Boron-containing fused ring compound based on 2H-isoindole and organic electroluminescent device thereof

Abstract

According to the boron-containing fused ring compound based on 2H-isoindole and the organic electroluminescent device thereof, boron is contained, a large pi conjugated group is adopted as a parent structure, separation of HOMO and LUMO is achieved through the resonance effect of boron atoms and nitrogen atoms, the multiple resonance thermal activation delayed fluorescence effect is generated, most of the molecular skeletons of the compound are six-membered rings, and the molecular skeletons of the compound are different. The skeleton structure of the fused ring compound provided by the invention contains 2H-isoindole with a five-membered ring structure, so that the material molecules have asymmetry, the SOC is increased, the anti-intersystem transition rate is increased, the EST is reduced, the skeleton system of the MR-TADF material is enriched, and meanwhile, different substituent groups are introduced into the rigid skeleton, so that the molecular weight of the MR-TADF material is increased. Further adjustment on the delayed fluorescence lifetime and the half-peak width is realized. A B-N polar bond of the compound is doped into an MR resonance skeleton to serve as a luminescent material, the luminescent material has remarkable advantages in the aspect of photoelectric properties, and when the luminescent material serves as a luminescent material in an OLED device, the luminescent material has the remarkable advantages of regulating light color, improving quantum yield and prolonging the service life of the device.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and in particular relates to a boron-containing condensed ring compound based on 2H-isoindole and an organic electroluminescent device thereof. Background Art

[0002] Since Dr. Ching-Yun Deng of Kodak Company reported the organic light-emitting diode (OLED) in 1978, OLED technology has attracted extensive attention and research in the past three decades. Compared with cathode ray tubes, liquid crystal displays and plasma display panels, OLED has the advantages of wide viewing angle, self-luminescence, low power consumption, ultra-thin and ultra-light, and fast response speed, so it is hailed as the most promising new generation display technology after liquid crystal display technology.

[0003] The core of OLED display technology is the light-emitting layer technology, in which the properties of the light-emitting material directly determine the properties of the OLED device. The light-emitting material has gone through fluorescent materials, phosphorescent materials, and finally the third-generation thermally activated delayed fluorescence (TADF) light-emitting materials. Currently, TADF has been widely studied by scientific researchers. The luminescence principle of TADF molecules is that due to its molecular structure design, it has a small singlet-triplet energy level difference (△E ST ), which allows the triplet state (T1) excitons generated under electrical excitation to return to the singlet state (S1) through the reverse intersystem crossing (RISC) process, and then return to the ground state (S0) through the radiation transition channel to emit delayed fluorescence, thereby achieving a theoretical internal quantum efficiency of 100%. In order to obtain a smaller △E ST The most widely used strategy in designing TADF molecules is to use the donor group (D) and the acceptor group (A) to form a mutually twisted configuration, thereby achieving effective separation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the molecule. Although the efficiency of TADF materials based on this design is comparable to that of phosphorescent materials, this design will inevitably increase the structural relaxation and Stokes shift of the material in the excited state, resulting in the material presenting a wider (half-maximum width FWHM greater than 70nm) electroluminescent spectrum, thereby reducing the color purity of the luminescence, which is extremely unfavorable for OLED high-resolution display.

[0004] The problem of wide half-width of the electrospectral spectrum of TADF materials has been troubling researchers until 2016, when the research team of Takuji Hatakeyama of Kwansei Gakuin University in Japan creatively proposed the multi-resonance effect-induced thermally activated delayed fluorescence (MR-TADF) material, which achieved high color purity and attracted widespread attention from the academic community. MR-TADF design strategy: In MR-TADF molecules, HOMO and LUMO separation is achieved through opposite resonance effects on the same π-conjugated plane. Usually, it exhibits short-range charge transfer characteristics from its LUMO, which is located on the electron-withdrawing atom (B) and relative to their ortho and para positions, and the HOMO will be confined to the electron-donating atom (N, O or S) and the meta position relative to the electron-withdrawing atom. Therefore, the MR effect reduces structural relaxation and suppresses vibrational electron coupling, which leads to a narrow emission half-width (FWHM). And OLED devices based on such materials all show advantages such as high color purity (FWHM < 30nm) and high external quantum efficiency (EQE max> 20%).

