Zn-mof loaded phenylethanol composite material, and preparation method and application thereof

Abstract

This invention discloses a Zn-MOF-loaded phenylethanol composite material, its preparation method, and its applications, belonging to the field of metal-organic framework materials. The Zn-MOF-loaded phenylethanol composite material uses Zn-MOF as a carrier, and phenylethanol is successfully loaded into its pores or surface using a magnetic stirring method. Experiments confirm that phenylethanol is effectively loaded, and the composite material maintains good crystal structure and thermal stability, with a high encapsulation efficiency of 72.63%. The release rate is slow; compared to the release rate of free phenylethanol (1.17% / h), the release rate of phenylethanol@Zn-MOF is 0.024% / h, which can prolong its action period and improve bioavailability. It can be used as a flavoring sustained-release agent, antibacterial packaging material, or drug delivery carrier in the food and functional materials fields. This invention also demonstrates that it can promote plant growth, increase yield, and induce plant resistance. This invention provides a new technical path for the stabilization and long-term utilization of volatile active ingredients, laying the foundation for the development and application of green and environmentally friendly functional composite materials.

Description

Technical Field

[0001] This invention relates to a Zn-MOF-loaded phenylethanol composite material, its preparation method and application, belonging to the field of metal-organic framework materials. Background Technology

[0002] Phenylacetyl alcohol (2-phenylethanol or β-phenylethanol, CAS 60-12-8) is an important aromatic alcohol compound, naturally found in the fragrances of roses, violets, and other flowers, as well as fruits such as grapes, strawberries, and apples. It is a colorless liquid with a typical rose aroma and is soluble in water and most organic solvents. It has wide applications in food additives, pharmaceuticals, cosmetics, and agriculture. Phenylacetyl alcohol belongs to the phenylphenylpropane class of volatile compounds. Besides its use as a food additive, it also possesses various biological activities such as antibacterial, antioxidant, anti-inflammatory, and growth-inducing effects, showing good application potential in the pharmaceutical, cosmetic, and agricultural fields. However, the high volatility and low bioavailability of phenylethanol severely restrict the effective exertion of its biological activities. Therefore, it is urgent to develop practical strategies to solve these problems.

[0003] Loading phenylethanol onto a carrier and controlling its release rate is a commonly used technique, and developing carrier materials that combine high loading capacity with good controlled-release performance is the core of this technology. Metal-organic frameworks (MOFs), as novel carriers, possess high specific surface area and tunable pore size, making them ideal for loading fragrances. MOFs utilize their strong adsorption capacity, ease of regeneration, and high porosity to load substances. When the pore size is larger than the substance, it can be loaded into the pores through physical or chemical means. Once in a specific environment, it can be slowly released over time, reducing its toxicity and side effects. Based on the tunability of MOFs, specific nutrients (macronutrients, micronutrients, or mixed multinutrients) can be introduced at the molecular level according to the crop's nutrient requirements during MOF design and synthesis. Existing technology shows that loading epigallocatechin gallate (EGCG) onto Zn-MOF improves EGCG stability and efficacy, promotes wound healing and reduces local inflammation in diabetic mice, and has good application safety. Patent CN201811277472.6 discloses a reprocessable slow-release aroma material, its preparation method, and its application. The method involves mixing 2-phenylethanol, 2-methylimidazole, and zinc nitrate together, stirring for 10 minutes, and then subjecting the mixture to ultrasonic treatment to obtain a 2-phenylethanol@ZIF-8 material that slowly releases the aroma of 2-phenylethanol. The proportions of the raw materials are as follows: zinc nitrate 0.02–0.4 g, 2-methylimidazole 0.12–2.4 g, and 2-phenylethanol 5–100 mL. Results showed that the material slowly releases 2-phenylethanol when placed in air, and the aroma of 2-phenylethanol is still released after two months. However, the characterization of the composite material is incomplete; the slow-release performance of phenylethanol is evaluated only qualitatively, and the patent only relates to the field of slow-release technology of phenylethanol as a fragrance. It does not address the improvement of the growth-promoting and resistance-inducing effects of phenylethanol after loading, nor its application verification in the agricultural field. Therefore, is it possible to provide a composite material and a complete loading process for achieving high-load controllable sustained release of phenylethanol, thereby solving the problem of insufficient sustained efficacy of phenylethanol in field applications? Summary of the Invention

[0004] To address the above technical problems, this invention provides a Zn-MOF-loaded phenylethanol composite material, its preparation method, and its application.

[0005] This invention protects a Zn-MOF-loaded phenylethanol composite material, wherein the Zn-MOF-loaded phenylethanol composite material uses Zn-MOF as a carrier skeleton, and phenylethanol is stably loaded into the pores or surface of Zn-MOF to form a core-shell type or pore-filled type sustained-release composite material; the Zn-MOF is a white rectangular powder crystal synthesized from zinc acetate and 1,3,5-tribenzoic acid through a hydrothermal reaction.

[0006] This invention also protects a method for preparing a Zn-MOF-loaded phenylethanol composite material, comprising the following steps: mixing phenylethanol and Zn-MOF at a feeding ratio of 1:0.5-2.5, adjusting the pH to 4-8, stirring continuously with a magnetic stirrer at 4-35℃ for 3-9 h, letting stand for more than 24 h, centrifuging at 10000 r / min for 10 min at 4℃, washing twice with anhydrous ethanol and collecting the supernatant, filtering with a filter with a pore size of 0.45 µm to obtain the Zn-MOF-loaded phenylethanol composite material.

[0007] Further, the preparation method of the Zn-MOF is as follows: Weigh 9.170 g of zinc acetate, add 84.4 mL of pure water, and dissolve and mix well to obtain solution A; weigh 5.25 g of 1,3,5-tribenzoic acid, add 83.4 mL of anhydrous ethanol, and dissolve and mix well to obtain solution B; add solution B to solution A, sonicate and mix for 10 min, place in a high-pressure reactor lined with polytetrafluoroethylene, place the high-pressure reactor in an oven, react at 120℃ for 10 h, close the oven, and allow the high-pressure reactor to cool to room temperature. After removal, centrifuge and wash with ethanol and pure water at 4℃, 5000 r / min for 10 min, and dry under vacuum at 60℃ to obtain white rectangular powder crystals.

