Polypyrone, preparation method and application

Abstract

The invention provides a preparation method and application of polypyrone, and belongs to the technical field of fluorescent materials and preparation.The preparation method of the polypyrone comprises the steps that malonic acid, acetic anhydride and dimethylaminopyridine with the molar ratio being 1: (2-10): (0.001-0.1) are mixed and then continuously stirred for 5-10 h at the temperature of 110-170 DEG C, and a crude product is obtained through a reaction; mixing the crude product with a precipitation reagent, stirring for 5-60 minutes, then carrying out vacuum suction filtration on the mixed slurry, and washing and drying the separated solid powder to obtain the polypyrone. Compared with a catalyst-free aromatic condensation method, the preparation method provided by the invention has the advantages that the polymerization degree of the polypyrone is improved by 10-200 times, the obtained polypyrone is non-toxic, visible light-near infrared light emission can be realized, and the application range and the application field are greatly expanded.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent materials and preparation thereof, and in particular to a polypyrone, a preparation method and application thereof. Background Art

[0002] Organic photoluminescent materials have developed into a very important class of optical materials, and have important applications in various optical display fields. Polypyrone is a conjugated compound with adjustable molecular weight, which is non-toxic and environmentally friendly.

[0003] Pyrone (English name pyrone) is a ketone derivative of pyran, a class of six-membered oxygen-containing heterocyclic compounds with a molecular formula of C5H4O2. Like pyran, pyrone can have two isomers according to the position of the double bond and carbonyl group in the ring: α-pyrone and γ-pyrone. Among them, α-pyrone, also known as coumalin, can be regarded as the lactone of 5-hydroxy-2,4-pentadienoic acid. It is a colorless liquid with a hay smell, miscible with water and soluble in ethanol; γ-pyrone is a colorless hygroscopic crystal, easily soluble in water, ether, chloroform and acetic acid. These two pyran nuclei have not been found in nature, and those that exist naturally are their derivatives. The structure of pyrone is widely present in natural products.

[0004] The existing synthesis methods of polypyrone can be roughly divided into three categories: the first category is a preparation method without using solvents and catalysts, and its yield is extremely low; the second category is a preparation method using solvents and catalysts, and the yield can reach 80%, but due to the use of solvents and catalysts, the preparation process has toxic or radioactive environmental pollution, and it is not suitable for use near people or their environment; the third category is a preparation method using solvents but no catalysts, such as aromatization condensation, but its yield is only about 15%, and the number of pyrone polymerization units in the resulting polymer is 8-17, the degree of polymerization is low and there are more impurities.

[0005] In view of the fact that all current synthesis methods have a degree of polymerization of no more than 40 polymer units, and that existing studies have only shown that the maximum fluorescence emission of polypyrone synthesized by the condensation-aromatization method in solution is concentrated in the blue light band and does not have adjustable performance over a larger wavelength range, research in the optical field is almost blank, and both the synthesis method and the scope of application need to be developed. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention provides a polypyrone, a preparation method and an application thereof. The preparation method has the advantages of high yield of the target product, and the obtained polypyrone is non-toxic, has a high degree of polymerization, and has visible light-near infrared light luminescence performance.

[0007] The specific content of the invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing polypyrone, the preparation method comprising the following steps:

[0009] S1. Mix malonic acid, acetic anhydride and dimethylaminopyridine in a molar ratio of 1:2-10:0.001-0.1, and stir continuously for 5-10 hours at 110-170°C to obtain a crude product;

[0010] S2. After mixing the crude product with a precipitating agent, stirring for 5-60 minutes, and then vacuum filtering the mixed slurry, washing and drying the separated solid powder to obtain the polypyrone.

[0011] Optionally, in step S1, the reaction to obtain a crude product is carried out in a heating reflux device, and the method comprises: adding the malonic acid, acetic anhydride and dimethylaminopyridine into a three-necked flask, using the three-necked flask to build a heating reflux device, and exhausting residual air in the device.

