Method for one-pot synthesis of metal organic framework material by hydrothermal method and photocatalytic application of metal organic framework material

Abstract

The invention belongs to the field of environmental protection, and discloses a method for one-pot synthesis of a metal organic framework material by a hydrothermal method and photocatalytic application of the metal organic framework material. The method for one-pot synthesis of the metal organic framework material comprises the following steps: dispersing a ligand 4, 4 '-(benzo [c] [1, 2, 5] thiadiazole-4, 7-diyl) diphenylamine, pyrazole-4-formaldehyde and a copper salt in an acetic acid or trifluoroacetic acid solution of water, then sealing and heating, and obtaining the metal organic framework material after the reaction is completed. The prepared metal organic framework material can be used as a high-efficiency composite heterogeneous photocatalyst, is good in repeatability, is simple in synthesis process flow, is high in operability, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection, and particularly relates to a method for synthesizing a metal organic framework material in one pot by a hydrothermal method and a photocatalytic application thereof. Background Art

[0002] Metal-organic frameworks (MOFs) are a class of crystalline porous materials self-assembled from metal ions / clusters and organic linkers. Due to their tunable pore size, large specific surface area, and ease of functionalization, MOF materials have been widely studied in various fields such as energy storage, sensing, and drug delivery. The synthesis of MOFs usually requires the use of large amounts of high-boiling organic solvents, such as N,N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO), which can have serious environmental impacts when scaling up production. In addition, current practices for functionalizing MOFs usually require pre-installation or post-modification strategies, which may greatly increase the complexity of the synthesis process. Therefore, there is an urgent need to create MOFs with structural diversity in a sustainable manner. In addition, organic photosensitizers can act as building blocks and be built into the framework of MOFs to form heterogeneous photosensitizer molecules. Benzothiadiazole (BT) units have been used in the synthesis of various heterogeneous photocatalysts due to their excellent light absorption efficiency, strong electron-withdrawing ability, and photochemical activity.

[0003] Although a variety of building blocks and connection methods have been reported in the MOFs currently under development, almost all of them are prepared by pre-synthesizing organic ligands and then preparing them through solvothermal synthesis, which is usually time-consuming and harmful to the environment. Using water instead of organic solvents as the reaction medium for the synthesis of MOFs is an attractive option, but the raw materials are not soluble enough in water. On the other hand, hydrothermal synthesis of MOFs is a mature technology. Compared with solvothermal chemistry, hydrothermal chemistry has the advantages of low raw material cost, low equipment cost, low energy consumption, high production efficiency and low environmental impact in terms of economy. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to provide a method for one-pot synthesis of metal organic framework materials by hydrothermal method. We decompose the organic linker into amine and aldehyde to increase its solubility in water, so that MOF with imine organic linker can be co-assembled through dynamic covalent bonds and coordination bonds at the same time. This synthetic strategy can also improve the efficiency of MOF generation and simplify the reaction steps by eliminating the necessity of complex organic linkers.

[0005] Another object of the present invention is to provide a metal organic framework material prepared by the above method.

[0006] Another object of the present invention is to provide application of the above metal organic framework material in photocatalytic reaction.

[0007] The purpose of the present invention is achieved through the following solutions:

[0008] A method for preparing a metal organic framework material for photocatalytic reaction comprises the following steps:

[0009] The ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine, pyrazole-4-carboxaldehyde and copper salt are dispersed in an acid solution of water, and then sealed and heated for reaction. After the reaction is completed, a metal organic framework material is obtained.

[0010] Furthermore, the molar ratio of the pyrazole-4-carboxaldehyde, 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine and copper salt is 2:1:(1-2).

[0011] Furthermore, the copper salt is at least one of cuprous oxide, cupric nitrate, cupric acetate, copper sulfate, etc., preferably cuprous oxide.

[0012] Furthermore, the aqueous acid solution is an acid aqueous solution, wherein the acid is one of acetic acid or trifluoroacetic acid, the acid concentration is 1.0M-17.5M, and the amount of the aqueous acid solution meets the requirement that 1.0-18mL of aqueous acid solution is added for every 0.20mmol of copper salt.

