Method and device for preparing D-A type thermal activation delayed fluorescence material through continuous flow

Abstract

The invention discloses a method and a device for preparing a D-A type thermally activated delayed fluorescent material through continuous flow. A two-section type continuous flow reaction system is adopted, wherein the first continuous flow reaction system is connected with a tubular reactor in series through a micro-channel reactor, and efficient nucleophilic substitution reaction of an electron acceptor halide and an electron donor is achieved under palladium catalysis; the second continuous flow reaction system is driven by double feeding pumps, so that a D-A type compound prepared from a precursor and nonaphenyl tertiary alcohol are subjected to Friedel-Crafts alkylation modification under the catalysis of acid, the reaction time of the two steps is greatly shortened, and the yields of the two steps are both 88% or above. Through flow rate limitation, solvent concentration, solid content and temperature-pressure cooperative control, the problems of palladium-containing catalyst slurry transmission and side reaction inhibition are solved. According to the method, continuous kilogram-level production of the TADF material is achieved, compared with a traditional process, energy consumption is reduced, intermediate separation is not needed, and a new normal form is provided for industrial preparation of the OLED material.

Description

Technical Field

[0001] This invention belongs to the field of fine materials synthesis technology, specifically relating to a method and apparatus for continuous flow preparation of DA-type thermally activated delayed fluorescence materials. Background Technology

[0002] In 1987, Ching-Yun Tang and his team first published the double-layer sandwich structure of organic light-emitting diodes (OLEDs). This technology, with its high brightness, low driving voltage, and high efficiency, opened a new chapter in the field of display technology. With the rapid development of OLED technology, the emitter, the most crucial factor determining OLED efficiency, has undergone two generations of iteration. First-generation fluorescent materials, due to inherent limitations, could only utilize singlet excitons, limiting the theoretical internal quantum efficiency (IQE) of the light-emitting device to 25%. To further improve exciton utilization, in 1998, Yu-Guang Ma et al. and Forrest's research group reported phosphorescent materials based on osmium and platinum metal complexes, respectively. These materials enhanced spin-orbit coupling through the heavy atom effect, achieving comprehensive utilization of both singlet and triplet excitons, enabling a theoretical IQE of 100%. However, the use of precious metals led to high costs, environmental pollution, and device stability issues caused by triplet-triplet annihilation (TTA) in phosphorescent materials, limiting their further commercialization. Pure organic thermally activated delayed fluorescence (TADF) materials can absorb ambient heat to undergo reverse system crossing (RISC), causing excitons to upconvert from T1 to S1, thus achieving 100% exciton utilization. The light emitted after the T1-state exciton transitions to the S1 state via RISC and is radiatively inactivated is called delayed fluorescence. These pure organic TADF materials, combining the low cost of traditional organic fluorescent materials with the high efficiency of noble metal phosphors, are considered third-generation OLED light-emitting materials. Although OLEDs based on TADF materials offer advantages such as high device efficiency and low fabrication cost, they typically involve complex fabrication processes and relatively low yields. Summary of the Invention

[0003] To overcome the above shortcomings, the present invention provides a method and apparatus for preparing DA-type thermally activated delayed fluorescence materials in a continuous flow.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An apparatus for the continuous flow preparation of DA-type thermally activated delayed fluorescent materials includes a first continuous flow reaction system for performing a coupling reaction between an electron acceptor and an electron donor, and a second continuous flow reaction system for performing a Friedel-Crafts alkylation reaction. The first continuous flow reaction system includes a slurry pump, a first microchannel reactor, and a tubular reactor arranged in series. The second continuous flow reaction system includes a first feed pump, a second feed pump, and two second microchannel reactors, wherein the first feed pump and the second feed pump are respectively connected to the two second microchannel reactors, and the two second microchannel reactors are connected in series.

[0005] Further optimization involves using 316L stainless steel for the tubular reactor, with a length of 2 to 20 meters, an inner diameter of ≤6 mm, and a length-to-diameter ratio of ≥100:1.