[0005] MR-TADF has been widely studied since 2016, but its molecular skeleton is mostly a six-membered ring. Although MR-TADF molecules show TADF characteristics, they usually have a relatively large energy splitting (ΔE ST ), which leads to slow reverse intersystem crossing (RISC), thereby prolonging the delayed fluorescence (DF) lifetime. As a result, many MR-TADF molecules suffer from severe triplet-involved quenching, which destroys the electroluminescence (EL) efficiency and causes a large efficiency roll-off at high brightness. Summary of the invention

[0006] In view of this, the present invention provides a boron-containing fused ring compound based on 2H-isoindole and an organic electroluminescent device thereof. The skeleton structure of the fused ring compound contains a 2H-isoindole structure with a five-membered ring, which makes the material molecule asymmetric, can increase SOC, improve the anti-system transition rate, reduce △EST, and enrich the skeleton system of MR-TADF materials. The boron-nitrogen fused ring compound based on 2H-isoindole of the present invention is applied to a specific light-emitting device, which has a high anti-system transition rate and reduces △E ST characteristics.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The first technical purpose of the present invention is to provide a boron-containing fused ring compound based on 2H-isoindole and an organic electroluminescent device thereof. The general structural formula of the boron-containing fused ring compound of 2H-isoindole and the organic electroluminescent device thereof is as follows:

[0009]

[0010] Wherein n1 and n2 are each independently an integer greater than or equal to 1;

[0011] Wherein X1 and X2 are the same or different, and are each independently one of O, S, and NR4;

[0012] Wherein ring Ar1 and ring Ar2 are the same or different, and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heteroaromatic ring, a substituted or unsubstituted five-membered aromatic heterocycle, and a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered aromatic heterocycle and a five-membered aromatic heterocycle, and the aromatic condensed ring unit is connected to B, N, O or S via a six-membered aromatic ring, a six-membered aromatic heterocycle or a five-membered aromatic heterocycle.

[0013] wherein R1, R2, R3 and R4 are each independently selected from H, F, Cl, Br, I, -CN, O-R6, -S-R6, -Se-R6,

[0014]

[0015] A substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, a substituted or unsubstituted C5-C60 heteroaromatic group;

[0016] The R6, R7 and R8 are each independently selected from H, F, Cl, Br, I, -OH, -SH, -NH2, a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, a substituted or unsubstituted C5-C60 heteroaromatic group; the heteroatoms in the heteroaromatic group are selected from one or more of Si, Ge, N, P, O, S and Se.

[0017] Furthermore, the boron-containing fused ring compound of 2H-isoindole specifically has the following structure, but is not limited thereto:

[0018]

[0019]

[0020]

[0021] The preparation method and conditions of the 2H-isoindole-based boron-containing fused ring compound of the present invention can refer to the steps and conditions of similar reactions in the art. The present invention preferably has the following preparation method.

[0022] A specific embodiment of the method for preparing the boron-containing fused ring compound based on 2H-isoindole of the specific structure listed above of the present invention comprises the following steps:

[0023] (1) using a bromine-substituted 2H-isoindole compound and other heterocyclic compounds as raw materials, adding a base substance, a catalyst, and a solvent thereto, and reacting to obtain an intermediate;

[0024] (2) Boron tribromide is used as a boron source and N,N-diisopropylethylamine (iPr2EtN) is used as an additive to introduce boron atoms into o-dichlorobenzene (o-DCB) at 180° C. to prepare the 1H-indene-based boron-nitrogen fused ring compound.

[0025] The bromine-substituted 2H-isoindole compound is:

[0026]

[0027] The synthesis method of the bromine-substituted 2H-isoindole compound is:

[0028]

[0029] The general formula for the synthesis of the above target compound is:

[0030]

[0031] Furthermore, the present invention also claims to protect the application of the above-mentioned boron-containing fused ring compound of 2H-isoindole, which can be used in the preparation of organic electroluminescent devices.

[0032] Furthermore, the boron-containing fused ring compound based on 2H-isoindole of the present invention is used as a light-emitting layer material of an organic electroluminescent device.

