A thienyl covalent triazine framework material, a preparation method thereof and application thereof in photocatalytic preparation of benzimidazole

Abstract

This invention relates to the preparation of a thiophene-based covalent triazine framework material with a cascade effect and its application in the green photocatalytic conversion of benzimidazole derivatives. Specifically, this invention belongs to the field of organic porous materials and photocatalysis technology, and relates to the design and synthesis method of a novel covalent triazine framework material, as well as its application as a highly efficient and recyclable photocatalyst driving organic conversion reactions under mild conditions. This invention employs an acid-catalyzed trimerization reaction to successfully construct a covalent triazine framework material based on thiophene units (named PhTh-CTF). Using benzo[b]thiophene-2,5-dicyano as a single precursor and trifluoromethanesulfonic acid as a catalyst and reaction medium, a covalent organic framework with triazine ring connecting units is constructed through the trimerization cyclization reaction of the cyano group. This material exhibits a significant cascade effect.

Description

Technical Field

[0001] This invention pertains to the preparation of covalent triazine framework materials and their application in the field of photocatalytic organic conversion, specifically relating to a method for preparing a thiophene covalent triazine framework material with a cascade effect and its application. This method employs an acid-catalyzed trimerization reaction, using benzothiophene as the building block, to successfully prepare a covalent triazine framework material with a cascade effect. Background Technology

[0002] Benzimidazole and its derivatives, as an important class of nitrogen-containing heterocyclic compounds, have broad application prospects in medicinal chemistry, materials science, and other fields, and their efficient and green synthetic methods have attracted much attention. From an energy perspective, traditional organic synthesis mostly relies on harsh reaction conditions such as high temperature and high pressure, and often requires the consumption of large amounts of non-renewable fossil fuels to drive the reaction. At the same time, the chemical oxidants commonly used in traditional organic reactions, such as heavy metal salts and peroxides, are not only costly, but also generate a large amount of toxic and harmful waste, causing serious pollution to the soil, water bodies, and other ecological environments.

[0003] In recent years, with the continuous advancement of sustainable development strategies, utilizing clean and renewable energy to drive organic reactions has become an inevitable trend. Solar energy, as the most abundant renewable energy source on Earth, is clean, pollution-free, and inexhaustible, making it an ideal energy source. Photocatalysis technology uses clean light energy as a driving force to accelerate reaction processes with photocatalysts. This process combines advantages such as mild reaction conditions and environmental friendliness, demonstrating enormous potential in addressing energy shortages and environmental pollution problems.

[0004] Among numerous photocatalytic materials, covalent triazine frameworks (CTFs) have attracted considerable attention due to their unique structural properties. CTFs are triazine ring structures composed of strong covalent bonds, exhibiting excellent thermal stability, high structural designability, and good light-harvesting and carrier generation capabilities. Studies have shown that CTFs can utilize their nitrogen-rich structure to provide abundant active sites, while simultaneously increasing reaction contact through their large specific surface area, thereby synergistically promoting photocatalytic performance. However, traditional CTF materials suffer from insufficient separation efficiency of photogenerated electrons and holes, and a relatively fast recombination rate, resulting in an insufficient number of effective carriers actually participating in the catalytic reaction, severely limiting quantum efficiency and reaction rate.

[0005] To address the aforementioned problems, this invention designs a thiophene-based covalent triazine framework material with a cascade effect, using benzothiophene as the building block. By introducing benzothiophene as the electron donor unit and the triazine ring as the electron acceptor unit, a cascade structure is constructed, effectively promoting the separation and migration of photogenerated electron-hole pairs, thereby improving photocatalytic efficiency. This material can efficiently catalyze the organic conversion synthesis of benzimidazole compounds under visible light irradiation, overcoming the limitations of traditional CTFs such as fast carrier recombination rates, and providing a new technical solution for green organic synthesis. Summary of the Invention

[0006] The purpose of this invention is to reduce the high recombination efficiency of traditional CTFs, improve charge separation efficiency, and synthesize benzimidazole and its derivatives under mild conditions. Firstly, a covalent triazine framework material with benzothiophene as the basic unit was prepared via polycondensation.

[0007] Thiophene-based covalent triazine framework materials exhibiting cascade effects, wherein the covalent triazine framework materials comprise 1509 cm⁻¹ -1 -1360 cm -1 There is an infrared absorption peak at the C=N bond of the triazine ring; the solid-state 13C-CPNMR spectrum shows a relatively broad signal in the range of 180 to 160 ppm, which is attributed to the sp² carbon atom in the triazine unit that connects the thiophene or phenyl unit.

