4, 7-diaryl thieno [2, 3-d] pyridazine iridium complex as well as preparation method and application thereof

Abstract

The invention relates to the technical field of luminescent materials, in particular to a 4, 7-diaryl thieno [2, 3-d] pyridazine iridium complex as well as a preparation method and application thereof, and structurally designs and synthesizes a 4, 7-diaryl thieno [2, 3-d] pyridazine ligand taking thieno pyridazine as a basic framework. In the synthesis process, an S atom on a thiophene ring of the thiophene double Weinreb amide has electron deficiency, so that a Grignard reagent is only positioned and substituted on one side (the electron-deficient side) with the S atom, and further the positioned and substituted 4, 7-diaryl thieno [2, 3-d] pyridazine ligand and the cyclometalated iridium complex thereof are generated. The benzothienopyridazine ligand disclosed by the invention shows a strong conjugation effect, and after the cyclometalated iridium complex of the benzothienopyridazine ligand is prepared into an organic electroluminescent device, the device shows excellent red light emission.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and in particular to a 4,7-diarylthieno[2,3-d]pyridazine iridium complex, a preparation method and application thereof. Background Art

[0002] In recent years, organic light-emitting diode (OLED) technology has attracted much attention and has many advantages over liquid crystal display (LCD). Its characteristics include low turn-on voltage, high efficiency, light weight, low power consumption and short switching time. In addition, OLED has the characteristics of self-luminescence, no need for backlight, high contrast, ultra-thin design, wide viewing angle, fast response speed, flexible panel, wide operating temperature range, simple structure and process, and is therefore regarded as an emerging application technology in the field of future flat-panel displays. Phosphorescent metal complexes can effectively capture singlet and triplet excitons by introducing transition metals with large molecular weight, thereby increasing the theoretical value of their internal quantum efficiency (IQE) to 100%. Among these materials, iridium complexes have attracted great attention from researchers due to their inherent properties, including short triplet lifetime, strong spin-orbit coupling (SOC), high phosphorescence efficiency and excellent chemical stability.

[0003] Pyridazine compounds have two adjacent N atoms in an aromatic ring. Compared with other common C^N=C type ligands, this C^N=N type compound has no H atom interference on the ortho-N of the coordinated N, and has a stronger bond with the iridium atom, and is easier to coordinate with iridium to form pyridazine cyclometal iridium complexes. The inventor previously synthesized a series of pyridazine metal iridium complexes using pyridazine derivative ligands. For example, the patent application document with Chinese patent application number 201710436528.7 and application publication date September 15, 2017 discloses a pyridazine iridium complex containing an alkyl steric hindered group, and its preparation method and application. The preparation method of the pyridazine iridium complex containing an alkyl steric hindered group in this patent is: first synthesize a pyridazine ligand containing a bicycloalkyl group, and then react the bicycloalkyl pyridazine ligand with IrCl 3 ·(tht) 3 The reaction generates pyridazine tricyclic metallated iridium complexes (CN201710436528.7, Dalton Transactions, 2018, 47, 12243-12252.).

[0004] The Chinese patent application document with the number of 201710436528.7 and the application publication date of April 23, 2020 discloses a thieno[2,3-d]pyridazine-based cyclometalated iridium complex and its preparation method. The patent contains a thieno[2,3-d]pyridazine-based cyclometalated iridium complex, which combines thiophene with good electron mobility with pyridazine ligands, solving the problem of low quantum efficiency of existing pyridazine-based iridium complexes. Tong et al. also published an article titled "High stability and luminance efficiency thieno[2,3-d]pyridazine-based iridium complexes and their applications in high-performance yellow OLEDs" in Dalton Transactions. The study introduced the thieno[2,3-d]pyridazine-based yellow iridium complex, which is used for phosphorescent OLEDs, with an external quantum efficiency of 14.2%, which is 1.4 times the efficiency of the reference PO-01. The thieno[2,3-d]pyridazine-based iridium complex has an intramolecular hydrogen bonding force, which enhances the stability and life of the material. However, the emission wavelength of these compounds is 510-566nm, which belongs to the yellow-green light region with relatively mature research. Compared with efficient green phosphorescent materials, red phosphorescent materials mainly have problems such as poor color purity, low efficiency, and low brightness. Therefore, designing and synthesizing red luminescent materials that can achieve both high color purity and high luminescence efficiency is an urgent problem that needs to be solved.

[0005] In 2017, our research group published an article titled “Synthesis, structure and DFT calculation of a facial tris-cyclometalatedphosphorescent iridium(III)complex containing substituted phthalazineligands” in Volume 466 of Inorganica Chimica Acta. The luminescence wavelength of the complex is 602nm, which belongs to red emission. The maximum brightness of the device is 1330cd m -2). Later, in 2020, our research group published an article titled "The one-pot synthesis of homoligand phenylphthalazine iridium (III) complexes and their application in high efficiency OLEDs" in the 2020 Volume 219 of the Journal of Luminescence. These two articles and other documents disclose phthalazines with red light emission. These results show that increasing the conjugation strength of the ligand is an effective way to achieve red light emission. However, when preparing pyridazine and its derivative ligands, the substituted aromatic groups are randomly substituted on one side. Even if the reaction order of the substituted aromatic groups is changed, only the same ligand and iridium complex structure can be obtained, and it is impossible to explore the effect of the different positions of the substituted aromatic groups on the luminescence properties of such iridium complexes.

[0006] Weinreb amide, also known as N-methyl-N-methoxyamide, has a wide range of uses in organic synthesis. Usually, bis-Weinreb amide can undergo a mono-substitution reaction with Grignard reagents. Even in the case of an excess of organometallic reagents, a di-substitution reaction will not occur due to the formation of a stable metal chelate. The reaction of o-phthalic Weinreb amide (bis-Weinreb amide) with aromatic ring-type Grignard reagents can produce a series of asymmetric phthalazine ligands. However, since o-phthalic bis-Weinreb amide is a symmetrical structure, the Grignard reagent will randomly replace one side. In 2024, our research group published an article titled "Saturated redelectrophosphorescence from novel pyridinopyridazine-based iridium complexes" in Volume 38 of Applied Organometallic Chemistry. It was found that after using pyridine bis-Weinreb amide to replace o-phthalic bis-Weinreb amide, when reacting with aromatic ring reagents, the electron-withdrawing property of the nitrogen atom on pyridine led to the occurrence of a site-directed mono-substitution reaction. Therefore, the present invention proposes to replace the benzene ring with a thiophene ring, and utilizes the sulfur atom in the thiophene ring with electron-withdrawing properties, which can also achieve the purpose of site-directed monosubstitution reaction. Summary of the invention

[0007] One of the purposes of the present invention is to provide a 4,7-diarylthieno[2,3-d]pyridazine iridium complex, which solves the problem that the existing pyridazine cyclometallated iridium complexes are difficult to balance the purity of red light emission and high-efficiency light emission. A cyclometallated ligand is prepared by fusing a thiophene group with a pyridazine group and used to synthesize a thienopyridazine iridium complex, thereby achieving the purpose of further improving the luminescence purity of the iridium complex and obtaining high-efficiency red light emission.

