The invention relates to a 9, 9apos derivative containing pyridine heterocycle. Spirobifluorenyl organic luminescent material and application thereof

Abstract

The invention provides a 9, 9 '-spirobifluorenyl organic light-emitting material containing pyridine heterocycle and application thereof, and belongs to the field of organic light-emitting materials. The 9, 9 '-spirobifluorenyl organic light-emitting material containing pyridine heterocycle can observe the emission of blue light with the wavelength of 375-425 nm under the excitation of 341 nm ultraviolet light, has good thermal stability and solubility, can be used as a novel blue light-emitting material with good performance and simple synthesis method, and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the field of organic light-emitting materials, and particularly to a 9,9'-spirobifluorene-based organic light-emitting material containing a pyridine heterocycle and its application. Background Art

[0002] In recent years, the application of organic light-emitting materials in optoelectronic devices has attracted much attention. The core lies in that the material design needs to balance high efficiency, high stability, and tunable optoelectronic properties. Among them, 9,9'-spirobifluorene (SBF) has become an ideal backbone for constructing high-performance light-emitting host materials due to its unique rigid three-dimensional structure, excellent thermal stability, and chemical stability. However, traditional spirobifluorene-based materials still have limitations in carrier transport ability, luminescence efficiency, etc. Especially in the field of blue light materials, their energy level matching and exciton utilization efficiency still need to be further optimized.

[0003] To break through the above bottlenecks, the introduction of heterocyclic structures has become an important molecular engineering strategy. The pyridine heterocycle is often used to improve the charge injection and transport balance of materials due to its strong electron affinity, tunable energy level structure, and excellent electron transport characteristics. Combining the pyridine unit with the spirobifluorene backbone is expected to optimize the energy level distribution of the material through intramolecular synergistic effects, enhance the luminescence performance, and maintain its inherent stability. Summary of the Invention

[0004] Aiming at the above deficiencies of existing materials, the present invention provides a 9,9'-spirobifluorene-based organic light-emitting material containing a pyridine heterocycle. A series of novel derivatives containing a pyridine heterocycle are designed and synthesized, and the structure-activity relationship between the molecular structure and properties is explored by regulating the types of substituents. The material structure is characterized by means of nuclear magnetic resonance (NMR), mass spectrometry (MS), etc., and its fluorescence excitation spectrum, emission spectrum, and thermogravimetric analysis (TGA) performance are systematically tested. The research aims to provide a theoretical basis for the development of efficient and stable blue light materials.

[0005] Compound of formula I:

[0006]

[0007] Wherein, R is R a is or

[0008] For some specific compounds, each X independently is an alkyl group with 1 to 12 carbon atoms.

[0009] For some specific compounds, R a is

[0010] For some specific compounds, R a is

[0011] For some specific compounds, X is independently an alkyl group having 1 to 10 carbon atoms in each case.

[0012] For some specific compounds, X is independently an alkyl group having 1 to 5 carbon atoms in each case.

[0013] For some specific compounds, X is independently methyl, ethyl, propyl, isopropyl, n-butyl.

[0014] For some specific compounds, X is independently methyl.

[0015] The preparation method of the described compound is as follows:

[0016]

[0017] The described compound is synthesized by the Suzuki coupling reaction of 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and boronic acid pinacol ester derivatives.

[0018] wherein, the definition of R a is the same as the definition in claim 1.

[0019] An organic light-emitting material, the organic light-emitting material includes one or more of the compounds described in any one of claims 1 to 3.

[0020] Specifically, the preparation method of 9,9'-spirobifluorene derivatives includes the following steps:

[0021] (1) Under a nitrogen atmosphere, a Suzuki coupling reaction is carried out between compound a and compound b to obtain compound c

[0022]

[0023] (2) [1,1'-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) and CH3COOK are slowly added during stirring to catalyze the reaction;

[0024] (3) After reacting for 12 hours, it is cooled to room temperature;

[0025] (4) Extracted 3 times with dichloromethane;

[0026] (5) Washed 3 times with saturated brine;

[0027] (6) Purified by silica gel column chromatography to obtain compound c.

[0028] A preparation method of a specific compound, where 1 eq of Br on the skeleton corresponds to 2.0 eq of phenylboronic acid ester derivative, 0.03 eq of [1,1'-bis(diphenylphosphino)ferrocene] palladium(II) dichloride catalyst, and 2.5 eq of CH3COOK.

[0029] According to an embodiment of the present invention, the use of the compound containing a pyridine ring structure as described in any one of the above, which is used in the field of organic light-emitting materials.

[0030] Advantages of the present invention

[0031] An organic light-emitting material containing a pyridine heterocycle 9,9'-spirobifluorene group is invented. Under the excitation of 341 nm ultraviolet light, blue light emission with a wavelength in the range of 375 - 425 nm can be observed, the fluorescence quantum yield is 0.47, and there is also an obvious luminescence phenomenon in its powder state under ultraviolet lamp irradiation. Due to the introduction of the pyridine-derived structure, the material also exhibits excellent thermal stability (Td = 186 °C and Tg = 195 °C) and good solubility. Description of the drawings

[0032] Figure 1 It is the H-NMR spectrum of the compound SBF-4N(Bu) in Example 5 of the present invention.