[0008] The material uses thiophene-based cyano compounds as a single building block precursor, and forms a covalent organic framework structure with triazine rings through a cyano trimerization reaction. The thiophene unit is benzothiophene or alkyl / aryl substituted thiophene.

[0009] This invention also provides a method for preparing a thiophene-based covalent triazine framework material with a cascade effect. The cascade effect in PhTh-CTF promotes the separation of photogenerated electrons and holes. A cyano compound is mixed with an acid catalyst and heated under an inert atmosphere and a closed environment to carry out a trimerization reaction. After the reaction, a yellow-brown thiophene-based covalent triazine framework material is obtained through post-treatment. The method includes the following steps:

[0010] In a further preferred embodiment, a certain amount of cyano compound is weighed, a certain amount of acid catalyst is added, and the mixture is heated to 80-150℃ under a N2 atmosphere for 1-5 days. After the reaction is complete, the mixture is washed with an organic reagent and dried overnight at 60-80℃ to obtain a brownish-yellow covalent triazine framework (PhTh-CTF) powder sample with benzothiophene as the building block.

[0011] The cyano compounds include: benzo[b]thiophene-2,5-dicyano, 5-(4-cyanophenyl)thiophene-2-carboxynitrile, and 2,5-dicyanothiophene; the acid catalysts include: zinc chloride, trifluoromethanesulfonic acid, trimethylsilyl trifluoromethanesulfonate, aluminum chloride, titanium tetrachloride, or methanesulfonic acid; wherein the cyano compound is preferably benzo[b]thiophene-2,5-dicyano; and the acid catalyst is preferably trifluoromethanesulfonic acid.

[0012] The reaction temperature is 80-150℃, preferably 100℃, and the reaction time is 1-5 days, preferably 3 days.

[0013] The preparation method further includes post-treatment, which includes: cooling the reaction product to room temperature and then adding dilute ammonia water to neutralize it (pH=9), filtering it, washing the filter residue sequentially with ultrapure water, low-carbon alcohol, and ketone organic solvent, and finally vacuum drying to obtain the target product; wherein the low-carbon alcohol is methanol or ethanol, and the ketone organic solvent is acetone.

[0014] The present invention also provides a catalyst for the photocatalytic preparation of benzimidazole and its derivatives, wherein the catalyst is a covalent triazine framework material with benzothiophene as the building block and exhibiting a cascade effect.

[0015] The method for preparing benzimidazole and its derivatives by photocatalysis includes the following steps: First, a certain amount of o-phenylenediamine, benzaldehyde and its derivatives, and PhTh-CTF photocatalyst were weighed into a light-transmitting glass bottle. Then, a certain volume of reaction solvent was measured and fully dissolved. Next, a certain amount of gas was introduced to maintain the stability of the reaction system. The glass bottle was placed under a light source and stirred for a certain period of time at a specific temperature. After the experiment, the reaction system was processed, the products were collected and analyzed to determine the success of the reaction and the catalytic effect of the catalyst. The reaction formula is as follows:

[0016] R1 is any one of alkyl, alkoxy, or halogen; R2 is any one of alkyl, alkoxy, or halogen; The alkyl group is C1-C 10 The alkoxy group is a straight-chain alkane or a branched-chain alkane; the alkoxy group includes one of methoxy, ethoxy, or propoxy; and the halogen is any one of F, Cl, Br, or I.

[0017] The molar ratio of the o-phenylenediamine substrate to the benzaldehyde substrate is 1:1; the amount of catalyst used is 1% to 10% of the total mass of the o-phenylenediamine substrate and the benzaldehyde substrate; the organic solvent includes any one of dimethyl sulfoxide, acetone, acetonitrile, dichloromethane, methanol, ethanol, and N,N-dimethylformamide.

[0018] The oxygen-containing atmosphere is air or pure oxygen, preferably pure oxygen; the oxidant is a species that can generate highly reactive oxygen species during organic conversion reactions and intervene in the aerobic organic reaction process.

[0019] The visible light is emitted by ultraviolet LEDs, blue LEDs, white LEDs, green LEDs, or orange LEDs, preferably blue light emitted by blue LEDs; the stirring reaction at room temperature takes 6 to 24 hours, preferably 12 hours.

