Divalent platinum complex, preparation method and application thereof, and organic photoelectric device

Abstract

The invention relates to the technical field of organic photoelectric material luminescence, and discloses a divalent platinum complex, a preparation method and application thereof and an organic photoelectric device, the divalent platinum complex has a structure as shown in formula (I): R1 is alkyl with at least two carbons; r2-R15 are the same or different and are independently selected from one or more of a hydrogen atom, a hydrogen isotope atom, a fluorine atom and a polyatomic substituent; the polyatomic substituent group comprises a substituted or unsubstituted alkyl group and / or a substituted or unsubstituted aryl group; the light-emitting wavelengths of the bivalent platinum complex in a dichloromethane solution and PMMA (polymethyl methacrylate) are both 500-540nm, and an OLED (organic light-emitting diode) device prepared from a luminous body can meet the standard of pure green light application;

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials luminescence technology, specifically to a divalent platinum complex, its preparation method and application, and organic optoelectronic devices. Background Technology

[0002] Currently, the development and application of materials that can directly convert electricity into light occupy an increasingly important position in the field of light emission. These materials often possess very high conversion efficiency and characteristic spectral light emission properties. Especially in materials for display-related optical or electroluminescent devices, their development is rapidly driving the advancement of today's widespread electronic information field and has become a hot topic in technological research and development. Organic transition metal complexes possess strong spin-orbit coupling effects, thus they can be used as phosphorescent materials in organic light-emitting diodes (OLEDs). This technology is widely used in solid-state light emission fields such as flat panel displays and lamps. Related products have advantages such as conformability and low energy consumption, representing molecular-level semiconductor technology with excellent development prospects.

[0003] In the visual application of light emission, red, green, and blue (RGB) are generally considered the three primary colors, and various colors perceived by the eye can be obtained by combining these three primary colors. Green light is one of the three primary colors and is also the most visually sensitive color, making it an indispensable part of display and lighting applications. Currently, green phosphorescent materials, mainly based on organometallic complex structures, have achieved great success in lighting and flexible display applications. Based on the diversity of organic molecules in organic light-emitting materials, it is proposed to regulate the luminescence properties by adjusting the structure of organic molecules to meet the needs of various organic displays and achieve optimal display effects, such as longer device lifespan, wider color gamut, and higher light extraction efficiency (lower power consumption).

[0004] Therefore, the development of high-quality green phosphorescent materials has practical application value in organic solid-state luminescence applications. Furthermore, developing novel luminescent materials based on application requirements is beneficial for the diversification of luminescent agents in organic luminescence applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing green phosphorescent materials in light-emitting applications, such as low efficiency, narrow spectrum, and instability. This invention provides a divalent platinum complex, its preparation method, its applications, and an organic optoelectronic device. The divalent platinum complex emits light in dichloromethane solution at wavelengths between 500-540 nm and in polymethyl methacrylate (PMMA), making it a highly efficient green phosphorescent material with good stability and long lifespan. OLED devices prepared using this material can meet the standards for pure green light applications.

[0006] To achieve the above objectives, a first aspect of the present invention provides a divalent platinum complex having the structure shown in formula (I):

[0007]

[0008] In equation (I):

[0009] R1 is an alkyl group having at least two carbon atoms;

[0010] R2-R 15 The same or different, each independently selected from one or more of hydrogen atoms, hydrogen isotopes, fluorine atoms and polyatomic substituents; the polyatomic substituents include substituted or unsubstituted alkyl groups and / or substituted or unsubstituted aryl groups.

[0011] A second aspect of this invention provides a method for preparing divalent platinum complexes, characterized in that the preparation method comprises the following synthetic steps:

[0012] (1) Under a protective gas, compound a shown in formula (a) is reacted with compound b shown in formula (b) to obtain pyridine compound c with substituents shown in formula (c);

[0013] (2) Under a protective gas, the pyridine compound c with substituent shown in formula (c) is reacted with the phenol compound d with substituent shown in formula (d) to obtain compound e shown in formula (e).

[0014] (3) In the presence of a divalent platinum source and N,N-dimethylformamide (DMF), compound e of formula (e) was subjected to a cyclometalation reaction to obtain the divalent platinum complex of formula (I);

[0015]

[0016] The definitions of the groups in formulas (I), (a), (b), (c), (d), and (e) are the same as those described above; X in formulas (a), (b), and (c) may be the same or different, and may be F, Br, I, Cl, or OTf (trifluoromethanesulfonyl).

[0017] A third aspect of the present invention provides a divalent platinum complex prepared by the preparation method described above.

[0018] The fourth aspect of this invention provides an application of the aforementioned divalent platinum complex in organic optoelectronic devices.

[0019] The fifth aspect of this invention provides an application of the aforementioned divalent platinum complex in green phosphorescent organic optoelectronic devices.

[0020] The sixth aspect of the present invention provides an organic optoelectronic device, wherein the organic optoelectronic device includes a substrate, an anode layer, a hole transport layer, a light-emitting layer, an electron transport layer and a metal cathode layer, and at least one of the light-emitting layer, the electron transport layer and the hole transport layer contains the aforementioned divalent platinum complex.

[0021] Through the above technical solution, the divalent platinum complex is a green phosphorescent divalent platinum complex. The green phosphorescent divalent platinum complex provided by this invention exhibits an emission wavelength between 500-540 nm in dichloromethane solution, preferably between 524-535 nm, and an emission wavelength between 500-540 nm in PMMA, preferably between 527-532 nm. It demonstrates good stability, an efficiency greater than 99%, and an emission half-width of less than 63 nm, preferably less than 50 nm, with a minimum of 33 nm. OLED devices fabricated using this emitting material can achieve CIE coordinates (x, y) of (0.35, 0.63), meeting the standards for pure green light applications. Attached Figure Description

[0022] Figure 1 This is the emission spectrum of complex 1 prepared in Example 1 of the present invention in solution and thin film;

[0023] Figure 2 This is the emission spectrum of complex 2 prepared in Example 2 of the present invention in solution and thin film;

[0024] Figure 3 This is the emission spectrum of complex 3 prepared in Example 3 of the present invention in solution and thin film;

[0025] Figure 4 It is the complex 1 prepared in Example 1 of this invention. 1 H NMR spectrum;

[0026] Figure 5 It is the complex 2 prepared in Example 2 of this invention. 1 H NMR spectrum;

[0027] Figure 6 It is the complex 3 prepared in Example 3 of this invention. 1 H NMR spectrum;

[0028] Figure 7 This is the mass spectrum of complex 1 prepared in Example 1 of the present invention;

[0029] Figure 8 This is the mass spectrum of complex 2 prepared in Example 2 of the present invention;

[0030] Figure 9 This is the mass spectrum of complex 3 prepared in Example 3 of the present invention;

[0031] Figure 10 The diagram shows the structure of an OLED light-emitting device;

[0032] Figure 11 This is the device emission spectrum of complex 1 prepared in Example 1 of the present invention;

[0033] Figure 12 This is the device emission spectrum of complex 2 prepared in Example 2 of the present invention;

[0034] Figure 13 This is the device emission spectrum of complex 3 prepared in Example 3 of the present invention;

[0035] Figure 14 This is a schematic diagram of the EQE-current density curve of complex 1 prepared in Example 1 of the present invention;

[0036] Figure 15 This is a schematic diagram of the EQE-current density curve of complex 2 prepared in Example 2 of the present invention;

[0037] Figure 16 This is a schematic diagram of the EQE-current density curve of the complex 3 prepared in Example 3 of the present invention. Detailed Implementation

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] A first aspect of the present invention provides a divalent platinum complex, wherein the divalent platinum complex has the structure shown in formula (I):

[0040]

[0041] In equation (I):

[0042] R1 is an alkyl group having at least two carbon atoms;

[0043] R2-R 15 The same or different, each independently selected from one or more of hydrogen atoms, hydrogen isotopes, fluorine atoms and polyatomic substituents; the polyatomic substituents include substituted or unsubstituted alkyl groups and / or substituted or unsubstituted aryl groups.

[0044] The inventors of this invention discovered that the human eye can generally perceive green light in the 500-560nm wavelength range. However, there are higher chromaticity standards for the green light required for displays. Currently, two standards are widely accepted: one is the CIE chromaticity coordinate system for green light (0.21, 0.71), and the other is the BT2020 standard, with CIE coordinates of (0.170, 0.797). The latter has higher chromaticity requirements than the former, thus placing higher demands on the monochromaticity of the light source. Calculations and analysis show that monochromatic light with a wavelength in the 520-535nm range better meets the chromaticity requirements of the BT2020 standard. In other words, the synthesized complex material needs to have a peak emission value in the 520-535nm range. The narrower its spectrum, the better it meets the chromaticity requirements of the BT2020 standard, and the better the monochromaticity of the material, allowing for better utilization in displays.

[0045] Furthermore, the parent core of this invention contains alkyl-substituted benzimidazole structural units with two or more C atoms attached to the N atom. The large alkyl substituents increase the out-of-plane structure of the complex molecule, shielding the dipole interaction between the imidazole moiety and the environment, thus providing a novel green, high-efficiency, narrow-spectrum phosphorescent material. Therefore, the resulting phosphorescent material exhibits better stability. In addition, the complex structural unit has high rigidity, enabling the acquisition of a larger π-conjugated system and a narrower spectrum, thereby improving luminescence uniformity, enhancing emission color, and improving device performance. It also makes the triplet excited state more stable, improving molecular structure and luminescence stability. In the embodiments of this invention, the disclosed divalent platinum complex molecule containing a neutral tetradentate ligand coordinated with a large alkyl-substituted benzimidazole structure can emit green light as a phosphorescent material, exhibiting good stability, high efficiency, and a narrow luminescence range, making it perfectly suitable as an organic green light emitter in OLED-related products. Furthermore, the compounds provided in the embodiments of this invention are easy to prepare and sublimate for purification, soluble in common organic solvents, and suitable for both vapor deposition and solution processing methods in device fabrication. These materials exhibit excellent color purity in their luminescent properties, which will change the situation in the flat panel display field where there is a lack of stable and efficient narrow-band green phosphorescent doped materials. At the same time, they can achieve the effect of emitting green light and improving device performance. The stable complex luminescent materials provided by the embodiments of the present invention have CIE coordinates and luminous efficiency that better meet the needs of flat panel displays.

[0046] According to the present invention, in the divalent platinum complex, the polyatomic substituent comprises one or more of unsubstituted alkyl, aryl-substituted alkyl, fluorine-substituted alkyl, unsubstituted aryl, and alkyl-substituted aryl; preferably, the polyatomic substituent comprises C1-C1. 20 Alkyl, C5-C 30 Aryl groups.

