Visible light response type antibacterial complex and preparation method and use thereof

Abstract

The application belongs to the field of antibacterial agent material preparation, and discloses a visible light response type antibacterial complex and a preparation method and application thereof. The imidazole ligand containing a photosensitive group is first synthesized, and then is coordinated with a metal to synthesize the complex. The synthesized complex has absorption in the visible light region of 350-723 nm, has good light absorption effect on light, has low cytotoxicity, has broad-spectrum bactericidal properties under light, and has good antibacterial effect on gram-positive bacteria and gram-negative bacteria under sunlight.

Description

Technical Field

[0001] This invention relates to the field of antibacterial agent material preparation, specifically a visible light responsive antibacterial complex, its preparation method, and its uses. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Antibiotic overuse leading to bacterial resistance and environmental pollution has become a major challenge in the global healthcare field. Photoactivated antimicrobial materials, due to their excellent bactericidal ability and low bacterial resistance, have become a hot research topic in the antimicrobial field.

[0004] Imidazole and its derivatives are a class of natural drug building blocks widely found in nature. Imidazole metal complexes have broad applications in the inhibition of tumors and bacteria. However, complexes constructed using imidazole and its derivatives as ligands exhibit weak light absorption and photoresponse capabilities, significantly limiting their photoactivated antibacterial activity. Therefore, rationally designing the structural units of imidazole derivatives to enhance the light absorption capacity of imidazole complexes, thereby improving their antibacterial activity, is of great significance for the development of novel antibacterial materials.

[0005] Fluoroboropyrrole and its derivatives (BODIPY), possessing advantages such as a large molar coefficient, large Stokes shift, and high fluorescence quantum yield, are among the photosensitizers commonly used in photodynamic therapy. Introducing the imidazole ring into the BODIPY-meso position preserves the active site and coordination orbital of the imidazole ring while enhancing the ligand's light absorption and photoresponsiveness. Using photosensitive imidazole compounds as ligands, novel photoresponsive antibacterial materials are constructed through self-assembly reactions. The efficient energy transfer between the photosensitive ligand and the metal center enhances the photoinduced antibacterial activity of the complex, leading to the development of a class of highly efficient and safe new antibacterial materials. Summary of the Invention

[0006] This invention uses photosensitive imidazole compounds as ligands to construct novel photoresponsive antibacterial materials through self-assembly reactions, thereby developing a new type of highly efficient and safe antibacterial material.

[0007] To achieve the above objectives, the technical solution adopted in this invention is as follows: first, a series of photosensitive imidazole ligands are synthesized, and then a photoactive antibacterial complex is further constructed. The chemical formula of the complex is [C]. 27 H 20 BF2N8O5M2] + The molecular structural formula is:

[0008]

[0009] Where M is Zn, Fe, Mn or Cu, and R is selected from H, -CH3, -C2H5 or -C3H7.

[0010] This invention first synthesizes imidazole ligands containing photosensitive groups, then coordinates them with metals. The synthesized visible-light-responsive antibacterial complex absorbs light in the visible light region of 350-723 nm, exhibiting good light absorption and further enhancing antibacterial activity. The synthetic route is as follows:

[0011]

[0012] The specific preparation steps are as follows:

[0013] (1) Under a nitrogen atmosphere, p-nitrobenzaldehyde and compound A are reacted with boron trifluoride diethyl ether in a first solvent in the presence of a first base for a period of time at room temperature to obtain intermediate I. The structural formula of intermediate I is:

[0014]

[0015] The structural formula of compound A is as follows: R is selected from H, -CH3, -C2H5 or -C3H7;

[0016] (2) The intermediate I obtained in step (1) was reacted with imidazole-2-carboxaldehyde in a second solvent under piperidine catalysis by heating and stirring to obtain intermediate II. The structural formula of intermediate II is:

[0017]

[0018] (3) The intermediates II and M(NO3)2 obtained in step (2) are heated in methanol, cooled, filtered, and washed. The resulting solid product is the visible light responsive antibacterial complex. The structural formula of the complex is:

[0019] Where M is Zn, Fe, Mn or Cu.

[0020] In step (1),

[0021] The first base is selected from one or more of triethylamine, sodium hydroxide, potassium hydroxide, ethylenediamine, and sodium carbonate;

[0022] The first solvent is selected from one or more of dichloromethane, ethylene glycol, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide;

[0023] The molar ratio of p-nitrobenzaldehyde, compound A, and boron trifluoride diethyl ether is (1-3):(2-4):(1-3);

[0024] The molar ratio of the first base to boron trifluoride diethyl ether is (1-2):(1-3);

[0025] The reaction time at room temperature is 8-12 hours.

[0026] Further, in step (1), the first base is triethylamine, the first solvent is dichloromethane; the molar ratio of p-nitrobenzaldehyde, compound A and boron trifluoride ether is 1:2:2; the molar ratio of the first base and boron trifluoride ether is 1:1; and the reaction time at room temperature is 12 hours.

