Preparation method of CuII-containing coordination polymer and research on inhibition effect of CuII-containing coordination polymer on soil urease and nitrifying bacteria

Abstract

The invention discloses a preparation method of a coordination polymer containing CuII and research on the inhibition effect of the coordination polymer on soil urease and nitrifying bacteria, and relates to the technical field of fertilizer.The preparation method comprises the steps that 3-aminopyridine and fumaric acid serve as raw materials to synthesize N1, N4-bis (3-pyridyl)-2-butenamide, then CuCl2. 2H2O and the synthesized N1, N4-bis (3-pyridyl)-2-butenamide are used for preparing the coordination polymer containing CuII. The novel coordination polymer [Cu (3-bbpa) (5-HIPA). H2O] is synthesized from N, N, N, N ', N'-bis (3-pyridyl)-2-butenamide and 5-hydroxyisophthalic acid by a hydrothermal method, and the crystal structure of the novel coordination polymer [Cu (3-bbpa) (5-HIPA). H2O] is analyzed to research the influence of the novel coordination polymer as an inhibitor on soil urease and nitrifying bacteria. The difunctional inhibitor is studied to delay the conversion process of urea from urea nitrogen to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen, overcomes the defect of single inhibition capability of a traditional inhibitor, is strong in inhibition capability, low in toxicity, low in cost and simple in synthesis method, can effectively improve the utilization rate and stability of the fertilizer urea, and has a wide application prospect. Nitrogen loss in agricultural activities is reduced, the fertilization cost is reduced, and the grain yield is increased.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, specifically to a fertilizer containing Cu. Ⅱ Preparation method of coordination polymer and its inhibitory effect on soil urease and nitrifying bacteria. Background Technology

[0002] Coordination polymers (CPs) are periodic network structures formed by the self-assembly of metal ions and organic ligands through coordination bonds. They possess characteristics such as structural designability, high specific surface area, tunable pore structure, and good chemical stability. In recent years, the applications of coordination polymers in catalysis, gas storage, and drug delivery have been widely explored, and their potential value in agricultural chemistry has also gradually attracted attention. In particular, coordination polymers based on specific functional metal centers can achieve selective inhibition of biological enzymes through precise design of structure and active sites, providing new ideas for the development of novel and efficient fertilizer additives. Copper ions, as transition metal centers, exhibit unique advantages in the inhibition of biological enzymes. On the one hand, copper ions have a strong affinity for electron-rich groups containing sulfur and nitrogen, and can form stable coordination with key amino acid residues (such as cysteine ​​and histidine) in the active center of urease, thereby competitively blocking substrate binding. On the other hand, copper ions can mimic the coordination environment of the natural nickel cluster in urease, interfering with the enzyme's catalytic cycle through steric hindrance and electronic effects. Meanwhile, copper ions significantly inhibit the metabolic activity of ammonia-oxidizing microorganisms, simultaneously suppressing nitrification through pathways such as interfering with cell membrane integrity, disrupting enzyme cofactors, or generating reactive oxygen species. This dual inhibitory effect on urease and nitrifying bacteria gives copper-based materials the potential to become "one-stop" nitrogen regulators. While traditional copper salt inhibitors have some effect, they suffer from problems such as easy leaching, toxic residues, and short duration of action. Copper-based coordination polymers, on the other hand, can achieve controlled release through ligand design, enhance targeting through structural regulation, and extend the field duration of action through improved stability. Furthermore, their well-defined crystal structure facilitates the optimization of inhibitory activity through molecular docking simulations, providing a theoretical basis for the rational design of highly effective inhibitors.

[0003] Therefore, developing copper-based coordination polymers with specific topological structures and functional sites is not only expected to break through the bottleneck of the single-function limitation of existing inhibitors, but also to provide an innovative material basis for achieving efficient nitrogen fertilizer utilization and green and sustainable agricultural development. Summary of the Invention

[0004] To solve the above technical problems, a Cu-containing... Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria were studied. This technical solution solves the above-mentioned problems.

[0005] One of the objectives of this invention is to synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1 N 4 -Bis(3-pyridyl)-2-butenamide was used to prepare a coordination polymer.

