CuII-containing coordination polymer and preparation method and application thereof

Abstract

The invention belongs to the technical field of fertilizer additives, and particularly relates to a CuII-containing coordination polymer and a preparation method and application thereof.The preparation method comprises the steps that N, N '-bis (3-pyridinecarboxamide)-1, 2-ethane is synthesized with nicotinic acid and 1, 2-ethylenediamine as raw materials; the preparation method comprises the following steps: synthesizing a coordination polymer [Cu (1, 4-chdc) (3-dpye)]. 3H2O containing Cu II from N, N '-bis (3-pyridinecarboxamide)-1, 2-ethane, CuCl2. 2H2O and 1, 4-cycloadipic acid by using a hydrothermal method, so as to obtain a blue crystal. The product prepared by the invention is applied to urea as a fertilizer additive, so that the conversion of urea N to ammonium nitrogen and the conversion of ammonium nitrogen to nitrate nitrogen in the urea application process are reduced, and the volatilization of NH3 in the air and the subsequent volatilization of N2O after the urea is applied are reduced.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer additive technology, specifically relating to a Cu-containing additive. Ⅱ Coordination polymers, their preparation methods, and applications. Background Technology

[0002] Urease is an enzyme widely found in bacteria, plants, and soil, catalyzing the decomposition of urea into ammonia (NH3) and carbon dioxide (CO2). In agriculture, urease in the soil rapidly hydrolyzes urea into ammonium nitrogen, leading to nitrogen loss through volatilization and leaching, thus reducing nitrogen fertilizer utilization. Nitrifying bacteria are bacteria found in soil or water bodies that can convert ammonia nitrogen in the soil into nitrite and nitrate. The accumulation of these salts causes a decrease in soil pH, leading to soil acidification, damaging plant roots, and reducing nutrient absorption. This has negative impacts on human health and agriculture. Previous fertilizer additives were mostly single-function, had low inhibition rates, and were toxic, making the development of novel fertilizer additives crucial.

[0003] Coordination polymers (CPs) are a class of inorganic-organic hybrid materials formed by the self-assembly of a metal center (metal ion or metal cluster) and an organic ligand through coordination bonds. They possess diverse structures and tunable functions, demonstrating significant application potential in multiple fields. Copper can affect the enzyme activity of soil microorganisms, such as dehydrogenases and phosphatases, thereby interfering with their normal physiological metabolic processes. Simultaneously, copper can inhibit nitrification in soil, reducing the activity of nitrifying bacteria and thus affecting the soil nitrogen cycle. Therefore, by designing copper ions, ligand types, and synthesis conditions, efficient, structurally controllable, and stable copper-based coordination polymer inhibitors can be developed. Their application in fertilizers can effectively slow down the decomposition and transformation of urea nitrogen in the soil and prolong the retention time and fertilizer efficacy of urea in the soil. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a Cu-containing... Ⅱ The coordination polymer, its preparation method, and its application are described. As a fertilizer additive, it is used in urea to reduce the conversion of urea N to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen during urea application. It also reduces the volatilization of NH3 into the air after urea application and the subsequent volatilization of N2O, which causes serious problems including environmental and economic issues. This reduces nitrogen loss from urea and improves the utilization rate of urea in the soil.

[0005] This invention is achieved by providing a Cu-containing... Ⅱ The method for preparing the coordination polymer includes the following steps: Step 1: Synthesize N,N'-bis(3-pyridinecarboxamide)-1,2-ethane using nicotinic acid and 1,2-ethylenediamine as raw materials; Step 2: N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, CuCl2·2H2O, and 1,4-cyclohexane were synthesized using a hydrothermal method to contain Cu. Ⅱ The coordination polymer [Cu(1,4-chdc)(3-dpye)]·3H2O is a blue crystal.

[0006] Preferably, step 1 includes the following specific steps: Step 101: Slowly add 1,2-ethylenediamine to the pyridine solution of nicotinic acid while stirring; Step 102: Add triphenyl phosphite, heat to reflux, then concentrate, and let stand at room temperature until a white solid precipitates. Filter, recrystallize with ethanol, and dry to obtain a white powdery solid, namely N,N'-bis(3-pyridinecarboxamide)-1,2-ethane.

