A film doped material with light conversion function and its biodegradable agricultural light conversion film

Abstract

This invention belongs to the field of chemical technology, specifically relating to a light-converting thin-film doped material and its biodegradable agricultural light-converting film. The light-converting thin-film doped material has the structure shown in formula (I): The light-converting thin-film doped material of formula (I) provided by this invention has high absorbance. It can absorb the ultraviolet and blue-green light portions of natural light that are not utilized by plants through small organic molecules, and emit red fluorescence required for photosynthesis. This protects the plant from ultraviolet radiation and regulates crop growth through natural "supplementary lighting." It also has excellent compatibility with environmentally friendly plastics such as polylactic acid, and can be dispersed and doped in monomolecular form without altering the original properties of the plastic film, thus enabling its application in the production of light-modulating agricultural films.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically, it relates to a thin film doped material with light conversion function and its biodegradable agricultural light conversion film. Background Technology

[0002] In modern agricultural production, widely used plastic greenhouse films regulate environmental factors such as temperature, humidity, and carbon dioxide concentration during crop growth, thereby ensuring high-quality and high-yield agricultural products. However, due to the non-degradable nature of discarded plastic greenhouse films, they cause some environmental damage. Developing and producing new greenhouse film materials based on environmentally friendly and biodegradable plastics has become an urgent problem to be solved, especially functional light-regulating films.

[0003] During plant growth, photosynthesis utilizes solar energy to convert carbon dioxide and water into nutrients. In this process, chlorophyll, responsible for converting solar energy, tends to absorb the blue and red light components of sunlight, while absorbing less or no ultraviolet and blue-green light. Strong ultraviolet light can even damage plants. Therefore, how to convert the ultraviolet and blue-green light components of natural light that are not utilized by plants into red fluorescence needed for photosynthesis, thereby regulating the light received inside greenhouses and promoting plant growth, has become an urgent problem to be solved.

[0004] CN114085195A discloses a biodegradable thin film material with light-converting properties, its preparation method, and its film doping material. This film doping material can absorb the ultraviolet and green light portions of natural light that are not utilized by plants through small organic molecules, and emit red fluorescence required for photosynthesis. This not only protects the plant from ultraviolet radiation but also regulates crop growth through natural "supplementary lighting."

[0005] However, different plants have different light requirements during their growth. Therefore, it is necessary to provide a new type of agricultural light-converting film with different absorption and emission spectra and simpler molecular synthesis to meet the light requirements of different plant growth processes. Summary of the Invention

[0006] The purpose of this invention is to provide a thin-film doped material with light-converting function and its biodegradable agricultural light-converting film. It can not only convert the ultraviolet and blue-green light portions of natural light that are not used by plants into red fluorescence required for photosynthesis, thereby achieving the purpose of regulating the light received inside the greenhouse and promoting plant growth, but also has different absorption and emission spectra compared with the prior art, which can be used to adapt to the light requirements of different plant growth processes.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A thin-film doped material with optical conversion function, wherein the material has a structure as shown in formula (I):

[0009]

[0010] The inventors have discovered that thin films prepared by doping polylactic acid with small organic molecules possessing specific absorption and emission wavelengths at low concentrations can convert the ultraviolet and blue-green light portions of natural light, which are not utilized by plants, into red fluorescence required for photosynthesis. This can regulate the light received inside greenhouses and promote plant growth. Based on this, and building upon extensive research, the inventors provide a novel thin-film doped material with light-conversion function, as shown in formula (I) above. Compared with existing technologies, this thin-film doped material has different absorption and emission spectra. It can absorb ultraviolet and blue-green light from sunlight, adapting to the light requirements of different plant growth processes and efficiently converting it into red fluorescence to supplement light for plants, thus assisting plant growth and ultimately increasing yield.

[0011] This invention also provides a method for preparing the above-mentioned thin film doped material with light conversion function, specifically,

[0012] The synthetic route of this preparation method is as follows:

[0013]

[0014] The preparation method includes the following steps:

[0015] Step 1: Weigh 1-(4-cyanomethylphenyl)-1,2,2-tristyrene and Lewis base into a two-necked flask. Replace the air in the flask with nitrogen, add an alcohol solvent, and heat to react. Add benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde under a nitrogen atmosphere to continue the reaction.