[0008] Preferably, the feeding ratio of phenylethanol to Zn-MOF is 1:0.5-1.5.

[0009] Preferably, the pH value is 5-7.

[0010] Preferably, the stirring time is 3-6 hours.

[0011] This invention also protects the application of the Zn-MOF-loaded phenylethanol composite material in promoting growth, increasing yield, and inhibiting diseases in tomatoes and rice.

[0012] Furthermore, the diseases mentioned are early blight and viral diseases of tomatoes, and leaf spot and leaf blast of rice and sesame.

[0013] Compared with the prior art, the present invention has the following technical effects: The phenethyl alcohol@Zn-MOF composite material provided by this invention uses a metal-organic framework Zn-MOF as a carrier and was successfully synthesized through a combination of magnetic stirring and hydrothermal reaction. The resulting crystal structure is regular and the morphology is uniform. The preparation process is simple and efficient, with mild reaction conditions, and possesses good reproducibility and potential for large-scale production. The Zn-MOF synthesis in this invention is simple and scalable, and its pore size is suitable for small molecule phenethyl alcohol (molecular weight 122.16). 2+ The ligand 1,3,5-tribenzoic acid is relatively safe for the environment.

[0014] This invention systematically characterized phenethyl alcohol@Zn-MOF using scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results showed that phenethyl alcohol was successfully loaded into the channels or surface of Zn-MOF, and the composite material maintained a complete crystal structure and good thermal stability, further confirming the effective encapsulation of active ingredients by Zn-MOF as a carrier. Furthermore, the response surface optimization model established using Design Expert 13 software demonstrated high prediction accuracy, and the experimental verification results showed a high degree of agreement with the optimization results, fully demonstrating the scientific nature and reliability of the process design.

[0015] The encapsulation efficiency obtained by the method of this invention can reach up to 73.52%, with an actual verified value of 72.63%. The Zn-MOF-loaded phenylethanol composite material provided by this invention has an average release rate of 0.024% / h. After 12 days, the release rate of phenylethanol is only 6.36%, and it is predicted that after two months, the release rate of phenylethanol in this composite material will be 34.56%. Therefore, this composite material can effectively reduce the release rate of phenylethanol. Its application in crop cultivation can extend its action period, improve utilization efficiency, achieve long-term sustained release, and enhance the growth-promoting and resistance-inducing effects of phenylethanol. Experiments also demonstrated that the composite material provided by this invention increased the stem diameter and chlorophyll content of tomatoes, effectively promoting tomato yield, with a theoretical yield increase of 6% compared to the control (CK). The soluble solids, lycopene, and vitamin C content of this composite material increased by 3.43%, 44.62%, and 41.75% respectively compared to single-spray phenylethanol. It effectively controlled early blight and viral diseases in tomatoes, reducing the incidence and disease index of early blight by 40.00% and 29.55% respectively compared to the CK, and the incidence and disease index of viral diseases by 24.99% and 31.82% respectively. When sprayed on rice, this composite material increased plant height, fresh weight, dry weight, and yield, with an actual yield increase of 15.30% compared to the CK. It also effectively controlled rice leaf blast and sesame leaf spot, reducing the incidence and disease index of rice leaf blast by 42.59% and 54.02% respectively compared to the CK, and the incidence and disease index of sesame leaf spot by 54.78% and 52.44% respectively.

[0016] The synthesis process of this invention uses water and ethanol as solvents entirely, avoiding the use of toxic organic solvents and conforming to the concept of green chemistry. Meanwhile, the prepared phenylethanol@Zn-MOF can be used in fields such as sustained-release fragrances, antibacterial packaging, and functional materials, showing broad application prospects. This material is inexpensive to prepare, easy to operate, and highly environmentally compatible, providing a new technical route for the stabilization and controlled-release utilization of volatile active ingredients, offering significant economic and social benefits. Attached Figure Description

[0017] Figure 1 Microscopic comparison images of Zn-MOF before and after synthesis; Figure 2 The diagram shows the influence of conditions on Zn-MOF loading of phenylethanol; where Figure 2 A, Figure 2 B. Figure 2 C and Figure 2 D represents the effect of different ingredient ratios, temperatures, times, and pH values ​​on the encapsulation efficiency; Figure 3 The response surface plot (left) and contour lines (right) show the effect of the interaction of different factors on the encapsulation efficiency. Figure 4 SEM images of Zn-MOF, phenethyl alcohol@Zn-MOF, and phenethyl alcohol + Zn-MOF; among them Figure 4 A is the SEM image of Zn-MOF. Figure 4 B is a SEM image of the physical mixture of phenylethanol and Zn-MOF. Figure 4 C is the SEM image of the phenylethanol@Zn-MOF inclusion complex; Figure 5 TEM images of Zn-MOF, phenethyl alcohol@Zn-MOF, and phenethyl alcohol + Zn-MOF; among them Figure 5 A is the TEM image of Zn-MOF. Figure 5 B is a TEM image of the physical mixture of phenylethanol and Zn-MOF. Figure 5 C is a TEM image of the phenylethanol@Zn-MOF inclusion complex; Figure 6 PXRD characterization diagrams of Zn-MOF, phenethyl alcohol@Zn-MOF, and phenethyl alcohol + Zn-MOF; Figure 7 The FTIR spectra are for phenethyl alcohol, Zn-MOF, phenethyl alcohol@Zn-MOF, and phenethyl alcohol + Zn-MOF. Figure 8 TGA images of Zn-MOF, phenethyl alcohol@Zn-MOF, and phenethyl alcohol + Zn-MOF; Figure 9 Release curves of phenethyl alcohol and phenethyl alcohol@Zn-MOF; Figure 10 This is a chart showing the growth indicators of field tomatoes, in which... Figure 10 A represents stem thickness. Figure 10 B represents the chlorophyll content; Figure 11 A comparison chart of field tomato yields; Figure 12 This is a chart showing the quality indicators of field-grown tomatoes; among which... Figure 12 A is a comparison image of the fruits. Figure 12 B is a comparison chart of soluble solids in tomatoes. Figure 12C is a comparison chart of lycopene content. Figure 12 D is a comparison chart of vitamin C content in tomatoes; Figure 13 Map showing a survey of diseases affecting field tomatoes; among which Figure 13 A represents the incidence rate of early epidemic disease. Figure 13 B represents the early epidemic disease severity index. Figure 13 C represents the incidence rate of viral diseases. Figure 13 D represents the viral disease severity index; Figure 14 This is a graph showing the growth indicators of paddy rice at maturity; among which... Figure 14 A is a comparison chart of rice growth. Figure 14 B represents plant height. Figure 14 C represents fresh weight. Figure 14 C represents dry weight; Figure 15 This is a graph showing the yield of paddy rice at maturity; among which... Figure 15 A represents the weight of 1000 grains. Figure 15 B represents the seed setting rate. Figure 15 C represents the number of grains per ear. Figure 15 D represents the number of effective ears; Figure 15 E represents the theoretical output; Figure 15 F represents the actual output; Figure 16 Map showing a survey of diseases during the ripening stage of paddy rice; among which Figure 16 A represents the incidence rate of rice leaf blast. Figure 16 B represents the rice leaf blast disease index. Figure 16 C represents the incidence rate of rice leaf spot disease. Figure 16 D represents the severity index of rice leaf spot disease. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to specific embodiments. All materials are commercially available.

