Divalent platinum complex with adjustable luminescence spectrum, preparation method and application thereof as yellow phosphorescent material in organic optoelectronic device

Abstract

The present invention belongs to the technical field of organic electroluminescent materials, and specifically relates to a preparation method of a class of organic metal platinum complexes, and a light-emitting device and application thereof. The present invention introduces a bipyridine N^C coordination structure into the ligand structure of a divalent platinum complex, and the yellow phosphorescence emission peak of the obtained tetradentate ligand-coordinated platinum heterocomplex is controlled between 550-570nm, and the half-peak width is adjustable from 36 to 147nm. It is a class of high-efficiency yellow phosphorescent materials with adjustable spectrum, which can be used in the preparation of electroluminescent applications related to yellow phosphorescent light-emitting devices, and can also be combined with blue light devices to manufacture white phosphorescent devices and applied to lighting or display.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent materials, and specifically relates to a divalent platinum complex and a preparation method thereof, as well as application of the divalent platinum complex as an electroluminescent material in an organic photoelectric device. Background Art

[0002] Organic light-emitting diodes (OLEDs) can be used in the next generation of lighting and display fields due to their surface emitting, flexibility, thinness, close to sunlight, low blue light and no glare hazards. In terms of luminescence, yellow is a "combination" color. It is not one of the three primary colors of "RGB". It is a light color composed of equal amounts of red light and green light. Therefore, in color science, yellow phosphorescence is formed by filtering out blue light from white phosphorescence, and it is often the complementary color of blue light. Therefore, the mutual cooperation of blue light and yellow phosphorescence can be used to form a white phosphorescence light source with high efficiency and high stability. Therefore, high-efficiency yellow phosphorescence luminescent materials and devices have practical application value in display, lighting and special yellow light lamps. Organic divalent platinum complexes coordinated by tetradentate ligands have the characteristics of good spectral regulation performance, high efficiency and potential high stability, so they can be explored to prepare organic light-emitting diode devices with suitable luminescence spectra. For specific spectral tunable performance characteristics, please refer to the public technical literature: Triplet Excited-State Engineering of Phosphorescent Pt(II) Complexes Yipei Wu, Xiao Tan, Anqi Lv, Feiling Yu, Huili Ma, Kang Shen, Zhengyi Sun, Fei Chen, Zhi-Kuan Chen, and Xiao-Chun Hang J. Phys. Chem. Lett. 2019, 10, 5105-5110. For specific characteristics of divalent platinum complexes that can be used to prepare stable light-emitting devices, please refer to the public technical literature: Efficient and stable organic light-emitting devices employing phosphorescent molecular aggregates Linyu Cao, Kody Klimes, Yunlong Ji, Tyler Fleetham and JianLi, Nature Photonics 2021, 15, 230-237.

[0003]

[0004] Patent CN 112125932 A discloses a Pt-C py High-performance yellow phosphorescent material with a structure of C py The coordinated pyridine appears as an electron donor in the overall molecule. This design has the characteristics of reverse application of functional group electrical properties. Its internal complex structure is three consecutive 5-6-6-membered platinum metal rings. This structure generally has a large degree of distortion, thus showing the characteristics of molecular monomer luminescence. In addition to the luminescence of the molecular monomer, the 5-6-5-membered platinum metal ring can also produce aggregated luminescence energy levels at higher concentrations, thereby obtaining luminescence properties at lower photon energy. The specific theory and its potential functional change characteristics can be referred to the public technical literature: Probing Triplet Excited States and Managing Blue Light Emission of Neutral Tetradentate Platinum (II) Complexes Cong You, Fang Xia, Yue Zhao, Yin Zhang, Yongjian Sheng, Yipei Wu, Xiao-Chun Hang, Fei Chen, Huili Ma, Kang Shen, Zhengyi Sun, Takahiro Ueba, Satoshi Kera, Cong Zhang, Honghai Zhang, Zhi-Kuan Chen, and Wei Huang J. Phys. Chem. Lett. 2018, 9, 2285-2292. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a divalent platinum complex and a preparation method thereof. The divalent platinum complex can be used as a high-efficiency yellow phosphorescent luminescent material. The half-peak width of the luminescent spectrum of this type of material can be greatly adjusted and has huge application space in the fields of display and lighting.

[0006] The divalent platinum complex disclosed in the present invention has a structure described by formula (I):

[0007]

[0008] Among them, R a , R c and R d are each independently a monosubstituted or disubstituted group, and R a , R c and R d are each independently selected from a monoatom substituent or a polyatom substituent; R b , R eare substituents each independently containing at least one carbon atom; the monoatomic substituents include hydrogen atoms, isotope atoms thereof or halogen atoms; the polyatomic substituents are alkyl or aryl substituents of 1 to 14 carbon atoms, including alkyl, aryl-substituted alkyl, fluorine-substituted alkyl, aryl, alkyl-substituted aryl, aryl-substituted aryl, or the above-mentioned substituents containing isotope atoms.

[0009] Furthermore, R a , R c and R d can be independently selected from a hydrogen atom, a deuterium atom, and a fluorine atom; R a , R b , R c , R d , R e selected from deuterated or non-deuterated methyl, benzyl, diphenylmethyl, triphenylmethyl; ethyl, 2-phenylethyl, 2,2-phenylethyl, 2,2,2-trifluoroethyl; propyl, isopropyl, 3,3,3-trifluoropropyl, 1,1,1,3,3,3-hexafluoro-2-propyl; n-butyl, isobutyl, hexafluoroisobutyl, tert-butyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl; phenyl, 2-methylphenyl, 2-isopropylphenyl, 2-ethylphenyl, 4-methylphenyl phenyl, 4-isopropylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 2,3-dimethylphenyl, 2,3-diethylphenyl, 2,3-diisopropylphenyl, 2,3-diisobutylphenyl, 2,3-dicyclohexylphenyl, 2,3-dicyclopropylphenyl, 2,3-dicyclobutylphenyl, 2,3-dicyclopentylphenyl, 2,4-dimethylphenyl, 2,4-diethylphenyl, 2,4-diisopropylphenyl, 2,4-diisobutylphenyl, 2,4-dicyclohexylphenyl phenyl, 2,4-dicyclopropylphenyl, 2,4-dicyclobutylphenyl, 2,4-dicyclopentylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,6-diisobutylphenyl, 2,6-dicyclohexylphenyl, 2,6-dicyclopropylphenyl, 2,6-dicyclobutylphenyl, 2,6-dicyclopentylphenyl, 3,5-dimethylphenyl, 3,5-diethylphenyl, 3,5-diisopropylphenyl, 3,5-diisobutylphenyl Phenyl, 3,5-dicyclohexylphenyl, 3,5-dicyclopropylphenyl, 3,5-dicyclobutylphenyl, 3,5-dicyclopentylphenyl, 2,3,5,6-tetramethylphenyl, 2,4,6-trimethylphenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 2,4,6-triisobutylphenyl, 2,4,6-tricyclohexylphenyl, 2,4,6-tricyclopropylphenyl, 2,4,6-tricyclobutylphenyl, 2,4,6-tricyclopentylphenyl.

