Organic light-emitting material with mr-tadf property and bnf system and synthesis method thereof

Abstract

The application provides a BNF system organic luminescent material with MR-TADF properties and a synthesis method thereof. The molecule is integrated by fluorobenzene, and has high symmetry; and the method constructs the BNF system organic luminescent material through a palladium catalyzed hydrogen activation method. The application uses 2,5-dibromo-1,3-difluorobenzene and 3,6-di-tert-butyl carbazole as raw materials to synthesize a small molecule system required in the first step, obtains an organic luminescent small molecule through one-pot B insertion, and effectively synthesizes four different MR-TADF organic fluorescent materials through a commercially available palladium catalyst, a phosphine ligand and a fluorobenzene compound in the later period. The raw material utilization rate of the method is high, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic functional materials technology, specifically relating to a BNF organic light-emitting material with MR-TADF properties and its preparation method. Background Technology

[0002] Achieving high color purity and a small full width at half maximum (FWHM) remains a core objective in the development of high-resolution displays. Although narrow-band luminescent materials with multi-resonance induced thermally activated delayed fluorescence (MR-TADF) have been widely used in the blue light region, their potential in other color gamuts has not been fully validated. This study aims to enhance MR-TADF by optimizing the framework structure and the interaction mechanism of peripheral units, or by integrating multiple luminescent units. By preparing BNF-based MR-TADF organic luminescent materials, peripheral units with electronic defect characteristics can significantly reduce the bandgap required for color-changing emission without sacrificing color fidelity. The developed MR-TADF luminescent materials exhibit high quantum yield, a narrow FWHM, and excellent long-term stability.

[0003] Hydrocarbon activation reactions, as a highly efficient construction strategy in organic synthesis, are widely used in many fields such as functional materials and drug synthesis. By precisely activating inert CH bonds, scientists can directly and efficiently construct complex organic functional molecules with diverse structures without pre-functionalization, greatly simplifying synthetic routes and promoting the innovative development of modern organic synthetic chemistry and advanced materials chemistry. Transition metal catalysts and suitable ligands play a central role in the efficient and highly selective conduct of hydrocarbon activation reactions. The classic catalytic system composed of palladium-based catalysts and phosphine ligands is one of the most widely used catalytic systems in the field of hydrocarbon activation. Due to its excellent reactivity, chemoselectivity, and broad substrate compatibility, it is widely used in the synthesis of functional molecules and materials modification research. Summary of the Invention

[0004] The purpose of this invention is to synthesize a series of BNF-based MR-TADF organic luminescent materials through carbon-hydrogen bond activation. This unique rigid aromatic framework suppresses molecular vibrations and rotations, reduces structural relaxation in excited states, and achieves high fluorescence quantum yield and narrow half-maximum width at half-maximum (HWHM). Furthermore, the synthesis method is relatively simple and the molecular structure is easily modified. By incorporating small molecule luminescent units onto fluorobenzene, four luminescent materials—3F-1BN, 3F-2BN, 3F-3BN, and 4F-1BN—were synthesized.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] This invention provides an organic light-emitting material of BNF system with MR-TADF properties, which includes compound 3F-1BN, compound 3F-2BN, compound 3F-3BN, and compound 4F-IBN;

[0007] The chemical structural formula of the compound 3F-1BN is as follows:

[0008]

[0009] The chemical structural formula of the compound 3F-2BN is as follows:

[0010]

[0011] The chemical structural formula of the compound 3F-3BN is as follows:

[0012]

[0013] The chemical structural formula of the compound 4F-1BN is as follows:

[0014]

[0015] The present invention also provides a method for preparing the above-mentioned organic light-emitting material of BNF system with MR-TADF properties. The method includes: generating intermediate 1 by carbon-nitrogen coupling reaction, then preparing intermediate BCzBNBr 2 by stepwise arylboration and high-temperature intramolecular cyclization reaction mediated by organolithium, and finally preparing the final organic light-emitting material of BNF system with MR-TADF by carbon-hydrogen bond activation method.

[0016] Furthermore, the method includes the following specific steps:

[0017] (1) Synthesis of intermediate 1: 2,5-Dibromo-1,3-difluorobenzene was added to a mixture of N-methylpyrrolidone (NMP) containing 3,6-di-tert-butylcarbazole and cesium carbonate under an argon atmosphere, and then the mixture was stirred at 100°C for 12 hours. After cooling to room temperature, the mixture was poured into water and stirred for 10 minutes. After filtration, the solid was washed successively with water and ethanol to obtain a white solid precursor, which is compound DCzBNBr.