[0047] According to the present invention, in the divalent platinum complex, R1 is an alkyl group having at least two carbons, and the alkyl group includes one or more of aryl-substituted alkyl groups, silyl groups, substituted or unsubstituted cycloalkyl groups; preferably, each R1 is independently selected from deuterated substituents - CDR. a R b and / or -CD2R a , where R a and R b Each is independently selected from C2-C 12 Alkyl, C5-C 30 Aromatic groups, C1-C 12 The alkoxy group or the above-mentioned substituent containing an isotopic atom; preferably, the alkyl group includes one or more of unsubstituted straight-chain alkyl, substituted straight-chain alkyl, unsubstituted cycloalkyl and substituted cycloalkyl; preferably, the aromatic group includes one or more of unsubstituted aryl, substituted aryl, aryloxy, arylamine and heteroaryl.

[0048] According to the present invention, preferably, R1 is independently selected from deuterated substituents - CDR. a R b and / or -CD2R a , where R a and R b Each is independently selected from C2-C 10 alkyl.

[0049] According to the present invention, preferably, R1 is independently selected from deuterated substituents - CDR. a R b and / or -CD2R a , where R a and R b Each is independently selected from unsubstituted straight-chain alkyl and / or aryl-substituted alkyl groups.

[0050] According to the present invention, in the divalent platinum complex, R1 is independently selected from benzyl, diphenylmethyl, triphenylmethyl, ethyl, 2-phenylethyl, 2,2-phenylethyl, 2,2,2-trifluoroethyl, n-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, and cycloheptyl.

[0051] According to the present invention, in the divalent platinum complex, R2-R 15 Each is independently selected from deuterated substituents -CDH2, -CD2H, -CD3, -CDR a R b -CD2R a One or more of them, wherein Ra and R b Each is independently selected from C1-C 12 Alkyl, C5-C 30 Aromatic groups, C1-C 12 One or more of the above-mentioned substituents containing alkoxy or isotopic atoms; preferably, the alkyl group includes one or more of unsubstituted straight-chain alkyl, substituted straight-chain alkyl, unsubstituted cycloalkyl, and substituted cycloalkyl; preferably, the aromatic group includes one or more of unsubstituted aryl, substituted aryl, aryloxy, arylamine, and heteroaryl; more preferably, R a and R b Each is independently selected from C1-C 10 Alkyl and / or C5-C 24 Aromatic group; more preferably, the alkyl group includes one or more of aryl-substituted alkyl, silyl and haloalkyl; more preferably, the aromatic group includes alkyl-substituted aryl and / or aryl-substituted aryl.

[0052] According to the present invention, in the divalent platinum complex, preferably, R2-R 15 Each is independently selected from unsubstituted deuterated aryl and / or substituted deuterated aryl-Ar-dn, wherein Ar is selected from one or more of aryl, aryl-substituted aryl and alkyl-substituted aryl; and the deuterated hydrogen dn is selected from one deuterated, multiple deuterated, or all hydrogens are deuterated.

[0053] According to the present invention, the isotopic atom is a deuterium atom or a deuterium-substituted atom.

[0054] According to the present invention, the alkyl group is selected from one or more of methyl, ethyl, propyl, butyl, pentyl and hexyl.

[0055] According to the present invention, the aryl group is selected from one or more of phenyl, naphthyl and biphenyl.

[0056] According to the present invention, the cycloalkyl group is selected from one or more of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl.

[0057] According to the present invention, in the divalent platinum complex, R2-R 15Independently selected from 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, 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-dicyclohexylphenyl, 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, 3,5- One or more of the following: 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, and 2,4,6-tricyclopentylphenyl.

[0058] According to the present invention, the divalent platinum complex is selected from at least one of the complexes shown in complexes 1 to 30:

[0059]

[0060]

[0061]

[0062] According to the present invention, the emission wavelength of the divalent platinum complex in dichloromethane solution is between 500-540 nm, preferably between 524-535 nm, and the emission wavelength in PMMA is between 500-540 nm, preferably between 527-532 nm, with a emission half-width of less than 63 nm, preferably less than 50 nm.

[0063] A second aspect of this invention provides a method for preparing divalent platinum complexes, characterized in that the preparation method comprises the following synthetic steps:

[0064] (1) Under a protective gas, compound a shown in formula (a) is reacted with compound b shown in formula (b) to obtain pyridine compound c with substituents shown in formula (c);

[0065] (2) Under a protective gas, the pyridine compound c with substituent shown in formula (c) is reacted with the phenol compound d with substituent shown in formula (d) to obtain compound e shown in formula (e).

[0066] (3) In the presence of a divalent platinum source and DMF, compound e shown in formula (e) is subjected to a cyclometalation reaction to obtain the divalent platinum complex shown in formula (I);

[0067]

[0068] The definitions of the groups in formulas (I), (a), (b), (c), (d), and (e) are the same as those described above; X in formulas (a), (b), and (c) may be the same or different, and may be F, Br, I, Cl, or OTf, respectively.

[0069] According to the present invention, in (1), compound a (1-50 mmol) of formula (a) and compound b (1-50 mmol) of formula (b) are reacted in the presence of tetrakis(triphenylphosphine)palladium, sodium carbonate, toluene, ethylene glycol-dimethyl ether, and water to obtain pyridine compound c with substituents as shown in formula (c); wherein, relative to 20 mL of water, the amount of tetrakis(triphenylphosphine)palladium is 0.5-1 mmol, the amount of sodium carbonate is 1-2 mmol, the amount of toluene is 10-15 mL, and the amount of ethylene glycol-dimethyl ether is 15-20 mL. Furthermore, in a glove box, the mixtures are bubbled for 15-20 minutes and then heated at 120-130°C for 24-30 hours. After cooling, ethyl acetate is added, and the mixture is filtered. The aqueous phase is extracted with ethyl acetate, and the organic phases are mixed, washed with brine, and dried with anhydrous sodium sulfate. The solution was purified by silica gel chromatography using petroleum ether (PE): ethyl acetate (EA) = (1-50): 1 as the eluent. The eluent was then evaporated to dryness to obtain the pyridine compound c with substituents shown in formula (c).

[0070] According to the present invention, in step (2), firstly, a phenol compound d with substituents as shown in formula (d) is prepared. Specifically, in step (2), the preparation of the phenol compound d with substituents includes any one of the following two methods:

[0071] The first method:

[0072] (I-2-1) Under a protective atmosphere, the substituted benzo[d]imidazole compound f shown in formula (f) is reacted with compound R1-X to obtain compound g shown in formula (g);

[0073]

[0074] In (I-2-1), the substituted benzo[d]imidazole compound f of formula (f) is reacted with compound R1-X (preferably 2-iodopropane) in the presence of potassium carbonate and dimethyl sulfoxide, wherein the amount of the substituted benzo[d]imidazole compound f of formula (f) is 10-15 mmol, the amount of compound R1-X is 10-15 mmol, and the amount of potassium carbonate is 12-15 mmol, relative to 50 mL of dimethyl sulfoxide. Furthermore, the above materials are mixed and bubbled in a glove box for 15-20 minutes, and then heated at 50-70°C for 12-13 hours. After cooling, ethyl acetate is added, and the mixture is filtered. The aqueous phase is extracted with ethyl acetate, and the organic phases are mixed, washed with brine, and dried with anhydrous sodium sulfate. The obtained solution is purified by silica gel chromatography using PE:EA = (1-50):1 as the eluent, and the eluent is evaporated to dryness to obtain compound g of formula (g).

[0075] (I-2-2) Under a protective gas, compound g, represented by formula (g), is reacted with compound h, represented by formula (h), to obtain compound i, represented by formula (i);

[0076]

[0077] In (I-2-2), compound g (g) and compound h (h) are reacted in the presence of DPPF palladium dichloride, triphenylphosphine, silver carbonate, and water; wherein, relative to 50 mL of water, the amount of compound g (g) is 10-15 mmol, the amount of compound h (h) is 10-15 mmol, the amount of DPPF palladium dichloride is 0.5-1 mmol, the amount of triphenylphosphine is 1-1.5 mmol, and the amount of silver carbonate is 0.5-1 mmol. Furthermore, the above materials are mixed and bubbled in a glove box for 15-20 minutes, and then heated at 100-120°C for 24-28 hours. After cooling, ethyl acetate is added, and the mixture is filtered. The aqueous phase is extracted with ethyl acetate, and the organic phases are mixed, washed with brine, and dried with anhydrous sodium sulfate. Using PE∶EA=(5-40)∶1 as the eluent, the obtained solution was purified by silica gel chromatography. The eluent was then evaporated to dryness to obtain compound i as shown in formula i.

[0078] (I-2-3) Under a protective gas, compound i, as shown in formula (i), is reacted with halide HX to obtain compound d, as shown in formula (d);

[0079] In (I-2-3), the amount of compound i, as shown in formula (i), is 3-5 mmol relative to 50 mL of halide HX; wherein, after heating at 110-120 °C for 6-48 h, cooling to room temperature, sodium bicarbonate is added to neutralize to pH 7, ethyl acetate is added, and the mixture is then filtered. The aqueous phase is extracted with ethyl acetate, and the organic phases are mixed, washed with brine, and dried with anhydrous sodium sulfate. The obtained solution is purified by silica gel chromatography using PE:EA = (5-40):1 as the eluent, and the eluent is evaporated to dryness to obtain compound d, as shown in formula (d).

[0080] The second method:

[0081] (II-2-1) Under a protective atmosphere, the substituent-containing benzene nitryl compound j shown in formula (j) is reacted with the R1-NH2 compound to obtain compound k shown in formula (k);

[0082]

[0083] In (II-2-1), the substituted benzyl nitrate compound j (1-50 mmol) of formula (j) is reacted with the R1-NH2 compound (1-50 mmol) in the presence of tris(dibenzylacetone)dipalladium, BINAP, sodium tert-butoxide, and toluene; wherein the amount of tris(dibenzylacetone)dipalladium is 0.5-1 mmol relative to 50 mL of toluene, the amount of BINAP is 1-1.5 mmol, and the amount of sodium tert-butoxide is 15-20 mmol. Furthermore, the above materials are mixed in a sealed tube, bubbled under nitrogen for 10-15 minutes, heated to 110-120°C, and stirred for 24-30 hours. After cooling to room temperature, water and ethyl acetate are added for extraction, the organic phase is washed with a suitable amount of saturated sodium chloride aqueous solution, and dried with anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath, and the crude product was purified by silica gel column chromatography with petroleum ether:ethyl acetate = (10-100):1 as the eluent. After purification, compound k, represented by formula (k), was obtained.

