Tetradentate platinum and palladium complex emitters containing phenyl-pyrazole and its analogues

Abstract

A phosphorescent emitter or delayed fluorescent and phosphorescent emitters represented by Formula I or Formula II, where M is platinum or palladium.

Description

TECHNICAL FIELD

The present disclosure relates to multidentate platinum and palladium compounds suitable for phosphorescent emitters and delayed fluorescent and phosphorescent emitters in display and lighting applications, and specifically to delayed fluorescent and phosphorescent or phosphorescent tetradentate metal complexes having modified emission spectra.

BACKGROUND

Compounds capable of absorbing and/or emitting light can be ideally suited for use in a wide variety of optical and electroluminescent devices, including, for example, photo-absorbing devices such as solar- and photo-sensitive devices, organic light emitting diodes (OLEDs), photo-emitting devices, or devices capable of both photo-absorption and emission and as markers for bio-applications. Much research has been devoted to the discovery and optimization of organic and organometallic materials for using in optical and electroluminescent devices. Generally, research in this area aims to accomplish a number of goals, including improvements in absorption and emission efficiency, improvements in the stability of devices, as well as improvements in processing ability.

Despite significant advances in research devoted to optical and electro-optical materials, for example, red and green phosphorescent organometallic materials are commercial, and they have been used as phosphors in organic light emitting diodes (OLEDs), lighting and advanced displays. Many currently available materials exhibit a number of disadvantages, including poor processing ability, inefficient emission or absorption, and less than ideal stability, among others.

Good blue emitters are particularly scarce, with one challenge being the stability of the blue devices. The choice of the host materials has an impact on the stability and the efficiency of the devices. The lowest triplet excited state energy of the blue phosphors is very high compared with that of the red and green phosphors, which means that the lowest triplet excited state energy of host materials for the blue devices should be even higher. Thus, one of the problems is that there are limited host materials to be used for the blue devices. Accordingly, a need exists for new materials which exhibit improved performance in optical emitting and absorbing applications.

SUMMARY

The present disclosure provides a materials design route to reduce the energy gap between the lowest triplet excited state and the lowest singlet excited state of the metal compounds to afford delayed fluorescent materials which can be an approach to solve the problems of the blue emitters.

The present disclosure relates to platinum and palladium compounds suitable as emitters in organic light emitting diodes (OLEDs), display and lighting applications.

Disclosed herein are compounds of Formula I and Formula II:

wherein M is platinum or palladium,

wherein L¹ is a five-membered heterocyclyl, heteroaryl, carbene, or N-heterocyclic carbene,

wherein each of L², L³, and L⁴ is independently a substituted or an unsubstituted aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, carbene, or N-heterocyclic carbene,

• • wherein each of F¹, F², F³, and F⁴ is independently present or absent, wherein at least one of, F¹, F², F³, and F⁴ is present, and each of F¹, F², F³, and F⁴ present is a fluorescent luminophore,
  • wherein each of A¹, A², and A is independently CH₂, CR¹R², C═O, CH₂, SiR¹R², GeH₂, GeR¹R², NH, NR³, PH, PR³, R³P═O, AsR³, R³As═O, O, S, S═O, SO₂, Se, Se═O, SeO₂, BH, BR³, R³Bi═O, BiH, or BiR³,
  • wherein each of V¹, V², V³, and V⁴ is coordinated with M and is independently N, C, P, B, or Si,
  • wherein each of Y¹, Y², Y³, and Y⁴ is independently C, N, O, S, S═O, SO₂, Se, Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O, or BR³,
  • wherein R^a is present or absent, wherein R^b is present or absent, wherein R^c is present or absent, wherein R^d is present or absent, and if present each of R^a, R^b, R^c, and R^d independently represents mono-, di-, or tri-substitutions, and wherein each of R^a, R^b, R^c, and R^d is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof, and
  • wherein each of R¹, R², and R³ is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

Also disclosed herein are compositions comprising one or more compounds disclosed herein.

Also disclosed herein are devices, such as OLEDs, comprising one or more compounds or compositions disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a Jablonski Energy Diagram, which shows the emission pathways of fluorescence, phosphorescence, and delayed fluorescence. The energy difference between the lowest triplet excited state (T₁) and the lowest singlet excited state (S₁) is Δ E_ST. When Δ E_ST becomes small enough, efficient intersystem crossing (ISC) from lowest triplet excited state (T₁) to lowest singlet excited state (S₁) can occur. In such situations, the excitons undergo non-radiative relaxation via ISC from T₁ to S₁, and then further relaxation from S₁ to S₀, commonly known as delayed fluorescence.

FIG. 2 depicts a device including a metal complex as disclosed herein.

FIG. 3 shows emission spectra of PtON1a in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 4 shows emission spectra of PtON1a-tBu in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 5 shows EL spectra for the devices of ITO/HATCN (10 nm)/NPD (40 nm)/TAPC (10 nm)/26mCPy: 6% PtON1a-tBu/DPPS (10 nm)/BmPyPB (40 nm)/LiF/AL.

FIG. 6 shows external quantum efficiency (% photon/electron) vs. current density (mA/cm²) for the devices of ITO/HATCN (10 nm)/NPD (40 nm)/TAPC (10 nm)/26mCPy: 6% PtON1a-tBu/DPPS (10 nm)/BmPyPB (40 nm)/LiF/AL.

FIG. 7 shows emission spectra of PtOO1a at room temperature in CH₂Cl₂ and at 77K in 2-methyltetrahydrofuran, in accordance with various aspects of the present disclosure.

FIG. 8 shows emission spectra of PtON1b in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 9 shows emission spectra of PtON1aMe in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 10 shows emission spectra of PtOO1aMe in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 11 shows emission spectra of Pt1aO1Me in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 12 shows emission spectra of PdON1a in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 13 shows emission spectra of PdON1b in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

FIG. 14 shows emission spectrum of PdOO1aMe at 77K, in accordance with various aspects of the present disclosure.

FIG. 15 shows emission spectra of Pd1aO1Me in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference to the following detailed description and the Examples included therein.

Before the present compounds, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing, example methods and materials are now described.

As used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component” includes mixtures of two or more components.

As used herein, the terms “optional” and “optionally” mean that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

Disclosed are the components to be used to prepare the compositions described herein as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E. B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods.

As referred to herein, a linking atom or group connects two atoms such as, for example, a N atom and a C atom. A linking atom or group is in one aspect disclosed as X. Y, or Z herein. The linking atom or group can optionally, if valency permits, have other chemical moieties attached. For example, in one aspect, an oxygen would not have any other chemical groups attached as the valency is satisfied once it is bonded to two groups (e.g., N and/or C groups). In another aspect, when carbon is the linking atom, two additional chemical moieties can be attached to the carbon. Suitable chemical moieties amine, amide, thiol, aryl, heteroaryl, cycloalkyl, and heterocyclyl.

The term “cyclic structure” or the like terms used herein refer to any cyclic chemical structure which includes, but is not limited to, aryl, heteroaryl, cycloalkyl, cycloalkenyl, heterocyclyl, carbene, and N-heterocyclic carbene.

As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described below. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, the heteroatoms, such as nitrogen, can have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. This disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Also, the terms “substitution” or “substituted with” include the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., a compound that does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. It is also contemplated that, in certain aspects, unless expressly indicated to the contrary, individual substituents can be further optionally substituted (i.e., further substituted or unsubstituted).

In defining various terms, “A¹,” “A²,” “A³,” and “A⁴” are used herein as generic symbols to represent various specific substituents. These symbols can be any substituent, not limited to those disclosed herein, and when they are defined to be certain substituents in one instance, they can, in another instance, be defined as some other substituents.

The term “alkyl” as used herein is a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. The alkyl group can be cyclic or acyclic. The alkyl group can be branched or unbranched. The alkyl group can also be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol, as described herein. A “lower alkyl” group is an alkyl group containing from one to six (e.g., from one to four) carbon atoms.

Throughout the specification “alkyl” is generally used to refer to both unsubstituted alkyl groups and substituted alkyl groups; however, substituted alkyl groups are also specifically referred to herein by identifying the specific substituent(s) on the alkyl group. For example, the term “halogenated alkyl” or “haloalkyl” specifically refers to an alkyl group that is substituted with one or more halide, e.g., fluorine, chlorine, bromine, or iodine. The term “alkoxyalkyl” specifically refers to an alkyl group that is substituted with one or more alkoxy groups, as described below. The term “alkylamino” specifically refers to an alkyl group that is substituted with one or more amino groups, as described below, and the like. When “alkyl” is used in one instance and a specific term such as “alkylalcohol” is used in another, it is not meant to imply that the term “alkyl” does not also refer to specific terms such as “alkylalcohol” and the like.

This practice is also used for other groups described herein. That is, while a term such as “cycloalkyl” refers to both unsubstituted and substituted cycloalkyl moieties, the substituted moieties can, in addition, be specifically identified herein; for example, a particular substituted cycloalkyl can be referred to as, e.g., an “alkylcycloalkyl.” Similarly, a substituted alkoxy can be specifically referred to as, e.g., a “halogenated alkoxy,” a particular substituted alkenyl can be, e.g., an “alkenylalcohol,” and the like. Again, the practice of using a general term, such as “cycloalkyl,” and a specific term, such as “alkylcycloalkyl,” is not meant to imply that the general term does not also include the specific term.

The term “cycloalkyl” as used herein is 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, norbornyl, and the like. The term “heterocycloalkyl” is a type of cycloalkyl group as defined above, and is included within the meaning of the term “cycloalkyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkyl group and heterocycloalkyl group can be substituted or unsubstituted. The cycloalkyl group and heterocycloalkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “polyalkylene group” as used herein is a group having two or more CH₂ groups linked to one another. The polyalkylene group can be represented by the formula —(CH₂)_a—, where “a” is an integer of from 2 to 500.

The terms “alkoxy” and “alkoxyl” as used herein to refer to an alkyl or cycloalkyl group bonded through an ether linkage; that is, an “alkoxy” group can be defined as —OA¹ where A¹ is alkyl or cycloalkyl as defined above. “Alkoxy” also includes polymers of alkoxy groups as just described; that is, an alkoxy can be a polyether such as —OA¹-OA² or —OA¹-(OA²)_a-OA³, where “a” is an integer of from 1 to 200 and A¹, A², and A³ are alkyl and/or cycloalkyl groups.

The term “alkenyl” as used herein is a hydrocarbon group of from 2 to 24 carbon atoms with a structural formula containing at least one carbon-carbon double bond. Asymmetric structures such as (A¹A²)C═C(A³A⁴) are intended to include both the E and Z isomers. This can be presumed in structural formulae herein wherein an asymmetric alkene is present, or it can be explicitly indicated by the bond symbol C═C. The alkenyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

The term “cycloalkenyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms and containing at least one carbon-carbon double bound, i.e., C═C. Examples of cycloalkenyl groups include, but are not limited to, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, cyclohexadienyl, norbornenyl, and the like. The term “heterocycloalkenyl” is a type of cycloalkenyl group as defined above, and is included within the meaning of the term “cycloalkenyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkenyl group and heterocycloalkenyl group can be substituted or unsubstituted. The cycloalkenyl group and heterocycloalkenyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “alkynyl” as used herein is a hydrocarbon group of 2 to 24 carbon atoms with a structural formula containing at least one carbon-carbon triple bond. The alkynyl group can be unsubstituted or substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

The term “cycloalkynyl” as used herein is a non-aromatic carbon-based ring composed of at least seven carbon atoms and containing at least one carbon-carbon triple bound. Examples of cycloalkynyl groups include, but are not limited to, cycloheptynyl, cyclooctynyl, cyclononynyl, and the like. The term “heterocycloalkynyl” is a type of cycloalkenyl group as defined above, and is included within the meaning of the term “cycloalkynyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkynyl group and heterocycloalkynyl group can be substituted or unsubstituted. The cycloalkynyl group and heterocycloalkynyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “aryl” as used herein is a group that contains any carbon-based aromatic group including, but not limited to, benzene, naphthalene, phenyl, biphenyl, phenoxybenzene, and the like. The term “aryl” also includes “heteroaryl,” which is defined as a group that contains 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 phosphorus. Likewise, the term “non-heteroaryl.” which is also included in the term “aryl,” defines a group that contains an aromatic group that does not contain a heteroatom. The aryl group can be substituted or unsubstituted. The aryl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein. The term “biaryl” is a specific type of aryl group and is included in the definition of “aryl.” Biaryl refers to two aryl groups that are bound together via a fused ring structure, as in naphthalene, or are attached via one or more carbon-carbon bonds, as in biphenyl.

The term “aldehyde” as used herein is represented by the formula —C(O)H. Throughout this specification “C(O)” is a short hand notation for a carbonyl group, i.e., C═O.

The terms “amine” or “amino” as used herein are represented by the formula —NA¹A², where A¹ and A² can be, independently, hydrogen or alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “alkylamino” as used herein is represented by the formula —NH(-alkyl) where alkyl is a described herein. Representative examples include, but are not limited to, methylamino group, ethylamino group, propylamino group, isopropylamino group, butylamino group, isobutylamino group, (sec-butyl)amino group, (tert-butyl)amino group, pentylamino group, isopentylamino group, (tert-pentyl)amino group, hexylamino group, and the like.

