A method for preparing and slow-release bacteriostatic application of a tebuconazole complex

Abstract

The present application relates to a kind of preparation method and slow-release bacteriostatic application of pentazocine coordination polymer.The coordination polymer is with zinc as central metal, ligand is pentazocine and HCOO-R-COOH, wherein, R is selected from at least one of benzene ring, heterocycle and aliphatic group, constitute double-ligand type coordination polymer.A kind of preparation method of coordination polymer, it is the preparation method of any above-mentioned coordination polymer.Zinc salt, the HCOO-R-COOH and the pentazocine are sequentially added in DMF aqueous solution, under the condition of 0~200 ℃ oil bath, stirring 0.1~72 h, obtain the coordination polymer.The zinc salt includes at least one of zinc chloride, zinc sulfate and zinc nitrate.The coordination polymer of the present application has super high fungicide load, has excellent bactericidal effect and better ultraviolet light stability, shows double response release in the aspects of pH value and temperature.

Description

Technical Field

[0001] This invention belongs to the field of metal coordination polymer technology, specifically relating to a preparation method of tebuconazole-containing coordination polymerization and its sustained-release antibacterial application. Background Technology

[0002] Fungicides play an indispensable role in controlling crop diseases and pests in modern agriculture. However, due to a variety of factors, including their physicochemical properties (such as water solubility and chemical stability), application techniques (such as spraying and fumigation), and environmental factors (such as wind speed and temperature), up to 90% of fungicides degrade or volatilize into the environment before reaching their target site. Fungicides diffused into the environment may eventually enter the bodies of farmers and farm workers, affecting their health. Furthermore, fungicides successfully sprayed on plants are further wasted due to rapid hydrolysis, photodegradation, or microbial metabolism. Fungicide losses due to degradation can exacerbate environmental problems. All of the aforementioned fungicide residues and metabolites may increase food safety risks.

[0003] Compared to typical single-application fungicides, controlled-release (CR) fungicides can significantly prolong their effectiveness and reduce rapid degradation through a sustained-release mechanism. To date, various carriers have been used to construct CR systems, including polymer-based pesticide libraries such as sodium alginate and polylactic acid (PLA); lipid-based materials such as liposomes; porous inorganic materials such as mesoporous silica and carbon nanotubes; and metal-based materials such as coordination polymers (CPs). CPs, composed of organic linkers and metals or metal clusters, possess high specific surface area and porosity, as well as superior mechanical and chemical stability and customizability. They have been applied in gas adsorption and separation, catalysis, fluorescent labeling in bioimaging and detection, and controlled-release drug delivery systems.

[0004] In the field of controlled release and delivery of fungicides, CPs (concentrated phosphonates) act as antibacterial agents and carriers through the following mechanisms: generating antibacterial free radicals via photocatalysis; small CP particles penetrating and disrupting bacterial membranes, thereby stripping bacteria of their protective barrier; the released antibacterial fungicide participating in antibacterial activity; and the release of antibacterial metal ions or ligands upon structural collapse of CPs. Alternaria alternata is a fungal pathogen with high adaptability, capable of surviving in various environments such as water, soil, and air. Its potent pathogenicity and saprophytic nature allow it to rapidly infect newly harvested strawberries and apples, causing black spot disease and significant economic losses. Tebuconazole (TEB) is a triazole fungicide known for its high efficiency, low toxicity, and broad-spectrum activity, effectively treating and preventing plant diseases caused by A. alternata. However, due to its low water solubility, TEB is mainly formulated as an emulsifiable concentrate, easily hydrolyzed and photodegraded in the environment, resulting in low utilization, short shelf life, and significant environmental harm due to the use of organic solvents. Currently, the development of controlled-release systems for TEB aims to address these shortcomings.

[0005] For example, TEB microcapsules (Tebuc@PCN@P@C) prepared by layer-by-layer self-assembly of pectin and chitosan exhibit a dual response to pH and plant pathogen challenges. A fungicide delivery system (Tebu@ZnMOFs@CMC) with dual environmental responses to pH and cellulase was successfully constructed by loading tebuconazole into zinc-based metal-organic framework (ZnMOF) nanoparticles and further encapsulating them with carboxymethyl cellulose (CMC). Unfortunately, the TEB loading rate in these controlled-release delivery systems is less than 30%, and in practical applications, formulations require organic solvents, which also hinders complete drug release. Summary of the Invention

[0006] In view of this, the present invention provides a preparation method for tebuconazole-containing coordination polymerization and its sustained-release antibacterial application, which has excellent bactericidal effect.

[0007] The specific technical solution of the present invention is as follows:

[0008] A coordination polymer with zinc as the central metal and tebuconazole and HCOO-R-COOH as ligands, wherein R is selected from at least one of benzene ring, heterocyclic ring and aliphatic group, constituting a dual-ligand type coordination polymer.

