Preparation and application of benzoselenadiazole covalent organic framework material

Abstract

The invention belongs to the technical field of organic photoelectric materials, and particularly relates to preparation and application of a benzoselenadiazole covalent organic framework material. According to the invention, benzoselenadiazolyl tetraaldehyde is used as a construction unit, o-toluidine, 4, 4 '-biphenyl diamine or 3, 3'-dihydroxybenzidine is used as a connecting body, and three kinds of novel rigid COFs, namely HBU-COF-CH3, HBU-COF-H and HBU-COF-OH, are synthesized in sequence. The COFs has high cycling stability, has outstanding advantages in the aspect of sustainable heterogeneity of molecular catalysts, and can be used as a heterogeneous photocatalyst to realize efficient hydrogen peroxide production under visible light, and the photocatalytic hydrogen peroxide production performance of the COFs is superior to that of most reported COFs materials. Wherein the yields of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH are as high as 12910 [mu] mol g <-1 > h <-1 >, 8838 [mu] mol g <-1 > h <-1 > and 7679 [mu] mol g <-1 > h <-1 > in sequence.

Description

Technical Field

[0001] The invention belongs to the technical field of organic photoelectric materials, and specifically relates to the preparation and application of benzoselenadiazole-based covalent organic framework materials. Background Art

[0002] Hydrogen peroxide is a very common basic chemical in life and an important green oxidizing / reducing agent. In the oxidation / reduction process, the only product is water, which will not cause environmental pollution. Thanks to this advantage, hydrogen peroxide is widely used in industries such as papermaking (bleaching agent), chemical industry (oxidizing / reducing agent), chemical oxygen production, food production (deoxidizer), agriculture (degradation of residual pesticides), medical treatment (disinfectant) and electronic device applications (cleaning agent and corrosive agent). In the past 200 years, hydrogen peroxide has received more and more attention and has become one of the 100 most important chemicals in the world.

[0003] To date, a variety of strategies have been developed to achieve the synthesis of hydrogen peroxide, including the isopropanol method, the direct hydroxyl method, and the anthraquinone method. However, these methods all have certain limitations. In the early 20th century, the anthraquinone method was used to produce hydrogen peroxide, and this process is still the most commonly used method for industrial production of hydrogen peroxide today. About 95% of hydrogen peroxide in the global market is prepared by this method. However, this method is prone to produce by-products such as octahydroanthraquinone that are difficult to be degraded by the environment during the production process, thereby polluting the environment. In addition, the palladium catalyst is expensive and the production process consumes a lot of energy, which does not meet the standards of a green economy.

[0004] Solar radiation is a clean and renewable energy source. Using unlimited solar energy to carry out photocatalytic reactions to prepare valuable chemicals has become a new means to replace the traditional production of hydrogen peroxide. This method has no product, and the raw materials are also readily available water and oxygen. Under natural light conditions, the designed photocatalyst can react to produce hydrogen peroxide. In recent years, emerging crystalline porous framework materials, such as covalent organic frameworks (COFs) materials, have become new functional platforms for photocatalysis. Compared with traditional inorganic semiconductors, they have unique advantages, such as coordinated structure, high specific surface area, and easy post-synthesis modification. Since COFs formed by covalent bonds have high stability in water, COFs materials with different structures and topologies have shown excellent photocatalytic performance. However, the yield of photocatalytic hydrogen peroxide production by most COFs materials is still low. Therefore, there is still a lot of room for improvement in the photocatalytic hydrogen peroxide production performance of COFs materials. Summary of the invention

[0005] In view of the problem that the existing COFs materials have insufficient photocatalytic hydrogen peroxide production capacity, the purpose of the present invention is to provide a method for preparing a benzoselenadiazole-based covalent organic framework (COFs) material, and use the obtained COFs material as a heterogeneous photocatalyst to catalyze the production of hydrogen peroxide.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A benzoselenadiazole-based covalent organic framework material, wherein the benzoselenadiazole-based covalent organic framework material is HBU-COF-CH3, HBU-COF-H or HBU-COF-OH, which uses benzoselenadiazole tetraaldehyde (BSeDP) as a building unit and o-tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine as a linker.