The term “dialkylamino” as used herein is represented by the formula —N(-alkyl)₂ where alkyl is a described herein. Representative examples include, but are not limited to, dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di(sec-butyl)amino group, di(tert-butyl)amino group, dipentylamino group, diisopentylamino group, di(tert-pentyl)amino group, dihexylamino group, N-ethyl-N-methylamino group, N-methyl-N-propylamino group, N-ethyl-N-propylamino group and the like.

The term “carboxylic acid” as used herein is represented by the formula —C(O)OH.

The term “ester” as used herein is represented by the formula —OC(O)A¹ or —C(O)OA¹, where A¹ can be alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. The term “polyester” as used herein is represented by the formula -(A¹O(O)C-A²-C(O)O)_a— or -(A¹O(O)C-A²-OC(O))_a—, where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein and “a” is an integer from 1 to 500. “Polyester” is as the term used to describe a group that is produced by the reaction between a compound having at least two carboxylic acid groups with a compound having at least two hydroxyl groups.

The term “ether” as used herein is represented by the formula A¹OA², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein. The term “polyether” as used herein is represented by the formula -(A¹O-A²O)_a—, where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein and “a” is an integer of from 1 to 500. Examples of polyether groups include polyethylene oxide, polypropylene oxide, and polybutylene oxide.

The term “polymeric” includes polyalkylene, polyether, polyester, and other groups with repeating units, such as, but not limited to —(CH₂O)_n—CH₃, —(CH₂CH₂O)_n—CH₃, —[CH₂CH(CH₃)]_n—CH₃, —[CH₂CH(COOCH₃)]_n—CH₃, —[CH₂CH(COOCH₂CH₃)]_n—CH₃, and —[CH₂CH(COO^tBu)]_n—CH₃, where n is an integer (e.g., n>1 or n>2).

The term “halide” as used herein refers to the halogens fluorine, chlorine, bromine, and iodine.

The term “heterocyclyl,” as used herein refers to single and multi-cyclic non-aromatic ring systems and “heteroaryl as used herein refers to single and multi-cyclic aromatic ring systems: in which at least one of the ring members is other than carbon. The terms includes azetidine, dioxane, furan, imidazole, isothiazole, isoxazole, morpholine, oxazole, oxazole, including, 1,2,3-oxadiazole, 1,2,5-oxadiazole and 1,3,4-oxadiazole, piperazine, piperidine, pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole, pyrrolidine, tetrahydrofuran, tetrahydropyran, tetrazine, including 1,2,4,5-tetrazine, tetrazole, including 1,2,3,4-tetrazole and 1,2,4,5-tetrazole, thiadiazole, including, 1,2,3-thiadiazole, 1,2,5-thiadiazole, and 1,3,4-thiadiazole, thiazole, thiophene, triazine, including 1,3,5-triazine and 1,2,4-triazine, triazole, including, 1,2,3-triazole, 1,3,4-triazole, and the like.

The term “hydroxyl” as used herein is represented by the formula —OH.

The term “ketone” as used herein is represented by the formula A¹C(O)A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “azide” as used herein is represented by the formula —N₃.

The term “nitro” as used herein is represented by the formula —NO₂.

The term “nitrile” as used herein is represented by the formula —CN.

The term “silyl” as used herein is represented by the formula —SiA¹A²A³, where A¹, A², and A³ can be, independently, hydrogen or an alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “sulfo-oxo” as used herein is represented by the formulas —S(O)A¹, —S(O)₂A¹, —OS(O)₂A¹, or —OS(O)₂OA¹, where A¹ can be hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. Throughout this specification “S(O)” is a short hand notation for S═O. The term “sulfonyl” is used herein to refer to the sulfo-oxo group represented by the formula —S(O)₂A¹, where A¹ can be hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. The term “sulfone” as used herein is represented by the formula A'S(O)₂A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. The term “sulfoxide” as used herein is represented by the formula A¹S(O)A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “thiol” as used herein is represented by the formula —SH.

“R,” “R¹,” “R²,” “R³,” “Rⁿ,” where n is an integer, as used herein can, independently, possess one or more of the groups listed above. For example, if R¹ is a straight chain alkyl group, one of the hydrogen atoms of the alkyl group can optionally be substituted with a hydroxyl group, an alkoxy group, an alkyl group, a halide, and the like. Depending upon the groups that are selected, a first group can be incorporated within second group or, alternatively, the first group can be pendant (i.e., attached) to the second group. For example, with the phrase “an alkyl group comprising an amino group,” the amino group can be incorporated within the backbone of the alkyl group. Alternatively, the amino group can be attached to the backbone of the alkyl group. The nature of the group(s) that is (are) selected will determine if the first group is embedded or attached to the second group.

Compounds described herein may contain “optionally substituted” moieties. In general, the term “substituted,” whether preceded by the term “optionally” or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent. Unless otherwise indicated, an “optionally substituted” group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position. Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds. In is also contemplated that, in certain aspects, unless expressly indicated to the contrary, individual substituents can be further optionally substituted (i.e., further substituted or unsubstituted).

In some aspects, a structure of a compound can be represented by a formula:

which is understood to be equivalent to a formula:

wherein n is typically an integer. That is, Rⁿ is understood to represent five independent substituents, R^n(a), R^n(b), R^n(c), R^n(d), R^n(e). By “independent substituents,” it is meant that each R substituent can be independently defined. For example, if in one instance R^n(a) is halogen, then R^n(b) is not necessarily halogen in that instance.

Several references to R, R¹, R², R³, R⁴, R⁵, R⁶, etc. are made in chemical structures and moieties disclosed and described herein. Any description of R, R¹, R², R³, R⁴, R⁵, R⁶, etc. in the specification is applicable to any structure or moiety reciting R, R¹, R², R³, R⁴, R⁵, R⁶, etc. respectively.

1. Compounds

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.

Excitons decay from singlet excited states to ground state to yield prompt luminescence, which is fluorescence. Excitons decay from triplet excited states to ground state to generate luminescence, which is phosphorescence. Because the strong spin-orbit coupling of the heavy metal atom enhances intersystem crossing (ISC) very efficiently between singlet and triplet excited states, phosphorescent metal complexes, such as platinum complexes, have demonstrated their potential to harvest both the singlet and triplet excitons to achieve 100% internal quantum efficiency. Thus phosphorescent metal complexes are good dopants in the emissive layer of organic light emitting devices (OLEDs). Much achievement has been made in the past decade to lead to the lucrative commercialization of the technology, for example, OLEDs have been used in advanced displays in smart phones, televisions, and digital cameras.

However, to date, blue electroluminescent devices remain the most challenging area of this technology, due at least in part to instability of the blue devices. It is generally understood that the choice of host materials is a factor in the stability of the blue devices. But the lowest triplet excited state (T₁) energy of the blue phosphors is high, which generally means that the lowest triplet excited state (T₁) energy of host materials for the blue devices should be even higher. This leads to difficulty in the development of the host materials for the blue devices.

This disclosure provides a materials design route by introducing fluorescent luminophore(s) to the ligand of the metal complexes. Thereby chemical structures of the fluorescent luminophores and the ligands may be modified, and also the metal may be changed to adjust the singlet states energy and the triplet states energy of the metal complexes, which all may affect the optical properties of the complexes, for example, emission and absorption spectra. Accordingly, the energy gap (Δ E_ST) between the lowest triplet excited state (T₁) and the lowest singlet excited state (S₁) may be also adjusted. When the Δ E_ST becomes small enough, intersystem crossing (ISC) from the lowest triplet excited state (T₁) to the lowest singlet excited state (S₁) may occur efficiently, such that the excitons undergo non-radiative relaxation via ISC from T₁ to S₁, then relax from S₁ to S₀, which leads to delayed fluorescence, as depicted in the Jablonski Energy Diagram in FIG. 1. Through this pathway, higher energy excitons may be obtained from lower excited state (from T₁→S₁), which means more host materials may be available for the dopants. This approach offers a solution to problems associated with blue devices.

For example, when fluorescent luminophore fluorene in PtON1b was changed to biphenyl in PtON1a, triplet excited state (T₁) energy was increased (1240/476=2.605 eV nm in PtON1b and 1240/472=2.627 eV in PtON1a). However, the singlet excited state (S₁) energy was still nearly the same, so the energy gap (Δ E_ST) decreased, as can been seen in FIGS. 2 and 8. Thus, the complex undergoes intersystem crossing (ISC) more efficiently, resulting in a larger (S₁→S₀) delayed fluorescent peak in PtON1a.

The metal complexes described herein can be tailored or tuned to a specific application that desires a particular emission or absorption characteristic. The optical properties of the metal complexes in this disclosure can be tuned by varying the structure of the ligand surrounding the metal center or varying the structure of fluorescent luminophore(s) on the ligands. For example, the metal complexes having a ligand with electron donating substituents or electron withdrawing substituents can be generally exhibit different optical properties, including emission and absorption spectra. The color of the metal complexes can be tuned by modifying the conjugated groups on the fluorescent luminophores and ligands.

The emission of these complexes can be tuned, for example, from the ultraviolet to near-infrared, by, for example, modifying the ligand or fluorescent luminophore structure. A fluorescent luminophore is a group of atoms in an organic molecule, which can absorb energy to generate singlet excited state(s), the singlet exciton(s) produce(s) decay rapidly to yield prompt luminescence. In another aspect, the complexes can provide emission over a majority of the visible spectrum. In a specific example, the complexes can emit light over a range of from about 400 nm to about 700 nm. In another aspect, the complexes have improved stability and efficiency over traditional emission complexes. In yet another aspect, the complexes can be useful as luminescent labels in, for example, bio-applications, anti-cancer agents, emitters in organic light emitting diodes (OLED), or a combination thereof. In another aspect, the complexes can be useful in light emitting devices, such as, for example, compact fluorescent lamps (CFL), light emitting diodes (LED), incandescent lamps, and combinations thereof.

Disclosed herein are compounds or compound complexes comprising platinum and palladium. The terms compound or compound complex are used interchangeably herein. In one aspect, the compounds discloses herein have a neutral charge.

The compounds disclosed herein, can exhibit desirable properties and have emission and/or absorption spectra that can be tuned via the selection of appropriate ligands. In another aspect, the present invention can exclude any one or more of the compounds, structures, or portions thereof, specifically recited herein.

The compounds disclosed herein are suited for use in a wide variety of optical and electro-optical devices, including, but not limited to, photo-absorbing devices such as solar- and photo-sensitive devices, organic light emitting diodes (OLEDs), photo-emitting devices, or devices capable of both photo-absorption and emission and as markers for bio-applications.

As briefly described above, the disclosed compounds are platinum and palladium complexes. In one aspect, the compounds disclosed herein can be used as host materials for OLED applications, such as full color displays.

The compounds disclosed herein are useful in a variety of applications. As light emitting materials, the compounds can be useful in organic light emitting diodes (OLEDs), luminescent devices and displays, and other light emitting devices.

In another aspect, the compounds can provide improved efficiency, improved operational lifetimes, or both in lighting devices, such as, for example, organic light emitting devices, as compared to conventional materials.

These compounds can be made using a variety of methods, including, but not limited to those recited in the examples provided herein.

The compounds disclosed herein can be delayed fluorescent emitters, delayed phosphorescent emitters, or both. In one aspect, the compounds disclosed herein can be a delayed fluorescent emitter. In another aspect, the compounds disclosed herein can be a phosphorescent emitter. In yet another aspect, the compounds disclosed herein can be a delayed fluorescent emitter and a phosphorescent emitter.

Disclosed herein are compounds of Formula I and Formula II:

wherein M is platinum or palladium,

wherein L¹ is a five-membered heterocyclyl, heteroaryl, carbene, or N-heterocyclic carbene,

wherein each of L², L³, and L⁴ is independently a substituted or an unsubstituted aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, carbene, or N-heterocyclic carbene,

wherein each of F¹, F², F³, and F⁴ is independently present or absent, wherein at least one of F¹, F², F³, and F⁴ is present, and each of F¹, F², F³, and F⁴ present is a fluorescent luminophore,

wherein each of A¹, A², and A is independently CH₂, CR¹R², C═O, CH₂, SiR¹R², GeH₂, GeR¹R², NH, NR³, PH, PR³, R³P═O, AsR³, R³As═O, O, S, S═O, SO₂, Se, Se═O, SeO₂, BH, BR³, R³Bi═O, BiH, or BiR³,

wherein each of V¹, V², V³, and V⁴ is coordinated with M and is independently N, C, P, B, or Si,

wherein each of Y¹, Y², Y³, and Y⁴ is independently C, N, O, S, S═O, SO₂, Se, Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O, or BR³,

wherein R^a is present or absent, wherein R^b is present or absent, wherein R^c is present or absent, wherein R^d is present or absent, and if present each of R^a, R^b, R^c, and R^d independently represents mono-, di-, or tri-substitutions, and wherein each of R^a, R^b, R^c, and R^d is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof, and

wherein each of R¹, R², and R³ is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In one aspect, the wherein the compound is represented by the structure of Formula III, Formula IV, Formula V, or Formula VI:

wherein each of R^e and R^f is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In another aspect, the compound can have the structure of Formula VII or Formula VIII:

wherein R^e and R^f are on the ortho-positions of the bond between F¹ and L¹,

wherein R^g and R^h are on the ortho-positions of the bond between F² and L²,

wherein Rⁱ and R^j are on the ortho-positions of the bond between F³ and L³,

wherein R^k and R^l are on the ortho-positions of the bond between F⁴ and L⁴,

wherein each of R^e, R^f, R^g, R^h, Rⁱ, R^j, R^k, and R^l is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric, or any conjugate or combination thereof.