[0009] Preferably, the HCOO-R-COOH is tribenzoic acid, isophthalic acid, p-aminobenzoic acid, 5-aminoisophthalic acid, biphenyl diphthalic acid, 5-hydroxyisophthalic acid, 1,4-naphthalenedicarboxylic acid, fumaric acid, malonic acid, citric acid, succinic acid, glutamic acid, nitrile acid, 2,5-dimethylbenzoic acid, 2,5-dichlorobenzoic acid, 3-chlorobenzoic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 4-phenylbenzoic acid, tribenzoic acid, naphtholic acid, m-methylbenzoic acid, 1,2 At least one of the following: 4-benzenetricarboxylic acid, 1,2,3-benzenetricarboxylic acid, 3,4-dimethylbenzoic acid, 2,5-dimethylphenylacetic acid, pyromellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, tartaric acid, malic acid, maleic acid, maleic acid, itaconic acid, mucoaconic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-carbonyldibenzoic acid, 3,3',4,4'-benzenetetracarboxylic acid oxide, and terephthalic acid.

[0010] A method for preparing a coordination polymer, which is any of the above-mentioned methods for preparing coordination polymers.

[0011] Preferably, the zinc salt, the HCOO-R-COOH and the tebuconazole are added sequentially to a DMF aqueous solution, heated in an oil bath and stirred to obtain the coordination polymer.

[0012] Preferably, the zinc salt includes at least one of zinc chloride, zinc sulfate, and zinc nitrate.

[0013] Preferably, the mixture is stirred at 0–200°C for 0.1–72 h.

[0014] Preferably, the molar concentration of the zinc salt is 0.01–100 mmol / L, the molar concentration of the HCOO-R-COOH is 0.01–100 mmol / L, the molar concentration of the tebuconazole is 0.01–100 mmol / L, and the molar ratio of the zinc salt, the HCOO-R-COOH, and the tebuconazole is (0.01–100):(0.01–100):(0.01–100).

[0015] The application of any of the above-mentioned coordination polymers or any of the above-mentioned preparation methods in the preparation of pesticides and fungicides.

[0016] Preferably, the coordination polymer is released in an aqueous solution environment.

[0017] The coordination polymer of this invention possesses an ultra-high fungicide loading, exhibits excellent fungicidal effect and good UV stability, and demonstrates dual-response release in terms of pH and temperature. This coordination polymer not only maintains the antifungal ability of the original fungicide TEB and prolongs the duration of its antifungal effect, but also exhibits better biocompatibility compared to TEB.

[0018] The preparation method of this invention involves the oil-thermal synthesis of coordination polymers. This method obtains pesticide-loaded coordination polymers through a one-step reaction, which is a shorter preparation route than traditional pesticide-loaded polymers. At the same time, the material obtained by this method can achieve a high loading rate of 73% for the pesticide tebuconazole, and can be widely used.

[0019] The coordination polymer of this invention can be fully deployed in applications, fully exert its bactericidal effect, and is environmentally friendly. Attached Figure Description

[0020] The accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 The diagram shows the structure of BUAP3 in Example 1; (a) shows the coordination environment of Zn(II), TPA2- and TEB, and (b) shows the one-dimensional chain of BUAP3.

[0022] Figure 2 The following are characterizations of BUAP3: (a) Single crystal structure and one-dimensional chain of BUAP3, (b) P-XRD spectrum (measured and simulated), (c) Particle size distribution, (d) SEM scan, and (e) EDS scan.

[0023] Figure 3 The results for BUAP3 determination are as follows: (a) FT-IR spectrum of BUAP3 determination, (b) TGA spectrum of BUAP3 determination, (c) adsorption-desorption curve of N2, and (d) logarithmic curve of BJH (adsorption) pore area and size.

[0024] Figure 4 (a) represents the Zeta potential of BUAP3. Figure 4 (b) XPS spectrum of BUAP3.

[0025] Figure 5 The results show the controlled-release performance of BUAP3; (a) shows the release at pH, (b) shows the release at temperature, (c) shows the cumulative release curve of TEB from BUAP3 in tap water, and (d) shows the release kinetic model of BUAP3 in tap water.

[0026] Figure 6 The results show the UV resistance test results; (a) is the photodegradation rate of TEB and BUAP3 as a function of time; (b) is the UV absorption spectrum of TEB and TPA; and (c) is the thermal storage stability analysis of TEB and BUAP3.

[0027] Figure 7 The results are as follows: (a) the in vitro antibacterial effects of BUAP3, TEB, TPA and EC50; (b) the growth rate of BUAP3, TEB and TPA; (c) the inhibition rate of BUAP3 and TEB; (d) the results of strawberry leaf infection experiment; and (e) the statistical data of the leaf infection experiment.

