A Cd-MOF material, its preparation method and application

Abstract

This invention relates to the field of photocatalysis, specifically to a Cd-MOF material, its preparation method, and its applications. The preparation method involves dissolving 2,6-naphthalenedicarboxylic acid, the organic ligand 2,5-bis(pyridin-4-yl)thiazo[5,4-d]thiazole, and cadmium nitrate tetrahydrate in N,N-dimethylformamide, stirring until homogeneous, sealing in a glass bottle, and carrying out a solvothermal reaction to obtain the Cd-MOF material. The Cd-MOF material can efficiently photocatalyze the degradation of dyes in water, exhibiting high catalytic activity as a catalyst. Furthermore, the prepared Cd-MOF is used as a catalyst for photocatalytic amine oxidative coupling to prepare imines. Using air as an oxygen source, the light utilization rate is high, the reaction conditions are mild, and a high yield of the product is obtained. The Cd-MOF photocatalyst has a short reaction time, high catalytic activity, good stability, and is recyclable.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, specifically to a Cd-MOF material, its preparation method, and its application. Background Technology

[0002] In recent years, the rapid development of science and technology and society has led to the large-scale exploitation of fossil fuels, resulting in energy shortages and environmental pollution. Developing alternative clean energy sources is therefore urgently needed. Compared to traditional thermocatalytic organic synthesis reactions, photocatalytic reactions are widely used in environmental remediation, energy conversion, and organic synthesis due to their simplicity and environmental friendliness. Imines, as important intermediates, have attracted widespread attention in the pharmaceutical and biological fields. Traditional imine synthesis typically requires unstable aldehydes as raw materials, Lewis acid catalysts, and dehydrating agents. Therefore, efforts are being made to develop green, efficient, and economical imine synthesis methods. Photocatalytic conversion of benzylamine directly to the corresponding imine provides a promising alternative for imine synthesis. Many heterogeneous catalysts have been developed for photocatalytic imine synthesis under mild conditions, but these photocatalysts still have many drawbacks, such as the need for oxygen introduction and high temperatures, which greatly hinder their practical application. Therefore, developing a highly efficient photocatalyst for a reaction system with air as the oxidant at room temperature remains a challenge. Metal-organic frameworks (MOFs), as organic-classical inorganic hybrid porous crystalline materials, possess large surface areas and are easily functionalized, making them an excellent platform for constructing photocatalysts. Therefore, developing MOF materials with mild operating conditions and improved light utilization efficiency has significant practical implications and promising application prospects for the photocatalytic preparation of imines.

[0003] Globally, numerous industries, including textiles, papermaking, food, and pharmaceuticals, release various toxic and harmful colored dyes into the environment during their production processes. These dyes, due to their low biodegradability, diverse colors, and high COD and BOD levels, cause serious harm to aquatic life. Photocatalytic degradation technology, with its environmentally friendly and highly efficient degradation advantages, has become a research hotspot in the field of environmental remediation. Among them, metal-organic frameworks (MOFs), organic-inorganic hybrid materials constructed from metal ions and organic ligands, are widely used in the photocatalytic degradation of organic dyes due to their high specific surface area, ideal topological structure, abundant surface active sites, and flexible modification capabilities. Summary of the Invention

[0004] This invention overcomes the shortcomings of existing technologies by providing a Cd-MOF material, its preparation method, and its applications. The invention employs a solvothermal method to prepare Cd-MOF materials, a simple operation. The Cd-MOF material can efficiently photocatalyze the degradation of dyes in water, exhibiting high catalytic activity as a catalyst. Furthermore, the prepared Cd-MOF is used as a catalyst for photocatalytic amine oxidative coupling to imines, using air as the oxygen source, resulting in high light utilization, mild reaction conditions, and high yields of the product. The Cd-MOF photocatalyst exhibits short reaction time, high catalytic activity, good stability, and is recyclable.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a Cd-MOF material with the molecular formula C 102 H 98 Cd3N 20 O 12 S6, whose crystal system belongs to the Monoclinic crystal system, has the following cell parameters: a=45.899(6) Å, b=17.4621(17) Å, c=33.535(4) Å, α=90°, β=132.477(5)°, γ=90°.

