate as the eluent to afford compound 5 as white solid (yield = 33% over three steps)

¾ NMR (300 MHz, CD ₂ C1 ₂ ): δ 1.90 (s, 3H, CH ₃ ), 2.03 (s, 6H, CH ₃ ), 2.28 (s, 3H, CH ₃ ), 6.31 (dd, J = 1.8 Hz, J2 = 8.7 Hz, 1H, Ar), 6.81 (s, 2H, Ar), 7.49 (d, J= 5.4 Hz, 1H, Ar), 7.61 (dd, J _x = 5.4 Hz, J2 = 7.5 Hz, 1H, Ar), 8.44 (br, 1H, NH). ⁿ B NMR (96.2 MHz, CD ₂ C1 ₂ ): δ 45.5. ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 19.1, 21.4, 22.9, 120.1, 127.1, 131.6, 135.7, 136.5, 137.8, 138.4, 144.1

Synthesis of compound 6. To a 100 ml flask was charged with 5 (1.61 mmol, 340

mg), 2- bromopyridine (2.42 mmol, 382 mg), Pd ₂ dba ₃ (0.08 mmol, 74 mg), t- ButyXPhos (0.32 mmol, 137 mg) and NaO-tBu (3.22 mmol, 309 mg) was added

toluene (25 ml). The resulting mixture was then allowed to heat at 1 10 °C for 36 h.

After cooling down to room temperature, the solvent was removed by vacuum.

The residue was purified by flash chromatography on silica gel with hexanes/ethyl acetate as the eluent to afford compound 6 (339 mg, yield = 73%) as colorless oil.

^! H NMR (500 MHz, CD ₂ C1 ₂ ): δ 2.00 (s, 3H, CH ₃ ), 2.07 (s, 6H, CH ₃ ), 2.29 (s, 3H, CH ₃ ), 6.49 (d, J= 9.0 Hz, 1H, Ar), 6.83 (s, 2H, Ar), 7.31 (dd, J = 5.0 Hz, J ₂ = 7.5 Hz, 1H, Ar), 7.47 (d, ./= 8.0 Hz, 1H, Ar)„ 7.61 (dt, jj = 1.5 Hz, J ₂ = 8.5 Hz, 1H, Ar), 8.20 (s, 1H, Ar), . 8.29 (dd, J = 1.5 Hz, J2 = 8.5 Hz, 1H, Ar), 8.56 (dd, J _x = 1.5 Hz, J ₂ = 5.0 Hz, 1H, Ar). ⁿ B NMR (96.2 MHz, CD ₂ C1 ₂ ): δ 47.0. ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 19.5, 21.4, 22.9, 115.7, 121.4, 122.4, 127.2, 132.6, 136.0, 138.1, 138.4, 139.5, 139.6, 143.6, 149.5, 155.9.

Synthesis of compound 7. To a 20 ml flask in glovebox charged with

compound 6 (0.2 mmol, 58 mg) and Pt(SMe ₂ ) ₂ Me ₂ (0.1 mmol, 57 mg)

was added THF (2 ml). The resulting mixture was stirred at room

temperature for 12 h. After addition of TfOH (0.2 mmol, 18 μΐ), the

reaction mixture was stirred for another 0.5 h. Na(acac) (0.4 mmol, 49

mg) in MeOH (2 ml) was added and the reaction was continued to stir

at room temperature for 1 h. After removal of the solvent, the residue

was directly purified by flash chromatography on silica gel with

CH ₂ C1 ₂ /Hexanes (1 :1) as the eluent to afford compound 7 as yellow solid (60 mg, 52%).

^! H NMR (500 MHz, CD ₂ C1 ₂ ): δ 1.87 (s, 3H, CH ₃ ), 1.96 (s, 3H, CH ₃ ), 2.02 (s, 3H, CH ₃ ), 2.10 (s, 6H, CH ₃ ), 2.28 (s, 3H, CH ₃ ), 5.50 (s, 1H, CH), 6.55 (s, 1H, Ar), 6.81 (s, 2H, Ar), 7.10 (t, J= 6.0 Hz, 1H, Ar), 7.42 (d, J= 8.5 Hz, 1H, Ar), 7.89 (s, 1H, Ar), 7.99 (t, J= 9.0 Hz, 1H, Ar), 8.93 (d, J = 5.5 Hz, 1H, Ar). ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ): D δ 19.6, 21.4, 22.9, 27.5, 28.2, 103.0, 110.6, 119.2, 125.4, 127.1 , 130.5, 133.6, 135.8, 138.4, 140.2, 143.9, 146.2, 148.5, 161.1, 185.8, 187.1.