[0033] The beneficial effects of the present invention are:

[0034] The boron-containing fused ring compound based on 2H-isoindole of the present invention is a new MR-TADF material with a five-membered ring and an acene ring structure as the central ring of the molecular skeleton, which can achieve high color purity and greatly enrich the MR-TADF material system. Due to the introduction of asymmetric five-membered rings in the molecular skeleton of this type of material, SOC is enhanced and ΔE is reduced. ST, roll-off is significantly reduced, thereby achieving a higher photoelectric conversion efficiency of OLED devices. And its synthesis does not involve precious metals, which can reduce costs. Its synthesis method is simple and easy to implement. It is easy to modify the molecular structure, and it can conveniently perform structural modification and molecular property adjustment. It also has good doping and stability. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with specific embodiments. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The embodiment of the present invention discloses a method for preparing a boron-containing fused ring compound of 2H-isoindole.

[0037] In addition, it should be noted that the numerical values ​​given in the following embodiments are as accurate as possible, but those skilled in the art understand that due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximate number rather than an absolutely accurate value.

[0038] Example 1

[0039] In this embodiment, the preparation of the above-mentioned compound 1 is involved, and the specific preparation process is as follows, and the synthetic route is as follows:

[0040]

[0041] Synthesis of intermediate 1-1:

[0042] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 2 (1.69g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 1-1 (3.44g, yield = 80%).

[0043] Synthesis of intermediate 1-2:

[0044] Take a 500mL two-necked bottle, dry it, add a stirrer, and add intermediate a1-1 (2.87g, 10.0mmol, 1.0eq.), raw material 3 (2.03g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 1-2 (2.93g, yield: 78%).

[0045] Synthesis of target compound 1:

[0046] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 1-2 (1.88g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 1 as a solid with a yield of 65% (1.25g, 3.25mmol).

[0047] Example 2

[0048] In this embodiment, the preparation of the above-mentioned compound 8 is involved, and the specific preparation process is as follows, and the synthetic route is as follows:

[0049]

[0050] Synthesis of intermediate 8-1:

[0051] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 4 (1.71g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The composite organic layer is dried with anhydrous Na2SO4. Purification by column chromatography gives intermediate 8-1 (3.02g, yield = 70%).

[0052] Synthesis of intermediate 8-2:

[0053] Take a 500mL two-necked bottle, dry it, add a stirrer, and add intermediate 8-1 (2.88g, 10.0mmol, 1.0eq.), raw material 5 (2.04g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 8-2 (2.95g, yield: 78%).

[0054] Synthesis of target compound 8:

[0055] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 8-2 (1.89g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 8 as a solid with a yield of 62% (1.20g, 3.10mmol).

[0056] Example 3

[0057] In this embodiment, the preparation of the above-mentioned compound 10 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0058]

[0059] Synthesis of intermediate 10-1:

[0060] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 6 (2.59g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 10-1 (3.29g, yield = 65%).

[0061] Synthesis of intermediate 10-2:

[0062] Take a 500mL two-necked bottle, dry it, add a stirrer, and add intermediate 10-1 (3.37g, 10.0mmol, 1.0eq.), raw material 7 (2.04g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 10-2 (3.92g, yield: 82%).

[0063] Synthesis of target compound 10:

[0064] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load the intermediate 10-2 (1.88g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 10 as a solid with a yield of 66% (1.60g, 3.3mmol).

[0065] Example 4

[0066] In this embodiment, the preparation of the above-mentioned compound 16 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0067]

[0068] Synthesis of intermediate 16-1:

[0069] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 8 (4.07g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 16-1 (3.90g, yield = 62%).

[0070] Synthesis of intermediate 16-2:

[0071] Take a 500mL two-necked bottle, dry it, add a stirrer, and add intermediate 16-1 (4.19g, 10.0mmol, 1.0eq.), raw material 3 (2.03g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 16-2 (4.06g, yield: 80%).

[0072] Synthesis of target compound 16:

[0073] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 16-2 (2.54g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 16 as a solid with a yield of 56% (1.44g, 2.8mmol).