[0028] Figure 8 The results are as follows: (a) zebrafish survival rate, (b) seed germination rate after fungicide treatment, (c) seed growth length, (d) stem length, and (e) Marc-145 cytotoxicity test results. Detailed Implementation

[0029] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this application, not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application. Those skilled in the art should understand that modifications to specific embodiments of the present invention or equivalent substitutions for some technical features, without departing from the spirit of the technical solution of the present invention, should all be covered within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0030] A coordination polymer with zinc as the central metal and tebuconazole and HCOO-R-COOH as ligands, wherein R is selected from at least one of benzene rings, heterocycles, and aliphatic groups, forming a dual-ligand type coordination polymer. Zinc is not a heavy metal element and has low biotoxicity. Zinc is a trace element required by organisms and can be adequately absorbed as a nutrient. The compound HCOO-R-COOH can be tribenzoic acid, isophthalic acid, p-aminobenzoic acid, 5-aminoisophthalic acid, biphenyl diphthalic acid, 5-hydroxyisophthalic acid, 1,4-naphthalenedicarboxylic acid, fumaric acid, malonic acid, citric acid, succinic acid, glutamic acid, nicotinic acid, 2,5-dimethylbenzoic acid, 2,5-dichlorobenzoic acid, 3-chlorobenzoic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 4-phenylbenzoic acid, tribenzoic acid, naphtholic acid, m-methylbenzoic acid, 1,2,4-phenyltribenzoic acid, etc. Formic acid, 1,2,3-benzenetricarboxylic acid, 3,4-dimethylbenzoic acid, 2,5-dimethylphenylacetic acid, pyromellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, tartaric acid, malic acid, maleic acid, maleic acid, itaconic acid, mucoaconic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-carbonyldibenzoic acid, 3,3',4,4'-benzenetetracarboxylic acid oxide, and terephthalic acid, preferably terephthalic acid. The coordination polymer has a size from nanometers to micrometers, resulting in better adhesion after spraying.

[0031] The reactants of coordination polymers can be reacted in alcohol reagents or in aqueous DMF solutions.

[0032] The preparation method of coordination polymers may include the following steps:

[0033] (1) Mix DMF and water in a molar ratio of (1-100):(100-1) to obtain an aqueous solution of DMF.

[0034] (2) The zinc salt, terephthalic acid, and tebuconazole are sequentially added to the DMF aqueous solution and mixed thoroughly. The zinc salt includes at least one of zinc chloride, zinc sulfate, and zinc nitrate, preferably zinc chloride. The mixture is stirred in an oil bath at 0–200°C for 0.1–72 h. The heating temperature can be 0°C, 80°C, 90°C, 100°C, 120°C, 200°C, etc., and the stirring time can be 0.1 h, 0.5 h, 3 h, 6 h, 72 h, etc. The stirring speed is 120 rpm, and BUAP3 crystals rapidly grow and precipitate.

[0035] The preparation method of coordination polymers may further include the following steps:

[0036] (1) Mix DMF and water in a molar ratio of (1-100):(100-1) to obtain an aqueous solution of DMF.

[0037] (2) Add zinc salt, terephthalic acid, and tebuconazole to DMF aqueous solution sequentially and mix thoroughly. The zinc salt includes at least one of zinc chloride, zinc sulfate, and zinc nitrate, preferably zinc chloride. React at 80–120°C for 48–96 h, allowing BUAP3 crystals to grow freely. The preferred temperature is 120°C. Wash the reaction product with ethanol and water successively, and dry at room temperature to obtain a millimeter-sized white solid product.

[0038] The products obtained by the above preparation methods are of the same type and have the same characterization.

[0039] Example 1

[0040] A coordination polymer, with zinc as the central metal and TEB and terephthalic acid as ligands, forms a dual-ligand coordination polymer named BUAP3, and its structure is as follows: Figure 1 .

[0041] Example 2

[0042] 1. Materials and Methods

[0043] 1.1. Materials

[0044] Zinc chloride, H2TPA, TEB, TEB emulsion, and N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) sodium (HEPES) were supplied by J&K Scientific Ltd. N,N-dimethylformamide (DMF), methanol (chromatographic grade), and tetrahydrofuran (THF) were supplied by Aladdin Chemical Reagents Ltd. Durbeco Modified Eagle Medium (DMEM) and Potato Dextrose Agar (PDA) were purchased from Qingdao Hybo Biotechnology Co., Ltd. (Qingdao, China). Cell Counting Kit-8 (CCK-8) was purchased from Solar Energy Biotechnology Co., Ltd. (Beijing, China). Alternaria and Marc-145 cells were supplied by the Key Laboratory of Urban Agriculture in Northern China (Beijing, China). Ultrapure water was supplied by Milli- Produced using the EQ7000 ultrapure water purification system. Adult zebrafish, purchased from Beijing Yu Shen Aquarium.