In yet another aspect, the compound can have any one of Formulas A1-A23:

wherein each of X, X¹, and X² is independently selected from N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, and Bi═O,

• • wherein each of Z, Z¹, and Z² is independently a linking atom or group,
  • wherein R^x is present or absent, wherein R^y is present or absent, and if present each of R^x and R^y independently represents mono-, di-, or tri-substitutions, and wherein each of R^x and R^y is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In yet another aspect, the compound can have any one of the structures of Formula A-24 or asymmetrical Formulas A-25 through A-36:

wherein each of Y⁵, Y⁶, Y⁷, and Y⁸ is independently C, N, O, S, S═O, SO₂, Se, Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O or BR³,

wherein X is selected from N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, and Bi═O,

wherein Z is a linking atom or group,

wherein R^x is present or absent, wherein R^y is present or absent, wherein R^z is present or absent, and if present each of R^x, R^y, and R^z independently represents mono-, di-, or tri-substitutions, and wherein each of R^x, R^y, and R^z is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

A. M Groups

In one aspect, M is Pt.

In another aspect, M is Pd.

B. A Groups

In one aspect, each of A¹, A², and A is independently CH₂, CR¹R², C═O, SiR¹R², GeH₂, GeR¹R², NH, NR³, PH, PR³, R³P═O, AsR³, R³As═O, O, S, S═O, SO₂, Se, Se═O, SeO₂, BH, BR³, R¹Bi═O, BiH, or BiR³.

In another aspect, each of A¹, A², and A is independently O, S, or CH₂.

C. Z Groups

In one aspect, for any of the formulas disclosed herein, each of

and

(also denoted as Z. Z¹, and Z² herein) is independently one of the following structures:

wherein n is an integer from 0 to 4,

wherein m is an integer from 1 to 3,

wherein each of R, R¹, R², R³, and R⁴ is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In one aspect, n is 0. In another aspect, n is 1. In yet another aspect, n is 2. In yet another aspect, n is 3. In yet another aspect, n is 4.

In one aspect, m is 1. In another aspect, m is 2. In yet another aspect, m is 3.

In one aspect, each of R, R¹, R², R³, and R⁴ is independently hydrogen, halogen, hydroxyl, thiol, or independently substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, or amino.

D. L Groups

In one aspect, L¹ is a five-membered heterocyclyl, heteroaryl, carbene, or N-heterocyclic carbene.

In one aspect, L² is aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, carbene, or N-heterocyclic carbene. In one example, L² is aryl, cycloalkyl, cycloalkenyl, heteroaryl, or N-heterocyclyl. In another example, L² is aryl or heteroaryl. In yet another example, L² is aryl. In one aspect, L² has the structure

for example,

In another aspect, L² has the structure

for example,

In another aspect, L² has the structure

for example,

In another aspect, L² has the structure

wherein each R, R¹ and R² is independently hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, halogen, hydroxyl, amino, or thiol. In one aspect, V² is N, C, P, B, or Si. In one example, V² is N or C. Wherein each of V¹ and V² is coordinated with M and is independently N, C, P, B, or Si. Wherein X is selected from N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, and Bi═O. Y is C, N, O, S. S═O, SO₂, Se, Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O, or BR³. Each of Z, Z¹, and Z² is independently a linking atom or group.

In one aspect, L³ is aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, carbene, or N-heterocyclic carbene. In one example, L³ is aryl, cycloalkyl, cycloalkenyl, heteroaryl, or heterocyclyl. In another example, L³ is aryl or heteroaryl. In yet another example, L³ is aryl. In one aspect, L³ has the structure

for example,

In another aspect, L³ has the structure

for example,

In another aspect, L³ has the structure

for example,

or wherein each R, R¹ and R² is independently hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, halogen, hydroxyl, amino, or thiol. In one aspect, V³ is N, C, P, B, or Si. In one example, V³ is N or C. Each of V¹ and V² is coordinated with M and is independently N, C, P, B, or Si. X is selected from N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, and Bi═O. Y is C, N, O, S, S═O, SO₂, Se. Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O, or BR³. Each of Z, Z¹, and Z¹ is independently a linking atom or group.

In one aspect, L⁴ is aryl, cycloalkyl, cycloalkenyl, heteroaryl, heterocyclyl, carbene, or N-heterocyclic carbene. In one example, L⁴ is aryl, cycloalkyl, cycloalkenyl, heteroaryl, or heterocyclyl. In another example, L⁴ is aryl or heteroaryl. In yet another example, L⁴ is heteroaryl. In yet another example, L⁴ is heterocyclyl. It is understood that V⁴ can be a part of L⁴ and is intended to be included the description of L⁴ above. In one aspect, L⁴ has the structure

for example,

In yet another aspect, L⁴ can has structure

for example,

In yet another aspect, L⁴ has the structure

for example,

In yet another aspect, L⁴ has the structure

In yet another aspect, L⁴ has the structure

In one aspect, V⁴ is N, C, P, B, or Si. In one example, V⁴ is N or C. Each of Y⁶, and Y⁷ is independently C, N, O, S, S═O, SO₂, Se, Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O or BR³.

In one aspect, for any of the formulas disclosed herein, five-membered heterocylyl

may represent one or more of the following structures:

It is understood that one or more of R^a, R^b, R^c, and R^d as described herein may be bonded to

as permitted by valency.

In one aspect,

has the structure

In one aspect, for any of the formulas illustrated in this disclosure, each of

independently has one of the following structures:

wherein R is hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In one aspect,

In one aspect,

In another aspect,

In one aspect, for any of the formulas disclosed herein, each of

is independently one of the following structures:

wherein R is hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In one aspect, for any of the formulas illustrated in this disclosure, each of

is independently one of the following structures:

wherein R hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted aryl, cycloalkl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alknyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

E. Fluorescent Luminophore Groups

In one aspect, any one more of F¹, F², F³, and F⁴ is present. In another aspect, F¹ is present and F², F³, and F⁴ are absent.

In one aspect, each fluorescent luminophore is independently selected from aromatic hydrocarbons and their derivatives, polyphenyl hydrocarbons, hydrocarbons with condensed aromatic nuclei, naphthalene, anthracene, phenanthrene, chrysene, pyrene, triphenylene, perylene, acenapthene, tetracene, pentacene, tetraphene, coronene, fluorene, biphenyl, p-terphenyl, o-diphenylbenzene, m-diphenylbenzene, p-quaterphenyl, benzo[a]tetracene, benzo[k]tetraphene, indeno[1,2,3-cd]fluoranthene, tetrabenzo[de,hi,op,st]pentacene, arylethylene, arylacetylene and their derivatives, diarylethylenes, diarylpolyenes, diaryl-substituted vinylbenzenes, distyrylbenzenes, trivinylbenzenes, arylacetylenes, stilbene and functional substitution products of stilbene.

In another aspect, each fluorescent luminophore is independently selected from substituted or unsubstituted five-, six- or seven-membered heterocyclic compounds, furan, thiophene, pyrrole and their derivatives, aryl-substituted oxazoles, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, aryl-substituted 2-pyrazolines and pyrazoles, benzazoles, 2H-benzotriazole and its substitution products, heterocycles with one, two or three nitrogen atoms, oxygen-containing heterocycles, coumarins and their derivatives, miscellaneous dyes, acridine dyes, xanthene dyes, oxazines, and thiazines.

In yet another aspect, for any of the formulas disclosed herein, each of F¹, F², F³, and F⁴, if present, is independently one of the following:

1. Aromatic Hydrocarbons and Their Derivatives

2. Arylethylene, Arylacetylene and their Derivatives

4. Other Fluorescent Luminophors

wherein each of R¹¹, R²¹, R³¹, R⁴¹, R⁵¹, R⁶¹, R⁷¹ and R⁸¹ is independently a mono-, di-, or tri-substitution, and if present each of R¹¹, R²¹, R³¹, R⁴¹, R⁵¹, R⁶¹, R⁷¹, and R⁸¹ is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, substituted or unsubstituted alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof,

wherein each of Y^a, Y^b, Y^c, Y^d, Y^e, Y^f, Y^g, Y^h, Yⁱ, Y^j, Y^k, Y^l, Y^m, Yⁿ, Y^o, and Y^p is independently C, N, or B,

wherein each of U^a, U^b, and U^c is independently CH₂, CR¹R², C═O, CH₂, SiR¹R², GeH₂, GeR¹R², NH, NR³, PH. PR³, R³P═O, AsR³, R³As═O, O, S, S═O, SO₂, Se, Se═O, SeO₂, BH, BR³, R³Bi═O, BiH, or BiR³, and

wherein each of W, W^a, W^b, and W^c is independently CH, CR¹, SiR¹, GeH, GeR¹, N, P. B, Bi, or Bi═O.

In one aspect, F¹ is covalently bonded to L¹ directly. In one aspect F² is covalently bonded to L² directly. In one aspect, F³ is covalently bonded to L³ directly. In one aspect, F⁴ is covalently bonded to L⁴ directly.

In another aspect, fluorescent luminophore F¹ is covalently bonded to L¹ by a linking atom or linking group. In another aspect, F² is covalently bonded to L² by a linking atom or linking group. In another aspect, F³ is covalently bonded to L³ by a linking atom or linking group. In another aspect, F⁴ is covalently bonded to L⁴ by a linking atom or linking group.

F. Linking Atoms or Linking Groups

In some cases, each linking atom or linking group in the structures disclosed herein is independently one of the atoms or groups depicted below:

wherein x is an integer from 1 to 10, wherein each of R^s1, R^t1, R^u1, and R^v1 is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, or polymeric, or any conjugate or combination thereof. In other cases, a linking atom or linking group in the structures disclosed herein includes other structures or portions thereof not specifically recited herein, and the present disclosure is not intended to be limited to those structures or portions thereof specifically recited.

In one aspect, x is an integer from 1 to 3. In another aspect, x is 1. In yet another aspect, x is 2. In yet another aspect, x is 3. In yet another aspect, x is 4. In yet another aspect, x is 5. In yet another aspect, x is 6. In yet another aspect, x is 7. In yet another aspect, x is 8. In yet another aspect, x is 9. In yet another aspect, x is 10.

In one aspect, the linking atom and linking group recited above can be covalently bonded to any atom of the fluorescent luminophore F¹, F², F³, and F⁴ if valency permits. For example, if F¹is

can be

In one aspect, one or more of F¹. F². F³, and F⁴ is independently selected from Rhodamine, fluorescein, Texas red, Acridine Orange, Alexa Fluor (various), Allophycocyanin, 7-aminoactinomycin D, BOBO-1, BODIPY (various). Calcien, Calcium Crimson, Calcium green, Calcium Orange, 6-carboxyrhodamine 6G, Cascade blue, Cascade yellow, DAPI, DiA, DiD, DiI. DiO, DiR, ELF 97, Eosin, ER Tracker Blue-White, EthD-1, Ethidium bromide. Fluo-3, Fluo4, FM1-43, FM4-64, Fura-2, Fura Red. Hoechst 33258, Hoechst 33342, 7-hydroxy-4-methylcoumarin, Indo-1, JC-1, JC-9, JOE dye, Lissamine rhodamine B, Lucifer Yellow CH, LysoSensor Blue DND-167, LysoSensor Green, LysoSensor Yellow/Blu, Lysotracker Green FM, Magnesium Green, Marina Blue, Mitotracker Green FM, Mitotracker Orange CMTMRos, MitoTracker Red CMXRos, Monobromobimane, NBD amines, NeruoTrace 500/525 green, Nile red, Oregon Green, Pacific Blue. POP-1, Propidium iodide, Rhodamine 110, Rhodamine Red, R-Phycoerythrin, Resorfin, RH414, Rhod-2, Rhodamine Green, Rhodamine 123, ROX dye, Sodium Green, SYTO blue (various), SYTO green (Various), SYTO orange (various), SYTOX blue, SYTOX green, SYTOX orange, Tetramethylrhodamine B, TOT-1, TOT-3, X-rhod-1, YOYO-1, YOYO-3.

In one aspect, a linking atom and linking group recited above is covalently bonded to any atom of a fluorescent luminophore F¹, F², F³, and F⁴ if present and if valency permits. In one example, if F¹ is

G. R Groups

In one aspect, at least one R¹ is present. In another aspect, R^a is absent.

In one aspect, R^a is a mono-substitution. In another aspect, R^a is a di-substitution. In yet another aspect, R^a is a tri-substitution.

In one aspect, R^a is connected to at least Y¹. In another aspect, R^a is connected to at least Y². In yet another aspect, R^a is connected to at least Y³. In one aspect, R^as are independently connected to at least Y¹ and Y². In one aspect, R^as are independently connected to at least Y¹ and Y³. In one aspect, R^as are independently connected to at least Y² and Y³. In one aspect, R^as are independently connected to Y¹, Y², and Y³.