[0012] Optionally, the exhausting the residual air in the device comprises: introducing a purge gas into the three-necked flask for 10-60 minutes to exhaust the residual air in the device;

[0013] The purge gas is He, Ar or N2.

[0014] Optionally, in step S1, before carrying out the operation of continuously stirring at 110-170° C. for 5-10 hours, the method further comprises: preheating the mixture of malonic acid, acetic anhydride and dimethylaminopyridine to fully dissolve the reaction raw materials.

[0015] Optionally, the preheating temperature is 70-110° C. and the preheating time is 5-60 min.

[0016] Optionally, in step S2, the washing comprises: using a precipitation reagent as a washing agent, and washing thoroughly for 3-5 times;

[0017] The drying temperature is 80-120°C.

[0018] Optionally, the precipitation reagent is at least one of ethanol, tert-butanol, ethyl acetate, water and diethyl ether.

[0019] In a second aspect, the present invention provides a polypyrone obtained by the preparation method described in the first aspect, wherein the polypyrone is a continuous structure having 20 to 5000 pyrone polymerization units represented by formula I:

[0020]

[0021] In the continuous structure, the ratio of α-pyrone units to γ-pyrone units is 1 to 4:1.

[0022] Optionally, the fluorescence emission range of the polypyrone is visible light to near-infrared light.

[0023] In a third aspect, the present invention provides an application of polypyrone obtained by the preparation method described in the first aspect. The polypyrone is used as an organic photoluminescent material in the preparation of organic electroluminescent related devices.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention provides a method for preparing polypyrone, comprising mixing malonic acid, acetic anhydride and dimethylaminopyridine in a molar ratio of 1:2-10:0.001-0.1, stirring continuously for 5-10 hours at 110-170°C, and reacting to obtain a crude product; mixing the crude product with a precipitation reagent, stirring for 5-60 minutes, and then vacuum filtering the mixed slurry, washing and drying the separated solid powder to obtain the polypyrone. Compared with the aromatic condensation method without a catalyst, the preparation method provided by the present invention increases the polymerization degree of polypyrone by 10-200 times, and the obtained polypyrone is non-toxic and can realize visible light-near infrared luminescence, which greatly expands the scope and application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The flowchart of the preparation method of polypyrone provided by the embodiment of the present invention is shown;

[0028] Figure 2 The excitation and emission spectra of the polypyrone in a thin film state provided by an embodiment of the present invention are shown;

[0029] Figure 3 The fluorescence spectra of 4-valerolactone solutions of polypyrone containing different ions provided in the embodiments of the present invention are shown. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work belong to the scope of protection of the present invention.

[0031] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0032] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0033] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] The present invention is based on solving the problems of environmental pollution in the existing preparation process of polypyrone, low yield of target product, low degree of polymerization of the obtained polypyrone, and small fluorescence wavelength range of polypyrone, and provides a polypyrone, a preparation method and application. The specific implementation contents are as follows:

[0036] In a first aspect, the present invention provides a method for preparing polypyrone. Figure 1 The flow chart of the preparation method of polypyrone provided in the embodiment of the present invention is shown, Figure 1 As shown, the preparation method comprises the following steps:

[0037] S1. Mix malonic acid, acetic anhydride and dimethylaminopyridine in a molar ratio of 1:2-10:0.001-0.1, and stir continuously for 5-10 hours at 110-170°C to obtain a crude product;

[0038] When the operation process of step S1 is specifically implemented, the reaction is specifically carried out in a heating reflux device, and the operation process includes: adding malonic acid, acetic anhydride and dimethylaminopyridine into a three-necked flask, and then using the three-necked flask to build a heating reflux device, and then passing a purge gas into the three-necked flask for 10-60 minutes to exhaust the residual air in the device. Among them, the purge gas can be selected from He, Ar or N2.

