A metal complex and its preparation method and its application in photocatalytic antibacterial

Abstract

The invention discloses a metal complex and a preparation method thereof and its application in photocatalytic antibacterial, belonging to the technical field of photocatalytic material synthesis. The invention uses pyridine-2-methylamine, pyridine-2-formaldehyde and metal chloride as raw materials, and prepares the metal complex by a hydrothermal method. The raw materials required are easy to obtain, the equipment and process are simple and easy to operate, the yield is high, and the obtained metal complex exhibits good photocatalytic antibacterial activity under visible light and LED light, and has good antibacterial activity against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus, showing a broad spectrum of sterilization, and has a wide range of practical value and application research prospects in production and life.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalytic material synthesis, and specifically relates to a metal complex and a preparation method thereof and application thereof in photocatalytic antibacterial properties. Background Art

[0002] Traditional sterilization techniques, such as high temperature sterilization, alcohol disinfectant treatment, chlorine disinfectant treatment, ultraviolet light treatment, quaternary ammonium disinfectant treatment, phenol disinfectant treatment, ozone oxidation treatment, etc., can effectively kill bacteria, but the disinfection work is not only time-consuming and labor-intensive, but also produces secondary pollution and requires ventilation. In 1985, Matsunaga et al. first studied the antibacterial and inactivation properties of Pt / TiO2 under visible light. Since then, photocatalytic sterilization, a more efficient and environmentally friendly technology, has received attention from a large number of scientific researchers. Since the strongest light in the solar spectrum is mainly concentrated in the visible region, it is of great significance to design a photocatalytic antibacterial material that can make full use of solar energy in the visible region. Diseases caused by pathogenic microorganisms bring great harm to humans, so there is a greater need for an antibacterial catalyst that can remove harmful bacteria and other pathogens while ensuring the balance of ecological system and human health.

[0003] Transition metal elements such as copper, manganese, zinc, iron, cobalt, nickel, etc. have a variety of coordination properties, which make them show a variety of structural characteristics from simple one-dimensional (1D) polymers to complex three-dimensional (3D) metal organic frameworks. Multifunctional materials represented by transition metal coordination polymers have attracted more and more attention due to their novel structure and wide application prospects in catalysis, optics, separation, antibacterial and other aspects. There are relatively few reports on the antibacterial aspects of transition metal complexes in the prior art. For example, patent CN 114191326A discloses a zinc complex oral care product containing mogroside B, but it has only a little anti-inflammatory and antibacterial effect, and has no effect of killing bacteria; a zinc complex solid agent disclosed in patent CN 111892719A has a certain antibacterial effect on Escherichia coli and Staphylococcus aureus, but its antibacterial circle effect is general; the brass metal complex disclosed in patent CN 112442051A is mainly used to inhibit citrus canker pathogens, and it is used to disinfect crop viruses, but it has certain harm to the human body. Therefore, coordination polymer materials based on transition metal elements such as copper, manganese, zinc, iron, cobalt, nickel and other metals are a new type of material worthy of development, and they have more outstanding performance in places such as hospitals, stations, warehouses, etc. where rapid sterilization and disinfection are required. Summary of the invention

[0004] The purpose of the present invention is to provide a metal complex and a preparation method thereof and application thereof in photocatalytic antibacterial properties.

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

[0006] A metal complex, the structural formula of which is as follows:

[0007] , where M=Mn, Fe, Cu, Zn, Ni, Co.

[0008] The preparation method of the metal complex comprises the following steps:

[0009] (1) At room temperature, add pyridine-2-methylamine, pyridine-2-carboxaldehyde and metal chloride to acetonitrile and stir thoroughly to obtain a uniform solution;

[0010] (2) pouring the uniform solution obtained in step (1) into a hydrothermal reaction kettle, sealing the reaction kettle, and performing a hydrothermal reaction at a certain temperature;

[0011] (3) After the reaction solution obtained in step (2) is cooled, the solution is collected, washed, centrifuged, and dried at normal pressure to obtain the metal complex.

[0012] Furthermore, in step (1), the molar ratio of pyridine-2-methylamine, pyridine-2-carboxaldehyde and metal chloride is 0.1:1:0.5.

[0013] Furthermore, the temperature of the hydrothermal reaction in step (2) is 60°C~140°C, and the time is 48 h.

[0014] Furthermore, the temperature of the normal pressure drying in step (3) is 60°C to 200°C.