[0013] Furthermore, the temperature of the sealed heating reaction is 80-140° C., and the time of the heating reaction is 1-7 days.

[0014] Furthermore, after the reaction is completed, the material obtained is purified by centrifugation, extraction and drying, wherein the organic reagent used for extraction is ethanol, so as to remove monomers or small molecule complexes that have not reacted completely.

[0015] The metal organic framework material (named JNU-301) used as a photocatalyst prepared by the method of the present invention has a specific reaction route as follows: Fig.11 shown.

[0016] A metal organic framework material prepared by the above method has a structure as shown below:

[0017]

[0018] The use of the metal organic framework material in a photocatalytic reaction is preferably in a photocatalytic copper-mediated alkyne coupling reaction, and more preferably in a photocatalytic copper-mediated alkynylation of tetrahydroisoquinoline compounds.

[0019] A method for photocatalytic copper-mediated tetrahydroisoquinoline alkyne coupling comprises the following steps:

[0020] The tetrahydroisoquinoline compound, alkyne and the above-mentioned metal organic framework material are mixed in a solvent, and then stirred to react under light, thereby achieving the alkynylation of the tetrahydroisoquinoline compound.

[0021] The tetrahydroisoquinoline compound is 2-phenyl-1,2,3,4-tetrahydroisoquinoline;

[0022] The alkyne is at least one of phenylacetylene, 4-methylphenylacetylene, 3-methylphenylacetylene, 4-methoxyphenylacetylene, 4-fluorophenylacetylene, 3-fluorophenylacetylene, 3,3-dimethyl-1-butyne, 3-methyl-1-butyne, ethynylcyclohexane, 1-ethynyl-3,5-dimethoxybenzene, 3-ethynylpyridine and 4-ethynylpyridine;

[0023] The molar ratio of the tetrahydroisoquinoline compound to the alkyne is 1:1-2; the amount of the metal organic framework material is such that 2-10 mg of the metal organic framework material is added for every 0.1 mmol of the tetrahydroisoquinoline compound.

[0024] The solvent is at least one of acetonitrile and methanol, and the amount of the solvent is such that 1-5 mL of the solvent is used for every 0.1 mmol of the tetrahydroisoquinoline compound;

[0025] The illumination is preferably 12-90W blue light LED; the stirring time is 5-48h; and the stirring speed is preferably 200-1500rpm.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The metal organic framework material successfully synthesized by the present invention has high crystallinity and porosity according to powder X-ray diffraction and nitrogen adsorption-desorption.

[0028] 2. When the hydrothermal method provided by the present invention is used to prepare metal organic framework materials, the use of organic solvents is eliminated, thereby greatly reducing the impact on the environment and simplifying the reaction steps.

[0029] 3. The one-pot synthesis method provided by the present invention simplifies the reaction steps when preparing metal organic framework materials.

[0030] 4. The present invention uses a hydrothermal method, which can be synthesized in batches with good repeatability. At the same time, the synthesis process is simple, operability is strong, and it has broad application prospects.

[0031] 5. According to experimental values, the metal organic framework material prepared by the present invention can be used as a highly efficient composite heterogeneous photocatalyst.

[0032] 6. The catalyst of the present invention can be used at least 3 times after being dried after washing after centrifugation, and the yield of the corresponding product is not reduced. It is important that the repeatability is good, the synthesis process is simple, the operability is strong, and it has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The powder XRD diffraction comparison spectrum of JNU-301 prepared in Example 1 and its raw material;

[0034] Figure 2 A comparison diagram of the PXRD pattern of JNU-301 prepared in Example 1 and the PXRD patterns of different simulated stacking structures;

[0035] Figure 3 is the nitrogen adsorption isotherm of JNU-301 prepared in Example 1;

[0036] Figure 4 The solid-state UV-visible diffuse emission pattern of JNU-301 prepared in Example 1;

[0037] Figure 5 The Eg diagram of JNU-301 prepared in Example 1 is obtained by Tauc plot based on the solid-state UV-visible diffuse emission data;

[0038] Figure 6 This is the electromagnetic paramagnetic resonance spectrum of superoxide radical anions produced by JNU-301 prepared in Example 1;

[0039] Figure 7 This is the electromagnetic paramagnetic resonance spectrum of singlet oxygen produced by JNU-301 prepared in Example 1;

[0040] Figure 8 is a reaction diagram of the visible light-catalyzed alkyne coupling of Example 2;

[0041] Fig. 9 This is a graph showing the cyclic catalytic conversion rate of the visible light-catalyzed phenylacetylene coupling reaction in Example 2.