[0039] Furthermore, after exhausting the residual air in the device, the three-necked flask containing malonic acid, acetic anhydride and dimethylaminopyridine is preheated at a temperature of 70-110°C for 5-60 minutes to fully dissolve the reaction raw materials; after the reaction raw materials are fully dissolved, the heating temperature is increased to 110-170°C to allow the polymerization reaction to proceed fully. This reaction process can be considered to be completed in three steps:

[0040] In the first step, malonic acid and acetic anhydride react to form a long-chain intermediate under the action of dimethylaminopyridine. The reaction formula is as follows:

[0041]

[0042] In the second step, the long-chain intermediate further removes the carboxyl group to form tricarbon dioxide (C3O2). The reaction formula is as follows:

[0043]

[0044] In the third step, since acetic anhydride is excessive in the reaction raw materials, the carbon dioxide generated in the system further polymerizes with the remaining unreacted acetic anhydride and dimethylaminopyridine to finally generate polypyrone. The reaction formula is as follows:

[0045]

[0046] From the above reaction process, it can be seen that dimethylaminopyridine, as a catalyst in the first step reaction, promotes the reaction between malonic acid and acetic anhydride to form an intermediate, and then one molecular weight of the intermediate removes two molecular weights of acetic acid to obtain a large amount of tricarbon dioxide (C3O2); at the same time, dimethylaminopyridine reacts with the remaining unreacted acetic anhydride to form acetate ions, which initiate the polymerization reaction of C3O2, thereby generating polypyrone.

[0047] S2. After mixing the crude product with a precipitating agent, stirring for 5-60 minutes, and then vacuum filtering the mixed slurry, washing and drying the separated solid powder to obtain the polypyrone.

[0048] When the operation process of step S2 is specifically implemented, in order to extract high-purity polypyrone from the reaction system, the present invention uses at least one of ethanol, tert-butanol, ethyl acetate, water and ether as a precipitating agent, which is mixed with the crude product. Due to the difference in solubility of polypyrone in the precipitating agent and acetic anhydride, the polypyrone in the mixed slurry is precipitated under stirring conditions, and vacuum filtration is performed to separate the solid powder of polypyrone. The solid powder is washed 3-5 times with the precipitating agent and then dried (at a temperature of 80-120° C.) to finally obtain polypyrone with a purity of more than 95%.

[0049] In the preparation method provided by the present invention, dimethylaminopyridine is used as a catalyst for the first step reaction, which promotes the reaction between malonic acid and acetic anhydride to form an intermediate, and then promotes the formation of a large amount of monomer C3O2 of polypyrone through a deacetic acid reaction; the polymerization degree of polypyrone is increased by 10-200 times, and the obtained polypyrone is non-toxic and can realize visible light-near infrared luminescence, thereby greatly expanding the scope and application field.

[0050] In a second aspect, the present invention provides a polypyrone obtained by the preparation method described in the first aspect, wherein the polypyrone is a continuous structure having 20 to 5000 pyrone polymerization units represented by formula I:

[0051]

[0052] In the continuous structure, the ratio of α-pyrone units to γ-pyrone units is 1 to 4:1.

[0053] Since the polypyrone provided in this embodiment has a continuous structure of 20-5000 pyrone polymerization units shown in Formula I, the number of continuous structural units, that is, the length of the conjugated path is adjustable, which determines the fluorescence with a larger wavelength range that can be achieved.

[0054] In a third aspect, the present invention provides an application of polypyrone obtained by the preparation method described in the first aspect, wherein the polypyrone is used as an organic photoluminescent material in the preparation of organic photoluminescent related devices, and can be used as a light-excited anti-counterfeiting display material with good light stability.

[0055] In order to enable those skilled in the art to more clearly understand the present invention, the polypyrone, preparation method and application of the present invention are now described in detail through the following examples.

[0056] Example 1

[0057] Weigh acetic anhydride, malonic acid and dimethylaminopyridine in a three-necked flask. The molar ratio of malonic acid to acetic anhydride can be controlled to be 1:3; the molar ratio of malonic acid to dimethylaminopyridine is 1:0.01. Build a reflux experimental device, and then pass purge gas (Ar) into the three-necked flask for 25 minutes to fully exhaust the residual air in the device.