[0006] Further optimization is achieved by setting the slurry pump's delivery pressure to 0.5 ~ 3MPa and its tolerance to solid-liquid mixture viscosity ≤500cP.

[0007] A method for preparing DA-type thermally activated delayed fluorescent materials via continuous flow, wherein the preparation method is carried out sequentially in a first continuous flow reaction system and a second continuous flow reaction system, and the specific steps are as follows: Step 1: In the first continuous flow reaction system, the electron acceptor, electron donor, palladium catalyst, phosphate and sodium tert-butoxide containing halogenated aromatic hydrocarbons are dissolved in an organic solvent to form a slurry with a solid content ≤10 wt%. The slurry is pumped into the first microchannel reactor and tubular reactor in series system and reacted for 5 to 10 minutes at a temperature of 120~150℃ and a pressure of 0.1~1MPa to generate DA-type TADF compounds. Step 2: In the second continuous flow reaction system, nonaphenyl tertiary alcohol, DA-type TADF compound dissolved in organic solvent, and acid catalyst are fed into the second microchannel reactor through the first feed pump and the second feed pump, respectively. Friedel-Crafts alkylation reaction is carried out at 25~60℃ and 0.1~3.0MPa to obtain a crude product containing sterically hindered groups. Step 3: The crude product is purified by solvent removal, extraction and recrystallization to obtain the DA-type TADF compound containing sterically hindered groups.

[0008] Further optimization is made by using one or more of the following organic solvents in step one: 1,2-dichloroethane, N,N-dimethylacetamide, dimethyl sulfoxide, chlorobenzene, 1,2-dichlorobenzene, dichlorobenzene, nitrobenzene, nitromethane, acetonitrile, carbon tetrachloride, toluene, and o-xylene.

[0009] Further optimization is achieved by using a molar concentration of electron acceptor of 0.05~0.5 mol / L in step one, and a molar ratio of electron acceptor, electron donor, palladium catalyst, phosphate and sodium tert-butoxide of 1:1~1.2:0.02~0.05:1.2~1.5:0.04~0.06.

[0010] Further optimization involves the electron acceptor in step one being one of cyano, pyrimidine, triazine, phosphooxy, or carbonyl derivatives, and the electron donor being one of aniline, acridine, phenoxazine, phenothiazine, or their derivatives.

[0011] Further optimization involves setting the molar ratio of crude product, tertiary alcohol, and acid catalyst in step two to 1:1~1.2:6~10, with the acid catalyst being trifluoromethanesulfonic acid or methanesulfonic acid.

[0012] To further optimize, the extractant used in step three is a deionized water / ethyl acetate / dichloromethane system.

[0013] The beneficial effects of this invention are as follows: 1. A microchannel reactor and a tubular reactor are connected in series to achieve efficient activation of haloaromatics. The electron acceptor and electron donor of the haloaromatics undergo nucleophilic substitution reactions under the action of palladium catalyst to form DA-type TADF materials. Subsequently, the material is further modified in the microchannel reactor by using the sterically hindered group nonaphenyl tertiary alcohol under the action of acid catalyst via Friedel-Crafts reaction. The sterically hindered group inhibits intermolecular π-π stacking through steric hindrance, improving the fluorescence quantum yield to over 88%. 2. The continuous flow reaction system has excellent mass and heat transfer efficiency and better mixing conditions for reactants, which greatly shortens the reaction time and greatly improves the reaction efficiency. The substitution reaction is shortened from 12-24 hours to 5-10 minutes, and the Friedel-Crafts reaction is shortened from 2-8 hours to less than 1 minute. It can also continuously discharge materials, has a high degree of automation, can reduce manual operation, and facilitate intelligent production. In summary, this method can significantly shorten the preparation time of TADF materials, and the automation and efficiency of the preparation process are significantly improved, energy consumption is greatly reduced, safety is greatly enhanced, and there is no scale-up effect, making it easy to apply in industrial applications. Attached Figure Description

[0014] Figure 1 A flowchart and schematic diagram of the synthesis apparatus for the continuous flow preparation of DA-type TADF compounds; Figure 2 A flowchart and schematic diagram of the synthesis apparatus for the continuous flow preparation of crude products containing sterically hindered groups; Reference numerals: 1. Slurry pump; 2. First microchannel reactor; 3. Tubular reactor; 4. First feed pump; 5. Second feed pump; 6. Second microchannel reactor. Detailed Implementation

[0015] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be described in detail below with reference to specific embodiments. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operation processes. However, the present invention can also be implemented in other ways different from those described herein, so the scope of protection of the present invention is not limited to the following embodiments.