[0016] Step 2: After the reaction is completed, the reaction solution is cooled and poured into a large amount of water. Dichloromethane is used for extraction, the organic phases are combined, anhydrous magnesium sulfate is added for drying, and the residue obtained by filtration and vacuum concentration is separated by silica gel column chromatography. After solvent is evaporated under vacuum, a red powder is obtained, which is the thin film doped material with light conversion function shown in formula (I).

[0017] The preparation method provided by this invention uses benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and 1-(4-cyanomethylphenyl)-1,2,2-tristyrene as raw materials through a one-step Knoevenagel condensation reaction. Not only is the synthesis simple, but the resulting film doped material with light-converting function, as shown in formula (I), has high absorbance. It can absorb the ultraviolet and blue-green light portions of natural light that are not utilized by plants through small organic molecules, and emit red fluorescence required for photosynthesis. This can protect plants from ultraviolet damage and regulate crop growth through natural "supplementary light". It also has very good compatibility with environmentally friendly plastics such as polylactic acid, and can be dispersed and doped in the form of monomolecules without changing the original physical properties of the plastic film, thus being applied to the production of light-modulating agricultural films.

[0018] In the above preparation method, in step 1, the ratio of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene: Lewis base: alcohol solvent: benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde is 1.0 mmol: 1.0-1.5 mmol: 20-40 mL: 0.4-0.5 mmol.

[0019] In the above preparation method, in step 1, the heating reaction is carried out at 40-60°C for 25-35 minutes, and the reaction continues for 8-16 hours.

[0020] In the above preparation method, in step 2, the eluent used for silica gel column chromatography is a mixture of chloroform and petroleum ether in a volume ratio of 1:1.

[0021] In the above preparation method, the Lewis base mentioned in step 1 is any one of the Lewis bases formed by lithium, sodium, and potassium ions, namely methanol-based, ethanol-based, or tert-butanol-based.

[0022] In the above preparation method, the alcohol solvent mentioned in step 1 is any one of small molecule alcohols such as methanol, ethanol, tert-butanol or ethylene glycol.

[0023] The present invention also provides a biodegradable agricultural light-converting film, wherein the biodegradable agricultural light-converting film is prepared by mixing the above-mentioned light-converting film doping material with polylactic acid.

[0024] The present invention further provides a method for preparing the biodegradable agricultural light-converting film, wherein the preparation method is as follows:

[0025] Place the light-converting film doped material and polylactic acid particles as shown in formula (I) into a clean small beaker, add an organic solvent, heat and stir until completely dissolved to form a uniform transparent solution, continue heating and stirring to gradually increase the viscosity of the solution, and immediately pour the solution onto a clean glass plate after stopping heating. Use a perforated mold to control the shape, area and thickness of the film, allow the solvent to evaporate completely in a natural environment, and remove it after it dries to form a film. Use a vacuum oven to remove the residual solvent to obtain the biodegradable agricultural light-converting film.

[0026] In the above preparation method, the mass ratio of the thin film doped material to the polylactic acid particles is 1g:100-10000g, and the mass-volume ratio of the polylactic acid particles to the organic solvent is 1g:10-50mL.

[0027] In the above preparation method, the viscosity of the solution after continuous heating and stirring is 50-150 cP.

[0028] In the above preparation method, the heating temperature is 40-90℃; the pressure of the vacuum oven is -40 to -80 kPa, and the temperature is 40-80℃.

[0029] In the above preparation method, the organic solvent for the thin film doped material with light conversion function and polylactic acid particles shown in the dissolution formula (I) is one of dichloromethane, trichloromethane or tetrahydrofuran.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The biodegradable agricultural light-converting film material provided by the present invention has low doping concentration, uniform dispersion, high absorbance and high luminous efficiency, and does not damage the original physical properties of the polymer.

[0032] (2) The biodegradable agricultural light-converting film material provided by the present invention is a fluorescent film material. It has a very strong absorption capacity for ultraviolet light and blue-green light in sunlight (the part that is usually not absorbed by plant chlorophyll), and can emit strong red fluorescence (the part that is usually utilized by plant photosynthesis). It can be used in the cultivation and production of various agricultural products. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is the fluorescence spectrum of a 1% mass concentration polylactic acid-doped thin film (approximately 0.1 mm thick) used in this invention;

[0035] Figure 2 This is the UV-Vis absorption spectrum of a polylactic acid-doped thin film (approximately 0.1 mm thick) with a mass concentration of 0.1% in this invention.