[0007] The method for preparing the above-mentioned benzoselenadiazole-based covalent organic framework material comprises the following steps: S1: Synthesis of BSeDP 4,7-dibromo-2,1,3-benzoselenadiazole is mixed with 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalaldehyde, potassium carbonate, tetrakis(triphenylphosphine)palladium, tetrahydrofuran and deionized water, and stirred at 70-95° C. for 24-36 hours under an inert atmosphere; the reaction mixture is cooled to room temperature and filtered; the filter residue is washed with deionized water, tetrahydrofuran and methanol respectively, and dried at room temperature to obtain BSeDP; S2: Synthesis of HBU-COF-CH3, HBU-COF-H or HBU-COF-OH o-Tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine are respectively mixed with BSeDP, o-dichlorobenzene, n-butanol and acetic acid aqueous solution in a Pyrex tube, and after ultrasonic treatment for 15 minutes, they are quickly frozen in a liquid nitrogen bath; the frozen Pyrex tube is degassed and slowly thawed to room temperature; after repeating the above process 3 times, the Pyrex tube is sealed and reacted at 120°C for 3 days to obtain a yellow precipitate; after filtering, washing and vacuum drying in sequence, the target benzoselenadiazole-based covalent organic framework material HBU-COF-CH3, HBU-COF-H or HBU-COF-OH is obtained.

[0008] Further, in step S1, the ratio of each component is: 1 equivalent of 4,7-dibromo-2,1,3-benzoselenadiazole; 2.2 equivalents of 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalaldehyde; 4 equivalents of potassium carbonate; 0.05 equivalent of tetrakis(triphenylphosphine)palladium; v:v=5:1 tetrahydrofuran and deionized water; In step S2, the ratio of each component is: 2 equivalents of o-tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine; 1 equivalent of BSeDP; the volume ratio of o-dichlorobenzene: n-butanol: acetic acid aqueous solution is 05:0.5:0.1.

[0009] The present invention also provides the use of the above-mentioned benzoselenadiazole-based covalent organic framework material in heterogeneous photocatalytic production of hydrogen peroxide.

[0010] The present invention also provides a heterogeneous photocatalyst, which is prepared using the above-mentioned benzoselenadiazole-based covalent organic framework material as a raw material.

[0011] Furthermore, the above-mentioned heterogeneous photocatalyst is used to catalyze the production of hydrogen peroxide.

[0012] The present invention uses benzoselenadiazole tetraaldehyde as a building block and o-tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine as a linker to sequentially synthesize three new rigid COFs: HBU-COF-CH3, HBU-COF-H and HBU-COF-OH. The COFs have high cyclic stability and outstanding advantages in the sustainable heterogeneity of molecular catalysts. They can be used as heterogeneous photocatalysts to achieve efficient production of hydrogen peroxide under visible light, and their photocatalytic hydrogen peroxide production performance is better than most reported COFs materials. Among them, the yields of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH are as high as 12910μmol g -1 h -1 , 8838 μmol g -1 h -1 、7679μmol g -1 h -1 .

[0013] In addition, the differences in the photocatalytic hydrogen peroxide production performance of the three COFs materials of the present invention may be caused by the synergistic effect between the different substituent modifications and pore properties of the materials. Therefore, the present invention will provide a useful idea for designing high-performance covalent organic framework photocatalysts for photosynthesis of hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the synthesis of BSeDP.

[0015] Figure 2 Schematic diagram of the synthesis of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH.

[0016] Figure 3Powder diffraction spectra of HBU-COF-CH3 (a), HBU-COF-H (b), and HBU-COF-OH (c) and their attributions.

[0017] Figure 4 N2 adsorption (hollow) and desorption (solid) curves of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH at 77 K.

[0018] Figure 5 Infrared spectra of HBU-COF-CH3 (a), HBU-COF-H (b), HBU-COF-OH (c) and their building block references: BSeDP, o-tolidine, 4,4'-diphenylenediamine, and 3,3'-dihydroxybenzidine.

[0019] Figure 6 Infrared spectra of HBU-COF-CH3 (a), HBU-COF-H (b), and HBU-COF-OH (c) after being immersed in different solvents for two days.