[0016] An apparatus for the continuous flow preparation of DA-type thermally activated delayed fluorescent materials includes a first continuous flow reaction system and a second continuous flow reaction system. The first continuous flow reaction system includes a slurry pump 1, a first microchannel reactor 2 and a tubular reactor connected in series, and the second continuous flow reaction system includes a dual feed pump and a second microchannel reactor 6.

[0017] In the first continuous flow reaction system, an electron acceptor, electron donor, palladium catalyst, phosphate, and sodium tert-butoxide of a halogenated aromatic hydrocarbon (-F, -Br) are added to an organic reagent in a molar ratio of 1:1~1.2:0.02~0.05:1.2~1.5:0.04~0.06 to form a mixture. The electron acceptor is one of cyano, pyrimidine, triazine, phosphooxy, or carbonyl derivatives, and the electron donor is one of carbazole, aniline, acridine, phenoxazine, phenothiazine, or their derivatives. The organic solvent is one or more of 1,2-dichloroethane, N,N-dimethylacetamide, dimethyl sulfoxide, chlorobenzene, 1,2-dichlorobenzene, dichlorobenzene, nitrobenzene, nitromethane, acetonitrile, carbon tetrachloride, toluene, and o-xylene, with a concentration of 0.05~0.5 mol / L. The solid content of the mixed feedstock does not exceed 10 wt% to prevent feed system collapse and microreactor blockage.

[0018] The raw material is fed into the first microchannel reactor 2 via a single-stream feed pump 1 at a flow rate of 30-60 ml / min and a residence time of 5-10 min. During the reaction, the back pressure is 0.1-1 MPa, and the reaction temperature is 120-150℃. Specifically, in this reaction, an electron-acceptor halide (RCX) serves as the substrate, and the electron donor, acting as a nucleophile, attacks the CX bond, thereby replacing the halogen atom to form a DA-type TADF compound. After the reactants exit the first microchannel reactor 2, they are extracted and recrystallized to obtain the DA-type TADF compound.

[0019] In the second continuous flow reaction system, nonaphenyl tertiary alcohol dissolved in the solvent is used as material A and is fed into the module preheating of the second microchannel reactor 6 through the first feed pump 4 of the dual-feed pump. Subsequently, the product DA-type TADF compound and the acid catalyst are added to the organic solvent as material B and mixed in the second microchannel reactor 6 through the second feed pump 5 of the dual-feed pump, and a Friedel-Crafts alkylation reaction occurs. After the reactants flow out of the second microchannel reactor 6, the solvent is removed by vacuum distillation or rotary evaporation. The crude product is obtained by extraction using a deionized water / ethyl acetate / dichloromethane system, and then recrystallized to obtain the target product, a DA-type TADF compound containing sterically hindered groups.

[0020] The molar ratio of the product DA-type TADF compound, nonaphenyl tertiary alcohol, and acid catalyst is 1:1~1.2:6~10; the acid catalyst is one or more of methanesulfonic acid, boron trifluoride ethyl ether, trifluoromethanesulfonic acid, hydrochloric acid, and Eaton reagent; the solvent is one or more of dichloromethane, 1,2-dichloroethane, 1,2-dichlorobenzene, dichlorobenzene, nitrobenzene, nitromethane, acetonitrile, trichloromethane, carbon tetrachloride, bromobenzene, or dibromobenzene; the temperature in the microchannel reactor is controlled within the range of 25~60℃; the flow rates of feed pump 1 and feed pump 2 are the same and controlled within the range of 20~50 ml / min; the back pressure during the reaction is 0.1~3.0 MPa.