[0006] This invention provides a method for preparing Cd-MOF materials, wherein 2,6-naphthiacarboxylic acid, the organic ligand 2,5-bis(pyridin-4-yl)thiazo[5,4-d]thiazole, and cadmium nitrate tetrahydrate are dissolved in N,N-dimethylformamide, stirred evenly, sealed in a glass bottle, and subjected to a solvothermal reaction to obtain Cd-MOF materials.

[0007] As a further limitation of the technical solution of the present invention, the molar ratio of 2,6-naphthodicarboxylic acid, 2,5-bis(pyridin-4-yl)thiazo[5,4-d]thiazole and cadmium nitrate tetrahydrate is 1:1:2; the molar amount of 2,6-naphthodicarboxylic acid to the volume ratio of N,N-dimethylformamide is 3 mmol: 400 mL.

[0008] As a further limitation of the technical solution of the present invention, the temperature of the solvothermal reaction is 120°C and the time is 7 days.

[0009] In addition, the present invention also provides the application of the above-mentioned Cd-MOF material in the photocatalytic oxidative coupling of amines to prepare imines.

[0010] As a further limitation of the above technical solution, at room temperature, Cd-MOF material is used as a photocatalyst, and benzylamine and its derivatives are used as raw materials. An organic solvent is added, and an imine is obtained by catalytic reaction under simulated visible light irradiation and air atmosphere.

[0011] As a further limitation of the above technical solution, the raw material is benzylamine, 3-methylbenzylamine, 4-bromobenzylamine or 4-chlorobenzylamine; the organic solvent is anhydrous acetonitrile.

[0012] In addition, the invention also provides the application of the above-mentioned Cd-MOF material in the photocatalytic degradation of dyes in wastewater.

[0013] As a further refinement of the above technical solution, Cd-MOF is added as a catalyst to wastewater containing dyes. After the adsorption equilibrium is reached in the dark reaction, photocatalytic degradation is carried out under visible light irradiation.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention synthesizes Cd-MOF materials and provides a method for preparing imines by photocatalytic amine oxidative coupling using Cd-MOF materials. By screening the substrate concentration, reaction atmosphere, catalyst dosage, and solvent type, a series of imines with high yields (90%-99%) were obtained under optimized conditions. The method uses a small amount of catalyst, exhibits high catalytic activity, operates under mild reaction conditions, and allows for multiple catalyst recycling. Using air as the oxygen source results in low cost, low pollution, and environmental friendliness.

[0016] Furthermore, this invention also provides a method for photocatalytic degradation of dyes in wastewater using the Cd-MOF material synthesized in this invention. By screening the type of dye, catalyst capacity, reactant concentration, and pH of the aqueous solution, under optimized conditions, the degradation rate of Rhodamine B in water reached 99% after 30 minutes. Moreover, the catalyst used exhibits good stability and can be recycled multiple times. This method provides a new approach for constructing Cd-MOF catalysts to achieve photocatalytic degradation of dyes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the crystal structure of the Cd-MOF of the present invention.

[0018] Figure 2 This is a crystal molecular model diagram of the Cd-MOF of this invention.

[0019] Figure 3 The images are characterization plots of Cd-MOF, where a is the SEM plot, b is the XRD plot, c is the BET plot and D is the TGA plot.

[0020] Figure 4 The NMR spectrum of the photocatalytic oxidative coupling of benzylamine to the corresponding imine is shown in the 1H NMR spectrum.

[0021] Figure 5 The NMR spectrum of the photocatalytic oxidative coupling of 3-methylbenzylamine to the corresponding imine is shown in the 1H NMR spectrum.

[0022] Figure 6 The NMR spectrum of the photocatalytic oxidative coupling of 4-bromobenzylamine to the corresponding imine is shown in the 1H NMR spectrum.

[0023] Figure 7 The NMR spectrum of the photocatalytic oxidative coupling of 4-chlorobenzylamine to the corresponding imine is shown in the 1H NMR spectrum.

[0024] Figure 8 The graph shows the change of UV-Vis absorption spectrum over time for the photocatalytic degradation of Rhodamine B.

[0025] Figure 9 The graph shows the change in the degradation rate of Rhodamine B by photocatalysis over time.