[0074] Example 5

[0075] In this embodiment, the preparation of the above-mentioned compound 21 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0076]

[0077] Synthesis of intermediate 21-1:

[0078] Take a 250mL reaction bottle, dry it, add a stirrer, and then dissolve the raw material 9 (1.46g, 10.0mmol, 1.0eq.) and the raw material 10 (0.93g, 10.0mmol, 1.0eq.) in 50mL toluene solution. Under nitrogen atmosphere, add sodium tert-butoxide (1.92g, 20.0mmol, 2.0eq.), palladium acetate (1.13g, 5.0mmol, 0.5eq.), tri-tert-butylphosphine tetrafluoroborate (1.45g, 5.0mmol, 0.5eq.). After the reaction system is refluxed for 72 hours, it is cooled to room temperature. The solvent is removed by rotary evaporation, and the residue is extracted with dichloromethane (3×100mL). The organic phase is washed with water and dried with sodium sulfate. The solvent is removed by vacuum distillation, and the obtained crude product is separated and purified by silica gel chromatography column, eluent: dichloromethane: petroleum ether = 1:4, to obtain the intermediate product 21-1.

[0079] Synthesis of intermediate 21-2:

[0080] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 11 (1.51g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The composite organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 21-2 (2.49g, yield = 60%).

[0081] Synthesis of intermediate 21-3:

[0082] Take a 500mL two-necked bottle, dry it, add a stirrer, add intermediate 21-2 (2.77g, 10.0mmol, 1.0eq.), intermediate 21-1 (1.91g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 21-3 (2.85g, yield: 80%).

[0083] Synthesis of target compound 21:

[0084] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 21-3 (1.78g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 21 as a solid with a yield of 54% (0.99g, 2.7mmol).

[0085] Example 6

[0086] In this embodiment, the preparation of the above-mentioned compound 38 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0087]

[0088] Synthesis of intermediate 38-1:

[0089] Take a 250mL reaction bottle, dry it, add a stirrer, and then dissolve the raw material 12 (1.61g, 10.0mmol, 1.0eq.) and the raw material 10 (0.93g, 10.0mmol, 1.0eq.) in 50mL toluene solution. Under nitrogen atmosphere, add sodium tert-butoxide (1.92g, 20.0mmol, 2.0eq.), palladium acetate (1.13g, 5.0mmol, 0.5eq.), tri-tert-butylphosphine tetrafluoroborate (1.45g, 5.0mmol, 0.5eq.). After the reaction system is refluxed for 72 hours, it is cooled to room temperature. The solvent is removed by rotary evaporation, and the residue is extracted with dichloromethane (3×100mL). The organic phase is washed with water and dried with sodium sulfate. The solvent is removed by vacuum distillation, and the resulting crude product is separated and purified by silica gel chromatography, eluent: dichloromethane: petroleum ether = 1:4, to obtain the intermediate product 38-1.

[0090] Synthesis of intermediate 38-2:

[0091] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 13 (2.61g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 38-2 (3.30g, yield = 65%).

[0092] Synthesis of intermediate 38-3:

[0093] Take a 500mL two-necked bottle, dry it, add a stirrer, add intermediate 38-2 (3.38g, 10.0mmol, 1.0eq.), intermediate 38-1 (2.10g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tris(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 38-3 (3.55g, yield: 82%).

[0094] Synthesis of target compound 38:

[0095] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 38-3 (2.17g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 38 as a solid with a yield of 59% (1.30g, 2.95mmol).

[0096] Example 7

[0097] In this embodiment, the preparation of the above-mentioned compound 39 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0098]

[0099] Synthesis of intermediate 39-1:

[0100] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 2 (1.69g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 39-1 (2.93g, yield = 68%).

[0101] Synthesis of intermediate 39-2:

[0102] Take a 500mL two-necked bottle, dry it, add a stirrer, and add intermediate 39-1 (2.87g, 10.0mmol, 1.0eq.), raw material 14 (2.00g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tri(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 39-2 (3.29g, yield: 88%).

[0103] Synthesis of target compound 39:

[0104] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 39-2 (1.87g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 38 as a solid with a yield of 65% (1.24g, 3.25mmol).