[0020] Figure 7 These are the test results of the photocatalytic hydrogen peroxide production performance of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH.

[0021] Figure 8 The photocatalytic cycle rate diagram of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH.

[0022] Fig. 9 This is a comparison chart of the photocatalytic hydrogen peroxide production rate of HBU-COF-CH3 under different conditions. DETAILED DESCRIPTION

[0023] Example 1 Synthesis of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH S1: Synthesis of BSeDP The synthesis diagram of BSeDP is shown in Figure 1 shown.

[0024] A mixture of 4,7-dibromo-2,1,3-benzoselenadiazole (340.9 mg, 1.0 mmol), 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalaldehyde (572.0 mg, 2.2 mmol), potassium carbonate (552.8 mg, 4 mmol), tetrakis(triphenylphosphine)palladium (57.8 mg, 0.05 mmol), tetrahydrofuran (10.0 mL) and deionized water (2.0 mL) was placed in a 50 mL flask; stirred at 90 °C for 30.0 hours under nitrogen. The reaction mixture was cooled to room temperature and filtered. The filter residue was washed with 15.0 mL deionized water, 15.0 mL tetrahydrofuran and 15.0 mL methanol, respectively, and finally dried at room temperature to obtain 336.1 mg BSeDP.

[0025] S2: Synthesis of HBU-COF-CH 3、 HBU-COF-H and HBU-COF-OH HBU-COF-CH 3、 The synthesis diagram of HBU-COF-H and HBU-COF-OH is shown in Figure 2 shown.

[0026] S2-1: Synthesis of HBU-COF-CH3 Into a 9×6 mm, od×id Pyrex tube were added 13.4 mg, 0.03 mmol of BSeDP, 14.6 mg, 0.06 mmol of o-tolidine, 0.5 mL of o-dichlorobenzene, 0.5 mL of n-butanol, and 0.1 mL of 6 M aqueous acetic acid; the Pyrex tube was sonicated for 15 min, and then after rapid freezing in a liquid nitrogen bath, the frozen Pyrex tube was degassed and slowly thawed to room temperature; after the process was repeated 3 times, the Pyrex tube was sealed; the reaction was carried out at 120°C for 3 days to produce a yellow precipitate; the solid was separated by filtration and washed 3 times with o-dichlorobenzene and acetone in sequence; the product was collected and dried in vacuo at 100°C to obtain 18.2 mg of yellow powder HBU-COF-CH3 with a yield of 70.4%.

[0027] S2-2: Synthesis of HBU-COF-H Into a 9×6 mm, od×id Pyrex tube were added 13.4 mg, 0.03 mmol of BSeDP, 11.0 mg, 0.06 mmol of 4,4'-diphenylenediamine, 0.5 mL of o-dichlorobenzene, 0.5 mL of n-butanol, and 0.1 mL of 6M aqueous acetic acid solution; the Pyrex tube was sonicated for 15 min, and then after rapid freezing in a liquid nitrogen bath, the frozen Pyrex tube was degassed and slowly thawed to room temperature; after the process was repeated 3 times, the Pyrex tube was sealed; the reaction was carried out at 120°C for 3 days to produce a yellow precipitate; the solid was separated by filtration and washed 3 times with o-dichlorobenzene and acetone in sequence; the product was collected and dried in vacuo at 100°C to obtain 19.5 mg of yellow powder HBU-COF-H with a yield of 87.6%.

[0028] S2-3: Synthesis of HBU-COF-OH Into a 9×6 mm, od×id Pyrex tube were added 13.4 mg, 0.03 mmol of BSeDP, 13.0 mg, 0.06 mmol of 3,3'-dihydroxybenzidine, 0.5 mL of o-dichlorobenzene, 0.5 mL of n-butanol, and 0.1 mL of 6M aqueous acetic acid solution; the Pyrex tube was sonicated for 15 min, and then after rapid freezing in a liquid nitrogen bath, the frozen Pyrex tube was degassed and slowly thawed to room temperature; after the process was repeated 3 times, the Pyrex tube was sealed; the reaction was carried out at 120°C for 3 days to produce a yellow precipitate; the solid was separated by filtration and washed 3 times with o-dichlorobenzene and acetone in sequence; the product was collected and dried in vacuo at 100°C to obtain 18.7 mg of yellow powder HBU-COF-OH with a yield of 76.0%.

