Synthesis method of blue light hole blocking material based on dibenzofuran group

Abstract

The invention relates to the field of electroluminescent materials, in particular to a synthesis method of a blue light hole blocking material based on a dibenzofuran group. The synthesis raw materials of the blue light hole blocking material comprise dibenzofuran and phenyl-containing phosphonate. The blue light hole blocking material has hole transmission and exciton blocking performance, is suitable for various organic light-emitting devices, enables the organic light-emitting devices to show high thermal stability, and further has good light-emitting life and light-emitting efficiency. And the material has the advantages of mild preparation conditions, high product yield, high purity and environment-friendly synthesis process, and can be popularized in industrial production.

Description

Technical Field

[0001] The invention relates to the field of electroluminescent materials, and in particular to a method for synthesizing a blue light hole blocking material based on a dibenzofuran group. Background Art

[0002] According to the principle of luminescence, voltage is applied to the organic electroluminescent element, and holes from the anode and electrons from the cathode are injected. In order to make the electrons and holes reach the light-emitting layer at the same time and avoid possible electrons or possible excitons from entering the hole transport layer to deteriorate the light-emitting device, it is often necessary to use a layer of material that has both hole transport function and the ability to block electrons and excitons between the light-emitting layer and the hole transport layer. Blue light materials often face problems such as low luminescence efficiency and concentration quenching due to their wide band gap, and the poor matching between blue light hole blocking materials and hole injection layer materials, resulting in poor luminescence efficiency and stability. Therefore, it is necessary to develop a method for synthesizing blue light hole blocking materials that has both hole transport and exciton blocking properties based on the characteristics of blue light hole blocking materials, suitable for OLED organic light-emitting devices, and exhibit good luminescence efficiency, good operating life and high thermal stability. It is quite challenging to develop a greener, cleaner and more efficient method for synthesizing blue light hole blocking materials. Summary of the invention

[0003] In order to effectively improve the above problems, the present application provides a method for synthesizing a blue light hole blocking material based on a dibenzofuran group, which is a greener, cleaner and more efficient synthetic blue light blocking compound, so that it has both hole transport and exciton blocking properties, is suitable for various types of organic light-emitting devices, exhibits high thermal stability, and thus has good operating life and luminous efficiency.

[0004] The present application provides a method for synthesizing a blue light hole blocking material based on a dibenzofuran group, using the following technical solution: The synthesis method of a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) adding dibenzofuran to tetrahydrofuran and stirring, and under nitrogen protection, the temperature is reduced to -70 to -50°C, and under an alkaline catalytic environment, the temperature is controlled at -50 to -40°C by stirring. After the addition is completed, the reaction is kept warm for 2-3 hours, and then the temperature is raised to room temperature for 12-18 hours to obtain a mixture A; (2) At -75 to -60°C, add tetrahydrofuran to a phenyl-containing phosphonate and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature, react for 2 to 3 hours, then raise the temperature to room temperature and continue the reaction for 4 to 6 hours; (3) The mixture after the reaction in step (2) was cooled to 0-5°C, diluted hydrochloric acid was added dropwise to quench the reaction, stirred for 3-5 minutes, and allowed to stand for stratification; the aqueous phase was extracted again, the organic phases were combined, washed, and dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oily product, which was purified by silica gel column to obtain the target compound; The phenyl-containing phosphonate includes at least one of ethyl phenylphosphonate, ethyl diphenylphosphonate, ethyl 2,4,6-trimethylbenzoylphenylphosphonate and ethyl 3-carbonyl-4-(triphenylphosphine)butyrate.

[0005] Preferably, the phenyl-containing phosphonate includes ethyl phenylphosphonate; preferably, the phenyl-containing phosphonate also includes ethyl 3-carbonyl-4-(triphenylphosphine)butyrate, and the molar mass ratio of ethyl phenylphosphonate to ethyl 3-carbonyl-4-(triphenylphosphine)butyrate is 1:(0.5-1).

