Heteronuclear bimetallic Pd-Pt dimer, preparation method and application thereof, and organic light-emitting diode

Abstract

The present invention provides a heteronuclear bimetallic Pd-Pt dimer, a preparation method and application thereof, and an organic light-emitting diode, and relates to the technical field of optoelectronic materials. The heteronuclear bimetallic Pd-Pt dimer provided by the present invention shortens the metal-metal distance due to the connecting effect of the bridging ligand, and the luminescence of the heteronuclear bimetallic Pd-Pt dimer is red-shifted. The participation of heavy metal atoms Pd and Pt allows strong spin-orbit coupling to allow effective intersystem crossing between singlet and triplet states, which leads to a high quantum yield of triplet emission. And because the presence of strong field rigid ligands helps to suppress non-radiative decay pathways, high-efficiency luminescence is generated, and the thermodynamic stability is strong. The heteronuclear bimetallic Pd-Pt dimer provided by the present invention is thermodynamically stable, has a high red light quantum yield, high luminescence efficiency, and a long luminescence lifetime, and has good potential application value in organic light-emitting diodes as a phosphorescent luminescent material.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and in particular to a heteronuclear bimetallic Pd-Pt dimer, a preparation method and application thereof, and an organic light-emitting diode. Background Art

[0002] Organic light-emitting diodes (OLEDs) containing phosphorescent materials coordinated with heavy metals can enhance intersystem crossing (ISC) of electrons from singlet to triplet states, utilizing both singlet and triplet excitons simultaneously, theoretically enabling a device internal quantum efficiency of 100%. In practical applications, compared to liquid crystal displays (LCDs), OLEDs do not require a backlight system and can be tuned to emit no light when displaying black, thus achieving infinite contrast. OLEDs also offer advantages such as low power consumption, a wide color gamut, and a wide viewing angle.

[0003] In recent years, phosphorescent materials are mainly dominated by mononuclear Pd materials, mononuclear Pt materials, binuclear Pd-Pd materials, and binuclear Pt-Pt materials, but the red light quantum yield of the above phosphorescent materials is low and the thermodynamic stability is poor. Summary of the Invention

[0004] In view of this, the present invention aims to provide a heteronuclear bimetallic Pd-Pt dimer, a preparation method and application thereof, and an organic light-emitting diode. The heteronuclear bimetallic Pd-Pt dimer provided by the present invention has strong thermodynamic stability, high red light quantum yield, high luminescence efficiency, and long luminescence lifetime.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a heteronuclear bimetallic Pd-Pt dimer having a structure shown in Formula I, Formula II or Formula III:

[0007]

[0008] In the formula I, formula II and formula III, Include any of the following structures:

[0009]

[0010] include

[0011] Include any of the following structures:

[0012]

[0013] wherein R1, R2, R3, R4 and R5 independently include hydrogen, fluorine, methyl, tert-butyl or phenyl; R6, R7, R8, R9 and R 10 independently include hydrogen, methyl, tert-butyl or phenyl; X is CH or N.

[0014] Preferably, the heteronuclear bimetallic Pd-Pt dimer has a structure shown in any one of Formula I-1 to Formula I-2, Formula II-1 to Formula II-8, and Formula III-1 to Formula III-8:

[0015]

[0016]

[0017] The present invention provides a method for preparing the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution, comprising the following steps:

[0018] mixing a bispalladium carboxylic acid dimer, a bisplatinum chloride bridge dimer, a dinitrogen ligand, a polar organic solvent and an alkaline reagent, and performing a replacement reaction to obtain the heteronuclear bimetallic Pd-Pt dimer;

[0019] The double platinum chloride bridge dimer has a structure shown in any one of the following:

[0020]

[0021] The structural formula of the bispalladium carboxylic acid dimer is

[0022] The dinitrogen ligand includes any one of the following structures:

[0023]

[0024] Preferably, the bispalladium carboxylate dimer has a structure shown in any one of Formula IX to Formula XIII:

[0025]

[0026] Preferably, the double platinum chloride bridge dimer has a structure shown in any one of Formula XIV to Formula XVIII:

[0027]

[0028] Preferably, the molar ratio of the bispalladium carboxylic acid dimer to the bisplatinum chloride bridge dimer is 1:1.

[0029] Preferably, the polar organic solvent includes N,N-dimethylformamide or 1,2-dichloroethane.

[0030] Preferably, the temperature of the replacement reaction is 50-120° C., and the time is 12-30 h; the replacement reaction is carried out in a light-proof and protective atmosphere.

[0031] The present invention provides the use of the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution or the heteronuclear bimetallic Pd-Pt dimer prepared by the preparation method described in the above technical solution in organic light-emitting diodes, catalysis and pharmaceuticals.

[0032] The present invention also provides an organic light-emitting diode, wherein the emission layer material is the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution or the heteronuclear bimetallic Pd-Pt dimer prepared by the preparation method described in the above technical solution.

[0033] The heteronuclear bimetallic Pd-Pt dimer provided by the present invention shortens the metal-metal distance due to the connection effect of the bridging ligand (such as N, N'-dibenzamide, etc.), and the complex (heteronuclear bimetallic Pd-Pt dimer) emits red-shifted light. The participation of heavy metal atoms (Pd and Pt) allows strong spin-orbit coupling to allow effective intersystem crossing (ISC) between singlet and triplet states, which results in a high quantum yield of triplet emission. And due to the presence of strong field rigid ligands (such as 2-phenylpyridine, etc.), it helps to suppress non-radiative decay pathways, produce high-efficiency luminescence, and strong thermodynamic stability. The heteronuclear bimetallic Pd-Pt dimer has good potential application value as a phosphorescent material in organic light-emitting diodes. Moreover, the heteronuclear bimetallic Pd-Pt dimer provided by the present invention is a novel phosphorescent material, which provides a new approach to solve the problems of limited types and single structure of existing phosphorescent materials, and has expanded the dimension of bimetallic materials in the field of phosphorescent materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Heteronuclear bimetallic Pd-Pt dimers C1, C2, C3, C4, C5, C9, C 11 、C 12 、C 13 Structural representation data structure diagram;

[0035] Figure 2 Thermogravimetric diagrams of heteronuclear bimetallic Pd-Pt dimers C1, C2, C3, C4, C8, and C9;

[0036] Figure 3 The UV-visible absorption spectra of heteronuclear bimetallic Pd-Pt dimers C1-C2 in solution at 25°C and the normalized emission spectra of C1-C2 in solution at 25°C are shown;

[0037] Figure 4is the normalized emission spectrum of heteronuclear bimetallic Pd-Pt dimer C1 in PMMA films with different mass fractions on a quartz plate at 25°C;

[0038] Figure 5 is the normalized emission spectrum of heteronuclear bimetallic Pd-Pt dimer C2 on a quartz plate in PMMA films with different mass fractions at 25°C;

[0039] Figure 6 is the normalized emission spectrum of heteronuclear bimetallic Pd-Pt dimers C1-C2 in solid powder state at 25°C;

[0040] Figure 7 is the normalized Raman spectra of heteronuclear bimetallic Pd-Pt dimers C1-C2 in solid powder state at 25°C;