[0019] Example 1 Synthesis of Zn-MOF Weigh 9.170 g of zinc acetate (Zn(NO3)2·6H2O, 99.0%), add 84.4 mL of pure water, and dissolve and mix well to obtain solution A. Weigh 5.25 g of 1,3,5-trisimilar tribenzoic acid (C9H6O6, 98.0%), add 83.4 mL of anhydrous ethanol (CH3CH2OH, 99.7%), and dissolve and mix well to obtain solution B. Add solution B to solution A, sonicate and mix for 10 min, place in a 25 mL polytetrafluoroethylene-lined high-pressure reactor, place the high-pressure reactor in an oven, react at 120℃ for 10 h, close the oven, and allow the high-pressure reactor to cool to room temperature. After removal, centrifuge twice with ethanol and pure water at 4℃, 5000 r / min for 10 min, wash off excess solvent, and dry under vacuum at 60℃ to obtain white rectangular powder crystals. Figure 1 ).

[0020] Example 2 Preparation of phenylethanol@Zn-MOF The experimental method is as follows: Zn-MOF material and phenylethanol were mixed at a feed ratio of 1:0.5-2.5, and the pH was adjusted to 4-8. The mixture was stirred continuously with a magnetic stirrer at 4-35℃ for 3-9 h. The sample was then left to stand for at least 24 h, centrifuged at 10000 r / min for 10 min at 4℃, and washed twice with anhydrous ethanol to remove unloaded phenylethanol from the surface. The supernatant was collected. After filtration through a 0.45 µm filter, the supernatant was analyzed by GC-MS to determine the content of unloaded phenylethanol. The encapsulation efficiency of phenylethanol@Zn-MOF was calculated using the following formula. After preparation, the phenylethanol@Zn-MOF was dried in a freeze dryer and stored for later use.

[0021]

[0022] This invention sets 5 sets of feeding ratios (m 苯乙醇 :m Zn-MOF Loading tests were conducted at five loading temperatures (4, 10, 15, 25, 35℃), five loading times (3, 4.5, 6, 7.5, 9 h), and five pH values ​​(4, 5, 6, 7, 8) to determine the encapsulation efficiency.

[0023] The GC-MS detection procedure is as follows: ① Plotting the phenylethanol standard curve. A 100 mg / L phenylethanol / ethanol stock solution was prepared and diluted to six standard solutions of 5, 7, 9, 10, 12, and 20 mg / mL. 1 μL of each standard solution was injected. The standard curve was plotted with the peak area of ​​phenylethanol as the ordinate and the concentration of phenylethanol as the abscissa. ② GC conditions: Agilent 19091J-413 column (30.0 m × 320 μm × 0.25 μm). The temperature program was as follows: initial temperature 40℃, hold for 3 min, then increase to 80℃ at 3℃ / min, hold for 1 min, and finally increase to 250℃ at 10℃ / min, hold for 10 min. The carrier gas was nitrogen at a flow rate of 6.5 mL / min; the septum purge flow rate was 3.0 mL / min; the injection port temperature was 250.0℃, the column oven temperature was 75.0℃, and the injection method was 20:1 split. ③MS conditions: EI ionization source, ion source temperature 230℃, interface temperature 250℃, scan range m / z 35-500, quadrupole temperature 150℃; ionization method: electron impact (EI), electron energy 70 eV; acquisition method: Scan, scan interval 0.30s. Based on the obtained particle flow map, the retention times were compared with the NIST20 and NIST20s spectral libraries to identify the target substances.

[0024] The standard curve for phenylethanol using anhydrous ethanol as the solvent is: y = 1720.5x + 1336.7 (R²) 2 =0.9993)

[0025] like Figure 2 As shown in Figure A-2D, the effects of feed ratio, temperature, loading time, and pH value on encapsulation efficiency are investigated. The results indicate that when the feed ratio is 1:1, the encapsulation efficiency reaches 73.52%, significantly higher than that of other feed ratios. P < 0.05). Using the optimal feed ratio of 1:1, the encapsulation efficiency was measured at different temperatures under the conditions of 4℃ and an encapsulation time of 6 hours. At a reaction temperature of 4℃, the encapsulation efficiency was 67.13%, significantly higher than that at other reaction temperatures. P < 0.05). Using the optimal feed ratio of 1:1, at a temperature of 4℃ and pH=5, after 6 hours of encapsulation (stirring), the encapsulation efficiency was measured at different times. The encapsulation efficiency reached 66.03% at a loading time of 4.5 hours, significantly higher than that at other loading times. P < 0.05). Using the optimal feed ratio of 1:1, at a temperature of 4℃ and an encapsulation time of 6 h, the encapsulation efficiency at different pH values ​​was measured. At pH=6, the encapsulation efficiency reached 49.99%, significantly higher than the encapsulation efficiency at other reaction pH values. P<0.05). Because the experiment could not be conducted below 4℃ due to freezing restrictions, the data were concentrated on only one side of the peak, which did not meet the requirements of symmetrical distribution of response points and fitting of a complete quadratic surface. Therefore, temperature was not used as an optimization factor for the response surface. Instead, the experimental temperature was fixed at 4℃, and other factor variables were optimized based on this.

