A blue fluorescent material based on fluoroboron diquinoline complex, and a preparation method and application thereof

Abstract

The application discloses a kind of blue fluorescent material based on fluoroboron diquinoline complex and its preparation method and application, the structure general formula of the material is as shown in chemical formula (I). The material of the application is by introducing big steric group, Dexter energy transfer between host / guest and dopant / dopant is conducive to limiting to occur, the occurrence of aggregation-induced quenching is inhibited, realizes high fluorescent quantum efficiency, high color purity and blue light, further expands its application in organic electroluminescent device.The material of the application can be used in organic light emitting diode, pH sensor, biological imaging and pressure sensor and multiple fields.

Description

Technical Field

[0001] This invention relates to a fluorescent material, its preparation method, and its application, specifically to a blue fluorescent material based on a fluoroboron diquinoline complex, its preparation method, and its application. Background Technology

[0002] Organic electroluminescence (OLED) refers to the phenomenon where organic materials emit light due to carrier injection and recombination driven by an electric field. The simplest OLED device structure consists of an anode, an organic light-emitting layer, and a cathode. As a dual-injection light-emitting device, OLEDs, driven by an external electric field, cause electrons and holes injected into the electrodes to recombine in the emitter layer, forming electron-hole pairs (called excitons). These excitons then emit photons through radiative transitions, producing visible light. With its irreplaceable advantages such as self-illumination, high contrast, energy efficiency, and ease of manufacturing, OLED has gradually gained a central position in the lighting and display market in recent years.

[0003] As one of the leading display technologies currently available, OLED displays face a major obstacle to future wide color gamut displays due to their wide emission range caused by strong electronic coupling between the ground and excited states. While color purity can be improved by commercially using color filters or optical microcavities that allow specific wavelengths to pass through, filtering the edge regions of the OLED's wide emission range, this results in light loss and a significant decrease in brightness compared to before the filter was introduced, leading to a substantial reduction in luminous efficiency.

[0004] Aza-boron-diquinomethene (aza-BODIQU) is a novel class of blue fluorescent narrow-bandgap materials, composed of a central boron-nitrogen six-membered heterocycle flanked by two quinolines. These derivatives are valued for their narrow emission peaks, nanosecond-level lifetimes, high thermal stability, high molar absorption coefficients, ease of synthesis, and high Φ. PL However, the rigid planar structure of large molecules leads to strong π-π interactions, which promotes intermolecular aggregation and causes aggregation-induced quenching (ACQ). Summary of the Invention

[0005] Objectives of the invention: This invention aims to provide a blue fluorescent material based on a fluoroboron diquinoline complex with excellent luminescence performance; another objective of this invention is to provide a method for preparing aza-BODIQU blue fluorescent material; yet another objective of this invention is to provide an application of aza-BODIQU blue fluorescent material in organic electroluminescent devices.

[0006] Technical Solution: This invention provides a series of aza-BODIQU materials with different steric hindrances. Theoretical calculations and spectroscopic measurements show that by directly introducing large-volume steric hindrance groups onto the aza-fluorinated boron diquinoline core, the tendency for intermolecular aggregation in aza-BODIQU materials is suppressed to a certain extent, achieving excellent luminescent properties. The blue fluorescent material based on the fluorinated boron diquinoline complex described in this invention has the general structural formula shown in formula (I):

[0007]

[0008] Where R1 is R2 is hydrogen or R3, R4, and R5 are selected from hydrogen, phenyl derivatives, or tert-butyl; R6 is selected from hydrogen, an alkyl chain with 1-12 carbon atoms, or tert-butyl. Preferably, R1 is selected from the following substituents:

[0009]

[0010]

[0011] Preferably, R3, R4, and R5 are selected from hydrogen or phenyl derivatives. Preferably, R6 is selected from alkyl chains with 1-5 carbon atoms or tert-butyl groups. R2 can be combined with R1 in any way.

[0012] Preferably, the blue fluorescent material has any one of the following structural formulas:

[0013]

[0014]

[0015] Fluoroborodiquinoline complexes with introduced sterically hindered groups exhibit excellent luminescent properties and are promising luminescent materials.