[0029] Example 2 Structural Characterization of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH (1) Powder X-ray diffraction (PXRD) data were collected at room temperature using a Rigaku Mini Flex600 diffractometer to determine the periodic structure of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH. Instrument parameters: A graphite monochromatized Cu target was used as the X-ray light source, the test voltage was 50KV, the test current was 40mA, and the test range was 2.5-40°. Powder X-ray diffraction (PXRD) analysis was used to study the periodicity of the structures of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH. Figure 3As shown in Figure 2, the strong peak at 4.08° and the relatively weak peaks at 7.90, 8.33, 16.24, and 24.64° in the PXRD pattern are assigned to the (110), (220), (130), (350), and (001) crystal planes, respectively. The space group was established using the Materials Studio software package. P 3 HBU-COF-CH3 and HBU-COF-OH and P The simulated PXRD patterns of HBU-COF-H and AA stacking structure models of 6 space groups are basically consistent with the experimental synthesis results.

[0030] The above results show that these three materials have good crystallinity. P 3 space groups of HBU-COF-CH3 and HBU-COF-OH and P The experimental PXRD patterns of HBU-COF-H with 6 space groups are consistent with the simulation data based on the formation of heteroporous COF structure. Their respective Pawley refinement parameters and stacking structure schematics are shown in Figure 2. Figure 3 a), b), and c).

[0031] (2) Micromeritics ASAP 2020 PLUS HD88 was used to measure the nitrogen adsorption and desorption isotherms of HBU-COF-CH3, HBU-COF-OH, and HBU-COF-H at 77 K. Before the measurement, the samples were degassed at 120° for 10.0 h. The BET areas were: 1124 m 2 / g, 569 m 2 / g and 479 m 2 / g( Figure 4 ). This indicates that the COFs material of the present invention has a permanent pore structure.

[0032] (3) The infrared spectra of HBU-COF-CH3, HBU-COF-H, HBU-COF-OH and the building block references: benzoselenadiazole tetraaldehyde, o-tolidine, 4,4'-diphenylenediamine, and 3,3'-dihydroxybenzidine were measured using a Thermo Fisher Nicolet iS10 spectrometer with a KBr pellet method at a resolution of 1 cm -1 The detection results of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH are as follows: Figure 5 a), b), and c).

[0033] (4) HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH were immersed in 6M aqueous hydrochloric acid and sodium hydroxide solutions and organic solvents such as N,N-dimethylformamide, tetrahydrofuran, and ethanol for 2 days, and then filtered and infrared spectra were measured. The infrared spectra of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH were as follows: Figure 6 a), b), and c). Figure 5 and Figure 6 The results show that the COFs material of the present invention has a permanent pore structure and a stable structure.

[0034] Example 3 Photocatalytic Applications of HBU-COF-CH3, HBU-COF-H and HBU-COF-OH (1) The specific scheme for photocatalytic production of hydrogen peroxide is: HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH were used as catalysts, respectively. The catalysts (2.5 mg) were dispersed in 25.0 mL of 5% ethanol aqueous solution and ultrasonically dispersed for 30 minutes. During the entire photocatalytic process, O2 was bubbled into the suspension, and then the concentration of H2O2 was measured by UV-visible spectrophotometer after different illumination times. For example, 1.0 mL of liquid was filtered with a 0.22 mm filter to remove the photocatalyst. The sample was mixed with a pre-prepared Ce(SO4)2 solution, and the concentration of H2O2 was measured by UV-visible spectrophotometer. The UV spectrophotometric Ce(SO4)2 colorimetric method follows the following reaction formula, in which the yellow Ce 4+ Reacts with H2O2 to generate colorless Ce 3+ .

[0035] ; The concentration of H2O2 produced by photocatalysis can be calculated by the following equation: .