[0033] Figure 2 It is the TGA and DSC curve graphs of the compound SBF-4N(Bu) in Example 5 of the present invention.

[0034] Figure 3 It is the fluorescence excitation spectrum, emission spectrum and fluorescence quantum yield of the compound SBF-4N(Bu) in Example 5 of the present invention.

[0035] Figure 4 It is the powder luminescence graph of the compound SBF-4N(Bu) in Example 5 under natural light and ultraviolet light. Detailed implementation manners

[0036] The technical solutions of the present invention will be further described in detail below in combination with specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0037] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by known methods.

[0038] Example 1

[0039]

[0040] Specific steps: Prepared according to the published method. 4-Hydroxypyridine-2,6-dicarboxylic acid (6.00 g, 32.77 mmol, 1 eq.) and an excess of phosphorus oxychloride (10 mL) were mixed in a 50 mL round-bottom flask and heated at 90 °C for 12 hours. The excess phosphorus oxychloride was distilled off under reduced pressure, and the remaining mixture was collected by extraction with dichloromethane and rotary evaporated under reduced pressure to obtain an off-white solid. It was added to a flask containing 40 mL of dichloromethane, and then tert-butanol (12.54 mL, 131.06 mmol, 4 eq.) and 4-dimethylaminopyridine (DMAP) (640.48 mg, 5.24 mmol, 0.16 eq.) were dissolved in a mixed solution of dichloromethane (10 mL) and pyridine (3.5 mL, 42.60 mmol, 1.3 eq.) and slowly added dropwise to the flask at room temperature. Stirred at room temperature for 24 hours, and thin-layer silica gel chromatography monitoring showed that the reaction was complete. The excess tert-butanol, dichloromethane, and pyridine were removed under vacuum. The solid residue was dispersed in dichloromethane (20 mL), and the organic solution was washed with water (2 × 10 mL), dried over anhydrous sodium sulfate, and concentrated by rotary evaporation under reduced pressure to a light yellow solid, which was purified by silica gel column chromatography with an eluent of petroleum ether:ethyl acetate = 10:1 (V / V) to obtain white solid B1 (4.63 g, 14.76 mmol, yield: 45%). The product structure was identified by HRMS, HRMS [M+H] + : 314.0841.

[0041] Example 2

[0042]

[0043] The synthesis method was referred to Example 1, using A2 instead of A1. The product structure was identified by HRMS, HRMS [M+H] + : 312.1401.

[0044] Example 3

[0045]

[0046] Specific steps: Under an argon atmosphere, di-tert-butyl 4-chloropyridine-2,6-dicarboxylate (5.00 g, 15.93 mmol, 1 eq.), bis(pinacolato)diboron (6.07 g, 23.90 mmol, 1.5 eq.), potassium acetate (4.69 g, 47.80 mmol, 3 eq.), palladium(II) acetate (178.87 mg, 0.797 mmol, 0.05 eq.), and tricyclohexylphosphine (446.87 mg, 1.59 mmol, 0.1 eq.) were added to a Schlenk flask. The flask was purged with argon three times, and then 100 mL of 1,4-dioxane solution (previously deoxygenated by bubbling) was added to dissolve the reactants. The mixture was refluxed at 105 °C for 4 hours. The reaction was monitored by silica gel thin-layer chromatography until completion. After cooling to room temperature, the reaction mixture was diluted with dichloromethane, washed with saturated brine (3 × 40 mL), dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure by rotary evaporation to obtain a black solid. The black solid was diluted with dichloromethane again and preliminarily filtered through diatomaceous earth to remove some impurities. The solvent was removed under reduced pressure by rotary evaporation to obtain a yellow oily liquid, which was recrystallized from dichloromethane and petroleum ether to obtain a white solid C1 (5.00 g, 12.34 mmol, yield: 77.42%). The product structure was identified by HRMS, HRMS [M+H] + : 406.2406.

[0047] Example 4

[0048]

[0049] The synthesis method was referred to Example 3, using B2 instead of B1. The product structure was identified by HRMS, HRMS [M+H] + : 404.2642.

[0050] Example 5

[0051]

[0052] Specific steps: Under an argon atmosphere, C1 (10.0 g), 2,2′,7,7'-tetrabromo-9,9'-spirobifluorene (1.0 g, 1.58 mmol, 1 eq.), [1,1'-bis(diphenylphosphino)ferrocene] palladium dichloride (231.56 mg, 0.317 mmol, 0.2 eq.), and potassium acetate (1.86 g, 18.99 mmol, 12 eq.) were added to a Schlenk flask. The flask was purged with argon three times, and then 50 mL of a mixed solution of 1,4-dioxane:water = 10:1 (V / V) (degassed by bubbling for 30 min in advance) was added to dissolve the reactants. The mixture was refluxed at 105 °C for 12 hours. The reaction was monitored by silica gel thin-layer chromatography until completion. After the reaction solution was cooled to room temperature, it was diluted with dichloromethane and extracted. The organic solution was washed with saturated brine (3 × 40 mL). The organic phase was collected, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation under reduced pressure to obtain a gray solid crude product. The crude product was purified by silica gel column chromatography to obtain a white solid compound SBF-4N(Bu) (900 mg, yield: 40.00%). Eluent: petroleum ether:ethyl acetate:methanol = 40:10:1 (V / V). The structure of the product was identified by HRMS, HRMS [M+2Na] 2+ : 735.3146