[0010] The divalent platinum complex is selected from the structure of one of the following complexes 1 to 90:

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] Furthermore, in the above divalent platinum complex, R a , R c and R e is a hydrogen atom, R e is selected from alkyl and aryl; R a , R c and R d is a hydrogen atom, R b Selected from alkyl and aryl.

[0018] The present invention also provides a general synthesis method of the above-mentioned divalent platinum complex, and the specific steps are as follows:

[0019]

[0020] Step 1: Go through the 4-Rs a Substituted pyridyl-2,6-dichloro, bromo, iodo or trifluoromethanesulfonate substituted pyridine as the basic unit for coupling;

[0021] Step 2: performing two-step coupling reaction to obtain corresponding fragment coupling intermediates, wherein the two-step coupling reaction includes any one of Ullmann coupling, Buchwald-Hartwig coupling reaction or similar coupling reaction;

[0022] The third step: imidazole ring-closing reaction, specifically, under the action of a fluorine-containing anion salt, the coupled intermediate and trialkyl orthoformate are condensed into a ring in one step to obtain a precursor of the final product ligand, wherein the fluorine-containing anion of the precursor includes hexafluorophosphate anion, tetrafluoroborate anion, trifluoromethanesulfonate anion or trifluoromethanesulfonimide anion;

[0023] Step 4: Synthesis of divalent platinum complex: By reacting the ligand precursor and the divalent platinum complex at above 80°C, the divalent platinum complex can be directly obtained, wherein the divalent platinum compound can be potassium tetrachloroplatinite, (1,5-cyclooctadiene) platinum dichloride, platinum dichloride, etc.

[0024] In addition, the present invention also provides the use of the divalent platinum complex as an electroluminescent material or a photoluminescent material.

[0025] Optionally, the divalent platinum complex of the present invention can be used as a yellow phosphorescent material or a phosphorescent material in an organic optoelectronic device.

[0026] The beneficial effects of the present invention are as follows: relative to the prior art, the present invention provides a wide-spectrum yellow phosphorescent luminescent material by introducing bipyridine into the ligand of the divalent platinum complex, wherein one pyridine ring forms a C-Pt metal bond with the metal center through a carbon atom. In the embodiment of the present invention, the disclosed divalent platinum complex molecule coordinated by a neutral tetradentate ligand containing a bipyridine structure can emit yellow phosphorescence as a phosphorescent luminescent material, and the peak wavelength of the yellow phosphorescence is in the range of 550 to 580 nm, and the luminescence range can be covered between 510 and 700 nm, and has good stability and high efficiency, and is completely suitable as an organic yellow phosphorescent luminescent body in OLED-related products. From the implementation of this patent, when the substituent on the pyridoimidazole is 2,6-diisopropylphenyl, due to the steric hindrance and vibration restriction effects, the molecule exhibits single-molecule luminescence performance; when it is isopropyl, there is an aggregated luminescence effect, which can be adjusted to a wide spectrum of yellow light; the explanation of the specific relevant theory can refer to the public literature: Lu Zhu, Wentao Xie, Chunyue Qian, Wang Xie, Kang Shen, Anqi Lv, Huili Ma, Hongbo Li, Xiao-Chun Hang, * Wenqi Li, Shi-Jian Su, * and Wei Huang * Tetradentate Pt (II) Complexes for Spectrum-Stable Deep-Blue and White Electroluminescence Adv. Optical Mater. 2020, 2000406. The free N atom ortho-substituent in the bipyridine N^C coordination structure has a regulating effect on the single-molecule luminescence of the luminescence spectrum, that is, the freely rotating phenyl group can make the luminescence spectrum wider, thereby regulating the span of the yellow light luminescence region. Therefore, the three embodiments of this patent realize the change of the solid-state yellow phosphorescence spectrum within the range of half-peak width 39 to 147nm. In addition, the divalent platinum complex provided by the present invention is easy to prepare and sublimate and purify, is soluble in general organic solvents, and is suitable for device processes processed by both evaporation and solution methods. The luminescent properties of this type of material have the characteristics of low energy and good color purity, which comprehensively surpasses various fluorescent materials in the prior art, and at the same time achieves the effect of emitting yellow phosphorescent light and improving device performance; the divalent complex of the present invention is used as a luminescent material, and its CIE coordinates and luminous efficiency are more in line with the requirements of flat panel displays. At the same time, this series of yellow phosphorescent materials can be used as auxiliary light color materials for blue light to form a high-efficiency and high-stability white phosphorescent light source, and has great development potential in the fields of display and lighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a luminescence spectrum diagram of complex 6 in a specific embodiment of the present invention in solution and film;

[0028] Figure 2 is a luminescence spectrum diagram of the complex 15 in a specific embodiment of the present invention in a solution and a film;

[0029] Figure 3 is a luminescence spectrum diagram of the complex 81 in a specific embodiment of the present invention in a solution and a film;

[0030] Figure 4 is the UV-visible absorption spectrum of complex 6 in a specific embodiment of the present invention;

[0031] Figure 5 is a UV-visible absorption spectrum of complex 15 in a specific embodiment of the present invention;

[0032] Figure 6 is the complex 6 in the specific embodiment of the present invention 1 H NMR spectrum;

[0033] Figure 7 is the complex 15 in the specific embodiment of the present invention 1 H NMR spectrum;

[0034] Figure 8 is a purity characterization diagram of complex 15 in a specific embodiment of the present invention;

[0035] Fig. 9 is a mass spectrum of complex 15 in a specific embodiment of the present invention;

[0036] Fig.10 is a mass spectrum of complex 81 in a specific embodiment of the present invention;

[0037] Fig.11 is a cross-sectional view of an OLED device in a specific embodiment of the present invention;

[0038] Fig.12 is the luminescence spectrum of the yellow phosphorescent device using complexes 6, 15, and 81 in a specific embodiment of the present invention;

[0039] Fig.13 The CIE coordinate diagram of the luminescence spectrum of the yellow phosphorescent device using the complexes 6, 15, and 81 in the specific embodiment of the present invention is shown in FIG. Fig.14 is an external quantum efficiency diagram of a yellow phosphorescent device using complexes 6, 15, and 81 in a specific embodiment of the present invention; DETAILED DESCRIPTION

[0040] The present invention is further illustrated by examples below:

[0041] In the following specific embodiments of the present invention, complex 6, complex 15 and complex 81 are taken as examples to specifically illustrate the synthesis method, properties and performance of the divalent platinum complex provided by the present invention when used as a luminescent material.