[0008] The second object of the present invention is to provide a method for preparing 4,7-diarylthieno[2,3-d]pyridazine iridium complexes, which has a simple preparation process and is easy to adjust.

[0009] The third object of the present invention is to provide an application of 4,7-diarylthieno[2,3-d]pyridazine iridium complexes.

[0010] The scheme adopted by the present invention to achieve one of the purposes is: a 4,7-diarylthieno[2,3-d]pyridazine iridium complex, the general structural formula of which is at least one of Formula I, Formula II, Formula III, and Formula IV:

[0011]

[0012] In the formula, R 1 is at least one of a hydrogen atom, a fluorine atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and R 1 The number of R is 0-2; 2 is at least one of a hydrogen atom, a fluorine atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and R 2 The number of R is 1-3; 3 is at least one of a hydrogen atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and R 3 The number is 0-2, among which R 2 The number is greater than R 1 .

[0013] The solution adopted by the present invention to achieve the second purpose is: a method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex comprises the following steps:

[0014] (1) Thiophene-2,3-dicarboxylic acid or substituted aromatic ring benzothiophene-2,3-dicarboxylic acid, N,O-dimethylhydroxylamine, acylating agent, alkali agent A and solvent A are added to the reaction system, and the reaction is completed at a certain temperature to obtain a di-Weinreb amide intermediate, i.e., thiophene-2,3-di(N-methoxy-N-methylamide) or substituted aromatic ring benzothiophene-2,3-(N-methoxy-N-methylamide), and the reaction formula is as follows:

[0015]

[0016] (2) Under an inert atmosphere, thiophene-2,3-di(N-methoxy-N-methylamide) or substituted aromatic ring benzothiophene-2,3-(N-methoxy-N-methylamide) obtained in step (1) and R 1 The substituted aromatic ring-type Grignard reagent and solvent B are added to the reaction system and reacted to completion at a certain temperature to obtain a mono-substituted mono-Weinreb amide intermediate. The reaction formula is as follows:

[0017]

[0018] (3) Under an inert atmosphere, the mono-Weinreb amide intermediate obtained in step (2), hydrazine hydrate, a chlorinating agent and solvent C are added to a reaction system, and the reaction is completed at a certain temperature to obtain a mono-chloro-substituted 4-chloro-7-arylthieno[2,3-d]pyridazine intermediate or a 4-chloro-7-aryl-substituted aromatic ring benzothieno[2,3-d]pyridazine intermediate, and the reaction formula is as follows:

[0019]

[0020] (4) Under an inert atmosphere, the 4-chloro-7-arylthieno[2,3-d]pyridazine or 4-chloro-7-aryl substituted aromatic ring benzothieno[2,3-d]pyridazine obtained in step (3) is reacted with R 2 Substituted phenylboronic acid, alkali agent B, catalyst and solvent D are added to the reaction system, and reacted to completion at a certain temperature to obtain 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligands. The reaction formula is as follows:

[0021]

[0022] (5) Preparation of the complex represented by Formula I or Formula III: Under an inert atmosphere, the 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligand obtained in step (4) is mixed with iridium acetylacetonate and solvent E, and the mixture is reacted at a certain temperature until completion to obtain a 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine tricyclic metal iridium complex, and the reaction formula is as follows:

[0023]

[0024] To prepare the complex represented by formula II or IV, the 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligand obtained in step (4), iridium trichloride trihydrate, acetylacetone, alkali agent C and solvent F are mixed under an inert atmosphere and reacted at a certain temperature until completion to obtain a 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine bicyclic metal iridium complex, the reaction formula is as follows:

[0025]

[0026] Preferably, in step (1), the reaction temperature is room temperature, the molar ratio of thiophene-2,3-dicarboxylic acid or 5-tert-butylbenzothiophene-2,3-dicarboxylic acid, acylating agent, alkali agent A and N,O-dimethylhydroxylamine to solvent A is 1:4-6:3-6:2-3:50-500, the acylating agent is at least one of thionyl chloride, phosphorus trichloride, phosphorus pentachloride and oxalyl chloride, the alkali agent A is at least one of pyridine, diethylamine, triethylamine, ammonia water and trimethylamine, and the solvent A is at least one of tetrahydrofuran, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dichloroethane, dimethylformamide, ethanol, methanol, water, benzene, toluene and xylene.

[0027] Preferably, in step (1), the preparation method of thiophene-2,3-dicarboxylic acid is: 3-methyl-2-thiophene carboxylic acid, oxidant and solvent G are added to the reaction system according to a molar ratio of 2-2.5:1:50-500, and reacted at 100-120° C. until completion to obtain thiophene-2,3-dicarboxylic acid, and the reaction formula is as follows:

[0028]

[0029] The oxidant is at least one of potassium permanganate, oxygen, hydrogen peroxide, potassium dichromate, ozone and chlorine dioxide; when potassium permanganate is used as the oxidant, it is better to use it with sodium hydroxide, and the molar ratio of potassium permanganate to sodium hydroxide is 1:10-15.

[0030] The solvent G includes at least one of dimethyl sulfoxide, ethylene glycol, ethanol, isopropanol, methanol, water, dichloromethane, chloroform, benzene, toluene and xylene;

[0031] In step (1), the preparation method of substituted aromatic ring benzothiophene-2,3-dicarboxylic acid is as follows: substituted aromatic ring thiophenol, butynedioic acid ester and solvent H are added to the reaction system according to a molar ratio of 1:2-3:50-500, and reacted at 50-80° C. until completion to obtain substituted aromatic ring benzothiophene-2,3-dicarboxylic acid, and the reaction formula is as follows:

[0032]

[0033] The acetylenedioic acid ester includes at least one of dimethyl acetylenedioate, diethyl acetylenedioate, dipropyl acetylenedioate, etc.;

[0034] The solvent H comprises at least one of ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, ethanol, methanol, water, benzene, toluene and xylene;

[0035] In step (1), the preparation method of N,O-dimethylhydroxylamine is: N,O-dimethylhydroxylamine hydrochloride, alkaline agent C and solvent I are added to the reaction system according to a molar ratio of 1-1.5:1:50-500, and reacted at -20-0°C until completion to obtain N,O-dimethylhydroxylamine, and the reaction formula is as follows:

[0036]

[0037] The alkali agent C includes KOH, NaOH, Ca(OH) 2 or Ba(OH) 2 The solvent I comprises at least one of triethanolamine, diethanolamine, pyridine, dimethyl sulfoxide, ethylene glycol, ethanol, isopropanol, methanol, water, dichloromethane, chloroform, benzene, toluene and xylene.

[0038] Preferably, in step (2), the reaction temperature is room temperature, and thiophene-2,3-di(N-methoxy-N-methylamide) or 5-tert-butylbenzothiophene-2,3-(N-methoxy-N-methylamide) and R 1 The molar ratio of the substituted aromatic ring Grignard reagent to solvent B is 1:2-4:50-500, and the solvent B is at least one of ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, benzene, toluene, and xylene.