[0041] Figure 8 Cyclic voltammograms of heteronuclear bimetallic Pd-Pt dimers C1 (left) and C2 (right);

[0042] Figure 9 EL characteristics of heteronuclear bimetallic Pd-Pt dimer C1 applied in OLEDs;

[0043] Figure 10 The current density-voltage-luminance characteristics of the heteronuclear bimetallic Pd-Pt dimer C1 applied to OLEDs;

[0044] Figure 11 EQE brightness characteristics of heteronuclear bimetallic Pd-Pt dimer C1 applied to OLEDs;

[0045] Figure 12 EL characteristics of heteronuclear bimetallic Pd-Pt dimer C2 applied in OLEDs;

[0046] Figure 13 The current density-voltage-luminance characteristics of the heteronuclear bimetallic Pd-Pt dimer C2 applied to OLEDs;

[0047] Figure 14 EQE brightness characteristics of heteronuclear bimetallic Pd-Pt dimer C2 applied to OLEDs;

[0048] Figure 15 Energy level diagram of heteronuclear bimetallic Pd-Pt dimer C1 and C2 devices and chemical structure diagram of the organic materials used in device preparation. DETAILED DESCRIPTION

[0049] The present invention provides a heteronuclear bimetallic Pd-Pt dimer having a structure shown in Formula I, Formula II or Formula III:

[0050]

[0051] In the formula I, formula II and formula III, Include any of the following structures:

[0052]

[0053] include

[0054] Include any of the following structures:

[0055]

[0056] wherein R1, R2, R3, R4 and R5 independently include hydrogen, fluorine, methyl, tert-butyl or phenyl; R1 is preferably hydrogen or phenyl; R2 is preferably hydrogen; R3 is preferably hydrogen; R4 is preferably hydrogen; R5 is preferably methyl; R6, R7, R8, R9 and R 10 R6 is preferably phenyl; R7 is preferably hydrogen; and X is CH or N.

[0057] In the present invention, the two Preferably different.

[0058] In the present invention, the heteronuclear bimetallic Pd-Pt dimer preferably has a structure represented by any one of Formulas I-1 to I-2, II-1 to II-8, and III-1 to III-8:

[0059]

[0060]

[0061] In the present invention, the heteronuclear bimetallic Pd-Pt dimer is more preferably of formula C1 to C 13 Any of the structures shown:

[0062]

[0063]

[0064] The heteronuclear bimetallic Pd-Pt dimer provided by the present invention is a dimer of palladium and platinum, and the ligand It is connected to Pd and Pt through coordination bonds.

[0065] The present invention provides a method for preparing the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution, comprising the following steps:

[0066] The bispalladium carboxylic acid dimer, the bisplatinum chloride bridge dimer, the dinitrogen ligand, the polar organic solvent (referred to as the first polar organic solvent) and the alkaline reagent are mixed to carry out a replacement reaction to obtain the heteronuclear bimetallic Pd-Pt dimer;

[0067] The double platinum chloride bridge dimer has a structure shown in any one of the following:

[0068]

[0069] The structural formula of the bispalladium carboxylic acid dimer is

[0070] in, With the formula I same;

[0071] The dinitrogen ligand Include any of the following structures:

[0072]

[0073] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0074] In the present invention, the bispalladium carboxylic acid dimer preferably has a structure shown in any one of Formula IX to Formula XIII:

[0075]

[0076]

[0077] In the present invention, the method for preparing the bispalladium carboxylic acid dimer preferably comprises the following steps: mixing a first ligand, palladium acetate and a second polar organic solvent, and performing a first addition reaction to obtain the bispalladium carboxylic acid dimer.

[0078] In the present invention, the first ligand preferably has a structure shown in any one of Formula IV to Formula VIII:

[0079]

[0080] in, Preferably including I - or Cl - .

[0081] In the present invention, the molar ratio of the first ligand to palladium acetate is preferably 1:1-1.2, more preferably 1:1.02-1.1.

[0082] In the present invention, the second polar organic solvent preferably includes toluene or 1,2-dichloromethane; when the first ligand is When the first ligand is other ligands, the second polar organic solvent is preferably toluene. When the first ligand is other ligands, the second polar organic solvent is preferably N,N-dimethylformamide. The present invention has no special requirements for the amount of the second polar organic solvent, as long as it can completely dissolve the first ligand.

[0083] In the present invention, when the first ligand has the structure shown in Formula VII, the first addition reaction is preferably carried out in the presence of silver oxide, and the molar ratio of the first ligand to the silver oxide is preferably 1:0.5-1, more preferably 1:0.6-0.8. In the present invention, the first ligand is preferably dissolved in a second polar organic solvent, silver oxide is added and stirred, and after cooling to room temperature, palladium acetate is added to carry out the first addition reaction. In the present invention, the stirring temperature is preferably 30-60°C, more preferably 40-50°C; the stirring time is preferably 12-48 hours, more preferably 20-24 hours. In the present invention, the temperature of the first addition reaction is preferably 100-120°C, more preferably 115°C; the time of the first addition reaction is preferably 12-24 hours, more preferably 12-15 hours.

[0084] In the present invention, when the first ligand has a structure shown in Formula IV, Formula V, Formula VI or Formula VIII, the temperature of the first addition reaction is preferably room temperature; the time of the first addition reaction is preferably 8 to 12 hours, more preferably 10 to 12 hours; the first addition reaction is preferably carried out under stirring conditions.

[0085] In the present invention, the preparation route of the bispalladium carboxylic acid dimer of the structure represented by Formula IX to Formula XIII is as follows:

[0086]

[0087] After completing the first addition reaction, the present invention preferably further comprises post-treatment, which preferably comprises: spin-drying the reaction mixture obtained from the first addition reaction, washing with diethyl ether, and then recrystallizing to obtain a bispalladium carboxylic acid dimer. The present invention has no particular requirements for the recrystallization, as long as the target product can be purified. In a specific embodiment of the present invention, the reaction mixture obtained from the first addition reaction is not post-treated, but is directly cooled to room temperature, and then a bisplatinum chloride bridge dimer is added under a protective atmosphere to synthesize a heteronuclear bimetallic Pd-Pt dimer; the protective atmosphere preferably comprises nitrogen, argon, or helium.

[0088] In the present invention, the double platinum chloride bridge dimer preferably has a structure shown in any one of Formula XIV to Formula XVIII:

[0089]

[0090] In the present invention, the preparation method of the double platinum chlorine bridge dimer preferably comprises the following steps: mixing a second ligand, a chlorine-containing platinum source and a third polar organic solvent, and performing a second addition reaction to obtain the double platinum chlorine bridge dimer.

[0091] In the present invention, the second ligand preferably has a structure represented by Formula IV, Formula V, Formula VI, Formula VII, or Formula VIII. In the present invention, the chlorine-containing platinum source preferably includes potassium tetrachloroplatinate or cyclooctadiene dichloroplatinum. In the present invention, the molar ratio of the second ligand to the chlorine-containing platinum source is preferably 1:1 to 1.1, more preferably 1:1.02 to 1.05.