[0045] 1.2. Instrument and Characteristic Identification

[0046] Measurements were taken at 400-4000 cm⁻¹ using a MAGNA-560 spectrometer. -1Fourier transform infrared (FT-IR) spectroscopy was performed. Powder X-ray diffraction (P-XRD) spectroscopy analysis was conducted on a Bruker D8 focusing diffractometer using a copper target tube and a graphite monochromator. P-XRD spectra were simulated using Mercury software based on Mercury single-crystal X-ray diffraction (SCXRD) data. Thermogravimetric analysis (TGA) was performed using a Rigaku Thermo+EVO2TG-DTA8121 analyzer, heated from room temperature to 800°C in a N2 environment. The specific surface area of ​​CP was determined using a BSD-PM1 micropore analyzer. The specific surface area was measured using the multi-point method (BET). The temperature of the sustained-release system was controlled using an SWC-LGE self-cooling freezing point tester. Elemental analysis (EA) was performed using a PerkinElmer 240C analyzer (for C, H, and N). High-performance liquid chromatography (HPLC) detection was performed using an Agilent 1200 series HPLC system (Agilent Technologies, USA), equipped with a G1314B detector (Agilent Technologies, USA) and a ZORBAX Eclipse XDB-C18 (4.6 mm × 150 mm, 5 μm).

[0047] 1.3.[Zn4(TEB)8(TPA)4] n Preparation

[0048] Synthesis of millimeter-scale large-size BUAP3: A Teflon-lined autoclave (100 mL) was prepared by adding zinc chloride (4 mmol, 0.2 mmol, 0.0272 g), H2TPA (1 mmol, 0.05 mmol, 0.0083 g), TEB (1 mmol, 0.05 mmol, 0.0153 g), and a mixed solvent (DMF:water = 1:1, 4 mL). The resulting mixture was maintained at 80 °C for 48 hours. A white crystalline solid was then filtered from the solvent and washed with water and methanol. The solid was then dried in the open air to give 0.0113 g of the final product. The synthesized crystals were analyzed by single-crystal X-ray diffraction. FT-IR (uniform, v / cm) -1 ): 3567(w), 1566(s), 1522(s), 1504(m), 1385(s), 1277), 1128), 1086) , 1013, 992), 839(s), 751(s), 696(w), 669(s), 657(s), 530(s), 401(s).

[0049] Synthesis of small-particle BUAP3: To further optimize the reduction of BUAP3 particle size, a round flask (100 mL) was prepared containing: zinc chloride (1 eq., 0.2 mmol, 0.0272 g), H2TPA (1.25 eq., 0.25 mmol, 0.0415 g), TEB (2.5 eq., 0.5 mmol, 0.153 g), and a mixed solvent (DMF:water = 1:1, 20 mL). The resulting mixture was rapidly stirred in an oil bath at 80 °C for 6 hours at a stirring speed of 120 rpm, and the final product was collected for subsequent experiments.

[0050] 1.4. Analysis of fungicide release

[0051] The concentration of TEB was determined by HPLC under the following conditions: injection volume 10 μL per sample, column temperature maintained at 30 °C, mobile phase of methanol-water (80:20, v / v) and effluent flow rate maintained at 1.0 mL / min. The UV detector was set to 220 nm.

[0052] 1.4.1. Environmentally Responsive Release

[0053] pH-responsive release: Prepare BUAP3 suspensions by dissolving CP (80 mg) and HEPES buffer (80 mL) in ultrapure water (80 mL). Then, stir the solution at room temperature, take 2 mL of each suspension, centrifuge after a fixed time, and add an equal volume of fresh buffer.

[0054] Temperature-responsive release: Except for maintaining different temperatures (10, 20, 30 °C) in HEPES buffer at pH 7, the above steps were followed. TEB concentration was determined by HPLC. Three replicates were performed under different conditions.

[0055] 1.4.2. Cumulative Release of TEB

[0056] BUAP3 (50 mg) was dispersed in tap water (1500 mL) and stirred. 2 mL samples were taken periodically, centrifuged, and analyzed by liquid chromatography. Then, the 2 mL sample of tap water and the centrifuged solid mixture were added back to the suspension. The concentration of TEB released from the BUAP3 suspension was determined by HPLC, and the cumulative release rate (CRR) of TEB was calculated using the equation method.

[0057]

[0058] In the formula, Mt is the amount of TEB released in each sampling time, t is the sampling time, and M is the theoretical amount of TEB in BUAP3.