[0026] Example 3: Optimal Synthesis Process for Phenylacetyl Ethanol@Zn-MOF 1) Response surface methodology optimization experiment Based on single-factor experiments, the process conditions were optimized using response surface methodology. Feed ratio (A), encapsulation time (B), and solution pH (C) were selected as factors, with encapsulation rate as the response value. Response surface experiments were designed according to the Box-Behnken model (Table 1) to determine the optimal preparation parameters for phenylethanol@Zn-MOF.

[0027] Table 1 Response Surface Three-Factor Three-Level

[0028] 2) The experimental scheme and results of the response surface methodology optimization for the preparation of phenylethanol@Zn-MOF are as follows: Using the feed ratio, encapsulation time, and solution pH as factors, 17 sets of experiments were designed, with the center point repeated 5 times. The encapsulation rate was used as the response variable to determine and verify the optimal preparation process (Table 2).

[0029] Table 2 Box-Behnken Experimental Design and Results

[0030] 3) Establishment of regression model and analysis of variance for phenylethanol@Zn-MOF conditions: Regression Model Establishment and Analysis of Variance: Based on the data in Table 2, a predictive model for the preparation process parameters of phenylethanol@Zn-MOF was constructed using multiple quadratic regression analysis. The quadratic multiple regression equations between encapsulation efficiency and various factors are as follows:

[0031] Encapsulation efficiency Y = 71.76 - 7.74A - 3.20B + 1.43C + 4.29AB + 1.43AC - 2.45BC - 8.20A 2 -11.24B 2 -3.88C 2

[0032] As shown in Table 3, the F-value of the model is 12.83. P < 0.001 indicates that the quadratic regression model used in the experiment is highly significant, and the model's lack of fit term is... P =0.0997>0.05, not significant, indicating no lack of fit factors and that the model fits the experiment well. Model determination coefficient R2 =0.9428, indicating that the model fits the actual value well and can predict the theoretical value of phenylethanol@Zn-MOF encapsulation efficiency.

[0033] In the regression model, in the first-order term, factor A has a highly significant effect on the encapsulation rate. P <0.01, Factor B has a significant effect on encapsulation efficiency ( P <0.05). In the quadratic term, A 2 B 2 It has a highly significant impact on encapsulation efficiency. P <0.01). Based on the F-value, the order of significance of the effects of each factor on the encapsulation efficiency is: A> B> C.

[0034] Table 3. Analysis of Variance for Regression Models

[0035] Note: P < 0.05 indicates a significant effect. P < 0.01 indicates a highly significant impact.

[0036] 4) The impact of interactions among various factors on encapsulation efficiency Response surface plots and contour lines were plotted on the interaction terms of feed ratio and encapsulation time (AB), feed ratio and reaction pH (AC), and encapsulation time and reaction pH (BC) in the regression equation to analyze the impact of interactions between different factors on the encapsulation efficiency. The steepness of the response surface plot and the slope of the contour lines both reflect the magnitude of the interactions between factors and indicate the extent to which changes in the two factors affect the encapsulation efficiency. Figure 3 A and Figure 3 As shown in D, the response surface plot is steep with a large slope of the contour lines, but the contour lines are relatively sparse, indicating that there is a certain interaction between the feed ratio and the encapsulation time (AB), but it is not significant. Figure 3 B and Figure 3 As can be seen from E, the response surface plot is relatively flat, the contour lines have a small slope, and the contour lines are relatively sparse, indicating that the interaction between the feed ratio and the reaction pH (AC) is not significant. Figure 3 C and Figure 3 As can be seen from F, the response surface plot is steep and the contour lines have a large slope, but the contour lines are relatively sparse, indicating that there is a certain interaction between the encapsulation time and the reaction pH (BC), but it is not obvious.

[0037] Analysis using Design Expert 13 determined the optimal encapsulation conditions for phenylethanol@Zn-MOF to be a liquid-to-solid ratio of 1:0.738, a time of 4.109 h, and a pH of 6.170, with a predicted encapsulation efficiency of 74.326%. Actual verification under these conditions showed an encapsulation efficiency of 72.63%, close to the predicted result, indicating that the optimization results are effective and reliable.

[0038] Example 4 Performance Characterization of Phenylephethanol@Zn-MOF To determine whether phenylethanol was successfully loaded into the cavity of Zn-MOF, and whether the physicochemical properties of phenylethanol changed before and after loading, the prepared phenylethanol@Zn-MOF was characterized in the following aspects: 1) Scanning Electron Microscopy (SEM): Primarily used to observe the surface morphology of materials. SEM is used to observe the morphology of Zn-MOF, phenethyl alcohol + Zn-MOF physical mixtures, and phenethyl alcohol@Zn-MOF. The sample is first fixed on a silicon wafer, dried, and then secured to the sample stage with conductive adhesive. Platinum is then sputtered onto the wafer, and the surface morphology is observed at 5 kV. Changes in structural morphology before and after inclusion are observed and compared at different magnifications.

[0039] The results show that Zn-MOF exhibits regular long rod-shaped / prismatic crystals with large crystal size, good size uniformity, smooth and clean surface, and only a very small amount of tiny debris attached. Figure 4 A). The surface of phenethyl alcohol + Zn-MOF particles is rough, and some areas show signs of melt adhesion, indicating a physical mixing and interaction between phenethyl alcohol and Zn-MOF. Figure 4 B). The phenylethanol@Zn-MOF crystal structure completely disappeared, presenting as fine particles with no obvious regular morphology, and slight aggregation in some areas. Figure 4 C). The crystal integrity of the material gradually decreases, the particle size continues to shrink, and the dispersibility first deteriorates and then tends to be uniform. This clearly reflects the influence of the introduction method of phenylethanol on the microstructure of Zn-MOF: physical mixing mainly leads to crystal breakage, while loading modification promotes the complete reconstruction of crystals into fine particles.

[0040] 2) Transmission Electron Microscope (TEM): Used to observe the microstructure of materials. The morphology of Zn-MOF, phenethyl alcohol and Zn-MOF physical mixture, and phenethyl alcohol@Zn-MOF are observed by transmission electron microscopy, and the changes in structural morphology before and after encapsulation are compared.

