Aromatic biguanide-based covalent organic framework material and preparation method and application thereof

Abstract

The application relates to the technical field of photocatalytic materials, and discloses an aromatic biguanide-based covalent organic framework material, which is obtained through C-N coupling reaction of an organic framework material containing halogen atoms and an aromatic biguanide compound; wherein the molar ratio of the organic framework material containing halogen atoms to the aromatic biguanide compound is 1:7.5-15. The aromatic biguanide-based covalent organic framework material is constructed through side chain engineering, can efficiently catalyze drug micro-pollutants in water under visible light irradiation, realizes in-situ photocatalytic self-cleaning at the same time, the degradation products can effectively separate from the pores and the surface of the aromatic biguanide-based covalent organic framework material, active sites are released, and steps such as organic solvent elution are avoided, so that the application has certain reference function for the design and development of efficient green photocatalysts.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to an aromatic biguanide covalent organic framework material, its preparation method, and its application. Background Technology

[0002] In recent years, the negative impacts of emerging drug micropollutant exposure on the ecological environment and human health have attracted widespread attention. Drug pollution, represented by receptor blockers such as propranolol, antibiotics such as sulfamethoxazole, antihistamines such as loratadine, and antidepressants such as amitriptyline, is frequent worldwide. Therefore, reducing the environmental impact of micropollutants is a pressing global issue that needs to be addressed. Compared with technologies such as adsorption, membrane separation, biodegradation, and electrochemistry, photocatalysis has advantages such as directly utilizing solar energy, completely removing pollutants, and reducing secondary pollution. It has enormous potential in environmental remediation. Developing efficient and green catalysts combined with natural solar energy to degrade and mineralize pollutants in water bodies is one of the ideal approaches to solving water pollution.

[0003] Biguanides, as nitrogen-rich organic strong bases, exhibit a protonated state over a wide pH range. Their electron-rich conjugated structure also demonstrates excellent performance in catalyzing organic reactions. However, due to their high polarity, separation and purification are challenging in practical applications. Therefore, providing a photocatalytic material containing aromatic biguanide compounds that is easy to separate and recover for efficient catalytic degradation of drug micro-pollutants is a problem urgently needing to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides an aromatic biguanide covalent organic framework material (Aryl-BIG-COF), in which aromatic biguanide compounds are embedded in the covalent organic framework material to prepare a heterogeneous catalyst. This catalyst is easy to recover and can give full play to the application potential of aromatic biguanide compounds in water. It can efficiently catalyze the degradation of drug micropollutants in water under visible light irradiation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] On the one hand, the present invention provides an aromatic biguanide covalent organic framework material, which is obtained by CN coupling reaction between an organic framework material containing halogen atoms and an aromatic biguanide compound;

[0007] The molar ratio of the organic framework material containing halogen atoms to the aromatic biguanide compound is 1:7.5-15.

[0008] Preferably, the organic framework material containing halogen atoms is prepared by a solvothermal method using a monomer containing halogen atoms and an amino monomer.

[0009] Preferably, the halogen atom includes one or more of bromine, chlorine, and fluorine atoms.

[0010] Preferably, the aromatic biguanide compound includes one or more of metformin, phenformin, and 1,6-di-(N5-substituted phenyl-N1-diguanidine)hexane hydrochloride.

[0011] On the other hand, the present invention also provides a method for preparing the aromatic biguanide covalent organic framework material according to any one of the above claims, comprising the following steps:

[0012] (1) An organic framework material containing halogen atoms, an aromatic biguanide compound, a synthetic solvent and a catalyst are mixed and reacted to obtain an intermediate product;

[0013] (2) The intermediate product is dried to obtain an aromatic biguanide covalent organic framework material.

[0014] Preferably, the ratio of the total mass of the halogen-containing organic framework material and the aromatic biguanide compound to the mass of the synthetic solvent is 1:40-60.

[0015] Preferably, the synthesis solvent includes one or more of dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0016] Preferably, the catalyst comprises CuI and K2CO3.

[0017] Preferably, the molar ratio of the organic framework material containing halogen atoms to CuI is 1:1-2.

[0018] Preferably, the molar ratio of the organic framework material containing halogen atoms to K2CO3 is 1:20-30.