[0020] The reaction also includes a post-processing step, which includes filtration, extraction, and column chromatography separation; the catalyst obtained by filtration can be directly recycled after washing and vacuum drying.

[0021] After obtaining benzimidazole and its derivatives, PhTh-CTF was recovered, reactivated, and the preparation of benzimidazole and its derivatives was repeated to achieve... N Preparation in multiple cycles. N Greater than or equal to 3.

[0022] The specific beneficial effects of this material are manifested as follows: (1) By this method, a covalent triazine framework with cascade effect and benzothiophene as the building unit can be successfully prepared, and the traditional high-temperature molten salt polycondensation is replaced by low-temperature catalysis of superacid.

[0023] (2) The benzothiophene unit has strong conjugation and electron-donating ability. After it is introduced into the triazine framework, it exhibits higher photocurrent response and lower carrier recombination rate under visible light irradiation through intramolecular charge transfer effect.

[0024] (3) It maintains high catalytic activity and low catalyst loss in multiple cycles and has good stability.

[0025] (4) In this invention, blue light is used as the light source and the covalent triazine framework PhTh-CTF linked to benzothiophene is used as the photocatalyst to perform photocatalytic aerobic oxidation of o-phenylenediamine and benzaldehyde and its derivatives to benzimidazole and its derivatives. The yield of benzimidazole and its derivatives can reach more than 70%, showing good photocatalytic activity.

[0026] (4) The introduction of the benzo[b]thiophene unit modulates the band structure of the triazine framework, making it more inclined to selectively generate singlet oxygen or superoxide radicals through energy transfer or single electron transfer pathways under photoexcitation. This solves the problem that traditional photocatalysts are prone to excessive oxidation of benzaldehyde due to poor selectivity of active oxygen species during oxidative coupling. Attached Figure Description

[0027] Figure 1 This is a synthesis route diagram for PhTh-CTF materials.

[0028] Figure 2 The Fourier transform infrared spectra of PhTh-CTF materials and their monomers are shown.

[0029] Figure 3 The solid-state NMR spectrum of PhTh-CTF material.

[0030] Figure 4 This is the 1H NMR spectrum of benzimidazole.

[0031] Figure 5 The NMR spectrum of 5,6-dimethyl-2-phenyl-1H-benzo[d]imidazolium is a 1H NMR spectrum.

[0032] Figure 6 The NMR spectrum of 5,6-dichloro-2-phenyl-1H-benzo[d]imidazolium is a 1H NMR spectrum.

[0033] Figure 7 The 1H NMR spectrum of 2-(4-methoxyphenyl)-1H-benzo[d]imidazolium is shown.

[0034] Figure 8 The 1H NMR spectrum of 2-(4-fluorophenyl)-1H-benzo[d]imidazolium is shown.

[0035] Figure 9 Cyclic stability test results for PhTh-CTF material with a covalent triazine framework.

[0036] Figure 10 Fourier transform infrared spectra of PhTh-CTF before and after cycling. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0038] Example 1 100 mg of benzo[b]thiophene-2,5-dicyano was added to a 10 mL test tube, and 2 mL of trifluoromethanesulfonic acid was added as a catalyst under a nitrogen atmosphere. The mixture was then stirred at 80 °C for 24 hours under a nitrogen atmosphere. After the reaction was complete, it was allowed to cool to room temperature. Dilute ammonia (pH=9) was added first, followed by filtration. The filter residue was then washed 3-6 times sequentially with ultrapure water, ethanol, and acetone. Finally, the obtained sample was dried at 60 °C under vacuum; PhTh-CTF material was not obtained.

[0039] Example 2 Synthesis of benzimidazole:

[0040] Weigh 0.2 mmol of o-phenylenediamine and 0.2 mmol of benzaldehyde, and then weigh 5 mg of photocatalyst (PhTh-CTF-1) into a light-transmitting glass bottle. Add 2 mL of MeOH, and purge with a certain amount of N2 (5 mL / min). Under blue light, stir the glass bottle at room temperature for 12 h to obtain a small amount of benzimidazole product. (15 mg, 40%, separation yield) Weigh 0.2 mmol o-phenylenediamine and 0.2 mmol benzaldehyde, add 2 mL MeOH, and under catalyst-free conditions, introduce a certain amount of O2 (5 mL / min). Stir the glass bottle at room temperature for 12 h under blue light to obtain a small amount of benzimidazole product (15 mg, 40%, separation yield).