[0027] In step (2),

[0028] The second solvent is selected from one or more of dichloromethane, ethylene glycol, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, or dimethyl sulfoxide;

[0029] The molar ratio of intermediate I to imidazole-2-carboxaldehyde is (1-3):(2-4);

[0030] The temperature for heating and stirring the reaction is 100-150℃, and the reaction time is 5-8 hours.

[0031] Further, in step (2), the second solvent is toluene, the molar ratio of intermediate I to imidazole-2-carboxaldehyde is 1:4, the heating and stirring temperature is 140℃, and the reaction time is 5h.

[0032] In step (3), the molar ratio of intermediate II and zinc nitrate hexahydrate is 1:(1-5), the heating temperature is 65℃, and the heating time is 2-6h.

[0033] Furthermore, in step (3), the molar ratio of intermediate II and zinc nitrate hexahydrate is 1:2, the heating temperature is 65℃, and the heating time is 6h.

[0034] The visible light responsive antibacterial complex described in this invention is used as a photoresponsive antibacterial material in antibacterial applications.

[0035] Furthermore, the visible light responsive antimicrobial complex described in this invention can be used to inhibit Gram-positive or Gram-negative bacteria.

[0036] The beneficial effects of this invention are as follows:

[0037] The imidazole ligands prepared in this invention exhibit strong absorption in visible light, and the complexes they form have low cytotoxicity and broad-spectrum bactericidal properties under light irradiation. They also have good antibacterial effects against both Gram-positive and Gram-negative bacteria under sunlight irradiation. Attached Figure Description

[0038] Figure 1 The NMR spectrum of the sample from step (1);

[0039] Figure 2 Figure a shows the structural formula of the complex, and Figure b shows the mass spectrum of the sample from step (2).

[0040] Figure 3 The bacterial growth curves after co-incubation of the complex from Example 2 with Staphylococcus aureus are shown.

[0041] Figure 4 The bacterial growth curve is shown after co-incubation of the complex in Example 2 with Escherichia coli. Detailed Implementation

[0042] Example 1

[0043] (1) Under a nitrogen atmosphere, 302 mg (2 mmol) of p-nitrobenzaldehyde was weighed into 25 mL of dichloromethane, and 10 μL (4 mmol) of compound A (where R is a hydrogen atom) was added. The mixture was stirred thoroughly at room temperature for 12 hours to obtain a mixture. 5 mL (4 mmol) of triethylamine was added to the mixture, and the reaction time was 30 minutes. 5 mL (4 mmol) of boron trifluoride ether was added, and the reaction was carried out for 12 hours. The reaction solution obtained in step (2) was washed with saturated brine, extracted three times with dichloromethane, and the organic phase was collected. The organic phase was dried with anhydrous sodium sulfate and concentrated under reduced pressure. The obtained organic phase was separated by silica gel column chromatography, and the orange liquid was collected. After concentration under reduced pressure, intermediate I 206.6 mg was obtained, with a yield of 28%. The NMR spectrum is shown in [reference needed]. Figure 1 , 1 H NMR (400MHz, CDCl3) δ8.40-8.35 (m, 2H), 7.53 (d, J = 8.7Hz, 2H), 6.01 (s, 2H), 2.56 (s, 6H), 1.36 (s, 6H).

[0044] The conditions for silica gel column chromatography separation were as follows: the eluent volume ratio of petroleum ether to ethyl acetate was 5:1 to elute the product.

[0045] (2) Dissolve 369 mg (1 mmol) of intermediate I obtained in step (1) in 50 mL of toluene, add 384 mg (4 mmol) of imidazole-2-formaldehyde and 2 mL of piperidine, heat at 140 °C for 5 hours. The reaction solution turns blue. After the reaction is complete, concentrate under reduced pressure to remove toluene, wash with saturated brine, extract three times with dichloromethane, collect the organic phase, dry with anhydrous sodium sulfate, and concentrate the organic phase under reduced pressure. Separate and purify the obtained organic phase by silica gel column chromatography, collect the blue liquid, concentrate under reduced pressure to obtain the blue solid, which is 341.3 mg of intermediate II, with a yield of 65%. See the mass spectrum below. Figure 2 b, 1H NMR (400MHz, DMSO) δ12.72(s,2H),8.46(d,J=8.7Hz,2H),7.87(d,J=8.6Hz,2H),7.75(d,J=16.2Hz,2H),7.38-7.20(m,6H),7.02(s,2H),1.46(s,6H).

[0046] The photosensitizer was purified by elution on a silica gel column using an eluent of ethyl acetate: petroleum ether: methanol = 3:2:1.