[0019] Preferably, the reaction temperature in step (1) is 100-130℃ and the reaction time is 36-48h.

[0020] Preferably, the drying is freeze drying, and the freeze drying temperature is -40°C for 12-24 hours.

[0021] Preferably, the process before drying further includes washing the intermediate product.

[0022] Preferably, the solvent used for washing is at least one of tetrahydrofuran and acetone.

[0023] Furthermore, the present invention also provides the application of the aromatic biguanide covalent organic framework material described in any one of the above claims or the aromatic biguanide covalent organic framework material prepared by any one of the above claims in the photocatalytic degradation of drug micropollutants.

[0024] This invention provides an aromatic biguanide covalent organic framework material, which has the following advantages compared with the prior art:

[0025] This invention employs side-chain engineering to construct a covalent organic framework material rich in aromatic biguanide groups. Under visible light irradiation, it can efficiently catalyze drug micro-pollutants in water, while simultaneously achieving in-situ photocatalytic self-cleaning. The degradation products can effectively detach from the pores and surface of the aromatic biguanide covalent organic framework material, releasing active sites and avoiding steps such as organic solvent elution. This invention provides a certain reference for the design and development of efficient green photocatalysts. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 Here is a SEM image of the Br-COF prepared in Example 1;

[0028] Figure 2 Here is a SEM image of Aryl-BIG-COF prepared in Example 1;

[0029] Figure 3 These are the FTIR spectra of Br-COF and Aryl-BIG-COF prepared in Example 1;

[0030] Figure 4 This is a schematic diagram of the photocatalytic degradation of propranolol using Br-COF and Aryl-BIG-COF in Application Example 1;

[0031] Figure 5 This is a schematic diagram of the cycle of Aryl-BIG-COF photocatalytic degradation of propranolol in Application Example 1;

[0032] Figure 6 These are the XRD patterns of Br-COF and Aryl-BIG-COF prepared in Example 1;

[0033] Figure 7 This is the XPS image of Aryl-BIG-COF prepared in Example 1. Detailed Implementation

[0034] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0035] In one aspect of the present invention, an aromatic biguanide covalent organic framework material is proposed, which is obtained by CN coupling reaction of an organic framework material containing halogen atoms and an aromatic biguanide compound under a cuprous iodide catalyst.

[0036] During the research, it was found that the orientation of guanidine compounds is difficult to control. If they are directly used as monomers for reaction, the specific surface area and crystallinity of COFs will be insufficient. This side chain engineering can introduce functional groups while maintaining the high crystallinity and high specific surface area of ​​the original COF.

[0037] In this invention, the molar ratio of the halogen-containing organic framework material to the aromatic biguanide compound is 1:7.5-15, for example, 1:7.5, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, etc. By limiting the ratio of the halogen-containing organic framework material to the aromatic biguanide compound, the functional group abundance and morphology / pore size of the aromatic biguanide-based covalent organic framework material can be controlled. Specifically, this ratio is directly proportional to the functional group abundance and inversely proportional to the pore size.

[0038] In this invention, the organic framework material containing halogen atoms is prepared by a solvothermal method from a monomer containing halogen atoms and an amino monomer; the halogen atoms include one or more of bromine atoms, chlorine atoms, and fluorine atoms.

[0039] In some embodiments of the present invention, the halogen-containing organic framework material is a bromine-containing organic framework material (Br-COF), and the preparation process using a solvothermal method is as follows: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde are condensed via a Schiff base reaction to obtain Br-COF. The molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde is 7:8.6, the reaction temperature is 100-150℃, and the reaction time is 72-96 h.

[0040] The aromatic biguanide compounds include one or more of metformin, phenethyl biguanide, and 1,6-di-(N5-substituted phenyl-N1-diguanide)hexane hydrochloride, such as 1,4-phenylbiguanide, phenylbiguanide, phenethyl biguanide, etc.

[0041] In another aspect, the present invention provides a method for preparing an aromatic biguanide covalent organic framework material, comprising the following steps:

[0042] Step S100. The organic framework material containing halogen atoms, aromatic biguanide compounds, synthesis solvent and catalyst are mixed and reacted to obtain an intermediate product.