[0026] Figure 10 This is a graph showing the cycle performance of Cd-MOF photocatalysts. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. Example

[0028] A method for synthesizing Cd-MOF material involves dissolving 2,6-naphthalenedicarboxylic acid (0.015 mmol, 3.2 mg), an organic ligand (0.015 mmol, 4.5 g), and cadmium nitrate tetrahydrate (0.03 mmol, 9.24 mg) in 2 mL of N,N-dimethylformamide, stirring until homogeneous, sealing in a 10 mL glass bottle, and carrying out a solvothermal reaction (120 °C for 7 days) to obtain Cd-MOF.

[0029] Figure 1 This is a schematic diagram of the crystal structure of the Cd-MOF material mentioned above. Figure 2 The above is a crystal molecular model diagram of the Cd-MOF material.

[0030] Figure 3 The images show the SEM, XRD, BET, and TGA characterizations of the Cd-MOF materials described above.

[0031] The synthesized Cd-MOF material was used in the photocatalytic amine oxidative coupling to prepare imines as described in Examples 2-5, and in the photocatalytic degradation of dyes in wastewater as described in Example 6. Example

[0032] A method for preparing imines by photocatalytic amine oxidative coupling using Cd-MOF, the specific operation steps of which are as follows:

[0033] (1) Add 10 mg of Cd-MOF catalyst to a quartz tube, use 0.1 mmol of benzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and sonicate for 10 min under dark conditions to mix the system evenly.

[0034] (2) At room temperature and in an air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube for 6.5 hours.

[0035] (3) After the reaction was completed, the solid catalyst was separated using a 0.45 μm filter membrane. The liquid product was dried and the yield of the product was evaluated by 1H NMR spectroscopy. The analysis showed that the yield of the corresponding imine was 99%.

[0036] Figure 4 The NMR spectrum of the photocatalytic oxidative coupling of benzylamine to the corresponding imine is shown in the 1H NMR spectrum. Example

[0037] (1) Add 10 mg of Cd-MOF catalyst to a quartz tube, use 0.1 mmol of 3-methylbenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and sonicate for 10 min in the dark to mix the system evenly.

[0038] (2) At room temperature and in an air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube for 6.5 hours.

[0039] (3) After the reaction was completed, the solid catalyst was separated using a 0.45 μm filter membrane, and the liquid product was dried. The yield of the product was evaluated by 1H NMR spectroscopy. The analysis showed that the yield of the corresponding imine was 93%.

[0040] Figure 5 The NMR spectrum of the photocatalytic oxidative coupling of 3-methylbenzylamine to the corresponding imine is shown in the 1H NMR spectrum. Example

[0041] (1) Add 10 mg of Cd-MOF catalyst to a quartz tube, use 0.1 mmol of 4-bromobenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and sonicate for 10 min in the dark to mix the system evenly.

[0042] (2) At room temperature and in an air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube for 6.5 hours.

[0043] (3) After the reaction was completed, the solid catalyst was separated using a 0.45 μm filter membrane. The liquid product was dried and the yield of the product was evaluated by 1H NMR spectroscopy. The analysis showed that the yield of the corresponding imine was 96%.

[0044] Figure 6 The NMR spectrum of the photocatalytic oxidative coupling of 4-bromobenzylamine to the corresponding imine is shown in the 1H NMR spectrum. Example

[0045] (1) Add 10 mg of Cd-MOF catalyst to a quartz tube, use 0.1 mmol of 4-chlorobenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and sonicate for 10 min in the dark to mix the system evenly.

[0046] (2) At room temperature and in an air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube for 6.5 hours.

[0047] (3) After the reaction was completed, the solid catalyst was separated using a 0.45 μm filter membrane. The liquid product was dried and the yield of the product was evaluated by 1H NMR spectroscopy. The analysis showed that the yield of the corresponding imine was 99%.

[0048] Figure 7 The NMR spectrum of the photocatalytic oxidative coupling of 4-chlorobenzylamine to the corresponding imine is shown in the 1H NMR spectrum. Example

[0049] A method for photocatalytic degradation of dyes in wastewater using Cd-MOF, employing the Cd-MOF prepared in Example 1, specifically includes the following steps:

[0050] (1) Disperse 5 mg of Cd-MOF catalyst in 15 mL of 100 mg / mL Rhodamine B aqueous solution, and then stir in the dark for 30 min to reach adsorption equilibrium.

