Preparation method of copper-iron bimetal MOFs antibacterial material containing variable price sites

Abstract

The invention discloses a preparation method of a copper-iron bimetal MOFs antibacterial material containing variable price sites, and belongs to the technical field of preparation of inorganic functional materials. The preparation method comprises the following steps: sequentially adding soluble copper salt and iron salt in different proportions into N, N-dimethylformamide to prepare a mixed metal salt solution, then adding terephthalic acid, stirring to fully mix metal ions and organic ligands, then transferring the mixed solution into a high-pressure container, and carrying out heat treatment, so as to obtain the metal-organic hybrid material. The copper-iron bimetallic MOFs all-weather antibacterial material containing the variable-valence Fe site is obtained. Through condition control of experimental parameters, generation of coordinated unsaturated variable valence Fe sites in different proportions can be achieved, the electronic structure of the Fe sites in the bimetallic MOFs is changed, and effective electron transfer between copper and iron sites is promoted. Meanwhile, the process is simple and feasible, short in flow, mild in condition and suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of inorganic functional materials, and in particular relates to a method for preparing a copper-iron bimetallic MOFs antibacterial material containing variable valence sites. Background Art

[0002] Metal-organic frameworks (MOFs) have unique advantages in the development of new antibacterial materials due to their designable porous structure, high specific surface area and adjustable metal active sites. The development of nanoscience has opened up new areas for the research of new materials. Transition metal-based MOFs (such as Fe and Cu-based MOFs) in metal-organic frameworks can achieve broad-spectrum antibacterial effects through mechanisms such as slow release of metal ions and generation of reactive oxygen species (ROS), and have become a current research hotspot.

[0003] Recent studies have shown that iron-based MOFs can II / Fe III The valence cycle can trigger a Fenton-like reaction and continuously generate hydroxyl radicals (·OH), but its antibacterial efficiency is limited by the single active site and electron transfer efficiency. Although copper-based MOFs (such as HKUST-1) have excellent contact bactericidal ability, Cu II The rapid release of Cu can easily lead to the collapse of the material structure. The catalytic bactericidal performance can be significantly improved through the bimetallic synergistic strategy. The iron-copper bimetallic system has shown a unique electronic synergistic effect in the field of catalysis. The introduction of Cu can optimize the electronic structure of Fe and promote redox cycles.

[0004] At present, the preparation methods of bimetallic MOFs mostly adopt physical mixing or post-modification strategies. The uneven distribution of metal sites leads to limited synergistic effects. The traditional preparation process leads to the collapse of the pore structure, and it is difficult to accurately control the oxidation state distribution of the Fe site, resulting in the failure to fully activate the valence-variable activity. Moreover, the antibacterial performance of MOFs catalyzing ROS generation is controlled to a certain extent by light-driven reactions. The antibacterial performance under dark conditions is relatively limited, which limits its antibacterial ability during the day and night cycle and cannot meet the all-weather antibacterial needs. How to construct stable valence-variable Fe sites in bimetallic MOFs, optimize the electronic structure of metal sites, and achieve atomic-level multifunctional synergy with Cu is the key to improving antibacterial performance under all-weather conditions.

[0005] In summary, the development of a simplified and rapid method for preparing a new bimetallic MOFs that can accurately construct variable-valence Fe sites and achieve atomic-level synergy between copper and iron has important scientific value and application prospects for breaking through the performance bottleneck of existing antibacterial materials under dark conditions and achieving all-weather high-efficiency antibacterial properties. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned technology, and propose a method for preparing a copper-iron bimetallic MOFs antibacterial material containing variable valence Fe sites. Through the conditional control of experimental parameters, the generation of coordinated unsaturated variable valence Fe sites of different ratios can be achieved, the electronic structure of the Fe sites in the bimetallic MOFs can be changed, and effective electron transfer between the copper-iron sites can be promoted. Stable variable valence Fe sites are constructed in bimetallic MOFs, the electronic structure of the metal sites is optimized, and atomic-level multifunctional synergy with Cu is achieved, thereby improving the antibacterial performance under all-weather conditions. At the same time, the process is simple and easy, the process is short, and the conditions are mild.

[0007] The technical solution of the present invention is:

[0008] The present invention adopts an improved solvothermal method to prepare a copper-iron bimetallic MOFs antibacterial material containing variable valence sites. First, soluble copper salts and iron salts in different ratios are sequentially added to N,N-dimethylformamide to prepare a mixed metal salt solution, and then terephthalic acid is added. The metal ions and organic ligands are fully mixed by stirring, and then the mixed solution is transferred into a high-pressure container for hydrothermal reaction for a certain period of time. After filtering, washing, and drying, copper-iron bimetallic MOFs nanopowder particles are obtained. After heat treatment under the protection of an inert atmosphere, the copper-iron bimetallic MOFs all-weather antibacterial material containing variable valence Fe sites is obtained.