[0043] In this step, the selection of organic framework materials containing halogen atoms, aromatic biguanide compounds, and synthetic solvents, as well as the relationship between their addition amounts, have been explained in detail above and will not be repeated here.

[0044] In this invention, the ratio of the total mass of the halogen-containing organic framework material and the aromatic biguanide compound to the mass of the synthetic solvent is 1:40-60, for example, 1:40, 1:45, 1:50, 1:55, 1:60, etc. By limiting the ratio of the synthetic solvent to the raw materials,

[0045] In this invention, the synthetic solvent includes one or more of dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone, preferably dimethyl sulfoxide. Adding a synthetic solvent can make the reaction more complete and improve the yield of aromatic biguanide covalent organic framework materials.

[0046] In this invention, the catalyst comprises CuI and K₂CO₃; the molar ratio of the halogen-containing organic framework material to CuI is 1:1-2, for example, 1:1, 1:1.5, 1:2, etc.; the molar ratio of the halogen-containing organic framework material to K₂CO₃ is 1:20-30, for example, 1:20, 1:25, 1:30, etc. Potassium carbonate is used as an acid-binding agent, and cuprous iodide as a catalyst. Excessive addition of potassium carbonate can lead to structural damage to the halogen-containing organic framework material.

[0047] In this invention, the reaction is a reflux reaction, and the reaction temperature is 100-130℃, for example, 100℃, 110℃, 120℃, 130℃, etc.; the reaction time is 36-48h, for example, 36h, 38h, 40h, 42h, 44h, 46h, 48h, etc. By heating and refluxing, a full CN coupling reaction can be promoted between the organic framework material containing halogen atoms and the aromatic biguanide compound.

[0048] In some embodiments of the present invention, the aromatic biguanide compound is 1,4-phenylenediguanidine, which is prepared as follows: phenylenediamine and dicyandiamine are heated under reflux in hydrochloric acid solution. After the reaction is complete, the mixture is rotary evaporated, ground and filtered with hot ethanol to obtain a light purple powder, 1,4-phenylenediguanidine. The molar ratio of phenylenediamine to dicyandiamine is 1:2, the concentration of hydrochloric acid solution is 1-3 mol / L, the molar ratio of the sum of the amounts of phenylenediamine and dicyandiamine added to the amount of hydrochloric acid added is 1:6-8, the reflux temperature is 100°C, and the time is 3 hours.

[0049] It should be noted that the specific embodiments described above are merely examples of organic framework materials containing halogen atoms and aromatic biguanide compounds, and do not therefore limit the organic framework materials containing halogen atoms and aromatic biguanide compounds in this invention to Br-COF and 1,4-phenylbisguanide, respectively. Furthermore, organic framework materials containing halogen atoms and aromatic biguanide compounds can be prepared by conventional methods or purchased commercially.

[0050] Step S200. The intermediate product is cooled, filtered under reduced pressure, washed, and dried to obtain an aromatic biguanide covalent organic framework material.

[0051] In this step, the cooling is natural cooling to room temperature, the decompression is vacuum filtration, and the filtration is solid-liquid separation. No specific limitation is made on the specific filtration method.

[0052] In this invention, the washing process involves using one or more of tetrahydrofuran, acetone, water, and ethanol, and the washing is performed 2-8 times, preferably 4-8 times, for example, 4, 5, 6, 7, or 8 times. Washing removes impurities from the precipitate obtained after solid-liquid separation, improving the purity of the product.

[0053] In this invention, the drying process is freeze-drying, with a temperature of -40°C and a duration of 12-24 hours, such as 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, or 24 hours. It should be noted that slight fluctuations in vacuum level and freeze-drying temperature during this process will not significantly affect the drying effect and can be adjusted appropriately according to standard operating procedures.

[0054] Furthermore, the present invention also provides the application of the aromatic biguanide covalent organic framework material described in any one of the above claims or the aromatic biguanide covalent organic framework material prepared by any one of the above claims in the photocatalytic degradation of drug micropollutants, wherein the drug micropollutants may be one or more of propranolol, bisphenol A, norfloxacin, tetracycline, etc.