[0092] In the present invention, the third polar organic solvent preferably includes ethylene glycol ethyl ether or N,N-dimethylformamide. The present invention has no particular requirements for the amount of the third polar organic solvent used, as long as it can completely dissolve the second ligand. In the present invention, when the second ligand has a structure represented by Formula IV, Formula V, Formula VI, or Formula VIII, the chlorine-containing platinum source is preferably potassium tetrachloroplatinate, and the third polar organic solvent is preferably ethylene glycol ethyl ether.

[0093] In the present invention, when the second ligand has the structure represented by Formula VII, the chlorine-containing platinum source is preferably cyclooctadiene platinum dichloride, and the third polar organic solvent is preferably N,N-dimethylformamide; the second addition reaction is preferably carried out in the presence of silver oxide. In the present invention, the molar ratio of the second ligand to the silver oxide is preferably 1:0.5-1, more preferably 1:0.6-0.8. In the present invention, the second ligand is preferably dissolved in the third polar organic solvent, silver oxide is added and stirred, and cyclooctadiene platinum dichloride is added after cooling to room temperature. In the present invention, the stirring temperature is preferably 40-70°C, more preferably 50-60°C, and the stirring time is preferably 5-12 hours, more preferably 6-8 hours.

[0094] In the present invention, the temperature of the second addition reaction is preferably 50-130°C; when the third polar organic solvent is ethylene glycol ethyl ether, the temperature of the second addition reaction is preferably 50-80°C, more preferably 70-80°C; when the third polar organic solvent is N,N-dimethylformamide, the second addition reaction is preferably first reacted at room temperature for 40-50 hours, then reacted at 100-130°C for 12-24 hours, more preferably first reacted at room temperature for 45-48 hours, then reacted at 120-130°C for 20-24 hours; the second addition reaction is preferably carried out under stirring. In the present invention, the preparation route of the double platinum chloride bridge dimer of the structure shown in Formula XIV to Formula XVIII is as follows:

[0095]

[0096] After completing the second addition reaction, the present invention preferably further comprises post-treatment, which preferably comprises: spin-drying the reaction mixture obtained from the second addition reaction, washing with ether, and then recrystallizing to obtain a bis-platinum chloride-bridged dimer. The present invention has no special requirements for the recrystallization, as long as the target product can be purified. In some embodiments of the present invention, the reaction mixture obtained from the first addition reaction is not post-treated, but is directly cooled to room temperature, and then a bis-palladium carboxylic acid dimer is added under a protective atmosphere to synthesize the heteronuclear bimetallic Pd-Pt dimer; the protective atmosphere preferably comprises nitrogen, argon, or helium.

[0097] In the present invention, the molar ratio of the bispalladium carboxylic acid dimer to the dinitrogen ligand is preferably 1:5 to 8, more preferably 1:6 to 8, and even more preferably 1:7 to 8. In the present invention, the molar ratio of the bisplatinum chloride bridge dimer to the dinitrogen ligand is preferably 1:5 to 8, more preferably 1:6 to 8, and even more preferably 1:7 to 8.

[0098] In the present invention, the alkaline agent preferably comprises an alkali metal alkoxide or potassium carbonate, wherein the alkali metal alkoxide preferably comprises sodium methoxide and / or potassium tert-butoxide; the potassium carbonate is preferably used only for synthesizing the heteronuclear bimetallic Pd-Pt dimer of the structure represented by Formula I. In the present invention, the molar ratio of the bispalladium carboxylic acid dimer to the alkaline agent is preferably 1:5-8, more preferably 1:6-8, and even more preferably 1:7-8. In the present invention, the molar ratio of the bisplatinum chloride bridge dimer to the alkaline agent is preferably 1:5-8, more preferably 1:6-8, and even more preferably 1:7-8.

[0099] In the present invention, the first polar organic solvent preferably includes N,N-dimethylformamide or 1,2-dichloroethane. The present invention has no particular limitation on the amount of the first polar organic solvent, as long as it can completely dissolve the dinitrogen ligand.

[0100] In the present invention, the temperature of the replacement reaction is preferably 50-120°C, more preferably 80-120°C or 50-90°C; the time of the replacement reaction is preferably 12-30h, more preferably 21-25h; the replacement reaction is preferably carried out under light-proof conditions; the replacement reaction is preferably carried out under a protective atmosphere, and the protective atmosphere preferably includes nitrogen, argon or helium.

[0101] In the present invention, the type of the first polar organic solvent and the temperature of the displacement reaction are preferably determined according to the type of the bis-palladium carboxylic acid dimer or the bis-platinum chloride bridge dimer. When the first polar organic solvent is preferably 1,2-dichloroethane; the temperature of the replacement reaction is preferably 50 to 90°C, more preferably 80 to 90°C; when the heteronuclear bimetallic Pd-Pt dimer does not contain a ligand When the first polar organic solvent is preferably N,N-dimethylformamide; the temperature of the replacement reaction is preferably 80 to 120°C, more preferably 100 to 120°C.

[0102] After the replacement reaction is completed, the present invention preferably removes the solvent from the resulting replacement reaction mixture and purifies it to obtain the heteronuclear bimetallic Pd-Pt dimer. In the present invention, the removal of the solvent preferably includes removing the solvent by rotary evaporation. In the present invention, the purification preferably includes column chromatography separation. The present invention has no particular requirements for the column chromatography separation, as long as it can purify the target product.

[0103] The present invention also provides the use of the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution or the heteronuclear bimetallic Pd-Pt dimer prepared by the preparation method described in the above technical solution in organic light-emitting diodes, catalysis, and pharmaceuticals. In the present invention, the heteronuclear bimetallic Pd-Pt dimer is preferably used as an emissive layer of an organic light-emitting diode. In the present invention, the heteronuclear bimetallic Pd-Pt dimer is preferably used as a catalyst to catalyze carbon-carbon and / or carbon-heteroatom bonding reactions, and the heteroatom preferably includes nitrogen, oxygen, or sulfur. In the present invention, the pharmaceutical preparation preferably includes the preparation of anticancer drugs.

[0104] The present invention also provides an organic light-emitting diode, wherein the emission layer material is the heteronuclear bimetallic Pd-Pt dimer described in the above technical solution or the heteronuclear bimetallic Pd-Pt dimer prepared by the preparation method described in the above technical solution.

[0105] The heteronuclear bimetallic Pd-Pt dimer provided by the present invention, its preparation method and application, and organic light emitting diode are described in detail below with reference to the examples. However, these examples should not be construed as limiting the scope of protection of the present invention.

[0106] Example 1

[0107] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C1 is as follows:

[0108]

[0109] The preparation steps are as follows:

[0110] (i) 0.48 mmol of ligand IV-2 was placed in a pressure bottle, and 6 mL of ethylene glycol ether was added. After dissolution, 0.48 mmol of potassium tetrachloroplatinate was added to the pressure bottle, and 1 mL of water was added to the pressure bottle. The mixture was stirred at 80°C for 12 h. After completion of the reaction, the resulting mixture was spin-dried, washed three times with ether, and recrystallized from dichloromethane / n-hexane to obtain the bis-platinum-chloro-bridged dimer XIV-2.

[0111] (ii) 4.51 mmol of ligand IV-1 was placed in a pressure bottle, 50 mL of dichloromethane was added, and 4.46 mmol of palladium acetate was added after dissolution. The mixture was stirred at room temperature for 5 h. After completion of the reaction, the resulting mixture was spin-dried, washed three times with diethyl ether, and recrystallized from dichloromethane / n-hexane to obtain bispalladium carboxylic acid dimer IX-1.