[0039] Preferably, in step (2), R 1 The preparation method of the substituted aromatic ring type Grignard reagent is as follows: under an inert atmosphere, R 1 The substituted aromatic ring halogenated benzene, magnesium, initiator and solvent J are added into the reaction system in a molar ratio of 1:1-1.5:0.02-0.05:50-500, and the reaction is completed at -20-0°C to obtain R 1 Substituted aromatic ring type Grignard reagent, the reaction formula is as follows:

[0040]

[0041] The halogenated benzene is at least one of chlorobenzene, bromobenzene and iodobenzene;

[0042] The initiator is at least one of chlorine gas, liquid bromine and iodine;

[0043] The solvent J is at least one of diethyl ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, benzene, toluene and xylene.

[0044] Preferably, in step (3), the reaction temperature is 90-120° C., the molar ratio of the mono-Weinreb amide intermediate to hydrazine hydrate, the chlorinating agent to the solvent C is 1:5-10:3-6:50-500, the chlorinating agent A is at least one of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, aluminum chloride, and phosphorus trifluoride; and the solvent C is at least one of dichloromethane, chloroform, dichloroethane, dimethylformamide, ethanol, methanol, water, benzene, toluene, and xylene.

[0045] Preferably, in step (4), the reaction temperature is 50 to 150° C., 4-chloro-7-arylthieno[2,3-d]pyridazine or 4-chloro-7-aryl-5-tert-butylbenzothieno[2,3-d]pyridazine, R 2 The molar ratio of substituted phenylboronic acid, alkali agent B, catalyst and solvent D is 1:1-2:1-3:0.01-1:50-500;

[0046] The alkaline agent B includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium hydroxide, and potassium hydroxide;

[0047] The solvent D comprises at least one of tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, ethanol, methanol, water, benzene, toluene and xylene;

[0048] The catalyst includes palladium acetate, Pd(PPh 3 ) 4 、Pd(PPh 3 ) 2 Cl 2 、Pd(dppf)Cl 2 Any one of .

[0049] Preferably, in step (5), when preparing the complex represented by formula I or formula III, the reaction temperature is 150-230° C., the molar ratio of 4,7-diarylthieno[2,3-d]pyridazine and 4,7-diaryl-5-tert-butylbenzothieno[2,3-d]pyridazine ligand, iridium acetylacetonate and solvent E is 3-5:1:50-500, and the solvent E is a mixture of two or three or more of o-dichlorobenzene, diethylene glycol monomethyl ether, water, ethoxyethanol, methoxyethanol, glycerol and diethylene glycol;

[0050] When preparing the complex represented by formula II or formula IV, the reaction temperature is 50-100° C., the molar ratio of 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl-5-tert-butylbenzothieno[2,3-d]pyridazine ligand, iridium trichloride trihydrate, acetylacetone, alkali agent C and solvent F is 2-5:1:1-5:0.1-0.5:50-500, the alkali agent C is at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, sodium acetate and ammonia water; the solvent F includes one of water, ethoxyethanol, methoxyethanol, glycerol and diethylene glycol or a mixture of two or more thereof.

[0051] The solution adopted by the present invention to achieve the third purpose is: an application of the 4,7-diarylthieno[2,3-d]pyridazine iridium complex as a luminescent material in the field of organic optoelectronic materials.

[0052] The present invention has the following advantages and beneficial effects:

[0053] (1) The pyridazine ligands of the present invention have strong coordination ability and can coordinate with iridium to generate high-yield pyridazine cyclometallated iridium complexes. In addition, the pyridazine unit has good electron-deficient properties and can effectively improve the electron transport ability of the luminescent material, thereby improving the luminescence efficiency.

[0054] (2) The present invention designs and synthesizes a 4,7-diarylthieno[2,3-d]pyridazine ligand with thienopyridazine as the basic skeleton. During the synthesis process, the S atom on the thiophene ring of the thiophene bis-Weinreb amide is electron-deficient, so that the Grignard reagent will only be substituted on the side with the S atom (the electron-deficient side), thereby generating a 4,7-diarylthieno[2,3-d]pyridazine ligand with positional substitution and its cyclometallated iridium complex.

[0055] (3) The benzothiophene pyridazine ligand of the present invention exhibits a strong conjugation effect, and the cyclometallated iridium complex thereof is used to make an organic electroluminescent device, which exhibits excellent red light emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The UV-visible absorption spectrum and photoluminescence spectrum of the iridium complex Ir1 in the present invention in a dichloromethane solution;

[0057] Figure 2 The UV-visible absorption spectrum and photoluminescence spectrum of the iridium complex Ir2 in the present invention in a dichloromethane solution;

[0058] Figure 3 The UV-visible absorption spectrum and photoluminescence spectrum of the iridium complex Ir3 in the present invention in a dichloromethane solution;

[0059] Figure 4The UV-visible absorption spectrum and photoluminescence spectrum of the iridium complex Ir4 in the present invention in a dichloromethane solution;

[0060] Figure 5 The electroluminescence spectrum of the electroluminescent device of the iridium complex Ir1 in the present invention;

[0061] Figure 6 The electroluminescence spectrum of the electroluminescent device of the iridium complex Ir2 in the present invention;

[0062] Figure 7 The electroluminescence spectrum of the electroluminescent device of the iridium complex Ir3 in the present invention;

[0063] Figure 8 The electroluminescence spectrum of the electroluminescent device of the iridium complex Ir4 in the present invention;

[0064] Fig. 9 The power efficiency-brightness-current efficiency diagram of the electroluminescent device of the iridium complex Ir1-Ir4 in the present invention;

[0065] Fig.10 This is a brightness-external quantum efficiency diagram of the electroluminescent device of the iridium complexes Ir1-Ir4 in the present invention. DETAILED DESCRIPTION

[0066] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0067] Example 1

[0068] Weigh 8.0g (56.3mmol) of 3-methyl-2-thiophene carboxylic acid and 200.0mL of 15% sodium hydroxide aqueous solution into a reaction flask, heat to 80-100°C in air, then add 40.0g (25.3mmol) of potassium permanganate into the reaction flask in batches, and reflux at 100°C for three hours. After the reaction is completed, filter to remove impurities to obtain a clear liquid. Adjust the pH of the liquid with hydrochloric acid until the solid is completely precipitated, filter to remove the liquid, and recrystallize the white solid with water to obtain 4.0g of thiophene-2,3-dicarboxylic acid as a white solid with a yield of 40.8%.

[0069] Weigh 15.0g (154.6mmol) of N,O-dimethylhydroxylamine hydrochloride into a 500mL round-bottom flask, place it in an ice-salt bath, then add 35mL of triethanolamine and 40mL of ethylene glycol, and 5.8g (103.1mmol) of potassium hydroxide. At this time, bubbles will emerge and heat will continue to be released. After the heat release phenomenon stabilizes, the vacuum distillation device is heated to 140°C, and the transparent liquid is waited to flow out until no liquid flows out, and the reaction is completed. The intermediate N,O-dimethylhydroxylamine is obtained as a transparent liquid of 7.7mL (5.6g), with a yield of 59.3%.