[0055] The technical solution of the present invention will now be described in detail through specific embodiments.

[0056] Example 1

[0057] (1) Br-COF was synthesized by Schiff base condensation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde using a hot solvent method; wherein the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde was 7:8.6, the reaction temperature was 120℃, and the reaction time was 72h;

[0058] (2) Phenylenediamine and dicyandiamine were heated in 50 mL of 1 mol / L HCl at a molar ratio of 1:2 and refluxed at 100 °C for 3 h. After the reaction was completed, the mixture was evaporated under reduced pressure until it was oily. Then, hot ethanol was added and the mixture was quickly ground until crystals precipitated. The mixture was filtered while hot, washed twice with ethanol, and then recrystallized with water-acetone to obtain a light purple powder, 1,4-phenylenediguanidine.

[0059] (3) Br-COF and 1,4-benzylbisguanidine were mixed at a molar ratio of 1:8 and added to 50 ml of dimethyl sulfoxide solvent. CuI and K2CO3 were then added. The mixture was refluxed at 110 °C for 48 h under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature and filtered under reduced pressure. The precipitate was washed three times with water and ethanol, respectively, and then freeze-dried at -40 °C for 12 h to obtain Aryl-BIG-COF. The molar ratio of Br-COF to CuI was 1:1.5, and the molar ratio of Br-COF to K2CO3 was 1:25.

[0060] like Figure 1 , 2 Figures 3 and 4 show SEM images of Br-COF, Aryl-BIG-COF, and FTIR images of Br-COF and Aryl-BIG-COF prepared in this embodiment, respectively.

[0061] Depend on Figure 1 and Figure 2 Comparison shows that the SEM image of Aryl-BIG-COF obtained after introducing aromatic biguanide groups changes from the original fibrous structure to a coral-like structure with more compact pores compared to Br-COF. Figure 3 1590 cm⁻¹ in the FTIR spectrum of Br-COF -1 and 613cm- 1 The peaks are the stretching vibration peak of C=N formed by the condensation of the aldehyde group of 2,5-dibromophenyl-1,4-dicarboxaldehyde and the amino group of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and the bending vibration peak of C-Br, respectively. In the Aryl-BIG-COF infrared spectrum, the bending vibration peak of C-Br disappears, and a peak appears at 3315 cm⁻¹. -1 3185cm -1 and 1385cm-1 The characteristic peaks of stretching vibrations of -NH2, -NH-, and -CN- in the biguanide structure prove that 1,4-benzylbisguanide successfully reacts with -Br in Br-COF and enters the COF framework as a side chain.

[0062] Example 2

[0063] (1) Br-COF was synthesized by Schiff base condensation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde using a hot solvent method, wherein the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde was 7:8.6, the reaction temperature was 150℃, and the reaction time was 96h.

[0064] (2) Phenylenediamine and dicyandiamine were heated in 50 mL of 2 mol / L HCl at a molar ratio of 1:2 and refluxed at 100 °C for 3 h. After the reaction was completed, the mixture was evaporated under reduced pressure until it was oily. Then, hot ethanol was added and the mixture was quickly ground until crystals precipitated. The mixture was filtered while hot, washed twice with ethanol, and then recrystallized with water-acetone to obtain a light purple powder, 1,4-phenylenediguanidine.

[0065] (3) Br-COF and 1,4-benzylbisguanidine were mixed at a molar ratio of 1:10 and added to 50 ml of dimethyl sulfoxide solvent. CuI and K2CO3 were then added. Under nitrogen protection, the mixture was refluxed at 110 °C for 48 h. After the reaction was completed, the mixture was cooled to room temperature and filtered under reduced pressure. The precipitate was washed three times with water and ethanol, respectively, and then freeze-dried at -40 °C for 12 h to obtain Aryl-BIG-COF. The molar ratio of Br-COF to CuI was 1:1.5, and the molar ratio of Br-COF to K2CO3 was 1:25.

[0066] Example 3

[0067] (1) Br-COF was synthesized by Schiff base condensation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde using a hot solvent method, wherein the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dibromo-terephthalaldehyde was 7:8.6, the reaction temperature was 150℃, and the reaction time was 96h.

