CN107043354B

CN107043354B - 2-benzimidazolyl copper benzoate complex with antifungal activity and preparation method thereof

Info

Publication number: CN107043354B
Application number: CN201710411497.XA
Authority: CN
Inventors: 王大伟; 杨斌; 赵宁; 杨思林; 泽桑梓; 史正军; 吴晓丽; 冯小飞
Original assignee: Southwest Forestry University
Current assignee: Southwest Forestry University
Priority date: 2017-06-05
Filing date: 2017-06-05
Publication date: 2020-03-24
Anticipated expiration: 2037-06-05
Also published as: CN107043354A

Abstract

The invention discloses a 2-benzimidazolyl copper benzoate complex with antifungal activity and a preparation method. The complex is prepared by reacting 2-benzimidazolyl benzoic acid with Cu(NO ₃ ) ₂ •3H ₂ O in a mixed solvent of ethanol and water, and the heating temperature is controlled at 100° C. for 48 hours. The molecular structure of the copper complex was confirmed by X-ray single crystal diffraction and infrared spectroscopy. The antifungal activity experiments showed that the copper complexes had good inhibitory activity against the fungi wheat total erosion and rice blight. The molecular structure of the copper complex is as follows:

.

Description

2-benzimidazolyl copper benzoate complex with antifungal activity and preparation method thereof

Technical Field

The invention belongs to an antibacterial agent for crops, and particularly relates to a metal complex of a benzimidazole heterocyclic compound and a preparation method thereof.

Technical Field

The benzimidazole heterocyclic compound has various biological activities such as antifungal activity, antibacterial activity, anticancer activity, nerve activity and the like, has important value in the field of medicinal chemistry and also has important position in the aspect of pesticide development and research, and the high-efficiency and low-toxicity benzimidazole bactericide carbendazim is one of the most widely applied broad-spectrum antifungal agents at present. The synthesis method of the compound mainly comprises two methods. One is prepared by reacting o-phenylenediamine with a carboxylic acid under acidic conditions, which generally requires high temperature and high pressure conditions and long reaction times. The other method is prepared by reacting o-phenylenediamine with aldehyde, and the method needs relatively mild reaction conditions and short reaction time, but easily generates a large amount of Schiff base byproducts in the condensation process of amino and aldehyde groups. It is therefore important to control reasonable reaction conditions to reduce the yield of the Schiff base.

In addition, the organic copper compound has good antibacterial effect, and thus becomes a hot spot for research on antifungal drugs at present. Divalent copper ion (Cu)²⁺) The Bordeaux mixture has strong antibacterial activity, is the copper ion bactericide developed at the earliest time, has the advantages of low cost, good antibacterial effect and low toxicity, and is widely used for killing various plant pathogenic bacteria until now. Currently, the broad-spectrum organic copper antibacterial agent thiabendazole copper is sold in the market. In recent years, a complex compound synthesized by a coordination reaction between a metal ion and an organic molecule has been demonstrated to have an important application value in terms of antibacterial activity. Research shows that the antibacterial activity of the metal-organic coordination compound is obviously superior to that of the used metal ions and organic ligands thereof.

Disclosure of Invention

The invention aims to provide a novel organic copper antifungal agent, namely a 2-benzimidazolyl copper benzoate complex with antifungal activity, and a method for synthesizing the organic copper antifungal agent by using 2-benzimidazolyl benzoic acid and copper nitrate as raw materials.

The invention is realized by the following technical scheme:

provides a 2-benzimidazolyl copper benzoate complex with antifungal activity, and the molecular formula of the complex is C₂₈H₁₈N₄O₄Cu, structure as follows:

the invention provides a method for preparing the 2-benzimidazolyl copper benzoate complex with antifungal activity, which comprises the following steps:

adding Cu (NO) into a 50 mL polytetrafluoroethylene reaction kettle₃)₂•3H₂O and 2-benzimidazole benzoic acid, wherein the molar ratio of the two is 1: 1; then adding volume ratio V_Ethanol: V_{Water (W)}20 mL of a mixed solvent of absolute ethanol and water in a ratio of 1:1, and stirring the mixture at room temperature for 15 min; sealing the reaction kettle, and reacting at 100 ℃ for 48 hours to obtain the product.