[0016] The blue fluorescent material of the fluoroboron diquinoline complex of the present invention is obtained by means including but not limited to: (i) modifying the 6-6' position of the fluoroboron diquinoline complex with a biphenyl derivative or a phenyl derivative, and modifying the 4-4' position with a phenyl derivative to obtain a fluoroboron diquinoline derivative. (ii) modifying the 6-6' position of the fluoroboron diquinoline complex with a biphenyl derivative to obtain a fluoroboron diquinoline derivative. Wherein R1 is selected from biphenyl, phenyl, or terphenylbenzene, and R2 is selected from hydrogen, phenyl, or tert-butylbenzene, wherein the fluoroboron diquinoline core structure is as shown in (II):

[0017]

[0018] The preparation method of the blue fluorescent material based on fluoroboron diquinoline complex of the present invention includes the following steps:

[0019] The preparation methods for fluoroboron diquinoline complexes are as follows (R2 is hydrogen) (Route 1 and Route 2 or Route 3):

[0020] (1) After dissolving 6-bromoquinoline in dichloromethane, m-chloroperoxybenzoic acid was slowly added to the mixed solution at room temperature, and then stirred for a period of time. After the reaction was complete, saturated sodium bicarbonate solution was slowly added until excess m-chloroperoxybenzoic acid was removed. Then the pH was adjusted with sodium hydroxide aqueous solution and extracted with dichloromethane. A white crude product solid was obtained. After drying, the white solid was dissolved in anhydrous dichloromethane, deionized water containing dissolved sodium hydroxide was added, and then benzoyl chloride was slowly added to the vigorously stirred mixture. The reaction was then carried out in an ice-water bath. After the reaction was complete, the precipitate was filtered and washed with water and dichloromethane respectively, and then dried in air to obtain a white solid product. The white solid product and phosphorus tribromooxy were dissolved in anhydrous toluene under nitrogen atmosphere and heated to reflux. After the reaction was complete, saturated sodium bicarbonate solution was slowly added until excess phosphorus tribromooxy was removed. The obtained organic compound was purified to obtain one of the bromine-substituted raw materials. The white crude product solid obtained above was dissolved in trifluorotoluene and chloroform under nitrogen atmosphere. After the solid dissolved, the reaction mixture was cooled in an ice-water bath. Tert-butylamine was then added, followed by the removal of the ice-water bath and the addition of p-toluenesulfonic anhydride with stirring. After a period of time, the reaction was complete. Trifluoroacetic acid was added to the system and the mixture was heated to reflux. After the reaction was complete, the pH was adjusted with saturated sodium hydroxide solution, and the resulting organic compound was purified to obtain one of the ammonia-substituted raw materials.

[0021] (2) Under nitrogen atmosphere, bis(2-diphenylphosphono) ether, sodium tert-butoxide, and the ammonia-substituted and bromine-substituted raw materials obtained in step (1) were dissolved in anhydrous toluene and palladium acetate was added. The reaction was then heated under reflux overnight. After the reaction was completed, the mixture was cooled to room temperature, diluted with tetrahydrofuran and diethyl ether, filtered, concentrated, and purified to obtain a white solid. The obtained white solid was dissolved in anhydrous toluene under nitrogen atmosphere. N,N-diisopropylethylamine was slowly added to the reaction. After stirring for a period of time, boron trifluoride diethyl ether was added dropwise, and the reaction was then heated to reflux. After the reaction was completed, the system was cooled to room temperature, the pH was adjusted to 7 with saturated sodium bicarbonate, and the organic matter was purified to obtain the yellowish-brown product bis(6-bromoquinoline-2-yl)amine difluoroboron complex.

[0022] (3) Method 1: Under nitrogen atmosphere, bis(6-bromoquinoline-2-yl)amine difluoroboron complex, phenyl derivative boric acid, and potassium carbonate are dissolved in 1,4-dioxane and water, and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride is added. The reaction is then heated to reflux. After the reaction is complete, the mixture is cooled to room temperature and filtered. The purified organic matter yields a bright yellow solid product, namely the fluoroboron difluoroline complex blue fluorescent material.

