Highly colored divalent platinum complexes

Abstract

The present application relates to high color purity bivalent platinum complex, with chemical formula (I) structure, the compound is applied in organic light emitting diode, has lower driving voltage and higher luminous efficiency, and half width is narrow, color purity is higher, can obtain better quantum efficiency, has potential application in organic electroluminescent device field. The present application also provides an organic electroluminescent device, comprising cathode, anode and organic layer, the organic layer is one or more layers in hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, and at least one layer in organic layer contains the compound in structural formula (I).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light-emitting materials, in particular to a high color purity divalent platinum complex and its application in organic light-emitting diodes. BACKGROUND

[0002] With the increasing demand for information, new intelligent terminal products are emerging, especially electronic products gradually develop towards intelligence, flexibility and portability. Organic electroluminescence (OLEDs) is a new display technology, which has many advantages such as ultra-light and ultra-thin, low power consumption, self-luminescence, wide temperature range, wide color gamut, wide viewing angle, fast response speed, and easy realization of flexible display, and has become an important direction of current material science and industrial development.

[0003] Early developed fluorescent OLEDs can usually only utilize singlet state light-emitting, and the triplet excitons generated in the device cannot be effectively utilized but return to the ground state through non-radiative means, which limits the popularization and use of OLEDs. In 1998, Professor Chi Ming Wong of Hong Kong University first reported the phenomenon of electrophosphorescence. In the same year, Thompson et al. prepared phosphorescent OLEDs using transition metal complexes as light-emitting materials. Phosphorescent OLEDs can efficiently utilize singlet and triplet excitons for light-emitting, and theoretically can achieve 100% internal quantum efficiency, which greatly promotes the commercialization process of OLEDs. The covalent metal-carbon bond of electrophosphorescent metal complexes increases the mixing of metal d orbitals and ligand orbitals, which can also improve the stability of the compound; and due to the strong heavy atom effect, the mixing of metal d orbitals and ligand orbitals can enhance the influence of the metal center on the excited state of the ligand itself, enhance the spin-orbit coupling effect, thereby improve the quantum yield of triplet state and promote efficient phosphorescent radiation relaxation. After nearly two decades of research and development of electrophosphorescent OLEDs, OLED materials have entered the application stage. In the application stage, in order to meet the demand of high-quality full-color light-emitting of components, materials with high quantum efficiency and good color purity performance are essential, which requires the development of new efficient narrow-bandwidth complex materials for OLEDs. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application provides a high color purity divalent platinum complex, which has good photoelectric performance when applied to an organic light-emitting diode.

[0005] The present application also provides an organic light-emitting diode based on the high color purity divalent platinum complex.

[0006] The high color purity divalent platinum complex is a compound having the structure of formula (I):

[0007]

[0008] wherein:

[0009] R 1 to R 23 each independently selected from the group consisting of: hydrogen, deuterium, halogen, amine, carbonyl, carboxyl, sulfanyl, cyano, sulfonyl, phosphine, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted alkenyl having 2-20 carbon atoms, substituted or unsubstituted alkoxy having 1-20 carbon atoms, substituted or unsubstituted aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, or connected or fused into a ring between any two adjacent substituents;

[0010] A1-A4 are selected from the group consisting of: hydrogen, deuterium, halogen, amine, carbonyl, carboxyl, sulfanyl, cyano, sulfonyl, phosphine, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted alkenyl having 2-20 carbon atoms, substituted or unsubstituted alkoxy having 1-20 carbon atoms, aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms; or connected or fused into a ring between any two adjacent substituents;

[0011] the heteroatoms in the heteroaryl are one or more of N, S, O;

[0012] the substitution is by halogen, deuterium, amine, cyano, or C1-C4 alkyl.

[0013] Preferably, R 1 to R 23 each independently selected from the group consisting of: hydrogen, deuterium, halogen, amine, sulfanyl, cyano, substituted or unsubstituted alkyl having 1-6 carbon atoms, substituted or unsubstituted cycloalkyl having 3-6 ring carbon atoms, substituted or unsubstituted alkenyl having 2-6 carbon atoms, substituted or unsubstituted alkoxy having 1-6 carbon atoms, substituted or unsubstituted aryl having 6-12 carbon atoms, or substituted or unsubstituted heteroaryl having 3-6 carbon atoms;

[0014] A1-A4 are selected from the group consisting of: hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted alkenyl having 2-20 carbon atoms, aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms.

[0015] Preferably, R 1 to R 23each independently selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1-6 carbon atoms;

[0016] one of A1-A4 is selected from the group consisting of halogen, cyano, substituted or unsubstituted alkyl having 1-6 carbon atoms, substituted or unsubstituted cycloalkyl having 3-12 ring carbon atoms, substituted or unsubstituted alkenyl having 2-12 carbon atoms, aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, the rest being hydrogen.

[0017] Preferably, R 1 to R 23 each independently selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1-6 carbon atoms;

[0018] one of A1-A4 is selected from the group consisting of halogen, cyano, substituted or unsubstituted alkyl having 1-6 carbon atoms, substituted or unsubstituted cycloalkyl having 3-12 ring carbon atoms, substituted or unsubstituted alkenyl having 2-12 carbon atoms, aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, the rest being hydrogen.

[0019] Further preferably, in general formula (I), R 1 to R 23 each independently selected from the group consisting of: hydrogen, deuterium, methyl, tert-butyl;

[0020] one of A1-A4 is selected from the group consisting of fluorine, cyano, methyl, tert-butyl, phenyl, cyanophenyl, pyridyl; the rest being hydrogen.

[0021] Preferably: wherein R 1 to R 23 R 6 -R 23 is hydrogen.

[0022] wherein R 1 -R 5 at least one of R 1 -R 5 is not hydrogen.

[0023] wherein R 2 , R 4 is not hydrogen, R 1 , R 5 is hydrogen.

[0024] The following list examples of platinum metal complexes according to the present application, but is not limited to the listed structures:

[0025]

[0026]

[0027]

[0028] The precursor of the above metal complex, i.e. the ligand, has the following structural formula:

[0029]

[0030] The application also provides application of the above high-color-purity divalent platinum complex in an organic optoelectronic device, which includes, but is not limited to, organic light-emitting diodes (OLEDs), organic thin-film transistors (OTFTs), organic photovoltaic devices (OPVs), light-emitting electrochemical cells (LCEs) and chemical sensors, preferably OLEDs.

[0031] An organic light-emitting diode (OLED) comprising the above high-color-purity divalent platinum complex, the platinum complex being a light-emitting material in the light-emitting device.

[0032] The organic light-emitting diode in the application comprises a cathode, an anode and an organic layer, the organic layer being one or more of a hole injection layer, a hole transport layer, a light-emitting layer, a hole blocking layer, an electron injection layer and an electron transport layer, and these organic layers do not necessarily exist in each layer; at least one of the hole injection layer, the hole transport layer, the hole blocking layer, the electron injection layer, the light-emitting layer and the electron transport layer contains the platinum complex of formula (I).

[0033] Preferably, the layer containing the high-color-purity divalent platinum complex of formula (I) is the light-emitting layer or the electron transport layer.

[0034] The total thickness of the organic layer of the device of the application is 1-1000 nm, preferably 1-500 nm, and more preferably 5-300 nm.

[0035] The organic layer can be formed into a thin film by evaporation or a solution method.

[0036] The series of novel high-color-purity divalent platinum complex light-emitting materials disclosed in the application show unexpected properties, significantly improve the light-emitting efficiency and device color purity of the compounds, have good thermal stability, and meet the requirements of OLED panels for light-emitting materials.

[0037] The compounds are applied in organic light-emitting diodes, have lower driving voltage and higher light-emitting efficiency, and have obvious improvement in color purity, which has great potential for industrialization of the materials in the field of organic electroluminescent devices. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The organic light-emitting diode device structure of the application is shown in the following figure,

[0039] Where 10 represents the glass substrate, 20 represents the anode, 30 represents the hole injection layer, 40 represents the hole transport layer, 50 represents the light-emitting layer, 60 represents the electron transport layer, 70 represents the electron injection layer, and 80 represents the cathode. Detailed Implementation

[0040] This invention does not require specific methods for synthesizing the materials. The following examples are provided to illustrate the invention in more detail, but are not limited thereto. Unless otherwise specified, all raw materials used in the following synthesis are commercially available products.

[0041] Example 1:

[0042] Synthesis of Complex 22

[0043]

[0044] Synthesis of compound 22b:

[0045] Take a 1000 ml single-necked flask, add 22a (10 g, 59.47 mmol, 1.0 eq) dissolved in methanol (200 ml), and KOH (16.68 g, 297.33 mmol, 5.0 eq) dissolved in water (100 ml). Slowly add the aqueous solution to the reaction mixture, then add a1 (14.28 g, 65.41 mmol, 1.1 eq). Stir the reaction mixture at 45 °C for 16 h. After the reaction is complete, filter the reaction mixture, and slurry the filter cake with methanol (50 ml * 2 times), then dry it. 14 g of white solid was obtained, with a yield of 63.9%. 1 H NMR (400MHz, CDCl3) δ7.68-7.60(m,2H),7.48(s,1H),7.43(d,J=1.6Hz,2H),7.34(d,J=15.9Hz,1H),6.77-6.69(m,2H),3.89(s,3H),1.34(s,18H).

[0046] Synthesis of compound 22c:

[0047] Take a 500ml single-necked flask and add 22b (14g, 38mmol, 1.0eq), a2 (18.42g, 46mmol, 1.2eq), NH4OAc (87.86g, 1.14mol, 30.0eq), and acetic acid (180ml). Under nitrogen protection, react at 130℃ for 4h. After the reaction is complete, filter the reaction solution to obtain a filter cake. Add water (200ml) to the reaction solution and extract with DCM (100ml*2). Dry the organic phase by rotary evaporation. Pulverize the obtained residue and filter cake together with Hex:EA = 20:1 (V / V, total, 200ml), filter, and dry the filter cake to obtain 17g of grayish-white solid, with a yield of 81.38%.

[0048] 1H NMR (400MHz, CDCl3) δ8.30(s,1H),8.03(dd,J=10.3,4.9Hz,3H),7.78(d,J=1.3Hz,1H),7.53(dd,J=14.1,3.2Hz, 4H),7.37(t,J=7.9Hz,1H),6.85(td,J=8.4,2.4Hz,1H),6.77(dd,J=11.0,2.3Hz,1H),3.90(s,3H),1.42(s,18H).

[0049] Synthesis of compound 22d:

[0050] Take a 1000 mL single-necked flask and add 22C (17 g, 31 mmol, 1.0 eq), pinacol diborate (15.8 g, 62 mmol, 2.0 eq), Pd(OAc)₂ (69.84 mg, 0.311 mmol, 0.01 eq), KOAc (9.16 g, 93 mmol, 3.0 eq), X-phos (1.48 g, 3.1 mmol, 0.1 eq), and toluene (250 mL). Under nitrogen protection, react at 80 °C for 16 h. After the reaction is complete, filter the reaction solution and evaporate to dryness. Sonicate the obtained residue with Hex (200 mL) for 1 h, let stand overnight, and allow the product to precipitate. Filter, grind the filter cake, and beat with Hex (200 mL) at 80 °C for 2 h. Filter and dry to obtain 11 g of white solid, with a yield of 75.79%.

[0051] 1 H NMR (400MHz, CDCl3) δ8.46 (s, 1H), 8.26 (d, J = 7.7Hz, 1H), 8.09-8.01 (m, 1H), 7.95 (s, 1H), 7.86 (dd, J=9.4,4.3Hz,2H),7.56-7.48(m,4H),6.87-6.73(m,2H),3.90(s,3H),1.41(s,18H),1.37(s,12H).

[0052] Synthesis of compound a5:

[0053] Take a 250 ml single-necked flask and add a3 (8 g, 29 mmol, 1.0 eq), a4 (17.57 g, 86 mmol, 3.0 eq), Cu (912 mg, 14 mmol, 0.5 eq), CuI (2.73 g, 14 mmol, 0.5 eq), Cs2CO3 (28.05 g, 86 mmol, 3.0 eq), o-phenanthroline (5.17 g, 29 mmol, 1.0 eq), and xylene (150 ml). Under nitrogen protection, react at 140 °C for 48 h. If the reaction is incomplete, continue for another 172 h (17.57 g, 86 mmol, 3.0 eq). If the reaction is still incomplete, continue adding a4 (17.57 g, 86 mmol, 3.0 eq). After the reaction is complete, filter quickly through a silica gel funnel (EA), evaporate the solvent, and perform silica gel column chromatography (eluent: Hex:EA = 20:1). 7 g of white solid was obtained, with a yield of 68.74%.

[0054] 1H NMR (400MHz, CDCl3) δ8.26(dd,J=7.7,1.1Hz,1H),8.19(d,J=7.7Hz,1H),8.00(d,J=5.0Hz,1H),7.45- 7.28(m,5H),7.25(dd,J=9.9,3.3Hz,3H),7.12-7.04(m,2H),6.99(s,1H),6.93(dd,J=5.0,1.4Hz,1H).

[0055] Synthesis of compound 22e:

[0056] Take a 500 mL single-necked flask and add a5 (5 g, 31 mmol, 1.0 eq), 22d (10.04 g, 62 mmol, 2.0 eq), Pd2(dba)3 (258 mg, 0.28 mmol, 0.02 eq), K3PO4-3H2O (9.16 g, 42.27 mmol, 3.0 eq), X-phos (672 mg, 1.41 mmol, 0.1 eq), and toluene / ethanol / water (60 mL / 15 mL / 15 mL). Under nitrogen protection, react at 90 °C for 7 h. After the reaction is complete, add water (100 mL) to the reaction solution, then extract with DCM (200 mL), evaporate to dryness, and separate by silica gel column chromatography (eluent: Hex:EA = 5:1 (V / V)) to obtain 8.5 g of white solid, with a yield of 76.75%.

[0057] 1H NMR (400MHz, CDCl3) δ8.55(s,1H),8.39(d,J=5.0Hz,1H),8.26(dd,J=6.0,3.0Hz,1H),8 .18(dd,J=15.0,7.8Hz,2H),8.07-8.01(m,1H),7.99-7.93(m,2H),7.91(s,1H),7.56(d d,J=18.5,5.3Hz,4H),7.46(s,1H),7.41(dd,J=8.2,5.2Hz,3H),7.33(t,J=7.3Hz,1H), 7.23(d,J=8.2Hz,1H),7.14-6.99(m,6H),6.78-6.71(m,2H),3.87(s,3H),1.40(s,18H).

[0058] Synthesis of compound 22f:

[0059] A 500 mL single-necked flask was filled with 22e (8 g, 10.18 mmol, 1.0 eq), pyridine hydrochloride (80 g), and o-dichlorobenzene (8 mL). The mixture was reacted at 200 °C for 4 h under nitrogen protection. After the reaction was complete, water was added, and the mixture was extracted with DCM (100 mL * 2 times). The organic phase was collected, evaporated to dryness, and separated by silica gel column chromatography (eluent: He:EA = 5:1 (V / V)). 7.5 g of a yellow solid was obtained, with a yield of 92%.

[0060] 1 H NMR (400MHz, CDCl3) δ8.41 (s, 1H), 8.38 (d, J = 5.0Hz, 1H), 8.27 (dd, J = 5.7, 3.3Hz, 1H), 8.2 1(d,J=7.4Hz,1H),8.02(d,J=7.8Hz,1H),7.98-7.92(m,2H),7.92-7.87(m,2H),7.65-7.5 8(m,2H),7.51(d,J=1.6Hz,2H),7.47(s,1H),7.41(dd,J=8.8,5.5Hz,3H),7.33(t,J=7.0H z,1H),7.28(s,1H),7.12(s,2H),7.05(t,J=4.6Hz,4H),6.70-6.60(m,2H),1.42(s,18H).

[0061] Synthesis of complex 22:

[0062] Take a 500ml single-necked flask and add the following reaction:

[0063] 22f (6.9 g, 8.94 mmol, 1.0 eq), K2PtCl4 (4.44 g, 10.74 mmol, 1.2 eq), TBAB (148 mg, 0.45 mmol, 0.05 eq) and acetic acid (750 mL) were used under argon protection and the reaction was carried out at 130°C for 16 h.

[0064] After the reaction was completed, the samples were combined and treated. Excess deionized water was added, causing the solid to precipitate. The solid was filtered, dissolved in dichloromethane, and evaporated to dryness. Separation was then performed by silica gel column chromatography (eluent: DCM). Further separation was performed using Hex:DCM:EA = 2:1:0.2 as the eluent. Recrystallization was then performed using DCM:Hex = 10 ml:70 ml to obtain 7 g of red solid. Further recrystallization using DCM:MeOH = 15 ml:15 ml yielded 6.62 g of red solid, with a yield of 69.1%. 1H NMR (400MHz, CDCl3) δ8.71(d,J=5.6Hz,1H),8.33-8.28(m,1H),8.23(d,J=7.4Hz,2H),8.10-8.03(m,1H),7.77(s,1H),7.60(dd,J=14.6,6. 3Hz, 4H), 7.44 (t, J = 5.7Hz, 3H), 7.38-7.27 (m, 4H), 7.12 (ddd, J = 27.9, 16.7, 8.4Hz, 7H), 6.96 (d, J = 7.2Hz, 1H), 6.51 (s, 1H), 1.45 (s, 18H).

[0065] 13 C NMR (101MHz, CDCl3) δ152.12,151.60,148.11,144.46,144.34,141.23,140.83,139.59,139.19,138.9 3,138.92,137.16,137.14,134.48,130.05,128.38,128.33,128.06,127.49,127.27,127.21,126.91,1 25.82,125.15,124.75,124.17,123.93,123.50,123.47,123.44,122.86,122.84,122.63,122.26,121 .69,121.59,120.47,112.54,108.38,108.22,102.14,101.98,34.96,31.29.ESI-MS(m / z):965.3(M+1)

[0066] Example 2:

[0067]

[0068] Synthesis of compound 38b:

[0069] Take a 1000 ml single-necked flask, add 38a (8 g, 30.5 mmol, 1.0 eq) dissolved in methanol (200 ml), and KOH (8.54 g, 152.5 mmol, 5.0 eq) dissolved in water (100 ml). Slowly add the aqueous solution to the reaction mixture, then add a1 (7.3 g, 33.55 mmol, 1.1 eq). Stir the reaction mixture at 45 °C for 16 h. After the reaction is complete, filter the reaction mixture, and slurry the filter cake with methanol (50 ml * 2 times), then dry it. 7.6 g of white solid was obtained, with a yield of 53.9%.

[0070] ¹H NMR (400MHz, CDCl₃) δ 7.85 (d, J = 2.2Hz, ¹H), 7.71 (d, J = 15.6Hz, ¹H), 7.60–7.52 (m, 2H), 7.48 (t, J = 2.1Hz, ¹H), 7.39 (d, J = 2.1Hz, 2H), 3.87 (s, 3H), 1.42 (s, 9H), 1.36 (s, 18H). Synthesis of compound 38c:

[0071] Take a 500ml single-necked flask and add 38b (7g, 15.12mmol, 1.0eq), a2 (7.3g, 18.15mmol, 1.2eq), NH4OAc (34.96g, 453.6mmol, 30.0eq), and acetic acid (150ml). Under nitrogen protection, react at 130℃ for 4h. After the reaction is complete, filter the reaction solution to obtain a filter cake. Add water (200ml) to the reaction solution and extract with DCM (100ml*2). Dry the organic phase by rotary evaporation. Pulverize the obtained residue and filter cake together with Hex:EA = 20:1 (V / V, total, 200ml), filter, and dry the filter cake to obtain 7.2g of grayish-white solid, with a yield of 74.4%.

[0072] 1 H NMR (400MHz, CDCl3) δ8.22(t,J=1.9Hz,1H),8.10(d,J=2.0Hz,1H),8.00(ddd,J=8.6,1.9,1.2Hz,1H),7.93(d,J=2.0Hz ,1H),7.55(ddd,J=8.1,2.0,1.3Hz,1H),7.53-7.49(m,2H),7.46-7.36(m,4H),3.87(s,3H),1.42(s,9H),1.35(s,27H).

[0073] Synthesis of compound 38d:

[0074] Take a 1000 mL single-necked flask and add 38C (7 g, 10.93 mmol, 1.0 eq), pinacol diboronate (5.51 g, 21.86 mmol, 2.0 eq), Pd(OAc)₂ (24.47 mg, 0.109 mmol, 0.01 eq), KOAc (3.2 g, 32.79 mmol, 3.0 eq), X-phos (0.51 g, 1.09 mmol, 0.1 eq), and toluene (200 mL). Under nitrogen protection, react at 80 °C for 14 h. After the reaction is complete, filter the reaction solution and evaporate to dryness. Sonicate the obtained residue with Hex (200 mL) for 1 h, let stand overnight, and allow the product to precipitate. Filter, grind the filter cake, and slurry it with Hex (200 mL) at 80 °C for 2 h. Filter, dry, and obtain 6.7 g of white solid, with a yield of 90.4%.

[0075] 1 H NMR (400MHz, CDCl3) δ8.08(d,J=2.2Hz,1H),8.05(t,J=1.9Hz,1H),7.93(d,J=2.0Hz,1H),7.78(ddd,J=7.7,1.8,1.1Hz,1H),7.74( ddd,J=7.1,1.9,1.2Hz,1H),7.54-7.49(m,3H),7.43(dd,J=9.0,2.2Hz,3H),3.87(s,3H),1.42(s,9H),1.35(s,27H),1.24(s,12H).

[0076] Synthesis of compound 38e:

[0077] Take a 500 mL single-necked flask and add a5 (1.8 g, 5.1 mmol, 1.0 eq), 38d (7 g, 10.2 mmol, 2.0 eq), Pd2(dba)3 (57.5 mg, 0.10 mmol, 0.02 eq), K3PO4-3H2O (4.07 g, 15.3 mmol, 3.0 eq), X-phos (243 mg, 0.51 mmol, 0.1 eq), and toluene / ethanol / water (60 mL / 15 mL / 15 mL). Under nitrogen protection, react at 90 °C for 7 h. After the reaction is complete, add water (100 mL) to the reaction solution, then extract with DCM (200 mL), evaporate to dryness, and separate by silica gel column chromatography (eluent: Hex:EA = 5:1 (V / V)) to obtain 3.6 g of white solid, with a yield of 80.3%.

[0078] 1H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=2 .0Hz,1H),8.18-8.12(m,1H),8.12-8.07(m,2H),7.93(d,J=2.0Hz,1H),7.89(d d,J=8.4,1.7Hz,2H),7.70-7.64(m,1H),7.65-7.60(m,2H),7.57-7.47(m,5H), 7.45-7.36(m,7H),7.34-7.28(m,2H),3.87(s,3H),1.42(s,9H),1.35(s,27H).

[0079] Synthesis of compound 38f:

[0080] Take a 500 mL single-necked flask, add 38e (3.5 g, 3.97 mmol, 1.0 eq), pyridine hydrochloride (35 g), and o-dichlorobenzene (3.5 mL), and react under nitrogen protection at 200 °C for 4 h. After the reaction is complete, add water and extract with DCM (200 mL * 2 times). Collect the organic phase, evaporate to dryness, and separate by silica gel column chromatography (eluent: He:EA = 5:1 (V / V)). 3 g of yellow solid was obtained, with a yield of 87%.

[0081] 1 H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=2.0 Hz,1H),8.18-8.13(m,1H),8.12-8.08(m,2H),7.90(dd,J=5.4,2.1Hz,2H),7.88(d ,J=1.7Hz,1H),7.70-7.61(m,3H),7.54(t,J=7.0Hz,1H),7.52-7.48(m,4H),7.44- 7.36(m,7H),7.34-7.28(m,2H),7.23(d,J=2.2Hz,1H),1.43(s,9H),1.35(s,27H).

[0082] Synthesis of complex 38:

[0083] Take a 500ml single-necked flask and add the following reaction:

[0084] 38f (2g, 2.3mmol, 1.0eq), KPtCl4 (1.04g, 2.77mmol, 1.2eq), TBAB (37mg, 0.115mmol, 0.05eq) and acetic acid (200mL) were reacted at 130°C for 16h under argon protection.

[0085] After the reaction was completed, the samples were combined and treated. Excess deionized water was added, causing the solid to precipitate. The solid was filtered, dissolved in dichloromethane, and evaporated to dryness. Separation was then performed by silica gel column chromatography (eluent: DCM). Further separation was performed using Hex:DCM:EA = 2:1:0.2 as the eluent. Recrystallization was then performed using DCM:Hex = 10 ml:70 ml to obtain 7 g of red solid. Further recrystallization using DCM:MeOH = 51 ml:15 ml yielded 1.8 g of red solid, with a yield of 75.0%.

[0086] 1H NMR (400MHz, CDCl3) δ9.15(d,J=9.0Hz,1H),8.27(d,J=2.2Hz,1H),8.17-8.12(m,2H),8.09(p,J=3.8Hz,1H),7.77-7.69(m,2H),7.69-7.64(m ,1H),7.60-7.57(m,1H),7.57-7.53(m,3H),7.52-7.45(m,4H),7.44-7 .28(m,8H),7.22-7.15(m,2H),6.91(s,1H),1.40(s,9H),1.35(s,27H).

[0087] 13 C NMR (101MHz, CDCl3) δ161.88,152.13,151.60,148.13,145.08,144.75,144.40,140.67,139.63,139. 61,139.59,139.19,138.93,138.92,137.18,137.14,134.50,130.05,129.70,128.38,128.33,128.06 ,127.49,126.91,125.15,124.99,124.75,124.17,123.93,123.51,123.50,123.47,123.44,122.86,122.84,122.63,122.50,121.69,121.62,121.59,120.47,112.54,34.96,34.92,31.29,31.27,30.41.

[0088] ESI-MS (m / z): 1059.4 (M+1)

[0089] Example 3:

[0090]

[0091] Synthesis of compound 40b:

[0092] Take a 1000 ml single-necked flask, add 10 g of 40a (57.1 mmol, 1.0 eq) dissolved in 200 ml of methanol, and dissolve 16.0 g of KOH (285.4 mmol, 5.0 eq) in 100 ml of water. Slowly add the aqueous solution to the reaction mixture, then add a1 (13.71 g, 62.82 mmol, 1.1 eq). Stir the mixture at 45 °C for 16 h. After the reaction is complete, filter the reaction mixture, and slurry the filter cake with methanol (50 ml * 2 times), then dry it. 12.4 g of white solid was obtained, with a yield of 58.3%. 1 ¹H NMR (400MHz, CDCl₃) δ 8.14 (d, J = 1.9 Hz, 1H), 7.77 (dd, J = 8.5, 1.9 Hz, 1H), 7.72 (d, J = 15.5 Hz, 1H), 7.57 (d, J = 15.4 Hz, 1H), 7.48 (t, J = 2.1 Hz, 1H), 7.39 (d, J = 2.2 Hz, 2H), 7.22 (d, J = 8.4 Hz, 1H), 3.89 (s, 3H), 1.36 (s, 18H). Synthesis of compound 40c:

[0093] Take a 500ml single-necked flask and add 40b (12g, 32mmol, 1.0eq), a2 (15.51g, 38.4mmol, 1.2eq), NH4OAc (74.0g, 960mmol, 30.0eq), and acetic acid (180ml). Under nitrogen protection, react at 130℃ for 4h. After the reaction is complete, filter the reaction solution to obtain a filter cake. Add water (200ml) to the reaction solution and extract with DCM (100ml x 2). Dry the organic phase by rotary evaporation. Pulverize the obtained residue and filter cake together with Hex:EA = 20:1 (V / V, total, 200ml), filter, and dry the filter cake to obtain 13.6g of grayish-white solid, with a yield of 76.8%.

[0094] 1H NMR (400MHz, CDCl3) δ8.22(t,J=2.0Hz,1H),8.13(d,J=1.9Hz,1H),8.10(d,J=2.2Hz,1H),8.00(ddd,J=8.6,1.9,1.2Hz,1H),7.96(d,J=2.2Hz,1H),7.7 1(dd,J=8.3,1.9Hz,1H),7.55(ddd,J=8.1,2.0,1.3Hz,1H),7.50(t,J=2.2H z,1H),7.44-7.36(m,3H),7.19(d,J=8.3Hz,1H),3.91(s,3H),1.35(s,18H).

[0095] Synthesis of compound 40d:

[0096] Take a 1000 mL single-necked flask and add 40C (13 g, 23.49 mmol, 1.0 eq), pinacol diboronate (11.9 g, 46.98 mmol, 2.0 eq), Pd(OAc)₂ (52.76 mg, 0.235 mmol, 0.01 eq), KOAc (6.8 g, 69.47 mmol, 3.0 eq), X-phos (1.12 g, 0.235 mmol, 0.1 eq), and toluene (250 mL). Under nitrogen protection, react at 80 °C for 16 h. After the reaction is complete, filter the reaction solution and evaporate to dryness. Sonicate the obtained residue with Hex (200 mL) for 1 h, let stand overnight, and allow the product to precipitate. Filter, grind the filter cake, and slurry it with Hex (200 mL) at 80 °C for 2 h. Filter, dry, and give 10.5 g of white solid, with a yield of 74.4%.

[0097] 1 H NMR (400MHz, CDCl3) δ8.13(d,J=1.9Hz,1H),8.08(d,J=2.2Hz,1H),8.05(t,J=1 .9Hz,1H),7.96(d,J=2.2Hz,1H),7.78(ddd,J=7.7,1.9,1.2Hz,1H),7.74(ddd, J=7.1,1.9,1.2Hz,1H),7.71(dd,J=8.3,1.9Hz,1H),7.54-7.48(m,2H),7.42(d ,J=2.1Hz,2H),7.19(d,J=8.3Hz,1H),3.91(s,3H),1.35(s,18H),1.24(s,12H).

[0098] Synthesis of compound 40e:

[0099] A 500 mL single-necked flask was filled with a5 (10 g, 28.18 mmol, 1.0 eq), 40d (33.84 g, 56.36 mmol, 2.0 eq), Pd2(dba)3 (322 mg, 0.56 mmol, 0.02 eq), K3PO4-3H2O (22.6 g, 84.85 mmol, 3.0 eq), X-phos (1.3 g, 2.81 mmol, 0.1 eq), and toluene / ethanol / water (120 mL / 30 mL / 30 mL). The mixture was reacted at 90 °C for 7 h under nitrogen protection. After the reaction was complete, 200 mL of water was added to the reaction solution, followed by extraction with DCM (400 mL). The solution was then evaporated to dryness and separated by silica gel column chromatography (eluent: Hex:EA = 5:1 (V / V)) to obtain 15.4 g of a white solid, with a yield of 69.1%.