[0021] Example 1 In the first continuous flow reaction system, 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (8.8 g, 27.18 mmol), carbazole (5 g, 29.9 mmol), palladium acetate (0.18 g, 0.82 mmol), sodium tert-butoxide (3.13 g, 32.62 mmol), and tritert-butylphosphine tetrafluoroborate (0.47 g, 1.63 mmol) were added to a mixed solvent prepared from 150 ml of N,N-dimethylacetamide and 150 ml of o-xylene, forming a turbid liquid. The reactants were evacuated and then supplied with nitrogen, followed by feeding into the first microchannel reactor 2. A slurry pump 1 was used to pump the slurry into the first microchannel reactor 2 at a rate of 3 L / h, with the temperature controlled at 150 °C and a residence time of 369 s. The resulting material was subjected to vacuum distillation to remove high-boiling-point solvents, followed by the addition of dichloromethane and water. After adjusting the pH to neutral, extraction was performed, and the organic phase was rotary evaporated. Recrystallization of the crude product from ethanol yielded 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-carbazole (CzTRZ) with a yield of 91% and a purity of 97%. In this reaction system, an electron-acceptor halide (RCX) acts as the substrate, and the electron donor, acting as a nucleophile, attacks the CX bond, thereby replacing the halogen atom to form a DA-type TADF compound. The structural formula of CzTRZ is as follows: .

[0022] In the second continuous flow reaction system, nonaphenyl tert-ol (6.2 g, 24 mmol) was dissolved in 250 ml of dichloromethane as feed A, and CzTRZ (5.45 g, 11.48 mmol) and methanesulfonic acid (11.05 g, 114.97 mmol) were dissolved in 250 ml of dichloromethane as feed B. Feed A was fed into the second microchannel reactor 6 at a flow rate of 25 ml / min via the first feed pump 4 and preheated to 40°C. Subsequently, feed B was fed into the second microchannel reactor 6 at a flow rate of 25 ml / min via the second feed pump 5 and mixed with feed A. The reaction temperature was 40°C and the residence time was 58 s. The effluent was quenched with a large amount of water and the pH was adjusted to neutral using sodium bicarbonate. The crude product was obtained by extraction and rotary evaporation. Recrystallization from ethanol yielded the target product 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-3,6-triphenylmethyl-9H-carbazole (DPFCzTRZ) in 95% yield and 98% purity. The structural formula is as follows: .

[0023] Example 2 In the first continuous flow reaction system, 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (8.8 g, 27.18 mmol), acridine (6.26 g, 29.9 mmol), palladium acetate (0.18 g, 0.82 mmol), sodium tert-butoxide (3.13 g, 32.62 mmol), and tritert-butylphosphine tetrafluoroborate (0.47 g, 1.63 mmol) were added to a mixed solvent prepared from 150 ml of N,N-dimethylacetamide and 150 ml of o-xylene, forming a turbid liquid. The reactants were evacuated and then supplied with nitrogen, followed by connection to a microchannel reactor. A slurry pump was used to pump the slurry into the microchannel reactor at a rate of 3 L / h, with the temperature controlled at 150 °C and a residence time of 369 s. The resulting material was subjected to vacuum distillation to remove high-boiling-point solvents, followed by the addition of dichloromethane and water. After adjusting the pH to neutral, extraction was performed, and the organic phase was rotary evaporated. The crude product was recrystallized from ethanol to yield 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (DMACTRZ) in 92% yield and 97% purity. In this reaction system, an electron-acceptor halide (RCX) acts as the substrate, and the electron donor, acting as a nucleophile, attacks the CX bond, thereby replacing the halogen atom to form a DA-type TADF compound. The structure of DMACTRZ is as follows: .