[0042]

[0043] The various preparation methods of the compounds provided by the present invention are exemplary. These methods are used to illustrate various preparation methods, but are not intended to be limited to any specific method, and the temperature, catalyst, concentration, reactant composition and other process conditions may vary. This series of complexes can be synthesized by the route of the present invention, as follows:

[0044]

[0045] In addition, in the embodiments, the concentrations of the samples were recorded by a Varian liquid NMR spectrometer in a CDCl3 or DMSO-d6 solution. 1 HNMR (hydrogen nuclear magnetic resonance) and 13 C NMR spectra were recorded at 300, 400 or 500 MHz, and chemical shifts were based on residual protonated solvent. If CDCl3 was used as solvent, tetramethylsilane (δ = 0.00 ppm) was used as an internal reference. 1 H NMR (hydrogen nuclear magnetic resonance) spectrum; recorded using CDCl3 (δ = 77.00 ppm) as an internal reference 13 C NMR (carbon nuclear magnetic resonance) spectrum. If DMSO-d6 is used as solvent, residual H2O (δ=3.33 ppm) is used as an internal reference to record 1 H NMR (hydrogen nuclear magnetic resonance) spectrum; recorded using DMSO-d6 (δ = 39.52 ppm) as an internal reference 13 C NMR (carbon nuclear magnetic resonance) spectroscopy. The following abbreviations are used to explain 1 H NMR (hydrogen nuclear magnetic resonance) multiplicity: s = singlet, d = doublet, t = triplet, q = quadruplet, p = quintet, m = multitet, br = broad.

[0046] Example 1 Complex 6 and its preparation

[0047] Synthesis of 2'-chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine:

[0048]

[0049] 2',6'-dichloro-2,4'-bipyridine (1.37 g, 4.4 mmol), 3-nitrophenol (0.56 g, 4 mmol), 2,2,6,6-tetramethyl-3,5-heptanedione (590 mg, 3.2 mmol), cuprous bromide (58 mg, 0.4 mmol), cesium carbonate (3.26 g, 10 mmol) and N,N-dimethylformamide (20 mL) were added to a 75 mL sealed tube with a magnetic rotor. The resulting mixture was heated to 130 ° C and stirred for 36 hours after nitrogen bubbling for 10 minutes. After cooling to room temperature, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed with an appropriate amount of saturated sodium chloride aqueous solution, and dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the crude product was separated and purified by silica gel column chromatography. The eluent was petroleum ether: ethyl acetate = 25: 1 to obtain a white solid with a yield of 46%.

[0050] Synthesis of 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine:

[0051]

[0052] 2'-Chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine (107.9 mg, 0.33 mmol), 4,4,5,5-tetramethyl-2-(prop-1-en-2-yl)-1,3,2-dioxaborane (139 mg, 0.825 mmol), tetrakistriphenylphosphine palladium (12 mg, 0.01 mmol), potassium carbonate (69 mg, 0.5 mmol), ethylene glycol dimethyl ether (0.75 mL) and water (0.75 mL) were added to a 5 mL sealed tube with a magnetic rotor. The resulting mixture was heated to 100°C and stirred overnight after nitrogen bubbling for 10 minutes. The mixture was cooled to room temperature, quenched with water, extracted with ethyl acetate, and the organic phases were combined, washed with an appropriate amount of saturated sodium chloride aqueous solution, and dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the obtained crude product was separated and purified by silica gel column chromatography with petroleum ether:ethyl acetate = 25:1 as the eluent to obtain a white solid with a yield of 98%.

[0053] Synthesis of 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy))aniline:

[0054]

[0055] 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine (108 mg, 0.325 mmol), Pd / C (10 mg), methanol (8 mL) and tetrahydrofuran (8 mL) were added to a 50 mL round-bottom flask equipped with a magnetic rotor, and the resulting mixture was stirred at room temperature for 24 hours under a hydrogen atmosphere. After the reaction was completed, the reaction system was filtered and washed with a large amount of ethyl acetate. The filtrate obtained by filtration was distilled under reduced pressure to remove the solvent, and the crude product was separated and purified by silica gel column chromatography, with the eluent being petroleum ether: ethyl acetate = 25:1, to obtain a white solid with a yield of 78%.

[0056] Synthesis of pyridinediamine derivatives 1-4:

[0057]

[0058] To a sealed tube in a glove box was added the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline (305 mg, 1 mmol), 2-chloro-N-isopropyl-6-methylpyridin-3-amine (202 mg, 1.1 mmol), tris(dibenzylideneacetone)dipalladium (45.5 mg, 0.05 mmol), 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (31.1 mg, 0.5 mmol), sodium tert-butoxide (144 mg, 1.5 mmol) and toluene (4 mL). After bubbling the mixture for 15 minutes, the mixture was heated at 130°C for 20 hours. After cooling, ethyl acetate was added and the mixture was filtered. The aqueous phase was extracted with ethyl acetate and the organic phases were mixed, washed with brine and dried over anhydrous Na2SO4. The obtained solution was purified by silica gel chromatography using PE:EA=6:1 as the eluent, and the eluent was spin-dried to obtain the pyridinediamine derivative 1-4 (yellow viscous liquid, yield 90%).

[0059] Synthesis of carbene hexafluorophosphate 1-5:

[0060]

[0061] Add the intermediate pyridine diamine derivative (226 mg, 0.5 mmol), ammonium hexafluorophosphate (90 mg, 1.1 mmol) and triethyl orthoformate (1 mL) to a sealed tube. Heat at 120°C overnight. After cooling to room temperature, add ethyl acetate to precipitate a yellow precipitate, which is filtered to obtain carbene hexafluorophosphate (yellow solid, yield 60%).

[0062] Synthesis of complex 6:

[0063]

[0064] Add intermediate 1-5 (304 mg, 0.5 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 168 mg, 0.45 mmol), sodium acetate (43 mg, 0.53 mmol) and THF (1 mL) into a sealed tube. Heat at 120°C for 3 days. Cool to room temperature and spin dry. Use DCM: PE = 2: 1 as eluent and purify the obtained solution by silica gel chromatography to obtain the target product: complex 6 (yellow powder, yield 70%). NMR (400MHz, CDCl3) δ8.86(d,J=5.6Hz,1H),8.29(d,J=7.6Hz,1H),7.78-7.76(m,2H),7.69(d,J=8.4Hz,1H),7.21-7.13(m,2H),7.1 1-7.07(m,3H),5.29-5.23(m,1H),3.14-3.09(m,1H),2.71(s,3H),1.65(d,J=7.2Hz,6H),1.40(d,J=7.2Hz,6H).MS(ESI):657.5[M] + .The emission peak in dichloromethane (DCM) solution is 562nm, and the half-maximum width (FWHM) is 69nm. The emission peak in polymethyl methacrylate (PMMA) film is 561nm, and FWHM is 147nm.