[0058] Preheat the three-necked flask to 110°C and keep it for 30 minutes to fully dissolve the reaction raw materials. The stirring speed is 150r / min. Raise the temperature to 130°C and keep it for 5 hours to obtain the reaction product. The stirring speed is 300r / min. Stop the reaction and let the reaction product cool naturally to room temperature. At the same time, pass the purge gas (Ar) into the three-necked flask for 50 minutes to fully discharge the residual product gas in the reaction device.

[0059] The reaction product was transferred to a beaker, and 250 ml of precipitation reagent (ethanol) was added, and magnetic stirring was performed for 25 minutes. The slurry was vacuum filtered to obtain a solid powder, and the solid powder was fully washed with the precipitation reagent for 5 times. The washed solid powder was placed in an oven and fully dried at 105°C to obtain a product powder with a purity greater than 95%.

[0060] The prepared polypyrone was dissolved in DMF solvent, and the continuous structure of polypyrone with an average of 40 polymerization units and a maximum of 400 polymerization units was measured by gel permeation chromatography (GPC). The polypyrone powder was heated to 1000°C (Ar) using a thermogravimetric-mass spectrometry-infrared device, and the ratio of CO2 and CO generated during the pyrolysis of the sample was tested, and the ratio of α-pyrone units to γ-pyrone units in the polypyrone structure was measured to be 2:1.

[0061] The obtained polypyrone is dissolved in 4-valerolactone solvent to form a solution, and then the above solution is dropped onto a silicon wafer or a quartz wafer substrate, and dried at 60° C. to obtain a film.

[0062] Figure 2 The excitation and emission spectra of the polypyrone provided by the embodiment of the present invention in the thin film state are shown, such as Figure 2 As shown, the prepared film can achieve fluorescence emission in the visible-near-infrared range.

[0063] Further, polypyrone was dissolved in 4-valerolactone, and then the above solution was added dropwise to the Li + ,Na + ,K + Mg 2+ ,Ca 2+ ,Cu 2+ ,Al 3+ ,Ni 2+ or Fe 3+In the aqueous solution of ions, the fluorescence intensity and emission wavelength of the mixed solution are characterized by steady-state fluorescence spectroscopy.

[0064] Figure 3 FIG. 4 shows the fluorescence spectra of 4-valerolactone solutions of polypyrone containing different ions provided in the embodiments of the present invention, such as Figure 3 As shown, the results show that compared with the blank polypyrone 4-valerolactone solution, Li + ,Na + ,K + ions increase the fluorescence intensity, and the maximum emission wavelength does not change much; Mg 2+ ,Ca 2+ and Al 3+ ions increase the fluorescence intensity and blue-shift the maximum emission wavelength. 2+ and Ni 2+ ions reduce the fluorescence intensity and blue-shift the maximum emission wavelength; Fe 3+ Ions significantly reduce the fluorescence intensity. This shows that the polypyrone prepared in this example has great application potential in the field of fluorescent metal ion probes.

[0065] Example 2

[0066] Weigh acetic anhydride, malonic acid and dimethylaminopyridine in a three-necked flask. The molar ratio of malonic acid to acetic anhydride can be controlled to be 1:4; the molar ratio of malonic acid to dimethylaminopyridine is 1:0.01. Build a reflux experimental device, and then pass a purge gas (He) into the three-necked flask for 40 minutes to fully exhaust the residual air in the device.

[0067] Preheat the three-necked flask to 100°C and keep it for 20 minutes to fully dissolve the reaction raw materials. The stirring speed is 400r / min. Raise the temperature to 120°C and keep it for 6 hours to obtain the reaction product. The stirring speed is 400r / min. Stop the reaction and let the reaction product cool naturally to room temperature. At the same time, pass the purge gas (He) into the three-necked flask for 30 minutes to fully discharge the residual product gas in the reaction device.