[0024] In the second continuous flow reaction system, nonaphenyl tert-ol (5.97 g, 23.1 mmol) was dissolved in 250 ml of dichloromethane as feed A, and DMACTRZ (5.68 g, 11 mmol) and methanesulfonic acid (10.57 g, 110 mmol) were dissolved in 250 ml of dichloromethane as feed B. Feed A was fed into the second microchannel reactor 6 at a flow rate of 25 ml / min via the first feed pump 4 and preheated to 40°C. Subsequently, feed B was fed into the second microchannel reactor 6 at a flow rate of 25 ml / min via the second feed pump 5. The reaction temperature was 40°C and the residence time was 58 s. The effluent was quenched with a large amount of water and the pH was adjusted to neutral using sodium bicarbonate. The crude product was obtained by extraction and rotary evaporation. Recrystallization from ethanol yielded the target product 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-2,7-di-tert-butyl-9,10-dihydroacridine (DPFDMACTRZ) in 96% yield and 98% purity. The structure of DPFDMACTRZ is as follows: .

[0025] Comparative Example 1 The prepared samples were consistent with those in Example 1, except that the comparative CzTRZ and DPFCZTRZ were prepared in reaction flasks. First, a 250 mL two-necked flask, a magnetic stir bar, and a spherical condenser were prepared and the apparatus assembled. 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (6 g, 18.3 mmol), carbazole (3.1 g, 18.3 mmol), and potassium carbonate (10 g, 76.25 mmol) were added to the reaction flask in the specified ratio, and the apparatus was sealed. The apparatus was evacuated and then replenished with nitrogen, circulated 3-4 times. The apparatus was then placed in an oil bath, and the N,N-dimethylformamide phase was injected into the reaction flask. The system was reacted at 150°C with stirring for 12 hours, after which the reaction was stopped. The reaction was quenched with water, extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered, rotary evaporated, and subjected to column chromatography (silica gel 200-300 mesh, eluent: V). 石油醚 / V 二氯甲烷 = 2 / 1) yielded the pale yellow compound CZTRZ (6.5 g, 74.7%). CzTRZ (1 g, 3.90 mmol) and boron trifluoride diethyl ether (0.52 mL) dissolved in anhydrous dichloromethane (60 mL) were added to a reaction flask. PFOH (2.21 g, 8.58 mmol) in 60 mL of anhydrous dichloromethane was added through a constant-pressure dropping funnel, followed by the addition of the solvent from the constant-pressure dropping funnel to the reaction flask. The reaction was carried out in a 500 mL double-necked round-bottom flask. After reacting at 40 °C for 5 hours, water (100 mL) was added to quench the reaction. The mixture was separated, and the aqueous phase was extracted with dichloromethane. The combined organic layers were washed with brine and dried over anhydrous magnesium sulfate. After removing the solvent, the crude product was purified by column chromatography using a petroleum ether:dichloromethane (6:1) eluent to give a pale yellow solid product DPFCzTRZ (2.1 g, 57.4%).

[0026] In summary, the use of microchannel reactors and tubular reactors significantly shortens the preparation time of TADF materials, and the automation and efficiency of the preparation process are significantly improved, resulting in a marked increase in the yield of the target product.

[0027] A microchannel reactor connected in series with a tubular reactor achieves efficient activation of haloaromatics. Electron acceptors and donors of haloaromatics undergo nucleophilic substitution reactions under palladium catalysis to form DA-type TADF materials. Subsequently, the material is further modified in the microchannel reactor using a sterically hindered group, nonaphenyl tertiary alcohol, via a Friedel-Crafts reaction under acid catalysis. The σ-π conjugated 9-phenyl-9-fluorenyl substituent enhances horizontal molecular orientation and increases the photoluminescence quantum yield to over 88%.

[0028] The preparation method in this invention features high raw material conversion rate, simple and rapid product processing, and significantly optimized post-processing, reducing operation time and labor intensity, and substantially lowering production costs. Currently, luminescent materials are iterating rapidly, and continuous flow reactors offer "numerical scaling-up" without scale-up effects, enabling seamless transition from laboratory to industrial production. This allows for rapid response to market conditions, reducing project implementation and operational risks.