[0042] Fig.10 The powder XRD diffraction pattern of JNU-301 prepared in Example 2 after three cycles of photocatalytic copper-mediated alkyne coupling reaction.

[0043] Fig.11 The invention discloses a specific reaction route for a metal organic framework material (named as JNU-301) used as a photocatalyst prepared by the method of the invention. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially. The present invention uses gas phase-mass spectrometry to measure the conversion rate of the obtained organic product.

[0045] Example 1: Preparation of metal organic framework materials

[0046] Preparation of JNU-301: Organic ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine (71.6 mg, 0.225 mmol), Cu 2 O (32.2 mg, 0.225 mmol) and 4-formylpyrazole (Pz-CHO, 43.2 mg, 0.45 mmol) were dispersed in 6 mL of acetic acid solution (4 M) in water; transferred to a 20 mL hard glass bottle, sealed and kept at 100 ° C for 7 days, cooled to room temperature, centrifuged, and the obtained solid was extracted with anhydrous ethanol as a solvent to remove monomers or small molecular complexes that were not completely reacted to obtain a brown powder, which was then placed in a vacuum drying oven at a temperature of 120 ° C for 24 hours to remove the solvent molecules, thereby obtaining the metal organic framework material, referred to as JNU-301.

[0047] The prepared JNU-301 was characterized as follows:

[0048] (1) Powder X-ray diffraction characterization of purity

[0049] The crystallinity of JNU-301 was characterized by X-ray powder diffraction (PXRD). Figure 2 It can be seen that the experimentally measured PXRD spectrum of JNU-301 is consistent with the peak position of the simulated AA stacking structure, proving that JNU-301 has been successfully synthesized.

[0050] (2) Characterization of Porosity by Nitrogen Adsorption and Desorption

[0051] The nitrogen adsorption test of 1 was carried out at 77K using a gas adsorption instrument. Figure 3 It can be seen that JNU-301 has obvious porosity and its specific surface area (BET) is 439m 2 g -1 .

[0052] (3) Solid UV-Vis diffuse reflectance characterization of absorption range and band gap width

[0053] UV-visible diffuse reflectance data were collected on a Shimadzu UV3600 Plus, with continuous scanning in the range of 200 to 800 nm. The optical band gap of JNU-301 was estimated based on the Tauc plot method. Figure 4 is the UV-visible diffuse reflectance of JNU-301, from Figure 5 It can be seen that the absorption range of the synthesized JNU-301 is within the range of 200 to 600 nm, and the optical band gap is 2.28 eV.

[0054] (4) Electromagnetic resonance spectroscopy characterization of JNU-301's ability to generate reactive oxygen species under visible light

[0055] Electron paramagnetic resonance (EPR) signals were recorded on a Bruker A300 spectrometer (Germany) at room temperature under visible light irradiation with a blue LED (400-470 nm). Figure 6 and Figure 7 The EPR data of JNU-301 is Figure 6 and Figure 7 It can be seen that under visible light irradiation, JNU-301 can produce singlet oxygen ( 1 O 2 ) and superoxide radical anion (O 2 ·- ).

[0056] Example 2: JNU-301 for visible light-catalyzed copper-mediated alkynylation of tetrahydroisoquinoline

[0057] Under 12 W blue LED light, a mixture of 2-phenyl-1,2,3,4-tetrahydroisoquinoline (19.0 μL, 0.10 mmol), alkyne (0.10 mmol) and JNU-301 (5.0 mg) was placed in CH 3 CN (1.0 mL) and stirred at room temperature under 12 W blue LED irradiation for 16 h. Then, the supernatant was analyzed by gas chromatography-mass spectrometry (GC-MS) and the conversion rate was calculated.