[0006] By adopting the above technical scheme, the applicant discovered that the asymmetric double-barreled dibenzofuran has a large spatial volume and is used as a blue light hole blocking material donor, which can extend the molecular skeleton of the macromolecular non-conjugated fragment, thereby increasing the distance between adjacent luminophore molecules, weakening the interaction between molecules, and effectively reducing aggregation quenching; by further modifying the dibenzofuran structural unit by introducing phenylphosphonic acid groups, the phenylphosphonic acid groups connect different aromatic group-containing structures through CP saturated bonds, which can not only further effectively block the conjugation effect, so that the blue light blocking material maintains a higher triplet energy level, inhibiting non-radiative transitions and excited state quenching caused by intermolecular interactions, but also the high triplet energy level can inhibit the photo-oxidation aging and electro-oxidation aging processes of the device, enhance the stability of the material and extend the fluorescence lifetime, and can achieve ultra-low voltage driving, so that the current efficiency of the device is increased. Therefore, the compounds synthesized with dibenzofuran and phenyl-containing phosphonates as raw materials, on the one hand, have a higher triplet energy level and are suitable as blue light blocking materials with hole transport and exciton blocking properties; on the other hand, they avoid the problems of complex reaction systems, many by-products, low yields, and difficult separation caused by the reaction of heterocyclic donors with aromatic amides and aromatic hydrazides.

[0007] The method adopts relatively cheap and readily available dibenzofuran and phenyl-containing phosphonate as reaction raw materials. Phosphate in the phenyl-containing phosphonate as the reaction raw material is an important building block for synthesis. Due to the strong inductive effect of different phenyl-containing phosphates, it can be directly substituted with dibenzofuran under relatively mild conditions. By adding a compound catalyzed in an appropriate proportion, the dibenzofuran group is promoted to be deprotonated, and the heteroatom anion or the formed carbon anion can be stabilized by the ion of the conjugated effect. Therefore, the substrate of the dibenzofuran compound can be easily catalyzed to form a highly active intermediate, thereby reducing the reaction energy barrier, increasing the reaction rate, and causing the substitution reaction to occur more efficiently and selectively. After extraction, concentration and other processes, the reaction is promoted to move in the direction of the product, the generation of by-products is inhibited, the purity and yield of the product are further improved, and the energy consumption is greatly reduced. Unlike using dibenzofuranyl carboxylic acid and phenylphosphine oxide as reaction raw materials, a cross-coupling reaction occurs by adding a noble metal catalyst. The reaction has a narrow range of applicable substrates, and it is more difficult to modify dibenzofuran with more complex phenylphosphonate-containing reactants. The molecular design is very limited, the reaction system is complex, and high temperature and oxidants are required. Most of them require multi-step reactions. High temperature produces more toxic organic and inorganic by-products, which can easily cause environmental pollution and waste of resources. In addition, the raw materials are expensive, the operation is complicated, and the reaction conditions are harsh and need to be completed in a glove box. Not only are there many reaction steps, but the reaction time is long and the yield is lower, which is not suitable for promotion and use as a blue light blocking material. Therefore, the present application adopts a more green, clean, and efficient synthetic blue light blocking compound with fewer reaction by-products and high separation efficiency.

[0008] Through the molecular design of the synthesis of blue light hole blocking compounds based on dibenzofuran groups, by reacting specifically selected phenyl-containing phosphonates with dibenzofuran, the phosphonate group in the phenyl-containing phosphonate has strong coordination ability and the electron-withdrawing effect of the phenyl group, making it easier to react with dibenzofuran, thereby improving the efficiency of the substitution reaction and the chemical stability of the blue light hole blocking compound. Taking into account the effects of compound synthesis conditions, steric hindrance, etc. on the yield and stability of aromatic phosphorus oxide compounds, phenyl-containing phosphonates can reduce conjugation to ensure a higher triplet energy level, thereby ensuring a reaction raw material with good blue light blocking efficiency and a higher synthesis yield.