Further, the preparation method of the 2-benzimidazole benzoic acid comprises the following steps: firstly, adding o-phenylenediamine into a round-bottom flask, dissolving the o-phenylenediamine in 15 ml of absolute ethyl alcohol, and dropwise adding an absolute ethyl alcohol solution of 2-formylbenzoic acid under stirring, wherein the molar ratio of the o-phenylenediamine to the 2-formylbenzoic acid is 1: 1; after the 2-formylbenzoic acid is added, continuously reacting for 6 hours at the temperature of 60-100 ℃; and (3) carrying out vacuum filtration and washing with ethanol to obtain a white powdery solid with a yield of 80-90%.

The technical scheme of the invention also comprises: a method for applying the 2-benzimidazolyl copper benzoate complex with antifungal activity.

The following copper 2-benzimidazolyl benzoate complexes were also used with Cu (2-biba)₂And (4) showing.

Synthesis of [ Cu (2-biba)₂]The reaction formula (c) is as follows:

the invention [ Cu (2-biba)₂]The molecular structure of (A) was confirmed by X-ray single crystal diffraction and infrared spectroscopy.

The present invention fully considers the divalent copper ion (Cu)²⁺) And benzimidazole derivatives in antifungal activity, preparing a novel organic copper antibacterial agent with antifungal activity through coordination reaction, and preparing a copper complex [ Cu (2-biba)₂]Has the beneficial effect of antifungal activity.

The yield of the method for preparing 2-benzimidazolylbenzoic acid provided by the invention reaches 80-90%, and a convenient raw material is provided for preparing the 2-benzimidazolylbenzoic acid copper complex.

For the copper complex [ Cu (2-biba) prepared by the invention₂]The test of inhibiting fungi by PDA culture medium is carried out, and the test result shows that: copper complex [ Cu (2-biba)₂]Has obvious inhibiting effect on both wheat take-all and rice blight fungi, and the bacteriostasis rates reach 86 percent and 89 percent respectively when the medicine-containing concentration is 50 mg/L.

Drawings

FIG. 1 is a copper complex [ Cu (2-biba)₂]A crystal photograph of (a).

FIG. 2 is a copper complex [ Cu (2-biba)₂]The molecular structure diagram of (1), which is obtained from X-ray single crystal diffraction data.

FIG. 3 is a copper complex [ Cu (2-biba)₂]An infrared spectrum of (1).

The present invention is further illustrated below with reference to specific embodiments, which include but do not limit the scope of the invention.

Detailed Description

2-benzimidazolylbenzoic acid (2-biba) copper complex [ Cu (2-biba)₂]The synthesis of (2):

example 1:

0.24 g Cu (NO) was added to a 50 mL Teflon reactor₃)₂•3H₂O (1 mmol) and 0.24 g 2-benzimidazolylbenzoic acid (1 mmol), adding 20 mL absolute ethyl alcohol as solvent, stirring at room temperature for 15 min to mix the reactants uniformly, sealing the reaction kettleThen reacted at 100 ℃ for 48 h. A reddish brown crystalline solid was formed in 38% yield.

Example 2:

0.24 g Cu (NO) was added to a 50 mL Teflon reactor₃)₂•3H₂O (1 mmol) and 0.24 g of 2-benzimidazolylbenzoic acid (1 mmol), and 20 mL of a mixed solvent of anhydrous ethanol and water (V) was added_Ethanol: V_{Water (W)}= 1: 1), stirring for 15 min at room temperature to uniformly mix reactants, sealing the reaction kettle, and reacting for 48 h at 100 ℃. A reddish brown crystalline solid was formed in 68% yield.