[0009] The specific preparation steps are:

[0010] A soluble copper salt and iron salt mixed N,N-dimethylformamide solution with a total amount of 2-6 mmol of metal precursor was prepared at room temperature, and 2-6 mmol of terephthalic acid organic ligand was added after magnetic stirring, and the concentration of the metal salt solution was 0.05-0.075 mmol / mL. The magnetic stirring was continued, and the reaction was carried out at a temperature of 100-150 ℃ for 18-22 h, filtered and washed several times with N,N-dimethylformamide and ethanol, centrifuged, and vacuum dried to obtain copper-iron bimetallic MOFs nanoparticles of different particle sizes. The different powder samples obtained after vacuum drying were transferred to ceramic crucibles, and heat treated (hydrothermal reaction) in a high-pressure container to obtain copper-iron bimetallic MOFs all-weather antibacterial materials containing variable valence Fe sites, wherein the molar ratio of copper ions to iron ions was 1-5: 9-1, and the molar ratio of total metal ions to organic ligands was 1-5: 1-3.

[0011] Furthermore, the soluble copper salt and iron salt are copper nitrate trihydrate and ferric chloride hexahydrate.

[0012] Furthermore, the magnetic stirring time is 1 to 30 min, and the magnetic stirring time is continued for 2 to 3 h.

[0013] Furthermore, the vacuum drying is performed at 40-80° C. for 10-15 h.

[0014] Furthermore, the sizes of the different particle sizes are 100 nm~1 um.

[0015] Furthermore, the heat treatment is to place the copper-iron bimetallic MOFs nanoparticles in an Ar atmosphere protected tubular furnace at 250-350° C. for 40-80 min.

[0016] Furthermore, the copper-iron bimetallic MOFs nanoparticles have an octahedral structure.

[0017] Furthermore, the antibacterial rate of the copper-iron bimetallic MOFs all-weather antibacterial material is >93%.

[0018] The characteristics and advantages of the present invention are as follows:

[0019] (1) The present invention utilizes the precisely adjustable structure of Fe-MOF atoms, which is easy to dope with bimetallic materials and generate variable-valence metal sites. Coordinately unsaturated sites are generated through Cu doping and thermal activation, which regulates the electronic structure of Fe sites and promotes effective electron transfer between copper and iron sites.

[0020] (2) The copper-iron bimetallic MOFs containing variable valence Fe sites prepared by the method provided by the present invention can achieve control of the variable valence Fe sites of the copper-iron bimetallic MOFs and all-weather antibacterial properties by adjusting the molar ratio of copper ions and iron ions in the system and the order of their addition, the type of heat treatment protective atmosphere, the heat treatment temperature and time.

[0021] (3) The method provided by the present invention has a simple reaction process, mild conditions, and a short process, and is suitable for industrial production. The reactants and solvents are added to the reactor in proportion for hydrothermal treatment, with fewer operating steps, low equipment requirements, and a simple overall reaction process. The reaction temperature is much lower than that of high-temperature solid-phase reaction (>500°C) or vapor deposition method (>1000°C), the pressure is controllable, and the conditions are mild. The reaction time is much shorter than the days or even weeks of traditional solid-phase reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope photograph of the copper-iron bimetallic MOFs all-weather antibacterial nanoparticles containing variable-valence Fe sites obtained in Example 1 of the present invention.

[0023] Figure 2 This is a transmission electron microscope photograph of the copper-iron bimetallic MOFs all-weather antibacterial nanoparticles containing variable-valence Fe sites obtained in Example 1 of the present invention.

[0024] Figure 3 This is the X-ray diffraction pattern of the copper-iron bimetallic MOFs all-weather antibacterial nanoparticles containing variable-valence Fe sites obtained in Example 1 of the present invention.

[0025] Figure 4 This is a photo of the all-weather antibacterial effect of the copper-iron bimetallic MOFs antibacterial nanoparticles containing variable-valence Fe sites obtained in Example 1 of the present invention on Escherichia coli.

[0026] Figure 5 This is the all-weather antibacterial rate of the copper-iron bimetallic MOFs antibacterial nanoparticles containing variable-valence Fe sites obtained in Example 1 of the present invention.