[0009] The steric hindrance effect is further enhanced by the addition of ethyl 3-carbonyl-4-(triphenylphosphine)butyrate. The main functional group of ethyl 3-carbonyl-4-(triphenylphosphine)butyrate has a large planar structure and strong electron-withdrawing ability, which further interrupts the conjugation and ensures a higher triplet energy level. The steric hindrance effect of the main ethyl 3-carbonyl-4-(triphenylphosphine)butyrate can improve the rigidity of the molecular structure, have higher thermodynamic stability, inhibit non-radiative transitions caused by intermolecular interactions, and improve the fluorescence quantum yield of the material, thereby improving the luminescence efficiency of the material. The unsaturated group of P has the effects of electron induction and polarization of molecules, which can improve the electron injection and transmission ability of the molecule. The carrier transmission ability of the entire molecule is regulated by adjusting the number and modification position of the modification group, so that the triplet excited state energy level is higher and has good carrier injection and transmission ability.

[0010] In a specific embodiment, the molar ratio of dibenzofuran to phenylphosphonate is 1:(0.9-1.2).

[0011] By adopting the above technical scheme, the molar ratio of the reaction raw materials is optimized, and the 2nd, 4th and 6th positions of dibenzofuran can be selectively substituted, reducing the generation of by-products and improving the selectivity of aromatic phosphorus oxide compounds with specific molecular structures in organic reactions. The purity and yield of aromatic phosphorus oxide compound products are further improved, and the crystalline form of aromatic phosphorus oxide compounds is made more complete, preventing an excessive amount of one reactant from generating impurities from other reactions, making separation difficult and affecting the yield, especially when the content of phenyl-containing phosphonates is too high, when the 2nd, 4th and 6th positions of dibenzofuran are all highly active, it is necessary to consider molecular selection and steric hindrance effects, molecular design is difficult, there are many by-products, and the yield is reduced.

[0012] In a specific embodiment, the catalytic environment in step (1) is to add n-butyl lithium or a mixture of n-butyl lithium and 1,4-diazabicyclo[2.2.2]octane into the system.

[0013] Preferably, the mass ratio of n-butyl lithium to 1,4-diazabicyclo[2.2.2]octane is 1:(0.5-0.8).

[0014] By adopting the above technical solution, in the catalytic environment, n-butyl lithium is selected as a catalytic reagent, and then the electron-deficient n-butyl lithium is reacted through the electron-donating group of 1,4-diazabicyclo[2.2.2]octane. Therefore, 1,4-diazabicyclo[2.2.2]octane is used as an active ligand to promote the aggregation of low-order organic lithium, making it easier to react with dibenzofuran, greatly reducing the energy barrier of subsequent substitution reactions. If the content of the active ligand of 1,4-diazabicyclo[2.2.2]octane is too high, there may be too many impurities in the reaction product, making it difficult to separate.

[0015] In a specific embodiment, the temperature adjusted in step (2) is -55 to 45°C.

[0016] The temperature during the substitution reaction is adjusted so that the alkaline reagent and tetrahydrofuran are dissolved to form a stable solvent system, so that the reactants are fully contacted, and adverse reactions are avoided to reduce the yield. The effect of the reaction temperature on the synthetic product of the substitution reaction is further optimized. Too high a temperature is likely to produce unnecessary by-products, which affects the yield of the compound, increases the difficulty of the separation operation, increases energy consumption and cost, and is not conducive to industrial production.

[0017] In a specific implementation manner, the specific extraction operation in step (3) is: adding ethyl acetate, stirring, standing, and collecting the organic phase.

[0018] By adopting the above technical solution, ethyl acetate is used as an extractant to extract the residual product in the aqueous phase, and ethyl acetate is used as an extractant to increase the contact area between the product system and the unreacted raw materials, thereby improving the extraction efficiency and speed and facilitating collection, separation and treatment.