[0065] Example 2 Complex 15 and its preparation

[0066] Synthesis of pyridinediamine derivative 2-1:

[0067]

[0068] To a sealed tube in a glove box was added the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline (305 mg, 1 mmol), 2-chloro-N-(2,6-diisopropylphenyl)-6-methylpyridin-3-amine (332 mg, 1.1 mmol), tris(dibenzylideneacetone)dipalladium (45.5 mg, 0.05 mmol), 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (31.1 mg, 0.5 mmol), sodium tert-butoxide (144 mg, 1.5 mmol) and toluene (4 mL). After bubbling the mixture for 15 minutes, the mixture was heated at 130°C for 20 hours. After cooling, ethyl acetate was added and the mixture was filtered. The aqueous phase was extracted with ethyl acetate and the organic phases were mixed, washed with brine and dried over anhydrous Na2SO4. The obtained solution was purified by silica gel chromatography using PE:EA=6:1 as the eluent, and the eluent was spin-dried to obtain the pyridinediamine derivative 2-1 (yellow viscous liquid, yield 90%).

[0069] Synthesis of carbene hexafluorophosphate 2-2:

[0070]

[0071] Add the intermediate pyridine diamine derivative (285 mg, 0.5 mmol), ammonium hexafluorophosphate (90 mg, 1.1 mmol) and triethyl orthoformate (1 mL) to a sealed tube. Heat at 120°C overnight. After cooling to room temperature, add ethyl acetate to precipitate a yellow precipitate, which is filtered to obtain carbene hexafluorophosphate 2-2 (yellow solid, yield 60%).

[0072] Synthesis of complex 15:

[0073]

[0074] Add intermediate 2-2 (364 mg, 0.5 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 168 mg, 0.45 mmol), sodium acetate (43 mg, 0.53 mmol) and THF (1 mL) into a sealed tube. Heat at 120°C for 3 days. Cool to room temperature and spin dry. Use DCM: PE = 2: 1 as eluent and purify the obtained solution by silica gel chromatography to obtain the target product: complex 15 (yellow powder, yield 70%). NMR (400MHz, CDCl3) δ8.84 (dd, J=7.2, 1.6Hz, 1H), 7.83 (d, J=8.0Hz, 1H), 7.76 (t, J=8.0 Hz,1H),7.72-7.68(m,1H),7.52(d,J=8.0Hz,2H),7.39-7.32(m,2H),7.18(s,1H),7.16- 7.10(m,2H),6.66(d,J=5.6,1H),6.58-6.55(m,1H),3.16-3.12(m,1H),2.78(s,3H),2. 70-2.63(m,2H),1.38(s,3H),1.36(s,3H),1.09(d,J=6.8Hz,6H),1.05(d,J=6.8Hz,6H). MS(ESI):776.7[M+1] + The emission peak in dichloromethane (DCM) solution is 549nm, and the half-maximum width (FWHM) is 59nm. The emission peak in polymethyl methacrylate (PMMA) film is 545nm, and FWHM is 35nm.

[0075] Example 3 Complex 81 and its preparation

[0076] Synthesis of 2'-(3-nitrophenoxy)-6'-phenyl-2,4'-bipyridine:

[0077]

[0078] 2'-Chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine (107.9 mg, 0.33 mmol), phenylboronic acid (100 mg, 0.825 mmol), tetrakistriphenylphosphine palladium (12 mg, 0.01 mmol), potassium carbonate (69 mg, 0.5 mmol), ethylene glycol dimethyl ether (0.75 mL) and water (0.75 mL) were added to a 5 mL sealed tube with a magnetic rotor. The resulting mixture was heated to 100°C and stirred overnight after nitrogen bubbling for 10 minutes. After cooling to room temperature, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed with an appropriate amount of saturated sodium chloride aqueous solution, and dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the crude product was separated and purified by silica gel column chromatography. The eluent was petroleum ether: ethyl acetate = 25: 1 to obtain a white solid with a yield of 98%.

[0079] Synthesis of 3-((6'-phenyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline:

[0080]

[0081] 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine (120 mg, 0.325 mmol), Pd / C (10 mg), methanol (8 mL) and tetrahydrofuran (8 mL) were added to a 50 mL round-bottom flask equipped with a magnetic rotor, and the resulting mixture was stirred at room temperature for 24 hours under a hydrogen atmosphere. After the reaction was completed, the reaction system was filtered and washed with a large amount of ethyl acetate. The filtrate obtained by filtration was distilled under reduced pressure to remove the solvent, and the crude product was separated and purified by silica gel column chromatography, with the eluent being petroleum ether: ethyl acetate = 25:1, to obtain a white solid with a yield of 78%.

[0082] Synthesis of pyridinediamine derivative 3-3:

[0083]

[0084] To a sealed tube in a glove box was added the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline (339 mg, 1 mmol), 2-chloro-N-isopropyl-6-methylpyridin-3-amine (202 mg, 1.1 mmol), tris(dibenzylideneacetone)dipalladium (45.5 mg, 0.05 mmol), 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (31.1 mg, 0.5 mmol), sodium tert-butoxide (144 mg, 1.5 mmol) and toluene (4 mL). After bubbling the mixture for 15 minutes, the mixture was heated at 130°C for 20 hours. After cooling, ethyl acetate was added and the mixture was filtered. The aqueous phase was extracted with ethyl acetate and the organic phases were mixed, washed with brine and dried over anhydrous Na2SO4. The obtained solution was purified by silica gel chromatography using PE:EA=6:1 as the eluent, and the eluent was spin-dried to obtain the pyridinediamine derivative 3-3 (yellow viscous liquid, yield 90%).

[0085] Synthesis of carbene hexafluorophosphate 3-4:

[0086]

[0087] Add the intermediate pyridine diamine derivative (243 mg, 0.5 mmol), ammonium hexafluorophosphate (90 mg, 1.1 mmol) and triethyl orthoformate (1 mL) to a sealed tube. Heat at 120°C overnight. After cooling to room temperature, add ethyl acetate to precipitate a yellow precipitate, which is filtered to obtain carbene hexafluorophosphate (yellow solid, yield 60%).

[0088] Synthesis of complex 81:

[0089]

[0090] Add intermediate 3-4 (322 mg, 0.5 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 168 mg, 0.45 mmol), sodium acetate (43 mg, 0.53 mmol) and THF (1 mL) into a sealed tube. Heat at 120°C for 3 days. Cool to room temperature and spin dry. Use DCM: PE = 2: 1 as eluent and purify the obtained solution by silica gel chromatography to obtain the target product: complex 81 (yellow powder, yield 70%). NMR (400MHz, CDCl3) δ8.91 (d, J = 5.2 Hz, 1H), 8.38 (d, J = 7.2, 1H), 8.15 (d, J = 1. 6Hz,1H),8.13-8.12(m,1H),7.87(d,J=8.0Hz,1H),7.82-7.78(m,1H),7.73-7 .71(m,1H),7.65(s,1H),7.52-7.47(m,3H),7.43-7.41(m,1H),7.23-7.18(m, 2H),7.11-7.09(m,1H),5.35-7.28(m,1H),2.71(s,3H),1.70(d,J=6.0Hz,6H).

[0091] MS(ESI):690.6[M] + The emission peak in dichloromethane (DCM) solution is 567nm, and the full width at half maximum (FWHM) is 61nm. The emission peak in polymethyl methacrylate (PMMA) film is 563nm, and FWHM is 70nm.