[0023] Alternatively, in method two: Dissolve the bis(6-bromoquinoline-2-yl)amine difluoroboron complex, potassium acetate, and pinacol diboronate in 1,4-dioxane, and add [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride under nitrogen atmosphere. Then, heat the reaction mixture under reflux. After the reaction is complete, purify the organic compound to obtain a yellow solid, bis(6-bromoquinoline-2-yl)amine difluoroboronate. Dissolve the obtained solid in tetrahydrofuran, add a certain volume of deionized water, and add potassium carbonate, a bromophenyl derivative, and tetra(triphenylphosphine)palladium under nitrogen atmosphere. Then, heat the mixture under reflux. After the reaction is complete, purify the organic compound to obtain a bright yellow solid product, namely the fluoroboron diquinoline complex blue fluorescent material.

[0024] Preferably, the volume ratio of dichloromethane to deionized water added during the white solid reaction in step (1) is 1:1 to 3; the volume ratio of trifluorotoluene to chloroform added during the white crude product solid reaction is 1 to 3:1. The preparation method of the fluoroboron diquinoline complex is as follows (R2 is a phenyl derivative) (Route 4 and Route 5):

[0025] (1) The 2-amino-5-chlorobenzophenone derivative was dissolved in tetrahydrofuran and stirred. The resulting mixture was then added to bis(trimethylsilyl)aminolithium in an ice-water bath, and stirred for a period of time before adding ethyl acetate. The reaction mixture was stirred at room temperature for a period of time, then deionized water was added, and the mixture was stirred again for a period of time. After the reaction was complete, the mixture was poured into ice water to form an aqueous suspension. The suspension was filtered to obtain a white solid. The white solid and phosphorus tribromooxyphosphate were dissolved in anhydrous toluene under nitrogen and heated to reflux. After the reaction was complete, the system was cooled to room temperature. The resulting mixture was poured into ice water, and saturated sodium bicarbonate solution was slowly added until excess phosphorus tribromooxyphosphate was removed, purifying the organic compound to obtain the brominated raw material. The 2-amino-5-chlorobenzophenone derivative was dissolved in anhydrous acetonitrile and stirred, then potassium hydroxide was added and heated to reflux under nitrogen. After the reaction was complete, the organic compound was purified to obtain an ammonia-containing raw material.

[0026] (2) Dissolve and stir the bis(2-diphenylphosphono) ether, sodium tert-butoxide, and the brominated and ammonia-containing raw materials obtained in step (1) in anhydrous toluene, and add palladium acetate under nitrogen. Heat the mixture until reflux. After the reaction is complete, cool the mixture to room temperature, dilute it with tetrahydrofuran and diethyl ether, filter, concentrate, and purify to obtain the product amine intermediate. Dissolve the amine intermediate in anhydrous toluene under nitrogen and stir, then slowly add N,N-diisopropylethylamine to the mixed solution. After stirring for a period of time, add boron trifluoride diethyl ether dropwise to the reaction system, and then heat the reaction to reflux. After the reaction is complete, cool the system to room temperature, adjust the pH to 7 with saturated sodium bicarbonate, and purify the organic matter to obtain the chlorine-containing intermediate. Add the chlorine-containing intermediate, phenyl derivative boric acid, tricyclohexylphosphine, and potassium phosphate to 1,4-dioxane, and then add tris(dibenzylideneacetone)dipalladium. Heat the mixture to reflux under nitrogen. After the reaction was completed, the organic matter was purified to obtain a yellow solid, namely the fluoroboron diquinoline complex, a blue fluorescent material.

[0027] Preferably, in step (1), the reaction time of the white solid and phosphorus tribromooxy is 18 to 24 hours, and the potassium hydroxide is in powder form with a reaction time of 8 to 16 hours.

[0028] Route 1

[0029]

[0030] Route 2

[0031]

[0032] Route 3

[0033] Route 4

[0034] Route 5

[0035] Compared with the traditional synthetic routes of aza-BODIQU derivatives, this invention proposes a novel synthetic route for such compounds, which has the following advantages: inexpensive raw materials, simple synthetic route, low risk, strong modifiability, high yield and no pollution.