[0105] Example 8

[0106] In this embodiment, the preparation of the above-mentioned compound 69 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0107]

[0108] Synthesis of intermediate 69-1:

[0109] Take a 250mL reaction bottle, dry it, add a stirrer, and then dissolve the raw material 15 (2.12g, 10.0mmol, 1.0eq.) and the raw material 10 (0.93g, 10.0mmol, 1.0eq.) in 50mL toluene solution. Under nitrogen atmosphere, add sodium tert-butoxide (1.92g, 20.0mmol, 2.0eq.), palladium acetate (1.13g, 5.0mmol, 0.5eq.), tri-tert-butylphosphine tetrafluoroborate (1.45g, 5.0mmol, 0.5eq.). After the reaction system is refluxed for 72 hours, it is cooled to room temperature. The solvent is removed by rotary evaporation, and the residue is extracted with dichloromethane (3×100mL). The organic phase is washed with water and dried with sodium sulfate. The solvent is removed by vacuum distillation, and the obtained crude product is separated and purified by silica gel chromatography column, eluent: dichloromethane: petroleum ether = 1:4, to obtain the intermediate product 69-1.

[0110] Synthesis of intermediate 69-2:

[0111] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 16 (2.70g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 69-2 (4.12g, yield = 80%).

[0112] Synthesis of intermediate 69-3:

[0113] Take a 500mL two-necked bottle, dry it, add a stirrer, add intermediate 69-2 (3.43g, 10.0mmol, 1.0eq.), intermediate 69-1 (2.70g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tris(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 69-3 (3.55g, yield: 82%).

[0114] Synthesis of target compound 69:

[0115] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 69-3 (1.13g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, o-dichlorobenzene was evaporated under reduced pressure. The residue was collected and purified by silica gel column chromatography (eluent: petroleum ether) and recrystallization from hexane to obtain the target product compound 69 as a solid with a yield of 64% (1.59g, 3.2mmol).

[0116] Example 9

[0117] In this embodiment, the preparation of the above-mentioned compound 71 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0118]

[0119] Synthesis of intermediate 71-1:

[0120] Take a 250mL reaction bottle, dry it, add a stirrer, and then dissolve the raw material 12 (1.62g, 10.0mmol, 1.0eq.) and the raw material 10 (0.93g, 10.0mmol, 1.0eq.) in 50mL toluene solution. Under nitrogen atmosphere, add sodium tert-butoxide (1.92g, 20.0mmol, 2.0eq.), palladium acetate (1.13g, 5.0mmol, 0.5eq.), tri-tert-butylphosphine tetrafluoroborate (1.45g, 5.0mmol, 0.5eq.). After the reaction system is refluxed for 72 hours, it is cooled to room temperature. The solvent is removed by rotary evaporation, and the residue is extracted with dichloromethane (3×100mL). The organic phase is washed with water and dried with sodium sulfate. The solvent is removed by vacuum distillation, and the resulting crude product is separated and purified by silica gel chromatography, eluent: dichloromethane: petroleum ether = 1:4, to obtain the intermediate product 71-1.

[0121] Synthesis of intermediate 71-2:

[0122] Take a 500mL reaction bottle, dry it and add a stirrer, then weigh raw material 1 (5.24g, 15.0mmol, 1.0eq.), raw material 17 (2.41g, 18.0mmol, 1.2eq.) and cesium carbonate (19.5g, 60.0mmol, 4.0eq.), then add 150mL of anhydrous and oxygen-free solvent N,N-dimethylformamide, mix well and stir the mixture at 150°C for 12h, cool to room temperature and add water, and extract the water layer with ethyl acetate. The combined organic matter is washed with water and evaporated under reduced pressure to obtain a crude product. The combined organic layer is dried over anhydrous Na2SO4. Purification by column chromatography gives intermediate 71-2 (3.43g, yield = 70%).