[0092] Example 4 Characterization of the Luminescence Properties of Complexes 6, 15 and 81

[0093] The above-mentioned complexes 6, 15 and 81 are yellow phosphorescent luminescent materials or phosphorescent luminescent materials, and the peak wavelength of the yellow phosphorescent light is in the range of 550-570nm.

[0094] Representative data of the color purity of the emitter can be obtained from the emission spectrum of a film prepared by using 5% doped complex material in polymethyl methacrylate (PMMA). Table 1 shows the emission spectrum data of each complex. In the following Table 1, λ is the peak wavelength, and CIE (x, y) is the chromaticity coordinate parameter according to the International Commission on Illumination standard. The peak wavelengths of complexes 6, 15, and 81 prepared in the embodiments of the present invention are between 545 and 570 nm, and their half-peak widths are all above 35 nm, indicating that the divalent platinum complex having the structure of general formula I is a yellow phosphorescent luminescent material.

[0095] Table 1 Emission spectrum data of complexes

[0096]

[0097] Attached Figure 1-3 The luminescence spectra of divalent platinum complexes 6, 15 and 81 in solution and film are shown in turn; under 400nm ultraviolet light excitation, the luminescence wavelengths of the three complexes in dichloromethane solution and polymethyl methacrylate (PMMA) are between 550-570nm, and the wavelengths of all complexes are in the yellow phosphorescence region. Figure 1 The effect of co-luminescence of molecular monomers and aggregated states was demonstrated, indicating that this series of divalent platinum complexes with 5-6-5 cyclic structure are good spectrally tunable yellow luminescent materials.

[0098] Attached Figure 4 , Figure 5 The UV-visible absorption spectra of the above-mentioned divalent platinum complexes 6 and 15 in dichloromethane solution are shown respectively. According to the absorption spectra, it can be seen that the absorption spectrum has very strong absorption in the range of 250-450nm. Among them, the absorption below 370nm can be attributed to the π-π centered on the ligand in the complex. * Transition. The absorption peak after 370nm can be attributed to the valence state transfer transition (MLCT) between the metal ion in the center of the complex and the ligand. The energy absorption of this type of molecule is very efficient and can be used as the preferred molecular structure of the doping material molecule. The wavelength below 280nm is the π-π transition of the benzene ring or pyridine ring under spin permission. * Transition, 280nm-370nm is the π-π transition of the carbazole ligand * Transition; the absorption above 370nm is derived from the d-π transition state from metal to ligand * Transition.

[0099] The band gap and related optical properties of the divalent platinum complexes 6, 15, and 81 provided by the embodiments of the present invention are characterized as follows: g ), the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) values ​​were measured by cyclic voltammetry (CV). The entire test process was carried out on a CHI600D electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) in a glove box (Lab2000, Etelux). A three-electrode system was formed with a Pt column as the working electrode, Ag / AgCl as the reference electrode, and a Pt wire as the auxiliary electrode. The medium used in the test process was a 0.1M tetrabutylammonium hexafluorophosphate (Bu4NPF6) dimethylformamide (DMF) solution, and the measured potentials were all based on the added ferrocene (Fc) as the internal standard. In the table below, λ is the peak wavelength of the divalent platinum complex dissolved in dichloromethane, FWHM is its half-peak width, and the triplet photon energy of the material (E T1 ) is calculated from the formula 1240 / λ 0→1 Calculated from (λ 0→1is the first vibration peak under 77K conditions), and its unit is electron volt (eV).

[0100] Table 2 Energy level data

[0101] Complex <![CDATA[E HOMO (eV)]]> <![CDATA[E LUMO (eV)]]> <![CDATA[E g (eV)]]> λ(nm) <![CDATA[E T1 (eV)]]> Complex 6 -5.22 -2.68 2.54 523 2.37 Complex 15 -5.56 -2.64 2.92 514 2.41 Complex 81 -5.12 -2.74 2.38 533 2.33

[0102] Attached Figure 6 , 7 The single molecules of complexes 6 and 15 are 1 H NMR spectrum shows that the complex can exist independently and stably, and is easy to separate, purify and characterize. From the NMR spectrum, in addition to the stable structural characterization of the divalent platinum complex, the divalent platinum complex does not show any signal of aggregation, indicating that in the solution state, this type of divalent platinum complex molecules exist in a single molecule isolated state.

[0103] Attached Figure 8 The ultra-high pressure liquid phase purity analysis diagram of the purified complex 15. The liquid phase purity is 99.1%, indicating that an ultra-high purity product can be obtained by the method provided in this specification, and the complex is practical for suitable process amplification.

[0104] Attached Fig. 9 This is the mass spectrometry characterization diagram of the molecule of complex 15. The mass spectrometry molecule shows that the molecular signal shows an M / C peak of 776.7, which is consistent with the molecular ion peak of compound 15, indicating that the structure of the complex is the designed structure.

[0105] Attached Fig.10 This is a mass spectrometry characterization diagram of the molecule of complex 81. The mass spectrometry molecule shows that the molecular signal shows an M / C peak of 690.6, which is consistent with the molecular ion peak of compound 81, indicating that the structure of the complex is the designed structure.

[0106] Example 5 Application of complexes 6, 15 and 81 in organic optoelectronic devices

[0107] The present invention provides an organic photoelectric device, which comprises a light-emitting layer. The divalent platinum complex is a light-emitting material, a host material or a guest material in the light-emitting layer of the organic photoelectric device.

[0108] Attached Fig.11A cross-sectional view of an OLED light emitting device 1000 is shown, the OLED device comprising a divalent platinum complex disclosed herein. The OLED device 1000 includes a substrate 1002, an anode layer 1004, a hole transport layer 1006, a light emitting layer 1008, an electron transport layer 1010, and a metal cathode layer 1012. The anode 1004 is generally a transparent material, such as indium tin oxide. The light emitting layer 1008 can be a light emitting material including one or more emitters and a host. Wherein EIL refers to an electron injection layer, which can be regarded as a part of the electron transport layer 1010. HIL is a hole injection layer, which can be regarded as a part of the hole transport layer 1006. CPL is a cathode capping layer.

[0109] The crucible containing OLED organic material and the crucible containing metal aluminum particles are placed on the positions of the organic evaporation source and the inorganic evaporation source in turn. The cavity is closed, and the initial vacuum and high vacuum steps are performed to make the vacuum degree of evaporation inside the OLED evaporation equipment reach 10E-7Torr. OLED evaporation film forming method: Open the OLED organic evaporation source, preheat the OLED organic material to 100°C, and the preheating time is 15 minutes to ensure that the water vapor in the OLED organic material is further removed. Then the organic material to be evaporated is quickly heated, and the baffle above the evaporation source is opened until the evaporation source of the material has organic material running out, and the crystal oscillator detector detects the evaporation rate, and then slowly heats up, the temperature rise is 1-5°C, until the evaporation rate is stable at 1A / second, open the baffle directly below the mask plate, and perform OLED film formation. When the computer observes that the organic film on the ITO substrate reaches the preset film thickness, close the mask plate baffle and the baffle directly above the evaporation source, and close the evaporation source heater of the organic material. The evaporation process of other organic materials and cathode metal materials is as described above. The packaging was performed by UV epoxy resin light curing packaging. The encapsulated samples were tested for IVL performance, and the IVL equipment was Mc Science M6100 for testing.