[0070] 4.0 g (23.2 mmol) of thiophene-2,3-dicarboxylic acid and 100.0 mL of dry DCM were added to the reaction flask. 11.9 mL (140.0 mmol) of oxalyl chloride was slowly injected under an inert gas atmosphere and an ice bath, and the reaction was carried out at room temperature overnight. After the reaction was completed, the remaining solvent and oxalyl chloride were removed under reduced pressure, and then 100.0 mL of dry THF was added as a solvent. 19.5 mL (140.0 mmol) of dry triethylamine and 6.0 mL (70.0 mmol) of N,O dimethylhydroxylamine were added under an ice bath, and the reaction was carried out at room temperature for four hours. After the reaction was completed, the solvent was removed under reduced pressure, and the mixture was extracted with deionized water and ethyl acetate (EA). The initial product was separated with EA in a silica gel column to obtain 5.4 g of thiophene-2,3-bis (N-methoxy-N-methylamide) as a white solid with a yield of 90.2%.

[0071] 1 H NMR (400 MHz, CDCl 3 )δ7.41(d,J=5.2Hz,1H),7.00(d,J=5.1Hz,1H),3.59(s,3H),3.42(d,J=26.5Hz,3H),3.20(s,6H).

[0072] HRMS((+)-ESI):m / z=281.0569(calcd.281.0572for[C 10 H 14 N 2 O 2 SNa][M+Na + ]).

[0073] Take 2.8g (115.6mmol) of activated magnesium particles and a small amount of iodine particles, mix them and add them to a dry reaction bottle. In a nitrogen atmosphere, add a small amount of dry ether until the magnesium particles are covered, and add a small amount of p-bromotrifluorotoluene. After successful initiation, mix 14.8mL (105.1mmol) of p-bromotrifluorotoluene with an appropriate amount of dry tetrahydrofuran (THF) and slowly add them. After the magnesium particles completely disappear, react at room temperature for two hours to obtain p-bromotrifluorotoluene Grignard reagent.

[0074] 5.4 g (20.9 mmol) of thiophene-2,3-bis(N-methoxy-N-methylamide) was added and reacted at room temperature for 12 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the product was extracted with deionized water and dichloromethane (DCM). The initial product was separated on a silica gel column with an eluent of petroleum ether (PE): DCM = 1:3 to obtain 4.4 g of the intermediate product monosubstituted mono-Weinreb amide intermediate as a white solid with a yield of 62.4%.

[0075] 1 H NMR (400 MHz, CDCl 3 )δ7.84(d,J=8.1Hz,2H),7.66(d,J=8.2Hz,2H),7.62(d,J=5.0Hz,1H),7.23(d,J=5.0Hz,1H),3.31(s,3H),2.82(s,3H). 19 F NMR (376 MHz, CDCl 3 )δ-63.11(s,3F).

[0076] HRMS((+)-ESI):m / z=366.0402(calcd.366.0388for[C 15 H 12 F 3 NO 2 SNa][M+Na + ]).

[0077] 4.4 g (12.8 mmol) of mono-Weinreb amide intermediate, 6.2 mL (128.0 mmol) of hydrazine hydrate and 100.0 mL of dry ethanol were added to the reaction bottle, and the mixture was reacted at 120 °C for 12 hours in an inert gas atmosphere. After the reaction was completed, the white solid was filtered out. 27.5 mL (29.7 mmol) of phosphorus oxychloride and 100.0 mL of dry 1,2-dichloroethane were added to the white solid, and the mixture was reacted at 95 °C for 12 hours in a nitrogen atmosphere. After the reaction was completed, the pH value was adjusted to 7 with ammonia water in an ice bath, and the mixture was extracted with deionized water and DCM. The initial product was separated with pure DCM in a silica gel column to obtain 3.6 g of monochloro-substituted 4-chloro-7-(4-trifluoromethylphenyl)thieno[2,3-d]pyridazine as a pale yellow solid with a yield of 90.6%.

[0078] 1 H NMR (400 MHz, CDCl 3 )δ8.23(d,J=8.0Hz,2H),8.01(d,J=5.4Hz,1H),7.86(d,J=8.1Hz,2H),7.73(d,J=5.5Hz,1H).19 F NMR (376 MHz, CDCl 3 )δ-62.84(s,3F).

[0079] 3.6 g (11.4 mmol) of monochloro-substituted 4-chloro-7-(4-trifluoromethylphenyl)thieno[2,3-d]pyridazine, 9.5 g (68.6 mmol) of potassium carbonate, 4.4 g (17.2 mmol) of 3,5-bis(trifluoromethyl)phenylboronic acid, and 0.3 g of PdCl were added to the sealed tube. 2 (dppf) and 50.0 mL THF and deionized water (V / V=3:2) were mixed and reacted at 100°C for 12 hours under an inert gas atmosphere. After the reaction, the solvent was removed under reduced pressure, and the product was extracted with deionized water and DCM. The initial product was separated on a silica gel column with an eluent of PE:DCM=1:3, and then recrystallized with DCM and PE to obtain 3.4 g of the main ligand 4-(3,5-ditrifluoromethylphenyl)-7-(4-trifluoromethylphenyl)thieno[2,3-d]pyridazine as a white solid with a yield of 65.6%.

[0080] 1 H NMR (400 MHz, CDCl 3 )δ8.49(d,J=1.7Hz,2H),8.39-8.29(m,2H),8.10(s,1H),8.08(d,J=5.5Hz,1H),7.91(d,J=8.1Hz,2H),7.72(d,J=5.5Hz,1H). 19 F NMR (376 MHz, CDCl 3 )δ-62.82(s,6F),-62.83(s,3F).

[0081] HRMS((+)-ESI):m / z=493.0426(calcd.493.0421for[C 21 H 10 F 9 N 2 S][M+H + ]).

[0082] 3.4 g (6.8 mmol) of the main ligand 4-(3,5-ditrifluoromethylphenyl)-7-(4-trifluoromethylphenyl)thieno[2,3-d]pyridazine, 1.0 g (1.7 mmol) of iridium acetylacetonate were added to the reaction bottle, and then 50.0 mL of a mixed solution of o-dichlorobenzene, diethylene glycol monomethyl ether and glycerol (V / V / V=1:2:3) was added as the reaction solvent, and the reaction was carried out at 230°C under an inert atmosphere for 24 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the product was extracted with deionized water and DCM. The initial product was separated in a silica gel column with an eluent of PE:DCM=1:1, and then recrystallized with a mixed solution of PE and DCM to obtain 1.4 g of red powder of the complex Ir1, with a yield of 43.2%.

[0083] 1 H NMR (400 MHz, CDCl 3 )δ8.32(d,J=8.1Hz,3H),8.01(d,J=5.6Hz,3H),7.76(s,3H),7.67(s,6H),7.57(d,J=5.5Hz,3H),7.43-7.34(m,6H). 19 F NMR (376 MHz, CDCl 3 )δ-62.98(s,9F),-63.30(s,18F).