[0036] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: the blue fluorescent material exhibits high fluorescence quantum efficiency, narrow full width at half maximum (FWHM), and blue light emission. Typical compounds in this invention are: R1 is a terphenyl complex and R2 is a hydrogen-substituted fluoroborondiquinoline complex; R1 is a 1,3,5-triphenylbenzene complex and R2 is a hydrogen-substituted fluoroborondiquinoline complex; and R2 is a phenyl complex and R1 is a phenyl-substituted fluoroborondiquinoline complex and R2 is a phenyl-substituted terphenyl complex. The yield is between 40-70%, and it exhibits a sharp and strong 1π-π* absorption band in the 350-460 nm range in toluene solution at room temperature, and strong blue-green emission light with a fine structure in the 440-470 nm range. Compared to the previously proposed aza-BODIQUs, the introduction of this sterically hindered group not only does not affect the luminescence performance of the core itself, but also helps to limit the Dexter energy transfer between the host / guest and dopants / dopants, suppressing intermolecular interactions. The resulting doped devices can achieve excellent blue light emission performance. Attached Figure Description

[0037] Figure 1 The normalized UV-Vis absorption (UV) and fluorescence emission (PL) spectra of C1 in toluene solution are shown.

[0038] Figure 2 The normalized UV-Vis absorption (UV) and fluorescence emission (PL) spectra of C2 in toluene solution are shown.

[0039] Figure 3 The normalized UV-Vis absorption (UV) and fluorescence emission (PL) spectra of D1 in toluene solution are shown.

[0040] Figure 4 The normalized UV-Vis absorption (UV) and fluorescence emission (PL) spectra of D2 in toluene solution are shown.

[0041] Figure 5 This is a schematic diagram of the structure of the doped device involved in this invention. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Example 1

[0044] The molecular structures of compounds C1 and C2 are shown below:

[0045]

[0046] The preparation methods for compounds C1 and C2 are as follows:

[0047] Step (1): Add 6-bromoquinoline (6.00 g, 26.7 mmol) and dichloromethane to a round-bottom flask. Add m-chloroperoxybenzoic acid (m-CPBA) (5.07 g, 29.4 mmol) slowly to the mixture at room temperature, and stir overnight. After the reaction is complete, slowly add saturated NaHCO3 solution until no CO2 gas is produced. Then treat with 3N NaOH aqueous solution until pH = 10, and extract with dichloromethane. Remove the solvent under reduced pressure to obtain a white crude product solid. Add anhydrous dichloromethane containing the above product and deionized water containing sodium hydroxide (1.38 g, 34.6 mmol) to a round-bottom flask (dichloromethane / deionized water = 1:2), then slowly add benzoyl chloride (25.5 mmol, 3.0 mL) to the vigorously stirred mixture. Then cool the round-bottom flask to 5°C in an ice-water bath. After stirring for 2 hours, the precipitate was filtered and washed with water and dichloromethane, respectively, and then dried in air to give a white solid product. The product and POBr3 (6.6 g, 23.1 mmol) were added to a flask, and the mixture was heated under reflux overnight in N2 atmosphere using anhydrous toluene as solvent. After the reaction was complete, the system was cooled to room temperature, and the mixture was slowly washed with saturated NaHCO3 solution until no CO2 gas was produced, followed by extraction with dichloromethane. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography to give 2,6-dibromoquinoline. The white crude product solid was dissolved in trifluorotoluene and chloroform (trifluorotoluene / chloroform = 2:1) under N2 conditions, and the system was cooled in an ice-water bath. Tert-butylamine (5.3 mL, 50.0 mmol) was then added, followed by the removal of the ice-water bath and the addition of Ts2O (6.50 g, 20.0 mmol) at 5–12 °C with stirring until the reaction was complete. The system was transferred from an ice-water bath to a sand bath, and 25 mL of trifluoroacetic acid was added. The reaction was carried out overnight at 70 °C. After the reaction was complete, most of the solvent was removed under reduced pressure. The remaining oily substance was diluted with dichloromethane and the pH was adjusted to 9-10 with saturated NaOH solution. The aqueous layer was extracted with dichloromethane. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography (2% methanol / dichloromethane) to obtain the desired gray solid 6-bromoquinoline-2-amine (1.39 g, 62.3% yield).