[0015] The metal complex can use visible light as the only driving force for reaction and is used for photocatalytic antibacterial.

[0016] The significant advantages of the present invention are:

[0017] (1) The preparation process of the present invention is simple, the preparation conditions are mild, the raw materials are cheap, the energy consumption is low, and the yield is high.

[0018] (2) The catalyst obtained by the present invention exhibits good antibacterial and sterilization properties in the photocatalytic antibacterial process, especially good antibacterial effects on Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus, showing good broad-spectrum sterilization and is suitable for warm, humid, and bacteria-prone environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a physical photo of the metal complex prepared in Example 1.

[0020] Figure 2This is a schematic diagram of the structural characterization of the metal complex prepared in Example 1 measured by in-situ infrared spectrometer.

[0021] Figure 3 The antibacterial kinetic curves of the metal complex in Example 2 against Escherichia coli (a) and Staphylococcus aureus (b).

[0022] Figure 4 The inhibition zone effect diagram of Escherichia coli (a) and Staphylococcus aureus (b) after being cultured for 24 hours in the presence of the metal complex film in Example 4.

[0023] Figure 5 This is the SEM image of Gram-negative bacteria Escherichia coli before and after the reaction in Example 5.

[0024] Figure 6 : These are SEM images of Gram-positive bacteria Staphylococcus aureus before and after the reaction in Example 5.

[0025] Figure 7 This is the antibacterial kinetic curve of different metal complexes against Escherichia coli in Example 6. DETAILED DESCRIPTION

[0026] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0027] Example 1

[0028] At room temperature, 0.1mmol pyridine-2-methylamine, 1mmol pyridine-2-carboxaldehyde and 0.5mmol zinc chloride were added to 10mL acetonitrile, stirred evenly and then the resulting solution was placed in a reaction kettle, sealed and placed in a hydrothermal oven at 80°C for 48h, and after cooling to room temperature, the mixture was collected, washed with acetonitrile, centrifuged, and dried at 80°C under normal pressure to obtain a metal zinc ion complex with photocatalytic antibacterial function. The obtained sample is shown in the photo. Figure 1 .

[0029] Figure 2 This is the in-situ infrared spectrum of the obtained sample. -1 The wavelength belongs to (OH), 3050cm -1 The wavelength belongs to Cl-Zn, 1500cm -1 The wavelength belongs to C=N, which proves the successful preparation of the complex.

[0030] Example 2

[0031] (1) Inoculate E. coli into 2 mL of LB broth and culture in a 37°C constant temperature incubator for 24 h to obtain E. coli culture liquid. Dilute the cultured E. coli culture liquid to 10% with phosphate buffered saline (PBS solution). 8-9 cfu / mL, transfer 4 mL to the reactor, and then add 36 mL PBS. At this time, the concentration of bacteria is about 10 7 cfu / mL, add a magnet, and stir at a constant speed of 450 r / min. After stirring evenly, weigh 20 mg of the metal zinc ion complex obtained in Example 1 and put it into the reactor, turn on the xenon lamp (λ≥400 nm) 32 cm above the reactor, turn on the fan to dissipate heat from the reactor, and remove the effect of the heat energy of the xenon lamp on the reaction. Take 0.5 mL of the reaction solution every 1 h and add it to a small test tube containing 4.5 mL of PBS solution. Dilute it to a certain multiple according to the experimental requirements and take 0.5 mL and transfer it to the culture dish. Pour agar cooled to 40 ℃~45 ℃ in the culture dish, stir to evenly disperse the bacterial solution in the agar, and put it into a constant temperature incubator at 37 ℃ after the agar solidifies. After culturing for 24 h, take it out and use the plate count method to calculate the colonies.

[0032] (2) The Staphylococcus aureus strain was inoculated into 2 mL of LB broth and cultured in a constant temperature incubator at 37°C for 24 h to obtain a Staphylococcus aureus bacterial solution. The remaining steps are the same as those in (1) of this embodiment.