[0059] 1.4.3. Release Kinetic Model

[0060] The release kinetics of BUAP3 were fitted using zero-order, first-order, Higuchian, and Ritger Peppas models, as follows:

[0061]

[0062] In the formula, t represents the amount of drug released at time t, M∞ represents the maximum amount of drug released indefinitely, k represents the rate constant of the bactericide, and n represents the diffusion index [Fick diffusion (n≤0.43), non-Fick, or non-Fick diffusion (n≤0.43)]. <n<1.0)]。

[0063] 1.5. Stability Test

[0064] 1.5.1. Determination of UV resistance

[0065] 16.5 mg of BUAP3 (12 mg based on TEB) was added to 50 mL of water to obtain a suspension with a concentration of 240 mg / L (based on TEB). Simultaneously, a TEB solution (240 mg / L) was prepared using a commercial emulsion-water dilution method. A simulated decomposition process was conducted at room temperature and irradiated with a 365 W mercury lamp at a wavelength of 254 nm. At regular time intervals, equal portions (1 mL) of the solution were taken and diluted with an equal volume of THF to completely dissolve the BUAP3 particles.

[0066] 1.5.2. Determination of thermal storage stability

[0067] Weigh 100 mg of BUAP3 sample, store it at 54℃ (±2℃) for 14 days, then dissolve it in THF by HPLC and determine the residual amount of TEB in BUAP3.

[0068] 1.6. Bioactivity Studies

[0069] 1.6.1. In vitro antifungal test

[0070] The fungicidal activity of BUAP3 against *Alternaria alternata* (provided by the Key Laboratory of Urban Agriculture in North China) was determined using the growth rate method and compared with that of TEB. 10 mg of BUAP3 was suspended in 100 mL of water and stirred. 2 mL of the suspension was collected, and the TEB concentration in the supernatant was determined. Before the antifungal test, BUAP3 suspension (concentration determined based on TEB), BUAP3 suspension (concentration determined based on free TEB solution), TEB solution, and TPA solution were used to prepare potato dextrose agar (PDA) concentrations of 0, 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 mg / L. Then, for each article, a 5 mm diameter mycelial cake was inoculated in the center of a 60 mm Petri dish and incubated at 28 °C until the fungal colony approached the edge of the plate. The colony diameter was determined using the cross-hatching method, and the inhibition rate was calculated using the equation method.

[0071]

[0072] In the formula, G1 is the diameter of the fungal cake in the control group, G x G0 represents the diameter of the fungal cake in the treatment group, and G0 represents the initial diameter of the fungal cake.

[0073] 1.6.2. Pot Experiment

[0074] This study evaluated the antifungal activity of BUAP3 and TEB against strawberry black spot disease. Strawberries were cultivated in a greenhouse at 28℃ and 80% humidity. BUAP3 suspension (50.0 mg / L based on the active ingredient of TEB) or TEB solution (50.0 mg / L) was sprayed onto strawberry leaves, followed by inoculation with fungal cakes (5 mm in diameter), and incubated at 28℃. A control group was treated with an equal volume of water. After a certain period, the spot area of ​​all test leaves was determined. Results were recorded after two weeks of incubation at 28℃. The lesion area on the leaves was calculated using ImageJ software.

[0075] 1.7. Safety evaluation during wheat seed germination

[0076] TEB aqueous solutions or BUAP3 (based on the active ingredient) suspensions at concentrations of 25.0, 50.0, and 100.0 mg / L were prepared. Wheat seeds (purchased from Beinong Market) were soaked in water for 2 days, dried, and then sprayed with tap water (control), TEB solution, or BUAP3 suspension. The seeds were then transferred to a dark chamber and cultured at 25°C for 7 days. The stem length and germination rate of the wheat seeds were recorded and calculated. Each experiment was repeated three times, and the average value of the results was taken.

[0077] 1.8. Acute toxicity to adult zebrafish

[0078] Acute toxicity tests of BUAP3 and TEB in adult zebrafish were conducted according to Test Guideline No. 203. Adult zebrafish measuring 2.5 (±0.5) cm were placed in chlorine-free tap water at 24°C, with a 10 / 14 dark / light cycle for one week. Then, aquariums (4 L, 20 cm × 16 cm × 13 cm) were filled half-volume with either TEB solute or BUAP3 suspension at concentrations of 0 (control), 1.0, 2.0, 4.0, 6.0, or 8.0 mg / L. Ten zebrafish were housed in each aquarium for 96 hours, and the LC50 (median lethal concentration) was calculated using GraphPadPrism 9.0.

[0079] 1.9. Cytotoxicological assays

[0080] The cytotoxic effects of BUAP3 and TEB on MARC-145 cells were evaluated using the CCK-8 assay. MARC-145 cells were propagated in DMEM (Durbeco Modified Eagle Medium) at 37°C in a humidified atmosphere containing 95% air and 5% carbon dioxide for 2–3 days in 96-well plates. Then, BUAP3 or TEB was introduced into the cell culture system at concentrations of 0 (control), 3.175, 6.25, 12.5, 25, and 50 (based on total active ingredient), and cultured for 24 h. After incubation with the test components, MARC-145 cells were further cultured for 24 h after the addition of CCK-8 reagent. At the end of the culture period, the absorbance of MARC-145 cells at 450 nm was measured using a microplate reader. Cell viability was calculated using equation software.