[0018] The structural formula of the compound DCzBNBr is as follows:

[0019]

[0020] (2) Synthesis of Intermediate 2: Under an argon atmosphere, 2.4 M n-butyllithium was dissolved in hexane and added to an ultra-dry trimethylbenzene solution containing Intermediate 1. After stirring at room temperature for 2 hours, boron tribromide was added, and stirring was continued at room temperature for another 2 hours. Subsequently, N,N-diisopropylethylamine was added, the reaction temperature was raised to 140°C, and stirring was carried out for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, water was added, and the mixture was stirred for 10 minutes, followed by the addition of petroleum ether. After filtering the mixture, the solid was washed successively with water, ethanol, and petroleum ether to obtain a yellow solid. The obtained intermediate 2 is compound BCzBNBr;

[0021] The structural formula of the compound BCzBNBr is as follows:

[0022]

[0023] (3) Synthesis of compounds 3F-1BN, 3F-2BN, 3F-3BN, or 4F-1BN: Under a nitrogen atmosphere, the above intermediates 2, 1,3,5-trifluorobenzene or 1,2,4,5-tetrafluorobenzene, palladium acetate or palladium neopentanoate, cyclohexylphosphine tetrafluoroborate, and cesium carbonate were added to a flask containing degassed toluene. The reaction was stirred at 130°C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The diluted solvent was then dried with sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to obtain the corresponding products 3F-1BN, 3F-2BN, 3F-3BN, or 4F-4BN.

[0024] Furthermore, in step (1), the molar ratio of 2,5-dibromo-1,3-difluorobenzene and 3,6-di-tert-butylcarbazole is 1:2.1, and the reaction temperature is 100℃.

[0025] Furthermore, in step (2), the molar ratio of intermediate 1, n-butyllithium, boron tribromide and N,N-diisopropylethylamine is 1:1.1:2:2.

[0026] Furthermore, in step (2), before the reaction is carried out under argon protection, oxygen is removed and then argon is added, and this process is repeated three times.

[0027] Furthermore, the addition of n-butyllithium, boron tribromide and N,N-diisopropylethylamine in step (2) is all performed at 0°C.

[0028] Furthermore, the required palladium catalyst in step (3) has a mass fraction of 5 wt%.

[0029] Furthermore, the required phosphine ligand mass fraction in step 3) is 10 wt%.

[0030] Furthermore, in step (3), the ratio of intermediate 2 to fluorobenzene is 2:1.

[0031] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects:

[0032] (1) Intermediate 1 is obtained by carbon-nitrogen coupling, and then BCzBNBr intermediate 2 is prepared by stepwise arylboration and high-temperature intramolecular cyclization mediated by organolithium. This method only requires two simple organic reactions to obtain the key intermediate of the target molecule and is extremely efficient.

[0033] (2) The final product can simultaneously obtain 2-3 target molecules through hydrocarbon activation, with high raw material utilization and simple method.

[0034] (3) By enhancing the interaction between the skeleton structure and the peripheral unit, the peripheral unit with electronic defect characteristics can significantly reduce the band gap required for color reduction luminescence without sacrificing color fidelity.

[0035] (4) By integrating multiple luminescent units, the aim is to improve the solution processing performance and luminescence efficiency of multi-resonance induced thermally activated delayed fluorescence (Mr-TADF) materials. Attached Figure Description

[0036] Figure 1 It is the compound DCzBNBr prepared in Example 1 of this invention. 1 H-NMR spectrum;

[0037] Figure 2 It is the compound BCzBNBr prepared in Example 1 of this invention. 1 H-NMR spectrum;

[0038] Figure 3 It is the compound 3F-1BN prepared in Example 2 of this invention. 1 H-NMR spectrum;

[0039] Figure 4 It is the compound 3F-1BN prepared in Example 2 of this invention. 19 F-NMR spectrum;

[0040] Figure 5 It is the compound 3F-2BN prepared in Example 2 of this invention. 1 H-NMR spectrum;

[0041] Figure 6 It is the compound 3F-2BN prepared in Example 2 of this invention. 19 F-NMR spectrum;

[0042] Figure 7It is the compound 3F-3BN prepared in Example 2 of this invention. 1 H-NMR spectrum;

[0043] Figure 8 It is the compound 3F-3BN prepared in Example 2 of this invention. 19 F-NMR spectrum;

[0044] Figure 9 It is the compound 4F-1BN prepared in Example 3 of this invention. 1 H-NMR spectrum;

[0045] Figure 10 It is the compound 4F-1BN prepared in Example 3 of this invention. 19 F-NMR spectrum; Detailed Implementation

[0046] The present invention will now be described in detail with reference to specific embodiments.