In one aspect, R^a is a di-substitution and the R^a's are linked together. When the R^a's are linked together the resulting structure can be a cyclic structure that includes a portion of the five-membered cyclic structure as described herein. For example, a cyclic structure can be formed when the di-substitution is of Y¹ and Y² and the R^a's are linked together. A cyclic structure can also be formed when the di-substitution is of Y² and Y³ and the R^a's are linked together. A cyclic structure can also be formed when the di-substitution is of Y³ and Y⁴ and the R^a's are linked together.

In one aspect, each R^a, if present, is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof, and wherein two or more of R^a are optionally linked together. In one aspect, at least one R^a is halogen, hydroxyl, substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl; or any conjugate or combination thereof, and wherein two or more of R^a are optionally linked together.

In one aspect, at least one R^b is present. In another aspect, R^b is absent.

In one aspect, R^b is a mono-substitution. In another aspect, R^b is a di-substitution. In yet another aspect, R^b is a tri-substitution.

In one aspect, each R^b, if present, is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof, and wherein two or more of R^b are optionally linked together. In one aspect, at least one R^b is halogen, hydroxyl; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl; or any conjugate or combination thereof, and wherein two or more of R^b are optionally linked together.

In one aspect, at least one R^c is present. In another aspect, R^c is absent.

In one aspect, R^c is a mono-substitution. In another aspect, R^c is a di-substitution. In yet another aspect, R^c is a tri-substitution.

In one aspect, each R^c, if present, is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof, and wherein two or more of R^c are optionally linked together. In one aspect, at least one R^c is halogen, hydroxyl; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl; or any conjugate or combination thereof, and wherein two or more of R^c are optionally linked together.

In one aspect, at least one R^d is present. In another aspect, R^d is absent.

In one aspect, R^d is a mono-substitution. In another aspect, R^d is a di-substitution. In yet another aspect, R^d is a tri-substitution.

In one aspect, each R^d, if present, is independently deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, substituted silyl, polymeric, or any conjugate or combination thereof, and wherein two or more of R^d are optionally linked together.

In one aspect, R¹ and R² are linked to form the cyclic structure:

In one aspect, each of R, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, and R⁸ is independently hydrogen, deuterium, halogen, hydroxyl, thiol, nitro, cyano, nitrile, isonitrile, sulfinyl, mercapto, sulfo, carboxyl, hydrazino; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, silyl, polymeric; or any conjugate or combination thereof.

In another aspect, each of R, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, and R⁸ is independently hydrogen, halogen, hydroxyl, thiol, nitro, cyano; substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, or amino. In another aspect, each of R, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, and R⁸ is independently hydrogen; or substituted or unsubstituted: aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, or alkynyl.

F. X Groups

In one aspect, X is N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, or Bi═O. In one example, X is N or P. In another example, X is P═O, As, As═O, CR¹, CH, SiR¹, SiH. GeR¹, GeH, B, Bi. or Bi═O. In another aspect, X is Z, Z¹, or Z².

In one aspect, X¹ is N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH. GeR¹, GeH, B, Bi, or Bi═O. In one example, X¹ is N or P. In another example, X¹ is P═O. As, As═O. CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, Bi═O. In another aspect, X¹ is Z, Z¹, or Z².

In one aspect, X² is N, P, P═O, As, As═O, CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, or Bi═O. For example, X² is N or P. In another example, X² is P═O, As, As═O. CR¹, CH, SiR¹, SiH, GeR¹, GeH, B, Bi, Bi═O. In another aspect, X² is Z. Z¹, or Z².

G. Y Groups

In one aspect, each of Y¹, Y², Y³, Y⁴, Y⁵, Y⁶, Y⁷ Y⁸, Y⁹, Y¹⁰, Y¹¹, Y¹², Y¹³, Y¹⁴, Y¹⁵ and Y¹⁶ is independently C, N, O, S, S═O, SO₂. Se. Se═O, SeO₂, PR³, R³P═O, AsR³, R³As═O, or BR³.

In another aspect, each of Y¹, Y², Y³, Y⁴, Y⁵, Y⁶, Y⁷ Y⁸, Y⁹, Y¹⁰, Y¹¹, Y¹². Y¹³, Y¹⁴, Y¹⁵ and Y¹⁶ is independently C or N.

H. Exemplary Compounds

Exemplary compounds include Structures 1-102 below. For any of Structures 1-102 below, as applicable:

M is palladium or platinum:

each of U, U¹ and U² is independently CH₂, CR¹R², C═O, CH₂, SiR¹R², GeH₂, GeR¹R², NH, NR³, PH, PR³, R¹P═O, AsR³, R³As═O, O, S, S═O, SO₂, Se, Se═O, SeO₂, BH, BR³, R³Bi═O, BiH or BiR³,

each of R, R¹, R², R³, and R⁴ is independently hydrogen, aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, deuterium, halogen, hydroxyl, thiol, nitro, cyano, amino, a mono- or di-alkylamino, a mono- or diaryl amino, alkoxy, aryloxy, haloalkyl, aralkyl, ester, nitrile, isonitrile, heteroaryl, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, sulfinyl, ureido, phosphoramide, amercapto, sulfo, carboxyl, hydrazino, substituted silyl, or polymerizable, or any conjugate or combination thereof,

and n is an integer from 1 to 100 (e.g., 1-10).

2. Devices

Also disclosed herein are devices including one or more of the compounds disclosed herein.

The compounds disclosed herein are suited for use in a wide variety of devices, including, for example, optical and electro-optical devices, including, for example, photo-absorbing devices such as solar- and photo-sensitive devices, organic light emitting diodes (OLEDs), photo-emitting devices, or devices capable of both photo-absorption and emission and as markers for bio-applications.

Compounds described herein can be used in a light emitting device such as an OLED. FIG. 2 depicts a cross-sectional view of an OLED 100. OLED 100 includes substrate 102, anode 104, hole-transporting material(s) (HTL) 106, light processing material 108, electron-transporting material(s) (ETL) 110, and a metal cathode layer 112. Anode 104 is typically a transparent material, such as indium tin oxide. Light processing material 108 may be an emissive material (EML) including an emitter and a host.

In various aspects, any of the one or more layers depicted in FIG. 1 may include indium tin oxide (ITO), poly(3,4-ethylenedioxythiophene) (PEDOT), polystyrene sulfonate (PSS), N,N′-di-1-naphthyl-N,N-diphenyl-1,1′-biphenyl-4,4′diamine (NPD), 1,1-bis((di-4-tolylamino)phenyl)cyclohexane (TAPC), 2,6-Bis(N-carbazolyl)pyridine (mCpy), 2,8-bis(diphenylphosphoryl)dibenzothiophene (PO15). LiF, Al, or a combination thereof.

Light processing material 108 may include one or more compounds of the present disclosure optionally together with a host material. The host material can be any suitable host material known in the art. The emission color of an OLED is determined by the emission energy (optical energy gap) of the light processing material 108, which can be tuned by tuning the electronic structure of the emitting compounds, the host material, or both. Both the hole-transporting material in the HTL layer 106 and the electron-transporting material(s) in the ETL layer 110 may include any suitable hole-transporter known in the art.

Compounds described herein may exhibit phosphorescence. Phosphorescent OLEDs (i.e., OLEDs with phosphorescent emitters) typically have higher device efficiencies than other OLEDs, such as fluorescent OLEDs. Light emitting devices based on electrophosphorescent emitters are described in more detail in WO2000/070655 to Baldo et al., which is incorporated herein by this reference for its teaching of OLEDs, and in particular phosphorescent OLEDs.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary and not intended to limit the scope of the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ° C. or is at ambient temperature, and pressure is at or near atmospheric.

Various methods for the preparation method of the compounds described herein are recited in the examples. These methods are provided to illustrate various methods of preparation, but this disclosure is not intended to be limited to any of the methods recited herein. Accordingly, one of skill in the art in possession of this disclosure could readily modify a recited method or utilize a different method to prepare one or more of the compounds. The following aspects are only exemplary and are not intended to limit the scope of the disclosure. Temperatures, catalysts, concentrations, reactant compositions, and other process conditions can vary, and one of skill in the art, in possession of this disclosure, could readily select appropriate reactants and conditions for a desired complex.

¹H spectra were recorded at 400 MHz, ¹³C NMR spectra were recorded at 100 MHz on Varian Liquid-State NMR instruments in CDCl₃ or DMSO-d₆ solutions and chemical shifts were referenced to residual protiated solvent. If CDCl₃ was used as solvent, ¹H NMR spectra were recorded with tetramethylsilane (δ=0.00 ppm) as internal reference; ¹³C NMR spectra were recorded with CDCl₃ (δ=77.00 ppm) as internal reference. If DMSO-d₆ was used as solvent. ¹H NMR spectra were recorded with residual H₂O (δ=3.33 ppm) as internal reference; ¹³C NMR spectra were recorded with DMSO-d₆ (δ=39.52 ppm) as internal reference. The following abbreviations (or combinations thereof) were used to explain ¹H NMR multiplicities: s=singlet,d=doublet, t=triplet, q=quartet, p=quintet, m=multiplet, br=broad.

Synthetic Routes

A general synthetic route for the compounds disclosed herein includes:

A synthetic route for the disclosed compounds herein also includes;

Synthesis of 2-bromo-9H-carbazole 1

4′-Bromo-2-nitrobiphenyl (22.40 g, 80.55 mmol) and P(OEt)₃ (150 mL) were added to a three-necked flask equipped with a magnetic stir bar and a condenser under the protection of nitrogen. The mixture was then stirred in an oil bath at a temperature of 150-160° C. for 30 hours, cooled to ambient temperature and the excess P(OEt)₃ was removed by distillation under high vacuum. The residue was recrystallized in toluene to get the desired product 2-bromo-9H-carbazole 8.30 g as a white crystal. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product 2-bromo-9H-carbazole 2.00 g in 52% total yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.17 (t, J=7.6 Hz, 1H), 7.28 (dd, J=8.0, 1.6 Hz, 1H), 7.41 (t, J=7.6 Hz, 1H), 7.49 (d, J=8.4 Hz, 1H), 7.65 (d, J=1.6 Hz, 1H), 8.06 (d, J=8.4 Hz, 1H), 8.11 (d, J=7.6 Hz, 1H), 11.38 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 111.22, 113.50, 118.11, 119.09, 120.36, 121.29, 121.58, 121.79, 121.90, 126.09, 139.89, 140.62.

Synthesis of 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2

2-Bromo-9H-carbazole 1 (3.91 g, 15.89 mmol, 1.0 eq), CuI (0.30 g, 1.59 mmol, 0.1 eq) and K₂CO₃ (4.39 g, 31.78 mmol, 2.0 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then the tube was taken into a glove box. Solvent toluene (60 mL), 1-methyl-1H-imidazole (0.63 mL, 7.95 mmol, 0.5 eq) and 2-bromopyridine (4.55 mL, 47.68 mmol, 3.0 eq) were added. The mixture was bubbled with nitrogen for 10 minutes. The tube was sealed before being taken out of the glove box and the mixture was stirred in an oil bath at a temperature of 120° C. for 6 days, cooled to ambient temperature, filtered and washed with ethyl acetate. The filtrate was concentrated under reduced pressure to remove the solvent and the excess 2-bromopyridine (otherwise it is difficult to separate the desired product and 2-bromopyridine by silica gel column). The residue was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 as an off-white solid 5.11 g in 99% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.33 (t, J=7.6 Hz, 1H), 7.45-7.50 (m, 3H), 7.74 (d, J=8.4 Hz, 1H), 7.78 (d, J=8.0 Hz, 1H), 7.95 (d, J=2.0 Hz, 1H), 8.11 (td, J=8.0, 2.0 Hz, 1H), 8.19 (d, J=8.4 Hz, 1H), 8.24 (d, J=7.6 Hz, 1H), 8.72 (dd, J=4.8, 1.6 Hz, 1H). ¹H NMR (CDCl₃, 400 MHz): δ 7.32 (t, J=7.6 Hz, 2H), 7.41-7.47 (m, 2H), 7.60 (d, J=8.0 Hz, 1H), 7.77 (d, J=8.4 Hz, 1H), 7.91-7.95 (m, 2H), 8.01 (d, J=2.0 Hz, 1H), 8.07 (d, J=8.0 Hz, 1H), 8.72-8.73 (m, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ 111.10, 114.35, 119.01, 119.78, 120.21, 121.26, 121.30, 121.61, 123.16, 123.64, 124.06, 126.58, 138.65, 139.60, 140.29, 149.78, 151.26.

Synthesis of 4-bromo-1-(3-methoxyphenyl)-1H-pyrazole 3

4-Bromo-1H-pyrazole (3674 mg, 25 mmol, 1.0 eq), CuI (95 mg, 0.5 mmol, 0.02 eq) and K₂CO₃ (7256 mg, 52.5 mmol, 2.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then trans-1,2-cyclohexanediamine (570 mg, 5 mmol, 0.2 eq), 1-iodo-3-methoxybenzene (3.57 mL, 30 mmol, 1.2 eq) and solvent dioxane (50 mL) were added in a nitrogen filled glove box. The mixture was bubbled with nitrogen for 5 minutes. The tube was sealed before being taken out of the glove box. The mixture was stirred in an oil bath at a temperature of 100° C. for two days. Then the mixture was cooled to ambient temperature, filtered and washed with ethyl acetate. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (20:1-15:1) as eluent to obtain the desired product 4-bromo-1-(3-methoxyphenyl)-1H-pyrazole 3 as a colorless sticky liquid 4.09 g in 65% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 3.82 (s, 3H), 6.89-6.92 (m, 1H), 7.39-7.41 (m, 3H), 7.86 (s, 1H), 8.81 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 55.45, 94.92, 104.01, 110.35, 112.54, 128.30, 130.51, 140.26, 141.16, 160.15.