[0006] The second objective of this invention is to construct Cu-containing structures via a hydrothermal method. Ⅱ Coordination polymers can delay the conversion of urea nitrogen to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen after urea application, reduce the volatilization of NH3 after urea application, and the subsequent volatilization of N2O, which causes a series of problems including environmental and economic issues, reduce nitrogen loss from urea, and improve the utilization rate of urea in the soil.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A Cu-containing Ⅱ The preparation method of the coordination polymer and its inhibitory effect on soil urease and nitrifying bacteria were studied, including the following steps:

[0009] S1. Synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1 N 4 -Bis(3-pyridyl)-2-butenamide;

[0010] S2, N 1 N 4 The coordination polymer [Cu(3-bbpa)(5-HIPA)·H2O] was synthesized from bis(3-pyridyl)-2-butenamide, CuCl2·2H2O, and 5-hydroxyisophthalic acid using a hydrothermal method, yielding light blue fine crystals.

[0011] Preferably, step S1 specifically includes:

[0012] The molar ratio of 3-aminopyridine and transbutenedioic acid in the synthesis of the ligand N1,N4-bis(3-pyridyl)-2-butenamide is 2:1.

[0013] Preferably, step S2 specifically includes:

[0014] S201, 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N 1 N 4 - Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor;

[0015] S202. Add 4 ml (0.1 mol) of sodium hydroxide solution to the hydrothermal reactor, and then add 8 ml of distilled water to the hydrothermal reactor.

[0016] S203. The hydrothermal reactor was placed in an oven at 130°C and fired for 4 days to obtain light blue fine crystals. The crystals were then washed with distilled water, filtered and dried to obtain the target product.

[0017] S204. The structure of the blue bulk crystal was determined by X-ray single-crystal diffraction experiment. Its crystal type belongs to the monoclinic system and the space group is P21 / c.

[0018] Furthermore, step S2 also includes:

[0019] The molar ratio of CuCl2·2H2O to N1,N4-bis(3-pyridyl)-2-butenamide and 5-hydroxyisophthalic acid is 2:1:1.5.

[0020] Preferably, the Cu Ⅱ Coordination polymers, as a fertilizer additive, can be used in urea fertilizer. They have a good ability to inhibit the activity of soil urease and nitrifying bacteria, and delay the conversion of urea to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen in the soil. This allows nitrogen to remain in the soil for a longer period of time in the form of readily available nitrogen that is easily absorbed by crops. The inhibitory ability of these polymers on soil urease and nitrifying bacteria can be determined by measuring the absorbance of a UV spectrophotometer using methods for measuring soil urease activity and soil nitrification potential.

[0021] Preferably, the fertilizer is urea.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. By simultaneously inhibiting soil urease activity and nitrification, dual regulation of the urea conversion pathway is achieved. On the one hand, it slows down urea hydrolysis, reduces the rapid accumulation of ammonium nitrogen, and lowers ammonia volatilization losses; on the other hand, it inhibits the conversion of ammonium nitrogen to nitrate nitrogen, reducing nitrate leaching and nitrous oxide emissions. The synergistic effect of these two mechanisms allows nitrogen to remain in the soil for a longer period in a form more easily absorbed by plants, significantly improving nitrogen fertilizer utilization.

[0024] 2. Compared with traditional single inhibitors, this bifunctional inhibitor maintains long-term activity in the soil through its stable chemical structure and controllable release characteristics. Its inhibitory effect can sustainably cover the critical nitrogen-demanding period of crops, achieving a dynamic match between nitrogen supply and crop absorption, avoiding frequent topdressing, and reducing labor and material costs. By reducing ammonia volatilization and nitrous oxide emissions, it effectively mitigates air pollution and the greenhouse effect; by inhibiting nitrate leaching, it reduces the risk of groundwater pollution. Attached Figure Description

[0025] Figure 1 For ligand N 1 N 4Equation for the preparation of bis(3-pyridyl)-2-butenamide;

[0026] Figure 2 A single-cell diagram of the target product crystal prepared in Example 3;

[0027] Figure 3 The infrared absorption spectrum of the target product prepared in Example 3;

[0028] Figure 4 Comparison of the powder X-ray diffraction pattern of the target product obtained in Example 3 with the simulation diagram of single crystal data;

[0029] Figure 5 The determination of urease activity inhibition of the coordination polymer in the hydroponic experiment of Example 4;