[0084] (II-2-2) Under a protective gas, compound k, represented by formula (k), is reduced to obtain compound m, represented by formula (m);

[0085] In (II-2-2), compound k, represented by formula (k), was reduced in the presence of iron powder, ammonium chloride, ethanol, and water. The amounts of compound k, represented by formula (k), were 16-20 mmol relative to 35 mL of water; the amounts of iron powder were 80-85 mmol; the amounts of ammonium chloride were 64-70 mmol; and the amounts of ethanol were 70-80 mL. In a 250 mL sealed tube, the above materials were mixed, bubbled under nitrogen for 10-15 minutes, heated to 95-100 °C, and stirred for 12-15 hours. After cooling to room temperature, water and ethyl acetate were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried with anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:ethyl acetate = (1-50):1 as the eluent. The purified product was compound m, represented by formula (m).

[0086] (II-2-3) Under a protective gas, compound m, represented by formula (m), is reacted with compound n, represented by formula (n), to obtain compound d, represented by formula (d);

[0087]

[0088] In (II-2-3), compound m of formula (m) and compound n of formula (n) are mixed and reacted with ethanol; wherein, relative to 30 mL of ethanol, the amount of compound m of formula (m) is 16-18 mmol, and the amount of compound n of formula (n) is 19-20 mmol. Additionally, in a 150 mL sealed tube, the above materials are mixed, bubbled under nitrogen for 10-15 minutes, heated to 95-100 °C, and stirred for 48-50 hours. After cooling to room temperature, water and ethyl acetate are added for extraction, the organic phase is washed with a suitable amount of saturated sodium chloride aqueous solution, and dried with anhydrous sodium sulfate. The solvent is removed by rotary evaporation in a water bath, and the crude product is purified by silica gel column chromatography using petroleum ether:ethyl acetate = (1-50):1 as the eluent, followed by slurrying with petroleum ether:dichloromethane = (1-50):1, and purification yields a white solid product.

[0089] Next, the substituted pyridine compound c shown in formula (c) and the substituted phenol compound d shown in formula (d) are reacted in the presence of cuprous iodide, BPPO, potassium phosphate and DMF to obtain compound e shown in formula (e); wherein, relative to 5 mL of DMF, the amount of the substituted pyridine compound c shown in formula (c) is 0.1-5 mmol, the amount of the substituted phenol compound d shown in formula (d) is 0.1-5 mmol, the amount of cuprous iodide is 0.05-1 mmol, the amount of BPPO is 0.05-1 mmol, and the amount of potassium phosphate is 2-5 mmol.

[0090] Alternatively, the substituted pyridine compound c of formula (c) is reacted with the substituted phenol compound d of formula (d) in the presence of cuprous bromide, N,N-dimethylglycine, cesium carbonate, and 1,4-dioxane to obtain compound e of formula (e); wherein, relative to 20-25 mL of 1,4-dioxane, the amount of the substituted pyridine compound c of formula (c) is 7-12 mmol, the amount of the substituted phenol compound d of formula (d) is 4-5 mmol, the amount of cuprous bromide is 0.4-0.5 mmol, the amount of N,N-dimethylglycine is 0.2-0.5 mmol, and the amount of cesium carbonate is 8-10 mmol.

[0091] In addition, after mixing and bubbling the above materials in a sealed tube for 10-15 minutes, the mixture is heated at 120-130°C for 24-48 hours. After cooling, water and / or ethyl acetate are added, and the mixture is then filtered. The aqueous phase is extracted with ethyl acetate, and the organic phases are mixed, washed with brine, and dried with anhydrous sodium sulfate. The obtained solution is purified by silica gel chromatography using PE:EA = (1-50):1 as the eluent. The eluent is then evaporated to dryness to obtain compound e as shown in formula (e).

[0092] According to the present invention, in step (3), compound e of formula (e) is subjected to a cyclometalation reaction in the presence of a divalent platinum source and DMF (N,N-dimethylformamide) to obtain the divalent platinum complex of formula (I); wherein, relative to 56-100 mL of DMF, the amount of compound e of formula (e) is 1-2 mmol, and the amount of divalent platinum source is 1.1-1.5 mmol. Furthermore, the above materials are mixed in a 48-500 mL sealed tube, bubbled with nitrogen for 10-15 minutes, heated at 30-40°C for 24-30 hours, and then heated at 120-130°C for 48-50 hours. After cooling to room temperature, the solution is evaporated to dryness, and purified by silica gel chromatography using PE:DCM = (1-20):1 as the eluent to obtain the complex.

[0093] A third aspect of the present invention provides a divalent platinum complex prepared by the preparation method described above.

[0094] The fourth aspect of this invention provides an application of the aforementioned divalent platinum complex in organic optoelectronic devices.

[0095] The fifth aspect of this invention provides an application of the aforementioned divalent platinum complex in green phosphorescent organic optoelectronic devices.

[0096] The sixth aspect of the present invention provides an organic optoelectronic device, wherein the organic optoelectronic device includes a substrate, an anode layer, a hole transport layer, a light-emitting layer, an electron transport layer and a metal cathode layer, and at least one of the light-emitting layer, the electron transport layer and the hole transport layer contains the aforementioned divalent platinum complex.

[0097] According to the present invention, the light-emitting layer contains the aforementioned divalent platinum complex.

[0098] According to the present invention, the divalent platinum complex is a luminescent material, a host material, or a guest material in the luminescent layer.

[0099] The present invention will be described in detail below through embodiments.

[0100] In the following examples and comparative examples:

[0101] Nuclear magnetic resonance (NMR) spectroscopy analysis: ¹H NMR (hydrogen NMR) and ¹³C NMR (carbon NMR) were measured using a Varian liquid NMR spectrometer in CDCl₃ or DMSO-d₆ solutions. ¹H NMR spectra were recorded at 300, 400, or 500 MHz, and ¹³C NMR spectra were recorded at 125 MHz. Chemical shifts were referenced to the residual pure solvent. The recorded ¹H NMR spectra used residual water (δ = 3.33 ppm in DMSO-d₆) as an internal reference; ¹³C NMR spectra were recorded using DMSO-d₆ (δ = 39.52 ppm) as an internal reference.

[0102] Mass spectrometry analysis: Electrospray ionization liquid chromatography-mass spectrometry (ESI-MS) or soft ionization high-resolution time-of-flight tandem mass spectrometry (MALDI-TOF-MS) are used for mass spectrometry testing.

[0103] Material sublimation and purification: The carbene platinum complex, the final product synthesized in the experiment, must be sublimated and purified to achieve a purity of ≥99.9% required for device fabrication and deposition.

[0104] High performance liquid chromatography analysis: The purity of intermediates and platinum complex final products during the synthesis process was tested using a methanol / water system or a tetrahydrofuran / acetonitrile system as the mobile phase.

[0105] Thermogravimetric analysis (TGA): The test was conducted in an inert gas atmosphere, with the temperature controlled by a program at a heating rate of 10℃ / min and an operating scan range of 30-550℃. By analyzing the thermogravimetric curves, information related to mass, such as the composition of the sample and its possible intermediate products, the thermal decomposition temperature of the sample (the temperature at which 5% mass loss occurs), the thermal decomposition process, and the products generated, was obtained.

[0106] Differential scanning calorimetry (DSC): The test is performed in an inert gas atmosphere, using a sample mass of 3-5 mg. The temperature is programmed and conducted at a temperature that does not deplete the sample. The thermodynamic and kinetic parameters of platinum complexes, such as glass transition temperature, crystallization temperature, and melting temperature, can be measured by plotting the rate of heat absorption or release (dH / dt, in millijoules per second) on the ordinate and temperature T or time t on the abscissa.

[0107] Cyclic voltammetry testing and energy level calculation: A three-electrode system was used for the tests, with a platinum column as the working electrode, a platinum wire as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Under a protective atmosphere, 0.1M tetra(n-butylammonium) / hexafluorophosphate was used as the auxiliary electrolyte, anhydrous N,N-dimethylformamide or anhydrous dichloromethane as the solvent, and ferrocene as the internal reference. The scan rate was 50-100 mV / s. The true frontier orbital energy levels (HOMO and LUMO) of the platinum complex were calculated based on formulas 5-1 and 5-2 and the redox peaks relative to the redox positions of ferrocene in the same system. To avoid errors from different systems and measurement cycles, the redox positions of ferrocene were only selected from the results of the same test procedure.

[0108] HOMO=-[Eox-EFc / Fc+ox+4.8]eV 5-1

[0109] LUMO=-[Ered-EFc / Fc+red+4.8]eV 5-2

[0110] Wherein: Eox and Ered are the oxidation peak initiation potential and reduction peak initiation potential of the sample, respectively; EFc / Fc+ox and EFc / Fc+red are the oxidation peak initiation potential and reduction peak initiation potential of ferrocene, respectively; and the vacuum energy level of ferrocene is 4.8 eV.

[0111] UV-Vis absorption spectroscopy: Measured at room temperature in a dichloromethane solution and in the prepared thin film. Select cuvettes of the same specifications. The test scanning range is 200-800 nm, and the scanning interval is 1 nm.

[0112] Steady-state spectroscopy tests included emission spectra in dichloromethane solution at room temperature, emission spectra in polymethyl methacrylate (PMMA) films doped with a 5% doping concentration at room temperature, and emission and excitation spectra in 2-methyltetrahydrofuran at a low temperature of 77 K. The films were prepared by spin-coating under nitrogen protection in a glove box and used immediately before testing to prevent quenching by atmospheric oxygen and subsequent errors. Additionally, an integrating sphere was constructed in a nitrogen-protected dark chamber to test the luminescence quantum yield (PLQY) in platinum complex solutions and the 5% doped film.

[0113] Transient spectroscopy and phosphorescence lifetime testing: Time-resolved spectroscopy and temperature-dependent emission spectroscopy were performed in dichloromethane solution at room temperature to test the emission lifetime in solution and polymethyl methacrylate (PMMA) film. All tests were conducted under a protective atmosphere or high vacuum.

[0114] Luminescence decay test: A 5% doped polymethyl methacrylate (PMMA) film was prepared, and the film of the platinum complex was irradiated with 370V ultraviolet light. The photostability of the platinum complex was determined by the decay curve of luminescence intensity and irradiation time.

[0115] X-ray crystal diffraction testing: Single crystals are prepared using solution evaporation and liquid-phase diffusion methods. X-ray crystal diffraction testing of the single crystals provides accurate information on molecular structure, including the packing state of platinum complex molecules, bond lengths, bond angles, and absolute configuration.

[0116] Testing of the luminescent properties of electroluminescent materials: CIE uses chromaticity coordinate parameters according to the International Commission on Illumination (ICI) standards.