[0048] Step (2): Under N2 conditions, bis(2-diphenylphosphono) ether (0.3016 g, 0.560 mmol), 6-bromoquinoline-2-amine (3.28 g, 14.7 mmol), 2,6-dibromoquinoline (4.00 g, 14.0 mmol), t-BuONa (1.88 g, 19.6 mmol), and 120 mL of anhydrous toluene were added to a round-bottom flask. Palladium acetate (0.1258 g, 0.560 mmol) was then added, and the reaction was refluxed overnight at 110 °C. After the reaction was complete, the mixture was cooled to room temperature, diluted with tetrahydrofuran and diethyl ether, filtered, concentrated, and purified by silica gel column chromatography (2% methanol / dichloromethane) to give a white solid (3.52 g, yield 58.5%). Bis(6-bromoquinoline-2-yl)amine (1.40 g, 3.3 mmol) and dried toluene were added to a three-necked round-bottom flask under N2 conditions. N,N-diisopropylethylamine (1.6 mL, 9.9 mmol) was slowly injected into the system. After stirring for 10 minutes, boron trifluoride diethyl ether (3.5 mL, 13.2 mmol) was added dropwise to the three-necked round-bottom flask, and the reaction was refluxed overnight. After the reaction was complete, the system was cooled to room temperature, the pH was adjusted to 7 with saturated NaHCO3, and the mixture was extracted with dichloromethane. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography (dichloromethane) to give a yellowish-brown product. Under N2 conditions, bis(6-bromoquinoline-2-yl)amine difluoroboron complex (1.10 g, 2.3 mmol), (3,5-diphenylphenyl)boronic acid (1.92 g, 7.0 mmol), K2CO3 (0.63 g, 4.6 mmol), and 1,4-dioxane / water (3:1 v / v) were added to a round-bottom flask, followed by the addition of [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (0.0673 g, 0.0920 mmol, 0.4% mol). The reaction mixture was then heated under reflux at 100 °C overnight in an oil bath. After the reaction was complete, the mixture was cooled to room temperature and filtered. The aqueous layer was diluted with dichloromethane and extracted, and the combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure. Purification by silica gel column chromatography (2% methanol / dichloromethane) gave a bright yellow solid, product C1 (0.6 g, 59.8% yield).

[0049] Step (3): Bis(6-bromoquinoline-2-yl)amine difluoroboron complex (1.00 g, 2.1 mmol), KOAc (0.36 g, 3.6 mmol), pinacol diborate (0.91 g, 3.6 mmol), and 1,4-dioxane were added to a round-bottom flask. Finally, [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (0.0614 g, 0.0840 mmol, 0.4% mol) was added under N2 conditions, and the reaction was heated under reflux overnight. After the reaction was complete, the mixture was cooled to room temperature and dried by filtration with MgSO4. The solvent was removed under reduced pressure, and the desired yellow solid intermediate was obtained by silica gel column chromatography (2% methanol / dichloromethane). The resulting solid was dissolved in tetrahydrofuran and a certain volume of deionized water was added (tetrahydrofuran / water = 3:1). K₂CO₃ (0.53 g, 3.9 mmol), 2,4,6-triphenylbromobenzene (1.50 g, 3.9 mmol), and tetra(triphenylphosphine)palladium (0.0601 g, 0.0520 mmol, 0.4% mol) were added under N₂ conditions, and the mixture was refluxed overnight. After the reaction was complete, the mixture was cooled to room temperature, diluted with dichloromethane, and filtered. The aqueous layer was extracted with dichloromethane, and the combined organic layers were dried over MgSO₄. The solvent was removed under reduced pressure. Purification by silica gel column chromatography (dichloromethane) yielded a bright yellow solid product C₂ (1.1 g, 42.3%).

[0050] C1 mass spectrometry: 775.3526. C2 mass spectrometry: 927.4378.

[0051] C1 elemental analysis results: C, 83.25; H, 4.75; N, 5.62. C2 elemental analysis results: C, 85.19; H, 4.85; N, 4.67.