[0112] (iii) 10.06 mmol of the bis-platinum chloride-bridged dimer XII-, 10.06 mmol of the bis-palladium carboxylic acid dimer VIII-, 10.25 mmol of the bis-palladium carboxylic acid dimer XIX-, and 0.28 mmol of potassium carbonate were placed in an eggplant-shaped flask. 70 mL of 1,2-dichloroethane was added and the mixture was incubated at 90°C in the dark for 24 h. After completion of the reaction, the solvent was removed by rotary evaporation and the reaction mixture was purified by column chromatography (eluent: n-hexane / dichloromethane = 6:1) to obtain the heteronuclear bimetallic Pd-Pt dimer C1.

[0113] Example 2

[0114] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C2 is as follows:

[0115]

[0116] The preparation steps are the same as those in Example 1.

[0117] Example 3

[0118] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C3 is as follows:

[0119]

[0120] The preparation steps are as follows:

[0121] (i) Under nitrogen, 0.30 mmol of ligand VII-1 was placed in an eggplant-shaped flask, 5 mL of N,N-dimethylformamide was added, and after dissolution, 0.18 mmol of silver oxide was added. The mixture was stirred at 60°C for 6 h. The temperature was lowered and 0.30 mmol of cyclooctadiene platinum dichloride was added. The reaction was carried out at room temperature for 48 h. The reaction was then heated to 130°C for 21 h to obtain a mixture containing XVII-1. The mixture was cooled to room temperature without further treatment.

[0122] (ii) The preparation steps of IX-1 are the same as those in Example 1.

[0123] (iii) To the room temperature mixture containing XVII-1 were added IX-1 (0.15 mmol), XIX-1 (1.18 mmol), and potassium tert-butoxide (1.17 mmol). The mixture was incubated at 120°C in the dark for 24 h. After completion of the reaction, the solvent was removed by rotary evaporation and the mixture was purified by column chromatography (eluent: n-hexane / dichloromethane = 4:1) to obtain the heteronuclear bimetallic Pd-Pt dimer C3.

[0124] Example 4

[0125] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C4 is as follows:

[0126]

[0127] The preparation steps are the same as those in Example 3.

[0128] Example 5

[0129] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C5 is as follows:

[0130]

[0131] The preparation steps are the same as those in Example 3.

[0132] Example 6

[0133] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C6 is as follows:

[0134]

[0135] The preparation steps are the same as those in Example 3, except that in (iii), To participate in the reaction, 70 mL of 1,2-dichloroethane was added as a solvent and the reaction was carried out at a temperature of 90 °C.

[0136] Example 7

[0137] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C7 is as follows:

[0138]

[0139] The preparation steps are the same as those in Example 3. The difference is that in (iii), To participate in the reaction, 70 mL of 1,2-dichloroethane was added as a solvent and the reaction was carried out at a temperature of 90 °C.

[0140] Example 8

[0141] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C8 is as follows:

[0142]

[0143] The preparation steps are the same as those in Example 3.

[0144] Example 9

[0145] The synthetic route of heteronuclear bimetallic Pd-Pt dimer C9 is as follows:

[0146]

[0147] The preparation steps are the same as those in Example 3.

[0148] Example 10

[0149] Heteronuclear bimetallic Pd-Pt dimer C 10 The synthetic route is as follows:

[0150]

[0151] The preparation steps are the same as those in Example 3.

[0152] Example 11

[0153] Heteronuclear bimetallic Pd-Pt dimer C 11 The synthetic route is as follows:

[0154]

[0155] The preparation steps are the same as those in Example 3.

[0156] Example 12

[0157] Heteronuclear bimetallic Pd-Pt dimer C 12 The synthetic route is as follows:

[0158]

[0159] The preparation steps are as follows:

[0160] (i) Under nitrogen, 0.5 mmol of ligand VII-1 was placed in an eggplant-shaped flask. 3 mL of N,N-dimethylformamide was added and dissolved. 0.3 mmol of silver oxide was added and stirred at 50°C for 24 h. The mixture was cooled and added with 0.5 mmol of palladium acetate. The reaction was continued at 115°C for 12 h. After completion of the reaction, the mixture was cooled to room temperature without further treatment to obtain a mixture containing XII-1.

[0161] (ii) The preparation steps of IV-1 are the same as those in Example 1.

[0162] (iii) 10.5 mmol of IV-, 12 mmol of XIX-, and 2 mmol of potassium tert-butoxide were directly added to the mixture XII-1, which had been cooled to room temperature. The mixture was incubated at 90°C in the dark for 24 hours. After the reaction was complete, the solvent was removed by rotary evaporation and the mixture was purified by column chromatography (eluent: n-hexane / dichloromethane = 4:1) to obtain the heteronuclear bimetallic Pd-Pt dimer C. 12 .

[0163] Example 13

[0164] Heteronuclear bimetallic Pd-Pt dimer C 13 The synthetic route is as follows:

[0165]

[0166] The preparation steps are the same as those in Example 12.

[0167] Test Example 1

[0168] (1) Structure and performance characterization

[0169] 20 mg of heteronuclear bimetallic Pd-Pt dimer was dissolved in dichloromethane, filtered through an organic filter membrane, and added to a 20 mL sample bottle. An appropriate amount of n-hexane was then slowly added to the solution, and the solution was allowed to separate until it became slightly turbid. The solution was allowed to stand and slowly evaporate to grow suitable crystals. The experiment used an Agilent Technologies single crystal diffractometer and CCD area detector and an Oxford Cryosystems open flow freezer. Using graphite monochromated MoKα radiation The diffraction data of the crystal were collected at a temperature of 213.0°C and in the range of 7.76 to 110°θ. The data were subjected to absorption correction using the multi-scan method or numerical integration according to the actual crystal shape. The structure was solved using ShelXS6 and Olex -2 Optimization was performed using ShelXL7 using full-matrix least-squares optimization. Isotropic thermal parameters were used for hydrogen atoms, and anisotropic thermal parameters were used for non-hydrogen atoms. Thermal ellipsoids were drawn at a 30% probability level. Hydrogen atoms were omitted for clarity.

[0170] The heteronuclear bimetallic Pd-Pt dimers C1, C2, C3, C4, C5, C9, C 11 、C 12 and C 13 The molecular structure of Figure 1 .

[0171] Heteronuclear bimetallic Pd-Pt dimer C1 structural characterization data: 1H NMR (400MHz, Acetone-d6): δ8.30(s,1H),8.03(s,1H),7.63(m,4H),7.53(m,8H),7.41( m,6H),7.34(m,5H),7.19(m,8H),6.98(m,8H),6.75(m,3H),6.31(dd,1H),6.02(m,1H). 13 C NMR (100MHz, Acetone-d6): δ167.79,165.65,161.87,161.33,158.52,153.06,152.68,152.45,152.31,151. 71,151.45,149.66,146.72,146.63,142.95,138.45,137.98,135.87,135.68,134.52,130.35,130.00,129. 61,129.49,129.46,129.32,129.27,129.16,128.59,128.00,127.29,127.20,125.15,124.75,124.03,123.85,123.81,123.62,123.53,123.17,123.12,122.80,121.74,119.69,118.48,116.52,32.31,23.29,14.35. 195 Pt NMR(600MHz,Chloroform-d,):δ-3156.92.HR-MS(ESI):m / z calcd for C 60 H 46 N6PtPd[M+H] + :1152.2539; Found:1152.2537.Elemental analysis:Calc for C 60 H 46 N6PtPd: C, 60.81%; H, 3.96%; N, 7.03%; found: C, 61.06%; H, 3.593%; N, 6.92%.