Synthesis of compound 8. To a 20 ml flask in glovebox charged with

compound 6 (0.87 mmol, 250 mg) and Pt(SMe ₂ ) ₂ Me ₂ (0.07 mmol, 42 mg) was

added THF (5 ml). The resulting mixture was stirred at room temperature for

12 h. The resulting mixture was stirred at 110 °C for 48 hours. After removal

of the solvent, the residue was directly purified by flash chromatography on

silica gel with CH ₂ Cl ₂ /ethyl acetate (10:1) as the eluent to afford compound 8

as yellow solid (12 mg, 21%).

¾ NMR (500 MHz, CD ₂ C1 ₂ ): δ 1.92 (s, 6H, CH ₃ ), 1.96 (s, 12H, CH ₃ ), 2.32 (s, 12H, CH ₃ ), 6.77 (s, 4H, Ar), 6.96 (s, 2H, Ar), 7.15 (t, J= 7.0 Hz, 2H, Ar), 7.58 (d, J = 8.5 Hz, 2H, Ar), 7.94 (t, J = 8.0 Hz, 2H, Ar), 7.98 (s, 2H, Ar), 8.66 (d, J = 5.5 Hz, 2H, Ar). ¹³ C NMR (125 MHz, CD ₂ C1 ₂ ):D δ 19.7, 21.5, 22.9, 1 12.0, 1 19.9, 127.0, 130.6, 134.8, 135.5, 136.4, 138.5, 140.2, 144.0, 146.9, 160.2, 161.4

OLEDs

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.

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.

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, pp. 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, pp. 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.

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.

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 F4-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.

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.

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.

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.

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. patent application Ser. No. 10/233,470, 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.

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 various embodiments of 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 °C. to 30 °C, and more preferably at room temperature (20-25 °C).

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.

In one embodiment, the organic layer is a blocking layer and the material having Formula A or B is a blocking material.

In another embodiment, the organic layer is an emissive layer and the material comprising Formula A or B is a host. The organic layer may further comprise an emissive dopant. In yet another aspect, the organic layer is an emissive layer and the material comprising Formula A or B is an emitter.

In one embodiment, the first device is a consumer product. In another aspect, the first device is an organic light-emitting device.

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.

HIL/HTL:

A hole injecting/transporting material to be used in various embodiments of 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 porphryin 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 silane 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. Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:

Each of Ar ¹ to Ar ⁹ is selected from 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, or selenophenodipyridine; or 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, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

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

Examples of metal complexes used in HIL or HTL include, but are not limited to the following general formula:

M is a metal, having an atomic weight greater than 40; (Y^Y ² ) is a bidentate ligand, Y ¹ and Y 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.

In one embodiment, (Y^Y ² ) is a 2-phenylpyridine derivative.

In another embodiment, (Y^Y ² ) is a carbene ligand.

In another embodiment, M is selected from Ir, Pt, Os, and Zn.

In a further embodiment, the metal complex has a smallest oxidation potential in solution vs. Fc ⁺ /Fc couple less than about 0.6 V. Host:

The light-emitting layer of the organic EL device of various embodiments 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.

Examples of metal complexes used as host are preferred to have the following general formula

M is a metal; (Y ³ -Y ⁴ ) is a bidentate ligand, Y ³ and Y 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.

In one aspect, the metal complexes are:

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

In another embodiment, M is selected from Ir and N.

In a further embodiment, (Y ³ -Y ⁴ ) is a carbene ligand.

Examples of organic compounds used as host are selected from 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, triazole, 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; or 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, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl.

In one embodiment, the host compound contains at least one of the following groups in the molecule:

wherein R ¹ to R ⁷ is independently selected from hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above; k is an integer from 0 to 20 ; and X ¹ to X ⁸ is selected from CH or N.

HBL:

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.

In one embodiment, compounds used in a HBL contain the same molecule used as a host as described above.

In another embodiment, compounds used in a HBL contain at least one of the following groups in the molecule:

wherein k is an integer from 0 to 20; L is an ancillary ligand; and m is an integer from 1 to 3. ETL:

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.

In one embodiment, compounds used in an ETL contain at least one of the following groups in the molecule

wherein R ¹ is selected from hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, heteroalkyl, aryl and heteroaryl, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above; Ar ¹ to Ar ³ has the similar definition as Ar's mentioned above; k is an integer from 0 to 20; and X ¹ to X ⁸ is selected from CH or N.

In another embodiment, the metal complexes used in ETL contain, but are not limited to the following general formula

wherein (O— N) or (N— N) 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.

More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No.

7,279,704, which is incorporated herein by reference in its entirety.

In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention.