A copper-based coordination polymer, a preparation method and application thereof in nitrogen fertilizer synergism

Abstract

The application belongs to the technical field of fertilizer synergism, and particularly relates to a copper-based coordination polymer, a preparation method and application in nitrogen fertilizer synergism. 1 ,N 4 -dual (3-pyridyl)-2-buteneamide; then N 1 ,N 4 -dual (3-pyridyl)-2-buteneamide, CuCl2.2H2O and 5-nitroisophthalic acid are used to synthesize a new copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)].H2O by a hydrothermal method, which is a blue fine crystal. The copper-based coordination polymer prepared in the application can simultaneously target the urease active center and the nitrifying microbial functional unit, the three-dimensional network structure of the copper-based coordination polymer not only enhances the stability of the material in the soil, but also realizes the double blocking of the key enzymes of nitrogen transformation through the multi-site synergistic effect.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer efficiency enhancement technology, specifically relating to a copper-based coordination polymer, its preparation method, and its application in enhancing nitrogen fertilizer efficiency. 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. Novel bifunctional inhibitors based on copper-based coordination polymers are designed and applied based on the structural controllability and functional modifiability of coordination polymers. By precisely controlling the type of metal, ligand structure, and synthesis conditions, functional materials with specific geometries, electronic properties, and stability can be obtained, providing an ideal molecular platform for developing efficient and targeted agricultural inhibitors. Copper ions play a crucial role as the central metal in these inhibitors: on the one hand, copper ions have a high affinity for the thio and amino functional groups at the active site of urease, and can inhibit enzyme catalytic activity through competitive coordination; on the other hand, copper ions can interfere with the metabolic processes of ammonia-oxidizing microorganisms, achieving nitrification inhibition by disrupting cell membrane integrity or inhibiting the function of key enzymes. Compared to free copper ions, copper species immobilized in the form of coordination polymers exhibit greater stability and controllable release, significantly reducing the concentration of free copper ions in the soil and minimizing environmental risks while ensuring inhibition efficiency. Traditional inhibitors often target single processes (such as inhibiting only urease or only nitrification), making it difficult to achieve full-process regulation of nitrogen transformation.

[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 address the aforementioned technical problems, this invention provides a copper-based coordination polymer, its preparation method, and its application in enhancing nitrogen fertilizer efficiency. By integrating structural stability, metal activity, and slow-release properties, it can simultaneously and effectively inhibit urea hydrolysis and ammonium oxidation processes, forming a synergistic enhancement mechanism. While maintaining high inhibitory activity, this material possesses good soil adaptability and environmental compatibility, demonstrating clear application potential and industrial value in refined nitrogen management, reducing fertilizer loss, and mitigating agricultural non-point source pollution.

[0005] This invention is achieved by providing a method for preparing a copper-based coordination polymer, comprising the following steps:

[0006] Step 1: Synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1N 4 -Bis(3-pyridyl)-2-butenamide;

[0007] Step 2: Then add N 1 N 4 A new copper-based coordination polymer, [Cu(3-bbpa)(5-NIPA)]·H2O, was synthesized via hydrothermal method using bis(3-pyridyl)-2-butenamide, CuCl2·2H2O, and 5-nitroisophthalic acid. The polymer is a fine blue crystal.

[0008] Preferably, step 1 includes the following specific steps:

[0009] Step 101: Slowly add 3-aminopyridine dissolved in pyridine solution to pyridine solution of fumaric acid, and stir at room temperature;

[0010] Step 102: Add triphenyl phosphite dropwise to the mixed liquid obtained in step 101, heat to reflux, let stand overnight at room temperature until a solid precipitates, filter, recrystallize with ethanol, and dry in air to obtain a powdery solid, i.e., N. 1 N 4 -Bis(3-pyridyl)-2-butenamide.

[0011] Further preferred, the molar ratio of 3-aminopyridine, trans-butenedioic acid and triphenyl phosphite is 2:1:1.

[0012] Further preferred, in step 101, stirring is performed for 30 min; in step 102, triphenyl phosphite is added dropwise within 15 min after the end of step 101, and the mixture is heated under reflux for 10 h.

[0013] Preferably, step 2 includes the following specific steps:

[0014] Step 201: Mix CuCl2·2H2O and N 1 N 4 -Bis(3-pyridyl)-2-butenamide and 5-nitroisophthalic acid were placed in a hydrothermal reactor;

[0015] Step 202: Add sodium hydroxide solution to the hydrothermal reactor, and then add distilled water to the hydrothermal reactor;

[0016] Step 203: Place the hydrothermal reactor in an oven and calcine to obtain fine blue crystals. Then wash them with distilled water, filter and dry them to obtain the copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)]·H2O.

[0017] Further optimization, in step 201, CuCl2·2H2O and N 1 N 4The molar ratio of bis(3-pyridyl)-2-butenamide and 5-nitroisophthalic acid is 2:1:1.5.

[0018] Further preferred, in step 202, the concentration of the sodium hydroxide solution is 0.025 mol / mL, and the volume ratio of the sodium hydroxide solution to distilled water is 1:2; in step 203, the hydrothermal reactor is placed in an oven at 130 ℃ and fired for 4 days.

[0019] This invention also provides a copper-based coordination polymer prepared according to the above-described method, wherein the crystal form, as determined by X-ray single-crystal diffraction, belongs to the triclinic crystal system and the space group is [missing information]. P -1.

[0020] The present invention also provides an application of the copper-based coordination polymer in enhancing the efficiency of nitrogen fertilizer, specifically by adding it as a fertilizer additive to nitrogen fertilizer to inhibit the activity of soil urease and nitrifying bacteria.

[0021] Preferably, in the above applications, the nitrogen fertilizer is urea.

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

[0023] Based on the precisely designed spatial structure and active site distribution of the coordination polymer, the copper-based coordination polymer prepared in this invention can simultaneously target the urease active center and the functional units of nitrifying microorganisms. Its three-dimensional network structure not only enhances the stability of the material in soil, but also achieves dual blocking of key nitrogen conversion enzymes through multi-site synergistic effects, overcoming the technical defects of traditional single-function inhibitors that have a single target and are easily evaded by microbial metabolism. Attached Figure Description

[0024] Figure 1 This is a crystal unit cell diagram of the target product prepared in Example 1;

[0025] Figure 2 This is the infrared absorption spectrum of the target product prepared in Example 1;

[0026] Figure 3 This is a comparison between the powder X-ray diffraction pattern of the target product obtained in Example 1 and the simulated pattern based on single-crystal data;

[0027] Figure 4 This is the assay of urease activity inhibition of the coordination polymer in Example 4 (hydroponic culture).

[0028] Figure 5 This describes the urease activity inhibition effect of the coordination polymer in Example 5 (soil cultivation).

[0029] Figure 6 This is the nitration activity inhibition effect of the coordination polymer in Example 5 (soil cultivation). Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, a further detailed description is provided below in conjunction with the accompanying drawings, embodiments, and comparative experiments. It should be understood that the specific content described herein is for explanation and support only and is not intended to limit the invention.

[0031] This invention provides a copper-based coordination polymer and its preparation method, specifically including the following steps:

[0032] 1. N 1 N 4 Synthesis of bis(3-pyridyl)-2-butenamide:

[0033]

[0034] Step 101: Slowly add 3-aminopyridine dissolved in pyridine solution to pyridine solution of fumaric acid, and stir at room temperature for 30 min;

[0035] Step 102: Triphenyl phosphite was added dropwise to the mixed liquid obtained in Step 101 within 15 min. The molar ratio of 3-aminopyridine, fumaric acid, and triphenyl phosphite was 2:1:1. The mixture was heated under reflux for 10 h and left to stand overnight at room temperature until a solid precipitated. The solid was then filtered, recrystallized from ethanol, and dried in air to obtain a powdery solid, namely N. 1 N 4 -Bis(3-pyridyl)-2-butenamide.

[0036] 2. Preparation of copper-based coordination polymers:

[0037] Step 201: Mix CuCl2·2H2O and N 1 N 4 -Bis(3-pyridyl)-2-butenamide and 5-nitroisophthalic acid were placed in a hydrothermal reactor at a molar ratio of 2:1:1.5;

[0038] Step 202: Add a sodium hydroxide solution with a concentration of 0.025 mol / mL to the hydrothermal reactor, and then add distilled water to the hydrothermal reactor. The volume ratio of sodium hydroxide solution to distilled water is 1:2.

[0039] Step 203: Place the hydrothermal reactor in an oven at 130 ℃ and bake for 4 days to obtain fine blue crystals. Then wash them with distilled water, filter and dry them to obtain the copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)]·H2O.

[0040] Example 1

[0041] 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, was filtered, recrystallized from ethanol, and dried in air to obtain a powdery solid with a yield of 64%.

[0042] 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-nitroisophthalic acid were placed in a hydrothermal reactor; 4 ml (0.1 mol) of sodium hydroxide solution was added to the hydrothermal reactor, followed by 8 ml of distilled water; the hydrothermal reactor was placed in an oven at 130 °C for 4 days to obtain fine blue crystals, which were then washed repeatedly with distilled water, filtered and dried to obtain the copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)]·H2O, with a yield of approximately 55%.

[0043] Example 2

[0044] Repeat Example 1, with a yield of approximately 54%.

[0045] Example 3

[0046] Repeating Example 1, the yield was approximately 56%. Examples 1-3 demonstrate that the method has a stable yield.

[0047] Structure determination of copper-based coordination polymers:

[0048] 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 X-ray diffractometer. The copper-based coordination polymer (SC-XRD data) obtained from the blue bulk crystal prepared in Example 1 is shown in the figure below. Figure 1 (As shown). The copper-based coordination polymer obtained from the blue bulk crystals prepared in Example 1 was mixed and ground with 100-200 mg of dry KBr powder using the KBr pelleting method. The mixture was then pressed into transparent sheets using a pellet press. The infrared spectrometer was set with scanning parameters (wavenumber range 4000-500 cm⁻¹). -1 4 cm resolution -1 ), perform background scanning, then place the sample in for scanning to obtain an infrared spectrum (e.g. Figure 2 (As shown). Its crystal form belongs to the triclinic crystal system, and its space group is . P -1. This polymer consists of a Cu(II) ion, a 3-bbpa ligand, a 5-NIPA ligand, and a lattice water molecule. The central copper(II) ion is coordinated with two nitrogen atoms of the two 3-bbpa ligands and three oxygen atoms of the three 5-NIPA ligands. The Cu-N and Cu-O bond lengths are 2.010(3)-2.042(3) Å and 1.939(2)-2.209(2)) Å, respectively. The two copper(II) ions and the edge oxygen atoms of the 5-HIPA ligands alternately connect to form a one-dimensional [Cu2(5-HIPA)2] linear chain. The alternating connection of the copper(II) ion and the 3-bbpa ligand forms a one-dimensional [Cu(3-bbpa)] chain structure.

[0049] Its crystallographic parameters are shown in the table below:

[0050] crystal Cu-CP experimental <![CDATA[C 22 H 17 CuN5O9]]> molar mass / g 558.95 Temperature / K 296.0 Crystal system Triclinic crystal system Space Group -1 a / Å 9.8531(5) b / Å 9.8531(5) c / Å 12.2214(7) α / ° 90.161(2) β / ° 97.044(2) γ / ° 105.939(2) <![CDATA[Pore volume / Å 3 > 1165.94(11) Number of chemical formula units 2 <![CDATA[Calculation density g / cm 3 > 1.592 Linear absorption coefficient 1.001 Zero-order structure factor 570.0 Internal consistency factor 0.0831 Goodness of fit 1.020 Traditional / Weighted R Factor 0.0565 / 0.1205 R factor of all data 0.1106 / 0.1402

[0051] 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 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°. The powder X-ray diffraction pattern obtained in Example 1 matched the simulated pattern obtained from single-crystal data. Figure 3 ).

[0052] Example 4: Determination of urease activity inhibition by copper-based coordination polymers (hydroponic culture)

[0053] The jack urease used in the test was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 4 mL (10 KU / L) of sample and 4 mL of sample with different copper-based coordination polymer concentrations (samples were dissolved in DMSO: H2O = 1:1) were mixed thoroughly and pre-incubated at 37°C for 1 h. Then, 32 mL of phosphate buffer (pH 6.8, containing 500 Mm / L urea and 0.002% phenol red indicator) was added. The pH range was 6.8-7.7. The absorbance was measured at 570 nm using a UV spectrometer at 1-h intervals. The endpoint was determined by the phenol red indicator; the test was stopped when the solution changed from light orange-yellow to purple-red.

[0054] IC 50 Calculation:

[0055] 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. The IC50 is calculated as follows: 50 =5.12±0.01 μM / L, indicating that when this copper-based coordination polymer is used as a urease inhibitor, the half-inhibitory concentration is low, and the amount of additive is small ( Figure 4 Therefore, it can be concluded that the copper-based coordination polymer of the present invention can be used as a urease inhibitor in fertilizer urea.