[0052] The specific synthesis route is shown below:

[0053]

[0054] The UV absorption and fluorescence spectra of the synthesized C1 are as follows: Figure 1 As shown. The main absorption peak of C1 in toluene is 456 nm, the emission peak is 464 nm, the full width at half maximum (FWHM) is 12 nm, and the Stokes shift is 8 nm; the UV absorption and fluorescence spectra of the synthesized C2 are shown below. Figure 2As shown, C2 in toluene has a main absorption peak at 455 nm, an emission peak at 461 nm, a full width at half maximum (FWHM) of 12 nm, and a Stokes shift of 7 nm. The fabricated related doped device structure is ITO / PEDOT:PSS (45 nm) / Cx:Xwt%PhCz-3CzBN (100 nm) / TPBi (40 nm) / Cs2CO3 (2 nm) / Al (100 nm). The emissive layer (EML) consists of 2wt% doped C1 and C2, achieving EQEmax of 0.40% and 1.20%, respectively.

[0055] Example 2

[0056] The molecular structures of compounds D1 and D2 are shown below:

[0057]

[0058] The preparation methods for compounds D1 and D2 are as follows:

[0059] Step (1): Add 2-amino-5-chlorobenzophenone (231 mg, 1 mmol) and tetrahydrofuran (5 mL) to a three-necked round-bottom flask and stir. Cool the resulting mixture to 0 °C in an ice-water bath and add 6 mL of LiHMDS (1 MTF) over 5 minutes. Keep the internal temperature below 5 °C for 10 minutes, then add ethyl acetate (144 mg, 2 mmol) over 1 minute. Heat the reaction solution to room temperature and stir at room temperature for 2 hours, then add water (5 mL) and stir the reaction mixture again at room temperature for 24 hours. Finally, pour the reaction mixture into ice water to form an aqueous suspension, and filter the suspension to obtain a white solid Cl-1. Add the above white solid, POBr3 (485 mg, 1.7 mmol), and dry toluene to a round-bottom flask under N2 conditions and heat under reflux overnight. After the reaction is complete, cool the system to room temperature. The resulting mixture was poured into ice water, and saturated NaHCO3 solution was slowly added for washing until no CO2 gas was produced. The aqueous layer was extracted several times with dichloromethane. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography to give 2-bromo-6-chloro-4-phenylquinoline. 2-Amino-5-chlorobenzophenone (231 mg, 1 mmol) was dissolved in a round-bottom flask containing anhydrous acetonitrile and stirred until completely dissolved. KOH powder (168 mg, 3 mmol) was then added and refluxed overnight under N2 conditions. After the reaction was complete, the mixture was cooled to room temperature. The mixture was extracted with ethyl acetate. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography (dichloromethane) to give 6-chloro-4-phenylquinoline-2-amine (0.20 g, 76.9%).

[0060] Step (2): Bis(2-diphenylphosphono) ether (0.3016 g, 0.560 mmol, 4% mmol), 2-bromo-6-chloro-4-phenylquinoline (4.46 g, 14.0 mmol), 6-chloro-4-phenylquinoline-2-amine (3.74 g, 14.7 mmol), t-BuONa (1.88 g, 19.6 mmol), and anhydrous toluene were added to a round-bottom flask, and finally palladium acetate (0.1258 g, 0.560 mmol, 4% mmol) was added. The reaction was heated under N2 and refluxed overnight. After the reaction was complete, the mixture was cooled to room temperature, diluted with tetrahydrofuran and diethyl ether, filtered, concentrated, and purified by silica gel column chromatography (2% methanol / dichloromethane) to obtain bis(6-chloro-4-phenylquinoline-2-yl)amine. Under N2 conditions, bis(6-chloro-4-phenylquinoline-2-yl)amine (1.62 g, 3.3 mmol) and anhydrous toluene were added to a three-necked round-bottom flask and stirred. Then, N,N-diisopropylethylamine (1.6 mL, 9.9 mmol) was slowly added to the mixture. After stirring for 10 minutes, boron trifluoride diethyl ether (3.5 mL, 13.2 mmol) was added dropwise to the three-necked round-bottom flask, and the reaction was refluxed overnight. After the reaction was complete, the system was cooled to room temperature, the pH was adjusted to 7 with saturated NaHCO3, and the mixture was extracted with dichloromethane. The combined organic layers were dried over MgSO4. The solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography (dichloromethane) to give product Cl-5. To a round-bottom flask, add Cl-5 (0.27 g, 0.5 mmol), phenylboronic acid (0.27 g, 2.2 mmol), tris(dibenzylacetone)palladium (0.045 g, 0.05 mmol), PCy3 (0.014 g, 0.05 mmol), and K3PO4 (0.47 g, 2.2 mmol), using 1,4-dioxane as the solvent. Heat the mixture under reflux for 48 hours in N2. After the reaction is complete, extract the reaction mixture with dichloromethane and saturated brine. Dry the organic layer with MgSO4 and filter. Remove the solvent under reduced pressure and purify the product by silica gel column chromatography (dichloromethane) to give a yellow solid D1 (0.26 g, 80.6%). The reaction starting materials were Cl-5 (0.27 g, 0.5 mmol) and (3,5-diphenylbenzene)boronic acid (0.60 g, 2.2 mmol). Other reaction conditions and post-treatment were similar to those of D1. The product was purified by silica gel column chromatography (dichloromethane) to give yellow solid D2 (0.24 g, 73.5%).