[0036] Figure 3 This is the fluorescence spectrum of a polylactic acid-doped thin film (approximately 0.1 mm thick) with a mass concentration of 0.1% in this invention. Detailed Implementation

[0037] The following are specific embodiments of the present invention. These embodiments are intended to further describe the present invention and are not intended to limit the present invention.

[0038] Example 1

[0039] I. Preparation of thin film doped materials with light conversion function as shown in formula (I)

[0040] The synthetic route is as follows:

[0041]

[0042] The preparation method includes the following steps:

[0043] Step 1: Weigh 1.0 mmol (0.371 g) of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene and 1.0 mmol (0.054 g) of sodium methoxide into a two-necked flask. After replacing the air in the flask with nitrogen, add 20 mL of methanol using a disposable syringe and heat the mixture at 40 °C for 30 minutes. Then, under a nitrogen atmosphere, add 0.5 mmol (0.096 g) of benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and continue the reaction for 8 hours.

[0044] Step 2: After the reaction is complete, the reaction solution is cooled and poured into a large amount of water. Extraction is performed using dichloromethane. The organic phases are combined, and anhydrous magnesium sulfate is added for drying. The residue obtained by filtration and vacuum concentration is then subjected to silica gel column chromatography with dichloromethane:petroleum ether as the eluent (1:1). After rotary evaporation of the solvent under reduced pressure, a red powder is obtained, namely 0.312 g of the optically active thin film doped material shown in formula (I), with a total yield of 69.4%.

[0045] II. Preparation of Biodegradable Agricultural Light-Converting Thin Film Materials

[0046] Weigh 0.01 g of the light-converting film doped material (as shown in formula (I)) and 0.99 g of polylactic acid particles obtained in step one into a clean small beaker. Add 30 mL of dichloromethane and heat and stir at 50 °C until the light-converting film doped material and polylactic acid particles shown in formula (I) are completely dissolved to form a uniform and transparent solution. Continue heating and stirring until the viscosity of the solution gradually increases to about 80 cP. After stopping heating, immediately pour the solution onto a pre-prepared clean glass plate. Use a perforated mold to control the shape, area, and thickness of the film. Allow the solvent to evaporate completely under natural conditions. After drying and forming a film, remove the film and dry it in a vacuum oven at -40 kPa and 60 °C for 2 hours to remove residual solvent, obtaining a 1.0% mass concentration polylactic acid film doped with formula (I), which is the biodegradable agricultural light-converting film. This film can be stretched, bent, and sheared, and has strong fluorescence.

[0047] Example 2

[0048] I. Preparation of thin film doped materials with light conversion function as shown in formula (I)

[0049] The synthesis route is the same as in Example 1.

[0050] The preparation method includes the following steps:

[0051] Step 1: Weigh 2.0 mmol (0.743 g) of 1-(4-cyanomethylphenyl)-1,2,2-tristyrene and 2.2 mmol (0.150 g) of sodium ethoxide into a two-necked flask. After replacing the air in the flask with nitrogen, add 30 mL of ethylene glycol using a disposable syringe and heat the mixture at 50 °C for 30 minutes. Then, under a nitrogen atmosphere, add 0.9 mmol (0.173 g) of benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and continue the reaction for 12 hours.

[0052] Step 2: After the reaction is complete, the reaction solution is cooled and poured into a large amount of water. Extraction is performed using dichloromethane. The organic phases are combined, and anhydrous magnesium sulfate is added for drying. The residue obtained by filtration and vacuum concentration is then subjected to silica gel column chromatography with dichloromethane:petroleum ether as the eluent (1:1). After rotary evaporation of the solvent under reduced pressure, a red powder is obtained, namely 0.461 g of the optically active thin film doped material shown in formula (I), with a total yield of 56.9%.