[0027] Figure 6 This is a scanning electron microscope photograph of the product Fe-MOFs nanoparticles obtained in comparative case 1. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0029] Implementation Case 1

[0030] 60 mL of a mixed solution of ferric chloride hexahydrate and copper nitrate trihydrate with a total amount of 4.0 mmol of metal precursor was prepared at room temperature. The solvent was N,N-dimethylformamide solution, in which the molar ratio of copper ions to iron ions was 1:1. The mixture was stirred magnetically for 30 min. 4.0 mmol of terephthalic acid organic ligand was added under stirring conditions. Stirring was continued for 3 h, and then the temperature was kept at 110 ° C for 20 h. Filtered and washed with N,N-dimethylformamide and ethanol several times, and then vacuum dried at 60 ° C for 12 h. The powder sample obtained after vacuum drying was transferred to a ceramic crucible and kept in an Ar atmosphere protected tube furnace at 300 ° C for 60 min to obtain the final product, copper-iron bimetallic MOFs all-weather antibacterial nanoparticles containing variable valence Fe sites. The scanning electron microscope photos, transmission electron microscope photos and X-ray diffraction patterns of the products and the antibacterial properties are shown in Figure 2. Figure 2-6 As shown, the nanomaterial structure basically maintains an octahedral structure, with evenly distributed pores formed inside, and the average particle size is about 100 nm ~ 500 nm. From the antibacterial test results, it can be seen that the antibacterial rate of the obtained copper-iron bimetallic MOFs is 99.99% at room temperature in the dark for 4 h, and the antibacterial rate is 99.99% under the condition of 30 min of light. The all-weather antibacterial performance is the best, indicating that the copper-iron bimetallic MOFs containing variable valence Fe sites and copper doping (molar ratio of copper ions and iron ions = 1:1) exhibit excellent all-weather antibacterial performance.

[0031] Implementation Case 2

[0032] 60 mL of a mixed solution of ferric chloride hexahydrate and copper nitrate trihydrate with a total amount of 4.0 mmol of metal precursor was prepared at room temperature. The solvent was N,N-dimethylformamide solution, in which the molar ratio of copper ions to iron ions was 3:7. The mixture was stirred magnetically for 30 min, and 4.0 mmol of terephthalic acid organic ligand was added under stirring conditions. The mixture was stirred for 3 h, then kept at 110 ° C for 20 h, filtered and washed with N,N-dimethylformamide and ethanol several times, and then vacuum dried at 60 ° C for 12 h. The powder sample obtained after vacuum drying was transferred to a ceramic crucible and kept in an Ar atmosphere protected tube furnace at 300 ° C for 60 min to obtain the final product of copper-iron bimetallic MOFs nanoparticles containing variable valence Fe sites. The antibacterial rate of the obtained copper-iron bimetallic MOFs in the dark at room temperature for 4 h was 99.57%. It shows that the antibacterial properties of copper-iron bimetallic MOFs containing variable-valence Fe sites and copper doping (molar ratio of copper ions to iron ions = 3:7) are significantly improved under room temperature dark conditions.

[0033] Implementation Case 3

[0034] 60 mL of a mixed solution of ferric chloride hexahydrate and copper nitrate trihydrate with a total amount of 4.0 mmol of metal precursor was prepared at room temperature. The solvent was N,N-dimethylformamide solution, in which the molar ratio of copper ions to iron ions was 1:3. The mixture was stirred magnetically for 30 min, and 4.0 mmol of terephthalic acid organic ligand was added under stirring conditions. The mixture was stirred for 3 h, then kept at 110 ° C for 20 h, filtered and washed with N,N-dimethylformamide and ethanol several times, and then vacuum dried at 60 ° C for 12 h. The powder sample obtained after vacuum drying was transferred to a ceramic crucible and kept in an Ar atmosphere protected tube furnace at 300 ° C for 60 min to obtain the final product of copper-iron bimetallic MOFs nanoparticles containing variable valence Fe sites. The antibacterial rate of the obtained copper-iron bimetallic MOFs in the dark at room temperature for 4 h was 98.31%. This indicates that the antibacterial properties of copper-iron bimetallic MOFs containing variable-valence Fe sites and copper doping (molar ratio of copper ions to iron ions = 1:3) are improved under room temperature dark conditions.

[0035] Implementation Case 4

[0036] 60 mL of a mixed solution of ferric chloride hexahydrate and copper nitrate trihydrate with a total amount of 4.0 mmol of metal precursor was prepared at room temperature. The solvent was N,N-dimethylformamide solution, in which the molar ratio of copper ions to iron ions was 1:9. The mixture was stirred magnetically for 30 min, and 4.0 mmol of terephthalic acid organic ligand was added under stirring conditions. The mixture was stirred for 3 h, then kept at 110 ° C for 20 h, filtered and washed with N,N-dimethylformamide and ethanol several times, and then vacuum dried at 60 ° C for 12 h. The powder sample obtained after vacuum drying was transferred to a ceramic crucible and kept in an Ar atmosphere protected tube furnace at 300 ° C for 60 min to obtain the final product of copper-iron bimetallic MOFs nanoparticles containing variable valence Fe sites. The antibacterial rate of the obtained copper-iron bimetallic MOFs in the dark at room temperature for 4 h was 93.63%. This indicates that the antibacterial properties of copper-iron bimetallic MOFs containing variable-valence Fe sites and copper doping (molar ratio of copper ions to iron ions = 1:9) are improved under room temperature dark conditions.