Synthesis of 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-1H-pyrazole 4

To a three-necked flask equipped with a magnetic stir bar and a condenser was added biphenyl-4-ylboronic acid (1012 mg, 5.11 mmol, 1.2 eq), Pd₂(dba)₃ (156 mg, 0.17 mmol, 0.04 eq) and tricyclohexylphosphine PCy₃ (115 mg, 0.41 mmol, 0.096 eq). Then the flask was evacuated and backfilled with nitrogen, the evacuation and backfill procedure was repeated twice. Then a solution of 4-bromo-1-(3-methoxyphenyl)-1H-pyrazole 3 (1078 mg, 4.26 mmol, 1.0 eq) in dioxane (25 mL) and a solution of K₃PO₄ (1537 mg, 7.24 mmol, 1.7 eq) in H₂O (10 mL) were added by syringe independently under nitrogen. The mixture was stirred in an oil bath at a temperature of 95-105° C. for 20 hours, cooled to ambient temperature, filtered and washed with ethyl acetate. The organic layer of the filtrate was separated, dried over sodium sulfate, filtered, concentrated and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-1H-pyrazole 4 as a brown solid in quantitative yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 3.85 (s, 3H), 6.90 (dd, J=8.0, 2.4 Hz, 1H), 7.36-7.50 (m, 6H), 7.70-7.73 (m, 4H), 7.82 (d, J=8.4 Hz, 2H), 8.26 (s, 1H), 9.07 (s, 1H).

Synthesis of 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5

A solution of 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-1H-pyrazole 4 (4.26 mmol) in a mixture of acetic acid (20 mL) and hydrogen bromide acid (10 mL, 48%) refluxed (120-130° C.) for 18 hours at an atmosphere of nitrogen. Then the mixture was cooled. After most of the acetic acid was removed under reduced pressure, the residue was neutralized with a solution of K₂CO₃ in water until there was no gas to generate. Then the precipitate was filtered off and washed with water for several times. The collected solid was dried in air to afford the product 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 as a brown solid in quantitative yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 6.59 (dt, J=6.8, 2.0 Hz, 1H), 7.23-7.28 (m, 3H), 7.32 (t, J=7.6 Hz, 1H), 7.43 (t, J=8.0 Hz, 2H), 7.67 (d, J=8.8 Hz, 4H), 7.77 (d, J=8.4 Hz, 2H), 8.19 (s, 1H), 8.94 (s, 1H), 9.76 (bs, 1H).

Synthesis of 2-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1a

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 (2.13 mmol, 1.0 eq), 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 (827 mg, 2.56 mmol, 1.2 eq), CuI (40 mg, 0.21 mmol, 0.1 eq), picolinic acid (52 mg, 0.42 mmol, 0.2 eq) and K₃PO₄ (904 mg, 4.26 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (12 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve solid. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product Ligand ON1a as a brown solid 1143 mg in 97% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 6.96 (dd, J=8.0, 2.0 Hz, 1H), 7.09 (dd, J=8.4, 2.0 Hz, 1H), 7.33 (t, J=8.0 Hz, 2H), 7.42-7.45 (m, 4H), 7.49 (t, J=8.0 Hz, 1H), 7.57 (d, J=1.6 Hz, 1H), 7.62 (s, 1H), 7.67-7.69 (m, 5H), 7.77 (d, J=8.4 Hz, 4H), 8.05 (td, J=7.6, 1.6 Hz, 1H), 8.21 (d, J=6.0 Hz, 1H), 8.22 (s, 1H), 8.27 (d, J=8.8 Hz, 1H), 8.67 (d, J=3.2 Hz, 1H), 9.07 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 102.49, 107.87, 111.12, 112.56, 113.28, 115.55, 119.02, 120.07, 120.19, 121.25, 121.79, 122.11, 123.28, 123.86, 124.79, 125.83, 125.98, 126.40, 127.07, 127.34, 128.90, 130.80, 131.02, 138.27, 138.85, 139.35, 139.49, 139.67, 139.96, 140.89, 149.52, 150.48, 154.84, 158.53.

Synthesis of 2-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Platinum Complex PtON1a

To a dry pressure tube equipped with a magnetic stir bar was added Ligand ON1a (554 mg, 1.0 mmol, 1.0 eq), K₂PtCl₄ (440 mg, 1.05 mmol, 1.05 eq), ⁿBu₄NBr (32 mg, 0.1 mmol, 0.1 eq) and solvent acetic acid (60 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 23 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature and water (120 mL) was added. The precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through flash column chromatography on silica gel using dichloromethane as eluent to obtain the platinum complex PtON1a a yellow solid 530 mg in 71% total yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.01 (d, J=8.4 Hz, 1H), 7.24 (d, J=8.0, 1H), 7.29 (t, J=8.0 Hz, 1H), 7.39-7.45 (m, 2H), 7.49-7.54 (m, 4H), 7.58 (d, J=8.4 Hz, 1H), 7.78 (d, J=8.0 Hz, 2H), 7.82 (d, J=8.8 Hz, 2H), 7.90 (d, J=8.0 Hz, 1H), 8.02 (d, J=8.4 Hz, 2H), 8.11 (d, J=8.0 Hz, 1H), 8.18 (d, J=8.0 Hz, 1H), 8.27 (td, J=8.0, 1.6 Hz, 1H), 8.31 (d, J=8.0 Hz, 1H), 8.72 (s, 1H), 9.39 (d, J=4.8 Hz, 1H), 9.49 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 98.84, 106.06, 110.98, 112.54, 113.29, 114.92, 115.64, 115.76, 116.14, 119.97, 120.60, 122.94, 123.39, 124.54, 124.83, 125.46, 126.21, 126.53, 127.18, 127.52, 127.87, 128.98, 129.93, 137.09, 137.98, 138.90, 139.61, 139.79, 141.83, 146.00, 147.50, 152.29, 152.49, 152.56. FIG. 3 shows emission spectra of PtON1a in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

2. Example 2

Platinum complex PtON1a-tBu can be prepared according to the following scheme:

Synthesis of 2-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole Ligand ON1a-tBu

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 (1.06 mmol, 1.0 eq), 2-bromo-9-(4-tert-butylpyridin-2-yl)-9H-carbazole (482 mg, 1.27 mmol, 1.2 eq), CuI (20 mg, 0.11 mmol, 0.1 eq), picolinic acid (26 mg, 0.21 mmol, 0.2 eq) and K₃PO₄ (452 mg, 2.13 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (6 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve the salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-3:1) as eluent to obtain the desired product as a brown solid 595 mg in 92% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.20 (s, 9H), 7.01 (d, J=8.4 Hz, 1H), 7.13 (d, J=8.8 Hz, 1H), 7.29-7.34 (m, 3H), 7.38-7.45 (m, 4H), 7.50 (t, J=8.0 Hz, 1H), 7.59 (s, 1H), 7.66-7.71 (m, 6H), 7.75-7.78 (m, 3H), 8.20 (d, J=8.0 Hz, 1H), 8.22 (s, 1H), 8.27 (d, J=7.6 Hz, 1H), 8.54 (d, J=4.8 Hz, 1H), 9.09 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 29.95, 34.75, 100.91, 108.60, 111.27, 112.86, 113.03, 115.69, 116.44, 119.24, 119.65, 120.08, 121.13, 121.89, 123.22, 123.87, 124.79, 125.80, 125.85, 126.40, 127.07, 127.34, 128.90, 130.82, 131.14, 138.27, 138.85, 139.45, 139.67, 139.89, 141.01, 149.38, 150.62, 155.66, 157.86, 162.99.

Synthesis of 2-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1a-tBu

To a dry pressure tube equipped with a magnetic stir bar was added Ligand ON1a-tBu (557 mg, 0.91 mmol, 1.0 eq), K₂PtCl₄ (400 mg, 0.95 mmol, 1.05 eq), ⁿBu₄NBr (29 mg, 0.091 mmol, 0.1 eq) and solvent acetic acid (55 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 15 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature and water (110 mL) was added. The precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure and purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to obtain a yellow solid 367 mg. The product (320 mg) was further purified by sublimation to get PtON1a-tBu 85 mg as a yellow solid in 13% total yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.40 (s, 9H), 7.00 (d, J=8.8 Hz, 1H), 7.22 (d, J=8.4 Hz, 1H), 7.27 (t, J=8.0 Hz, 1H), 7.38-7.43 (m, 2H), 7.49-7.57 (m, 5H), 7.77 (d, J=6.8 Hz, 2H), 7.81 (d, J=8.0 Hz, 2H), 7.90 (d, J=8.0 Hz, 1H), 8.02 (d, J=8.0 Hz, 2H), 8.09 (d, J=8.0 Hz, 1H), 8.17 (s, 1H), 8.18 (d, J=8.4 Hz, 1H), 8.74 (s, 1H), 9.26 (d, J=6.4 Hz, 1H), 9.48 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 29.71, 35.53, 98.81, 106.13, 111.26, 112.45, 112.58, 113.37, 114.63, 115.69, 115.79, 118.46, 120.20, 122.98, 123.49, 124.72, 124.85, 125.50, 126.32, 126.60, 127.25, 127.61, 127.95, 129.08, 129.99, 137.09, 138.15, 138.98, 139.69, 142.07, 146.04, 147.51, 152.02, 152.35, 152.61, 163.14. FIG. 4 shows emission spectra of PtON1a-tBu in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K. FIG. 5 shows EL spectra for the devices of ITO/HATCN (10 nm)/NPD (40 nm)/TAPC (10 nm)/26mCPy: 6% PtON1a-tBu/DPPS (10 nm)/BmPyPB (40 nm)/LiF/AL. FIG. 6 shows external quantum efficiency (% photon/electron) vs. current density (mA/cm²) for the devices of ITO/HATCN (10 nm)/NPD (40 nm)/TAPC (10 nm)/26mCPy: 6% PtON1a-tBu/DPPS (10 nm)/BmPyPB (40 nm)/LiF/AL

3. Example 3

Platinum complex PtOO1a can be prepared according to the following scheme:

Synthesis of 2-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine Ligand OO1a

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 (1.06 mmol, 1.0 eq), 2-(3-bromophenoxy)pyridine (318 mg, 1.27 mmol, 1.2 eq), CuI (20 mg, 0.11 mmol, 0.1 eq), picolinic acid (26 mg, 0.21 mmol, 0.2 eq) and K₃PO₄ (452 mg, 2.13 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (6 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve the salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-3:1) as eluent to obtain the desired product as a brown solid 425 mg in 93% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 6.87 (t, J=2.0 Hz, 1H), 6.91-6.94 (m, 2H), 7.00 (dd, J=8.4, 2.0 Hz, 1H), 7.05 (d, J=8.0 Hz, 1H), 7.11-7.14 (m, 1H), 7.35 (t, J=7.6 Hz, 1H), 7.42-7.47 (m, 3H), 7.54 (t, J=7.6 Hz, 1H), 7.65-7.66 (m, 1H), 7.69-7.72 (m, 5H), 7.80-7.86 (m, 3H), 8.16-8.18 (m, 1H), 8.27 (s, 1H), 9.10 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 108.74, 111.70, 111.75, 113.27, 114.48, 116.34, 116.38, 119.36, 123.92, 124.83, 125.84, 126.42, 127.09, 127.36, 128.92, 130.82, 131.16, 138.30, 138.94, 139.69, 140.27, 140.96, 147.46, 155.22, 157.17, 157.34, 162.62.

Synthesis of 2-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine platinum complex PtOO1a

To a dry pressure tube equipped with a magnetic stir bar was added 2-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine Ligand OO1a (452 mg, 0.94 mmol, 1.0 eq), K₂PtCl₄ (415 mg, 0.99 mmol, 1.05 eq), ⁿBu₄NBr (30 mg, 0.094 mmol, 0.1 eq) and solvent acetic acid (56 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 18 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature and water (112 mL) was added. The precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure and purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to obtain PtOO1a as a yellow solid 449 mg in 71% yield. ¹H NMR (DMSO-d, 400 MHz): δ 6.88 (d, J=7.6 Hz, 1H), 6.91 (d, J=8.4 Hz, 1H), 6.96 (dd, J=8.4, 0.8 Hz 1H), 7.08 (t, J=8.0 Hz, 1H), 7.20 (d, J=8.0 Hz, 1H), 7.33 (t, J=7.6 Hz, 1H), 7.40-7.45 (m, 3H), 7.47 (d, J=7.6 Hz, 1H), 7.49 (d, J=8.4 Hz, 1H), 7.68 (d, J=7.6 Hz, 2H), 7.71 (d, J=8.0 Hz, 2H), 7.88 (d, J=8.0 Hz, 2H), 8.15-8.19 (m, 1H), 8.37 (s, 1H), 8.91 (d, J=4.0 Hz, 1H), 9.34 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 102.98, 106.19, 109.99, 111.80, 112.34, 112.99, 115.59, 121.24, 123.21, 124.44, 124.88, 125.19, 126.18, 126.49, 127.11, 127.46, 128.93, 129.80, 136.91, 138.84, 139.58, 141.39, 145.83, 149.78, 152.20, 153.55, 154.54, 158.11. FIG. 7 shows emission spectra of PtOO1a at room temperature in CH₂Cl₂ and at 77K in 2-methyltetrahydrofuran.