[0047] (3) Dissolve 52.5 mg (0.1 mmol) of the intermediate II obtained above in 8 mL of methanol, add 59.5 mg (0.2 mmol) of the metal salt (zinc nitrate hexahydrate), heat under reflux for 6 hours, and after the reaction is complete, wash three times by centrifugation with methanol to obtain the complex of formula (II), as follows. Figure 2 As shown in a. (As indicated by...) Figure 2 As shown in b, the mass spectrometry data of the complex were obtained as follows: ESI-MS (ESI + ,CH3CN):[C 27 H 20 BF2N8O5Zn2] + Theoretical value: 717.02, measured value: 717.28.

[0048] Example 2 Bacterial Growth Curve Test Experiment

[0049] The growth curves of the complex and bacteria co-incubated were determined using photoelectric turbidimetry. 1×10⁻⁶ samples were used. 9 100 μL of bacterial culture with CFU / mL was prepared and divided into light-controlled and non-light-controlled groups. The cultures were incubated in a 37℃ shaking incubator, and the UV absorbance at 600 nm was measured every 2 hours. The OD values ​​were plotted on the x-axis as incubation time. 600 A bacterial growth curve was plotted with absorbance as the ordinate. For example... Figure 3 and Figure 4 As shown, the OD value of the bacteria in the control group increased over time. The bacteria treated with the complex were completely different from those that were not treated with light after illumination. The absorbance of the light-treated cells remained relatively stable, without increase or secondary growth. The results also indicated that the complex inhibited the activity of Staphylococcus aureus and Escherichia coli during the logarithmic growth phase, preventing them from growing and dividing normally or reaching their normal logarithmic peak. Afterward, cell growth rapidly ceased, demonstrating the complex's superior antibacterial ability.

Claims

1. A visible light-responsive antibacterial complex, characterized in that, The structural formula is: ； Where M is Zn and R is selected from H.

2. The method for preparing a visible light-responsive antibacterial complex as described in claim 1, characterized in that, The steps are as follows: (1) Under a nitrogen atmosphere, p-nitrobenzaldehyde and compound A are reacted with boron trifluoride diethyl ether in a first solvent in the presence of a first base for a period of time at room temperature to obtain intermediate I. The structural formula of intermediate I is: ； The structural formula of compound A is as follows: R is selected from H; (2) The intermediate I obtained in step (1) was reacted with imidazole-2-carboxaldehyde in a second solvent under piperidine catalysis and heated and stirred to obtain intermediate II. The structural formula of intermediate II is: ； (3) The intermediates II and M(NO3)2 obtained in step (2) are heated in methanol, cooled, filtered, and washed. The resulting solid product is the visible light responsive antibacterial complex. The structural formula of the complex is: , where M is Zn.

3. The preparation method according to claim 2, characterized in that, In step (1), The first base is selected from one or more of triethylamine, sodium hydroxide, potassium hydroxide, ethylenediamine, and sodium carbonate; The first solvent is selected from one or more of dichloromethane, ethylene glycol, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide; The molar ratio of p-nitrobenzaldehyde, compound A, and boron trifluoride diethyl ether is (1-3):(2-4):(1-3); The molar ratio of the first base to boron trifluoride diethyl ether is (1-2):(1-3); The reaction time at room temperature is 8-12 hours.

4. The preparation method according to claim 3, characterized in that, In step (1), The first base is triethylamine, and the first solvent is dichloromethane; The molar ratio of p-nitrobenzaldehyde, compound A, and boron trifluoride diethyl ether is 1:2:2; The molar ratio of the first base to boron trifluoride diethyl ether is 1:1; The reaction time at room temperature was 12 hours.

5. The preparation method according to claim 2, characterized in that, In step (2), The second solvent is selected from one or more of dichloromethane, ethylene glycol, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, or dimethyl sulfoxide; The molar ratio of intermediate I to imidazole-2-carboxaldehyde is (1-3):(2-4); The temperature for heating and stirring the reaction is 100~150℃, and the reaction time is 5-8 h.

6. The preparation method according to claim 5, characterized in that, In step (2), The second solvent is toluene, and the molar ratio of intermediate I to imidazole-2-carboxaldehyde is 1:

4. The temperature for heating and stirring the reaction was 140℃, and the reaction time was 5 hours.

7. The preparation method according to claim 2, characterized in that, In step (3), the molar ratio of intermediate II to M(NO3)2 is 1:(1-5), the heating temperature is 65℃, and the heating time is 2-6h.

8. The preparation method according to claim 7, characterized in that, In step (3), the molar ratio of intermediate II to M(NO3)2 is 1:2, the heating temperature is 65℃, and the heating time is 6h.

9. The application of the visible light responsive antibacterial complex according to claim 1 in the preparation of light responsive antibacterial materials.

10. The application as described in claim 9, characterized in that, The visible light responsive antibacterial complex is used in the preparation of materials that inhibit Gram-positive or Gram-negative bacteria.

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