[0110] The complex 6, complex 15 and complex 81 disclosed in this specification are used as yellow phosphorescent doping materials in the light-emitting layer to prepare a yellow phosphorescent device. When the complex doping material is used in an OLED device, a yellow phosphorescent device is prepared by a steam distillation method. The structure of device 1 is (ITO, 95nm) / 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC, 30nm) / 9,9'-(1,3-phenyl)bis-9H-carbazole (mCP, 10nm) / mCP: complex (20:1, 20nm) / bis[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO ,5nm) / 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]bipyridine (TmPyPB,40nm) / lithium fluoride (LiF,1nm) / aluminum (Al,100nm), where ITO is the anode, TAPC is the hole transport material layer 1, mCP is the hole transport layer 2 and the main material of the light-emitting layer, DPEPO and TmPyPB are the electron transport layer, and Al is the cathode. The electroluminescence spectrum is as follows Fig.12 As shown:

[0111] The peak wavelength of the yellow phosphorescent device prepared by complex 15 is 560nm, and the half-peak width reaches 50nm. The peak wavelength of the yellow phosphorescent device prepared by complex 81 is 576nm, and the half-peak width reaches 72nm. The peak wavelength of the yellow phosphorescent device prepared by complex 6 is 573nm, and the half-peak width reaches 180nm. The EL light shows that the yellow phosphorescent material contained in the present luminescent device can achieve spectrum adjustment through molecular design, wherein the CIE coordinates of the electronic luminescence spectrum are as follows: Fig.13 As shown. The CIE coordinates of the electroluminescence spectrum of the device prepared by complex 15 are (0.43, 0.57); the CIE coordinates of the electroluminescence spectrum of the device prepared by complex 81 are (0.46, 0.53); the CIE coordinates of the electroluminescence spectrum of the device prepared by complex 6 are (0.50, 0.49), and the CIE of the above devices are all in the yellow light region. It fully shows that the design provided by the material of the present invention can meet the spectral tunability in the yellow light region.

[0112] In the structure of the OLED light-emitting device 1000, the light-emitting layer 1008 may include one or more divalent platinum complexes provided by the present invention, optionally with a host material and one or more doping materials. This specification provides a novel device structure as follows:

[0113] ITO / HIL(10nm) / HTL(70nm) / EML(20nm) / HBL(10nm) / ETL(40nm) / EIL(2nm) / Al,

[0114] Among them, HIL is the hole injection layer which can be HATCN; HTL is the hole transport layer which can be TAPC; NPD; PT301; EML is the light-emitting layer, which is the platinum complex in this article doped with the main material, the doping ratio can be 1% to 10%, and the main material can be mCP; 2,6mCPy, mCBP; HBL is the hole blocking layer which can be 2,6mCPy; ETL is the electron transport layer which can be TPBi, DPPS, BPyTP, etc.

[0115] Among them, HATCN is 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene; NPD is N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine; PT-301 is 4,4'-bis[N,N-di(biphenyl-4-yl)amino]-1,1'-biphenyl; 2,6mCPy is 2 ,6-Di(9H-carbazole-9-yl)pyridine; mCBP is 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl; TPBi is 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene; DPPS is diphenylbis[4-(pyridin-3-yl)phenyl]silane; BPyTP is 2,7-di(2,2'-bipyridin-5-yl)triphenylene

[0116] The efficiency of the device prepared by using the material of the present invention is as follows Fig.14 shown.

[0117] Depend on Fig.14 It can be seen that the devices prepared using the materials of the present invention have excellent photoelectric properties. The maximum EQE of the device prepared by complex 81 is 13.5%, the maximum EQE of the device prepared by complex 15 is 18%, and the maximum EQE of the device prepared by complex 6 is 11.8%. This shows that the yellow phosphorescent material provided by the present invention is suitable for preparing high-efficiency yellow phosphorescent devices.

[0118] Through the above device structure, yellow phosphorescent devices were prepared using three demonstration complexes, and the device results are shown in Table 3.

[0119] Table 3 Device luminescence performance

[0120]

[0121] Table 3 shows the luminescence performance data of the white phosphorescent light-emitting devices prepared by various complexes. Under the same conditions, the efficiency of the light-emitting device is consistent with the luminescence quantum efficiency of the platinum complex itself, and at 1000 cd·m -2 The light-emitting device spectrum is basically consistent with the light-emitting yellow phosphor material.

[0122] The present invention uses an exemplary embodiment to illustrate that the general structure I can be used as a yellow phosphorescent doped material to prepare a single doped yellow phosphorescent device and a double doped white phosphorescent device with a blue phosphorescent material, wherein each material is not limited to the exemplary structure; based on the application, the device structure can be a bottom-emitting device or a top-emitting device. The ETL layer 1010 and the HTL 1006 can also include one or more transport layer materials, and there can be another charge injection layer near the divalent platinum complex and the electrode. The materials of the injection layer may include an EIL (electron injection layer), a HIL (hole injection layer) and a CPL (cathode cover layer), which can be in the form of a single layer or dispersed in an electron or hole transport material. The host material can be any suitable host material known in the art. The luminescent color of the OLED is determined by the luminescent energy (optical energy gap) of the luminescent layer 1008 material, and the luminescent energy (optical energy gap) of the luminescent layer 1008 material can be tuned by tuning the electronic structure of the emitting divalent platinum complex and / or the host material as described above. The hole transport material in the HTL layer 1006 and the electron transport material in the ETL layer 1010 may include any suitable hole transporter known in the art. The divalent platinum complex provided by the embodiments of the present invention may exhibit phosphorescence. Phosphorescent OLEDs (i.e., OLEDs with phosphorescent emitters) generally have higher device efficiencies than other OLEDs such as fluorescent OLEDs.