[0007] Further preferred, the molar ratio of 1,2-ethylenediamine, nicotinic acid, and triphenyl phosphite is 1:2:2, and the concentration of nicotinic acid in the pyridine solution is 0.08 g / mL.

[0008] Further optimization involves stirring for 15 minutes in step 1 and refluxing for 6 hours in step 2, concentrating the mixture to 5 mL.

[0009] Preferably, step 2 includes the following specific steps: Step 201: Place CuCl2·2H2O, N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, and 1,4-cyclohexane into 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 fire it to obtain fine blue crystals. Then wash with distilled water, filter and dry to obtain blue crystals, i.e., those containing Cu. Ⅱ The coordination polymer [Cu(1,4-chdc)(3-dpye)]·3H2O.

[0010] Further preferred, in step 201, the molar ratio of CuCl2·2H2O to N,N'-bis(3-pyridinecarboxamide)-1,2-ethane and 1,4-cyclohexanoic acid is 2:1:1.5.

[0011] Further preferred, in step 202, the concentration of the sodium hydroxide solution is 0.05 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 120 ℃ and fired for 4 days.

[0012] The present invention also provides the above-mentioned Cu-containing Ⅱ The preparation method of coordination polymers containing Cu Ⅱ The coordination polymer, as determined by X-ray single-crystal diffraction, belongs to the monoclinic crystal system with space group . C2 / c .

[0013] The present invention also provides the above-mentioned Cu-containing Ⅱ The application of coordination polymers as fertilizer additives to inhibit soil urease and nitrifying bacteria activity.

[0014] Preferably, in the above applications, the fertilizer is urea.

[0015] The beneficial effects of this invention are: it can effectively inhibit the activity of soil urease and nitrifying bacteria, delay the conversion of urea to ammonium nitrogen and ammonium nitrogen to nitrate nitrogen in the soil, so that nitrogen is retained in the soil for a longer period of time in the form of readily available nitrogen that is easily adsorbed by the soil; the inhibitor of this invention has low dosage, high inhibition rate, long half-life, low toxicity and low environmental impact, so it can be used in fertilizers. Attached Figure Description

[0016] Figure 1 This is a crystal unit cell diagram of the target product prepared in Example 3; Figure 2 This is the infrared absorption spectrum of the target product prepared in Example 3; Figure 3 This is a comparison between the powder X-ray diffraction pattern of the target product obtained in Example 3 and the simulated pattern of single crystal data; Figure 4 This is the assay of urease activity inhibition of the coordination polymer in Example 4 (hydroponic culture). Figure 5 This describes the urease activity inhibition effect of the coordination polymer in Example 5 (soil cultivation). Figure 6 This is the nitration activity inhibition effect of the coordination polymer in Example 5 (soil cultivation). Detailed Implementation

[0017] 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.

[0018] This invention provides a Cu-containing Ⅱ The preparation method of the coordination polymer includes the following steps: 1. Synthesis of N,N'-bis(3-pyridinecarboxamide)-1,2-ethane:

[0019] Step 101: Slowly add 1,2-ethylenediamine to the pyridine solution of nicotinic acid, the concentration of nicotinic acid is 0.08 g / mL, and stir for 15 min; Step 102: Add triphenyl phosphite, 1,2-ethylenediamine, nicotinic acid and triphenyl phosphite in a molar ratio of 1:2:2, heat under reflux for 6 h, then concentrate to 5 mL, let stand at room temperature until a white solid precipitates, filter, recrystallize with ethanol, dry to obtain a white powdery solid, namely N,N'-bis(3-pyridinecarboxamide)-1,2-ethane.

[0020] 2. Contains Cu Ⅱ Coordination polymers and their preparation methods Step 201: Place CuCl2·2H2O, N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, and 1,4-cyclohexane into a hydrothermal reactor at a molar ratio of 2:1:1.5; Step 202: Add sodium hydroxide solution to the hydrothermal reactor. The concentration of sodium hydroxide solution is 0.05 mol / mL. Then add distilled water to the hydrothermal reactor. The volume ratio of sodium hydroxide solution to distilled water is 1:2. Step 203: Place the hydrothermal reactor in a 120℃ oven and bake for 4 days to obtain fine blue crystals. Wash with distilled water, filter and dry to obtain blue crystals, i.e., those containing Cu. Ⅱ The coordination polymer [Cu(1,4-chdc)(3-dpye)]·3H2O.

[0021] Example 1

[0022] 1,2-Ethylenediamine (1 mL, 0.016 mol) was slowly added to a 50 mL pyridine solution of nicotinic acid (4.0 g, 0.032 mol). After stirring for 15 min, triphenyl phosphite (9 mL, 0.032 mol) was added, and the mixture was heated under reflux for 6 h. The solution was then concentrated to 5 mL, and after standing at room temperature for 24 h, a white solid precipitated. The solid was filtered, recrystallized from ethanol, and dried in air to obtain a white powdery solid with a yield of 63%. 0.034 g (0.2 mmol) of CuCl₂·2H₂O, 0.027 g (0.1 mmol) of N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, and 0.026 g (0.15 mmol) of 1,4-cyclohexane were placed in a hydrothermal reactor. 2 ml (0.1 mol) of sodium hydroxide solution was added to the reactor, followed by 4 ml of distilled water. The reactor was then heated in an oven at 120 °C for 4 days to obtain fine blue crystals. These crystals were washed repeatedly with distilled water, filtered, and dried to obtain blue crystals. The yield was approximately 37%.

[0023] Example 2

[0024] Example 1 was repeated, with a yield of 39%.

[0025] Example 3

[0026] Example 1 was repeated, with a yield of 38%. Examples 1-3 demonstrate that the method has a stable yield.

[0027] Take the Cu-containing sample prepared in Example 3 Ⅱ The structure of coordination polymers was determined: 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. Cu obtained from the blue bulk crystal prepared in Example 3 was used... Ⅱ Data obtained from secondary coordination polymer (SC-XRD), and further structural diagrams are shown below. Figure 1 (As shown). Cu obtained from the blue bulk crystals prepared in Example 3. Ⅱ Secondary coordination polymers were prepared using the KBr tableting method. 1-2 mg of sample was mixed and ground with 100-200 mg of dry KBr powder, then pressed into transparent tablets using a tablet press. An infrared spectrometer was set with scanning parameters (wavenumber range 4000-400 cm⁻¹, resolution 4 cm⁻¹) for background scanning, followed by scanning of the sample to obtain the infrared spectrum (e.g., ...). Figure 2 (As shown). Its crystal form belongs to the monoclinic system, and its space group is [missing information]. C2 / cThe central Cu(II) ion is a four-coordinate structure, coordinating with nitrogen atoms from the pyridine rings of two different L ligands and oxygen atoms from the two 1,4-cyclohexane anions to form a twisted "X" shape. Each metal Cu(II) ion is surrounded by four organic ligands (two bridging N,N'-bis(3-pyridylcarboxamide)-1,2-ethane and two bridging 1,4-cyclohexane), which can be considered as 4-connecting nodes. Each 1,4-cyclohexane connects two metal Cu(II) ions, which can be considered as 2-connecting nodes. The central Cu(II) ion forms a net-like structure with the N1 atom of the ligand N1,N4-bis(3-pyridyl)-2-butenamide through Cu-N1 (2.0323 Å) coordination bond and the O1 atom of the ligand 1,4-cyclohexane through Cu-O1 (1.9292 Å) coordination bond. Its crystallographic parameters are shown in the table below.

[0028] crystal Cu-CP experimental <![CDATA[C 22 H 30 CuN4O9]]> molar mass / g 558.04 Temperature / K 296.0 Crystal system Monoclinic Space Group C 2 / c a / Å 10.0596(13) b / Å 19.014(3) c / Å 12.6112(18) α / ° 90.000(0) β / ° 90.431(4) γ / ° 90.000(0) <![CDATA[Pore volume / Å 3 > 2412.1(6) Number of chemical formula units 4 <![CDATA[Calculated density g / cm 3 > 1.537 Linear absorption coefficient 0.966 Zero-order structure factor 1164.0 Internal consistency factor 0.0589( 1783) Goodness of fit 1.012 Traditional / Weighted R Factor 0.0589 / 0.1219 R factor of all data 0.1338 / 0.1515 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 3 matched the simulated pattern obtained from the single-crystal data. Figure 3 ).

[0029] Example 4 Cu Ⅱ Assay for the inhibition of urease activity by coordination polymers (hydroponic culture) The jack urease used in the test was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 4 mL (10 KU / L) and 4 mL of samples with different inhibitor concentrations (samples were dissolved in DMSO: H2O = 1:1) were mixed thoroughly and pre-cultured 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.

[0030] IC 50 Calculation: 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 =9.19±0.01 μM / L, indicating that when this Cu... Ⅱ Secondary coordination polymers have a low half-inhibitory concentration as urease inhibitors, requiring small amounts of additives. Figure 4 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.

[0031] Example 5 Cu Ⅱ Determination of urease and nitration activity inhibition by coordination polymers (soil culture) 1. Verification Experiment: 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 evenly 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.

[0032] 2. Comparative experiment: 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.

[0033] 3. Results The urease activity in the experimental soil was significantly lower than that in the control soil on days 3, 7, and 15, with decreases of 15.00%, 9.32%, and 3.69%, respectively. The most significant decreases were observed on days 3, 7, and 15, indicating that the 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 19.74%, 15.82%, and 1.58%, respectively. The most significant decreases were observed on days 7 and 15. Figure 6 This indicates that the coordination polymer has a dual-control effect of simultaneously inhibiting urease activity and nitration activity.

Claims

1. A Cu-containing Ⅱ The method for preparing coordination polymers is characterized in that, Includes the following steps: Step 1: Synthesize N,N'-bis(3-pyridinecarboxamide)-1,2-ethane using nicotinic acid and 1,2-ethylenediamine as raw materials; Step 2: N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, CuCl2·2H2O, and 1,4-cyclohexane were synthesized using a hydrothermal method to contain Cu. Ⅱ The coordination polymer [Cu(1,4-chdc)(3-dpye)]·3H2O is a blue crystal.

2. The Cu-containing [material] according to claim 1 Ⅱ The method for preparing coordination polymers is characterized in that, Step 1 includes the following specific steps: Step 101: Slowly add 1,2-ethylenediamine to the pyridine solution of nicotinic acid while stirring; Step 102: Add triphenyl phosphite, heat to reflux, then concentrate, and let stand at room temperature until a white solid precipitates. Filter, recrystallize with ethanol, and dry to obtain a white powdery solid, namely N,N'-bis(3-pyridinecarboxamide)-1,2-ethane.

3. The Cu-containing compound according to claim 2 Ⅱ The method for preparing coordination polymers is characterized by, The molar ratio of 1,2-ethylenediamine, nicotinic acid, and triphenyl phosphite is 1:2:

2. In the pyridine solution of nicotinic acid, the concentration of nicotinic acid is 0.08 g / mL.

4. The Cu-containing compound according to claim 2 Ⅱ The method for preparing coordination polymers is characterized in that, In step 1, the stirring time is 15 min; in step 2, the heating and reflux time is 6 h, and the volume is concentrated to 5 mL.

5. The Cu-containing [material] according to claim 1 Ⅱ The method for preparing coordination polymers is characterized in that, Step 2 includes the following specific steps: Step 201: Place CuCl2·2H2O, N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, and 1,4-cyclohexane into 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 fire it to obtain fine blue crystals. Then wash with distilled water, filter and dry to obtain blue crystals, i.e., those containing Cu. Ⅱ The coordination polymer [Cu(1,4-chdc)(3-dpye)]·3H2O.

6. The Cu-containing compound according to claim 5 Ⅱ The method for preparing coordination polymers is characterized by, In step 201, the molar ratio of CuCl2·2H2O to N,N'-bis(3-pyridinecarboxamide)-1,2-ethane and 1,4-cyclohexanoic acid is 2:1:1.

5.

7. The Cu-containing compound according to claim 5 Ⅱ The method for preparing coordination polymers is characterized by, In step 202, the concentration of the sodium hydroxide solution is 0.05 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 120 ℃ and fired for 4 days.

8. The Cu-containing compound according to any one of claims 1-7 Ⅱ The preparation method of coordination polymers containing Cu Ⅱ The coordination polymer, characterized in that, X-ray single-crystal diffraction experiments determined that the crystal form belongs to the monoclinic system, and the space group is [missing information]. C2 / c .

9. The Cu-containing compound according to claim 8 Ⅱ The application of coordination polymers is characterized by, It is added to fertilizers as a fertilizer additive to inhibit the activity of soil urease and nitrifying bacteria.

10. The application according to claim 9, characterized in that, The fertilizer is urea.

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