Experiments as a comparison;

example 3:

0.24 g Cu (NO) was added to a 50 mL Teflon reactor₃)₂•3H₂O (1 mmol) and 0.24 g 2-benzimidazolylbenzoic acid (1 mmol), then adding 20 mL distilled water as a solvent, stirring at room temperature for 15 min to uniformly mix the reactants, sealing the reaction kettle, and reacting at 100 ℃ for 48 h. 2-benzimidazole benzoic acid is difficult to dissolve in water and cannot be mixed with Cu²⁺No target product is produced.

Example 4:

0.24 g Cu (NO) was added to a 50 mL Teflon reactor₃)₂•3H₂O (1 mmol) and 0.24 g of 2-benzimidazolylbenzoic acid (1 mmol), and 20 mL of a mixed solvent of anhydrous ethanol and water (V) was added_Ethanol: V_{Water (W)}= 1: 1), stirring for 15 min at room temperature to uniformly mix reactants, sealing the reaction kettle, and reacting for 48 h at 120 ℃. A large amount of black precipitates are formed at the bottom of the reaction kettle, and no target product is generated.

As can be seen from the above examples, in the preparation of copper complex [ Cu (2-biba)₂]In the reaction of (3), the formation of the copper complex is facilitated by controlling the temperature to 100 ℃, and when the temperature is too high, the oxidation reaction occurs and no target product is formed. In addition, when a mixed solvent of absolute ethanol and water in a volume ratio of 1:1 is used, the maximum yield of the objective product can be obtained.

The copper complex of the present invention [ Cu (2-biba)₂]The chemical properties of the (A) are stable,is not easy to be oxidized and deteriorated, has low solubility in water, and can be dissolved in common organic solvents such as N, N-dimethylformamide, dimethyl sulfoxide and the like.

Secondly, the synthesis of the ligand 2-benzimidazole benzoic acid (2-biba) of the invention

The invention provides a novel method for preparing 2-benzimidazolylbenzoic acid (2-biba) ligand, which comprises the following key steps: by controlling the reaction temperature and the reaction time, the yield of the 2-benzimidazole benzoic acid is improved, and the yield of the byproduct Schiff base is reduced.

Example 1:

1.08 g of o-phenylenediamine (10 mmol) was added to a 100 mL round-bottomed flask, dissolved in 20 mL of anhydrous ethanol, and a solution (20 mL) of 1.5 g of 2-formylbenzoic acid (10 mmol) in anhydrous ethanol was added dropwise with stirring at 60 ℃; after the addition is finished, stirring and reacting for 3 hours at 60 ℃; the mixture is filtered by a cloth-type funnel under reduced pressure, and the obtained solid powder is washed for 3 times by 15 mL of absolute ethyl alcohol to obtain a white powdery product with the yield of 80 percent.

Example 2:

1.08 g of o-phenylenediamine (10 mmol) was added to a 100 mL round-bottomed flask, dissolved in 20 mL of anhydrous ethanol, and a solution of 1.5 g of 2-formylbenzoic acid (10 mmol) in anhydrous ethanol (20 mL) was added dropwise with stirring at 60 ℃. After the addition was complete, the reaction was continued with stirring at 60 ℃ for 6 hours. The reaction was stopped, a cloth funnel was used to pump and filter under reduced pressure, and the resulting solid powder was washed 3 times with 15 mL of absolute ethanol to give a white powder product with 90% yield.

Example 3:

1.08 g of o-phenylenediamine (10 mmol) was added to a 100 mL round-bottomed flask, dissolved in 20 mL of anhydrous ethanol, and a solution of 1.5 g of 2-formylbenzoic acid (10 mmol) in anhydrous ethanol (20 mL) was added dropwise with stirring at 100 ℃. After the addition was complete, the reaction was continued with stirring at 100 ℃ for 6 hours. Stopping the reaction, performing reduced pressure suction filtration by using a cloth type funnel, and washing by using ethanol to obtain a white solid powdery product with the yield of 90%.