[0084] HRMS((+)-ESI):m / z=1667.0526(calcd.1667.0530for[C 63 H 25 F 27 Ir 6 S 3 ][M+H + ]).

[0085] The structural formula of the product is shown below:

[0086]

[0087] Luminous efficiency: Φ = 88.0% in air-saturated dichloromethane. The UV-visible absorption spectrum and photoluminescence spectrum in dichloromethane solution are as follows: Figure 1 shown.

[0088] Example 2

[0089] Add 3.4g (6.8mmol) of the main ligand 4-(3,5-ditrifluoromethylphenyl)-7-(4-trifluoromethylphenyl)thieno[2,3-d]pyridazine in Example 1, 0.8g (2.0mmol) of iridium trichloride trihydrate and 50.0mL of deionized water and ethylene glycol ethyl ether (V / V=1:3) to the sealed tube, and react at 120°C for 12 hours under an inert gas atmosphere. After the reaction is completed, a red powder of the dichloro bridge intermediate is obtained. Add 0.9g (0.3mmol) of the dichloro bridge intermediate, 0.2g (1.0mmol) of acetylacetone, 0.3g (2.8mmol) of sodium carbonate and 30.0mL of ethylene glycol ethyl ether to the reaction bottle, and react at 120°C for 16 hours under an inert gas atmosphere. After the reaction, the solvent was removed under reduced pressure, and the product was extracted with deionized water and DCM. The initial product was separated on a silica gel column with an eluent of PE:DCM = 1:2, and then recrystallized with a mixed solution of PE and DCM to obtain 0.2 g of red powder of the complex Ir2 with a yield of 42.5%.

[0090] 1 H NMR (400 MHz, CDCl 3 )δ8.45(s,4H),8.21(d,J=8.2Hz,2H),8.13(d,J=5.5Hz,2H),8.07(s,2H), 7.85(d,J=5.5Hz,2H),7.24(s,2H),6.71(s,2H),5.47(s,1H),1.82(s,6H). 19 FNMR (376MHz, CDCl 3 )δ-62.62(s,6F),-62.70(s,12F).

[0091] HRMS((+)-ESI):m / z=1276.0774(calcd.1276.0762for[C 47 H 25 F 18 Ir 4 O 2 S 2 ][M+H + ]).

[0092] The structural formula of the product is shown below:

[0093]

[0094] Luminescence efficiency: Φ = 55.0% in air-saturated dichloromethane. The UV-visible absorption spectrum and photoluminescence spectrum in dichloromethane solution are as follows Figure 2 shown.

[0095] Example 3

[0096] Weigh 2.0g (12.0mmol) of 4-tert-butylthiophenol, 3.5g (30.7mmol) of dimethyl butynedioate and 25.0mL of 1,4-dioxane into a reaction flask, heat to 80°C in air, and react for three hours. After the reaction is completed, remove the solvent under reduced pressure, and separate the initial product in a silica gel column with an eluent of PE:EA=3:1. Mix the obtained solid with an appropriate amount of methanol, sodium hydroxide, and deionized water for heating and hydrolysis. After the hydrolysis is completed, add hydrochloric acid solution to adjust the pH to acidic, filter out the solution, and obtain 3.0g of 5-tert-butylbenzothiophene-2,3-dicarboxylic acid as a yellow solid with a yield of 81.3%.

[0097] 1 H NMR (400 MHz, DMSO-d 6 )δ9.07(s,2H),8.00(dd,J=8.7,0.7Hz,1H),7.87(q,J=2.1Hz,1H),7.67(dd,J=8.7,1.9Hz,1H),1.33(s,9H).

[0098] 3.0 g (10.8 mmol) of 5-tert-butylbenzothiophene-2,3-dicarboxylic acid and 100.0 mL of dry DCM were added to the reaction bottle. 10.5 mL (125.0 mmol) of oxalyl chloride was slowly injected under an inert gas atmosphere and an ice bath, and the reaction was carried out at room temperature overnight. After the reaction was completed, the remaining solvent and oxalyl chloride were removed under reduced pressure, and then 100.0 mL of dry THF was added as a solvent. 17.5 mL (125.0 mmol) of dry triethylamine and 5.5 mL (63.5 mmol) of N,O dimethylhydroxylamine were added under an ice bath, and the reaction was carried out at room temperature for four hours. After the reaction was completed, the solvent was removed under reduced pressure, and the product was extracted with deionized water and EA. The initial product was separated with EA in a silica gel column to obtain 3.1 g of 5-tert-butylbenzothiophene-2,3-di(N-methoxy-N-methylamide) as a white solid with a yield of 78.3%.

[0099] 1 H NMR (400 MHz, CDCl 3 )δ7.98(d,J=8.0Hz,2H),7.91(s,1H),7.84(d,J=8.7Hz,1H),7.75(d,J=8.4Hz,2H),7.63(d,J=8.7Hz,1H),3.24(s,3H),2.98(s,3H),1.39(s,9H).

[0100] HRMS((+)-ESI):m / z=387.1359(calcd.387.1354for[C 18 H24 N 2 O 4 S][M+Na + ]).

[0101] Take 1.1g (47.0mmol) of activated magnesium particles and a small amount of iodine particles, mix and add to a dry reaction bottle, in a nitrogen atmosphere, add a small amount of dry ether until the magnesium particles are covered, add a small amount of p-bromotrifluorotoluene, after successful initiation, dissolve 9.6g (42.7mmol) of p-bromotrifluorotoluene in dry THF and slowly add after mixing. After the magnesium particles completely disappear, react at room temperature for two hours to obtain p-bromotrifluorotoluene Grignard reagent.

[0102] 3.1 g (8.5 mmol) of 5-tert-butylbenzothiophene-2,3-di(N-methoxy-N-methylamide) was added to the bromotrifluorotoluene Grignard reagent and reacted at room temperature for 12 hours. After the reaction, the solvent was removed under reduced pressure, and the product was extracted with deionized water and dichloromethane (DCM). The initial product was separated on a silica gel column with an eluent of petroleum ether (PE): DCM = 1:3 to obtain 2.6 g of a white solid of a mono-substituted mono-Weinreb amide intermediate with a yield of 68.2%.

[0103] 1 H NMR (400 MHz, CDCl 3 )δ7.98(d,J=8.0Hz,2H),7.90(d,J=1.8Hz,1H),7.84(dd,J=8.7,0.8Hz,1H),7.75(d ,J=8.1Hz,2H),7.63(dd,J=8.7,1.9Hz,1H),1.62(s,3H),1.40(s,3H),1.39(s,9H). 19 F NMR (376 MHz, CDCl 3 )δ-63.08(s,3F).

[0104] HRMS((+)-ESI):m / z=472.1193(calcd.472.1170for[C 23 H 22 F 3 NO 3 SNa][M+Na + ]).