[0172] Heteronuclear bimetallic Pd-Pt dimer C2 structural characterization data: 1H NMR(400MHz,Acetone-d6)δ8.44(s,1H),8.17(s,1H),7.79(d,1H),7.75(m,3H),7.69(m,3H),7.63(m,3H),7.58(m,8H),7.47(m,4H),7.39(s,1H),7.37(s,1H),7.34(m,7H),7.13(m,8H),6.88(m,3H),6.49(dd,1H),6.13(m,1H). 13 C NMR(100MHz,Acetone-d6):δ167.83,165.62,161.89,161.28,158.02,153.05,152.65,152.48,152.24,151.59,149.87,147.12,142.55,138.48,137.77,137.06,135.94,134.08,130.31,129.97,129.92,129.60,129.50,129.37,129.22,129.08,128.07,128.01,127.50,127.45,125.42,125.18,124.69,124.01,123.84,123.62,123.60,123.08,122.80,122.71,122.68,121.72,119.66,118.48,116.54,64.74,37.78,35.11,33.48,32.65,27.75,26.64,23.34,22.94,20.09,14.36. 195 Pt NMR(600MHz,Chloroform-d,23℃):δ-3179.00.HR-MS(ESI):m / z calcd for C 60 H 46 N6PtPd[M+H] + :1152.2539;Found:1152.2565.Elemental analysis:Calc for C 60 H 46 N6PtPd:C,62.53%;H,4.02%;N,7.29%;found:C,62.46%;H,3.629%;N,7.34%.ICP-OES:Calc for the molar ratio ofPd toPt is 1:1;found:Pd to Pt is 1:1.030.

[0173] Heteronuclear bimetallic Pd-Pt dimer C3 structural characterization data: 1 H NMR (400MHz, CD2Cl2, 23℃) δ8.45(s,1H),8.33(s,1H),7.63(m,3H),7.51(m,7H),7.31(m,9H ),7.11(m,5H),7.03(m,3H)6.90(m,5H),6.81(m,1H)6.63(t,2H),6.14(t,1H),2.75(s,3H). 13 C NMR (100MHz, Acetone-d6, 23℃): δ168.77,164.39,161.75,161.26,157.23,153.03,152.14,151.90,15 1.81,150.83,148.24,145.95,137.08,136.15,135.07,134.84,133.20,130.91,129.03,128.86,128.7 5,128.57,128.48,124.24,124.20,123.75,123.69,123.15,123.06,123.00,122.84,122.62,122.58, 122.44,122.25,120.97,116.98,111.84,110.95,110.79,31.98,31.93,23.05,14.28.HR-MS(ESI):m / z calcd for C 51 H 41 N7PtPd[M+H] + :1053.2179;Found:1053.2139.

[0174] Heteronuclear bimetallic Pd-Pt dimer C4 structural characterization data: 1H NMR(400MHz,CD2Cl2)δ8.45(s,1H),8.33(s,1H),7.95(m,1H),7.61(m,2H),7.50(m,6H),7.39(m,1H),7.2 9(m,8H),7.17(m,2H),7.11(m,4H),7.04(m,3H),6.89(m,5H),6.67(m,2H),6.18(m,1H),2.79(s,3H).13C NMR(100MHz,CD2Cl2)δ170.65,164.22,161.86,161.32,157.27,153.03,152.13,151.93,151.79,15 0.96,147.15,146.12,144.80,144.09,137.48,136.23,134.48,132.55,129.07,128.91,128.79,128 .59,128.56,127.81,124.72,124.29,124.26,123.67,123.26,123.14,123.08,123.04,122.73,122 .56,122.45,122.38,121.30,117.83,117.78,116.94,114.50,32.00,23.07,14.29.HR-MS(ESI):m / z calcd for C 50 H 40 N8PtPd[M] + :1053.2053;Found:1053.2083.

[0175] Heteronuclear bimetallic Pd-Pt dimer C5 structural characterization data: Crystallographic image see Figure 1 , HR-MS (ESI): m / zcalcdfor C 47 H 33 N7PtPd[M] + :996.1475; Found:996.1489.

[0176] Heteronuclear bimetallic Pd-Pt dimer C6 structural characterization data: 1H NMR (400MHz, CD2Cl2, 23℃) δ8.50(s,1H),8.38(s,1H),7.68(d,2H),7.53(m,11H),7.45(m, 4H),7.41(m,2H),7.35(m,1H),7.32(m,1H),7.30(s,1H),7.28(s,1H),7.26(d,1H),7.23( s,1H),7.22(m,1H),7.19(m,1H),7.15(m,2H),7.12(s,1H),7.10(s,1H),7.08(s,1H),7.0 6(m,1H),7.04(m,1H),6.99(m,5H),6.88(m,3H),6.82(m,1H),6.41(dd,1H),2.82(s,3H). 13 C NMR (100MHz, Acetone-d6, 23℃): δ13CNMR (101MHz, CD2Cl2) δ168.89,164.32,161.80,161.28,156.68,153.03,152.22,151.94,1 51.92,151.02,148.89,148.25,146.32,141.58,137.63,136.66,136.59,135.21,135.02,133.30,130.95,130.00,129.52,129. 12,129.06,128.95,128.79,128.53,127.27,127.22,127.00,124.41,124.36,124.28,123.80,123.25,123.16,123.05,122.73, 122.70,122.67,122.51,122.36,121.06,119.00,114.88,111.68,110.76,110.64,32.25,32.00,23.07,14.29.HR-MS(ESI):m / z calcd for C 63 H 49 N7PtPd[M+H] + :1205.2805;Found:1205.2701.

[0177] Heteronuclear bimetallic Pd-Pt dimer C7 structural characterization data: 1HNMR(400MHz, CDCl3)δ8.52(s,1H),8.36(s,1H),8.25(m,1H),7.89(m,1H),7.65(d,2H),7.55(m,8H),7.4 4(m,8H),7.36(m,4H),7.24(m,4H),7.12(m,8H),6.90(m,6H),6.35(m,1H),62.84(s,3H).HR-MS(ESI):m / z calcdfor C 62 H 48 N8PtPd[M+H] + :1206.2757;Found:1206.2721.