[0041] The results show that Zn-MOF exhibits irregular short rod-shaped or blocky structures with uniform electron density inside the crystal, reflecting its highly ordered crystal structure. Figure 5 A). Physical mixing of phenylethanol and Zn-MOF leads to crystal breakage and size reduction. Figure 5 B), while phenylethanol@Zn-MOF loading modification promotes the reconstruction of the material into uniform spherical particles, forming a core-shell structure (B). Figure 5 C). Loading modification not only changes the morphology of the material, but also improves the uniformity and dispersibility of the particles, which is of great significance for optimizing the material's performance.

[0042] 3) Powder X-ray Diffractometry (PXRD): Used to analyze the crystal structure of materials. When X-rays irradiate a crystal, diffraction occurs. By analyzing the diffraction pattern (peak position, intensity, and width, etc.), information such as the phase composition and lattice constant of the crystal can be determined. Cu Kα rays (λ = 1.5406A0) are used, and data are read in the range of 2θ = 5~40°.

[0043] result Figure 6 As shown, the XRD patterns of the three materials have basically corresponding peak positions, indicating that the introduction of phenylethanol (whether through physical mixing or coating) did not change the main crystal structure of Zn-MOF. The continuous decrease in diffraction peak intensity reflects that the introduction of phenylethanol reduces the crystallinity of Zn-MOF, and the effect of coating modification is greater than that of physical mixing. No new impurity peaks appeared in the spectra, indicating that no new crystal phase was generated during the modification process, and the framework structure of Zn-MOF was preserved.

[0044] 4) Fourier Transform Infrared Spectroscopy (FTIR): Used to analyze the vibrations of characteristic functional groups in samples. Phenylene alcohol, Zn-MOF, a physical mixture of phenylene alcohol and Zn-MOF, and phenylene alcohol@Zn-MOF were prepared into thin films of approximately 1 mm using the KBr pellet method for spectral scanning. A small amount of liquid phenylene sample was dropped onto two KBr windows, pressed into a thin film, and scanned. The wavenumber range was 500–4000 cm⁻¹. -1 , scanned 32 times.

[0045] The results are as follows Figure 7 As shown: Infrared spectra of phenethyl alcohol, Zn-MOF, phenethyl alcohol + Zn-MOF, and phenethyl alcohol@Zn-MOF show that the spectra of the coated and physically mixed substances are similar to those of the parent material Zn-MOF, but significant differences exist. All samples are within the range of 3700–3000 cm⁻¹. -1A broad absorption peak appears (-OH stretching vibration). The -OH peak of free phenylethanol is located at 3308 cm⁻¹. -1 Zn-MOF is located at 3460 cm. -1 The -OH peaks of the two complexes (approximately 3454 cm⁻¹) -1 The fact that the value falls between these two values ​​suggests that there may be hydrogen bonding interactions between phenylethanol and Zn-MOF.

[0046] In 1000–3000 cm -1 At these locations, the ligand benzene ring skeletal vibrational peaks of Zn-MOF (1615, 1437 cm⁻¹) are observed. -1 ) and characteristic peaks of benzene ring / CO (1046 cm⁻¹) -1 The presence of phenylethanol in both complexes directly confirms the successful introduction of phenylethanol. The characteristic peak intensity of phenylethanol@Zn-MOF is slightly weaker than that of the physical mixture, possibly related to the coating structure. (The peak intensity is at 500–1000 cm⁻¹.) -1 At this location, the characteristic peak of the Zn-O bond in Zn-MOF (756 cm⁻¹) -1 The presence of phenylethanol in the complex indicates that the MOF framework structure remains intact; simultaneously, the characteristic peaks of phenylethanol (565, 455 cm⁻¹) are also present. -1 The presence of [a specific substance] further confirms the formation of the complex.

[0047] In summary, the infrared spectra of both complexes simultaneously contain characteristic peaks of both Zn-MOF and phenethyl alcohol, proving that phenethyl alcohol has successfully bound to Zn-MOF. Compared with the parent material and free phenethyl alcohol, the complexes did not exhibit any new characteristic absorption peaks, indicating that no new chemical bonds were introduced during the recombination process, and the original chemical structures of the host and guest molecules remained unchanged. The difference in spectral intensity between physical mixing and coating modification indicates that the two compounds bind in different ways.

[0048] 5) Thermogravimetric Analysis (TGA): Approximately 50 mg of Zn-MOF, a physical mixture of phenethyl alcohol and Zn-MOF, and a dry powder of phenethyl alcohol@Zn-MOF were placed in an alumina crucible and subjected to N2O analysis. 2 Under a specific atmosphere, the percentage of mass loss within the range of 30~800℃ is measured at a heating rate of 10℃ / min to determine the thermal stability of the inclusion compound.

[0049] The results are as follows Figure 8As shown, within the temperature range of 0-100℃, the mass of all three materials decreased slightly, mainly due to the removal of adsorbed water or surface solvents. The weight loss trends of the three materials were almost identical in this stage, indicating that the content of volatile substances adsorbed on the surface was similar. In the temperature ranges of 100-300℃ and 300-500℃, all three materials exhibited significant weight loss peaks. In the first stage between 100-300℃, the weight loss was approximately 70%-80%, with Zn-MOF showing the fastest rate, beginning to decrease significantly around 150℃, and reaching approximately 70% of its original mass at 300℃. The weight loss rates of phenethyl alcohol + Zn-MOF and phenethyl alcohol@Zn-MOF were more gradual, with the mass ratio remaining at approximately 78%–80% at 300℃. The differences in this stage mainly stemmed from the initial decomposition of the Zn-MOF skeleton, while the introduction of phenethyl alcohol provided some protection to the skeleton. At higher temperatures, all three materials undergo a second significant weight loss. Zn-MOF enters a rapid weight loss phase after 400℃, and its mass ratio drops to approximately 60% at 500℃. The weight loss rate of phenethyl alcohol + Zn-MOF and phenethyl alcohol@Zn-MOF only accelerates significantly after 400℃, exhibiting better thermal stability. This indicates that coating or mixing with phenethyl alcohol can delay the deep decomposition of the Zn-MOF skeleton, with coating modification showing a slightly better protective effect. In the high-temperature range of 300-500℃, the mass of Zn-MOF continues to decrease rapidly, with its mass ratio only about 35% at 700℃. The mass decrease of phenethyl alcohol + Zn-MOF and phenethyl alcohol@Zn-MOF slows down, and their mass ratio remains around 45% at 700℃. The difference in residual mass at this stage suggests that the introduction of phenethyl alcohol not only improves thermal stability but may also alter the composition of the final pyrolysis products.