[0068] (2) Phenylenediamine and dicyandiamine were heated in 50 mL of 2 mol / L HCl at a molar ratio of 1:2 and refluxed at 100 °C for 3 h. After the reaction was completed, the mixture was evaporated under reduced pressure until it was oily. Then, hot ethanol was added and the mixture was quickly ground until crystals precipitated. The mixture was filtered while hot, washed twice with ethanol, and then recrystallized with water-acetone to obtain a light purple powder, 1,4-phenylenediguanidine.

[0069] (3) Br-COF and 1,4-benzylbisguanidine were mixed at a molar ratio of 1:15 and added to 50 ml of dimethyl sulfoxide solvent. CuI and K2CO3 were then added. Under nitrogen protection, the mixture was refluxed at 110 °C for 36 h. After the reaction was completed, the mixture was cooled to room temperature and filtered under reduced pressure. The precipitate was washed three times with water and ethanol, respectively, and then freeze-dried at -40 °C for 24 h to obtain Aryl-BIG-COF. The molar ratio of Br-COF to CuI was 1:2 and the molar ratio of Br-COF to K2CO3 was 1:25.

[0070] Example 4

[0071] Example 4 is basically the same as Example 1, except that Br-COF is replaced with Cl-COF. The preparation method of Cl-COF is as follows:

[0072] Cl-COF was synthesized by Schiff base condensation of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dichloroterephthalaldehyde using a hot solvent method; wherein the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dichloroterephthalaldehyde was 7:8.6, the reaction temperature was 120℃, and the reaction time was 72 h.

[0073] Example 5

[0074] Example 5 is basically the same as Example 1, except that 1,4-benzidine is replaced with phenethylbiguanide (commercially available).

[0075] Application Example 1

[0076] Photocatalytic experiment: Br-COF and Aryl-BIG-COF prepared in Example 1 were added to a constant-temperature reaction system with a propranolol concentration of 20 ppm. The experimental system was first stirred in the dark for 30 min, and samples were taken every 5 min. After reaching adsorption-desorption equilibrium, a 300W xenon lamp was used as the light source with an incident wavelength of 420-780 nm. Samples were taken every 5 min, filtered, and detected by high performance liquid chromatography. The concentration change of propranolol during adsorption and catalysis was determined based on the standard curve established by a series of standard solutions.

[0077] like Figure 4The figure shows a schematic diagram of the visible light catalytic degradation of propranolol by Br-COF and Aryl-BIG-COF prepared in Example 1. As can be seen from the figure, under the action of Aryl-BIG-COF, propranolol was completely removed after 40 min of light catalysis. Compared with Br-COF, the adsorption and catalytic performance were significantly enhanced. This indicates that the intercalation of the aromatic biguanide group not only achieves effective adsorption and capture of propranolol molecules, but also achieves effective absorption of visible light through electronic structure regulation, thereby improving the efficient catalytic degradation effect. This allows pollutant molecules to be removed efficiently.

[0078] After the photocatalytic reaction of Aryl-BIG-COF was completed (with each cycle lasting 1 hour), a high concentration of pollutant was added directly to the reaction system before each cycle. The concentration of the pollutant substrate was adjusted to the initial concentration (20 ppm) before starting the next round of experiments, with the experimental conditions remaining the same.

[0079] like Figure 5 The figure shows the removal rate of propranolol by Aryl-BIG-COF prepared in Example 1 after 6 in-situ cycles under visible light. The results show that the overall removal rate of propranolol can still reach 90.4% after 6 cycles. This indicates that Aryl-BIG-COF can achieve in-situ self-cleaning under visible light, and the degradation products can effectively detach from the pores and surface of Aryl-BIG-COF, releasing active sites. The reduced interlayer spacing and pore size of the prepared Aryl-BIG-COF due to the introduction of aromatic biguanide groups are conducive to the release of degradation products and avoid steps such as organic solvent elution, providing some reference for the design concept of green COF catalysts.

[0080] Application Example 2

[0081] In this invention, photocatalytic experiments were conducted on tetracycline, bisphenol A, and norfloxacin, all with an initial concentration of 20 ppm, under the same experimental conditions as in Application Example 1.