[0178] Heteronuclear bimetallic Pd-Pt dimer C8 structural characterization data: 1 H NMR (400MHz, CD2Cl2, 23℃) δ8.51(s,1H),8.39(s,1H),7.71(d,3H),7.55(m,7H),7.42(m,2H),7.30(m,4H), 7.22(m,3H),7.13(m,7H),7.02(s,1H),7.00(t,1H),6.89(m,6H),6.60(d,1H),6.55(dd,1H),2.63(s,3H). 13 C NMR (100MHz, Acetone-d6, 23℃): δ168.10,161.87,161.36,154.93,154.44,153.09,152.21,152.17,1 49.73,147.92,141.57,135.42,134.80,134.46,133.24,133.01,132.97,130.11,129.09,128.93,128 .76,128.51,127.96,127.73,126.03,124.39,124.32,124.15,123.60,123.25,123.11,123.02,122. 79,122.74,122.69,122.45,122.34,121.84,120.80,111.64,110.61,110.59,31.82.HR-MS(ESI):m / z calcd for C 51 H 41 N7PtPd[M+H] + :1077.2179;Found:1077.2123.

[0179] Heteronuclear bimetallic Pd-Pt dimer C9 structural characterization data: 1 HNMR(400MHz, CDCl3)δ8.56(s,1H),8.42(s,1H),8.16(m,1H),7.74(d,4H),7.60(m,6H),7.45(d,2 H),7.37(m,1H),7.32(d,2H),7.29(m,1H),7.25(m,2H),7.14(m,15H),6.53(dd,1H),2.57(s,3H). 13 C NMR (100MHz, CDCl3) δ170.04,161.65,161.21,154.81,153.86,152.84,

[0180] 132.87,132.56,131.89,128.99,128.69,128.67,128.28,127.77,126.90,126.61,125.61,124.51,124.15,124.12,123.20,123.08,1 22.88,122.72,122.63,122.60,122.16,122.10,121.49,120.78,117.18,116.80,114.30,31.81,31.72,22.79,14.28.HR-MS(ESI):m / z calcd for C 52 H 40 N8PtPd[M+H] + :1078.2131;Found:1078.2107.

[0181] Heteronuclear bimetallic Pd-Pt dimer C 10 Structural characterization data: 1 H NMR(400MHz,CD2Cl2)δ8.79(m,1H),8.55(d,1H),8.40(d,1H),8.16(m,1H),7.97(m,1H),7.82(dd,1H),7.70(m,2H),7.63(m,2H),7 .52(m,8H),7.33(m,3H),7.26(m,3H),7.13(m,5H),7.01(m,1H),6.95(m,5H),6.79(d,1H),6.61(m,1H),6.50(m,2H),2.74(d,3H). 13C NMR(100MHz,CD2Cl2)δ167.65,161.74,161.37,157.13,152.86,152.07,152.03,151.87,148.83,147.86,14 3.11,143.10,142.28,139.32,134.93,134.20,133.93,133.13,132.30,131.18,129.61,129.53,129.20,129 .14,129.08,128.84,128.58,127.36,125.04,124.45,124.41,124.33,123.49,123.40,123.36,123.32,122 .97,122.63,122.59,122.55,122.51,117.51,111.76,110.22,110.11,32.10,23.07,14.29.HR-MS(ESI):m / z calcd for C 56 H 42 N8PtPd[M+H] + :1128.2288;Found:1128.2246.

[0182] Heteronuclear bimetallic Pd-Pt dimer C 11 Structural characterization data: 1 H NMR(400MHz, CDCl3)δ8.85(m,1H),8.55(s,1H),8.38(s,1H),8.17(m,1H),7.97(d,1H),7.88(d,1H),7.77(m,1H),7.7 0(d,2H),7.62(m,4H),7.54(m,3H),7.47(m,8H),7.14(m,10H),6.93(m,2H),6.62(m,1H),6.35(dd,1H),2.59(s,3H). 13C NMR (100MHz, CDCl3) δ169.41,161.57,161.27,157.23,152.62,151.51,151.47,148.19,146.41,143.34 ,143.13,142.95,141.81,139.18,134.41,133.87,131.68,130.78,129.24,129.12,128.95,128.86,128 .75,128.66,128.35,127.17,126.22,125.30,124.69,124.19,124.04,123.51,123.43,123.34,122.72 ,122.69,122.49,122.37,117.09,117.06,116.39,114.63,31.90,31.72,22.79,14.28.HR-MS(ESI):m / z calcd forC 55 H 41 N9PtPd[M+H] + :1129.2240;Found:1129.2218.

[0183] Heteronuclear bimetallic Pd-Pt dimer C 12 Structural characterization data: 1 H NMR(400MHz,CD2Cl2)δ8.41(s,1H),8.19(s,1H),8.03(m,1H),7.78(m,1H),7.63( d,1H),7.59(d,2H),7.52(m,1H),7.50(s,1H),7.48(s,1H),7.46(s,2H),7.44(s, 1H),7.42(m,1H),7.33(m,1H),7.26(m,6H),7.10(m,5H),7.03(d,1H),6.99(m,2H ),6.94(m,2H),6.88(m,3H),6.77(m,1H),6.61(m,2H),6.10(m,1H),2.81(s,3H).

[0184] Heteronuclear bimetallic Pd-Pt dimer C 13 Structural characterization data: 1H NMR (400MHz, CD2Cl2) δ8.44(d,1H),8.32(d,1H),8.00(m,2H),7.69(m,5H),7.54(m,10H),7.37(m,3H),7. 27(m,14H),6.97(m,1H),6.90(m,3H),6.74(m,2H),6.63(d,1H),6.47(d,1H),6.15(ddd,1H),2.84(d,3H).

[0185] (2) Thermal stability test

[0186] The complexes were subjected to thermogravimetric analysis (TGA) tests at a heating rate of 10°C / min from 35°C to 800°C under a nitrogen atmosphere. The thermogravimetric analysis curves of six complexes (C1, C2, C3, C4, C8, and C9) were obtained. Figure 2 Complex C1 began to decompose after 200°C, and complex C9 after 343°C. Complexes C2, C3, C4, and C8 all began to decompose after 310°C, demonstrating the feasibility of these complexes in the fabrication of OLED devices using vapor deposition methods and their potential applications in a wider range of optoelectronic fields.

[0187] (3) Photophysical properties test

[0188] The heteronuclear bimetallic Pd-Pt dimers prepared in each example were prepared in ACS grade dichloromethane to a concentration of 1.0×10 -5 mol / L sample solution was prepared, and the UV absorption spectrum of the dimer was measured on an Agilent Cary 100 UV-Vis spectrophotometer. The emission spectrum, phosphorescence lifetime, and quantum yield of the dimer were measured using an Edinburgh Instruments FLS1000 steady-state transient fluorescence spectrophotometer. Emission spectra were obtained using a xenon lamp with excitation and emission slit widths of 1.0 nm and 1.0 nm, respectively, at the wavelength of maximum absorption. PMMA films were prepared by dissolving heteronuclear bimetallic Pd-Pt dimer and poly(methyl methacrylate) (PMMA) in ACS-grade dichloromethane at four mass ratios: 1:99, 1:48, 1:9, and 1:4. Appropriate amounts of the solution were then dropwise applied to 1×1 cm quartz slides to form thin films, which were then thoroughly dried for testing. Absolute quantum yields and phosphorescence lifetimes were measured using an integrating sphere on an Edinburgh FLS1000 steady-state transient fluorescence spectrophotometer. Before measurement, the sample was degassed by three freeze-pump-thaw cycles and bubbling with nitrogen three times for approximately 10 minutes each to remove oxygen from the solution. The key photophysical performance indicators of the heteronuclear bimetallic Pd-Pt dimers C1 and C2 are summarized in Table 1.