[0037] Comparative Case 1

[0038] 60 mL of a mixed solution of ferric chloride hexahydrate and copper nitrate trihydrate with a total amount of 4.0 mmol of metal precursor was prepared at room temperature. The solvent was N,N-dimethylformamide solution, in which the molar ratio of copper ions to iron ions was 0:10. The mixture was stirred magnetically for 30 min. 4.0 mmol of terephthalic acid organic ligand was added under stirring conditions. Stirring was continued for 3 h. The mixture was then kept at 110 °C for 20 h. The mixture was filtered and washed several times with N,N-dimethylformamide and ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the final product, Fe-MOFs. The scanned photo of the product is shown in Figure 2. Figure 1 As shown, the Fe-MOFs structure is a smooth octahedral structure with clear and orderly edges and corners and an average particle size of about 500 nm~1 um. From the antibacterial test results, it can be seen that the antibacterial rate of the obtained Fe-MOFs at room temperature in the dark for 4 h is 54.39%, indicating that the single metal Fe-MOFs without variable valence Fe sites and copper doping have poor antibacterial effect at room temperature in the dark.

[0039] The Fe-MOFs (MIL-100(Fe)) synthesized by the solvothermal method in the prior art showed an antibacterial rate of 42.5% against Escherichia coli in a dark environment at room temperature for 24 hours; the antibacterial rate of physically mixed Fe / Cu bimetallic materials (mass ratio 1:1) against Escherichia coli in a dark environment at room temperature for 24 hours was 54.2%. In contrast, the present invention, by constructing a copper-iron bimetallic MOFs all-weather nano-antibacterial material containing variable valence Fe sites, can achieve an antibacterial rate of more than 93% against Escherichia coli in a dark environment at room temperature for only 4 hours, significantly shortening the action time and significantly improving the antibacterial rate under dark conditions, which is significantly superior to the prior art.

Claims

1. A method for preparing a copper-iron bimetallic MOFs antibacterial material containing variable valence sites, characterized in that: A mixed N,N-dimethylformamide solution of soluble copper salt and iron salt with a total amount of 2-6 mmol of metal precursor was prepared at room temperature, and 2-6 mmol of terephthalic acid organic ligand was added after magnetic stirring. The concentration of the metal salt solution was 0.05-0.075 mmol / mL, and magnetic stirring was continued. The reaction was carried out at a temperature of 100-150 ℃ for 18-22 h, and the mixture was filtered and washed several times with N,N-dimethylformamide and ethanol, centrifuged, and vacuum dried to obtain copper-iron bimetallic MOFs nanoparticles of different particle sizes. The different powder samples obtained after vacuum drying were transferred to ceramic crucibles respectively, and heat treated in a high-pressure container to obtain copper-iron bimetallic MOFs all-weather antibacterial materials containing variable-valence Fe sites, in which the molar ratio of copper ions to iron ions was 1-5: 9-1, and the molar ratio of total metal ions to organic ligands was 1-5: 1-3.

2. The method for preparing an antibacterial material according to claim 1, characterized in that: The soluble copper salt and iron salt are copper nitrate trihydrate and ferric chloride hexahydrate.

3. The method for preparing an antibacterial material according to claim 1, characterized in that: The magnetic stirring time is 1 to 30 min, and the magnetic stirring time is continued for 2 to 3 h.

4. The method for preparing an antibacterial material according to claim 1, characterized in that: The vacuum drying is performed at 40-80° C. for 10-15 h.

5. The method for preparing an antibacterial material according to claim 1, characterized in that: The sizes of the different particle sizes are 100nm~1 um.

6. The method for preparing an antibacterial material according to claim 1, characterized in that: The heat treatment is to place the copper-iron bimetallic MOFs nanoparticles in an Ar atmosphere protection tube furnace at 250-350° C. for 40-80 min.

7. The method for preparing an antibacterial material according to claim 1, characterized in that: The copper-iron bimetallic MOFs nanoparticles have an octahedral structure.

8. The method for preparing an antibacterial material according to claim 1, characterized in that: The antibacterial rate of the copper-iron bimetallic MOFs all-weather antibacterial material is >93%.

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