[0036] Dissolve 16.6 mg Ce(SO4)2 in 50 mL 0.5 M sulfuric acid solution to prepare a yellow, transparent 1 mM Ce(SO4)2 solution. In order to obtain a standard curve, a UV / vis spectrometer was used to measure the UV-visible absorption spectra of Ce(SO4)2 solutions of different concentrations. 4+ The linear relationship between the concentration and the photocatalytic H2O2 can be used to obtain the concentration of H2O2 in the sample. From this, the yield of H2O2 produced by photocatalysis can be calculated. Figure 7 is the yield of photocatalytic hydrogen peroxide production of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH.

[0037] (2) In the cyclic stability test experiment, the photocatalysts HBU-COF-CH3, HBU-COF-H and HBU-COF-OH were subjected to cyclic experiments with continuous illumination for multiple times (25 minutes each time). Figure 8 The photocatalytic cycle rate diagram of HBU-COF-CH3, HBU-COF-H, and HBU-COF-OH is shown, indicating that the COFs material of the present invention has good recycling performance. Fig. 9 The results show the photocatalytic hydrogen peroxide production yield of HBU-COF-CH3 under different reaction conditions (normal conditions, no catalyst, no light, no oxygen, air conditions, and no sacrificial agent). The results show that oxygen, light, and catalysts are essential for the production of hydrogen peroxide. Compared with the 5% ethanol aqueous solution containing a sacrificial agent as the reaction solvent, the pure water reaction solution showed lower catalytic activity.

Claims

1. A benzoselenadiazole-based covalent organic framework material, characterized in that: The benzoselenadiazole-based covalent organic framework material is HBU-COF-CH3, HBU-COF-H or HBU-COF-OH, which uses benzoselenadiazole tetraaldehyde as a building unit and o-tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine as a linker.

2. The method for preparing the benzoselenadiazole-based covalent organic framework material according to claim 1, characterized in that: The following steps are involved: S1: Synthesis of BSeDP 4,7-dibromo-2,1,3-benzoselenadiazole is mixed with 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalaldehyde, potassium carbonate, tetrakis(triphenylphosphine)palladium, tetrahydrofuran and deionized water, and stirred at 70-95° C. for 24-36 hours under an inert atmosphere; the reaction mixture is cooled to room temperature and filtered; the filter residue is washed with deionized water, tetrahydrofuran and methanol respectively, and dried at room temperature to obtain BSeDP; S2: Synthesis of HBU-COF-CH3, HBU-COF-H or HBU-COF-OH o-Tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine are respectively mixed with BseDP, o-dichlorobenzene, n-butanol and acetic acid aqueous solution in a Pyrex tube, and after ultrasonic treatment for 15 minutes, they are quickly frozen in a liquid nitrogen bath; the frozen Pyrex tube is degassed and slowly thawed to room temperature; after repeating the above process 3 times, the Pyrex tube is sealed and reacted at 120°C for 3 days to obtain a yellow precipitate; after filtering, washing and vacuum drying in sequence, the target benzoselenadiazole-based covalent organic framework material HBU-COF-CH3, HBU-COF-H or HBU-COF-OH is obtained.

3. The preparation method according to claim 2, characterized in that: In step S1, the ratio of each component is: 1 equivalent of 4,7-dibromo-2,1,3-benzoselenadiazole; 2.2 equivalents of 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalaldehyde; 4 equivalents of potassium carbonate; 0.05 equivalent of tetrakis(triphenylphosphine)palladium; v:v=5:1 tetrahydrofuran and deionized water; In step S2, the ratio of each component is: 2 equivalents of o-tolidine, 4,4'-diphenylenediamine or 3,3'-dihydroxybenzidine; 1 equivalent of BseDP; the volume ratio of o-dichlorobenzene: n-butanol: acetic acid aqueous solution is 05:0.5:0.

1.

4. Use of the benzoselenadiazole-based covalent organic framework material according to claim 1 in heterogeneous photocatalytic production of hydrogen peroxide.

5. A heterogeneous photocatalyst, characterized in that: The benzoselenadiazole covalent organic framework material according to claim 1 is used as a raw material for preparation.

6. Use of the heterogeneous photocatalyst according to claim 5 in catalytic production of hydrogen peroxide.

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