[0029] The foregoing has shown and described the main features, usage methods, basic principles, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention based on actual circumstances without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An apparatus for continuous flow preparation of DA-type thermally activated delayed fluorescence materials, characterized in that, The system includes a first continuous flow reaction system for performing a coupling reaction of an electron acceptor and an electron donor, and a second continuous flow reaction system for performing a Friedel-Crafts alkylation reaction. The first continuous flow reaction system includes a slurry pump (1), a first microchannel reactor (2), and a tubular reactor (3) arranged in series. The second continuous flow reaction system includes a first feed pump (4), a second feed pump (5), and two second microchannel reactors (6). The first feed pump (4) and the second feed pump (5) are respectively connected to the two second microchannel reactors (6), and the two second microchannel reactors (6) are connected in series.

2. The apparatus for continuous flow preparation of DA-type thermally activated delayed fluorescence materials as described in claim 1, characterized in that, The tubular reactor (3) is made of 316L stainless steel, with a length of 2 to 20m, an inner diameter of ≤6mm, and a length-to-diameter ratio of ≥100:

1.

3. The apparatus for continuous flow preparation of DA-type thermally activated delayed fluorescence materials as described in claim 1, characterized in that, The slurry pump (1) has a delivery pressure of 0.5 ~ 3MPa and can withstand a solid-liquid mixture viscosity of ≤500cP.

4. A method for preparing DA-type thermally activated delayed fluorescence materials using any one of the apparatuses described in claims 1-3, characterized in that, The preparation method is carried out sequentially in a first continuous flow reaction system and a second continuous flow reaction system, and the specific steps are as follows: Step 1: In the first continuous flow reaction system, the electron acceptor, electron donor, palladium catalyst, phosphate and sodium tert-butoxide containing halogenated aromatic hydrocarbons are dissolved in an organic solvent to form a slurry with a solid content ≤10 wt%. The slurry is then pumped into the first microchannel reactor (2) and the tubular reactor (3) in series via a slurry pump (1) and reacted for 5 to 10 minutes at a temperature of 120~150℃ and a pressure of 0.1~1MPa to generate DA-type TADF compounds. Step 2: In the second continuous flow reaction system, nonaphenyl tertiary alcohol is fed into the second microchannel reactor (6) through the first feed pump (4), DA-type TADF compound dissolved in organic solvent and acid catalyst are fed into the second feed pump (5), and Friedel-Crafts alkylation reaction is carried out at 25~60℃ and 0.1~3.0MPa to obtain crude product containing sterically hindered groups; Step 3: The crude product is purified by solvent removal, extraction and recrystallization to obtain the DA-type TADF compound containing sterically hindered groups.

5. The method for preparing DA-type thermally activated delayed fluorescence material in a continuous flow process as described in claim 4, characterized in that, The organic solvent in step one is one or more of the following: 1,2-dichloroethane, N,N-dimethylacetamide, dimethyl sulfoxide, chlorobenzene, 1,2-dichlorobenzene, dichlorobenzene, nitrobenzene, nitromethane, acetonitrile, carbon tetrachloride, toluene, and o-xylene.

6. The method for preparing DA-type thermally activated delayed fluorescence material in a continuous flow process as described in claim 4, characterized in that, In step one, the molar concentration of the electron acceptor is 0.05~0.5 mol / L, and the molar ratio of the electron acceptor, electron donor, palladium catalyst, phosphate and sodium tert-butoxide is 1:1~1.2:0.02~0.05:1.2~1.5:0.04~0.

06.

7. The method for preparing DA-type thermally activated delayed fluorescent materials in a continuous flow process as described in claim 4, characterized in that, In step one, the electron acceptor is one of cyano, pyrimidine, triazine, phosphooxy, or carbonyl derivatives, and the electron donor is one of aniline, acridine, phenoxazine, phenothiazine, or their derivatives.

8. The method for preparing DA-type thermally activated delayed fluorescence material in a continuous flow process as described in claim 4, characterized in that, In step two, the molar ratio of crude product, tertiary alcohol, and acid catalyst is 1:1~1.2:6~10, and the acid catalyst is trifluoromethanesulfonic acid or methanesulfonic acid.

9. The method for preparing DA-type thermally activated delayed fluorescence material in a continuous flow process as described in claim 4, characterized in that, The extractant used in step three is a deionized water / ethyl acetate / dichloromethane system.

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