[0058] Figure 8 The reaction diagram of Example 2 in the visible light catalytic alkyne coupling is shown in FIG. Figure 8 It can be seen that the substrate range of terminal alkynes was explored using the optimized conditions. When JNU-301 was used as a photocatalyst, aromatic alkynes, aliphatic alkynes, and pyridyl alkynes containing electron-donating or electron-withdrawing groups could be used for the α-acetylation reaction of tetrahydroisoquinoline, and the conversion rate of the cross-coupling products produced was moderate to good.

[0059] Fig. 9This is a graph of the cyclic catalytic conversion rate of the visible light catalytic phenylacetylene coupling reaction of Example 2. After being recycled for 3 times, the yield of the corresponding product did not decrease. Fig.10 This is the powder XRD diffraction pattern of JNU-301 prepared in Example 2 after three cycles of photocatalytic copper-mediated alkyne coupling reaction. It can be seen that the structure of JNU-301 is basically unchanged before and after the reaction.

[0060] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a metal organic framework material for photocatalytic reaction, characterized in that The following steps are involved: The ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine, pyrazole-4-carboxaldehyde and copper salt are dispersed in an acid solution of water, and then sealed and heated for reaction. After the reaction is completed, a metal organic framework material is obtained.

2. The method for preparing a metal organic framework material for photocatalytic reaction according to claim 1, characterized in that: The copper salt is at least one of cuprous oxide, copper nitrate, copper acetate and copper sulfate.

3. The method for preparing a metal organic framework material for photocatalytic reaction according to claim 1, characterized in that: The molar ratio of the pyrazole-4-carboxaldehyde, 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine and copper salt is 2:1:(1-2).

4. The method for preparing a metal organic framework material for photocatalytic reaction according to claim 1, characterized in that: The aqueous acid solution is an acid aqueous solution, wherein the acid is one of acetic acid or trifluoroacetic acid, the acid concentration is 1.0M-17.5M, and the amount of the aqueous acid solution meets the requirement that 1.0-18mL of aqueous acid solution is added for every 0.20mmol of copper salt.

5. The method for preparing a metal organic framework material for photocatalytic reaction according to claim 1, characterized in that: The sealing heating temperature is 80-140° C., and the heating time is 1-7 days.

6. A metal organic framework material prepared by the method according to any one of claims 1 to 5, wherein the structural formula is as follows:

7. Use of the metal organic framework material according to claim 6 in photocatalytic reactions.

8. Use of the metal organic framework material according to claim 6 in a photocatalytic copper-mediated alkyne coupling reaction.

9. A method for photocatalytic copper-mediated alkyne coupling of tetrahydroisoquinoline compounds, characterized in that The following steps are involved: The tetrahydroisoquinoline compound, alkyne and the metal organic framework material according to claim 6 are mixed in a solvent and then stirred for reaction under light, thereby achieving alkynylation of the tetrahydroisoquinoline compound.

10. The method of photocatalytic copper-mediated alkyne coupling of tetrahydroisoquinoline compounds according to claim 9, characterized in that: The tetrahydroisoquinoline compound is 2-phenyl-1,2,3,4-tetrahydroisoquinoline; The alkyne is at least one of phenylacetylene, 4-methylphenylacetylene, 3-methylphenylacetylene, 4-methoxyphenylacetylene, 4-fluorophenylacetylene, 3-fluorophenylacetylene, 3,3-dimethyl-1-butyne, 3-methyl-1-butyne, ethynylcyclohexane, 1-ethynyl-3,5-dimethoxybenzene, 3-ethynylpyridine and 4-ethynylpyridine; The molar ratio of the tetrahydroisoquinoline compound to the alkyne is 1:1-2; the amount of the metal organic framework material is such that 2-10 mg of the metal organic framework material is added for every 0.1 mmol of the tetrahydroisoquinoline compound; The solvent is at least one of acetonitrile and methanol; The illumination is 12-90W blue light LED; the stirring time is 5-48h.

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