[0030] Figure 6 The effect of the coordination polymer on urease activity inhibition in the soil culture experiment of Example 5;

[0031] Figure 7 The effect of the coordination polymer on inhibiting nitration activity in the soil culture experiment in Example 5;

[0032] Figure 8 The crystallographic parameters of the target product obtained in Example 3 are shown. Detailed Implementation

[0033] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0034] Reference Figure 1-8 As shown, a Cu-containing Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria were studied. The preparation method includes the following steps:

[0035] S1. Synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1 N 4 -Bis(3-pyridyl)-2-butenamide;

[0036] S2, N 1 N 4 The coordination polymer [Cu(3-bbpa)(5-HIPA)·H2O] was synthesized from bis(3-pyridyl)-2-butenamide, CuCl2·2H2O, and 5-hydroxyisophthalic acid using a hydrothermal method, yielding light blue fine crystals.

[0037] Reference Figure 1 As shown, ligand N 1 N 4The preparation method of bis(3-pyridyl)-2-butenamide is as follows: 3-aminopyridine (9.41 g, 0.10 mol) dissolved in 35 mL of pyridine solution was slowly transferred to 20 mL of pyridine solution containing fumaric acid (5.80 g, 0.05 mol). After stirring at room temperature for 30 min, triphenyl phosphite (15.5 g, 0.05 mol) was added dropwise over 15 min. The mixture was heated under reflux for 10 h and left to stand overnight at room temperature. The solid precipitated, filtered, recrystallized with ethanol, and dried in air to obtain a powdered solid with a yield of 64%.

[0038] Cu Ⅱ The preparation method of the coordination polymer is as follows: 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N2O are added. 1 N 4 Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor. 4 ml (0.1 mol) of sodium hydroxide solution was added to the reactor, followed by 8 ml of distilled water. The reactor was then placed in an oven at 130 °C for 4 days to obtain light blue fine crystals. These crystals were then washed repeatedly with distilled water, filtered, and dried to obtain more light blue crystals.

[0039] Example 1: A Cu-containing Ⅱ Preparation of coordination polymers

[0040] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N 1 N 4 Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor. 4 ml (0.1 mol) of sodium hydroxide solution was added to the reactor, followed by 8 ml of distilled water. The reactor was then placed in an oven at 130 °C for 4 days to obtain fine blue crystals. These crystals were then washed repeatedly with distilled water, filtered, and dried to obtain light blue crystals. The yield was approximately 52%.

[0041] Example 2 A Cu-containing Ⅱ Preparation of coordination polymers

[0042] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N 1 N 4Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor. 4 ml (0.1 mol) of sodium hydroxide solution was added to the reactor, followed by 8 ml of distilled water. The reactor was then placed in an oven at 130 °C for 4 days to obtain light blue fine crystals. These crystals were then washed repeatedly with distilled water, filtered, and dried to obtain light blue crystals. The yield was approximately 53%.

[0043] Example 3 A Cu-containing Ⅱ Preparation of coordination polymers

[0044] 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N 1 N 4 Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor. 4 ml (0.1 mol) of sodium hydroxide solution was added to the reactor, followed by 8 ml of distilled water. The reactor was then placed in an oven at 130 °C for 4 days to obtain fine blue crystals. These crystals were then washed repeatedly with distilled water, filtered, and dried to obtain light blue crystals. The yield was approximately 51%.

[0045] A Cu-containing Ⅱ Determination of coordination polymer structure:

[0046] The diffraction intensity data of the single crystal were collected using graphite monochromatic Mo Kα (λ = 0.71073 Å) radiation as the diffraction source on a Bruker D8-ray diffractometer.

[0047] Cu obtained from the light blue blocky crystals prepared in Example 1 Ⅱ Data obtained from SC-XRD of secondary coordination polymers, and further structural diagrams as shown in the figure. Figure 2 (As shown). Its crystal form belongs to the monoclinic crystal system, and the space group is P21 / c. This polymer consists of a copper(II) ion, two 5-HIPA ligands, and two 3-bbpa ligands. The central copper(II) ion coordinates with two oxygen atoms from the two 5-HIPA ligands, one oxygen atom from the coordinated water, and two nitrogen atoms from the 3-bbpa ligands. Meanwhile, the Cu-N and Cu-O bond lengths are 2.011(2)-2.041(2) Å and 1.981(18)-2.376(2) Å, respectively. The copper(II) ion and the 5-HIPA ligands are alternately linked to form a one-dimensional [Cu(5-HIPA)] linear chain. Similarly, the copper(II) ion and the 3-bbpa ligands are interconnected to form a one-dimensional [Cu(3-bbpa)] chain structure.