[0189] The heteronuclear bimetallic Pd-Pt dimers C1-C2 were dissolved in dichloromethane respectively, and their UV-visible absorption spectra and normalized emission spectra were measured at 25°C. The results are shown in Figure 3 .

[0190] The normalized emission spectra of heteronuclear bimetallic Pd-Pt dimers C1-C2 were measured on a quartz plate with 1wt%, 2wt%, 10wt% and 20wt% mass fraction PMMA films at 25°C (2wt% refers to the mass ratio of heteronuclear bimetallic Pd-Pt dimer to PMMA). The results are shown in Figure 4 and Figure 5 .

[0191] The normalized emission spectra of heteronuclear bimetallic Pd-Pt dimers C1-C2 were measured at 25°C in solid powder state. Figure 6 .

[0192] Table 1 Photophysical properties of heteronuclear bimetallic Pd-Pt dimers C1-C2

[0193]

[0194] Note: a Maximum value of the electronic absorption band in CH2Cl2 at room temperature (λ abs ) and molar absorption coefficient (logε). b Measured in N2-degassed CH2Cl2. c Measured in 1wt%, 2wt%, 10wt%, and 20wt% PMMA films on a quartz plate. d Phosphorescence quantum yield measured using an integrating light sphere. e Estimated radiation rate constant (k) by using the following equation r ) and the non-radiative rate constant (k nr ):k r =φ / τ,k nr =(1-φ) / τ.

[0195] From Table 1 and Figures 3 to 6Complexes C1 and C2 exhibit strong structure-bound emission in N₂-degassed dichloromethane at room temperature, with maximum wavelengths around 669 nm, respectively. This is attributed to the structural similarity of the two complexes. The excitation and emission peaks of the lowest energy absorption band exhibit a 199 nm Stokes shift. Complexes C1 and C2 exhibit similar red triplet emission in degassed CH₂Cl₂. The large Stokes shift (>100 nm) and long emission lifetimes in the microsecond region support triplet emission. Furthermore, both complexes exhibit strong phosphorescence in both powder and PMMA films. The emission spectra of C1 and C2 in powder form exhibit a peak at 669 nm. The emission of the complexes in 1 wt%, 2 wt%, 10 wt%, and 20 wt% PMMA concentrations shifts from 640 nm to 654 nm in the red, approaching the emission wavelength of the pure powders. We conclude that some intermolecular interactions exist between the complexes in the powders, but these interactions are weak. The emission wavelengths of C1 and C2 are very similar, indicating that ligand exchange has little effect on the photophysical properties of the complexes. To further elucidate the photophysical properties of these two complexes, the absolute photoluminescence quantum yield (PLQY) and decay lifetime of each complex were studied in solution, pure powder, and PMMA film. For complexes C1 and C2, the PLQYs were 0.13 and 0.15, respectively, in dichloromethane. In the pure powder state, the PLQYs of C1 and C2 increased to 0.22 and 0.25, respectively. The highest PLQYs of complexes C1 and C2 in PMMA films containing 1 wt%, 2 wt%, 10 wt%, and 20 wt% concentrations were 0.14 and 0.18, respectively. The excited-state lifetimes ranged from 1.48 to 30 μs, supporting the radiative decay of triplet excited states.

[0196] Raman spectroscopy: To obtain direct evidence for the existence of Pd-Pt bonds, the Raman spectra of complexes C1 and C2 were measured using an excitation wavelength of 785 nm. After correction and subtraction of the Rayleigh line and the glass band, Figure 7 The Raman spectra of the pure solid state of complexes C1 and C2 are shown. The Pd-Pt stretching vibration frequency of complexes C1 and C2 is 100 cm -1 This proves the existence of Pd-Pt interaction.

[0197] (4) Electrochemical property test

[0198] The electrochemical properties of heteronuclear bimetallic Pd-Pt dimers C1-C2 were tested by cyclic voltammetry at room temperature (298K) in a N2 atmosphere using a CHI760e and a standard three-electrode test system. A glassy carbon electrode was used as the working electrode, a platinum wire electrode was used as the auxiliary electrode, and an Ag / Ag +The electrode was used as a reference electrode. The supporting electrolyte was n-Bu4NPF6, ferrocene was used as the internal standard, and the scan rate was 100 Vs -1 Utilize Fc + / Fc relative half-wave potential E HOMO [eV]=-(E ox '+4.8)eV to calculate the ionization potential of heteronuclear bimetallic Pd-Pt dimers C1 and C2. LUMO By E LUMO [eV]=E HOMO +E g Calculated. Among them, E ox '=E onset -E 1 / 2ferrocene Relative to Fc + The onset oxidation potential E of Fc was measured by CV peak. onset , using the empirical relationship E 1 / 2ferrocene =(E pc +E pa ) / 2 was used to estimate the redox potential of ferrocene. pc and E pa Represent the redox potential of ferrocene. Using the longest absorption wavelength λ onset To calculate the band gap energy E g =hc / λ onset , where h is Planck's constant, λ is the onset time of composite absorption, and c is the speed of light in vacuum. The key electrochemical properties of heteronuclear bimetallic Pd-Pt dimers C1 and C2 are shown in Figure 8 , the indicators are summarized in Table 2.

[0199] Table 2 Electrochemical parameters of heteronuclear bimetallic Pd-Pt dimers C1-C2

[0200] dimer <![CDATA[E ox (V)]]> <![CDATA[E HOMO a (eV)]]> <![CDATA[E LUMO b (eV)]]> <![CDATA[E g c (eV)]]> <![CDATA[C1]]> +0.33 / +0.468 / +0.892 / +1.062 -4.944 -2.297 +2.638 <![CDATA[C2]]> +0.324 / +0.472 / +0.827 / +1.018 -4.928 -2.29 +2.638

[0201] Notes: a HOMO energy level calculated from CV data using ferrocene as an internal standard. b LUMO energy level calculated by cyclic voltammetry and UV-Vis spectroscopy. c Optical band gap from the absorption spectrum in degassed CH2Cl2, determined by Eg = hc / λ.

[0202] The electrochemistry of C1 and C2 in dichloromethane was studied by cyclic voltammetry. The half-wave oxidation potential (vs Fc / Fc + ) was used to determine the HOMO energy levels of C1 and C2, and their LUMO energy levels were obtained by subtracting the optical band gap energy measured by UV-visible absorption spectroscopy from the HOMO energy levels. The calculation results are shown in Table 2. Figure 8Complexes C1 and C2 exhibit two reversible oxidation peaks at +0.33 / +0.468 / +0.892 / +1.062 V and +0.324 / +0.472 / +0.827 / +1.018 V, respectively. The oxidation peaks for all complexes are tentatively attributed to the oxidation of 2-([1,1'-biphenyl]-3-yl)-4-phenylpyridine and the 2-phenylpyridine-chelated Pt core. The HOMO levels of complexes C1 and C2 are -4.944 eV and -4.928 eV, respectively, and the LUMO levels are -2.297 eV and -2.29 eV, respectively. Both complexes exhibit similar HOMO and LUMO levels. These results indicate that the exchange of ligands bound to the Pt and Pd metals has no significant effect on the oxidation potential. Notably, both complexes C1 and C2 exhibit reversible electrochemical oxidation, primarily occurring at the phenylpyridine moiety.