[0056] Example 5: Determination of urease activity inhibition and nitration activity inhibition of copper-based coordination polymers (soil culture)

[0057] 1. Verification Experiment:

[0058] Taking the copper-based coordination polymer prepared in Example 1 as an example, a soil-based 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. A mixture of soil and fertilizer was added to a culture container, and the weight of the container and soil (A) was recorded. Then, 100 ml of water was evenly added to the soil surface, and the total mass (B) of the container, soil, and solution was recorded. The mass of the container and soil was measured before and after each soil sampling, and water was added to the original amount if the soil moisture was insufficient. After each water addition, the container opening was sealed with Para film and placed in a 25°C constant temperature incubator. Soil samples were taken on days 3, 7, 15, and 30 after incubation to measure soil urease and nitrification potential activities.

[0059] 2. Comparative experiment:

[0060] The experimental conditions were the same as those in the verification experiment, except that the copper-based coordination polymer of Example 1 was not added to the fertilizer.

[0061] 3. Results

[0062] 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 8.65%, 13.59%, and 7.55%, respectively. The significant reductions on days 3, 7, and 15 indicate that the copper-based coordination polymer has an inhibitory effect on urease activity. Figure 5 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 18.91%, 8.90%, and 6.56%, respectively. The decreases were most significant on days 7, 15, and 30. Figure 6 This indicates that copper-based coordination polymers have a dual-control effect of simultaneously inhibiting urease activity and nitration activity.

Claims

1. A method for preparing a copper-based coordination polymer, characterized in that, Includes the following steps: Step 1: Synthesize N using 3-aminopyridine and fumaric acid as raw materials. 1 N 4 -Bis(3-pyridyl)-2-butenamide; Step 2: Then add N 1 N 4 -Bis(3-pyridyl)-2-butenamide, CuCl2·2H2O and 5-nitroisophthalic acid were used to synthesize a copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)]·H2O, which is a fine blue crystal; Step 2 includes the following specific steps: Step 201: Mix CuCl2·2H2O and N 1 N 4 -Bis(3-pyridyl)-2-butenamide and 5-nitroisophthalic acid were placed in a hydrothermal reactor; Step 202: Add sodium hydroxide solution to the hydrothermal reactor, and then add distilled water to the hydrothermal reactor; Step 203: Place the hydrothermal reactor in an oven and calcine to obtain fine blue crystals. Then wash them with distilled water, filter and dry them to obtain the copper-based coordination polymer [Cu(3-bbpa)(5-NIPA)]·H2O; In step 201, CuCl2·2H2O reacts with N 1 N 4 The molar ratio of bis(3-pyridyl)-2-butenamide and 5-nitroisophthalic acid is 2:1:1.5; In step 202, the concentration of the sodium hydroxide solution is 0.025 mol / mL, and the volume ratio of sodium hydroxide solution to distilled water is 1:2; in step 203, the hydrothermal reactor is placed in an oven at 130 ℃ and fired for 4 days.

2. The method for preparing the copper-based coordination polymer according to claim 1, characterized in that, Step 1 includes the following specific steps: Step 101: Slowly add 3-aminopyridine dissolved in pyridine solution to pyridine solution of fumaric acid, and stir at room temperature; Step 102: Add triphenyl phosphite dropwise to the mixed liquid obtained in step 101, heat to reflux, let stand overnight at room temperature until a solid precipitates, filter, recrystallize with ethanol, and dry in air to obtain a powdery solid, i.e., N. 1 N 4 -Bis(3-pyridyl)-2-butenamide.

3. The method for preparing the copper-based coordination polymer according to claim 2, characterized in that, The molar ratio of 3-aminopyridine, trans-butenedioic acid, and triphenyl phosphite is 2:1:

1.

4. The method for preparing the copper-based coordination polymer according to claim 2, characterized in that, In step 101, stir for 30 min; in step 102, add triphenyl phosphite dropwise within 15 min after step 101 ends, and heat under reflux for 10 h.

5. The copper-based coordination polymer prepared by the method according to any one of claims 1-4, characterized in that, X-ray single-crystal diffraction experiments determined that the crystal form belongs to the triclinic crystal system, with space group [missing information]. P -1.

6. The application of the copper-based coordination polymer according to claim 5 in enhancing the efficiency of nitrogen fertilizer, characterized in that, It is added to nitrogen fertilizer as a fertilizer additive to inhibit the activity of soil urease and nitrifying bacteria.

7. The application according to claim 6, characterized in that, The nitrogen fertilizer mentioned is urea.

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