[0019] In summary, the present application includes at least one of the following beneficial technical effects: 1. Asymmetric bifunctionalized dibenzofuran has a large spatial volume and is used as a donor for blue light hole blocking materials. It can extend the molecular skeleton of the macromolecular non-conjugated fragment and weaken the interaction between molecules, thereby effectively reducing aggregation quenching. By further modifying the dibenzofuran structural unit by introducing phenylphosphonic acid groups, the phenylphosphonic acid groups connect different structures containing aromatic groups through CP saturated bonds, which can further effectively block the conjugation effect, inhibit excited state quenching and the photo-oxidative aging and electro-oxidative aging processes of the device, enhance the stability of the material and thus extend the life of the device. Therefore, the compounds synthesized using dibenzofuran and phenyl-containing phosphonates as raw materials have, on the one hand, a higher triplet energy level and high cleavage stability, and are suitable as blue light blocking materials with hole transport and exciton blocking properties. On the other hand, they avoid the reaction of heterocyclic donors with aromatic amides and aromatic hydrazides, etc., resulting in a complex reaction system, many by-products, low yield, and difficult separation.

[0020] 2. By optimizing the molar ratio of the reaction raw materials, the 2nd, 4th and 6th positions of dibenzofuran can be selectively substituted to reduce the generation of by-products and the probability of by-product generation, thereby further improving the purity and yield of the aromatic phosphorus oxide compound product, and making the aromatic phosphorus oxide compound crystal form more complete, thereby preventing an excess of one reactant from generating impurities through other reactions, making separation difficult and affecting the yield.

[0021] 3. Select n-butyl lithium as the catalytic reagent, and then react with the nucleophilic reagent n-butyl lithium through the electron-donating group of 1,4-diazabicyclo[2.2.2]octane. 1,4-diazabicyclo[2.2.2]octane can act as an active ligand to promote the aggregation of low-order organic lithium, making it easier to react with dibenzofuran, greatly reducing the energy barrier of the subsequent substitution reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a PNMR graph of the blue light hole blocking material compound prepared in Example 1 of the present application.

[0023] Figure 2 This is the HNMR graph of the blue light hole blocking material compound prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0024] 37% concentrated hydrochloric acid: analytical grade, purchased from Yangzhou Huafu Chemical Co., Ltd. The dilute hydrochloric acid in this application refers to 15% hydrochloric acid by mass and 1% dilute hydrochloric acid by mass, both of which are obtained by diluting concentrated hydrochloric acid with deionized water; 3-carbonyl-4-(triphenylphosphine)butyric acid ethyl ester was purchased from Aladdin; other raw materials can be obtained commercially. Example 1

[0025] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group, the synthesis route is shown below:

[0026] The specific steps include: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, 375 mL of n-butyl lithium was added, and the temperature was controlled at -40 °C with stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 12 h to obtain a mixture A; (2) At -75°C, add 167.1 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 4 h; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for stratification. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After stratification, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data (refer to Figure 1 and Figure 2): PNMR and HNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 98.2% and the yield was 77.6%. Example 2

[0027] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, and 375 mL of n-butyl lithium was added. The temperature was controlled at -50 °C by stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 18 h to obtain a mixture A. (2) At -75°C, add 167.1 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 6 h; (3) The mixture after the reaction in (2) was cooled to 5°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 3 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. Then, water with a volume of 1 times the volume of the filtrate was added, stirred, allowed to stand, and separated. The organic phase was collected, and the two organic phases were combined. Then, the organic phase was washed once with 2 L of 1% dilute hydrochloric acid by mass fraction. After separation, the organic phase was dried with anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product. The crude oil product was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 98.1% and the yield was 77.7%. Example 3