[0061] D1 mass spectrometry: 623.03. D2 mass spectrometry: 927.65.

[0062] Elemental analysis results for D1: C, 80.56; H, 4.67; N, 6.81. Elemental analysis results for D2: C, 85.12; H, 4.81; N, 4.59.

[0063] The specific synthesis route is shown below:

[0064]

[0065]

[0066] The UV absorption and fluorescence spectra of the synthesized D1 are as follows: Figure 3 As shown. The main absorption peak of D1 in toluene is 456 nm, the emission peak is 474 nm, the full width at half maximum (FWHM) is 17 nm, and the Stokes shift is 12 nm; the UV absorption and fluorescence spectra of the synthesized D2 are shown below. Figure 3 As shown. The main absorption peak of D2 in toluene is 462 nm, the emission peak is 476 nm, the full width at half maximum (FWHM) is 18 nm, and the Stokes shift is 14 nm. The structure of the fabricated correlated doped device is ITO / PEDOT:PSS (45 nm) / Dx:X wt% PhCz-3CzBN (100 nm) / TPBi (40 nm) / Cs2CO3 (2 nm) / Al (100 nm), as shown in the figure. Figure 5 As shown in the figure. The light-emitting layers (EML) are D1 and D2 with a doping concentration of 2wt%, achieving EQEmax of 0.32% and 0.67%, respectively.