[0203] (5) OLED device performance test

[0204] OLED devices were prepared and performance tested for the heteronuclear bimetallic Pd-Pt dimers prepared in each embodiment. A vapor deposition process was selected to manufacture the OLED devices. The structure of the OLED device was ITO / HAT-CN (6nm) / HAT-CN (0.3wt%): TAPC (50nm) / TCTA: C1 / C2 (10nm) / 26DCzPPy: C1 / C2 (10nm) / Tm3PyP26PyB (60nm) / LiF (1nm) / Al (100nm). In the device, the HAT-CN film was selected as the hole injection layer (HIL), and a TAPC film doped with HAT-CN (0.3wt%) was prepared as the hole transport layer / electron blocking layer (HTL / EBL). As a double-light-emitting layer device, TCTA and 26DCzPPy were used as the main materials in the emission layer (EmL). C1 and C2 were used as the emission materials of the EmL, doped with different concentrations of the main materials. Tm3PyP26PyB was used as the electron transport layer (ETL) due to its excellent electron mobility and low highest occupied molecular orbital (HOMO) energy level (-6.5eV). The EL characteristics of the device are shown in Figure 2. Figure 9 (C1) and Figure 12 (C2), current density-voltage-brightness characteristic diagram see Figure 10 (C1) and Figure 13 (C2), EQE brightness characteristic diagram see Figure 11 (C1) and Figure 14 (C2). The energy level diagram of the device and the chemical structure of the organic materials used in the device preparation are as follows Figure 15 The key performance indicators of OLED devices of compounds C1 and C2 are summarized in Table 3.

[0205] Table 3 Key performance indicators of OLED devices of heteronuclear bimetallic Pd-Pt dimers C1-C2

[0206]

[0207] Note: a Maximum brightness. b Maximum value. c At 10mA / cm 2 CIE coordinates at d 100cd / m 2 The maximum peak of EL emission is 100cd / m 2 The FWHM of the EL emission peak at .

[0208] As shown in Table 3, C1 has a quantum efficiency of 25% in the pure solid state and a triplet lifetime of 4.18 μs in a 2 wt% PMMA film. Complex C2 has a quantum efficiency of 22% in the pure solid state and a triplet lifetime of 2.50 μs in a 2 wt% PMMA film. Given their superior quantum efficiencies, these two complexes were selected as emissive materials for fabricating OLED devices.

[0209] OLED devices were fabricated using a vapor deposition process. The structures of the OLED devices exhibiting red-orange emission were ITO / HAT-CN (6 nm) / HAT-CN (0.3 wt%):TAPC (50 nm) / TCTA:C1 or TCTA:C2 (10 nm) / 26DCzPPy:C1 or 26DCzPPy:C2 (10 nm) / Tm3PyP26PyB (60 nm) / LiF (1 nm) / Al (100 nm), where 6 nm, 50 nm, 10 nm, 10 nm, 60 nm, 1 nm, and 100 nm represent thicknesses. The mass fractions of C1 in TCTA:C1 were 2%, 3%, and 5%, respectively, and the mass fractions of C2 in TCTA:C2 were 2%, 4%, and 6%, respectively. The mass fractions of C1 in 26DCzPPy:C1 were 2%, 3%, and 5%, respectively, and the mass fractions of C2 in 26DCzPPy:C2 were 2%, 4%, and 6%, respectively. In these devices, pure 1,4,5,8,9,11-hexaazatriphenylhexacarbonitrile (HAT-CN) film was selected as the hole injection layer (HIL), and di-[4-(N,N-diamino)-phenyl]cyclohexane (TAPC) film doped with HAT-CN (0.3 wt %) was prepared as the hole transport layer / electron blocking layer (HTL / EBL). As a dual-emission layer device, 4,4',4"-tris(N-carbazolyl)triphenylamine (TCTA) and 2,6-bis(3-(9H-carbazolyl-9-yl)phenyl)pyridine (26DCzPPy) were used as host materials in the emissive layer (EML). Complexes C1 and C2 were used as the emissive materials of the EML, doped with different concentrations of the host materials. 3,5-Tris(6-(3-(pyridin-3-yl)phenyl)pyridin-2-yl) (Tm3PyP26PyB) was used as the electron transport layer (ETL) due to its excellent electron mobility and low highest occupied molecular orbital (HOMO) energy level (-6.5 eV). LiF and Al were used as the cathode.

[0210] Complexes C1 and C2 were doped into TCTA and 26DCzPPy, respectively, at different concentration ranges. For devices based on C1, no significant host emission was observed in devices at all concentrations, indicating that energy transfer from the host to C1 was efficient and that intermolecular interactions between the compounds were effectively suppressed by their bulky ligands. At a lower concentration of 2 wt%, the emission from both hosts, TCTA and 26DCzPPy, in the EL spectrum of complex C2 indicated insufficient energy transfer from the host to the emitter, resulting in relatively low efficiency at lower dopant concentrations. As the doping concentration increased, the main emission in the device disappeared, thereby improving the efficiency of the device. At a certain driving voltage, the current density of both devices decreased with decreasing doping concentration, indicating that direct capture may be the main emission mechanism. In addition, the brightness of both devices increased with increasing doping concentration. When the doping concentration was 4 wt%, maximum EQEs of 10.7% and 10.1% were obtained in C1-based and C2-based devices, respectively, and the brightness gradually increased to 6734 cd / m 2 and 6004cd / m 2 .

[0211] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A heteronuclear bimetallic Pd-Pt dimer having the structure shown in Formula I-1: ； in, R1 is hydrogen, fluorine, methyl, tert-butyl or phenyl; R6 is methyl, tert-butyl or phenyl.

2. The method for preparing the heteronuclear bimetallic Pd-Pt dimer according to claim 1, comprising the following steps: mixing a bispalladium carboxylic acid dimer, a bisplatinum chloride bridge dimer, a dinitrogen ligand, a polar organic solvent and an alkaline reagent, and performing a replacement reaction to obtain the heteronuclear bimetallic Pd-Pt dimer; The double platinum chloride bridge dimer has the following structure: ; The bispalladium carboxylate dimer has the following structure: ; The dinitrogen ligand has the following structure: ; Wherein, R1 is hydrogen, fluorine, methyl, tert-butyl or phenyl; R6 is methyl, tert-butyl or phenyl.

3. The preparation method according to claim 2, characterized in that The molar ratio of the bispalladium carboxylic acid dimer to the bisplatinum chloride bridge dimer is 1:

1.

4. The preparation method according to claim 2, characterized in that The polar organic solvent is N,N-dimethylformamide or 1,2-dichloroethane.

5. The preparation method according to any one of claims 2 to 4, characterized in that The temperature of the replacement reaction is 50-120° C., and the time is 12-30 hours; the replacement reaction is carried out in a light-proof and protective atmosphere.

6. Use of the heteronuclear bimetallic Pd-Pt dimer according to claim 1 in an organic light-emitting diode.

7. An organic light emitting diode, characterized in that: The emission layer material is the heteronuclear bimetallic Pd-Pt dimer described in claim 1.

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