[0050] The introduction of phenethyl alcohol (whether through physical mixing or coating modification) significantly improves the thermal stability of Zn-MOFs and slows down their decomposition process. Coating modification shows a slightly better thermal stabilization effect than physical mixing. The thermal decomposition of all three materials exhibits multi-stage weight loss characteristics, reflecting the decomposition of different components (adsorbed solvent, MOF framework, and phenethyl alcohol) at different temperatures. Thermal stability is a crucial driving force for the development of Zn-MOF materials; therefore, Zn-MOFs have potential value in improving the thermal stability of organic compounds.

[0051] In summary, phenethyl alcohol@Zn-MOF and phenethyl alcohol + Zn-MOF exhibit significantly better thermal stability than pure Zn-MOF, with higher residual mass across the entire temperature range. This indicates that the loading or mixing of phenethyl alcohol effectively delays the thermal decomposition of the Zn-MOF framework. The high overlap between the curves of phenethyl alcohol@Zn-MOF and phenethyl alcohol + Zn-MOF suggests that phenethyl alcohol exists primarily in a physical encapsulation or adsorption state in the composite material, rather than undergoing strong chemical bonding with Zn-MOF. The slow weight loss of phenethyl alcohol at low temperatures (<200℃) demonstrates that the Zn-MOF support can effectively delay the thermal release of phenethyl alcohol, showcasing its potential as a controlled-release carrier.

[0052] Example 5: Phenylethanol release from phenylethanol@Zn-MOF To plot the standard curve of phenylethanol content in Zn-MOF: Prepare phenylethanol / n-hexane solutions of 0.1, 0.15, 0.2, 0.25, 0.3, and 0.35 mg / mL, and inject 1 μL of each standard solution. Plot the standard curve with the peak area of ​​phenylethanol as the ordinate and the concentration of phenylethanol as the abscissa (1). To calculate the standard curve of free phenylethanol content: Prepare phenylethanol / n-hexane solutions of 8, 9, 10, 11, 12, and 13 mg / mL, and inject 1 μL of each standard solution. Plot the standard curve with the peak area of ​​phenylethanol as the ordinate and the concentration of phenylethanol as the abscissa (2).

[0053] Determination of sustained-release properties of phenylethanol@Zn-MOF: The prepared phenylethanol@Zn-MOF was placed in a 20 mL headspace vial and sealed. A solid-phase microextraction probe (57328-U) was inserted into the headspace vial, and phenylethanol released at 0, 2, 6, 8, and 12 h, and 1, 2, 4, 6, and 8 days were collected at 25 °C. The probe adsorption time was 30 min for each time. An equal volume of phenylethanol was used as a control. The release rate of phenylethanol@Zn-MOF was calculated according to the following formula, and a release curve was plotted with time on the x-axis and release rate on the y-axis.

[0054]

[0055] GC conditions: Instrument model: Shimadzu GCMS-QP2016, HP-5MS column (30.0m × 0.25mm × 0.25μm). Temperature program: initial temperature 75℃, then increased to 230℃ at 10℃ / min, held for 10 min. Carrier gas: nitrogen, flow rate 0.84 mL / min; septum purge flow rate: 3.0 mL / min; injection port temperature: 250.0℃, column oven temperature: 75.0℃, injection mode: 20:1 split. MS conditions: same as in Example 2.

[0056] The results show that the standard curve (1) is: y = 397817x + 464.55 (R2 =0.9946); Standard curve (2): y=297040x+ 234965 (R 2 = 0.9936)

[0057] like Figure 9 As shown, after 8 days (192 hours), the release rate of phenylethanol showed that the release rate of free phenylethanol reached 82.72%, while the release rate of phenylethanol@Zn-MOF was 1.78%. The release rate of phenylethanol was plotted on the ordinate, and the release time on the abscissa, resulting in the following equation for the release of free phenylethanol: y = 0.1456x + 60.602 (R²). 2 =0.7432), it takes approximately 12 days for the free phenylethanol release rate to reach 100%. The average release rate of phenylethanol@Zn-MOF is 0.024% / h, and after 12 days, the phenylethanol release rate of this composite material is 6.36%. It is predicted that after two months, the phenylethanol release rate of this composite material will be 34.56%, indicating that Zn-MOF encapsulation of phenylethanol can delay the release of phenylethanol.

[0058] The phenylethanol@Zn-MOF prepared by the method described in this invention has an encapsulation efficiency of over 72%, significantly improving the phenylethanol loading efficiency. At the same time, the Zn-MOF support has a complete structure, which can effectively delay the volatilization of phenylethanol, providing a material basis for its controlled release applications in food, medicine, agriculture and other fields.

[0059] Example 6: Application of the composite material of the present invention

[0060] 6.1 Application of composite materials in tomato cultivation Test location: Pingtan Township, Yuanmou County, Chuxiong Yi Autonomous Prefecture, Yunnan Province (25°45′58″N, 101°46′15″E, altitude 1175 m).

[0061] Experimental Design: The experimental material was the 6213 pink-fruited tomato. A completely randomized block design was used, with a total of 5 treatments: pure chemical agent (CK), 10 μL / L phenylethanol, Zn-MOF, and phenylethanol@Zn-MOF (containing 10 μL / L phenylethanol). Each treatment was replicated 3 times, with each replicate containing 50 tomato seedlings. The plant spacing was 50 cm between plants and 100 cm between rows, forming one experimental plot. There were a total of 3 plots in the experiment. The plot area was 25 m × 20 m, with a 1 m wide protective row around the perimeter. The pesticide was applied every 15 days for a total of 5 applications, continuing until harvest.