[0033] Figure 3 The antibacterial kinetic data of Gram-negative bacteria Escherichia coli (a) and Gram-positive bacteria Staphylococcus aureus (b) under visible light blank control, darkness, visible light and LED light conditions are shown in the figure. It can be seen that the bacteria will not die under visible light irradiation conditions only, and there is no antibacterial effect under dark conditions. However, the antibacterial efficiency of Escherichia coli reaches 100% after irradiation with visible light for 3 hours in the culture medium containing the complex, and the antibacterial efficiency can reach 82.1% after irradiation with LED light for 4 hours; the antibacterial efficiency of Staphylococcus aureus reaches 100% after irradiation with visible light for 4 hours in the culture medium containing the complex, and the antibacterial efficiency reaches 74.3% after irradiation with LED light for 4 hours.

[0034] Example 3

[0035] The metal zinc ion complex obtained in Example 1 was fully dissolved in ethanol, and then evenly coated on a clean 1 cm×1.5 cm glass slide, and dried in an oven at normal pressure and 60° C. to obtain a loaded metal complex film.

[0036] Example 4

[0037] (1) Inoculate E. coli into 2 mL LB broth and culture in a 37°C incubator for 24 h. Then dilute to 10% with PBS solution. 8-9 cfu / mL, take 0.5 mL and add it into a small test tube containing 4.5 mL PBS solution to dilute its concentration to 10 3 cfu / mL. Take 0.5 mL of the diluted bacterial solution and transfer it to a dry and clean culture dish, pour in about 40 mL of nutrient agar cooled to 40°C~45°C, and mix them evenly; put the metal complex film prepared in Example 3 in the center of the culture dish, and turn on the xenon lamp (λ≥400 nm) and the fan 32 cm above the culture dish, and irradiate the culture dish for two hours; after the reaction is completed, wrap the culture dish with plastic wrap and place it in a constant temperature incubator for 24 h.

[0038] (2) Inoculate Staphylococcus aureus into 2 mL LB broth and culture in a 37°C incubator for 24 h. Then dilute to 10% with PBS solution. 8-9 The remaining operations were the same as those in (1) of this embodiment.

[0039] Figure 4 The following are the inhibition zone effects of Escherichia coli (a) and Staphylococcus aureus (b) after culturing for 24 hours in the presence of metal complex film. As can be seen from the figure, the diameter of the inhibition zone of Escherichia coli is 4 cm, and the diameter of the inhibition zone of Staphylococcus aureus is 3.6 cm, indicating that the metal complex film has a good antibacterial effect.

[0040] Example 5

[0041] The bacterial solution before and after the reaction of Example 2 was collected, frozen with 2.5% glutaraldehyde for 12 h, and then centrifuged and washed with 25%, 50%, 75%, and 100% ethanol solutions, respectively. After being placed in a freeze dryer and dried, the obtained bacterial samples were tested by scanning electron microscopy.

[0042] Figure 5 , 6 The scanning electron microscope images of Escherichia coli and Staphylococcus aureus before and after the reaction are shown in Figure 1. As can be seen from the figure, the bacterial cell membrane is broken after the reaction, proving that the bacteria have died.

[0043] Example 6

[0044] According to the same synthesis method as in Example 1, the zinc chloride used was replaced with an equimolar amount of manganese chloride, ferric chloride, cobalt chloride, nickel chloride and copper chloride to prepare complexes containing different metal centers. Then, according to the method described in Example 2, an Escherichia coli inactivation test was carried out under visible light. The results are shown in FIG. Figure 7 .

[0045] Depend on Figure 7 By comparison, it can be seen that zinc complex has the highest antibacterial activity, followed by copper complex and cobalt complex, while manganese complex, iron complex and nickel complex have poor antibacterial activity.

[0046] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a metal complex, characterized in that: The following steps are involved: (1) At room temperature, add pyridine-2-methylamine, pyridine-2-carboxaldehyde and metal chloride to acetonitrile and stir to obtain a uniform solution; (2) subjecting the homogeneous solution obtained in step (1) to a hydrothermal reaction at a certain temperature; (3) After the reaction solution obtained in step (2) is cooled, the solution is collected, washed, centrifuged, and dried at normal pressure to obtain the metal complex; In step (1), the molar ratio of pyridine-2-methylamine, pyridine-2-carboxaldehyde and metal chloride is 0.1:1:0.

5.

2. The method for preparing a metal complex according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (2) is 60°C~140°C, and the time is 48 h.

3. The method for preparing a metal complex according to claim 1, characterized in that: The temperature of the normal pressure drying in step (3) is 60°C to 200°C.

4. Use of the metal complex prepared by the method as claimed in claim 1 in photocatalytic antibacterial.

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