[0123] Synthesis of intermediate 71-3:

[0124] Take a 500mL two-necked bottle, dry it, add a stirrer, add intermediate 71-2 (3.27g, 10.0mmol, 1.0eq.), intermediate 71-1 (2.10g, 12.0mmol, 1.2eq.), cesium carbonate (13.00g, 40.0mmol, 4.0eq.), tris(dibenzylideneacetone)dipalladium (9.2g, 1.0mmol, 0.1eq.), tri-tert-butylphosphine (2.00g, 1mmol, 0.1eq.) and 300mL of o-xylene. Under nitrogen protection, heat in an oil bath at 130℃ for 12 hours to stop the reaction, pour the reaction mixture into distilled water, extract with dichloromethane, concentrate, and separate with dichloromethane and petroleum ether as developing agent by column chromatography to obtain intermediate 71-3 (3.38g, yield: 80%).

[0125] Synthesis of target compound 71:

[0126] Take a 500mL reaction bottle, dry it, add a stirrer, connect a nitrogen device, and under nitrogen protection, load intermediate 71-3 (2.11g, 5.0mmol, 1.0eq.), o-dichlorobenzene (40mL), boron tribromide (3.10mL, 30.0mmol, 6.0eq.) and N, N-diisopropylethylamine (6.00mL, 30.0mmol, 6.0eq.) into a sealed tube. Heat the reaction mixture to 180°C for 24 hours. After cooling to room temperature, evaporate the solvent under reduced pressure. Collect the residue and purify it by silica gel column chromatography (eluent: petroleum ether) and hexane recrystallization to obtain the target product compound 71 as a solid with a yield of 68% (1.46g, 3.4mmol).

[0127] The synthesis methods of other compounds are the same as those in the above embodiments and are not described in detail here.

[0128] Device Example 1: Preparation of an organic electroluminescent device OLED-1 containing compound 1

[0129] a. ITO anode: First, ultrasonically clean the ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 50nm with a detergent prepared in a certain proportion for 15 minutes, then ultrasonically clean the substrate in ultrapure deionized water for 10 minutes, and finally ultrasonically clean it with acetone, anhydrous ethanol and deionized water for 5 minutes respectively. The cleaned substrate is placed in a 120℃ forced air drying oven for 1 hour. Oxygen plasma treatment can further clean the surface of the substrate and on the other hand, it can effectively remove the surface of the ITO

[0130] b. The surface work function plays a regulatory role, so that the potential barrier between it and the organic layer is reduced, which is conducive to the injection of holes. It can effectively reduce the driving voltage of the device. The specific operation method is to place the substrate in a vacuum chamber, wait for the vacuum degree of the chamber to be less than 10Pa, pass oxygen into the chamber for 5 minutes, wait for the air pressure to stabilize, turn on the RF power switch, and discharge the pure oxygen chamber at a frequency of 150Hz for 30 seconds. After the end, N2 is passed into the chamber, and the substrate is taken out and transferred to the chamber of the vacuum evaporation equipment to evaporate other functional layers on it in sequence.

[0131] b. HIL (hole injection layer): TAPC was vacuum-deposited at a deposition rate of 0.2 nm / s to a thickness of 50 nm.

[0132] c. HTL (hole transport layer): 5 nm of TCTA was vacuum-deposited on the hole injection layer at a deposition rate of 0.1 nm / s as the hole transport layer;

[0133] d. EML (light-emitting layer): The materials of the light-emitting layer are compound 1 and InCz23DMeTz, with a mass ratio of 5:100 and a deposition rate ratio of 1:100. On the above-mentioned light-emitting auxiliary layer, compound 1 and m-CBP (mass ratio: 5:100) with a thickness of 40 nm were vacuum-deposited at a deposition rate of 0.2 nm / s as the light-emitting layer.

[0134] e. ETL (electron transport layer): 25 nm TmPyPB was vacuum-deposited on the light-emitting layer at a deposition rate of 0.1 nm / s as an electron transport layer;

[0135] f. EIL (electron injection layer): Liql was evaporated to a thickness of 15 nm at a deposition rate of 0.5 nm / s to form an electron injection layer;

[0136] g. Cathode: The magnesium / silver alloy layer is used as the cathode layer of the device. The mass ratio of magnesium to silver is 1:9. 90 nm is evaporated at an evaporation rate ratio of 1.0 to 2.0 nm / s to obtain the device OLED-1.