Claims

1. A blue fluorescent material based on a fluoroborate dipyridyl complex, characterized in that, The blue fluorescent material is: 。 2. A method for preparing a blue fluorescent material based on a fluoroboron diquinoline complex as described in claim 1, characterized in that, The reaction route for synthesizing this material is as follows: The aforementioned Specifically: ； Alternatively, the reaction route for synthesizing this material is as follows: The aforementioned Specifically: 。 3. The method for preparing blue fluorescent materials based on fluoroboron diquinoline complexes according to claim 2, characterized in that, The preparation process includes the following steps: (1) After dissolving 6-bromoquinoline, add m-chloroperoxybenzoic acid and stir. After the reaction is complete, add saturated sodium bicarbonate solution until the excess m-chloroperoxybenzoic acid is removed. Then adjust the pH and extract to obtain a white crude product solid. Dissolve the white solid in a solvent, add deionized water containing sodium hydroxide, and then add benzoyl chloride to the vigorously stirred mixture. React under an ice-water bath. After the reaction is complete, filter the precipitate and wash and dry to obtain a white solid product. Dissolve the white solid product and phosphorus tribromooxy in a solvent under nitrogen atmosphere, heat to reflux, and after the reaction is complete, add saturated sodium bicarbonate solution until the excess phosphorus tribromooxy is removed. Purify the obtained organic matter to obtain one of the bromine-substituted raw materials. Dissolve the white crude product solid obtained above in a solvent under nitrogen atmosphere, cool the reaction in an ice-water bath, then add tert-butylamine, then remove the ice-water bath and add p-toluenesulfonic anhydride and stir. After the reaction is complete, add trifluoroacetic acid to the system and heat to reflux. Adjust the pH and purify the obtained organic matter to obtain one of the ammonia-substituted raw materials. (2) Under nitrogen conditions, bis(2-diphenylphosphono) ether, sodium tert-butoxide, and the above-obtained ammonia-substituted and bromine-substituted raw materials were dissolved in a solvent and palladium acetate was added. The mixture was heated under reflux overnight. After the reaction was completed, the mixture was diluted with a solvent, filtered, concentrated, and the organic matter was purified to obtain a white solid. The white solid was dissolved, N,N-diisopropylethylamine was added, and after stirring, boron trifluoride ether was added dropwise. The mixture was heated under reflux. After the reaction was completed, the pH of the reaction solution was adjusted, and the organic matter was purified to obtain the yellowish-brown product bis(6-bromoquinoline-2-yl)amine difluoroboron complex. (3) Method 1: Under nitrogen conditions, bis(6-bromoquinoline-2-yl)amine difluoroboron complex, phenyl derivative boric acid, and potassium carbonate are dissolved in solvent and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride is added. The reaction is then heated to reflux. After the reaction is completed, the mixture is cooled to room temperature and filtered to purify the organic matter and obtain the final product, namely the fluoroboron diquinoline complex blue fluorescent material. Alternatively, in method two: bis(6-bromoquinoline-2-yl)amine difluoroboron complex, potassium acetate, and pinacol diboronate are dissolved in 1,4-dioxane, and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride is added under nitrogen. The reaction is then heated to reflux. After the reaction is complete, the organic matter is purified to obtain bis(6-bromoquinoline-2-yl)amine difluoroboronate. The obtained solid is dissolved and deionized water is added. Under nitrogen, potassium carbonate, bromophenyl derivative, and tetra(triphenylphosphine)palladium are added, and the mixture is heated to reflux again. After the reaction is complete, the mixture is cooled to room temperature and filtered. The organic matter is purified to obtain the final product, the fluoroboron diquinoline complex blue fluorescent material.

4. The method for preparing blue fluorescent materials based on fluoroboron diquinoline complexes according to claim 2, characterized in that, The preparation process includes the following steps: (1) Dissolve and stir the 2-amino-5-chlorobenzophenone derivative, add bis(trimethylsilyl)aminolithium in an ice-water bath, stir, add ethyl acetate, then add deionized water and continue stirring. After the reaction is complete, pour the mixed solution into ice water and filter the suspension to obtain a white solid. Dissolve the white solid and phosphorus tribromooxy under nitrogen and heat under reflux. After the reaction is complete, pour the resulting mixed solution into ice water and add saturated sodium bicarbonate solution until the excess phosphorus tribromooxy is removed. Purify the organic matter to obtain the brominated raw material. Dissolve and stir the 2-amino-5-chlorobenzophenone derivative, add potassium hydroxide and heat under nitrogen under reflux. After the reaction is complete, purify the organic matter to obtain the ammonia-containing raw material. (2) Dissolve and stir bis(2-diphenylphosphono) ether, sodium tert-butoxide, the above-mentioned brominated raw materials and ammonia-containing raw materials, add palladium acetate under nitrogen, heat the reaction until reflux, and after the reaction is completed, purify to obtain the product amine intermediate; dissolve and stir the amine intermediate under nitrogen, add N,N-diisopropylethylamine, then add boron trifluoride ethyl ether dropwise, then heat the reaction to reflux, adjust the pH of the reaction solution after the reaction is completed, and purify the organic matter to obtain the chlorine-containing intermediate; add the chlorine-containing intermediate, phenyl derivative boric acid, tricyclohexylphosphine and potassium phosphate to 1,4-dioxane, then add tris(dibenzylideneacetone)dipalladium, heat the reaction under nitrogen and reflux, and after the reaction is completed, purify the organic matter to obtain the final product, namely the fluoroboron diquinoline complex blue fluorescent material.

5. The method for preparing blue fluorescent material based on fluoroboron diquinoline complex according to claim 4, characterized in that, In step (1), the reaction time of adding potassium hydroxide and heating under nitrogen reflux is 8 to 16 hours.

6. The application of the blue fluorescent material based on fluoroboron diquinoline complex as described in claim 1 in organic electroluminescent devices.

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