[0123] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A divalent platinum complex, characterized in that The divalent platinum complex has a structure shown in Formula I: Among them, R a , R c and R d Each is independently a hydrogen atom, an isotope thereof, or an alkyl group having 1 to 14 carbon atoms; R b , R e are methyl, benzyl, diphenylmethyl, triphenylmethyl, which are each independently deuterated or non-deuterated; ethyl, 2-phenylethyl, 2,2-phenylethyl, 2,2,2-trifluoroethyl; propyl, isopropyl, 3,3,3-trifluoropropyl, 1,1,1,3,3,3-hexafluoro-2-propyl; n-butyl, isobutyl, hexafluoroisobutyl, tert-butyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl; phenyl, 2-methylphenyl, 2-isopropylphenyl, 2-ethylphenyl , 4-methylphenyl, 4-isopropylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 2,3-dimethylphenyl, 2,3-diethylphenyl, 2,3-diisopropylphenyl, 2,3-diisobutylphenyl, 2,3-dicyclohexylphenyl, 2,3-dicyclopropylphenyl, 2,3-dicyclobutylphenyl, 2,3-dicyclopentylphenyl, 2,4-dimethylphenyl, 2,4-diethylphenyl, 2,4-diisopropylphenyl, 2,4-diisobutylphenyl, 2,4-di Cyclohexylphenyl, 2,4-dicyclopropylphenyl, 2,4-dicyclobutylphenyl, 2,4-dicyclopentylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,6-diisobutylphenyl, 2,6-dicyclohexylphenyl, 2,6-dicyclopropylphenyl, 2,6-dicyclobutylphenyl, 2,6-dicyclopentylphenyl, 3,5-dimethylphenyl, 3,5-diethylphenyl, 3,5-diisopropylphenyl, 3,5-diisobutylphenyl phenyl, 3,5-dicyclohexylphenyl, 3,5-dicyclopropylphenyl, 3,5-dicyclobutylphenyl, 3,5-dicyclopentylphenyl, 2,3,5,6-tetramethylphenyl, 2,4,6-trimethylphenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 2,4,6-triisobutylphenyl, 2,4,6-tricyclohexylphenyl, 2,4,6-tricyclopropylphenyl, 2,4,6-tricyclobutylphenyl, 2,4,6-tricyclopentylphenyl.

2. The divalent platinum complex according to claim 1, characterized in that R a , R c and R d They can be independently selected from hydrogen atoms and deuterium atoms.

3. The divalent platinum complex according to claim 1, characterized in that The divalent platinum complex has a structure selected from one of the following complexes 1 to 90:

4. The divalent platinum complex according to claim 1, characterized in that The divalent platinum complex R a , R c A hydrogen atom.

5. The divalent platinum complex according to claim 1, characterized in that R a , R c and R d A hydrogen atom.

6. A method for preparing the divalent platinum complex according to any one of claims 1 to 5, comprising the following synthesis steps: Step 1: Pass is the basic unit for starting coupling; wherein, X is selected from Cl, Br, I, OTf; Step 2: Perform a two-step coupling reaction to obtain corresponding fragment coupling intermediates, wherein the two-step coupling reaction includes any one of Ullmann coupling and Buchwald-Hartwig coupling reaction; The third step: imidazole ring-closing reaction, specifically, under the action of a fluorine-containing anion salt, the coupled intermediate and triethyl orthoformate are condensed into a ring in one step to obtain a precursor of the final product ligand, wherein the fluorine-containing anion of the precursor includes a hexafluorophosphate anion; Step 4: Synthesis of divalent platinum complexes, by reacting the ligand precursor and the divalent platinum compound at above 80°C to directly obtain the divalent platinum complex, wherein the divalent platinum compound can be potassium tetrachloroplatinite, (1,5-cyclooctadiene) platinum dichloride, or platinum dichloride.

7. A method for preparing the complex 6 as claimed in claim 3, wherein the specific steps are as follows: Step 1: Synthesis of 2'-chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine: To a 75 mL sealed tube with a magnetic rotor, 1.37 g, 4.4 mmol of 2', 6'-dichloro-2,4'-bipyridine, 0.56 g, 4 mmol of 3-nitrophenol, 590 mg, 3.2 mmol of 2,2,6,6-tetramethyl-3,5-heptanedione, 58 mg, 0.4 mmol of cuprous bromide, 3.26 g, 10 mmol of cesium carbonate and 20 mL of N,N-dimethylformamide were added. The resulting mixture was bubbling with nitrogen for 10 minutes, heated to 130°C and stirred for 36 hours, cooled to room temperature, quenched with water, extracted with ethyl acetate, combined organic phases, washed with an appropriate amount of saturated sodium chloride aqueous solution, dried over anhydrous sodium sulfate, and distilled under reduced pressure to remove the solvent. The resulting crude product was separated and purified by silica gel column chromatography, the eluent being petroleum ether: ethyl acetate = 25: 1, to obtain a white solid with a yield of 46%; Step 2: Synthesis of 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine: To a 5 mL sealed tube with a magnetic rotor, 107.9 mg, 0.33 mmol of 2'-chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine, 139 mg, 0.825 mmol of 4,4,5,5-tetramethyl-2-(prop-1-en-2-yl)-1,3,2-dioxaborane, 12 mg, 0.01 mmol of tetrakistriphenylphosphine palladium, 69 mg, 0.5 mmol of potassium carbonate, 0.75 mL of ethylene glycol dimethyl ether and 0.75 mL of water were added. The resulting mixture was bubbling with nitrogen for 10 minutes and then heated to 100°C and stirred overnight. The mixture was cooled to room temperature and quenched with water. The reaction was extracted with ethyl acetate, the organic phases were combined, washed with an appropriate amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate, and the solvent was removed by distillation under reduced pressure. The resulting crude product was separated and purified by silica gel column chromatography. The eluent was petroleum ether: ethyl acetate = 25: 1 to obtain a white solid with a yield of 98%; Step 3: Synthesis of 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy))aniline: To a 50 mL round-bottom flask with a magnetic rotor, 108 mg, 0.325 mmol of 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine, 10 mg of Pd / C, 8 mL of methanol and 8 mL of tetrahydrofuran were added, and the resulting mixture was stirred at room temperature for 24 hours under a hydrogen atmosphere. After the reaction was completed, the reaction system was filtered and washed with a large amount of ethyl acetate. The filtrate obtained by filtration was distilled under reduced pressure to remove the solvent, and the resulting crude product was separated and purified by silica gel column chromatography, with the eluent being petroleum ether: ethyl acetate = 25:1, to obtain a white solid with a yield of 78%; Step 4: Synthesis of pyridinediamine derivatives 1-4: Into a sealed tube in the glove box were added 305 mg, 1 mmol of the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline, 202 mg, 1.1 mmol of 2-chloro-N-isopropyl-6-methylpyridin-3-amine, 45.5 mg, 0.05 mmol of tris(dibenzylideneacetone)dipalladium, 31.1 mg, 0.5 mmol of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), 144 mg, 1.5 mmol of tert-butoxide and 4 mL of toluene, after bubbling the mixture with nitrogen for 15 minutes, the mixture was heated at 130°C for 20 hours, and after cooling, ethyl acetate was added, and the mixture was filtered, the aqueous phase was extracted with ethyl acetate, and the organic phases were mixed, washed with brine, and dried with anhydrous Na2SO4. PE: EA = 6: 1 was used as an eluent, and the obtained solution was purified by silica gel chromatography, and the eluent was spin-dried to obtain pyridinediamine derivative 1-4 as a yellow viscous liquid with a yield of 90%; Step 5: Synthesis of carbene hexafluorophosphate 1-5: Add 226 mg, 0.5 mmol of the intermediate pyridine diamine derivative, 90 mg, 1.1 mmol of ammonium hexafluorophosphate and 1 mL of triethyl orthoformate to a sealed tube, heat at 120°C overnight, cool to room temperature, add ethyl acetate to precipitate a yellow precipitate, filter to obtain carbene hexafluorophosphate as a yellow solid, with a yield of 60%; Step 6: Synthesis of complex 6: 304 mg, 0.5 mm intermediate 1-5, 168 mg, 0.45 mmol dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 43 mg, 0.53 mmol sodium acetate and 1 mL THF were added to a sealed tube, heated at 120°C for 3 days, cooled to room temperature and then spin-dried, and the obtained solution was purified by silica gel chromatography using DCM:PE=2:1 as eluent to obtain the target product: complex 6 as a yellow powder with a yield of 70%.