[0081]

[0082] Where A is the absorbance of the experimental group (including the absorbance of the medium, cells, test material, and CCK-8 solution), B is the absorbance of the control group (including the absorbance of the medium, cells, and CCK-8 solution), and C is the absorbance of the blank group (including the absorbance of the medium and CCK-8 solution).

[0083] 2. Results and Discussion

[0084] 2.1. Synthesis and Structure

[0085] BUAP3 was synthesized under hydrothermal conditions from H2TPA, zinc sulfate, and TEB. Single-crystal X-ray diffraction analysis revealed the structure of BUAP3, showing that the asymmetric unit comprises four crystal-independent Zn(II) ions and four TPA ions. 2- And 8 TEB ligands, such as Figure 2 As shown in (a), half of the ions and molecules are disordered in both parts, with an occupancy rate of 0.5. The central ion of Zn(II) is coordinated with 4 imidazole moles of N in TEB, TPA 2- The four O atoms of the two carboxylic acid groups are coordinated. Zn(II) ions and TPA 2- The ions alternate to form a zigzag one-dimensional chain, with two TEBs as terminal chains, bonded next to each metal center. [Zn4(TEB)8(TPA)4] n The structure indicates that TEB has a loading rate of 72.85% in the material.

[0086] 2.2. Characterization

[0087] Figure 2(a) Powder X-ray diffraction (P-XRD) spectra of BUAP3 and the simulated material. The P-XRD spectra are consistent with the simulation results, indicating that the BUAP3 material has high purity. In further studies, the morphology of BUAP3 was observed using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), such as... Figure 2 (c) and Figure 2 As shown in (d), the synthesized BUAP3 is a cuboid crystal with an average size of approximately 5 μm, as... Figure 2 As shown in (b). Figure 2 (e) shows the elemental spectrum of BUAP3 particles obtained by EDS, indicating the presence and uniform distribution of C, N, O, Cl, and Zn elements in BUAP3 particles.

[0088] The Fourier transform infrared (FT-IR) spectrum of BUAP3 revealed several characteristic peaks, which provide insights into the bonding interactions within functional groups and the framework, such as... Figure 3 As shown in (a), the asymmetric tensile vibration of the carbonyl group in the TPA2-carboxylic acid group occurs at 1573 cm⁻¹. -1 The symmetrical tensile vibration occurred at 1375cm. -1 Around 1680 cm⁻¹, there are no obvious peaks, indicating the lack of free carboxylic acid groups, confirming that the carboxylic acid groups are completely coordinated with the Zn(II) center. At 1215 cm⁻¹... -1 The peak at 1510 cm⁻¹ is due to the stretching vibration of the CO bonds. -1 The peak value belongs to the vibrational absorption of -C=N in the heterocycle, at 679 cm⁻¹. -1 The peak at 1379 cm⁻¹ originates from vibrational absorption of the C-Cl bond and... -1 This corresponds to the tensile vibration of -OH in TEB.

[0089] Thermogravimetric analysis (TGA) of BUAP3, such as Figure 3 As shown in (b), the thermal degradation-induced weight loss of TEB and BUAP3 occurred at approximately 250℃ and 290℃, respectively. The weight loss curve of BUAP3 abruptly decreased from 290℃ to 350℃, and an inflection point appeared after solidification above 350℃, likely due to the decomposition of the TPA2-ligand. With increasing temperature, a relatively stable sample weight was observed above 550℃, with residual sample weight decreasing from 15.2% to 11.9%.

[0090] Figure 3 (c) shows the N2 adsorption-desorption isotherm and BUAP3. A hysteresis line exists between 0.2 and 1.0 relative pressures (P / P0), therefore the isotherm can be classified as Type IV. The Barrett-Joyner-Halenda (BJH) graph shows the pore size distribution, as... Figure 3As shown in (d), the average pore size calculated according to the BJH model is 10.1 nm, proving that BUAP3 exhibits a mesoporous structure and a specific surface area of ​​1.58 m² / g according to the multi-point method.

[0091] Figure 4 (a) shows the zeta potential of BUAP3 suspensions at different pH conditions. The average surface potentials of the suspensions at pH 5, 7, and 9 were 5.7, -22.4, and -34.8 mV, respectively. In the pH 7 test group, BUAP3 had the largest absolute value of surface charge, indicating increased electrostatic repulsion between particles, which made the material easier to disperse in an aqueous environment.