[0051] (2) A 300W xenon lamp was introduced as the light source to photocatalytically degrade Rhodamine B aqueous solution. A certain amount of solution was taken every 5 minutes, centrifuged, and the supernatant was analyzed using a UV-Vis spectrophotometer.

[0052] Figure 8 The UV-Vis absorption spectrum of the photocatalytic degradation of Rhodamine B changes over time. As can be seen from the figure, the Cd-MOF catalyst prepared in this invention exhibits photocatalytic activity and can effectively degrade Rhodamine B.

[0053] Figure 9 This graph shows the degradation rate of Rhodamine B via photocatalytic degradation over time. The horizontal axis represents time, and the vertical axis represents time. t The ratio of / C0, where C0 is the initial concentration of Rhodamine B; C t The concentration of Rhodamine B was measured by sampling every 5 minutes; from Figure 9 As can be seen from the results, under simulated visible light irradiation, the Cd-MOF photocatalyst prepared in Example 1 exhibited a 99% degradation rate of Rhodamine B after 30 minutes, demonstrating excellent performance.

[0054] After the mixture in step (2) is degraded for 30 min, the Cd-MOF photocatalyst is filtered out, washed with water and anhydrous ethanol, dried and recycled. The degradation rate of Rhodamine B in aqueous solution is still up to 90%.

[0055] Figure 10 This is a cycling performance diagram of the Cd-MOF photocatalyst prepared in Example 1 of this invention. Figure 10 As can be seen from the results, the Cd-MOF photocatalyst prepared in Example 1 has good stability and recyclability.

Claims

1. A Cd-MOF material characterized in that, The molecular formula of the compound is C 102 H 98 Cd3N 20 O 12 S6, which belongs to the Monoclinic crystal system, and the unit cell parameters are: a = 45.899(6) Å, b = 17.4621(17) Å, c = 33.535(4) Å, α = 90°, β = 132.477(5) °, γ = 90°.

2. The method for preparing a Cd-MOF material according to claim 1, characterized in that, 2,6-naphthalene dicarboxylic acid, organic ligand 2,5-di(pyridine-4-yl)thiazolo[5,4-d]thiazole and cadmium nitrate tetrahydrate are dissolved in N,N-dimethylformamide, stirred uniformly, sealed in a glass bottle, and subjected to a solvothermal reaction to obtain a Cd-MOF material.

3. The method of claim 2, wherein the Cd-MOF material is prepared by the method comprising the steps of: The molar ratio of 2,6-naphthalene dicarboxylic acid, 2,5-di(pyridine-4-yl)thiazolo[5,4-d]thiazole and cadmium nitrate tetrahydrate is 1:1:2; the molar amount of 2,6-naphthalene dicarboxylic acid to the volume of N,N-dimethylformamide is 3 mmol:400 mL.

4. The method for preparing a Cd-MOF material according to claim 2, characterized in that, The temperature of the solvothermal reaction is 120 DEG C, and the time is 7 days.

5. The application of a Cd-MOF material according to claim 1 in the preparation of imines by photocatalytic amine oxidative coupling.

6. Use according to claim 5, characterized in that, Cd-MOF material is used as a photocatalyst at room temperature, benzylamine and its derivatives are used as raw materials, an organic solvent is added, and a catalytic reaction is carried out under the irradiation of simulated visible light and in an air atmosphere to obtain imines.

7. Use according to claim 6, characterized in that, The raw materials are benzylamine, 3-methylbenzylamine, 4-bromobenzylamine or 4-chlorobenzylamine; and the organic solvent is anhydrous acetonitrile.

8. The application of a Cd-MOF material according to claim 1 in the photocatalytic degradation of dyes in wastewater.

9. Use according to claim 8, characterized in that, Cd-MOF is used as a catalyst in wastewater containing dyes, and after dark reaction adsorption equilibrium, photocatalytic degradation is carried out under the irradiation of visible light.

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