[0028] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, 375 mL of n-butyl lithium was added, and the temperature was controlled at -40 °C with stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 12 h to obtain a mixture A; (2) At -75°C, 473.8 g of a phenyl-containing phosphonate was added to 300 mL of tetrahydrofuran and stirred evenly, and then added dropwise to mixture A. After the addition was completed, the temperature was adjusted to -45°C, and the reaction was continued for 3 hours. The temperature was then raised to room temperature and the reaction was continued for 4 hours. The phenyl-containing phosphonate was a mixture of ethyl phenylphosphonate and ethyl 3-carbonyl-4-(triphenylphosphine)butyrate in a molar ratio of 1:0.8; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for stratification. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After stratification, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 97.2% and the yield was 77.1%. Example 4

[0029] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, 375 mL of n-butyl lithium was added, and the temperature was controlled at -40 °C with stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 12 h to obtain a mixture A; (2) At -75°C, add 383.3 g of ethyl 3-carbonyl-4-(triphenylphosphine)butyrate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 4 h; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After separation, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 95.4% and the yield was 76.7%. Example 5

[0030] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, 375 mL of n-butyl lithium was added, and the temperature was controlled at -40 °C with stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 12 h to obtain a mixture A; (2) At -75°C, add 187.1 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 hours, then raise the temperature to room temperature and continue the reaction for 4 hours; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After separation, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 97.8% and the yield was 77.5%. Example 6

[0031] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50 °C, 375 mL of n-butyl lithium was added, and the temperature was controlled at -40 °C with stirring. After the addition was completed, the reaction was kept warm for 2 h, and then the temperature was raised to room temperature for 12 h to obtain a mixture A; (2) At -75°C, add 101 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 4 h; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After separation, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 97.3% and the yield was 72.1%. Example 7

[0032] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50°C, and a catalyst was added. The catalyst was a mixed solution of n-butyl lithium and 1,4-diazabicyclo[2.2.2]octane in a mass ratio of 1:0.8, and the mass of the n-butyl lithium in Example 1 was replaced by the catalyst. The temperature was controlled at -40°C while stirring. After the addition was completed, the reaction was kept warm for 2 hours, and then the temperature was raised to room temperature for 12 hours to obtain a mixture A; (2) At -75°C, add 167.1 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 4 h; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After separation, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 98.8% and the yield was 78.5%. Example 8

[0033] A method for synthesizing a blue light hole blocking material based on a dibenzofuran group comprises the following steps: (1) 150 g of dibenzofuran was added to 750 mL of tetrahydrofuran and stirred. Under nitrogen protection, the temperature was lowered to -50°C, and a catalyst was added. The catalyst was a mixed solution of n-butyl lithium and 1,4-diazabicyclo[2.2.2]octane in a mass ratio of 1:1, and the n-butyl lithium in Example 1 was replaced by the same mass. The temperature was controlled at -40°C while stirring. After the addition was completed, the mixture was kept warm for 2 hours and then heated to room temperature for 12 hours to obtain a mixture A. (2) At -75°C, add 167.1 g of ethyl phenylphosphonate to 300 mL of tetrahydrofuran and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature to -45°C, react for 3 h, then raise the temperature to room temperature and continue the reaction for 4 h; (3) The mixture after the reaction in (2) was cooled to 0°C, 100 mL of 15% dilute hydrochloric acid was added to quench the reaction, stirred for 5 min, and allowed to stand for separation. After separation, 1 L of ethyl acetate was added to the aqueous phase, stirred, allowed to stand, and the organic phase was collected. The organic phases were combined twice and washed once with 2 L of 1% dilute hydrochloric acid. After separation, the organic phase was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oil product, which was purified by silica gel column (petroleum ether: ethyl acetate = 20:1 v / v) to obtain the target compound. Structural characterization data: HNMR and PNMR analysis determined the hydrogen environment and element content of the compound to determine the molecular structure and molecular formula; the content was 98.4% and the yield was 77.9%.

[0034] Comparative Example 1: Existing blue light hole blocking material: 4,4,4,-tri(carbazole-9-yl)triphenylamine.