8. A method for preparing the complex 15 as claimed in claim 3, wherein the specific steps are as follows: Step 1: Synthesis of pyridinediamine derivative 2-1: Into a sealed tube in the glove box were added 305 mg, 1 mmol of the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline, 332 mg, 1.1 mmol of 2-chloro-N-(2,6-diisopropylphenyl)-6-methylpyridin-3-amine, 45.5 mg, 0.05 mmol of tris(dibenzylideneacetone)dipalladium, 31.1 mg, 0.5 mmol of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), 144 mg, 1.5 mmol of sodium tert-butoxide and 4 mL of toluene, after bubbling the mixture with nitrogen for 15 minutes, the mixture was heated at 130°C for 20 hours, and after cooling, ethyl acetate was added, and the mixture was filtered, the aqueous phase was extracted with ethyl acetate, and the organic phases were mixed, washed with brine, and dried with anhydrous Na2SO4. PE: EA = 6: 1 was used as an eluent, and the obtained solution was purified by silica gel chromatography, and the eluent was spin-dried to obtain the pyridinediamine derivative 2-1 as a yellow viscous liquid with a yield of 90%; Step 2: Synthesis of carbene hexafluorophosphate 2-2: Add 285 mg, 0.5 mmol of the intermediate pyridine diamine derivative, 90 mg, 1.1 mmol of ammonium hexafluorophosphate and 1 mL of triethyl orthoformate to a sealed tube, heat at 120°C overnight, cool to room temperature, add ethyl acetate to precipitate a yellow precipitate, filter to obtain carbene hexafluorophosphate 2-2 as a yellow solid, with a yield of 60%; Step 3: Synthesis of complex 15: 364 mg, 0.5 mmol of intermediate 2-2, 168 mg, 0.45 mmol of dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 43 mg, 0.53 mmol of sodium acetate and 1 mL of THF were added to a sealed tube, heated at 120°C for 3 days, cooled to room temperature and then spin-dried, and the obtained solution was purified by silica gel chromatography using DCM:PE=2:1 as eluent to obtain the target product: complex 15 as a yellow powder with a yield of 70%.

9. A method for preparing the complex 81 as claimed in claim 3, wherein the specific steps are as follows: Step 1: Synthesis of 2'-(3-nitrophenoxy)-6'-phenyl-2,4'-bipyridine: To a 5 mL sealed tube with a magnetic rotor, 107.9 mg, 0.33 mmol of 2'-chloro-6'-(3-nitrophenoxy)-2,4'-bipyridine, 100 mg, 0.825 mmol of phenylboric acid, 12 mg, 0.01 mmol of tetrakistriphenylphosphine palladium, 69 mg, 0.5 mmol of potassium carbonate, 0.75 mL of ethylene glycol dimethyl ether and 0.75 mL of water were added. The resulting mixture was heated to 100°C and stirred overnight after nitrogen bubbling for 10 minutes, cooled to room temperature, and water was added to quench the reaction. The mixture was extracted with ethyl acetate, the organic phases were combined, washed with an appropriate amount of saturated sodium chloride aqueous solution, and dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the resulting crude product was separated and purified by silica gel column chromatography. The eluent was petroleum ether: ethyl acetate = 25: 1 to obtain a white solid with a yield of 98%; Step 2: Synthesis of 3-((6'-phenyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline: 120 mg, 0.325 mmol of 2'-(3-nitrophenoxy)-6'-(prop-1-en-2-yl)-2,4'-bipyridine, 10 mg of Pd / C, 8 mL of methanol and 8 mL of tetrahydrofuran were added to a 50 mL round-bottom flask with a magnetic rotor. The obtained mixture was stirred at room temperature for 24 hours under a hydrogen atmosphere. After the reaction was completed, the reaction system was filtered and washed with a large amount of ethyl acetate. The filtrate obtained by filtration was distilled under reduced pressure to remove the solvent. The obtained crude product was separated and purified by silica gel column chromatography, and the eluent was petroleum ether: ethyl acetate = 25: 1 to obtain a white solid with a yield of 78%; Step 3: Synthesis of pyridinediamine derivative 3-3: Into a sealed tube in the glove box were added 339 mg, 1 mmol of the intermediate 3-((6'-isopropyl-[2,4'-bipyridyl]-2'-yl)oxy)aniline, 202 mg, 1.1 mmol of 2-chloro-N-isopropyl-6-methylpyridin-3-amine, 45.5 mg, 0.05 mmol of tris(dibenzylideneacetone)dipalladium, 31.1 mg, 0.5 mmol of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), 144 mg, 1.5 mmol of tert-butoxide and 4 mL of toluene, after bubbling the mixture with nitrogen for 15 minutes, the mixture was heated at 130°C for 20 hours, and after cooling, ethyl acetate was added, and the mixture was filtered, the aqueous phase was extracted with ethyl acetate, and the organic phases were mixed, washed with brine, and dried with anhydrous Na2SO4. PE: EA = 6: 1 was used as an eluent, and the obtained solution was purified by silica gel chromatography, and the eluent was spin-dried to obtain pyridinediamine derivative 3-3 as a yellow viscous liquid with a yield of 90%; Step 4: Synthesis of carbene hexafluorophosphate 3-4: Add 243 mg, 0.5 mmol of the intermediate pyridine diamine derivative, 90 mg, 1.1 mmol of ammonium hexafluorophosphate and 1 mL of triethyl orthoformate to a sealed tube, heat at 120°C overnight, cool to room temperature, add ethyl acetate to precipitate a yellow precipitate, filter to obtain carbene hexafluorophosphate as a yellow solid, with a yield of 60%; Step 5: Synthesis of complex 81: 322 mg, 0.5 mmol of intermediate 3-4, 168 mg, 0.45 mmol of dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 43 mg, 0.53 mmol of sodium acetate and 1 mL of THF were added to a sealed tube, heated at 120°C for 3 days, cooled to room temperature and then spin-dried. The obtained solution was purified by silica gel chromatography using DCM:PE=2:1 as eluent to obtain the target product: complex 81 as a yellow powder with a yield of 70%.

10. Use of the divalent platinum complex according to any one of claims 1 to 5 in electroluminescent materials or photoluminescent materials.

11. Use of the divalent platinum complex according to any one of claims 1 to 5 as a phosphorescent material in an organic optoelectronic device.

12. Use of the divalent platinum complex according to any one of claims 1 to 5 as a yellow phosphorescent material in an organic optoelectronic device.

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