[0100] 1 H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=2.0Hz,1H) ,8.17-8.12(m,2H),8.12-8.07(m,2H),7.96(d,J=2.2Hz,1H),7.89(dd,J=8.5,1.7Hz,2H ),7.71(dd,J=8.3,1.9Hz,1H),7.69-7.64(m,1H),7.64-7.60(m,2H),7.59-7.48(m,4H), 7.45-7.36(m,6H),7.36-7.28(m,2H),7.19(d,J=8.3Hz,1H),3.91(s,3H),1.35(s,18H).

[0101] Synthesis of compound 40f:

[0102] A 500 mL single-necked flask was filled with 40e (12 g, 15.13 mmol, 1.0 eq), pyridine hydrochloride (96 g), and o-dichlorobenzene (12 mL). The mixture was reacted at 200 °C for 6 h under nitrogen protection. After the reaction was complete, water was added, and the mixture was extracted with DCM (200 mL * 2 times). The organic phase was collected, evaporated to dryness, and separated by silica gel column chromatography (eluent: He:EA = 5:1 (V / V)). 9.34 g of a yellow solid was obtained, with a yield of 79.3%.

[0103] 1H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=2 .0Hz,1H),8.16-8.12(m,1H),8.12-8.05(m,3H),7.93(d,J=2.2Hz,1H),7.89(d d,J=8.5,1.8Hz,2H),7.71-7.58(m,4H),7.54(t,J=7.0Hz,1H),7.52-7.47(m,3 H),7.45-7.36(m,6H),7.36-7.28(m,2H),7.04(d,J=8.6Hz,1H),1.35(s,18H).

[0104] Synthesis of complex 40:

[0105] Take a 500ml single-necked flask and add the following reaction:

[0106] 40f (9 g, 9.25 mmol, 1.0 eq), KPtCl4 (4.18 g, 11.1 mmol, 1.2 eq), TBAB (151.3 mg, 0.46 mmol, 0.05 eq) and acetic acid (900 mL) were reacted at 130°C for 16 h under argon protection.

[0107] After the reaction was completed, the samples were combined and treated. Excess deionized water was added, causing the solid to precipitate. The solid was filtered, dissolved in dichloromethane, and evaporated to dryness. Separation was then performed by silica gel column chromatography (eluent: DCM). Further separation was performed using Hex:DCM:EA = 2:1:0.2 as the eluent. Recrystallization was then performed using DCM:Hex = 10 ml:70 ml to obtain 7 g of red solid. Further recrystallization using DCM:MeOH = 51 ml:15 ml yielded 7.1 g of red solid, with a yield of 79.8%. 1H NMR (400MHz, CDCl3) δ9.07(d,J=8.9Hz,1H),8.30(d,J=1.9Hz,1H),8.26(d,J=1.8Hz,1H),8.18-8.11(m,2H),8.09(t,J=3.8Hz,1H),7.80 -7.69(m,2H),7.69-7.64(m,1H),7.60-7.56(m,1H),7.56-7.53(m,3H),7.52-7.44(m,5H),7.44-7.27(m,8H),7.07(s,1H),1.35(s,18H).

[0108] 13C NMR (101MHz, CDCl3) δ167.39,152.12,151.60,148.09,144.54,144.37,140.79,139.59,139.45,139.1 9,138.93,138.92,137.16,137.14,134.47,132.07,130.91,130.05,128.38,128.33,128.06,127.49,1 26.91,125.96,125.15,124.75,124.17,123.93,123.50,123.47,123.44,122.86,122.84,122.63,122 .31,121.69,121.59,120.47,118.10,115.07,112.54,103.68,34.96,31.29.ESI-MS(m / z):972.3(M+1)

[0109] Example 4:

[0110]

[0111] Synthesis of compound 48b:

[0112] Take a 1000 ml single-necked flask, add 10 g (40.9 mmol, 1.0 eq) of 48a dissolved in 200 ml of methanol, and dissolve 11.4 g (204.5 mmol, 5.0 eq) of KOH in 100 ml of water. Slowly add the aqueous solution to the reaction mixture, then add a1 (9.82 g, 44.99 mmol, 1.1 eq). Stir the reaction mixture at 45 °C for 16 h. After the reaction is complete, filter the reaction mixture, and slurry the filter cake with methanol (50 ml * 2 times), then dry it. 10.8 g of white solid was obtained, with a yield of 59.4%.

[0113] 1 H NMR (400MHz, CDCl3) δ7.77(d,J=7.9Hz,1H),7.72(d,J=15.5Hz,1H),7.57(d,J= 15.6Hz,1H),7.50-7.43(m,3H),7.42-7.36(m,6H),3.90(s,3H),1.36(s,18H).

[0114] Synthesis of compound 48c:

[0115] Take a 500ml single-necked flask and add 48b (10g, 22.5mmol, 1.0eq), a2 (10.91g, 27.0mmol, 1.2eq), NH4OAc (52.0g, 675mmol, 30.0eq), and acetic acid (200ml). Under nitrogen protection, react at 130℃ for 4h. After the reaction is complete, filter the reaction solution to obtain a filter cake. Add water (200ml) to the reaction solution and extract with DCM (100ml*2). Dry the organic phase by rotary evaporation. Pulverize the obtained residue and filter cake together with Hex:EA = 20:1 (V / V, total, 200ml), filter, and dry the filter cake to obtain 10.25g of grayish-white solid, with a yield of 73.2%.

[0116] 1 H NMR (400MHz, CDCl3) δ8.22(t,J=1.9Hz,1H),8.10(d,J=2.2Hz,1H),8.00(ddd,J=8.6,1.9,1.2Hz,1H),7.95(d,J=2.2Hz,1H),7.66(d,J=8.0Hz,1H) ,7.55(ddd,J=8.1,2.0,1.3Hz,1H),7.50(t,J=2.2Hz,1H),7.48-7.44(m, 2H),7.44-7.36(m,6H),7.32(d,J=5.1Hz,1H),3.89(s,3H),1.35(s,18H).