[0035] The compounds prepared in Examples 1-8 and Comparative Example 1 were subjected to thermal decomposition tests using a DTG-60H TG / DTA thermogravimetric analyzer produced by Shimadzu Corporation of Japan. The tests were carried out in a nitrogen atmosphere, starting from room temperature at 15°C / min -1 The temperature was raised to 800°C at a heating rate to test the initial cracking temperature; the test results are shown in Table 1: Table 1 Performance test results

[0036] It can be seen from the experimental data that the blue light hole blocking material based on dibenzofuran group prepared in Examples 1-7 of the present application has greatly improved the cracking temperature compared with that of Comparative Example 1; in combination with Example 1 and Examples 5-6, it can be seen that the ratio of raw material content within the specified range can obtain products with better purity and yield; in combination with Example 1 and Examples 3-4, it can be seen that by using ethyl phenylphosphonate and ethyl 3-carbonyl-4-(triphenylphosphine)butyrate in combination and limiting the mass ratio of the two, the prepared blue light hole blocking layer material has a better cracking temperature and blue light blocking effect than using a phenyl-containing phosphonate alone; in combination with Example 1 and Examples 7-8, it can be seen that selecting a compounded catalyst and adjusting the ratio of the catalyst within a suitable ratio range can achieve more effective catalysis, thereby improving the purity and yield, and then obtaining a high-purity blue light hole blocking layer material, and its cracking temperature is significantly improved, thereby improving the application performance of the material.

[0037] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for synthesizing a blue light hole blocking material based on a dibenzofuran group, characterized in that: The following steps are included: (1) Add dibenzofuran to tetrahydrofuran and stir. Under nitrogen protection, reduce the temperature to -70 to -50°C. Under a catalytic environment, stir and control the temperature to -50 to -40°C. After the addition is complete, keep the temperature to react for 2-3 hours, then heat to room temperature for 12-18 hours to obtain a mixture A. (2) At -75 to -60°C, add tetrahydrofuran to a phenyl-containing phosphonate and stir evenly, then add dropwise to mixture A. After the addition is complete, adjust the temperature, react for 2 to 3 hours, then raise the temperature to room temperature and continue the reaction for 4 to 6 hours; (3) The mixture after the reaction in step (2) was cooled to 0-5°C, diluted hydrochloric acid was added dropwise to quench the reaction, stirred for 3-5 minutes, and allowed to stand for stratification; the aqueous phase was extracted again, the organic phases were combined, washed, and dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to obtain a crude oily product, which was purified by silica gel column to obtain the target compound; The phenyl-containing phosphonate includes at least one of ethyl phenylphosphonate, ethyl diphenylphosphonate, ethyl 2,4,6-trimethylbenzoylphenylphosphonate and ethyl 3-carbonyl-4-(triphenylphosphine)butyrate.

2. The method for synthesizing a blue light hole blocking material based on a dibenzofuran group according to claim 1, characterized in that: The molar ratio of the dibenzofuran and the phenyl-containing phosphonate is 1:(0.9-1.2).

3. The method for synthesizing a blue light hole blocking material based on a dibenzofuran group according to claim 1, characterized in that: In the step (1), the catalytic environment is to add n-butyl lithium or a mixture of n-butyl lithium and 1,4-diazabicyclo[2.2.2]octane into the system.

4. The method for synthesizing a blue light hole blocking material based on a dibenzofuran group according to claim 3, characterized in that: The mass ratio of n-butyl lithium to 1,4-diazabicyclo[2.2.2]octane is 1:(0.5-0.8).

5. The method for synthesizing a blue light hole blocking material based on a dibenzofuran group according to claim 1, characterized in that: The temperature adjusted in step (2) is -55 to -45°C.

6. The method for synthesizing a blue light hole blocking material based on a dibenzofuran group according to claim 1, characterized in that: The specific extraction operation in step (3) is: adding ethyl acetate, stirring, standing, and collecting the organic phase.

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