[0117] The proton NMR spectra of the complexes were measured using a JEOL instrument, model JNM-ECZ400S / L1, purchased from Japan Electronics Corporation.

[0118] The purity and mass spectrometry of the complexes were tested using an ACQUITY UPLCH-class instrument purchased from WATERS Corporation.

[0119] The emission peak, lifetime, and efficiency of the complex solution or thin film were measured using the Fluorolog-3 transient-steady-state full-function fluorescence spectroscopy integrated testing platform purchased from Horiba, model FLS-1000.

[0120] The energy levels of the coordination compounds were measured using an electrochemical workstation (model CHI600D) purchased from Shanghai Chenhua Instrument Co., Ltd.

[0121] The present invention will be described in detail below through examples, including the synthesis of complexes 1, 2, 3, 19, and 21.

[0122] Example 1

[0123] This embodiment illustrates the preparation of complex 1.

[0124] (1) Synthesis of 2-(3-bromophenyl)-pyridine:

[0125]

[0126] 2-Bromo-pyridine (1.58 g, 10 mmol), (3-bromophenyl)boronic acid (3.0 g, 15 mmol), tetrakis(triphenylphosphine)palladium (577 mg, 0.5 mmol), sodium carbonate (105 mg, 1 mmol), toluene (10 mL), ethylene glycol dimethyl ether (15 mL), and water (20 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 120 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 30:1 as the eluent. The eluent was evaporated to dryness to give a yellow oily product in 52% yield.

[0127] (2) Synthesis of 1-isopropyl-1H-benzo[d]imidazole:

[0128]

[0129] 1H-benzo[d]imidazole (1.18 g, 10 mmol), 2-iodopropane (1.69 g, 10 mmol), potassium carbonate (1.06 g, 12 mmol), and dimethyl sulfoxide (50 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 50 °C for 12 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 7:1 as the eluent. The eluent was evaporated to dryness to give a pale yellow oily product in 65% yield.

[0130] (3) Synthesis of 1-isopropyl-2-(3-methoxyphenyl)-1H-benzo[d]imidazole:

[0131]

[0132] 1-Isopropyl-1H-benzo[d]imidazole (1.6 g, 10 mmol), 1-iodo-3-methoxybenzene (3.5 g, 15 mmol), DPPF palladium dichloride (365 mg, 0.5 mmol), triphenylphosphine (263 mg, 1 mmol), silver carbonate (138 mg, 0.5 mmol), and water (50 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 100 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 20:1 as the eluent. The eluent was evaporated to dryness to give a yellow oily product in 65% yield.

[0133] (4) Synthesis of 3-(1-isopropyl-1-benzo[d]imidazol-2-yl)phenol:

[0134]

[0135] 1-Isopropyl-2-(3-methoxyphenyl)-1H-benzo[d]imidazole (800 mg, 3 mmol) and hydrogen bromide (50 mL) were added to a sealed tube. The mixture was heated overnight at 110 °C, cooled to room temperature, and neutralized to pH 7 with sodium bicarbonate. 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 20:1 as the eluent. The eluent was evaporated to dryness to give a pale brown oily product in 50% yield.

[0136] (5) Synthesis of 1-isopropyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzo[d]imidazole:

[0137]

[0138] 3-(1-Isopropyl-1-benzo[d]imidazol-2-yl)phenol (252 mg, 1 mmol), 2-(3-bromophenyl)pyridine (351 mg, 1.5 mmol), cuprous iodide (10 mg, 0.05 mmol), BPPO (10 mg, 0.05 mmol), potassium phosphate (425 mg, 2 mmol), and DMF (5 mL) were added to a sealed tube. After bubbling the mixture for 15 minutes, it was heated at 120 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 15:1 as the eluent. The eluent was evaporated to dryness to give a dark brown oily product in 60% yield.

[0139] (6) Synthesis of complex 1:

[0140]

[0141] 1-Isopropyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzo[d]imidazole (405 mg, 1 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 223 mg, 1.1 mmol), and N,N-dimethylformamide (56 mL) were added sequentially to a 48 mL sealed tube equipped with a magnetic rotor. The mixture was heated at 30 °C for 24 hours and then at 120 °C for 48 hours. After cooling to room temperature, the mixture was evaporated to dryness. The resulting solution was purified by silica gel chromatography using DCM:PE = 4:1 as the eluent to give complex 1, a bright yellow powder, in 30% yield.

[0142] 1 H NMR (400MHz, CDCl3) δ9.40 (dd, J=5.5, 0.6Hz, 1H), 9.40 (dd, J=5.5, 0.6Hz, 1H), 9.40(dd,J=5.5,0.6Hz,2H),8.02(d,J=8.0Hz,1H),7.91(ddd,J=11.8,9.7,4.6H z,2H),7.73(d,J=8.1Hz,1H),7.51(ddd,J=10.8,6.9,1.7Hz,2H),7.39(ddd,J= 8.2,7.3,1.2Hz,1H),7.35-7.28(m,1H),1.85(d,J=7.0Hz,6H),1.54(d,J=7.1Hz 2H), 1.24(s, 1H).

[0143] Example 2

[0144] This embodiment illustrates the preparation of complex 2.

[0145] (1) The synthesis of 2-(3-bromophenyl)-pyridine is the same as in Example 1.

[0146] (2) Synthesis of 1-isopropyl-5,6-dimethyl-1H-benzo[d]imidazole:

[0147]

[0148] Add 5,6-dimethyl-1H-benzo[d]imidazole (1.46 g, 10 mmol), 2-iodopropane (3.5 g, 15 mmol), potassium carbonate (1.06 g, 12 mmol), and dimethyl sulfoxide (50 mL) to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, heat the mixture at 70 °C for 12 hours. After cooling, add ethyl acetate and filter the mixture. Extract the aqueous phase with ethyl acetate, and mix the organic phases, wash with brine, and dry with anhydrous sodium sulfate. Use PE:EA = 7:10 as the eluent, and purify the obtained solution by silica gel chromatography. Rotate the eluent to dryness to give a pale yellow oily product in 55% yield.

[0149] (3) Synthesis of 1-isopropyl-2-(3-methoxyphenyl)-5,6-dimethyl-1H-benzo[d]imidazole:

[0150]

[0151] 1-Isopropyl-5,6-dimethyl-1H-benzo[d]imidazole (1.88 g, 10 mmol), 1-iodo-3-methoxybenzene (1.69 g, 10 mmol), DPPF palladium dichloride (365 mg, 0.5 mmol), triphenylphosphine (263 mg, 1 mmol), silver carbonate (138 mg, 0.5 mmol), and water (50 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 100 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 25:1 as the eluent. The eluent was evaporated to dryness to give a brown oily product in 60% yield.

[0152] (4) Synthesis of 1-isopropyl-2-(3-methoxyphenyl)-5,6-dimethyl-1H-benzimidazole:

[0153]

[0154] 1-Isopropyl-2-(3-methoxyphenyl)-5,6-dimethyl-1H-benzo[d]imidazole (882 mg, 3 mmol) and hydrogen bromide (50 mL) were added to a sealed tube. The mixture was heated overnight at 110 °C, cooled to room temperature, and neutralized to pH 7 with sodium bicarbonate. 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 25:1 as the eluent. The eluent was evaporated to dryness to give a pale brown oily product in 55% yield.

[0155] (5) Synthesis of 1-isopropyl-5,6-dimethyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzimidazole:

[0156]

[0157] 3-(1-Isopropyl-5,6-dimethyl-1H-benzo[d]imidazolyl)phenol (280 mg, 1 mmol), 2-(3-bromophenyl)pyridine (351 mg, 1.5 mmol), cuprous iodide (10 mg, 0.05 mmol), BPPO (10 mg, 0.05 mmol), potassium phosphate (425 mg, 2 mmol), and DMF (5 mL) were added to a sealed tube. After bubbling the mixture for 15 minutes, it was heated at 120 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 25:1 as the eluent. The eluent was evaporated to dryness to give a dark brown oily product in 40% yield.

[0158] (6) Synthesis of complex 2:

[0159]

[0160] 1-Isopropyl-5,6-dimethyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzimidazole (433 mg, 1 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 223 mg, 1.1 mmol), and N,N-dimethylformamide (56 mL) were added sequentially to a 48 mL sealed tube equipped with a magnetic rotor. The mixture was bubbled under nitrogen for 10 minutes, heated at 30 °C for 24 hours, and then heated at 120 °C for 48 hours. After cooling to room temperature, the mixture was evaporated to dryness. The obtained solution was purified by silica gel chromatography using DCM:PE = 3:1 as the eluent to give complex 2, a bright yellow powder product, in 30% yield.

[0161] 1 H NMR (400MHz, CDCl3) δ9.45 (d, J=5.5Hz, 1H), 8.01-7.76 (m, 3H), 7.53-7.46 (m, 3H), 7.30 (ddd, J=8.4, 5. 0, 2.1Hz, 2H), 5.68 (dd, J = 13.9, 7.0Hz, 1H), 2.45 (d, J = 7.1Hz, 6H), 1.83 (d, J = 7.0Hz, 6H), 1.55 (s, 3H).

[0162] Example 3

[0163] This embodiment is intended to illustrate the preparation of complex 3.

[0164] (1) Synthesis of 2-(3-bromophenyl)-4-(tert-butyl)pyridine:

[0165]

[0166] 2-Bromo-4-(tert-butyl)pyridine (2.13 g, 10 mmol), (3-bromophenyl)boronic acid (3.0 g, 15 mmol), tetrakis(triphenylphosphine)palladium (577 mg, 0.5 mmol), sodium carbonate (105 mg, 1 mmol), toluene (10 mL), ethylene glycol dimethyl ether (15 mL), and water (20 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 120 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 30:1 as the eluent. The eluent was evaporated to dryness to give a yellow oily product in 50% yield.

[0167] (2) Synthesis of 1-isopropyl-1H-benzo[d]imidazole:

[0168]

[0169] 1H-benzo[d]imidazole (1.18 g, 10 mmol), 2-iodopropane (1.69 g, 10 mmol), potassium carbonate (1.06 g, 12 mmol), and dimethyl sulfoxide (50 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 50 °C for 12 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 7:1 as the eluent. The eluent was evaporated to dryness to give a pale yellow oily product in 65% yield.

[0170] (3) Synthesis of 1-isopropyl-2-(3-methoxyphenyl)-1H-benzo[d]imidazole:

[0171]

[0172] 1-Isopropyl-1H-benzo[d]imidazole (1.6 g, 10 mmol), 1-iodo-3-methoxybenzene (3.5 g, 15 mmol), DPPF palladium dichloride (365 mg, 0.5 mmol), triphenylphosphine (263 mg, 1 mmol), silver carbonate (138 mg, 0.5 mmol), and water (50 mL) were added to a sealed tube in a glove box. After bubbling the mixture for 15 minutes, it was heated at 100 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 20:1 as the eluent. The eluent was evaporated to dryness to give a yellow oily product in 65% yield.

[0173] (4) Synthesis of 3-(1-isopropyl-1-benzo[d]imidazol-2-yl)phenol:

[0174]

[0175] Add 1-isopropyl-2-(3-methoxyphenyl)-1H-benzimidazole (800 mg, 3 mmol) and hydrogen bromide (50 mL) to a sealed tube. Heat overnight at 110 °C, cool to room temperature, neutralize to pH 7 with sodium bicarbonate, add ethyl acetate, and filter the mixture. Extract the aqueous phase with ethyl acetate, mix the organic phases, wash with brine, and dry with anhydrous sodium sulfate. Use PE:EA = 20:1 as the eluent, purify the obtained solution by silica gel chromatography, evaporate the eluent to dryness, and give a light brown oily product with a yield of 50%. (5) Synthesis of 2-(3-(3'-(tert-butyl)-[1,1'-biphenyl]-3-oxy)phenyl)-1-isopropyl-1H-benzimidazole:

[0176]

[0177] 2-(3-bromophenyl)-4-(tert-butyl)pyridine (252 mg, 1 mmol), 3-(1-isopropyl-1H-benzimidazol-2-yl)phenol (345 mg, 1.5 mmol), cuprous iodide (10 mg, 0.05 mmol), BPPO (10 mg, 0.05 mmol), potassium phosphate (425 mg, 2 mmol), and DMF (5 mL) were added to a sealed tube. After bubbling the mixture for 15 minutes, it was heated at 120 °C for 24 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 sodium sulfate. The obtained solution was purified by silica gel chromatography using PE:EA = 35:1 as the eluent. The eluent was evaporated to dryness to give a dark brown oily product in 50% yield.

[0178] (6) Synthesis of complex 3:

[0179]

[0180] 2-(3-(3'-(tert-butyl)-[1,1'-biphenyl]-3-oxy)phenyl)-1-isopropyl-1H-benzimidazole (460 mg, 1 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl2, 223 mg, 1.1 mmol), and N,N-dimethylformamide (56 mL) were added sequentially to a 48 mL sealed tube equipped with a magnetic rotor. The mixture was bubbled under nitrogen for 10 minutes, heated at 30 °C for 24 hours, and then at 120 °C for 48 hours. After cooling to room temperature, the mixture was evaporated to dryness. The obtained solution was purified by silica gel chromatography using DCM:PE = 3:1 as the eluent to give complex 3, a bright yellow powder product, in 20% yield.

[0181] 1 H NMR(400MHz, CDCl3)δ8.11-8.06(m,1H),7.78-7.69(m,4H),7.67-7.56(m,4H), 7.54-7.43(m,6H),7.41-7.34(m,5H),5.35(t,J=4.6Hz,1H),1.89-1.84(m,9H).

[0182] Example 4

[0183] This embodiment illustrates the preparation of complex 19.

[0184] (1) The synthesis of 2-(3-bromophenyl)-pyridine is the same as in Example 1.

[0185] (2) Synthesis of 2,6-diisopropyl-N-(2-nitrophenyl)aniline:

[0186]

[0187] To a 250 mL sealed tube, 1-bromo-2-nitrobenzene (2.02 g, 10 mmol), 2,6-diisopropylaniline (2.65 g, 15 mmol), tris(dibenzylacetone)dipalladium (457.9 mg, 0.5 mmol), BINAP (622 mg, 1 mmol), sodium tert-butoxide (1.44 g, 15 mmol), and toluene (50 mL) were added sequentially. The mixture was bubbled under nitrogen for 10 minutes and heated to 110 °C with stirring for 24 hours. After cooling to room temperature, water and ethyl acetate were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:ethyl acetate = 80:1 as the eluent. The purified product was a yellow solid with a yield of 43.3%. 1H NMR(400MHz, DMSO-d6)δ9.31(s,1H),8.12(dd,J=8.6,1.6Hz,1H),7.45-7.36(m,2H),7.31(d,J=7.3Hz,2H),6. 77-6.68(m,1H),6.26(dd,J=8.7,1.2Hz,1H),3.02-2.91(m,2H),1.14(d,J=6.8Hz,6H),1.03(d,J=6.9Hz,6H).

[0188] (3) Synthesis of N1-(2,6-diisopropylphenyl)phenyl-1,2-diamine:

[0189]

[0190] 2,6-Diisopropyl-N-(2-nitrophenyl)aniline (4.76 g, 16 mmol), iron powder (4.5 g, 80 mmol), ammonium chloride (3.42 g, 64 mmol), ethanol (70 mL), and water (35 mL) were added sequentially to a 250 mL sealed tube. The mixture was bubbled under nitrogen for 10 minutes and heated to 95 °C with stirring for 12 hours. After cooling to room temperature, water and ethyl acetate were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:ethyl acetate = 20:1 as the eluent. The purified product was a brown oily product with a yield of 85.2%. 1H NMR (400MHz, DMSO-d6) δ7.68(s,1H),7.18(d,J=4.1Hz,4H),6.76(d,J=1.4Hz,1H),6.63(d,J=1.1Hz,1H),6. 23(s,1H),6.15(d,J=2.2Hz,2H),6.01(dd,J=8.1,1.1Hz,2H),1.11(d,J=6.7Hz,6H),1.09(d,J=6.8Hz,6H).

[0191] (4) Synthesis of 3-(1-(2,6-diisopropylphenyl)-1H-benzo[d]imidazolyl)phenol:

[0192]

[0193] N1-(2,6-diisopropylphenyl)benzene-1,2-diamine (4.47 g, 16 mmol), 3-hydroxybenzaldehyde (2.41 g, 19 mmol), and ethanol (30 mL) were added sequentially to a 150 mL sealed tube. The mixture was bubbled under nitrogen for 10 minutes and heated to 95 °C with stirring for 48 hours. After cooling to room temperature, water and ethyl acetate were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:ethyl acetate = 15:1 as the eluent, followed by slurrying with petroleum ether:dichloromethane = 10:1. The purified product was a white solid with a yield of 76.3%. 1H NMR(400MHz, DMSO-d6)δ9.65(s,1H),7.79(d,J=7.8Hz,1H),7.61(t,J=7.8Hz,1H),7.45(d,J=7.8Hz,2H),7.33-7.1 8(m,3H),7.07(t,J=8.0Hz,1H),6.88-6.74(m,3H),2.17-2.08(m,2H),0.88(d,J=6.8Hz,6H),0.89(d,J=6.9Hz,6H).

[0194] (5) Synthesis of 1-(2,6-diisopropylphenyl)-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzimidazole:

[0195]

[0196] Add 3-(1-(2,6-diisopropylphenyl)-1H-benzimidazol-2-yl)phenol (1.48 g, 4 mmol), 2-(3-bromophenyl)pyridine (2.8 g, 12 mmol), cuprous bromide (57.2 mg, 0.4 mmol), N,N-dimethylglycine (20.6 mg, 0.2 mmol), cesium carbonate (650 mg, 8 mmol), and 1,4-dioxane (20 mL) to a 150 mL sealing tube. Bubbling under nitrogen for 10 minutes, heating to 120 °C, and stirring for 48 hours. After cooling to room temperature, extract with water and ethyl acetate, wash the organic phase with a suitable amount of saturated sodium chloride aqueous solution, and dry with anhydrous sodium sulfate. Remove the solvent by rotary evaporation in a water bath, and purify the crude product by silica gel column chromatography using petroleum ether:ethyl acetate = 25:1 as the eluent. The purified product is a pale yellow oil with a yield of 47.1%. 1H NMR (400MHz, DMSO-d6) δ8.68-8.62(m,1H),7.98(d,J=8.0Hz,1H),7.78(d,J=7.9Hz,1H),7.62-7.54(m,2H),7.50-7.34(m,4H),7.32-7.15( m,5H),6.96-6.89(m,2H),6.83(d,J=7.9Hz,1H),5.76(s,1H),2.10-2.01(m,2H),0.85(d,J=6.8Hz,6H),0.71(d,J=6.9Hz,6H),0.03(s,1H).

[0197] (6) Synthesis of complex 19:

[0198]

[0199] 1-(2,6-diisopropylphenyl)-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzimidazole (0.5 g, 1 mmol), platinum dichloride (288 mg, 1.1 mmol), and N,N-dimethylformamide (100 mL) were added to a 500 mL sealed tube. The mixture was bubbled under nitrogen for 10 minutes, heated to 30 °C and stirred for 24 hours, then heated to 120 °C and stirred for 48 hours. After cooling to room temperature, water and dichloromethane were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:dichloromethane = 2:1 as the eluent. The purified product was a yellow solid complex 19, with a yield of 15.8%. 1H NMR(400MHz, CDCl3) δ9.64(d,J=5.4Hz,1H),8.13(d,J=8.2Hz,1H),8.03-7.91 (m,2H),7.66(t,J=7.8Hz,1H),7.58-7.36(m,5H),7.17(ddd,J=25.4,8.0,1.0H z,2H),7.01(d,J=8.0Hz,1H),6.87(t,J=7.8Hz,1H),6.30(dd,J=7.6,0.8Hz,1H ), 2.40 (d, J = 6.9Hz, 2H), 1.56 (d, J = 6.9Hz, 2H), 0.97 (dd, J = 14.1, 6.8Hz, 12H).

[0200] Example 5

[0201] This embodiment is intended to illustrate the preparation of complex 21.

[0202] (1) The synthesis of 2-(3-bromophenyl)-4-(tert-butyl)pyridine is the same as in Example 3.

[0203] (2) The synthesis of 3-(1-(2,6-diisopropylphenyl)-1H-benzo[d]imidazolyl)phenol is the same as in Example 4.

[0204] (3) Synthesis of 2-(3-(3-(4-tert-butylpyridin-2-yl)phenoxy)phenyl)-1-(2,6-diisopropylphenyl)-1H-benzimidazole:

[0205]

[0206] Add 3-(1-(2,6-diisopropylphenyl)-1H-benzo[d]imidazol)phenol (1.85 g, 5 mmol), 2-(3-bromophenyl)-4-(tert-butyl)pyridine (2.17 g, 7.5 mmol), cuprous bromide (71.5 mg, 0.5 mmol), N,N-dimethylglycine (25.8 mg, 0.25 mmol), cesium carbonate (3.25 g, 10 mmol), and 1,4-dioxane (25 mL) to a 75 mL sealed tube. Bubbling under nitrogen for 10 minutes, heating to 120 °C, and stirring for 48 hours. After cooling to room temperature, extract with water and ethyl acetate, wash the organic phase with a suitable amount of saturated sodium chloride aqueous solution, and dry with anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath, and the crude product was purified by silica gel column chromatography using petroleum ether:ethyl acetate = 30:1 as the eluent. The purified product was a pale yellow oil with a yield of 55.7%. 1H NMR(400MHz,DMSO-d6)δ8.52(d,J=5.5Hz,1H),8.20(s,1H),7.89-7.85(m,1H),7.7 6(d,J=8.2Hz,1H),7.62(dd,J=4.6,3.3Hz,3H),7.48-7.43(m,2H),7.31-7.24(m,4 H),7.20(dd,J=6.3,3.7Hz,2H),7.17(d,J=2.4Hz,2H),7.12(d,J=7.8Hz,2H),6.81 -6.75(m,2H),0.87(d,J=6.9Hz,6H),0.75(d,J=6.9Hz,6H),0.65(d,J=6.9Hz,9H).

[0207] (4) Synthesis of complex 21:

[0208]

[0209] 2-(3-(3-(4-tert-butylpyridin-2-yl)phenoxy)phenyl)-1-(2,6-diisopropylphenyl)-1H-benzimidazole (0.58 g, 1 mmol), platinum dichloride (288 mg, 1.1 mmol), and N,N-dimethylformamide (100 mL) were added to a 500 mL sealed tube. The mixture was bubbled under nitrogen for 10 minutes, heated to 30 °C and stirred for 24 hours, then heated to 120 °C and stirred for 48 hours. After cooling to room temperature, water and dichloromethane were added for extraction. The organic phase was washed with a suitable amount of saturated sodium chloride aqueous solution and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation in a water bath. The crude product was purified by silica gel column chromatography using petroleum ether:dichloromethane = 5:1 as the eluent. The purified product was a yellow solid complex 21, with a yield of 12.1%. 1H NMR (400MHz, CDCl3) δ8.15(d,J=8.2Hz,1H),7.96(d,J=2.0Hz,1H),7.66(t,J=7.8Hz,1H),7.59-7.49(m,1H ),7.45(dd,J=6.0,2.1Hz,3H),7.42-7.34(m,1H),7.33-7.27(m,1H),7.25(d,J=7.7Hz,1H)7.19(dd,J=8.0 ,1.0Hz,1H),7.12(dd,J=8.1,0.8Hz,1H),7.00(d,J=7.9Hz,1H),6.86(t,J=7.8Hz,1H),6.29(dd,J=7.6,0. 9Hz,1H),2.45-2.34(m,2H),1.35(d,J=15.6Hz,1H),1.27(d,J=12.5Hz,9H),0.97(dd,J=13.6,6.8Hz,12H).

[0210] Comparative Example 1

[0211] Comparative Example 1 is a complex (CAS2745047-34-9) with a methyl substituent on the benzimidazole ligand, which has the least shielding effect on the coordination center.

[0212]

[0213] (1) The synthesis of 2-(3-bromophenyl)-pyridine is the same as in Example 1.

[0214] (2) Synthesis of 1-methyl-1H-benzo[d]imidazole:

[0215] The raw materials used were 1H-benzis[d]imidazole, iodoethane, potassium carbonate, and dimethyl sulfoxide. After heating, filtration, extraction, purification, and rotary evaporation, 1-methyl-1H-benzis[d]imidazole was obtained.

[0216] (3) Synthesis of 1-methyl-2-(3-methoxyphenyl)-1H-benzo[d]imidazole:

[0217] The raw materials used were 1-methyl-1H-benzis[d]imidazole, 1-iodo-3-methoxybenzene, DPPF palladium dichloride, triphenylphosphine, silver carbonate, and water. After heating, filtration, extraction, purification, and rotary evaporation, 1-methyl-2-(3-methoxyphenyl)-1H-benzis[d]imidazole was obtained.

[0218] (4) Synthesis of 3-(1-methyl-1-benzo[d]imidazol-2-yl)phenol:

[0219] The raw materials used were 1-methyl-2-(3-methoxyphenyl)-1H-benzo[d]imidazole and hydrogen bromide. After heating, filtration, extraction, purification, and rotary evaporation, 3-(1-methyl-1-benzo[d]imidazole-2-yl)phenol was obtained.

[0220] (5) Synthesis of 1-methyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzo[d]imidazole:

[0221] 3-(1-methyl-1-benzo[d]imidazol-2-yl)phenol, 2-(3-bromophenyl)pyridine, cuprous iodide, BPPO, potassium phosphate, and DMF were added to a sealed tube. After heating, filtration, extraction, purification, and rotary evaporation, 1-methyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzo[d]imidazolium was obtained.

[0222] (6) Synthesis of Comparative Example 1:

[0223] The raw materials used are 1-methyl-2-(3-(3-(pyridin-2-yl)phenoxy)phenyl)-1H-benzimidazole, dichloro(1,5-cyclooctadiene)platinum(II) and DMF.

[0224] The compound of Comparative Example 1 was obtained by heating reaction, filtration, extraction, purification and rotary evaporation.

[0225] Test Example 1

[0226] The photophysical properties of platinum complexes 1, 2, 3, 19, 21 and the complex of Comparative Example 1 were characterized.

[0227] Representative data on emitter color purity can be obtained from the emission spectra of thin films prepared using a 5% PMMA (polymethyl methacrylate) dichloromethane solution. Specifically, the complex is dissolved in dichloromethane (DCM) at a weight ratio of 5% to form a solution and doped in PMMA to obtain a thin film, and then the resulting solution or film is tested.

[0228] Parallel tests were conducted and compared with those of the comparative complexes; Table 1 shows the emission spectrum data of the complexes. The peak wavelengths of complexes 1, 2, 3, 19, and 21 prepared in Examples 1-5 of this invention are between 524-535 nm, and the full width at half maximum (FWHM) is between 33-63 nm, indicating narrower spectra. The luminescence lifetimes τ of complexes 1, 2, 3, 19, and 21 prepared in Examples 1-5 are between 3.17-3.81 μs, and their luminescence efficiencies Φ in solution all exceed 90%, higher than those in thin films. In Table 1, λ represents the peak wavelength, FWHM, luminescence lifetime τ, and luminescence efficiency Φ of the divalent platinum complexes in solution and thin films.

[0229] Table 1

[0230]

[0231] a / b Measurement data in dichloromethane solution / PMMA.

[0232] As can be seen from the above data, the peak green light wavelength of the divalent platinum complex provided by the embodiments of the present invention is in the range of 524-535nm. Compared with the comparative example of methyl substituent, the half-width is significantly narrower, and the luminous efficiency is greatly improved. This allows for the acquisition of green light with higher saturation. Therefore, it can be used as a green phosphorus photoluminescent material or photoluminescent material for high-definition display with high color purity requirements.

[0233] Figure 1-3 The emission spectra of divalent platinum complexes 1, 2, and 3 in solution and thin film are shown in turn. Under 380 nm ultraviolet light excitation, the emission wavelengths of the three complexes in dichloromethane solution are between 524 and 535 nm, and the emission wavelengths in PMMA are between 527 and 532 nm. The wavelengths of all complexes are in the green light region, and the full width at half maximum (FWHM) of the spectra is relatively narrow, indicating that this series of complexes are good green phosphorescent materials.

[0234] in, Figure 1These are the emission spectra of complex 1 prepared in Example 1 of this invention in solution and thin film. The peak wavelength of the emission spectrum in the dichloromethane solution is 529 nm, with a half-maximum width at half-maximum (FWHM) of 46 nm. The emission spectrum of the polymethyl methacrylate (PMMA) film under UV excitation at a 5% mass concentration (i.e., photoluminescence) peak wavelength is 531 nm, with a FWHM of 33 nm. Both show narrow-band green light spectra, indicating that complex 1 is suitable for green phosphorescence applications. Under 380 nm UV excitation, the emission wavelength in the dichloromethane solution is 529 nm. The emission range of the complex mainly includes green and yellow regions. Due to the large intermolecular space in solution, there is no obvious aggregated emission, exhibiting obvious single-molecule emission. In the PMMA film, the emission peak is similar to that in solution. When the concentration increases, the emission spectrum shows a red shift, indicating that the molecules have a significant aggregated emission effect. The spectral width can be controlled by adjusting the doping concentration, which is also very beneficial for the subsequent fabrication of vapor-deposited devices.

[0235] Figure 2 This is the emission spectrum of complex 2 prepared in Example 2 of the present invention in solution and film; wherein, the peak wavelength of the emission spectrum of dichloromethane solution is 532 nm and the half-width at half-maximum is 48 nm; the peak wavelength of the emission spectrum of polymethyl methacrylate (5%) film is 532 nm and the half-width at half-maximum is 34 nm; indicating that under 380 nm ultraviolet light excitation, both solution and film show similar emission spectra. Compared with the emission spectrum in solution, the half-width at half-maximum in film is significantly wider. The introduction of dimethyl groups increases steric hindrance and suppresses molecular vibration. This molecule has the advantages of ligand center transition characteristics, stable emission spectrum, and high color purity.

[0236] Figure 3 This is the emission spectrum of complex 3 prepared in Example 3 of the present invention in solution and film. The peak wavelength of the emission spectrum from the dichloromethane solution is 535 nm, and the half-width at half-maximum (WHM) is 39 nm. The peak wavelength of the emission spectrum from the polymethyl methacrylate (5%) film is 527 nm, and the WHM is 25 nm. The emission spectrum of complex 3 has a narrower WHM than that of complexes 1 and 2. This indicates that the introduction of the tert-butyl group in complex 3 can slightly increase the energy level of emission and the structural rigidity during emission. Under 380 nm ultraviolet light excitation, both solution and film showed similar emission spectra, with comparable emission wavelengths and WHMs. This molecule is based on complex 1 with the addition of a tert-butyl group. Compared to the spectrum of complex 1, the emission peak WHM is narrower. This type of complex can have its emission range controlled by adjusting the substituent derivation, while retaining its high efficiency, narrow spectrum, and stable emission characteristics.

[0237] Figure 4 It is the complex 1 prepared in Example 1 of this invention. 1H NMR spectrum; Figure 5 It is the complex 2 prepared in Example 2 of this invention. 1 H NMR spectrum; Figure 6 It is the complex 3 prepared in Example 3 of this invention. 1 H NMR spectrum; Figure 4 , Figure 5 and Figure 6 The proton NMR spectrum demonstrates that the complex structure was successfully prepared according to the present invention, and the proton NMR spectrum also shows that the complex can exist independently and stably, and can be separated, purified and characterized.