[0047] Example 1

[0048] A. Synthesis of compound DCzBNBr:

[0049] To a 20 mL mixture of N-methylpyrrolidone (NMP) containing 3,6-di-tert-butylcarbazole (5.3 g, 18.9 mmol) and cesium carbonate (6.6 g, 20 mmol), 2,5-dibromo-1,3-difluorobenzene (2.4 g, 9 mmol) was added under an argon atmosphere, followed by stirring at 100 °C for 12 h. After cooling to room temperature, the mixture was poured into water and stirred for 10 min. The mixture was filtered, and the solid was washed with water and ethanol to give a white solid intermediate 1DCzBNBr (5.9 g, 84% yield).

[0050] The equations involved in this implementation are as follows:

[0051]

[0052] B. Synthesis of compound BCzBNBr:

[0053] Under an argon atmosphere, 2.4 M n-butyllithium (2.3 mL, 5.5 mmol) was dissolved in hexane and added to 20 mL of ultra-dry trimethylbenzene solution containing DCzBNBr (5 mmol). The reaction temperature was 0 °C. After stirring at room temperature for 2 hours, boron tribromide (0.96 mL, 10 mmol) was added at 0 °C, and stirring was continued at room temperature for another 2 hours. Subsequently, N,N-diisopropylethylamine (1.66 mL, 10 mmol) was added at 0 °C, and the reaction temperature was raised to 140 °C and stirred for 24 hours. After cooling to room temperature, 10 mL of water was added and stirred for 10 minutes, followed by the addition of 50 mL of petroleum ether. After filtering the mixture, the solid was washed successively with water, ethanol, and petroleum ether to give 2.9 g of a yellow solid, with a yield of 82%.

[0054] The equations involved in this implementation are as follows:

[0055]

[0056] Example 2

[0057] A. Synthesis of compound 3F-1BN:

[0058] Under a nitrogen atmosphere, intermediate 2 (1.4 g, 2 mmol), 1,3,5-trifluorobenzene (0.13 g, 1 mmol), palladium acetate (15.5 mg, 5 mol%), cyclohexylphosphine tetrafluoroborate (37 mg, 10 mol%), and cesium carbonate (1.3 g, 4 mmol) were added to a flask containing degassed toluene. The reaction was stirred at 130 °C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The solvent was then dried over sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give the corresponding product 3F-1BN (84 mg, 11% yield).

[0059] The equations involved in this implementation are as follows:

[0060]

[0061] B. Synthesis of compound 3F-2BN:

[0062] Under a nitrogen atmosphere, intermediate 2 (1.4 g, 2 mmol), 1,3,5-trifluorobenzene (0.13 g, 1 mmol), palladium acetate (15.5 mg, 5 mol%), cyclohexylphosphine tetrafluoroborate (37 mg, 10 mol%), and cesium carbonate (1.3 g, 4 mmol) were added to a flask containing degassed toluene. The reaction was stirred at 130 °C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The solvent was then dried over sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give the corresponding product 3F-2BN (169 mg, 12% yield).

[0063] The equations involved in this implementation are as follows:

[0064]

[0065] C. Synthesis of compound 3F-3BN:

[0066] Under a nitrogen atmosphere, intermediate 2 (2.1 g, 3 mmol), 1,3,5-trifluorobenzene (0.13 g, 1 mmol), palladium neopentanoate (15 mg, 5 mol%), cyclohexylphosphine tetrafluoroborate (37 mg, 10 mol%), and cesium carbonate (1.3 g, 4 mmol) were added to a flask containing degassed toluene. The reaction was stirred at 130 °C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The solvent was then dried over sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give the corresponding product 3F-3BN (696 mg, 34% yield).

[0067] The equations involved in this implementation are as follows:

[0068]

[0069] Example 3

[0070] Synthesis of compound 4F-1BN:

[0071] Under a nitrogen atmosphere, intermediate 2 (1.4 g, 2 mmol), 2,3,4,5-tetrafluorobenzene (0.15 g, 1 mmol), palladium acetate (15 mg, 5 mol%), cyclohexylphosphine tetrafluoroborate (37 mg, 10 mol%), and cesium carbonate (1.3 g, 4 mmol) were added to a flask containing degassed toluene. The reaction was stirred at 130 °C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The solvent was then dried over sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give the corresponding product 4F-1BN (323 mg, 41% yield).