[0105] 2.6 g (5.8 mmol) of mono-Weinreb amide intermediate, 2.8 mL (58.2 mmol) of hydrazine hydrate and 50.0 mL of dry ethanol were added to the reaction bottle, and the mixture was reacted at 120 °C for 12 hours in an inert gas atmosphere. After the reaction was completed, the white solid was filtered out. 12.5 mL (13.5 mmol) of phosphorus oxychloride and 50.0 mL of dry 1,2-dichloroethane were added to the white solid, and the mixture was reacted at 95 °C for 12 hours in a nitrogen atmosphere. After the reaction was completed, the pH value was adjusted to 7 with ammonia water in an ice bath, and the mixture was extracted with deionized water and DCM. The initial product was separated with pure DCM in a silica gel column to obtain 1.5 g of monochloro-substituted 4-chloro-7-(4-trifluoromethylphenyl)-5-tert-butylbenzothieno[2,3-d]pyridazine as a pale yellow solid with a yield of 60.8%.

[0106] 1 H NMR (400 MHz, CDCl 3 )δ9.09(dd,J=1.9,0.7Hz,1H),8.32-8.15(m,2H),8.01-7.93(m,1H),7.91-7.86(m,2H),7.84(dd,J=8.5,1.9Hz,1H),1.49(s,9H). 19 F NMR (376 MHz, CDCl 3 )δ-62.79(s,3F).

[0107] In a sealed tube, 1.5 g (3.6 mmol) of monochloro-substituted 4-chloro-7-(4-trifluoromethylphenyl)-5-tert-butylbenzothieno[2,3-d]pyridazine, 3.0 g (21.6 mmol) of potassium carbonate, 1.4 g (5.4 mmol) of 3,5-bis(trifluoromethyl)phenylboronic acid, and 0.1 g of PdCl were added. 2 (dppf) and 50.0 mL THF and deionized water (V / V=3:2) were mixed and reacted at 100°C for 12 hours under an inert gas atmosphere. After the reaction, the solvent was removed under reduced pressure, and the product was extracted with deionized water and DCM. The initial product was separated on a silica gel column with an eluent of PE:DCM=1:3, and then recrystallized with DCM and PE to obtain 1.2 g of the main ligand 4-(3,5-di(trifluoromethyl)phenyl)-7-(4-trifluoromethylphenyl)-5-tert-butylbenzothieno[2,3-d]pyridazine as a white solid with a yield of 56.6%.

[0108] 1 H NMR (400 MHz, CDCl 3)δ8.34(d,J=8.1Hz,2H),8.31(s,2H),8.18(s,1H),7.97(d,J=8.6Hz,1H),7 .92(d,J=8.2Hz,2H),7.74(dd,J=8.6,1.8Hz,1H),7.42(s,1H),1.17(s,9H). 19 FNMR (376MHz, CDCl 3 )δ-62.67(s,6F),-62.78(s,3F).

[0109] HRMS((+)-ESI):m / z=599.1204(calcd.599.1203for[C 29 H 20 F 9 N 2 S][M+H + ]).

[0110] 1.2g (2.0mmol) of the main ligand 4-(3,5-bis(trifluoromethyl)phenyl)-7-(4-trifluoromethylphenyl)-5-tert-butylbenzothieno[2,3-d]pyridazine, 0.3g (0.5mmol) of iridium acetylacetonate, and 50.0mL of a mixed solution of o-dichlorobenzene, diethylene glycol monomethyl ether and glycerol (V / V / V=1:2:3) were added to the reaction bottle as the reaction solvent, and the mixture was reacted at 230°C for 24 hours under an inert atmosphere. After the reaction was completed, the solvent was removed under reduced pressure, and the mixture was extracted with deionized water and DCM. The initial product was separated in a silica gel column with an eluent of PE:DCM=1:1, and then recrystallized with a mixed solution of PE and DCM to obtain 0.5g of red powder of the complex Ir3, with a yield of 48.2%.

[0111] 1 H NMR (400 MHz, CDCl 3 )δ8.33(d,J=8.2Hz,3H),7.95(d,J=8.6Hz,3H),7.70(dd,J=8.6,1.8Hz,3H),7.66(s,3H),7.63( s,6H),7.46(d,J=1.9Hz,3H),7.40(dd,J=8.6,1.9Hz,3H),7.23(d,J=1.7Hz,3H),1.11(s,27H). 19 F NMR (376 MHz, CDCl 3 )δ-62.92(s,9F),-63.12(s,18F).

[0112] HRMS((+)-ESI):m / z=2007.2721(calcd.2007.2668for[C 87 H 54 F 27 Ir 6 S 2 Na][M+Na + ]).

[0113] The structural formula of the product is shown below:

[0114]

[0115] Luminescence efficiency: Φ = 100.0% in air-saturated dichloromethane. The UV-visible absorption spectrum and photoluminescence spectrum in dichloromethane solution are as follows: Figure 3 shown.

[0116] Example 4

[0117] Add 1.2g (2.0mmol) of the main ligand 4-(3,5-bis(trifluoromethyl)phenyl)-7-(4-trifluoromethylphenyl)-5-tert-butylbenzothieno[2,3-d]pyridazine in Example 3, 0.2g (0.5mmol) of iridium trichloride trihydrate and 40.0mL of deionized water and ethylene glycol ether (V / V=1:3) to the sealed tube, and react at 120°C for 12 hours under an inert gas atmosphere. After the reaction is completed, a red powder of the dichloro bridge intermediate is obtained. Add 0.3g (0.1mmol) of the dichloro bridge intermediate, 0.1g (0.5mmol) of acetylacetone, 0.1g (0.8mmol) of sodium carbonate and 15.0mL of ethylene glycol ether to the reaction bottle, and react at 120°C for 16 hours under an inert gas atmosphere. After the reaction, the solvent was removed under reduced pressure, and the product was extracted with deionized water and DCM. The initial product was separated on a silica gel column with an eluent of PE:DCM = 1:2, and then recrystallized with a mixed solution of PE and DCM to obtain 0.2 g of red powder of the complex Ir4 with a yield of 24.3%.

[0118] 1 H NMR (400 MHz, CDCl 3)δ8.37(d,J=8.2Hz,1H),8.29(d,J=8.2Hz,1H),8.25(s,2H),8.10(s,1H),8 .06(d,J=8.6Hz,1H),8.00(s,1H),7.97(d,J=8.6Hz,1H),7.79(d,J=8.6Hz, 1H),7.72(s,1H),7.67-7.63(m,2H),7.62(d,J=8.4Hz,1H),7.25(s,4H),6. 99(s,1H),5.32(s,1H),1.83(s,3H),1.75(s,3H),1.23(s,9H),1.06(s,9H). 19 F NMR (376 MHz, CDCl 3 )δ-62.57(s,3F),-62.73(s,6F),-62.79(s,3F),-63.02(s,6F).

[0119] HRMS((+)-ESI):m / z=1488.2324(calcd.1488.2327for[C 63 H 45 F 18 Ir 4 O 2 S 2 ][M+H + ]).