4. Example 4

Platinum complex PtON1b can be prepared according to the following scheme:

Synthesis of 3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenol 6

To a three-necked flask equipped with a magnetic stir bar and a condenser was added 9,9-dibutyl-9H-fluoren-2-ylboronic acid (1805 mg, 5.60 mmol, 1.4 eq), Pd2(dba)₃ (14 mg, 70.16 mmol, 0.04 eq) and tricyclohexylphosphine PCy₃ (108 mg, 0.38 mmol, 0.096 eq). Then the flask was evacuated and backfilled with nitrogen, the evacuation and backfill procedure was repeated twice. Then a solution of 4-bromo-1-(3-methoxyphenyl)-1H-pyrazole 3 (1012 mg, 4.00 mmol, 1.0 eq) in dioxane (25 mL) and a solution of K₃PO₄ (1443 mg, 6.80 mmol, 1.7 eq) in H₂O (10 mL) were added by syringe independently under nitrogen. The mixture was stirred at a temperature of 95-105° C. for 27 hours, cooled to ambient temperature, filtered and washed with ethyl acetate. The organic layer of the filtrate was separated, dried over sodium sulfate, filtered, concentrated and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (20:1-15) as eluent to obtain a colorless sticky liquid which was used directly for the next step. A solution of the sticky liquid in a mixture of acetic acid (30 mL) and hydrogen bromide acid (15 mL, 48%) stirred at a temperature of 125-130° C. for 17 hours under nitrogen. Then the mixture was cooled. After most of the acetic acid was removed under reduced pressure, the residue was neutralized with a solution of K₂CO₃ in water until there was no gas to generate. Then the precipitate was filtered off and washed with water for several times. The collected solid was dried in air to afford the product 3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenol 6 as a brown solid in 83% total yield for the two steps. ¹H NMR (DMSO-d₆, 400 MHz): δ 0.19-0.32 (m, 4H), 0.37 (t, J=7.2 Hz, 6H), 0.74-0.84 (m, 4H), 1.78 (t, J=7.2 Hz, 4H), 6.48 (dt, J=6.8, 2.0 Hz, 1H), 7.03-7.10 (m, 5H), 7.18 (dd, J=6.4, 2.0 Hz, 1H), 7.44 (dd, J=8.0, 1.6 Hz, 1H), 7.53-7.58 (m, 3H), 8.01 (s, 1H), 8.75 (s, 1H), 9.55 (bs, 1H).

Synthesis of 2-(3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1b

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenol 6 (262 mg, 0.60 mmol, 1.0 eq), 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 (233 mg, 0.72 mmol, 1.2 eq), CuI (11 mg, 0.06 mmol, 0.1 eq), picolinic acid (15 mg, 0.12 mmol, 0.2 eq) and K₃PO₄ (255 mg, 1.20 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (4 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve the salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-3:1) as eluent to obtain the desired product as a brown solid 240 mg in 58% yield.

Synthesis of 2-(3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Platinum Complex PtON1b

To a dry pressure tube equipped with a magnetic stir bar was added 2-(3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1b (115 mg, 0.165 mmol, 1.0 eq). K₂PtCl₄ (73 mg, 0.173 mmol, 1.05 eq), ⁿBu₄NBr (5 mg, 0.017 mmol, 0.1 eq) and solvent acetic acid (10 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 11 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:1) as eluent to afford the desired product PtON1b as a yellow solid 69 mg in 47% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 0.48-0.58 (m, 4H), 0.62 (t, =7.6 Hz, 6H), 1.00-1.09 (m, 4H), 2.06 (t, J=8.0 Hz 4H), 7.00 (d, J=8.0 Hz, 1H), 7.22 (d, J=8.4 Hz, 1H), 7.28 (t, J=7.6 Hz, 1H), 7.31-7.36 (m, 2H), 7.40 (t, J=8.0 Hz, 1H), 7.43-7.50 (m, 3H), 7.57 (d, J=7.6 Hz, 1H), 7.83 (dd, J=6.0, 2.4 Hz, 1H), 7.86-7.90 (m, 3H), 7.97 (s, 1H), 8.08 (d, J=8.4 Hz, 1H), 8.16 (d, J=7.6 Hz, 1H), 8.24 (td, J=8.4, 1.6 Hz, 1H), 8.29 (d, J=8.4 Hz, 1H), 8.70 (s, 1H), 9.39 (d, J=6.4 Hz, 1H), 9.46 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 13.79, 22.47, 25.82, 54.70, 98.96, 106.05, 111.05, 112.54, 113.22, 114.88, 115.53, 115.75, 116.16, 119.92, 120.00, 120.35, 120.63, 122.91, 122.95, 124.33, 124.55, 124.79, 125.44, 126.93, 127.20, 127.88, 129.70, 137.16, 137.99, 139.79, 139.83, 140.35, 141.89, 146.10, 147.54, 150.13, 151.18, 152.32, 152.57. FIG. 8 shows emission spectra of PtON1b in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

5. Example 5

Platinum complex PtON1aMe can be prepared according to the following scheme:

Synthesis of 4-bromo-1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 7

4-bromo-3,5-dimethyl-1H-pyrazole (8752 mg, 50 mmol, 1.0 eq), CuI (476 mg, 2.5 mmol, 0.02 eq) and K₂CO₃ (14.51 g, 105 mmol, 2.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then trans-1,2-cyclohexanediamine (1142 mg, 10 mmol, 0.2 eq), 1-iodo-3-methoxybenzene (11.91 mL, 100 mmol, 2.0 eq) and solvent dioxane (50 mL) were added in a nitrogen filled glove box. The mixture was bubbled with nitrogen for 5 minutes. The tube was sealed before being taken out of the glove box. The mixture was stirred in an oil bath at a temperature of 100° C. for three days, cooled to ambient temperature, filtered and washed with ethyl acetate. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product 4-bromo-1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 7 as a brown sticky liquid 11.065 g in 79% yield. ¹H NMR (DMSO-d, 400 MHz): δ 2.20 (s, 3H), 2.30 (s, 3H), 3.81 (s, 3H), 6.99-7.02 (m, 1H), 7.05-7.08 (m, 2H), 7.40-7.44 (m, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 11.53, 12.07, 55.45, 95.61, 109.94, 113.60, 116.36, 129.98, 137.51, 140.46, 146.34, 159.71.

Synthesis of 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-3,5-dimethyl-H-pyrazole 8

To a three-necked flask equipped with a magnetic stir bar and a condenser was added biphenyl-4-ylboronic acid (2376 mg, 12.00 mmol, 1.2 eq), Pd2(dba)₃ (366 mg, 0.40 mmol, 0.04 eq) and tricyclohexylphosphine PCy₃ (269 mg, 0.96 mmol, 0.096 eq). Then the flask was evacuated and backfilled with nitrogen, the evacuation and backfill procedure was repeated twice. Then a solution of 4-bromo-1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 7 (2812 mg, 10.00 mmol, 1.0 eq) in dioxane (63 mL) and a solution of K₃PO₄ (3608 mg, 17.00 mmol, 1.7 eq) in H₂O (25 mL) were added by syringe independently under nitrogen. The mixture was stirred in an oil bath at a temperature of 95-105° C. for 19 hours, cooled to ambient temperature, filtered and washed with ethyl acetate. The organic layer of the filtrate was separated, dried over sodium sulfate, filtered, concentrated and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 8 as a yellow solid in 94%. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.28 (s, 3H), 2.34 (s, 3H), 3.83 (s, 3H), 7.00 (dd, J=8.4, 2.0 Hz, 1H), 7.11-7.14 (m, 2H), 7.38 (t, J=7.6 Hz, 1H), 7.42-7.51 (m, 5H), 7.72-7.74 (m, 2H), 7.76 (d, J=7.6 Hz, 2H).

Synthesis of 3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenol 9

A solution of 4-(biphenyl-4-yl)-1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 8 (3.30 g, 9.31 mmol) in a mixture of acetic acid (40 mL) and hydrogen bromide acid (20 mL, 48%) refluxed (120-130° C.) for 18 hours at an atmosphere of nitrogen, then cooled. After most of the acetic acid was removed under reduced pressure, the residue was neutralized with a solution of K₂CO₃ in water until there was no gas to generate. Then the precipitate was filtered off and washed with water for several times. The collected solid was dried in air to afford the product 3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenol 9 as a brown solid in quantitative yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.27 (s, 3H), 2.32 (s, 3H), 6.80-6.82 (m, 1H), 6.94-6.97 (m, 2H), 7.31 (t, J=7.6 Hz, 1H), 7.38 (t, J=7.6 Hz, 1H), 7.45-7.51 (m, 4H), 7.71-7.77 (m, 4H), 9.77 (bs, 1H).

Synthesis of 2-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1aMe

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenol 9 (163 mg, 0.48 mmol, 1.0 eq), 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 (188 mg, 0.58 mmol, 1.2 eq). CuI (9 mg, 0.048 mmol, 0.1 eq), picolinic acid (12 mg, 0.096 mmol, 0.2 eq) and K₃PO₄ (204 mg, 0.96 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (4 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product 2-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1aMe as a colorless solid 182 mg in 65% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.22 (s, 3H), 2.28 (s, 3H), 7.09-7.14 (m, 2H), 7.18 (s, 1H), 7.31-7.49 (m, 9H), 7.52 (t, J=8.0 Hz, 1H), 7.56 (s, 1H), 7.71 (t, J=8.4 Hz, 4H), 7.79 (dd, J=8.0, 3.2 Hz, 2H), 8.08 (t, J=8.0 Hz, 1H), 8.24 (d, J=7.6 Hz, 1H), 8.30 (d, J=8.8 Hz, 1H), 8.68 (d, J=3.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 11.80, 12.61, 102.53, 111.14, 113.42, 113.62, 116.66, 118.74, 119.08, 120.02, 120.11, 120.25, 121.29, 121.87, 122.18, 123.27, 126.04, 126.58, 126.80, 127.40, 128.98, 129.67, 130.54, 132.25, 136.30, 138.15, 139.37, 139.55, 139.81, 139.96, 140.77, 146.43, 149.55, 150.47, 154.74, 158.05.

Synthesis of 2-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Platinum Complex PtON1aMe

To a dry pressure tube equipped with a magnetic stir bar was added 2-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1aMe (170 mg, 0.29 mmol, 1.0 eq). K₂PtCl₄ (128 mg, 0.30 mmol, 1.05 eq). ⁿBu₄NBr (9 mg, 0.029 mmol, 0.1 eq) and solvent acetic acid (17.4 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 15 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using dichloromethane as eluent to obtain the platinum complex PtON1aMe a yellow solid 163 mg in 72% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.44 (s, 3H), 2.76 (s, 3H), 7.00 (d, J=8.0 Hz, 1H), 7.20 (d, J=8.8, 1H), 7.26 (t, J=8.0 Hz, 1H), 7.30-7.34 (m, 1H), 7.38-7.42 (m, 3H), 7.45-7.52 (m, 3H), 7.56 (d, J=8.0 Hz, 2H), 7.75 (d, J=8.0 Hz, 2H), 7.82 (d, J=8.4 Hz, 2H), 7.88 (d, J=8.0 Hz, 1H), 8.10 (d, J=8.0 Hz, 1H), 8.13-8.21 (m, 3H), 9.34 (d, J=4.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 13.23, 13.88, 100.10, 107.42, 111.07, 112.22, 112.64, 115.10, 115.40, 115.62, 115.80, 119.13, 119.94, 122.27, 122.90, 124.50, 124.83, 126.71, 127.01, 127.63, 127.95, 129.01, 130.52, 130.69, 137.86, 138.94, 139.25, 139.64, 140.24, 141.84, 147.65, 147.88, 148.04, 151.55, 151.95, 153.92. FIG. 9 shows emission spectra of PtON1aMe in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

6. Example 6

Platinum complex PtOO1aMe can be prepared according to the following scheme:

Synthesis of 2-(3-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine Ligand OO1aMe

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenol 9 (511 mg, 1.50 mmol, 1.0 eq), 2-(3-bromophenoxy)pyridine (450 mg, 1.80 mmol, 1.2 eq), CuI (29 mg, 0.15 mmol, 0.1 eq), picolinic acid (37 mg, 0.30 mmol, 0.2 eq) and K₃PO₄ (637 mg, 3.00 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (9 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve the salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product as a brown solid 521 mg in 68% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.25 (s, 3H), 2.31 (s, 3H), 6.88 (t, J=2.0 Hz, 1H), 6.94 (dd, J=8.4, 2.0 Hz, 2H), 7.05 (d, J=8.0 Hz, 1H), 7.09-7.14 (m, 2H), 7.22 (t, J=2.0 Hz, 1H), 7.34-7.38 (m, 2H), 7.43-7.49 (m, 5H), 7.54 (t, J=8.0 Hz, 1H), 7.70 (d, J=7.2 Hz, 2H), 7.74 (d, J=8.0 Hz, 2H), 7.82-7.87 (m, 1H), 8.14-8.16 (m, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 11.81, 12.62, 111.78, 111.96, 114.35, 114.78, 116.52, 117.30, 119.30, 119.37, 120.07, 126.58, 126.82, 127.40, 128.97, 129.68, 130.60, 130.86, 132.25, 136.33, 138.17, 139.81, 140.29, 140.85, 146.48, 147.45, 155.22, 156.83, 157.11, 162.61.