[0041] Weigh 0.2 mmol o-phenylenediamine and 0.2 mmol benzaldehyde, add 2 mL MeOH, then weigh 5 mg photocatalyst (PhTh-CTF-1), introduce a certain amount of O2 (5 mL / min), and stir the glass bottle at room temperature for 12 h in the dark to obtain a small amount of benzimidazole product (11.6 mg, 30%, separation yield).

[0042] Weigh 0.2 mmol o-phenylenediamine and 0.2 mmol benzaldehyde, add 2 mL MeCN, then weigh 5 mg photocatalyst (PhTh-CTF), introduce a certain amount of O2 (5 mL / min), stir the glass bottle at room temperature for 12 h under blue light, and obtain a small amount of benzimidazole product (19 mg, 50%, separation yield).

[0043] Weigh 0.2 mmol o-phenylenediamine and 0.2 mmol benzaldehyde, add 2 mL DMF, then weigh 5 mg photocatalyst (PhTh-CTF), introduce a certain amount of O2 (5 mL / min), and stir the glass bottle at room temperature for 12 h under blue light. No benzimidazole product was obtained.

[0044] The above description is merely a poor example of the present invention and is not within the scope of protection of this case, and is a case in which it is difficult to achieve a good yield.

[0045] Example 3 Synthesis of PhTh-CTF: Weigh out 100 mg of benzo[b]thiophene-2,5-dicyano into a 10 mL test tube. Add 2 mL of trifluoromethanesulfonic acid as a catalyst under a nitrogen atmosphere (N2). Stir at 100 °C for 72 hours under a nitrogen atmosphere (N2). After the reaction is complete, allow it to cool to room temperature. First, add dilute ammonia and filter. Then, wash the filter residue 3-6 times successively with ultrapure water, ethanol, and acetone. Finally, dry the obtained sample under vacuum at 60 °C to obtain the final product PhTh-CTF-1.

[0046] Figure 1 This is a synthesis route diagram for PhTh-CTF materials.

[0047] Figure 2 The Fourier transform infrared (FTIR) spectrum of PhTh-CTF material is shown at 1509 cm⁻¹. -1 -1360 cm -1 The infrared absorption peak at the C=N bond of the triazine ring indicates the successful preparation of this material.

[0048] Figure 3 The solid-state NMR spectrum of PhTh-CTF material shows a relatively broad signal in the range of 180 to 160 ppm, which is attributed to the sp24-p- ... 2 The carbon atoms and all other chemical shifts were attributed to the corresponding carbon atoms in the CTFs. This fully demonstrates the successful preparation of the CTF material.

[0049] Example 3-1 100 mg of benzo[b]thiophene-2,5-dicyano was added to a 10 mL test tube, and 2 mL of trimethylsilyl trifluoromethanesulfonate was added as a catalyst under a nitrogen atmosphere. The mixture was then stirred at 100 °C for 72 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature. Dilute ammonia was added first, and the mixture was filtered. The filter residue was then washed 3-6 times with ultrapure water, ethanol, and acetone, respectively. Finally, the obtained sample was dried at 60 °C under vacuum to obtain the final product PhTh-CTF-2.

[0050] Example 4 Synthesis of benzimidazole:

[0051] Weigh 0.2 mmol of o-phenylenediamine and 0.2 mmol of benzaldehyde, and then weigh 5 mg of photocatalyst (PhTh-CTF-1) into a light-transmitting glass bottle. Add 2 mL of MeOH, and pass a certain amount of O2 through the bottle (5 mL / min). Under blue light, stir the glass bottle at room temperature for 12 h to obtain the benzimidazole product (33.7 mg, 87%, separation yield).

[0052] Figure 4 The image shows the 1H NMR spectrum of benzimidazole. 1 ¹H NMR (400 MHz, DMSO-d⁶) δ 12.92 (s, 1H), 8.18 (dd, J = 7.1, 1.8 Hz, 2H), 7.54 (td, J = 17.0, 8.6 Hz, 5H), 7.20 (dd, J=6.0, 3.2 Hz, 2H). The figure shows that we successfully synthesized benzimidazole.