Experiments as a comparison;

example 4:

1.08 g of o-phenylenediamine (10 mmol) was added to a 100 mL round-bottomed flask, dissolved in 20 mL of anhydrous ethanol, and a solution of 1.5 g of 2-formylbenzoic acid (10 mmol) in anhydrous ethanol (20 mL) was added dropwise with stirring at room temperature. After the addition was complete, the reaction was stirred at room temperature (20 ℃ C.) for 6 hours. Stopping the reaction, performing reduced pressure suction filtration by using a cloth type funnel, and washing by using ethanol to obtain a white solid powdery product with the yield of 45%.

According to the embodiment, in the reaction for preparing the 2-benzimidazole benzoic acid, the reaction temperature is controlled to be 60-100 ℃, so that the benzimidazole heterocyclic structure is favorably formed by dehydration; the low temperature is favorable for generating yellow Schiff base byproducts, so that the yield of the target product is reduced. Because the solubility of the Schiff base byproduct in ethanol is far greater than that of 2-benzimidazolylbenzoic acid in ethanol, the Schiff base byproduct can be removed after the solid product after suction filtration is washed by ethanol. The heating reaction time is prolonged, so that the target product 2-benzimidazole benzoic acid is generated.

Thirdly, the copper complex [ Cu (2-biba)₂]Inhibitory effect on fungi

Copper complexes [ Cu (2-biba) were tested by a medicated media method₂]In vitro inhibitory activity against fungal rice blight and wheat take-all. Accurately weigh 200 mg [ Cu (2-biba)₂]Dissolved in 20 mL of DMF to prepare a mother liquor with a concentration of 10 mg/mL for use. 0.2 mL and 0.5 mL of the above mother liquors were respectively sucked up by a pipette and added to a volume of 100 mL of PDA medium, when [ Cu (2-biba) is present in the medium, and mixed well₂]The concentrations of (A) were 20 mg/L and 50mg/L, respectively. Then placing the culture medium into a sterilizing pot for sterilization for 3 h, adding the culture medium into a culture dish under the aseptic condition after sterilization, and preparing a drug-containing flat plate. The cultured pathogens were aseptically picked up from the edge of the colony using a 4 mm diameter punch and inoculated into the center of a petri dish in 3 replicates for each fungus. A culture dish without the copper complex but with the same amount of DMF is used as a blank control, the diameters of colonies are measured after all the culture dishes are placed in an incubator at 28 ℃ for culturing for 48 hours, the diameter of each colony is vertically measured by a cross method, and the average value of 3 parallel experiments is taken. The formula for calculating the bacteriostasis rate is as follows:

TABLE 1 inhibitory Effect of copper complexes of different concentrations on two fungi

After the same culture time, the smaller the colony diameter is, the better the bacteriostasis effect is. The measured colony diameters of the experimental group were compared with those of the control group, and the results are shown in Table 1. The results of antifungal experiments show that the copper complex [ Cu (2-biba)₂]Has obvious inhibiting effect on both wheat take-all and rice blight fungi, and the bacteriostasis rates reach 86 percent and 89 percent respectively when the medicine-containing concentration is 50 mg/L.

Claims

1. The method for applying the 2-benzimidazolyl copper benzoate complex with antifungal activity is characterized in that: the 2-benzimidazolyl copper benzoate complex is used for preventing and treating rice plague fungi and wheat take-all fungi, and the molecular structure of the complex is as follows:

。

2. the process according to claim 1, wherein the copper 2-benzimidazolylbenzoate complex is used as a reaction product containing: for wheat holotrichia fulva with the colony diameter of 3.2cm, the bacteriostasis rate reaches 86% when the concentration of the copper complex containing 2-benzimidazolyl benzoate is 50 mg/L; for rice disease fungi with the colony diameter of 3.9cm, the bacteriostasis rate reaches 89% when the concentration of the copper complex containing 2-benzimidazolyl benzoate is 50 mg/L.