[0238] Figure 7 This is the mass spectrum of complex 1 prepared in Example 1 of this invention; the mass spectrometry molecular signal shows an M / Z (mass-to-charge ratio) peak of 597.9 [M+H]. + The peak value is consistent with the molecular ion peak of compound 1, indicating that the structure of this complex is the designed structure.

[0239] Figure 8 This is the mass spectrum of complex 2 prepared in Example 2 of the present invention; the mass spectrometry molecular signal shows an M / Z (mass-to-charge ratio of ions) peak of 626.1 [M+H]. + The peak value is consistent with the molecular ion peak of compound 2, indicating that the structure of this complex is the designed structure.

[0240] Figure 9 This is the mass spectrum of complex 3 prepared in Example 3 of the present invention; the mass spectrometry molecular signal shows an M / Z peak of 677.1 [M+Na]. + The peak at which the molecular ion of compound 3 complexes with sodium ions indicates that the structure of this complex is the designed structure.

[0241] Test Example 2

[0242] The band gap and related optical properties of coordination compounds 1, 2, 3, 19, 21, and the coordination compound of Comparative Example 1 are characterized as shown in Table 2 below:

[0243] Photoelectric energy level testing of electroluminescent materials: band gap value (E) of the material g The values ​​of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) were determined by cyclic voltammetry (CV). The entire testing process was conducted on a CHI600D electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) in a glove box. A three-electrode system was constructed using a Pt column as the working electrode, Ag / AgCl as the reference electrode, and a Pt wire as the auxiliary electrode. The testing medium was a 0.1M tetrabutylammonium hexafluorophosphate (Bu4NPF6) solution in dimethylformamide (DMF). Ferrocene (Fc) was added as an internal standard for all measured potentials. In Table 2, the unit is electron volt (eV).

[0244] Table 2

[0245] coordination compounds <![CDATA[E HOMO / eV]]> <![CDATA[E LUMO / eV]]> Eg / eV Complex 1 -4.91 -2.45 2.46 Complex 2 -4.92 -2.45 2.47 Complex 3 -5.08 -2.46 2.62 Complex 19 -4.91 -2.45 2.46 Complex 21 -4.92 -2.45 2.47 Comparative Example -5.12 -2.49 2.63

[0246] As shown in Table 2, the structures of complexes 1, 2, 3, 19, and 21 prepared in Examples 1-5 of this invention are different from those of the complex in Comparative Example 1, resulting in different band gap values ​​(E). g The LUMO values ​​of complexes 1, 2, 3, 19, and 21 are not significantly different. However, the HOMO value of complex 3 differs slightly from that of complexes 1 and 2. This is mainly because the tert-butyl substituent has greater steric hindrance, while the methyl substituent in complexes 1 and 2 has less steric hindrance, is more flexible in rotation, and has relatively less rigidity. Therefore, the energy levels are relatively shallower, resulting in a relatively smaller band gap (Eg).

[0247] Application examples

[0248] Complexes 1, 2, 3, 19, 21 and the complex of Comparative Example 1 were used as luminescent materials and doped into the host material to prepare OLED devices with a doping amount of 5%.

[0249] Figure 10 The diagram shows the structure of an OLED light-emitting device. The OLED device includes an anode, which is generally made of a conductive and transparent material, such as indium tin oxide (ITO), a hole injection layer (HIL, P-HTL, HT+P-dop), a hole transport layer (HTL), a light-emitting layer (EML, GH+GD), an electron transport layer (ETL), and a metal cathode layer (Cathode).

[0250] EML can be a luminescent material comprising one or more emitters and a host.

[0251] EIL stands for Electron Injection Layer, which can be considered part of ETL. HIL can be considered part of HTL. EBL stands for Electron Blocking Layer, which can also be considered part of ETL. EIL, ETL, HTL, and HIL can be single-layer or multi-layer. In addition to the core structure of the device, a cathode capping layer (CPL) can be added, which is used to adjust the optical path and improve the light extraction efficiency.

[0252] ITO is the anode of the OLED device, and Al is the cathode. The device structure is: ITO / HAT-CN (10nm) / NPB (40nm) / TCTA (10nm) / BPCz:Pt (35nm) / TmPyPB (25nm) / Liq (2nm) / Al (110nm). The hole injection layer (HIL) can be, but is not limited to, materials such as HATCN, NDP-9, and Re2O3. The hole transport layer (HTL) can be, but is not limited to, any of these materials. The HT layer includes materials such as TAPC, NPD, TCTA, BPBPA, and 2,6-tBumCPy; the EML layer is a blended layer of a 5%:95% complex of the host material and other materials, including but not limited to CBP, mCBP, 2,6mCPy, mCP, DMIC-CZ, and BQDBC; the EIL layer is an electron injection layer, which can be, but is not limited to, materials such as LiQ and LiF; the ETL layer is an electron transport layer, which can be made of materials such as TmPyPb, TPBi, DPPS, Bphen, and BmPyPb. The device structure includes, but is not limited to, the materials mentioned above.

[0253] The following is the abbreviation of the full name of the above functional materials:

[0254] HATCN (Chinese name: 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzanphenanthrene material; English name: 2,3,6,7,10,11-Hexaazatriphenylenehexacabonitrile);

[0255] NDP-9 (CAS No.: 1282035-75-9, English name: 2,2'-(1,3,4,5,6,8,9,10-Octafluoro-2,7-pyrenediylidene)bis[propanedinitrile];

[0256] Re2O3 (Chinese name: molybdenum trioxide, English name: Molybdenum(VI)oxide);

[0257] TAPC (Chinese name: 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)aniline], English name: 4,4′-cyclohexylidenebis[N,N-bis(p-tolyl)aniline]);

[0258] NPD (Chinese name: N,N'-diphenyl-N,N'-(1-naphthyl)-1,1′-biphenyl-4,4′-diamine; English name: N,N'-Bis-(1-naphthalenyl)-N,N'-bis-phenyl-(1,1′-biphenyl)-4,4′-diamine);

[0259] TCTA (Chinese name: 4,4′,4”-Tris(carbazol-9-yl)triphenylamine, English name: 4,4′,4”-Tris(carbazol-9-yl)triphenylamine);

[0260] BPBPA (Chinese name: 4,4'-bis[N,N-di(biphenyl-4-yl)amino]-1,1'-biphenyl, English name: 4,4'-Bis[N,N-di(biphenyl-4-yl)amino]-1,1'-biphenyl);

[0261] 2,6-tBu-mCPy (Chinese name: 2,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)pyridine; English name: 2,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)pyridine);

[0262] CBP (Chinese name: 4,4'-bis(9-carbazolyl)biphenyl, English name: 4,4'-Bis(9-carbazolyl)-1,1'-biphenyl);

[0263] mCBP (Chinese name: 3,3'-Di(9H-carbazol-9-yl)-1,1'-biphenyl, English name: 3,3'-Di(9H-carbazol-9-yl)-1,1'-biphenyl (purified by sublimation);

[0264] 2,6mCPy (Chinese name: 2,6-di(9-carbazol-9-yl)pyridine; English name: 2,6-Di(9H-carbazol-9-yl)pyridine);

[0265] mCP (Chinese name: 1,3-di-9-carbazolylbenzene, English name: 1,3-Di-9-carbazolylbenzene)

[0266] DMIC-CZ (Chinese name: 7,7-dimethyl-5-phenyl-2-(9-phenyl-3-carbazolyl)-5,7-dihydroindolo[2,1-b]carbazole)

[0267] 7,7-dimethyl-5-phenyl-2-(9-phenyl-9H-carbazole-3-yl)-5,7-dihydroindeno[2,1-b]carbazole);

[0268] BQDBC English name: 7-(4-([1,1'-biphenyl]-4-yl)quinazolin-2-yl)-7H-dibenzo

[0269] [c,g]carbazole CAS: 1831055-87-80;

[0270] LiQ (Chinese name: 8-hydroxyquinoline-lithium, English name: 8-Hydroxyquinolinolato-lithium);

[0271] LiF (Chinese name: lithium fluoride, English name: Lithium fluoride);

[0272] TmPyPb (Chinese name: 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1”-terphenyl]-3,3”-diyl]dipyridine, English name: 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene);

[0273] TPBi (Chinese name: 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, English name: 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene);

[0274] DPPS (Chinese name: diphenyldi[4-(pyridin-3-yl)phenyl]silane, English name: Diphenylbis(4-(pyridin-3-yl)phenyl)silane);

[0275] Bphen (Chinese name: 4,7-diphenyl-1,10-phenanthroline, English name: 4,7-diphenyl-1,10-phenanthroline);

[0276] BmPyPb (Chinese name: 1,3-bis(3,5-dipyridin-3-yl)phenyl)benzene, English name: 1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene);

[0277] Light-emitting devices were fabricated using a top-emitting structure for platinum complexes and comparative (GD) complexes. The device structure was Ag (100 nm) / BPBPA:3wt% HATCN (10 nm) / BQDBC (30 nm) / 2,6-tBu-mCPy (10 nm) / mCBP:GD (94%:6% , 40 nm) / TPBi:Liq (1:1 , 35 nm) / Yb (1 nm) / Ag:Mg (13 nm) / BPBPA (65 nm).

[0278] Figure 11 The emission spectrum of the device prepared using platinum complex 1 in Example 1 is shown. According to the electroluminescence spectrum of the device with 5% platinum complex doped in the luminescent layer, the emission peak is located at 537 nm, which is 6 nm redshifted from its photoluminescence peak in PMMA medium, maintaining the luminescence characteristics of the luminescent complex itself. Its chromaticity coordinates are calculated to be CIE (0.30, 0.64) and the half-maximum width is 25 nm, indicating that this device has a narrow band electroluminescence effect and is suitable for use as a green light emitting device.

[0279] Figure 12 The emission spectrum of the device using platinum complex 2 prepared in Example 2 is shown. According to the electroluminescence spectrum of the device with 5% platinum complex doped in the luminescent layer, the emission peak is located at 533 nm, which is 1 nm redshifted from its photoluminescence peak in PMMA medium. The half-width is similar, maintaining the luminescence characteristics of the luminescent complex itself. Its chromaticity coordinates are calculated to be CIE (0.35, 0.63) and the half-width is 24 nm, indicating that this device has a narrow band electroluminescence effect and is suitable for use as a green light emitting device.