[0068] The reaction product was transferred to a beaker, and 250 ml of a precipitating agent (tert-butyl alcohol) was added, and magnetic stirring was performed for 35 min. The above slurry was vacuum filtered to obtain a solid powder, and the solid powder was fully washed three times with a precipitating agent. The washed solid powder was placed in an oven and fully dried at 120°C to obtain a product powder with a purity greater than 95%. The prepared polypyrone was dissolved in NMP solvent, and the continuous structure of the polypyrone with an average of 90 polymerization units and a maximum of 600 polymerization units was measured by gel permeation chromatography (GPC). The polypyrone powder was heated to 1000°C (He) using a thermogravimetric-mass spectrometry-infrared coupling device, and the ratio of CO2 and CO generated during the pyrolysis of the sample was tested. The ratio of α-pyrone units to γ-pyrone units in the structure was 3:1.

[0069] The obtained polypyrone was dissolved in a DMSO solvent to form a solution, and then the above solution was added dropwise to a silicon wafer or a quartz wafer substrate, and dried at 80° C. to obtain a film. In this example, the fluorescence emission of the obtained film in the visible light-near infrared range was tested, and the test results were highly similar to those in Example 1, and the figures used to characterize the results are not repeated.

[0070] Further, polypyrone was dissolved in 4-valerolactone, and then the above solution was added dropwise to the Li + ,Na + ,K + Mg 2+ ,Ca 2+ ,Cu 2+ ,Al 3+ ,Ni 2+ or Fe 3+ In the aqueous solution of ions, the fluorescence intensity and emission wavelength of the mixed solution are characterized by steady-state fluorescence spectroscopy. The results of the figures used for characterization are highly similar to those of Example 1 and are not repeated here.

[0071] Example 3

[0072] Weigh acetic anhydride, malonic acid and dimethylaminopyridine in a three-necked flask. The molar ratio of malonic acid to acetic anhydride can be controlled to be 1:5; the molar ratio of malonic acid to dimethylaminopyridine is 1:0.003. Build a reflux experimental device, and then pass purge gas (He) into the three-necked flask for 50 minutes to fully exhaust the residual air in the device.

[0073] Preheat the three-necked flask to 100°C and keep it for 15 minutes to fully dissolve the reaction raw materials. The stirring speed is 300r / min. Raise the temperature to 130°C and keep it for 10 hours to obtain the reaction product. The stirring speed is 500r / min. Stop the reaction and let the reaction product cool naturally to room temperature. At the same time, pass the purge gas (He) into the three-necked flask for 30 minutes to fully discharge the residual product gas in the reaction device.

[0074] The reaction product was transferred to a beaker, and 400 ml of a precipitating agent (50% water, 50% ethanol) was added, and magnetic stirring was performed for 20 minutes. The above slurry was vacuum filtered to obtain a solid powder, and the solid powder was fully washed 4 times with a precipitating agent. The washed solid powder was placed in an oven and fully dried at 90°C to obtain a product powder with a purity greater than 95%. The prepared polypyrone was dissolved in NMP solvent, and the continuous structure of the polypyrone with an average of 35 polymerization units and a maximum of 150 polymerization units was measured by gel permeation chromatography (GPC). The polypyrone powder was heated to 1000°C (He) using a thermogravimetric-mass spectrometry-infrared coupling device, and the ratio of CO2 and CO generated during the pyrolysis of the sample was tested. The ratio of α-pyrone units to γ-pyrone units in the structure was 3.5:1.

[0075] The obtained polypyrone was dissolved in NMP solvent to form a solution, and then the above solution was added dropwise to a silicon wafer or a quartz wafer substrate, and dried at 100° C. to obtain a film. In this example, the fluorescence emission of the obtained film in the visible light-near infrared range was tested, and the test results were highly similar to those in Example 1, and the figures used to characterize the results are not repeated.

[0076] Further, polypyrone was dissolved in 4-valerolactone, and then the above solution was added dropwise to the Li + ,Na + ,K + Mg 2+ ,Ca 2+ ,Cu 2+ ,Al 3+ ,Ni 2+ or Fe 3+ In the aqueous solution of ions, the fluorescence intensity and emission wavelength of the mixed solution are characterized by steady-state fluorescence spectroscopy. The results of the figures used for characterization are highly similar to those of Example 1 and are not repeated here.