[0092] The chemical composition and elemental valence states of BUAP3 material were evaluated using the XPS method. Figure 4 XPS spectra in (b) show that BUAP3 contains Zn, C, O, N, and Cl. In the high-resolution spectrum, the peak of C 1s at 284.8 eV belongs to C; the peak of O 1s at 532.6 eV comes from CO; for N 1s and Cl 2p, N and Cl elements in TEB in BUAP3 were detected, respectively, providing evidence for the successful loading of TEB.

[0093] 2.3. Controlled-release performance of BUAP3

[0094] Table 1. TEB release kinetic equations for BUAP3 in the aquatic environment.

[0095] Functional model Fitting function <![CDATA[R 2 ]]> Zero order y = 1.34t + 32.99 0.81 First order <![CDATA[y=95.48(1-e -0.12t )]]> 0.94 Shiguchi <![CDATA[y=12.29t 0.5 +14.04]]> 0.95 Ritger Peppas <![CDATA[y=25.35t 0.35 ]]> 0.97

[0096] BUAP3's TEB underwent a cumulative release test in an aqueous environment, such as... Figure 5 As shown in (c), under stirring conditions, TEB was rapidly released within the first 40 hours, reaching approximately 98% release after this point. This indicates that BUAP3 can almost completely release TEB. The remaining 2% of releasable TEB may be due to minor impurities in the material and measurement errors caused by the experimental equipment. Simultaneously, the release behavior of BUAP3 in tap water was fitted using four common bactericide release kinetic models, such as... Figure 5 (d) is shown. As shown in Table 1, the R values ​​for zero-order, first-order, Higucci, and Ritger Peppas models are... 2 The values ​​are 0.81, 0.94, 0.95, and 0.97, respectively. In other words, the release behavior of BUAP3 in tap water is more consistent with the Ritger-Peppas model. The release index n in this model is 0.35 < 0.45, indicating that the release of tebuconazole is Fick diffusion (Case I), that is, its release conforms to the diffusion process of the polymer.

[0097] Figure 5 (a) shows the real-time release concentrations of TEB from BUAP3 in aquatic environments with pH values ​​of 5, 7, and 9. At pH = 9, TEB was rapidly released from 0 to 10 hours, then the release rate gradually slowed, eventually stabilizing at around 30 mg / L after approximately 25 hours. At pH = 5, TEB was rapidly released in the first 5 hours, then released slowly for about 25 hours, eventually stabilizing at around 30 hours. At pH = 7, TEB was released slowly until approximately 45 hours, at which point the concentration stabilized. In summary, BUAP3 exhibits both acidic and alkaline release reactions, with the alkaline condition showing a faster reaction and the acidic condition showing a more stable reaction. When the pH of the external liquid environment changed, the surface potential of PDPC3 also changed significantly. This phenomenon altered the charge state of the BUAP3 particle surface, disrupting the original coordination electrostatic adsorption equilibrium between the BUAP3 particles and the TEB bactericide.

[0098] Release curves under different temperature conditions (i.e., 10, 20, and 30°C simulating day and night alternation) are shown below. Figure 5 As shown in (b), the release rate of TEB is positively correlated with temperature, and the TEB concentration remains stable at around 30 h. The results show a significant difference due to temperature; lower temperatures slow molecular motion, and the TEB fungicide molecules in the coordinated form of BUAP3 particles do not receive sufficient energy, making it difficult for them to break free from particle constraints and the limitations of the coordinating bonds, resulting in slow release of the TEB fungicide to the solution. In summary, BUAP3 exhibits a temperature-responsive release effect.

[0099] 2.4. UV protection ability

[0100] Figure 6 (a) Degradation rates of BUAP3 and TEB after different light exposure times. TEB degraded rapidly at the beginning of light exposure, then the degradation rate stabilized, finally reaching 95% at 3.5 h. Meanwhile, the degradation rate of BUAP3 at 3.5 h was only about 35%, meaning that BUAP3 can significantly improve the photostability of TEB-loaded TEB.

[0101] Figure 6 (b) The UV absorption of TPA and TEB at 10 mg / L was measured separately. Many factors can be considered to improve the UV stability of BUAP3. Ligand stability can always be improved by incorporating high-density materials. Compared to TEB, H2TPA exhibits higher UV absorption in the 215-275 nm wavelength range; therefore, the protection of TEB from radiation-induced degradation by the TPA ligand may be another reason for the stronger stability of TEB in BUAP3.

[0102] Figure 6(c) This section explores the thermal stability of BUAP3, showing the change in residual TEB content over time at an ambient temperature of 54°C. By day 14, the residual TEB content remained at approximately 95% of its initial value, indicating that long-term high-temperature storage does not excessively affect the stability of BUAP3. Furthermore, in the TGA test, the weight of BUAP3 only began to decrease after reaching 270°C. In conclusion, BUAP3 exhibits good thermal stability.