[0048] Its crystallographic parameters are as follows Figure 8 Powder diffraction experiments were performed on the crystal using a Bruker D8 Advance X-ray powder diffractometer. Graphite monochromatic CuKα radiation was used at a wavelength of λ = 1.54056 Å, with a solid-state detector, a step size of 0.02°, a scan speed of 0.1 / s, and a scan range of 5°≤2θ≤90°.

[0049] Reference Figure 4 As shown, the powder X-ray diffraction pattern obtained in Example 3 matches the single-crystal data simulation pattern.

[0050] Example 4 Cu Ⅱ Determination of urease activity inhibition by secondary coordination polymers (hydroponic culture)

[0051] The jack bean urease used in the test was purchased from Shanghai Maclean Biotechnology Co., Ltd.

[0052] Take 4 mL (10 KU / L) and 4 mL of samples with different inhibitor concentrations (the samples were dissolved in DMSO:H2O=1:1) and mix them thoroughly. After pre-culturing at 37°C for 1 h, add 32 mL of phosphate buffer (pH=6.8, containing 500 Mm / L urea and 0.002% phenol red indicator). The pH range is 6.8-7.7. Measure the absorbance at 570 nm using a UV spectrometer at 1 h intervals.

[0053] The endpoint of the test is determined by phenol red indicator; the test is stopped when the solution changes from light orange-yellow to purple-red.

[0054] IC 50 Calculation using the modified Kohl's method: lgIC 50 =Xm-I(P-(3-Pm-Pn) / 4), where Xm:lg maximum dose, I:lg(maximum dose / adjacent dose), P: sum of positive response rates, Pm: maximum positive response rate, Pn: minimum positive response rate.

[0055] IC was calculated 50 =0.62±0.01 μM / L, indicating that when this Cu... Ⅱ Secondary coordination polymers, as urease inhibitors, have low half-inhibitory concentrations and require small amounts of additives, such as... Figure 5 As shown.

[0056] Therefore, it can be concluded that: the Cu of the present invention... Ⅱ Secondary coordination polymers can be used as urease inhibitors in fertilizer urea.

[0057] Example 5 Cu Ⅱ Determination of urease and nitration activity inhibition by secondary coordination polymers (soil culture)

[0058] 1. Verification Experiment:

[0059] Taking Example 1 as an example, a soil culture verification experiment was conducted at the Shenyang Institute of Applied Ecology, Chinese Academy of Sciences. 500g of air-dried soil (passed through a 10-mesh sieve) and corresponding amounts of nitrogen fertilizer (urea), phosphorus fertilizer (superphosphate), potassium fertilizer (potassium chloride), and coordination polymer were accurately weighed. The amounts of urea, superphosphate, and potassium chloride added were 0.1857 g / kg soil, 0.05915 g / kg soil, and 0.06345 g / kg soil, respectively. The amount of coordination polymer added was 0.8% of the fertilizer amount. The nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, and coordination polymer were thoroughly shaken until uniformly mixed. Then, the mixture was mixed with 5g of soil, then with 45g of soil, then with 150g of soil, then with 300g of soil, gradually increasing the mixture until the fertilizer and coordination polymer were fully mixed with the soil. The soil-fertilizer mixture was added to a culture container, and the weight A of the container and soil was recorded. Then, 100ml of water was evenly added to the soil surface, and the total mass B of the container, soil, and solution was recorded. The quality of the container and soil was measured before and after each soil sampling, and water was added according to the original amount when the soil moisture was insufficient. After each water addition, the container opening was sealed with Para film and placed in a 25℃ constant temperature incubator. Soil samples were taken on the 3rd, 7th, 15th and 30th days after incubation to measure soil urease and nitrification potential activities.

[0060] 2. Comparative experiment:

[0061] The experimental conditions were the same as those in the verification experiment, except that the coordination polymer from Example 1 was not added to the fertilizer.