[0053] Example 4-1 Synthesis of 5,6-dimethyl-2-phenyl-1H-benzo[d]imidazole:

[0054] Weigh 0.2 mmol of 4,5-dimethyl-1,2-phenylenediamine and 0.2 mmol of benzaldehyde, and weigh 5 mg of photocatalyst (PhTh-CTF-1) into a light-transmitting glass bottle. Add 2 mL of MeOH and purge with a certain amount of O2 (5 mL / min). Under blue light, stir the glass bottle at room temperature for 12 h to obtain the benzimidazole product (40.5 mg, 70%, separation yield).

[0055] Figure 5 The 1H NMR spectrum of 5,6-dimethyl-2-phenyl-1H-benzo[d]imidazolium is shown. 1 ¹H NMR (500 MHz, DMSO-d⁶) δ 12.62 (s, 1H), 8.14 (dt, J = 6.3, 1.3 Hz, 2H), 7.63 – 7.42 (m, 4H), 7.29 (s, 1H), 2.32 (d, J = 10.4 Hz, 6H); The figure shows that we successfully synthesized 5,6-dimethyl-2-phenyl-1H-benzo[d]imidazole.

[0056] Example 4-2 Synthesis of 2-(4-methoxyphenyl)-1H-benzo[d]imidazole:

[0057] Weigh 0.2 mmol of o-phenylenediamine and p-methoxybenzaldehyde, add 5 mg of photocatalyst (PhTh-CTF-1) to a light-transmitting glass bottle, add 2 mL of MeOH, and pass in a certain amount of O2 (5 mL / min). Place the glass bottle in a blue light reactor and stir at room temperature for 12 h to obtain the 2-(4-methoxyphenyl)-1H-benzo[d]imidazole product.

[0058] Figure 6 The 1H NMR spectrum of 2-(4-methoxyphenyl)-1H-benzo[d]imidazole is shown. 1 ¹H NMR (400 MHz, DMSO-d6) δ 12.75 (s, 1H), 8.11 (d, J = 8.9 Hz, 2H), 7.66–7.45 (m, 2H), 7.20–7.08 (m, 4H), 3.84 (s, 3H); As shown in the figure, we successfully synthesized 2-(4-methoxyphenyl)-1H-benzo[d]imidazole (44.3 mg, 75%, isolated yield).

[0059] Example 4-3 Synthesis of 2-(p-Tolyl)-1H-Benzo[d]imidazole:

[0060] Weigh 0.2 mmol of o-phenylenediamine and p-methylbenzaldehyde, add 5 mg of photocatalyst (PhTh-CTF-1) to a light-transmitting glass bottle, add 2 mL of MeOH, and pass in a certain amount of O2 (5 mL / min). Place the glass bottle in a blue light reactor and stir at room temperature for 12 h to obtain the 2-(p-tolyl)-1H-benzo[d]imidazole product.

[0061] Figure 7 The 1H NMR spectrum of 2-(p-tolyl)-1H-benzo[d]imidazole 1 ¹H NMR (400 MHz, DMSO-d6) δ 8.07 (d, J = 8.1 Hz, 2H), 7.58 (dd, J = 6.0, 3.2 Hz, 2H), 7.38 – 7.18 (m, 4H), 2.38 (s, 3H); As shown in the figure, we successfully synthesized 2-(p-tolyl)-1H-benzo[d]imidazole (40.1 mg, 74% isolated yield).

[0062] Example 5 Cyclic stability test: Using PhTh-CTF as a photocatalyst, the photocatalytic organic conversion reaction of o-phenylenediamine with benzaldehyde and its derivatives was carried out according to the method of Example 3, successfully generating benzimidazole and its derivatives. After the reaction, the PhTh-CTF catalyst was separated from the reaction solution by simple filtration, then thoroughly washed with ethanol, and dried under vacuum at room temperature. The activated PhTh-CTF was then directly used in the next round of reaction. The reaction was repeated at least three times under the conditions of Example 3 to systematically evaluate its cycling stability.

[0063] Figure 9 The graph shows the cyclic stability of PhTh-CTF within the covalent triazine framework. Figure 10 The images show the FT-IR spectra of the covalent triazine framework PhTh-CTF before and after cycling. Experimental results indicate that the PhTh-CTF maintains high photocatalytic activity for the aforementioned reactions after five cycles. Furthermore, the FT-IR of the recovered PhTh-CTF remains essentially unchanged after five cycles, demonstrating the good stability of the PhTh-CTF photocatalyst.