[0117] Synthesis of compound 48d:

[0118] Take a 1000 mL single-necked flask and add 48C (10 g, 16.1 mmol, 1.0 eq), pinacol diboronate (8.16 g, 32.2 mmol, 2.0 eq), Pd(OAc)₂ (36.1 mg, 0.161 mmol, 0.01 eq), KOAc (4.74 g, 48.3 mmol, 3.0 eq), X-phos (0.77 g, 1.61 mmol, 0.1 eq), and toluene (250 mL). Under nitrogen protection, react at 80 °C for 16 h. After the reaction is complete, filter the reaction solution and evaporate to dryness. Sonicate the obtained residue with Hex (200 mL) for 1 h, let stand overnight, and allow the product to precipitate. Filter, grind the filter cake, and slurry it with Hex (200 mL) at 80 °C for 2 h. Filter and dry to obtain 7.68 g of white solid, with a yield of 71.3%.

[0119] 1H NMR (400MHz, CDCl3) δ8.08(d,J=2.2Hz,1H),8.05(t,J=1.9Hz,1H),7.95(d,J=2.2Hz,1H),7.78(ddd,J=7.7,1.8,1.1Hz,1H),7.74(ddd,J=7.1,1.9,1.2H z,1H),7.66(d,J=8.0Hz,1H),7.54-7.49(m,2H),7.48-7.44(m,2H),7.44-7 .35(m,5H),7.32(d,J=5.1Hz,1H),3.89(s,3H),1.35(s,18H),1.24(s,12H).

[0120] Synthesis of compound 48e:

[0121] Take a 500 mL single-necked flask and add a5 (2.47 g, 6.97 mmol, 1.0 eq), 48d (7 g, 10.45 mmol, 1.5 eq), Pd2(dba)3 (78.05 mg, 0.14 mmol, 0.02 eq), K3PO4-3H2O (5.57 g, 20.91 mmol, 3.0 eq), X-phos (1.3 g, 2.81 mmol, 0.1 eq), and toluene / ethanol / water (120 mL / 30 mL / 30 mL). Under nitrogen protection, react at 90 °C for 7 h. After the reaction is complete, add water (200 mL) to the reaction solution, then extract with DCM (400 mL), evaporate to dryness, and separate by silica gel column chromatography (eluent: Hex:EA = 5:1 (V / V)) to obtain 3.9 g of white solid, with a yield of 65.6%.

[0122] 1 H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=1.9Hz,1H),8.19-8.12(m,1H),8.12-8.07(m,2H),7.95(d,J=2.2H z,1H),7.89(dd,J=8.5,1.7Hz,2H),7.70-7.60(m,4H),7.54(t,J=7.0Hz ,1H),7.52-7.35(m,14H),7.35-7.28(m,3H),3.89(s,3H),1.35(s,18H).

[0123] Synthesis of compound 48f:

[0124] A 500 mL single-necked flask was filled with 48e (3.5 g, 4.1 mmol, 1.0 eq), pyridine hydrochloride (35 g), and o-dichlorobenzene (3.5 mL). The mixture was reacted at 200 °C for 6 h under nitrogen protection. After the reaction was complete, water was added, and the mixture was extracted with DCM (200 mL * 2 times). The organic phase was collected, evaporated to dryness, and separated by silica gel column chromatography (eluent: He:EA = 5:1 (V / V)). 2.97 g of a yellow solid was obtained, with a yield of 86.3%.

[0125] 1 H NMR (400MHz, CDCl3) δ8.75(d,J=4.6Hz,1H),8.27(d,J=1.9Hz,1H),8.21(t,J=1.9Hz,1H),8.16-8.12(m,1H),8.12-8.07(m,2H),7.92-7.85( m,3H),7.70-7.60(m,3H),7.57-7.52(m,2H),7.52-7.44(m,5H),7.44-7.36(m,9H),7.34-7.28(m,2H),7.22(d,J=4.9Hz,1H),1.35(s,18H).

[0126] Synthesis of complex 48:

[0127] Take a 500ml single-necked flask and add the following reaction:

[0128] 48f (2.5 g, 2.95 mmol, 1.0 eq), KPtCl4 (1.33 g, 3.54 mmol, 1.2 eq), TBAB (48.3 mg, 0.15 mmol, 0.05 eq) and acetic acid (250 mL) were used in an argon atmosphere and the reaction was carried out at 130°C for 16 h.

[0129] After the reaction was completed, the samples were combined and treated. Excess deionized water was added, causing the solid to precipitate. The solid was filtered, dissolved in dichloromethane, and evaporated to dryness. Separation was then performed by silica gel column chromatography (eluent: DCM). Further separation was performed using Hex:DCM:EA = 2:1:0.2 as the eluent. Recrystallization was then performed using DCM:Hex = 10 ml:70 ml to obtain 7 g of red solid. Further recrystallization using DCM:MeOH = 51 ml:15 ml yielded 2.31 g of red solid, with a yield of 75.1%.

[0130] 1H NMR (400MHz, CDCl3) δ9.08(d,J=8.9Hz,1H),8.26(d,J=1.8Hz,1H),8.17-8.02(m,3H),7.78-7.69(m,2H),7.69-7.65(m,1 H),7.62-7.56(m,1H),7.56-7.52(m,3H),7.52-7.35(m,14H),7.35-7.28(m,2H),7.25(s,1H),7.07(s,1H),1.35(s,18H).

[0131] 13 C NMR (101MHz, CDCl3) δ152.13,151.60,148.09,144.57,144.37,140.83,139.59,139.19,138.93,1 38.92,137.16,137.14,134.47,130.05,129.06,128.52,128.38,128.33,128.06,127.98,127.96, 127.49,126.91,125.49,125.15,124.75,124.17,123.93,123.50,123.47,123.44,122.86,122.84,122.63,122.16,121.69,121.59,120.47,112.88,112.72,112.54,111.49,111.42,34.96,31.29.

[0132] ESI-MS (m / z): 1041.3 (M+1)

[0133] Example 5:

[0134] Under a nitrogen atmosphere, approximately 5.0 mg of thoroughly dried platinum complexes 22, 38, 40, and 48 were weighed. The heating scan rate was set to 10 °C / min, and the scan range was 25-800 °C. The thermal decomposition temperatures were measured to be 452, 476, 457.3, and 483 °C (the temperatures corresponding to a 0.5% thermal weight loss), indicating that these complexes have excellent thermal stability.