[0053] II. Preparation of Biodegradable Agricultural Light-Converting Thin Film Materials

[0054] Weigh 0.01 g of the light-converting film doped material and 9.99 g of polylactic acid particles (PLA particles) as shown in formula (I) obtained in step one into a clean small beaker. Add 200 mL of dichloromethane and heat and stir at 50 °C until the light-converting film doped material and PLA particles shown in formula (I) are completely dissolved to form a uniform and transparent solution. Continue heating and stirring to gradually increase the viscosity of the solution to about 100 cP. After stopping heating, immediately pour the solution onto a clean glass plate that has been prepared in advance. Use a cutout mold to control the shape, area and thickness of the film. Allow the solvent to evaporate completely under natural conditions. After it dries and forms a film, remove it and dry it in a vacuum oven at -50 kPa and 50 °C for 2 hours to remove residual solvent, and obtain a 0.1% mass concentration PLA-doped film of formula (I), which is the biodegradable agricultural light-converting film.

[0055] Example 3

[0056] I. Preparation of thin film doped materials with light conversion function as shown in formula (I)

[0057] The synthesis route is the same as in Example 1.

[0058] The preparation method includes the following steps:

[0059] Step 1: Weigh 1.0 mmol (0.371 g) of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene and 1.1 mmol (0.123 g) of potassium tert-butoxide into a two-necked flask. After replacing the air in the flask with nitrogen, add 30 mL of ethanol using a disposable syringe and heat the mixture at 40 °C for 30 minutes. Then, under a nitrogen atmosphere, add 0.4 mmol (0.077 g) of benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and continue the reaction for 8 hours.

[0060] Step 2: After the reaction is complete, the reaction solution is cooled and poured into a large amount of water. Extraction is performed using dichloromethane. The organic phases are combined, and anhydrous magnesium sulfate is added for drying. The residue obtained by filtration and vacuum concentration is then subjected to silica gel column chromatography with dichloromethane:petroleum ether as the eluent (1:1). After rotary evaporation of the solvent under reduced pressure, a red powder is obtained, namely 0.285 g of the optically active film doped material shown in formula (I), with a total yield of 79.2%.

[0061] II. Preparation of Biodegradable Agricultural Light-Converting Thin Film Materials

[0062] Weigh 0.05 g of the light-converting film doped material (as shown in formula (I)) obtained in step one and 9.95 g of polylactic acid particles into a clean small beaker. Add 80 mL of chloroform and heat and stir at 60 °C until the light-converting film doped material and polylactic acid particles shown in formula (I) are completely dissolved to form a uniform and transparent solution. Continue heating and stirring until the viscosity of the solution gradually increases to about 110 cP. After stopping heating, immediately pour the solution onto a pre-prepared clean glass plate. Use a perforated mold to control the shape, area, and thickness of the film. Allow the solvent to evaporate completely under natural conditions. After drying and forming a film, remove the film and dry it in a vacuum oven at -60 kPa and 40 °C for 2 hours to remove residual solvent, obtaining a 0.5% mass concentration polylactic acid film doped with formula (I), which is the biodegradable agricultural light-converting film. This film can be stretched, bent, and sheared, and has strong fluorescence.

[0063] Example 4

[0064] I. Preparation of thin film doped materials with light conversion function as shown in formula (I)

[0065] The synthesis route is the same as in Example 1.

[0066] The preparation method includes the following steps:

[0067] Step 1: Weigh 1.5 mmol (0.557 g) of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene and 1.8 mmol (0.093 g) of lithium ethoxide into a two-necked flask. After replacing the air in the flask with nitrogen, add 50 mL of methanol using a disposable syringe and heat the mixture at 60 °C for 30 minutes. Then, under a nitrogen atmosphere, add 0.7 mmol (0.134 g) of benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and continue the reaction for 16 hours.

[0068] Step 2: After the reaction is complete, the reaction solution is cooled and poured into a large amount of water. Extraction is performed using dichloromethane. The organic phases are combined, and anhydrous magnesium sulfate is added for drying. The residue obtained by filtration and vacuum concentration is then subjected to silica gel column chromatography with dichloromethane:petroleum ether as the eluent (1:1). After rotary evaporation of the solvent under reduced pressure, a red powder is obtained, namely 0.412 g of the optically active thin film doped material shown in formula (I), with a total yield of 65.5%.