[0103] 2.5. Inhibitory effect against Alternaria alterniflora

[0104] The antibacterial activity of BUAP3 against strawberry black spot was evaluated by using the antibacterial activity of TEB against strawberry leaf black spot. Figure 7 (a) Inhibitory effects of BUAP3, TEB, and TPA at different concentrations. The antifungal activity of all three compounds increased in a concentration-dependent manner. Among them, such as Figure 7 As shown in (c), the EC50 value of BUAP3 was 1.98 ± 0.28 mg / L, while the EC50 value of TEB was 2.00 ± 0.32 mg / L, indicating that the antifungal activity of BUAP3 was slightly better than that of TEB. Figure 7 The bar chart in (b) clearly shows that TPA has a significant antifungal effect when the concentration reaches 2 mg / L. It can be inferred that the antifungal effect of BUAP3 is slightly enhanced compared to TEB, which is due to the TPA2 supplement in BUAP3.

[0105] Pot experiments further evaluated the antibacterial activity of BUAP3 material against strawberry black spot. Figure 7 As shown in (d) and (e), compared with the TEB group and the control group, the strawberry leaves in the BUAP3 granule group had a smaller damaged area at the same time point, indicating that BUAP3 has good antifungal activity in live plants. As time progressed, when lesions began to appear in the TEB group and continued to expand, the BUAP3 granule group continued to exhibit good antifungal activity.

[0106] 2.6. Biosafety Assessment

[0107] In practical applications, fungicides inevitably enter the aquatic environment due to leaching and other factors, thus affecting the safety of non-target organisms. Zebrafish are an important biological sample for acute toxicity testing of fungicides in aquatic environments. Figure 8 (a) Shows the acute toxicity of TEB and BUAP3 to zebrafish over an experimental period of 24–96 h. At the same intergroup concentrations, the LC50 of free TEB... 50The concentration reached 3.3 mg / L, while the legality of BUAP3 particles at a concentration of 10 mg / L was approximately 7% and 13%, respectively. This indicates that BUAP3-immobilized TEB has good biocompatibility.

[0108] TEB can inhibit wheat germination by disrupting the redox homeostasis of wheat. Figure 8 (b), (c), and (d) show the germination rate and stem length of wheat seeds treated with TEB and BUAP3, respectively. Compared with the control group (without any pesticide treatment), both the TEB and BUAP3 groups showed inhibitory effects on wheat seeds. At the same concentration, the germination rate of wheat seeds in the BUAP3 group was approximately 30% higher than that in the TEB group at different pesticide concentrations. Furthermore, the stem length of wheat seeds in the BUAP3 group was approximately 2 cm longer than that in the TEB group. These results indicate that BUAP3 has significantly lower toxicity to wheat germination than TEB.

[0109] BUAP3 toxicity to Marc-145 cells, such as Figure 8 As shown in (e). The results indicate that both BUAP3 and TEB exhibit concentration-dependent cytotoxicity. However, at the same concentration, the cell viability of the BUAP3 group was greater than that of the TEB group. In particular, when the concentration reached 50 mg / L, almost no cells in the TEB group survived, while the cells in the BUAP3 group maintained a high survival rate of nearly 50%.

[0110] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coordination polymer, characterized in that, With zinc as the central metal and tebuconazole and terephthalic acid as ligands, a dual-ligand coordination polymer is formed. Its asymmetric unit includes four crystal-independent Zn(II) ions and four TPA ions. 2- And 8 of the tebuconazoles, the central ion of Zn(II) is coordinated with the N of 4 imidazoles in the tebuconazole, the TPA 2- The four O atoms of the two carboxylic acid groups are coordinated, and the Zn(II) ion and the TPA 2- They alternate to form a zigzag one-dimensional chain, with two of the tebuconazoles as terminal chains, attached next to each metal center.

2. The method for preparing the coordination polymer according to claim 1, characterized in that, The zinc salt, the terephthalic acid, and the tebuconazole were sequentially added to an aqueous DMF solution, and the mixture was heated in an oil bath and stirred to obtain the coordination polymer.

3. The preparation method according to claim 2, characterized in that, The zinc salt includes at least one of zinc chloride, zinc sulfate, and zinc nitrate.

4. The preparation method according to claim 2, characterized in that, Stir at 0~200℃ for 0.1~72h.

5. The preparation method according to claim 2, characterized in that, The molar concentration of the zinc salt is 0.01~100 mmol / L, the molar concentration of the terephthalic acid is 0.01~100 mmol / L, the molar concentration of the tebuconazole is 0.01~100 mmol / L, and the molar ratio of the zinc salt, the terephthalic acid and the tebuconazole is (0.01~100):(0.01~100):(0.01~100).

6. The application of the coordination polymer according to claim 1, or the coordination polymer obtained by any of the preparation methods according to claims 2 to 5, in the preparation of pesticides and fungicides.

7. The application according to claim 6, characterized in that, The coordination polymer is released in an aqueous solution environment.

Images