[0135] Example 6:

[0136] Organic light-emitting diodes were fabricated using the complex luminescent materials of the present invention. The device structure is shown in [see figure]. Figure 1 .

[0137] First, the transparent conductive ITO glass substrate 10 (with an anode 20 on it) is washed sequentially with detergent solution and deionized water, ethanol, acetone, and deionized water, and then treated with oxygen plasma for 30 seconds.

[0138] Then, a 10 nm thick HATCN layer was deposited on ITO as a hole injection layer 30.

[0139] Then, the compound HT is evaporated to form a 40 nm thick hole transport layer 40.

[0140] Then, a 20 nm thick light-emitting layer 50 is deposited on the hole transport layer. The light-emitting layer is composed of a mixture of platinum complex 22 (20%) and CBP (80%).

[0141] Then, a 40 nm thick AlQ3 layer is deposited on the light-emitting layer as an electron transport layer 60.

[0142] Finally, 1 nm LiF was deposited as the electron injection layer 70 and 100 nm Al was deposited as the device cathode 80.

[0143] Example 7: Organic light-emitting diodes were prepared by replacing complex 22 with complex 38 using the method described in Example 6.

[0144] Example 8: Organic light-emitting diodes were prepared by replacing complex 22 with complex 40 using the method described in Example 6.

[0145] Example 9: Organic light-emitting diodes were prepared by replacing complex 22 with complex 48 using the method described in Example 6.

[0146] Comparative Example 1:

[0147] Organic light-emitting diodes were prepared by replacing complex 22 with complex Ref-1 (CN110872325A) using the method described in Example 6.

[0148] Comparative Example 2:

[0149] Organic light-emitting diodes were prepared by replacing complex 22 with complex Ref-2 (Chem. Sci., 2014, 5, 4819) using the method described in Example 6.

[0150] Comparative Example 3:

[0151] Organic light-emitting diodes were prepared by replacing complex 22 with complex Ref-3 (CN110872325A) using the method described in Example 6.

[0152] Comparative Example 4:

[0153] Organic light-emitting diodes were prepared by replacing complex 22 with complex Ref-4 (CN110872325A) using the method described in Example 6.

[0154] The structural formulas of HATCN, HT, AlQ3, Ref-1, Ref-2, Ref-3, Ref-4 and CBP in the device are as follows:

[0155]

[0156] The organic electroluminescent devices in Examples 6-9, Comparative Examples 1, 2, 3, and 4 at 20 mA / cm 2 The device performance at current density is listed in Table 1:

[0157] Table 1

[0158]

[0159]

[0160] As shown in Table 1, under the same conditions, the platinum complex material of this invention, when applied to organic light-emitting diodes (OLEDs), exhibits a lower driving voltage and higher luminous efficiency. Furthermore, the device lifetime of OLEDs based on the complexes of this invention is significantly better than that of the complexes in the comparative examples, meeting the requirements of the display industry for luminescent materials and demonstrating promising industrialization prospects.

[0161] The above-described embodiments are merely examples and are not intended to limit the scope of the invention. Without departing from the spirit of the invention, various materials and structures in this invention can be replaced with other materials and structures. It should be understood that those skilled in the art can make many modifications and variations based on the concept of the invention without creative effort. Therefore, technical solutions that can be obtained by those skilled in the art through analysis, reasoning, or partial research based on the prior art should all be within the scope of protection defined by the claims.

Claims

1. Divalent platinum complexes, which are compounds having the structure of formula (I): R 1 To R 23 Each is independently selected from: hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl groups having 1-20 carbon atoms, or substituted or unsubstituted alkoxy groups having 1-20 carbon atoms; One or more of A1-A4 are selected from halogen, cyano, substituted or unsubstituted alkyl with 1-6 carbon atoms, or substituted or unsubstituted aryl with 6-30 carbon atoms, and the remainder is hydrogen; The substitution is achieved by halogen, cyano, or C1-C4 alkyl groups. And equation (I) does not have the following structure:

2. The divalent platinum complex according to claim 1, R 1 To R 23 Each is independently selected from: hydrogen, deuterium, halogen, cyano, substituted or unsubstituted alkyl groups having 1-6 carbon atoms, or substituted or unsubstituted alkoxy groups having 1-6 carbon atoms.

3. The divalent platinum complex according to claim 2, wherein R 1 To R 23 Each is independently selected from: hydrogen, deuterium, halogen, or substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.

4. The divalent platinum complex according to claim 3, wherein: R 1 To R 23 Each is independently selected from: hydrogen, deuterium, methyl, or tert-butyl; One or more of A1-A4 are selected from fluorine, cyano, methyl, tert-butyl, phenyl, or cyanophenyl; the rest are hydrogen.

5. The divalent platinum complex according to any one of claims 1-4, wherein R 1 To R 23 Chinese R 6 -R 23 It is hydrogen.

6. The divalent platinum complex according to claim 5, wherein R 1 -R 5 At least one of them is not hydrogen.

7. The divalent platinum complex according to claim 6, wherein R 1 -R 5 Chinese R 2 R 4 Not hydrogen, R 1 R 5 It is hydrogen.

8. The divalent platinum complex according to claim 1 is one of the following compounds:

9. A precursor, i.e., a ligand, of a divalent platinum complex has the following structural formula: R 1 To R 23 A1-A4 as described in any one of claims 1-7, And it is not a structure like the following:

10. The use of the divalent platinum complex according to any one of claims 1-8 in organic light-emitting diodes, organic thin-film transistors, organic photovoltaic devices, luminescent electrochemical cells, or chemical sensors.

11. An organic light-emitting diode, comprising a cathode, an anode, and an organic layer, wherein the organic layer is one or more layers selected from a hole injection layer, a hole transport layer, a light-emitting layer, a hole blocking layer, an electron injection layer, and an electron transport layer, and wherein the organic layer contains a divalent platinum complex as described in any one of claims 1-8.

12. The organic light-emitting diode according to claim 11, wherein the layer containing the divalent platinum complex is a light-emitting layer.

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