[0062] Growth index determination: In accordance with the "Tomato Germplasm Resource Description Specification and Data Standard", 10 plants were investigated in each plot when the tomatoes were 90 days old, and the stem diameter and chlorophyll content of tomatoes in the experimental plot of each plot were measured. Finally, when measuring the yield, 10 plants were randomly selected from each plot to investigate the number of fruits per plant and the weight of the fruits.

[0063] Disease survey: A disease survey was conducted after the fifth pesticide treatment. Ten plants were surveyed in each plot to analyze the incidence of early blight, viral diseases, etc., and to calculate the disease index. The following survey methods were used: Early blight investigation method: The severity of early blight in tomatoes is investigated using a 6-level grading system: 0, 1, 3, 5, 7, and 9. The specific standards are as follows: Level 0: No visible lesions on the plant or leaves, and normal growth; Level 1: Lesions cover less than 5% of the leaf area, or only a few leaves show scattered lesions; Level 3: Lesions cover 6%–15% of the leaf area, or less than 1 / 4 of the leaves on the entire plant show lesions; Level 5: Lesions cover 16%–25% of the leaf area, or 1 / 4–1 / 2 of the leaves on the entire plant show lesions; Level 7: Lesions cover 26%–50% of the leaf area, or 1 / 2–3 / 4 of the leaves on the entire plant show lesions; Level 9: Lesions cover more than 50% of the leaf area, or more than 3 / 4 of the leaves on the entire plant are affected, with some leaves withering or falling off. During the survey, 10 representative tomato plants were randomly selected from each plot. Two leaves from the upper, middle and lower parts of each plant were examined, and the number of plants with each disease level was recorded.

[0064] Methods for investigating viral diseases in tomatoes: The severity of tomato viral diseases was assessed using a six-level grading system: 0, 1, 3, 5, 7, and 9. The specific standards are as follows: Level 0: No visible symptoms, normal growth; Level 1: Clear veins in the heart leaves or slight mosaic pattern, no significant stunting; Level 3: Obvious mosaic or mottling on the leaves, slight stunting, not affecting normal flowering and fruiting; Level 5: Severe mosaic or wrinkled leaves, narrowed or deformed leaves, moderate stunting, reduced fruit quantity; Level 7: Severely deformed or fern-like leaves, severely stunted, few fruits and small fruits; Level 9: Extremely stunted or necrotic plants, even complete wilting and death. During the investigation, 10 representative tomato plants were randomly selected from each plot, and the symptoms were observed and recorded for each disease level.

[0065] Incidence rate = (Number of diseased leaves / Total number of leaves surveyed) × 100% Disease index = 100 × ∑ (number of diseased leaves at each level × representative value at each level) / (total number of leaves surveyed × highest representative value) Yield Measurement: Yield measurement was conducted during the tomato fruit ripening period. Theoretical yield was estimated based on planting density, number of fruits per plant, and average fruit weight. A fixed-plant yield measurement method was used, calculating the tomato plot yield based on the number of fruits per plant, fruit weight, and the number of tomato plants in the plot: Tomato yield per acre (kg / acre) = Number of fruits per plant × Fruit weight per fruit (g / fruit) × Planting density (plants / acre). Planting density was calculated based on the actual plant-row spacing: Planting density = 666.67 ÷ [Plant spacing (m) × Row spacing (m)]

[0066] Quality index determination: 500g of tomato fruit were randomly selected from each plot, brought back to the laboratory in ice packs for preservation, and the tomato quality indexes were determined. These mainly included: soluble solids content (refractometer method, NY / T2637—2014), lycopene determination (ultraviolet-spectrophotometry), and vitamin C content (titration method).

[0067] The specific growth conditions of tomatoes in the field are as follows: Figure 10 As shown, the results indicated that compared with the control (CK), both phenylethanol and phenylethanol@Zn-MOF treatments increased the stem diameter and chlorophyll content of tomatoes, but the difference was not statistically significant. P >0.05); the stem diameter of phenylethanol@Zn-MOF increased from 13.89 mm to 14.27 mm compared with CK, an increase of 2.74%. The chlorophyll content increased from 31.73 to 33.93 compared with CK, an increase of 6.93%.

[0068] Field tomato yield Figure 11 As shown, compared with the control (CK), spraying with phenylethanol@Zn-MOF effectively promoted tomato yield, increasing the average yield per mu (667 square meters) from 7012.07 kg / mu to 7433.09 kg / mu, an increase of 421.02 kg / mu, or approximately 6.00%. This demonstrates that spraying with phenylethanol@Zn-MOF effectively promotes tomato plant yield.

[0069] The following are the field tomato quality tests: Figure 12 As shown, compared with phenylethanol, the soluble solids content of tomatoes increased from 4.66% to 4.82%, an increase of 3.43%; lycopene increased from 16.81 mg / 100g to 24.31 mg / 100g, an increase of 44.62%; and vitamin C increased from 1.94 mg / 100g to 2.75 mg / 100g, an increase of 41.75%.

[0070] Rice disease situation in the field Figure 13As shown, compared with the control (CK), phenylethanol@Zn-MOF treatment reduced the incidence and disease index of early blight in tomatoes by 40.00% and 29.55%, respectively; and reduced the incidence and disease index of viral diseases in tomatoes by 24.99% and 31.82%, respectively. The results indicate that phenylethanol@Zn-MOF can alleviate the occurrence of early blight and viral diseases in tomatoes.

[0071] 6.2 Application of composite materials in rice cultivation Test location: Zhongheying Town, Kaiyuan City, Honghe Prefecture, Yunnan Province (23°46′57″N, 103°38′17″E, altitude 1948m).

[0072] Experimental Design: Dianheyou 615 was selected as the experimental material. A completely randomized block design was adopted, with a total of 4 treatments: pure chemical reagent (CK), 10 μL / L phenylethanol, Zn-MOF, and phenylethanol@Zn-MOF (containing 10 μL / L phenylethanol). The total experimental area was 400 m². 2 Each treatment was repeated 3 times. Rice fields with similar growth and flat land were selected and divided into 4 m × 5 m plots. Each plot had a 1 m protective row. The pesticide was applied once every 15 days for a total of 5 applications until harvest.