[0072] The equations involved in this implementation are as follows:

[0073]

[0074] In summary, this invention synthesizes a series of BNF-based organic fluorescent compounds with MR-TADF properties. The MR-TADF characteristics of these molecules are modulated by integrating small molecule luminescent units with fluorobenzene. The four different MR-TADF organic fluorescent materials synthesized in this invention exhibit excellent solubility and tunable luminescence properties, and can be used for solution-based fabrication of organic light-emitting diodes.

[0075] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the present invention. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A BNF system organic light-emitting material with MR-TADF properties, characterized in that, The organic light-emitting materials of the BNF system with MR-TADF properties include compounds 3F-1BN, 3F-2BN, 3F-3BN, and 4F-1BN; The chemical formula of the compound 3F-1BN is as follows: The chemical structural formula of the compound 3F-2BN is as follows: The chemical structural formula of the compound 3F-3BN is as follows: The structural formula of the compound 4F-1BN is as follows:

2. A method for preparing a BNF system organic light-emitting material with MR-TADF properties according to claim 1, characterized in that, The method includes: firstly, synthesizing DCzBNBr intermediate 1 through carbon-nitrogen coupling; secondly, preparing BCzBNBr intermediate 2 through stepwise arylboration and high-temperature intramolecular cyclization reactions mediated by organolithium; and finally preparing the final MR-TADF BNF system organic light-emitting material through carbon-hydrogen bond activation.

3. The method for preparing organic light-emitting molecules with MR-TADF BNF system according to claim 2, characterized in that, The method includes the following specific steps: (1) Synthesis of intermediate 1: 2,5-Dibromo-1,3-difluorobenzene was added to a mixture of N-methylpyrrolidone (NMP) containing 3,6-di-tert-butylcarbazole and cesium carbonate under an argon atmosphere, and then the mixture was stirred at 100°C for 12 hours. After cooling to room temperature, the mixture was poured into water and stirred for 10 minutes. After filtration, the solid was washed successively with water and ethanol to obtain a white solid precursor, which is compound DCzBNBr. The structural formula of the compound DCzBNBr is as follows: (2) Synthesis of Intermediate 2: Under an argon atmosphere, 2.4 M n-butyllithium was dissolved in hexane and added to an ultra-dry trimethylbenzene solution containing Intermediate 1. After stirring at room temperature for 2 hours, boron tribromide was added, and stirring was continued at room temperature for another 2 hours. Subsequently, N,N-diisopropylethylamine was added, the reaction temperature was raised to 140°C, and stirring was carried out for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, water was added, and the mixture was stirred for 10 minutes, followed by the addition of petroleum ether. After filtering the mixture, the solid was washed successively with water, ethanol, and petroleum ether to obtain a yellow solid. The obtained intermediate 2 is compound BCzBNBr; The structural formula of the compound BCzBNBr is as follows: (3) Synthesis of compounds 3F-1BN, 3F-2BN, 3F-3BN, or 4F-1BN: Under a nitrogen atmosphere, the above intermediates 2, 1,3,5-trifluorobenzene or 1,2,4,5-tetrafluorobenzene, palladium acetate or palladium neopentanoate, cyclohexylphosphine tetrafluoroborate, and cesium carbonate were added to a flask containing degassed toluene. The reaction was stirred at 130°C for 24 hours. After cooling to room temperature, the mixture was diluted with dichloromethane and washed with water. The diluted solvent was then dried with sodium sulfate and removed by rotary evaporation. The crude product was purified by silica gel column chromatography to obtain the corresponding products 3F-1BN, 3F-2BN, 3F-3BN, or 4F-4BN.

4. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, In step (1), the molar ratio of 2,5-dibromo-1,3-difluorobenzene and 3,6-di-tert-butylcarbazole is 1:2.1, and the reaction temperature is 100℃.

5. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, In step (2), the molar ratio of intermediate 1, n-butyllithium, boron tribromide and N,N-diisopropylethylamine is 1:1-1:2:

2.

6. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, In step (2), before the reaction is carried out under argon protection, oxygen is removed and then argon is added, and this process is repeated three times.

7. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, In step (2), the addition of n-butyllithium, boron tribromide and N,N-diisopropylethylamine is all carried out at 0°C.

8. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, The required palladium catalyst mass fraction in step (3) is 5 wt%.

9. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, The required phosphine ligand mass fraction in step 3) is 10 wt%.

10. The method for preparing BNF organic light-emitting material with MR-TADF according to claim 3, characterized in that, In step (3), the ratio of intermediate 2 to fluorobenzene is 2:1.

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