[0280] Figure 13 The emission spectrum of the device prepared using platinum complex 3 in Example 3 of the present invention is shown. According to the electroluminescence spectrum of the device with 5% platinum complex doped in the luminescent layer, the emission peak is located at 538 nm, which is 11 nm redshifted from its photoluminescence peak in PMMA medium. The half-width is similar, maintaining the luminescence characteristics of the luminescent complex itself. Its chromaticity coordinates are calculated to be CIE (0.34, 0.64) and the half-width is 21 nm, indicating that this device has a narrow band electroluminescence effect and is suitable for use as a green light emitting device.

[0281] Figure 14 This is a schematic diagram of the EQE-current density curve of the OLED device prepared by complex 1 in Example 1 of the present invention. The EQE curve shows that the external quantum efficiency of the device exceeds 24.1% at low current density. As the current density increases, the device roll-off is small, indicating that the device prepared by complex 1 has good device luminescence stability.

[0282] Figure 15This is a schematic diagram of the EQE-current density curve of the OLED device prepared by complex 2 in Example 2 of the present invention. The EQE curve shows that the external quantum efficiency of the device exceeds 22.2% at low current density. As the current density increases, the device roll-off is small, indicating that the device prepared by complex 2 has good device luminescence stability.

[0283] Figure 16 This is a schematic diagram of the EQE-current density curve of the OLED device prepared by complex 3 in Example 3 of the present invention. The EQE curve shows that the external quantum efficiency of the device exceeds 20.6% at low current density. As the current density increases, the device roll-off is small, indicating that the device prepared by complex 3 has good luminescence stability.

[0284] Application test cases

[0285] Performance comparison experiments were conducted using light-emitting devices prepared with complexes 1, 2, 3, 19, 21 and comparative examples.

[0286] The performance data of the light-emitting devices prepared using the above-mentioned divalent platinum complex are shown in Table 3. CIE(x,y) refers to the chromaticity coordinate parameters according to the International Commission on Illumination (ICI) standard. The current efficiency (CE) and energy efficiency (PE) data are provided at a device luminance of 1000 cd / m². 2 The values ​​below.

[0287] Table 3

[0288]

[0289] Table 3 shows a comparison of the luminescent performance data of the light-emitting devices prepared by various platinum complexes. The electroluminescence wavelength of the light-emitting device is mainly determined by the photoluminescence of the platinum complex itself, and the purity of the photoluminescence spectrum of the platinum complex itself is directly related to the spectral purity of the electroluminescence. Under the same conditions, the efficiency of the light-emitting device is consistent with the trend of the luminescence quantum efficiency of the platinum complex itself, and the color purity of the light emitted by the light-emitting device is directly related to the spectral color purity of the emitted light under photoexcitation of the doped material itself. Comparing the electroluminescence spectrum of the platinum complex light-emitting device with that of the photoluminescent device in the thin film, it can be seen that the electroluminescence spectrum of the light-emitting device is slightly redshifted compared to that of the thin film photoluminescence spectrum, but the peak wavelength is still located in the green light region (530-540nm), and most of the spectrum is also located in the green light range. The calculated chromaticity coordinates indicate that the light-emitting device belongs to the green light emission device and covers the green light range very well. The light-emitting device prepared by complex 21 has a maximum current efficiency (CE) of 150.82cd / A and a maximum energy efficiency (PE) of 198.5lm / W.

[0290] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A divalent platinum complex, characterized in that, The divalent platinum complex has the structure shown in formula (I): In equation (I): R1 is an alkyl group having at least two carbon atoms; R2-R 15 The same or different, each independently selected from one or more of hydrogen atoms, hydrogen isotopes, fluorine atoms and polyatomic substituents; the polyatomic substituents include substituted or unsubstituted alkyl groups and / or substituted or unsubstituted aryl groups.

2. The divalent platinum complex according to claim 1, wherein, R1 is an alkyl group having at least two carbons, and the alkyl group includes one or more of aryl-substituted alkyl groups, silyl groups, substituted or unsubstituted cycloalkyl groups; Preferably, each R1 is independently selected from deuterated substituents - CDR. a R b and / or -CD2R a , where R a and R b Each is independently selected from C2-C 12 Alkyl, C5-C 30 Aromatic groups, C1-C 12 The alkoxy group or the above-mentioned substituent containing an isotopic atom; preferably, the alkyl group includes one or more of unsubstituted straight-chain alkyl, substituted straight-chain alkyl, unsubstituted cycloalkyl, and substituted cycloalkyl; preferably, the aromatic group includes one or more of unsubstituted aryl, substituted aryl, aryloxy, arylamine, and heteroaryl. Preferably, R a and R b Each is independently selected from unsubstituted straight-chain alkyl and / or aryl-substituted alkyl groups; Preferably, R a and R b Each is independently selected from C2-C 10 alkyl; Preferably, R1 is selected from one or more of 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, butyl, isobutyl, hexafluoroisobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl.

3. The divalent platinum complex according to claim 1, wherein, The polyatomic substituents include one or more of unsubstituted alkyl, aryl-substituted alkyl, fluorinated alkyl, unsubstituted aryl, and alkyl-substituted aryl. Preferably, the polyatomic substituents include C1-C 20 Alkyl, C5-C 30 Aryl groups.

4. The divalent platinum complex according to claim 1 or 2, wherein, R2-R 15 Each is independently selected from deuterated substituents -CDH2, -CD2H, -CD3, -CDR a R b -CD2R a One or more of them, wherein R a and R b Each is independently selected from C1-C 12 Alkyl, C5-C 30 Aromatic groups, C1-C 12 The alkyl group comprises one or more of the above-mentioned substituents containing an isotopic atom, including an alkoxy group or a substituent containing an isotopic atom; preferably, the alkyl group comprises one or more of unsubstituted straight-chain alkyl, substituted straight-chain alkyl, unsubstituted cycloalkyl, and substituted cycloalkyl; preferably, the aromatic group comprises one or more of unsubstituted aryl, substituted aryl, aryloxy, arylamine, and heteroaryl. More preferably, R a and R b Each is independently selected from C1-C 10 Alkyl and / or C5-C 24 Aromatic group; more preferably, the alkyl group includes one or more of aryl-substituted alkyl, silyl, and haloalkyl; more preferably, the aromatic group includes alkyl-substituted aryl and / or aryl-substituted aryl; Preferably R2-R 15 Each is independently selected from unsubstituted deuterated aryl and / or substituted deuterated aryl-Ar-dn, wherein Ar is selected from one or more of aryl, aryl-substituted aryl and alkyl-substituted aryl; and the deuterated hydrogen dn is selected from one deuterated, multiple deuterated, or all hydrogens are deuterated.

5. The divalent platinum complex according to any one of claims 1-4, wherein, The isotopic atom is a deuterium atom or a deuterium-substituted atom; And / or, the alkyl group is selected from one or more of methyl, ethyl, propyl, butyl, pentyl, and hexyl; And / or, the aryl group is selected from one or more of phenyl, naphthyl, and biphenyl; And / or, the cycloalkyl group is selected from one or more of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl.

6. The divalent platinum complex according to any one of claims 1-5, wherein, R2-R 15 Each is independently selected from methyl, benzyl, diphenylmethyl, triphenylmethyl, ethyl, 2-phenylethyl, 2,2-phenylethyl, 2,2,2-trifluoroethyl, n-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-dicyclohexylphenyl, 2,4-dicyclopentylphenyl Propylphenyl, 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-di-tert-butylphenyl, 3,5-diisobutylphenyl One or more of the following: 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, and 2,4,6-tricyclopentylphenyl.

7. The divalent platinum complex according to any one of claims 1-6, wherein, The divalent platinum complex is selected from at least one of the complexes shown in complexes 1 to 30 below:

8. The divalent platinum complex according to any one of claims 1-7, wherein, The divalent platinum complex emits light in dichloromethane solution at a wavelength between 500-540 nm, preferably between 524-535 nm. And / or, the emission wavelength of the divalent platinum complex in polymethyl methacrylate is between 500-540 nm, preferably 527-532 nm.

9. A method for preparing a divalent platinum complex, characterized in that, The preparation method includes the following synthesis steps: (1) Under a protective gas, compound a shown in formula (a) is reacted with compound b shown in formula (b) to obtain pyridine compound c with substituents shown in formula (c); (2) Under a protective gas, the pyridine compound c with substituent shown in formula (c) is reacted with the phenol compound d with substituent shown in formula (d) to obtain compound e shown in formula (e). (3) In the presence of a divalent platinum source and DMF, compound e shown in formula (e) is subjected to a cyclometalation reaction to obtain the divalent platinum complex shown in formula (I); Wherein, the definitions of the groups in formulas (I), (a), (b), (c), (d), and (e) are the same as those in any one of claims 1-7; X in formulas (a), (b), and (c) may be the same or different, and may be F, Br, I, Cl, or OTf, respectively.

10. The method according to claim 9, wherein, In step (2), the preparation of the substituted phenolic compound d includes any one of the following two methods: The first method: (I-2-1) Under a protective atmosphere, the substituted benzo[d]imidazole compound f shown in formula (f) is reacted with compound R1-X to obtain compound g shown in formula (g); (I-2-2) Under a protective gas, compound g, represented by formula (g), is reacted with compound h, represented by formula (h), to obtain compound h, represented by formula (i); (I-2-3) Under a protective gas, compound i, as shown in formula (i), is reacted with halide HX to obtain compound i, as shown in formula (d); The second method: (II-2-1) Under a protective atmosphere, the substituent-containing benzene nitryl compound j shown in formula (j) is reacted with the R1-NH2 compound to obtain compound k shown in formula (k); (II-2-2) Under a protective gas, the compound k shown in formula (k) is reduced to obtain the compound shown in formula (m); (II-2-3) Under a protective atmosphere, compound m, represented by formula (m), is reacted with compound n, represented by formula (n), to obtain compound d; 11. A divalent platinum complex prepared by the preparation method according to claim 9 or 10.

12. The application of a divalent platinum complex according to any one of claims 1-8 and 11 in organic optoelectronic devices.

13. The application of a divalent platinum complex according to any one of claims 1-8 and 11 in a green phosphorescent organic optoelectronic device.

14. An organic optoelectronic device, characterized in that, The organic optoelectronic device includes a substrate, an anode layer, a hole transport layer, a light-emitting layer, an electron transport layer, and a metal cathode layer, wherein at least one of the light-emitting layer, the electron transport layer, and the hole transport layer contains the divalent platinum complex as described in any one of claims 1-8 and 11.

15. The organic optoelectronic device according to claim 14, wherein, The luminescent layer comprises the divalent platinum complex as described in any one of claims 1-8 and 11.

16. The organic optoelectronic device according to claim 14 or 15, wherein, The divalent platinum complex is the luminescent material, host material, or guest material in the luminescent layer.

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