[0069] II. Preparation of Biodegradable Agricultural Light-Converting Thin Film Materials

[0070] Weigh 0.01 g of the light-converting film doped material of formula (I) obtained in step one and 99.99 g of polylactic acid particles into a clean small beaker. Add 1000 mL of tetrahydrofuran and heat and stir at 90 °C until the light-converting film doped material of formula (I) and polylactic acid particles are completely dissolved to form a uniform and transparent solution. Continue heating and stirring to gradually increase the viscosity of the solution to about 60 cP. After stopping heating, immediately pour the solution onto a clean glass plate that has been prepared in advance. Use a cutout mold to control the shape, area and thickness of the film. Allow the solvent to evaporate completely under natural conditions. After it dries and forms a film, remove it and dry it in a vacuum oven at -80 kPa and 50 °C for 2 hours to remove residual solvent, and obtain a polylactic acid film of formula (I) with a mass concentration of 0.01%, which is the biodegradable agricultural light-converting film.

[0071] Example 5

[0072] I. Preparation of thin film doped materials with light conversion function as shown in formula (I)

[0073] The synthesis route is the same as in Example 1.

[0074] The preparation method includes the following steps:

[0075] Step 1: Weigh 5.0 mmol (1.857 g) of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene and 6.0 mmol (0.421 g) of potassium methoxide into a two-necked flask. After replacing the air in the flask with nitrogen, add 100 mL of tert-butanol using a disposable syringe and heat the mixture at 40 °C for 30 minutes. Then, under a nitrogen atmosphere, add 2.0 mmol (1.798 g) of benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde and continue the reaction for 10 hours.

[0076] Step 2: After the reaction is complete, the reaction solution is cooled and poured into a large amount of water. Extraction is performed using dichloromethane. The organic phases are combined, and anhydrous magnesium sulfate is added for drying. The residue obtained after filtration and vacuum concentration is then subjected to silica gel column chromatography with dichloromethane:petroleum ether as the eluent (1:1). After rotary evaporation of the solvent under reduced pressure, a red powder is obtained, namely 1.531 g of the optically active thin film doped material shown in formula (I), with a total yield of 85.1%.

[0077] II. Preparation of Biodegradable Agricultural Light-Converting Thin Film Materials

[0078] Weigh 0.05 g of the light-converting film doped material and 99.95 g of polylactic acid particles (PLA particles) as shown in formula (I) obtained in step one into a clean small beaker. Add 1000 mL of dichloromethane and heat and stir at 60 °C until the light-converting film doped material and PLA particles shown in formula (I) are completely dissolved to form a uniform and transparent solution. Continue heating and stirring until the viscosity of the solution gradually increases to about 120 cP. After stopping heating, immediately pour the solution onto a clean glass plate that has been prepared in advance. Use a perforated mold to control the shape, area and thickness of the film. Allow the solvent to evaporate completely under natural conditions. After it dries and forms a film, remove it and dry it in a vacuum oven at -60 kPa and 60 °C for 2 hours to remove residual solvent, and obtain a 0.05% mass concentration PLA-doped film of formula (I), which is the biodegradable agricultural light-converting film.

[0079] Comparative Example 1

[0080] Undoped PLA film.

[0081] The undoped PLA film has a very weak ability to absorb ultraviolet light, and it is not capable of converting ultraviolet and blue-green light, which are detrimental to plant growth, into red light that can be absorbed and utilized.

[0082] Experimental Example 1

[0083] This test example examined the structure and spectral properties of the thin film doped material with light-conversion function shown in formula (I) obtained in this invention.

[0084] The NMR and mass spectrometry results of the optically convertible thin film doped material with optical conversion function shown in Formula (I) obtained in Example 1 are as follows:

[0085] 1 H NMR (400MHz, Chloroform-d) δ8.72 (s, 1H), 8.43 (s, 1H), 7.58 (d, J=9.2Hz, 2H), 7.19–7.14 (m, 6H), 7.14 (d, J=2.5Hz, 2H), 7.13–7.10 (m, 3H), 7.10–7.02 (m, 6H).

[0086] 13C NMR (101MHz, Chloroform-d) δ153.96, 146.05, 143.35, 143.32, 143.22, 142.36, 139.79, 133.49, 132.23, 131.69, 1 31.39, 131.35, 131.32, 128.26, 128.00, 127.91, 127.74, 127.71, 126.98, 126.80, 126.76, 125.72, 117.63, 114.53.

[0087] HRMS(ESI): m / z: Calcd.for C 64 H 42 N4S: 899.3208[M+H]+; Found: 899.3175.

[0088] The structures of the thin film doped materials with light-converting function shown in formula (I) obtained in other embodiments of the present invention were also detected by nuclear magnetic resonance and mass spectrometry, and the results were basically consistent with those of Example 1.