[0073] Growth index determination: Sampling was conducted at the rice maturity stage, with 15 plants surveyed in each plot. The plant height, fresh weight, and dry weight of rice in the experimental plot of each plot were measured. Finally, during the yield measurement, 15 plants were randomly selected from each plot to investigate the thousand-grain weight, effective panicle number, number of grains per panicle, seed setting rate, theoretical yield, and actual yield.

[0074] Disease survey: A disease survey was conducted after the fifth pesticide treatment. Fifteen plants were surveyed in each plot to analyze the incidence and disease index of rice leaf blast and sesame leaf spot. The following survey methods were used:

[0075] Leaf blast disease investigation method: Grading standard: Grade 0, no disease; Grade 1: less than 5% loss per ear, or individual branches are diseased; Grade 2: 5.1%~20% loss per ear, or one-third of branches are diseased; Grade 3: 20.1%~50% loss per ear, or neck or main axis are diseased, with a small portion of empty grains; Grade 4: 50.1%~70% loss per ear, or neck is diseased, with most empty grains; Grade 5: more than 70.1% loss per ear, or neck disease causes white ears.

[0076] Methods for investigating sesame leaf spot disease: Grading standards: Grade 0: No disease; Grade 1: Diseased area less than 1% of leaf area; Grade 3: Diseased area 2% to 5% of leaf area; Grade 5: Diseased area 6% to 15% of leaf area; Grade 7: Diseased area 16% to 25% of leaf area; Grade 9: Diseased area more than 25% of leaf area.

[0077] Incidence rate = (Number of diseased leaves / Total number of leaves surveyed) × 100% Disease index = 100 × ∑ (number of diseased leaves at each level × representative value at each level) / (total number of leaves surveyed × highest representative value) Yield determination: Theoretical yield: Rice yield per mu (kg / mu) = Effective panicles (10,000 / mu) × Number of grains per panicle × Seed setting rate × 1000-grain weight (g) × 10 -6 Actual yield: After the rice matures, each plot is harvested separately, and the actual yield is measured using an electronic scale.

[0078] The specific growth conditions of rice in the field are as follows: Figure 14 As shown: Compared with the control (CK), phenylethanol@Zn-MOF significantly increased plant height, fresh weight, and dry weight. P < 0.05), the plant height of phenylethanol@Zn-MOF was 120.4 cm / plant, an increase of 8.46% compared with CK. The fresh weight and dry weight of phenylethanol@Zn-MOF were 57.94 g / plant and 29.61 g / plant, respectively, an increase of 29.56% and 39.07% compared with CK.

[0079] Rice yield at maturity in the field Figure 15 As shown: the thousand-grain weight and seed setting rate of each treatment were not significantly different from those of the control (CK). P >0.05), the theoretical yield of phenylethanol@Zn-MOF was 842.08 kg / mu, which was significantly increased by 6.03% compared with the theoretical yield of CK 794.13 kg / mu. P < 0.05); The actual yield of phenylethanol@Zn-MOF was 487.43 kg / mu, which was significantly increased by 15.3% compared with the actual yield of CK (422.72 kg / mu). P < 0.05).

[0080] Rice disease situation in the field Figure 16 As shown, compared with the control (CK), phenylethanol@Zn-MOF treatment reduced the incidence and disease index of rice leaf blast by 42.59% and 54.02%, respectively; and reduced the incidence and disease index of sesame leaf spot by 54.78% and 52.44%, respectively. The results indicate that phenylethanol@Zn-MOF can alleviate the occurrence of rice leaf blast and sesame leaf spot.

Claims

1. A Zn-MOF-loaded phenylethanol composite material, characterized in that: The Zn-MOF-loaded phenylethanol composite material uses Zn-MOF as a carrier skeleton, and phenylethanol is stably loaded into the pores or surface of Zn-MOF to form a core-shell type or pore-filled type sustained-release composite material; the Zn-MOF is a white rectangular powder crystal synthesized by hydrothermal reaction of zinc acetate and 1,3,5-tribenzoic acid.

2. A method for preparing a Zn-MOF-loaded phenylethanol composite material, comprising the following steps: Phenylacetyl alcohol and Zn-MOF were mixed evenly at a ratio of 1:0.5-2.5, and the pH was adjusted to 4-8. The mixture was stirred continuously with a magnetic stirrer at 4-35℃ for 3-9 h, and then left to stand for more than 24 h. The mixture was then centrifuged at 10000 r / min for 10 min at 4℃, washed with anhydrous ethanol, and the supernatant was collected and filtered through a filter with a pore size of 0.45 µm to obtain the Zn-MOF-loaded phenylacetyl alcohol composite material.

3. The method for preparing Zn-MOF-loaded phenylethanol composite material as described in claim 2, characterized in that: The preparation method of Zn-MOF is as follows: Weigh 9.170g of zinc acetate, add 84.4 mL of pure water, and dissolve and mix well to obtain solution A; weigh 5.25g of 1,3,5-tribenzoic acid, add 83.4 mL of anhydrous ethanol, and dissolve and mix well to obtain solution B; add solution B to solution A, sonicate and mix for 10 min, place in a high-pressure reactor lined with polytetrafluoroethylene, place the high-pressure reactor in an oven, react at 120℃ for 10 h, close the oven, and allow the high-pressure reactor to cool to room temperature. After removal, centrifuge and wash with ethanol and pure water at 4℃, 5000 r / min for 10 min, and dry under vacuum at 60℃ to obtain white rectangular powder crystals.

4. The method for preparing Zn-MOF-loaded phenylethanol composite material as described in claim 2, characterized in that: The feed ratio of phenylethanol to Zn-MOF is 1:0.5-1.

5.

5. The method for preparing Zn-MOF-loaded phenylethanol composite material as described in claim 2, characterized in that: The pH value is 5-7.

6. The method for preparing Zn-MOF-loaded phenylethanol composite material as described in claim 2, characterized in that: The stirring time is 3-6 hours.

7. The application of the Zn-MOF-loaded phenylethanol composite material as described in claim 1 or the method described in any one of claims 2-6 in promoting growth, increasing yield and inhibiting diseases in tomatoes and rice.

8. The application as described in claim 7, characterized in that: The diseases mentioned are early blight of tomato, tomato viral disease, rice leaf spot, and rice leaf blast.

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