[0137] The structural formula of the materials used is shown below:

[0138]

[0139] Device Examples 2-20 refer to the above method, and replace the compound 1 used in device Example 1 with compounds 5, 10, 16, 21, 28, 39, 42, 47, 51, 57, 60, 63, 75, 82, 95, 104, 109, 116, and 120 as the light-emitting layer doping material to prepare the corresponding organic electroluminescent devices OLED-2 to OLED-20.

[0140] Device Comparative Examples 1 to 3: This comparative example provides an organic electroluminescent device. The only difference between the preparation method of the organic electroluminescent device and the device embodiment is that the organic electroluminescent device uses existing comparative compounds α, β, and γ to replace the light-emitting layer (compound 1) in the above device embodiment 1 for evaporation, and prepares device comparative examples 1 to 3: devices OLED-a, OLED-b, and OLED-c. Among them, the chemical structural formulas of comparative compounds a, b, and c are:

[0141]

[0142] The driving voltage, luminous efficiency, FWHM and color of the organic electroluminescent devices obtained from the device embodiments 1 to 20 and the device comparative examples 1 to 3 were characterized at a brightness of 1000 (nits). The test results are shown in Table 1 below:

[0143] Table 2 Driving voltage, luminous efficiency, FWHM and color of the organic electroluminescent devices of device examples 1-20

[0144]

[0145]

[0146] It can be seen from the above table that the organic electroluminescent device prepared by using the boron-containing fused ring compound of 2H-isoindole provided by the present invention as the luminescent material has a lower starting voltage, and its luminous efficiency and color purity are significantly improved.

[0147] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined in the present invention may be implemented in other embodiments without departing from the concept or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown in the present invention, but rather to the widest range consistent with the principles and novel features disclosed in the present invention.

Claims

1. A boron-containing fused ring compound organic electroluminescent material based on 2H-isoindole, characterized in that: The organic electroluminescent material has the following design main body, and its design general formula is shown in the figure: Wherein n1 and n2 are each independently an integer greater than or equal to 1; wherein ring Ar1 and ring Ar2 are the same or different and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heteroaromatic ring, a substituted or unsubstituted five-membered aromatic heterocycle, or a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered aromatic heterocycle, and a five-membered aromatic heterocycle, and the aromatic condensed ring unit is connected to B, N, O, or S via a six-membered aromatic ring, a six-membered aromatic heterocycle, or a five-membered aromatic heterocycle; wherein R1, R2, R3 and R4 are each independently selected from H, F, Cl, Br, I, -CN, O-R6, -S-R6, -Se-R6, A substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, a substituted or unsubstituted C5-C60 heteroaromatic group; The R6, R7 and R8 are each independently selected from H, F, Cl, Br, I, -OH, -SH, -NH2, a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, a substituted or unsubstituted C5-C60 heteroaromatic group; the heteroatoms in the heteroaromatic group are selected from one or more of Si, N, P, O, S and Se.

2. The 2H-isoindole-based boron-containing fused ring compound organic electroluminescent material according to claim 1, characterized in that: The structure 2H-isoindole is introduced into the design main body to replace the six-membered ring in the traditional MR-TADF skeleton; based on the design main body, different groups are linked to give different material properties.

3. The 2H-isoindole-based boron-containing fused ring compound organic electroluminescent material according to claim 1, characterized in that: The luminescent material is selected from any one of the following compounds:

4. An application of a boron-containing fused ring compound of 2H-isoindole as claimed in any one of claims 1 to 3 in an organic electroluminescent material, characterized in that: The 2H-isoindole boron-containing fused ring compound organic electroluminescent material can be used in organic electroluminescent devices.

5. The use of the boron-containing fused ring compound of 2H-isoindole according to claim 4 in an organic electroluminescent material, characterized in that: The organic electroluminescent device comprises a first electrode, a second electrode, and one or more organic layers disposed between the first electrode and the second electrode; and the organic layers comprise one of a hole injection layer, a hole transport layer, an electron blocking layer, a luminescence auxiliary layer, a luminescent layer, a hole blocking layer, an electron transport layer and an electron injection layer; and the hole transport layer comprises the 2H-isoindole-containing boron-containing fused ring compound organic electroluminescent material.

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