[0062] 3. Results

[0063] The urease activity in the experimental soil was significantly lower than that in the control soil on days 3, 7, and 15, with reductions of 3.23%, 4.45%, and 2.17%, respectively. This indicates that the coordination polymer has an inhibitory effect on urease activity. Figure 6 As shown.

[0064] Meanwhile, the nitrification potential activity in the experimental soil was significantly lower than that in the control soil on days 7, 15, and 30, with decreases of 17.53%, 12.34%, and 5.36%, respectively. Figure 7 As shown, this demonstrates that the coordination polymer has a dual-control effect of simultaneously inhibiting urease activity and nitration activity.

[0065] In summary, the advantages of this invention are as follows: by simultaneously inhibiting soil urease activity and nitrification, it achieves dual regulation of the urea conversion pathway. On the one hand, it delays urea hydrolysis, reduces the rapid accumulation of ammonium nitrogen, and lowers ammonia volatilization losses; on the other hand, it inhibits the conversion of ammonium nitrogen to nitrate nitrogen, reducing nitrate leaching and nitrous oxide emissions. The synergistic effect of these two mechanisms allows nitrogen to remain in the soil for a longer period in a form more easily absorbed by plants, significantly improving nitrogen fertilizer utilization. Compared with traditional single inhibitors, this bifunctional inhibitor maintains long-term activity in the soil through its stable chemical structure and controllable release characteristics. Its inhibitory effect can sustainably cover the critical nitrogen requirement period of crops, achieving a dynamic match between nitrogen supply and crop absorption, avoiding frequent topdressing, and reducing labor and material costs. By reducing ammonia volatilization and nitrous oxide emissions, it effectively alleviates air pollution and the greenhouse effect; by inhibiting nitrate leaching, it reduces the risk of groundwater pollution.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A Cu-containing Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, The preparation method includes the following steps: S1. Synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1 N 4 -Bis(3-pyridyl)-2-butenamide; S2, N 1 N 4 The coordination polymer [Cu(3-bbpa)(5-HIPA)·H2O] was synthesized from bis(3-pyridyl)-2-butenamide, CuCl2·2H2O, and 5-hydroxyisophthalic acid using a hydrothermal method, yielding light blue fine crystals.

2. A Cu-containing compound according to claim 1 Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, Step S1 specifically includes: The molar ratio of 3-aminopyridine and transbutenedioic acid in the synthesis of the ligand N1,N4-bis(3-pyridyl)-2-butenamide is 2:

1.

3. A Cu-containing compound according to claim 2 Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, Step S2 specifically includes: S201, 0.034 g (0.2 mmol) of CuCl2·2H2O and 0.027 g (0.1 mmol) of N 1 N 4 - Bis(3-pyridyl)-2-butenamide and 0.027 g (0.15 mmol) of 5-hydroxyisophthalic acid were placed in a hydrothermal reactor; S202. Add 4 ml (0.1 mol) of sodium hydroxide solution to the hydrothermal reactor, and then add 8 ml of distilled water to the hydrothermal reactor. S203. The hydrothermal reactor was placed in an oven at 130°C and fired for 4 days to obtain light blue fine crystals. The crystals were then washed with distilled water, filtered and dried to obtain the target product. S204. The structure of the blue bulk crystal was determined by X-ray single-crystal diffraction experiment. Its crystal type belongs to the monoclinic system and the space group is P21 / c.

4. A Cu-containing compound according to claim 3 Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, Step S2 further includes: The molar ratio of CuCl2·2H2O to N1,N4-bis(3-pyridyl)-2-butenamide and 5-hydroxyisophthalic acid is 2:1:1.

5.

5. A Cu-containing compound according to claim 4 Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, include: The Cu Ⅱ Coordination polymers, as a fertilizer additive, can be used in urea fertilizer. They have a good ability to inhibit the activity of soil urease and nitrifying bacteria, and delay the conversion of urea to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen in the soil. This allows nitrogen to remain in the soil for a longer period of time in the form of readily available nitrogen that is easily absorbed by crops. The inhibitory ability of these polymers on soil urease and nitrifying bacteria can be determined by measuring the absorbance of a UV spectrophotometer using methods for measuring soil urease activity and soil nitrification potential.

6. A Cu-containing compound according to claim 5 Ⅱ The preparation method of coordination polymers and their inhibitory effects on soil urease and nitrifying bacteria are characterized by, include: The fertilizer is urea.

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