[0064] In summary, this method provides a covalent triazine framework photocatalyst with a cascade effect and its application in photocatalytic organic conversion. The prepared PhTh-CTF was applied to the organic conversion of o-phenylenediamine with benzaldehyde and its derivatives, catalyzing the formation of benzimidazole and its derivatives, with a separation efficiency reaching up to 87%. This catalyst exhibits excellent photocatalytic performance and good stability.

[0065] The above description is merely a preferred embodiment of the present invention, but the invention is not limited to the disclosed content. Therefore, any modifications or equivalents made without departing from the scope of the present invention fall within the protection scope of the present invention.

Claims

1. A thiophene-based covalent triazine framework material exhibiting a cascade effect, characterized in that, The covalent triazine framework material includes 1509 cm -1 -1360 cm -1 There is an infrared absorption peak at the C=N bond of the triazine ring; in the solid-state 13C-CPNMR spectrum, a relatively broad signal is shown in the range of 180 to 160 ppm, which is attributed to the sp² carbon atom in the triazine unit that connects the thiophene or phenyl unit.

2. The thiophene-based covalent triazine framework material with cascade effect according to claim 1, characterized in that, The material uses thiophene-based cyano compounds as a single building block precursor, and forms a covalent organic framework structure with triazine rings through a cyano trimerization reaction. The thiophene unit is benzothiophene or alkyl / aryl substituted thiophene.

3. The method for preparing the thiophene-based covalent triazine framework material with cascade effect according to claim 1 or 2, characterized in that, Includes the following steps: A cyano compound was mixed with an acid catalyst and heated under an inert atmosphere and a closed environment to carry out a trimerization reaction. After post-treatment, a yellow-brown thiophene-based covalent triazine framework material was obtained.

4. The preparation method according to claim 3, characterized in that, Cyano compounds include benzo[b]thiophene-2,5-dicyano, 5-(4-cyanophenyl)thiophene-2-carboxynitrile, and 2,5-dicyanothiophene.

5. The preparation method according to claim 3, characterized in that, The catalyst acid includes any one of zinc chloride, aluminum chloride, trifluoromethanesulfonic acid, trimethylsilyl trifluoromethanesulfonate, titanium tetrachloride, or methanesulfonic acid; The solid-liquid ratio of the cyano compound to the acid catalyst is 50-100:1-2 (mg:1mL).

6. The preparation method according to claim 3, characterized in that, The PhTh-CTF is heated to a specified reaction temperature of 80-150℃ and maintained for 1-5 days, preferably at 100℃ for 3 days.

7. A catalyst for the photocatalytic preparation of benzimidazole and its derivatives, characterized in that, The catalyst is the thiophene-based covalent triazine framework material with cascade effect as described in claim 1 or 2, or the thiophene-based covalent triazine framework material with cascade effect prepared by the preparation method described in any one of claims 3-6.

8. A method for preparing benzimidazole and its derivatives using the photocatalyst described in claim 7, characterized in that, Includes the following steps: At a certain temperature, o-phenylenediamine substrates and benzaldehyde substrates are added to a certain amount of organic solvent in a certain proportion, and then a certain amount of the photocatalyst described in claim 7 is added. Under light irradiation and an oxygen-containing atmosphere is introduced, the product of organic conversion is obtained after a period of time. The reaction formula is as follows: R1 is any one of alkyl, alkoxy, or halogen; R2 is any one of alkyl, alkoxy, or halogen; The alkyl group is C1-C 10 The alkoxy group is a straight-chain alkane or a branched-chain alkane; the alkoxy group includes one of methoxy, ethoxy, or propoxy; and the halogen is any one of F, Cl, Br, or I.

9. The method according to claim 8, characterized in that, The molar ratio of the o-phenylenediamine substrate to the benzaldehyde substrate is 1:1; the amount of catalyst used is 1% to 15% of the total mass of the o-phenylenediamine substrate and the benzaldehyde substrate; the organic solvent includes any one of dimethyl sulfoxide, acetone, acetonitrile, dichloromethane, methanol, ethanol, and N,N-dimethylformamide.

10. The method according to claim 8, characterized in that, The oxygen-containing atmosphere is air or pure oxygen, preferably pure oxygen; The visible light is emitted by ultraviolet LEDs, blue LEDs, white LEDs, green LEDs, or orange LEDs, preferably blue light emitted by blue LEDs; the stirring reaction at room temperature takes 6 to 24 hours, preferably 12 hours.

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