[0089] The fluorescence spectrum of the 1% mass concentration polylactic acid film doped with formula (I) obtained in Example 1 was detected, and the results are as follows: Figure 1 As shown.

[0090] from Figure 1 It can be seen that the emission range of the 1% PLA doped film is between 510 and 750 nm, with the maximum emission peak at 610 nm, which is consistent with the absorption wavelength range of plants.

[0091] The UV-Vis absorption and fluorescence spectra of the 0.1% mass concentration polylactic acid (I) doped film obtained in Example 2 were analyzed, and the results are as follows: Figure 2 and Figure 3 As shown.

[0092] from Figure 2 It can be seen that the absorption spectrum of the doped film is in the blue-violet light range, which is consistent with the description of this invention, and can meet the requirement of absorbing light waves that plants require less of in natural light.

[0093] from Figure 3 It can be seen that the emission peak of PLA film with a lower doping ratio is the same as that of PLA film with a higher doping ratio, indicating that the control of the film doping ratio does not affect the luminescence performance of the material.

[0094] The UV-Vis absorption and fluorescence spectra of polylactic acid films with other doping amounts obtained in other embodiments were also detected, and the results were basically consistent with those of Example 2.

Claims

1. A thin film doped material having a light conversion function, characterized in that, The material has a structure as shown in formula (I):

2. A method for preparing a thin-film doped material with light-conversion function as described in claim 1, characterized in that, The synthetic route of this preparation method is as follows: The preparation method includes the following steps: Step 1: Weigh 1-(4-cyanomethylphenyl)-1,2,2-tristyrene and Lewis base into a two-necked flask. Replace the air in the flask with nitrogen, add an alcohol solvent, and heat to react. Add benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde under a nitrogen atmosphere to continue the reaction. Step 2: After the reaction is completed, the reaction solution is cooled and poured into a large amount of water. Dichloromethane is used for extraction, the organic phases are combined, anhydrous magnesium sulfate is added for drying, and the residue obtained by filtration and vacuum concentration is separated by silica gel column chromatography. After solvent is evaporated under vacuum, a red powder is obtained, which is the thin film doped material with light conversion function shown in formula (I).

3. The preparation method according to claim 2, characterized in that, In step 1, the ratio of 1-(4-cyanomethylphenyl)-1,2,2-triphenylene: Lewis base: alcohol solvent: benzo[C][1,2,5]thiadiazole-4,7-dicarboxaldehyde is 1.0 mmol: 1.0-1.5 mmol: 20-40 mL: 0.4-0.5 mmol.

4. The preparation method according to claim 2, characterized in that, In step 1, the heating reaction is carried out at 40-60°C for 25-35 minutes, and the reaction continues for 8-16 hours.

5. The preparation method according to claim 2, characterized in that, In step 2, the eluent used for silica gel column chromatography is a mixture of chloroform and petroleum ether in a volume ratio of 1:

1.

6. A biodegradable agricultural light-converting film, wherein the biodegradable agricultural light-converting film is prepared by mixing the light-converting film doping material of claim 1 with polylactic acid.

7. A method for preparing the biodegradable agricultural light-converting film according to claim 6, characterized in that, The preparation method is as follows: The light-converting film doped material and polylactic acid particles shown in formula (I) of claim 1 are placed in a clean small beaker, an organic solvent is added, and the mixture is heated and stirred until completely dissolved to form a uniform and transparent solution. The solution viscosity is gradually increased by continuing to heat and stir. After heating is stopped, the solution is immediately poured onto a clean glass plate that has been prepared in advance. The shape, area and thickness of the film are controlled by a perforated mold. The solvent is allowed to evaporate completely under natural conditions. After the film dries and forms a film, it is removed and the residual solvent is removed using a vacuum oven to obtain the biodegradable agricultural light-converting film.

8. The preparation method according to claim 7, characterized in that, The mass ratio of the thin film doped material to the polylactic acid particles is 1g:100-10000g, and the mass-volume ratio of the polylactic acid particles to the organic solvent is 1g:10-50mL.

9. The preparation method according to claim 7, characterized in that, The viscosity of the solution after continuous heating and stirring is 50–150 cP.

10. The preparation method according to claim 7, characterized in that, The heating temperature is 40~90℃; the pressure of the vacuum oven is -40~-80kPa, and the temperature is 40~80℃.

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