Synthesis of 2-(3-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine platinum complex PtOO1aMe

To a dry pressure tube equipped with a magnetic stir bar was added 2-(3-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine Ligand OO1aMe (245 mg, 0.48 mmol, 1.0 eq), K₂PtCl₄ (211 mg, 0.504 mmol, 1.05 eq), ⁿBu₄NBr (15 mg, 0.048 mmol, 0.1 eq) and solvent acetic acid (29 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 24 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature and water (58 mL) was added. The precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure and purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to obtain PtOO1aMe as a yellow solid 167 mg in 50% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.24 (s, 3H), 2.74 (s, 3H), 6.90-6.96 (m, 3H), 7.08 (t, J=8.0 Hz, 1H), 7.22 (t, J=8.0 Hz, 1H), 7.32-7.42 (m, 3H), 7.49-7.53 (m, 4H), 7.57 (d, J=8.4 Hz, 1H), 7.75 (d, J=7.6 Hz, 2H), 7.81 (d, J=8.0 Hz, 2H), 8.15-8.20 (m, 1H), 8.96 (dd, J=6.0, 1.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 13.09, 13.40, 105.33, 107.76, 110.10, 111.91, 112.19, 112.51, 115.74, 120.26, 122.21, 124.25, 124.93, 126.70, 127.01, 127.63, 129.02, 130.46, 130.66, 138.65, 139.24, 139.62, 142.21, 147.37, 148.09, 151.91, 151.97, 152.98, 155.41, 159.42. FIG. 10 shows emission spectra of PtOO1aMe in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

7. Example 7

Platinum complex Pt1aO1Me can be prepared according to the following scheme:

Synthesis of 1-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenyl)-3,5-dimethyl-1H-pyrazole Ligand 1aO1Me

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 (1.50 mmol, 469 mg, 1.0 eq), 1-(3-iodophenyl)-3,5-dimethyl-1H-pyrazole (581 mg, 1.95 mmol, 1.3 eq), CuI (29 mg, 0.15 mmol, 0.1 eq), picolinic acid (37 mg, 0.30 mmol, 0.2 eq) and K₃PO₄ (637 mg, 3.00 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (9 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3 days and then cooled to ambient temperature. Water was added to dissolve the salt. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product as a brown solid 569 mg in 79% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.13 (s, 3H), 2.29 (s, 3H), 6.04 (s, 1H), 7.01 (dd, J=8.4, 2.0 Hz, 1H), 7.01-7.70 (m, 1H), 7.19 (t, J=1.6 Hz, 1H), 7.29-7.32 (m, 1H), 7.35 (d, J=7.2 Hz, 1H), 7.44 (t, J=7.6 Hz, 2H), 7.51 (t, J=8.0 Hz, 1H), 7.54 (t, =7.6 Hz, 1H), 7.67-7.70 (m, 5H), 7.72-7.75 (m, 1H), 7.79 (d, J=8.4 Hz, 2H), 8.26 (s, 1H), 9.10 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.30, 13.26, 107.61, 108.85, 113.39, 113.99, 116.49, 116.87, 118.90, 123.94, 124.84, 125.84, 126.43, 127.09, 127.36, 128.92, 130.60, 130.81, 131.24, 138.31, 138.96, 139.34, 139.69, 141.02, 141.11, 148.19, 156.86, 157.20.

Synthesis of 1-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenyl)-3,5-dimethyl-1H-pyrazole Platinum Complex Pt1aO1Me

To a dry pressure tube equipped with a magnetic stir bar was added 1-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenyl)-3,5-dimethyl-H-pyrazole Ligand 1aO1Me (260 mg, 0.572 mmol, 1.0 eq), K₂PtCl₄ (252 mg, 0.601 mmol, 1.05 eq), ⁿBu₄NBr (18 mg, 0.057 mmol, 0.1 eq) and solvent acetic acid (34 mL). The mixture was bubbled with nitrogen for 20 minutes in a nitrogen filled glove box. The tube was sealed before being taken out of the glove box. The mixture was stirred at room temperature for 20 hours and followed at 105-115° C. for 3 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to obtain a yellow solid 138 mg in 36% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.78 (s, 3H), 2.80 (s, 3H), 6.50 (s, 1H), 6.98 (t, J=7.6 Hz, 2H), 7.22 (t, J=7.6 Hz, 1H), 7.27 (t, J=8.0 Hz, 1H), 7.32 (d, J=7.6 Hz, 1H), 7.39 (t, J=7.2 Hz, 1H), 7.50 (t, J=7.6 Hz, 2H), 7.54 (d, J=7.6 Hz, 1H), 7.74-7.76 (m, 2H), 7.80 (d, J=8.4 Hz, 2H), 7.94 (d, J=8.4 Hz, 2H), 8.61 (s, 1H), 9.43 (s, 1H). FIG. 11 shows emission spectra of Pt1aO1Me in CH2Cl2 at room temperature and in 2-methyltetrahydrofuran at 77K.

8. Example 8

Platinum complex PdON1a can be prepared according to the following scheme:

Synthesis of 2-(3-(4-(biphenyl-4-yl)-H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Palladium Complex PdON1a

Ligand ON1a (222 mg, 0.4 mmol, 1.0 eq), Pd(OAc)₂ (94 mg, 1.05 mmol, 1.05 eq). ⁿBu₄NBr (13 mg, 0.1 mmol, 0.1 eq) were added to a flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent acetic acid (24 mL) was added under nitrogen. The mixture refluxed for 1 day, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using dichloromethane/hexane (2:1) as eluent to obtain the product PdON1a as a white solid 215 mg in 82% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.07 (d, J=8.4 Hz, 1H), 7.25 (d, J=8.4, 1H), 7.34 (t, J=8.0 Hz, 1H), 7.39-7.44 (m, 2H), 7.48-7.56 (m, 4H), 7.58 (d, J=8.0 Hz, 1H), 7.78 (d, J=8.0 Hz, 2H), 7.82 (d, J=8.0 Hz, 2H), 7.97 (d, J=8.4 Hz, 1H), 8.01 (d, J=8.4 Hz, 2H), 8.10 (d, J=8.0 Hz, 1H), 8.19 (d, J=8.4 Hz, 1H), 8.22-8.26 (m, 2H), 8.73 (s, 1H), 9.21 (d, J=5.2 Hz, 1H), 9.49 (s, 1H). FIG. 12 shows emission spectra of PdON1a in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

9. Example 9

Platinum complex PdON1b can be prepared according to the following scheme:

Synthesis of 2-(3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Palladium Complex PdON1b

2-(3-(4-(9,9-dibutyl-9H-fluoren-2-yl)-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1b (115 mg, 0.165 mmol, 1.0 eq), Pd(OAc)₂ (39 mg, 0.173 mmol, 1.05 eq) and ⁿBu₄NBr (5 mg, 0.017 mmol, 0.1 eq) were added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent acetic acid (10 mL) was added under nitrogen and the mixture refluxed for 1.5 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to afford the desired product PdON1b as a white solid 123 mg in 95% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 0.52-0.60 (m, 4H), 0.64 (t, J=7.2 Hz, 6H), 1.04-1.10 (m, 4H), 2.08 (t, J=8.0 Hz, 4H), 7.06 (d, J=8.0 Hz, 1H), 7.24 (dd, J=8.0, 1.2 Hz, 1H), 7.32-7.38 (m, 3H), 7.41 (t, J=7.6 Hz, 1H), 7.46-7.56 (m, 3H), 7.58 (d, J=8.0 Hz, 1H), 7.84-7.92 (m, 3H), 7.96 (d, J=8.0 Hz, 1H), 7.98 (s, 1H), 8.08 (d, J=8.4 Hz, 1H), 8.18 (d, J=7.2 Hz, 1H), 8.21-8.25 (m, 2H), 8.72 (s, 1H), 9.21 (d, J=5.2 Hz, 1H), 9.47 (s, 1H). FIG. 13 shows emission spectra of PdON1b in CH2Cl2 at room temperature and in 2-methyltetrahydrofuran at 77K.

10. Example 10

Palladium complex PdOO1aMe can be prepared according to the following scheme:

Synthesis of 2-(3-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine palladium complex PdOO1aMe

2-(3-(3-(4-(biphenyl-4-yl)-3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)phenoxy)pyridine Ligand OO1aMe (245 mg, 0.48 mmol, 1.0 eq), Pd(OAc)₂ (113 mg, 0.504 mmol, 1.05 eq) and ⁿBu₄NBr (15 mg, 0.048 mmol, 0.1 eq) were added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent acetic acid (29 mL) was added under nitrogen and the mixture refluxed for 2 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to afford the desired product PdOO1aMe as a white solid 278 mg in 94% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.16 (s, 3H), 2.70 (s, 3H), 6.93 (dd, J=8.4, 1.6 Hz, 1H), 6.98-7.00 (m, 2H), 7.15 (t, J=8.0 Hz, 1H), 7.28 (t, J=8.0 Hz, 1H), 7.36-7.42 (m, 3H), 7.49-7.55 (m, 5H), 7.75 (d, J=8.4 Hz, 2H), 7.81 (d, J=8.4 Hz, 2H), 8.13-8.18 (m, 1H), 8.80 (dd, J=5.6, 1.6 Hz, 1H). FIG. 14 shows emission spectrum of PdOO1aMe at 77K.

11. Example 11

Palladium complex Pd1aO1Me can be prepared according to the following scheme:

Synthesis of 1-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenyl)-3,5-dimethyl-1H-pyrazole Palladium Complex Pd1aO1Me

1-(3-(3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenoxy)phenyl)-3,5-dimethyl-1H-pyrazole Ligand ON1b (260 mg, 0.572 mmol, 1.0 eq), Pd(OAc)₂ (135 mg, 0.601 mmol, 1.05 eq) and ⁿBu₄NBr (18 mg, 0.057 mmol, 0.1 eq) were added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent acetic acid (34 mL) was added under nitrogen and the mixture refluxed for 44 hours, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:2) as eluent to afford the desired product Pd1aO1Me as a white solid 123 mg in 37% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.71 (s, 3H), 2.74 (s, 3H), 6.41 (s, 1H), 7.03 (t, J=7.6 Hz, 2H), 7.27 (t, J=8.0 Hz, 1H), 7.31 (t, J=8.0 Hz, 2H), 7.40 (t, J=7.6 Hz, 1H), 7.51 (t, J=7.6 Hz, 2H), 7.56 (d, J=7.2 Hz, 1H), 7.76 (d, J=7.6 Hz, 2H), 7.80 (d, J=8.0 Hz, 2H), 7.94 (d, J=8.4 Hz, 2H), 8.52 (s, 1H), 9.45 (s, 1H). FIG. 15 shows emission spectra of Pd1aO1Me in CH₂Cl₂ at room temperature and in 2-methyltetrahydrofuran at 77K.

12. Example 12

Palladium complex Pd1aO1a can be prepared according to the following scheme:

Synthesis of 4-(biphenyl-4-yl)-1H-pyrazole 10

4-Bromo-1-trityl-1H-pyrazole (970 mg, 3.35 mmol, 1.0 eq), biphenyl-4-ylboronic acid (796 mg, 4.02 mmol, 1.2 eq), Pd2(dba)₃ (123 mg, 0.134 mmol, 0.04 eq). PCy₃ (90 mg, 0.322 mmol, 0.096 eq) and K₃PO₄ (1210 mg, 5.70 mmol, 1.7 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then the tube was evacuated and backfilled with nitrogen, this evacuation and backfill procedure was repeated twice. Solvent dioxane (21 mL) and H₂O (9 mL) were added under nitrogen. The mixture was stirred in an oil bath at a temperature of 95-105° C. for 24 hours. Then the mixture was cooled to ambient temperature, the precipitate was filtered off and washed with ethyl acetate, dried in air to obtain a brown solid 1053 mg which was used directly for the next step. A mixture of the brown solid (1053 mg) in MeOH (32 mL)/H₂O (27 mL)/HCl (5 mL) was stirred at 40-45° C. for 4 hours, cooled. The organic solvent was removed under reduced pressure. The precipitate was filtered off and washed with water for twice, dried in air. The collected solid was purified through flash column chromatography on silica gel using hexane/ethyl acetate (3:1) first, then dichloromethane/methanol (10:1) as eluent to afford the desired product 4-(biphenyl-4-yl)-1H-pyrazole 10 as a brown solid 430 mg in 58% total yield for the two steps. ¹H NMR (DMSO-d₆. 400 MHz): δ 7.36 (t, J=7.6 Hz, 1H), 7.47 (t, J=8.0 Hz, 2H), 7.65-7.72 (m, 6H), 7.98 (bs, 1H), 8.25 (bs, 1H), 12.97 (bs, 1H).