[0053] Example 6

[0054]

[0055] The synthesis method was referred to Example 5, using C2 instead of C1. The structure of the product was identified by HRMS, HRMS [M+H] + : 1417.7787.

[0056] Example 7

[0057]

[0058] The synthesis method was referred to Example 5, using C3 instead of C1. The structure of the product was identified by HRMS, HRMS [M+H] + : 1089.2752.

[0059] The organic light-emitting material prepared in Example 5 was tested as follows

[0060] (1) Thermal property test of the SBF-4N(Bu) compound prepared in Example 5. Test instrument and model: Q600 synchronous thermogravimetric analyzer from TA Instruments, USA. Specific test parameters are as follows: under nitrogen protection, the nitrogen flow rate was set to 20 mL / min, the heating rate was set to 10 °C / min, and the test temperature was set in the range of 40 - 800 °C. The TGA and DSC curves of SBF-4N(Bu) are as Figure 2As shown. It can be seen from the TGA curve that the weight change of SBF-4N(Bu) is small (<5%) before 186 °C, and its weight loss may be due to the volatilization of adsorbed moisture or residual solvents. After 186 °C, rapid weight loss begins until the first inflection point appears at 200 °C, at which time the weight loss rate reaches 35%. The weight loss in this stage is mainly due to the thermal decomposition of the tert-butyl ester groups on SBF-4N(Bu). Thereafter, there is another rapid weight loss process until the temperature rises to 275 °C to reach the first weight loss plateau. The weight loss in this stage is mainly due to the rapid shedding of the carboxyl groups remaining on the skeleton, and the weight loss rate reaches 57%, which is consistent with the mass ratio of the tert-butyl ester group to the entire structure of the compound. Then continue to heat up until about 350 °C and weight loss begins again until the entire skeleton is completely decomposed at 500 °C. It can be seen from the DSC curve that the glass transition temperature of this material reaches 195 °C. The above results prove that the SBF-4N(Bu) we synthesized has good thermal stability (Td = 186 °C, Tg = 195 °C).

[0061] The above results prove that the SBF-4N(Bu) we synthesized has good thermal stability (Td = 186 °C).

[0062] (2) Fluorescence excitation spectrum and emission spectrum tests of the SBF-4N(Bu) compound prepared in Example 5. Test instrument and model: Cary 100 ultraviolet-visible spectrophotometer of Agilent Company in Malaysia. The specific test method is as follows. Dissolve the compound to be tested, SBF-4N(Bu), in dichloromethane to prepare a 1×10 -6 mol / L solution, and perform ultraviolet absorption spectrum test on it. When the absorbance of the solution of the compound to be tested is below 0.1, use the wavelength of its maximum absorption peak as the excitation wavelength to measure its fluorescence spectrum. The results are as Figure 3 shown. The excitation wavelength of this compound is 341 nm, and the emission wavelength is between 375 - 425 nm. The fluorescence quantum yield of the solution is 0.47.

[0063] (3) Figure 4 are pictures of the SBF-4N(Bu) compound prepared in Example 5 under natural light and ultraviolet light. It can be seen that it can emit blue fluorescence under ultraviolet light irradiation.

[0064] The above-described embodiments are the preferred embodiments of the present invention, rather than an exhaustive list of feasible embodiments of the present invention. For those skilled in the art, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and essence of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. Compounds of formula I: Among them, R is R a is or Each X is independently an alkyl group having 1 to 12 carbon atoms.

2. The compound according to claim 1, wherein R a For 3. The compound according to claim 2, wherein, R a For 4. The compound according to any one of claims 1 - 3, characterized in that, Each X is independently an alkyl group having 1 to 10 carbon atoms.

5. The compound according to any one of claims 1-3, characterized in that, Each X is independently an alkyl group having 1 to 5 carbon atoms.

6. The compound according to any one of claims 1-3, characterized in that, X is independently selected from methyl, ethyl, propyl, isopropyl, n-butyl.

7. The compound according to any one of claims 1-3, characterized in that, X is each independently methyl 8. The preparation method of the compound according to any one of claims 1-3, characterized in that, The reaction steps are as follows: 2,2',7,7'-Tetrabromo-9,9'-spirobifluorene and boronic acid pinacol ester derivatives are used to synthesize the compound through Suzuki coupling reaction; wherein, R a is defined in the same way as in claim 1.

9. An organic light-emitting material, characterized in that, The organic light-emitting material comprises one or several of the compounds described in any one of claims 1-3.

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