[0120] The structural formula of the product is shown below:

[0121]

[0122] Luminous efficiency: Φ = 44.0% in air-saturated dichloromethane. The UV-visible absorption spectrum and photoluminescence spectrum in dichloromethane solution are as follows Figure 4 shown.

[0123] It is worth noting that the reaction conditions in the above embodiments are all the optimal reaction conditions for the reaction, and the reaction conditions within the scope of the claims can synthesize the complex of the present invention. In order to avoid redundancy, no examples are given here; in addition, those skilled in the art can reproduce the present invention according to the general formula of the complex of the present invention and the listed related solvents, catalysts and other reagents. Since there are too many examples, several representative examples are selected here, which are sufficient to prove that the complex of the present invention can achieve positional substitution and excellent red light emission, so the examples are not repeated here.

[0124] Performance Testing

[0125] This test is to test the performance of the organic electroluminescent devices of the complexes Ir1-Ir4 in Examples 1-4, and compare their device performance. 3 (3nm) / TAPC(40nm) / TCTA(10nm) / Bepp2:complex(20nm) / Tmpypb nm(35) / LiF(1nm) / Al.

[0126] When the doping concentration of Ir1 is 3% and the doping concentration of Ir2, Ir3 and Ir4 is 1%, the device achieves the best device performance.

[0127] The electroluminescence wavelength of the device based on Ir1 is 576nm ( Figure 5 );

[0128] The electroluminescence wavelength of the Ir2-based device is 608nm ( Figure 6 ), belonging to red light emission;

[0129] The electroluminescence wavelength of the Ir3-based device is 580nm ( Figure 7 );

[0130] The electroluminescence wavelength of the Ir4-based device is 612nm ( Figure 8 ), belonging to red light emission;

[0131] The Ir1-based device has a turn-on voltage of 3.2V and a maximum brightness of 108100cd / m 2 , maximum power efficiency, current efficiency ( Fig. 9 ) and external quantum efficiency ( Fig.10 ) are 53.8lm W -1 , 57.5cd A -1 , 22.4%. When the device brightness reaches the practical brightness of 1000cd m -2 When the device efficiency roll-off value is 9.5%.

[0132] The Ir2-based device has a turn-on voltage of 3.1V and a maximum brightness of 78540cd / m 2 , maximum power efficiency, current efficiency ( Fig. 9 ) and external quantum efficiency ( Fig.10 ) are 31.2lm W -1 , 35.7cd A -1 , 23.6%. When the device brightness reaches the practical brightness of 1000cd m -2 When the device efficiency roll-off value is 13.5%.

[0133] The Ir3-based device has a turn-on voltage of 3.1V and a maximum brightness of 148100cd / m 2, maximum power efficiency, current efficiency ( Fig. 9 ) and external quantum efficiency ( Fig.10 ) are 58.9lm W -1 , 61.8cd A -1 , 24.1%. When the device brightness reaches the practical brightness of 1000cd m -2 When , the device efficiency roll-off value is 12.0%.

[0134] The Ir4-based device has a turn-on voltage of 3.2V and a maximum brightness of 73030cd / m 2 , maximum power efficiency, current efficiency ( Fig. 9 ) and external quantum efficiency ( Fig.10 ) are 31.2lm W -1 , 34.6cd A -1 , 24.1%. When the device brightness reaches the practical brightness of 1000cd m -2 When , the device efficiency roll-off value is 15.0%.

[0135] In general, all devices showed high device efficiency, with external quantum efficiency higher than 22.0%, and small device roll-off values. In addition, the device light color of the bicyclic complexes Ir2 and Ir4 successfully reached the red light range. Due to the large conjugation provided by benzothiophene pyridazine, the emission wavelength of the device made by Ir4 was red-shifted to 612nm, and the device had the best overall performance.

[0136] Furthermore, our research group published an article entitled “Saturated red electrophosphorescence from novel pyridinopyridazine-based iridium complexes” in the 38th volume of the journal Applied Organometallic Chemistry. The study reported a pyridinopyridazine tricyclic iridium complex, whose device electroluminescent wavelength was 626nm, successfully achieving red light emission. However, the brightness and efficiency of the device were 2967cd m -2 、10.6lm W -1 , 13.5cd A -1 The results show that the complex of the present invention has achieved a good balance between the purity of red luminescence and high luminescence efficiency.

[0137] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A 4,7-diarylthieno[2,3-d]pyridazine iridium complex, characterized in that: The general structural formula of this type of complex is at least one of Formula I, Formula II, Formula III, and Formula IV: In the formula, R1 is at least one of a hydrogen atom, a fluorine atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and the number of R1 on the same aromatic ring is 0-2; R2 is at least one of a hydrogen atom, a fluorine atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and the number of R2 on the same aromatic ring is 1-3; R3 is at least one of a hydrogen atom, an alkyl group with 1 to 8 carbon atoms, or a fluoroalkyl group, and the number of R3 on the same aromatic ring is 0-2, wherein the number of R2 is greater than R1.

2. A method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1, characterized in that: The following steps are involved: (1) Thiophene-2,3-dicarboxylic acid or substituted aromatic ring benzothiophene-2,3-dicarboxylic acid, N,O-dimethylhydroxylamine, acylating agent, alkali agent A and solvent A are added to the reaction system, and the reaction is completed at a certain temperature to obtain a Weinreb amide intermediate, i.e., thiophene-2,3-di(N-methoxy-N-methylamide) or substituted aromatic ring benzothiophene-2,3-(N-methoxy-N-methylamide), and the reaction formula is as follows: (2) Under an inert atmosphere, the thiophene-2,3-di(N-methoxy-N-methylamide) or substituted aromatic ring benzothiophene-2,3-(N-methoxy-N-methylamide) obtained in step (1), the R1 substituted aromatic ring type Grignard reagent and solvent B are added to the reaction system, and the reaction is completed at a certain temperature to obtain a mono-substituted mono-Weinreb amide intermediate, and the reaction formula is as follows: (3) Under an inert atmosphere, the mono-Weinreb amide intermediate obtained in step (2), hydrazine hydrate, a chlorinating agent and solvent C are added to a reaction system, and the reaction is completed at a certain temperature to obtain a mono-chloro-substituted 4-chloro-7-arylthieno[2,3-d]pyridazine intermediate or a 4-chloro-7-aryl-substituted aromatic ring benzothieno[2,3-d]pyridazine intermediate, and the reaction formula is as follows: (4) Under an inert atmosphere, the 4-chloro-7-arylthieno[2,3-d]pyridazine or 4-chloro-7-aryl substituted aromatic ring benzothieno[2,3-d]pyridazine obtained in step (3), R2 substituted phenylboronic acid, alkali agent B, catalyst and solvent D are added to the reaction system, and reacted at a certain temperature until completion to obtain 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligand, and the reaction formula is as follows: (5) Preparation of the complex represented by Formula I or Formula III: Under an inert atmosphere, the 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligand obtained in step (4) is mixed with iridium acetylacetonate and solvent E, and the mixture is reacted at a certain temperature until completion to obtain a 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine tricyclic metal iridium complex, and the reaction formula is as follows: To prepare the complex represented by formula II or IV, the 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine ligand obtained in step (4), iridium trichloride trihydrate, acetylacetone, alkali agent C and solvent F are mixed under an inert atmosphere and reacted at a certain temperature until completion to obtain a 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl substituted aromatic ring benzothieno[2,3-d]pyridazine bicyclic metal iridium complex, the reaction formula is as follows:

3. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (1), the reaction temperature is room temperature, the molar ratio of thiophene-2,3-dicarboxylic acid or 5-tert-butylbenzothiophene-2,3-dicarboxylic acid, acylating agent, alkali agent A and N,O-dimethylhydroxylamine to solvent A is 1:4-6:3-6:2-3:50-500, the acylating agent is at least one of thionyl chloride, phosphorus trichloride, phosphorus pentachloride and oxalyl chloride, the alkali agent A is at least one of pyridine, diethylamine, triethylamine, ammonia water and trimethylamine, and the solvent A is at least one of tetrahydrofuran, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dichloroethane, dimethylformamide, ethanol, methanol, water, benzene, toluene and xylene.

4. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (1), the preparation method of thiophene-2,3-dicarboxylic acid is: 3-methyl-2-thiophene carboxylic acid, oxidant and solvent G are added to the reaction system according to a molar ratio of 2-2.5:1:50-500, and reacted at 100-120° C. until completion to obtain thiophene-2,3-dicarboxylic acid, and the reaction formula is as follows: The oxidant is at least one of potassium permanganate, oxygen, hydrogen peroxide, potassium dichromate, ozone, and chlorine dioxide; The solvent G includes at least one of dimethyl sulfoxide, ethylene glycol, ethanol, isopropanol, methanol, water, dichloromethane, chloroform, benzene, toluene and xylene; In step (1), the preparation method of substituted aromatic ring benzothiophene-2,3-dicarboxylic acid is as follows: substituted aromatic ring thiophenol, butynedioic acid ester and solvent H are added to the reaction system according to a molar ratio of 1:2-3:50-500, and reacted at 50-80° C. until completion to obtain substituted aromatic ring benzothiophene-2,3-dicarboxylic acid, and the reaction formula is as follows: The acetylenedioic acid ester includes at least one of dimethyl acetylenedioate, diethyl acetylenedioate, dipropyl acetylenedioate, etc.; The solvent H comprises at least one of ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, ethanol, methanol, water, benzene, toluene and xylene; In step (1), the preparation method of N,O-dimethylhydroxylamine is: N,O-dimethylhydroxylamine hydrochloride, alkaline agent C and solvent I are added to the reaction system according to a molar ratio of 1-1.5:1:50-500, and reacted at -20-0°C until completion to obtain N,O-dimethylhydroxylamine, and the reaction formula is as follows: The alkali agent C includes one of KOH, NaOH, Ca(OH)2 or Ba(OH)2, and the solvent I includes at least one of triethanolamine, diethanolamine, pyridine, dimethyl sulfoxide, ethylene glycol, ethanol, isopropanol, methanol, water, dichloromethane, chloroform, benzene, toluene and xylene.

5. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (2), the reaction temperature is room temperature, the molar ratio of thiophene-2,3-di(N-methoxy-N-methylamide) or 5-tert-butylbenzothiophene-2,3-(N-methoxy-N-methylamide) to R1 substituted aromatic ring type Grignard reagent to solvent B is 1:2-4:50-500, and the solvent B is at least one of diethyl ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, benzene, toluene and xylene.

6. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (2), the preparation method of the R1 substituted aromatic ring type Grignard reagent is: under an inert atmosphere, R1 substituted aromatic ring halogenated benzene, magnesium, initiator and solvent J are added to the reaction system according to a molar ratio of 1:1-1.5:0.02-0.05:50-500, and reacted at -20-0°C until complete to obtain the R1 substituted aromatic ring type Grignard reagent, and the reaction formula is as follows: The halogenated benzene is at least one of chlorobenzene, bromobenzene and iodobenzene; The initiator is at least one of chlorine gas, liquid bromine and iodine; The solvent J is at least one of diethyl ether, tetrahydrofuran, 1,4-dioxane, acetonitrile, dimethyl sulfoxide, dichloromethane, chloroform, dimethylformamide, benzene, toluene and xylene.

7. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (3), the reaction temperature is 90-120° C., the molar ratio of the mono-Weinreb amide intermediate to hydrazine hydrate, the chlorinating agent to the solvent C is 1:5-10:3-6:50-500, the chlorinating agent is at least one of phosphorus oxychloride, thionyl chloride, phosphorus pentachloride, aluminum chloride, and phosphorus trifluoride; and the solvent C is at least one of dichloromethane, chloroform, dichloroethane, dimethylformamide, ethanol, methanol, water, benzene, toluene, and xylene.

8. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (4), the reaction temperature is 50 to 150° C., and the molar ratio of 4-chloro-7-arylthieno[2,3-d]pyridazine or 4-chloro-7-aryl-5-tert-butylbenzothieno[2,3-d]pyridazine, R2-substituted phenylboronic acid, alkali agent B, catalyst and solvent D is 1:1 to 2:1 to 3:0.01 to 1:50 to 500; The alkaline agent B includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium hydroxide, and potassium hydroxide; The solvent D comprises at least one of tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, dimethyl sulfoxide, ethanol, methanol, water, benzene, toluene and xylene; The catalyst includes any one of palladium acetate, Pd(PPh3)4, Pd(PPh3)2Cl2, and Pd(dppf)Cl2.

9. The method for preparing the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1 according to claim 2, characterized in that: In step (5), when preparing the complex represented by formula I or formula III, the reaction temperature is 150-230° C., the molar ratio of 4,7-diarylthieno[2,3-d]pyridazine and 4,7-diaryl-5-tert-butylbenzothieno[2,3-d]pyridazine ligand, iridium acetylacetonate and solvent E is 3-5:1:50-500, and the solvent E is a mixture of two or three or more of o-dichlorobenzene, diethylene glycol monomethyl ether, water, ethoxyethanol, methoxyethanol, glycerol and diethylene glycol; When preparing the complex represented by formula II or formula IV, the reaction temperature is 50-100° C., the molar ratio of 4,7-diarylthieno[2,3-d]pyridazine or 4,7-diaryl-5-tert-butylbenzothieno[2,3-d]pyridazine ligand, iridium trichloride trihydrate, acetylacetone, alkali agent C and solvent F is 2-5:1:1-5:0.1-0.5:50-500, the alkali agent C is at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, sodium acetate and ammonia water; the solvent F includes one of water, ethoxyethanol, methoxyethanol, glycerol and diethylene glycol or a mixture of two or more thereof.

10. Use of the 4,7-diarylthieno[2,3-d]pyridazine iridium complex according to claim 1, characterized in that: It is used as a luminescent material in the field of organic optoelectronic materials.

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