Synthesis of 4-(biphenyl-4-yl)-1-(3-bromophenyl)-1H-pyrazole 11

To a dry pressure vessel equipped with a magnetic stir bar was added 4-(biphenyl-4-yl)-1H-pyrazole 10 (430 mg, 1.95 mmol, 1.0 eq), L-prolin (90 mg, 0.78 mmol, 0.4 eq), CuI (76 mg, 0.40 mmol, 0.2 eq) and K₂CO₃ (539 mg, 3.90 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (20 mL) and 1,3-dibromobenzene (1.42 mL, 11.70 mmol, 6.0 eq) were added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 6 days and then cooled to ambient temperature. Water was added to dissolve solid. The mixture was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1) as eluent to obtain the desired product

4-(biphenyl-4-yl)-1-(3-bromophenyl)-1H-pyrazole 11 as a brown solid 278 mg in 38% yield. ¹H NMR (DMSO-d₆, 500 MHz): δ 7.37 (t, J=7.0 Hz, 1H), 7.46-7.54 (m, 4H), 7.73 (t, J=7.5 Hz, 4H), 7.83 (d, J=9.0 Hz, 2H), 7.95 (d, J=8.0 Hz, 1H), 8.15 (s, 1H), 8.32 (s, 1H), 9.16 (s, 1H).

96 Synthesis of 1,1′-(3,3′-oxybis(3,1-phenylene))bis(4-(biphenyl-4-yl)-1H-pyrazole) Ligand 1aO1a

To a dry pressure vessel equipped with a magnetic stir bar was added 3-(4-(biphenyl-4-yl)-1H-pyrazol-1-yl)phenol 5 (210 mg, 0.67 mmol, 1.0 eq), 4-(biphenyl-4-yl)-1-(3-bromophenyl)-1H-pyrazole 11 (278 mg, 0.74 mmol, 1.1 eq), CuI (13 mg, 0.067 mmol, 0.1 eq), picolinic acid (16 mg, 0.134 mmol, 0.2 eq) and K₃PO₄ (185 mg, 1.34 mmol, 2.0 eq). The tube was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent DMSO (10 mL) was added under nitrogen. The mixture was stirred at a temperature of 90-100° C. for 3.5 days and then cooled to ambient temperature. Water was added. The precipitate was filtered off. The filtrate was extracted with ethyl acetate three times. The combined organic layer was washed with water three times and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure. The residue and the collected solid were purified through column chromatography on silica gel using hexane/ethyl acetate (4:1) and then dichloromethane/methane (10:1) as eluent to obtain the desired product 1,1′-(3,3′-oxybis(3,1-phenylene))bis(4-(biphenyl-4-yl)-1H-pyrazole) Ligand 1aO1a as a brown solid 309 mg in 76% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.06 (dd, J=8.0, 2.0 Hz, 2H), 7.36 (t, =7.6 Hz, 2H), 7.47 (t, J=8.0 Hz, 4H), 7.59 (t, J=8.0 Hz, 2H), 7.69-7.73 (m, 10H), 7.76 (dd, J=8.0, 2.0 Hz, 2H), 7.82 (d, J=8.4 Hz, 4H), 8.28 (s, 2H), 9.13 (s, 2H).

Synthesis of 1,1′-(3,3′-oxybis(3, I-phenylene))bis(4-(biphenyl-4-yl)-1H-pyrazole) Palladium Complex Pd1aO1a

1,1′-(3,3′-oxybis(3,1-phenylene))bis(4-(biphenyl-4-yl)-H-pyrazole) Ligand 1aO1a (96 mg, 0.158 mmol, 1.0 eq), Pd(OAc)₂ (37 mg, 0.166 mmol, 1.05 eq) and ⁿBu₄NBr (5 mg, 0.016 mmol, 0.1 eq) were added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. This evacuation and backfill procedure was repeated twice. Then solvent acetic acid (10 mL) was added under nitrogen and the mixture refluxed for 2 days, cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through flash column chromatography on silica gel using hexane/dichloromethane (1:3) as eluent to afford the desired product palladium complex Pd1aO1a as a white solid 63.7 mg in 57% yield. δ 7.06 (d, J=7.6 Hz, 2H), 7.32 (t, J=8.0 Hz, 2H), 7.39-7.43 (m, 2H), 7.50-7.56 (m, 6H), 7.79 (d, J=7.6 Hz, 4H), 7.85 (d, J=8.4 Hz, 4H), 8.01 (d, J=8.4 Hz, 4H), 9.05 (s, 2H), 9.45 (s, 2H).

16. Example 16

Platinum complex PtON7a-dtb can be prepared according to the following scheme:

Synthesis of 4-(biphenyl-4-yl)-1H-imidazole 12

A mixture of (8254 mg, 30 mmol, 1.0 eq) and (9458 mg, 7.3 mL, 210 mmol, 7.0 eq) was stirred in an oil bath at 165-175° C. for 8 hours under nitrogen, cooled and then recrystallized in ethyl acetate. Filtered, washed with a little ethyl acetate. The collected solid was dried in air to obtain the desired product 6.23 g as a grey solid.

Synthesis of intermediate 4-(biphenyl-4-yl)-1-(3-bromo-5-tert-butylphenyl)-1H-imidazole 13

4-(Biphenyl-4-yl)-1H-imidazole 12 (3773 mg, 17.13 mmol, 1.0 eq), CuI (326 mg, 1.71 mmol, 0.1 eq), L-proline (394 mg, 3.42 mmol, 0.2 eq), 1,3-dibromo-5-(1,1-dimethylethyl)-benzene (8.00 g, 27.40 mmol, 1.6 eq) and K₂CO₃ (4735 mg, 34.26 mmol, 2.0 eq) were added to a dry pressure tube equipped with a magnetic stir bar. The vissel was then evacuated and backfilled with nitrogen, this evacuation and backfill procedure was repeated for a total of three times. Then DMSO (35 mL) were added in a nitrogen filled glove box. The mixture was bubbled with nitrogen for 5 minutes. The tube was sealed before being taken out of the glove box. The mixture was stirred in an oil bath at a temperature of 105-115° C. for 3 days. Then the mixture was cooled to ambient temperature, filtered and washed with a plenty of ethyl acetate. The filtrate was washed with water three times, dried over sodium sulfate, filtered, concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product 13 as a brown-red solid 2.023 g in 26% total yield for the two steps. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.37 (s, 9H), 7.38 (t, J=7.2 Hz, 1H), 7.49 (t, J=8.0 Hz, 2H), 7.55 (d, J=1.6 Hz, 1H), 7.32-7.75 (m, 5H), 7.88 (d, J=1.2 Hz, 1H), 7.98 (d, J=8.4 Hz, 2H), 8.49 (s, 2H).

Synthesis of 2-(3-(4-(biphenyl-4-yl)-1H-imidazol-1-yl)-5-tert-butylphenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole 15

A mixture of 4-(biphenyl-4-yl)-1H-imidazole 12 (2.00 g, 4.64 mmol, 1.19 eq), 9-(4-tert-butylpyridin-2-yl)-9H-carbazol-2-ol 14 (1.23 g, 3.90 mmol, 1.0 eq), CuI (74 mg, 0.39 mmol, 0.1 eq), picolinic acid (96 mg, 0.78 mmol, 0.20 eq) and K₃PO₄ (1.66 g, 7.80 mmol, 2.0 eq) in DMSO (25 mL) was stirred at a temperature of 95-105° C. for three days under a nitrogen atmosphere, then cooled to ambient temperature. The solid was filtered off and washed with plenty of ethyl acetate. The filtrate was washed with water for three time and then dried over sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (110:1-5:1-3:1) as eluent to obtain the desired product as a brown solid 2.28 g in 88% yield. ¹H NMR (DMSO-d₆. 400 MHz): δ 1.25 (s, 9H), 1.33 (s, 9H), 7.12 (s, 1H), 7.16 (dd, J=8.8, 2.0 Hz, 1H), 7.32-7.50 (m, 8H), 7.55 (s, 1H), 7.62 (s, 1H), 7.71-7.75 (m, 4H), 7.78 (d, J=8.4 Hz, 1H), 7.96 (d, J=8.4 Hz, 2H), 8.23 (d, J=7.6 Hz, 1H), 8.30 (d, J=8.4 Hz, 1H), 8.44 (d, J=4.0 Hz, 2H), 8.57 (d, J=5.2 Hz, 1H).

Synthesis of 1-(3-tert-butyl-5-(9-(4-tert-butylpyridin-2-yl)-9H-carbazol-2-yloxy)phenyl)-3-methyl-4-(biphenyl-4-yl)-1H-imidazol-3-ium hexafluorophosphate (V) Ligand ON7a-dtb

A solution of CH₃I (0.42 mL, 6.75 mmol, 2.0 eq) and 2-(3-(4-(biphenyl-4-yl)-1H-imidazol-1-yl)-5-tert-butylphenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole 15 (2.25 g, 3.37 mmol, 1.0 eq) in toluene (50 mL) was stirred in a sealed vessel at 100-110° C. for 66 hours, cooled, the precipitate was filtered off and washed with Et2O. Then the collected solid dried in air to obtain brown solid 2.52 g which was used directly for the next step. The brown solid (2.50 g, 3.09 mmol, 1.0 eq) was added to a mixture of MeOH/H₂O/Acetone (80 mL/15 mL/15 mL). The mixture was stirred for 30 min until the solid was entirely dissolved. Then NH₄PF₆ (0.76 g, 4.64 mmol, 1.5 eq) was added to the solution. The mixture was stirred at room temperature for 2 days, then removed most of the organic solvent. More deionized water was added. The precipitate was collected through filtration, washed with water three times. Then the solid was dried in air to give the desired product Ligand ON7a-dtb as a grey powder 2.468 g in 90% total yield for the two steps. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.30 (s, 9H), 1.35 (s, 9H), 3.96 (s, 3H), 7.16 (dd, J=8.4, 2.0 Hz, 1H), 7.36-7.55 (m, 9H), 7.65 (s, 1H), 7.68 (s, 1H), 7.77-7.81 (m, 5H), 7.92 (d, J=8.0 Hz, 2H), 8.26 (d, J=8.0 Hz, 1H), 8.33 (d, J=8.0 Hz, 1H), 8.59 (d, J=5.6 Hz, 1H), 8.64 (s, 1H), 9.90 (s, 1H).

Synthesis of platinum(II) [6-(1,3-dihydro-3-methyl-4-(biphenyl-4-yl)-2H-imidazol-2-ylidene-κC²)-4-tert-butyl-1,2-phenylene-κC¹]oxy[9-(4-tert-butyltpyridin-2-yl-κN)-9H-carbazole-1,2-diyl-κC¹] (PtON7a-dtb)

A mixture of 1-(3-tert-butyl-5-(9-(4-tert-butylpyridin-2-yl)-9H-carbazol-2-yloxy)phenyl)-3-methyl-4-(biphenyl-4-yl)-1H-imidazol-3-ium hexafluorophosphate(V) Ligand ON7a-dtb (2.04 g, 2.07 mmol, 1.0 eq), Pt(COD)Cl₂ (1.12 g, 2.99 mmol, 1.2 eq; COD=cyclooctadiene) and NaOAc (0.67 g, 8.16 mmol, 3.3 eq) in CH₃CN (109 mL) was stirred in a pressure vessel at a temperature of 105-115° C. for 3 days under a nitrogen atmosphere, cooled to ambient temperature. The reaction was quenched with water, then extracted with dichloromethane three times. Dried over sodium sulfate. Filtered, the filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/dichloromethane (1:1) as eluent to obtain the desired product platinum complex PtON7a-dtb as a yellow solid 1.46 g in 68% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.36 (s, 9H), 1.39 (s, 9H), 3.94 (s, 3H), 6.90 (d, J=1.2 Hz, 1H), 7.23 (d, J=8.4 Hz, 1H), 7.33 (dd, J=6.0, 2.0 Hz, 1H), 7.36-7.54 (m, 6H), 7.79 (d, J=7.6 Hz, 2H), 7.84-7.90 (m, 5H), 8.08 (d, J=8.4 Hz, 1H), 8.09 (d, J=2.0 Hz, 1H), 8.14 (d, J=7.6 Hz, 1H), 8.48 (s, 1H), 9.56 (d, J=6.0 Hz, 1H).

Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. It is to be understood that the forms shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described herein without departing from the spirit and scope as described in the following claims.

Claims

1. A compound of Formula II:

2. The compound of claim 1, wherein the compound has the structure of Formula IV or Formula VI:

3. The compound of claim 1, wherein the compound has the structure of Formula VIII:

4. The compound of claim 1, wherein the compound has the structure of symmetrical Formula A-24 or the structure of asymmetrical formula A-25:

5. The compound of claim 1, wherein the compound has a neutral charge.

6. The compound of claim 1, wherein each of F1, F2, F3, and F4, if present, is independently selected from the following structures: 1. Aromatic Hydrocarbons and Their Derivatives

7. A compound represented by one of the structures in Structures 1-102;

8. A light-emitting device comprising a compound of claim 1.

9. The light-emitting device of claim 8, wherein the compound demonstrates 100% internal quantum efficiency in the device settings.

10. The light emitting device of claim 8, wherein the device is an organic light emitting diode.

11. The compound of claim 1, wherein A represents O; L3 represents a substituted or unsubstituted phenyl ring; andL4 represents substituted or unsubstituted pyrazole or imidazole.