[0082] Experimental results show that Aryl-BIG-COF removes 97.70% of tetracycline within 60 min, 97.36% of bisphenol A within 120 min, and 91.79% of norfloxacin within 150 min.

[0083] In summary, this invention utilizes aromatic biguanide groups as functional side chains embedded in a COF matrix to prepare a heterogeneous catalyst. Characterization techniques such as XRD, FT-IR, and XPS confirmed the successful introduction of the aromatic biguanide side chains while maintaining the high crystallinity of the original COF. The prepared photocatalytic material can efficiently remove drug micropollutants from water under visible light through targeted trapping and enhanced catalysis, achieving a concentration of 0.20 g·L⁻¹. -1At the same dosage, compared with Br-COF, the adsorption capacity of Aryl-BIG-COF for propranolol increased from 6.89 mg / g to 31.68 mg / g, and the pseudo-first-order rate constant of photocatalytic degradation increased from 0.013 min. -1 It was improved to 0.089 min. -1 After six cycles of in-situ regeneration, the removal rate of drug micro-pollutants can still reach over 90%. This means that while the active groups introduced through side-chain engineering enhance the material's targeted capture of pollutant molecules, the conjugated structure can also effectively regulate the electronic band structure of COFs by controlling electron transport, thereby improving the electron-hole separation efficiency and achieving dual-function enhanced high-efficiency pollutant removal from COFs.

[0084] The embodiments of the present invention have been shown and described above. It is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An aromatic biguanide covalent organic framework material, characterized in that, It is obtained by CN coupling reaction between organic framework materials containing halogen atoms and aromatic biguanide compounds; The molar ratio of the halogen-containing organic framework material to the aromatic biguanide compound is 1:7.5-15. The halogen-containing organic framework material is prepared by a solvothermal method using a halogen-containing monomer and an amino monomer, wherein the halogen-containing monomer is 2,5-dibromo-terephthalaldehyde or 2,5-dichloro-terephthalaldehyde, and the amino monomer is 2,4,6-tris(4-aminophenyl)-1,3,5-triazine.

2. The aromatic biguanide covalent organic framework material according to claim 1, characterized in that, The aromatic biguanide compounds include one or more of 1,4-benzylbiguanide, phenylbiguanide, phenethylbiguanide, and 1,6-di-(N5-substituted phenyl-N1-diguanide)hexane hydrochloride.

3. A method for preparing the aromatic biguanide covalent organic framework material according to claim 1 or 2, characterized in that, Includes the following steps: (1) An organic framework material containing halogen atoms, an aromatic biguanide compound, a synthetic solvent and a catalyst are mixed and reacted to obtain an intermediate product; (2) The intermediate product is dried to obtain an aromatic biguanide covalent organic framework material.

4. The method for preparing the aromatic biguanide covalent organic framework material according to claim 3, characterized in that, The ratio of the total mass of the halogen-containing organic framework material and the aromatic biguanide compound to the mass of the synthetic solvent is 1:40-60; The synthesis solvent includes one or more of dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone.

5. The method for preparing the aromatic biguanide covalent organic framework material according to claim 3, characterized in that, The catalyst includes CuI and K2CO3; The molar ratio of the organic framework material containing halogen atoms to CuI is 1:1-2, and the molar ratio of the organic framework material containing halogen atoms to K2CO3 is 1:20-30.

6. The method for preparing the aromatic biguanide covalent organic framework material according to claim 3, characterized in that, The reaction temperature in step (1) is 100-130℃ and the reaction time is 36-48h.

7. The method for preparing the aromatic biguanide covalent organic framework material according to claim 3, characterized in that, The drying process is freeze drying, and the freeze drying temperature is -40℃ for 12-24 hours.

8. The method for preparing the aromatic biguanide covalent organic framework material according to any one of claims 3-7, characterized in that, The process before drying also includes washing the intermediate product; The solvent used for washing is at least one of tetrahydrofuran, acetone, water, and ethanol.

9. The application of an aromatic biguanide covalent organic framework material according to claim 1 or 2, or an aromatic biguanide covalent organic framework material prepared by any one of claims 3-8, in the photocatalytic degradation of drug micropollutants.

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