[0077] Example 4

[0078] Weigh acetic anhydride, malonic acid and dimethylaminopyridine in a three-necked flask. The molar ratio of malonic acid to acetic anhydride can be controlled to be 1:10; the molar ratio of malonic acid to dimethylaminopyridine is 1:0.006. Build a reflux experimental device, and then pass purge gas (Ar) into the three-necked flask for 60 minutes to fully exhaust the residual air in the device.

[0079] Preheat the three-necked flask to 110°C and keep it for 45 minutes to fully dissolve the reaction raw materials. The stirring speed is 500r / min. Raise the temperature to 150°C and keep it for 8 hours to obtain the reaction product. The stirring speed is 800r / min. Stop the reaction and cool the reaction product naturally to room temperature. At the same time, pass the purge gas (Ar) into the three-necked flask for 30 minutes to fully discharge the residual product gas in the reaction device.

[0080] The reaction product was transferred to a beaker, and 400 ml of a precipitating agent (ethyl acetate) was added, and magnetic stirring was performed for 40 minutes. The above slurry was vacuum filtered to obtain a solid powder, and the solid powder was fully washed with a precipitating agent (ethyl acetate) for 5 times. The washed solid powder was placed in an oven and fully dried at 110°C to obtain a product powder with a purity greater than 95%. The prepared polypyrone was dissolved in NMP solvent, and the continuous structure of the polypyrone with an average of 110 polymerization units and a maximum of 720 polymerization units was measured by gel permeation chromatography (GPC). The polypyrone powder was heated to 1000°C (He) using a thermogravimetric-mass spectrometry-infrared coupling device, and the ratio of CO2 and CO generated during the pyrolysis of the sample was tested. The ratio of α-pyrone units to γ-pyrone units in the structure was 4:1.

[0081] The obtained polypyrone was dissolved in a DMF solvent to form a solution, and then the above solution was added dropwise to a silicon wafer or a quartz wafer substrate, and dried at 80° C. to obtain a film. In this example, the fluorescence emission of the obtained film in the visible light-near infrared range was tested, and the test results were highly similar to those in Example 1, and the figures used to characterize the results are not repeated.

[0082] Further, polypyrone was dissolved in 4-valerolactone, and then the above solution was added dropwise to the Li + ,Na + ,K + Mg 2+ ,Ca 2+ ,Cu 2+ ,Al 3+ ,Ni 2+ or Fe 3+ In the aqueous solution of ions, the fluorescence intensity and emission wavelength of the mixed solution are characterized by steady-state fluorescence spectroscopy. The results of the figures used for characterization are highly similar to those of Example 1 and are not repeated here.

[0083] Example 5

[0084] Weigh acetic anhydride, malonic acid and dimethylaminopyridine in a three-necked flask. The molar ratio of malonic acid to acetic anhydride can be controlled to be 1:5; the molar ratio of malonic acid to dimethylaminopyridine is 1:0.05. Build a reflux experimental device, and then pass purge gas (N2) into the three-necked flask for 60 minutes to fully exhaust the residual air in the device.

[0085] Preheat the three-necked flask to 100°C and keep it for 15 minutes to fully dissolve the reaction raw materials. The stirring speed is 400r / min. Raise the temperature to 150°C and keep it for 5 hours to obtain the reaction product. The stirring speed is 1500r / min. Stop the reaction and cool the reaction product naturally to room temperature. At the same time, pass the purge gas (N2) into the three-necked flask for 10 minutes to fully discharge the residual product gas in the reaction device.

[0086] The reaction product was transferred to a beaker, and 300 ml of a precipitation agent (ether) was added, and magnetic stirring was performed for 15 minutes. The above slurry was vacuum filtered to obtain a solid powder, and the solid powder was fully washed with a precipitation agent for 3-5 times. The washed solid powder was placed in an oven and fully dried at 80°C to obtain a product powder with a purity greater than 95%. The prepared polypyrone was dissolved in NMP solvent, and the continuous structure of the polypyrone with an average of 150 polymerization units and a maximum of 2000 polymerization units was measured by gel permeation chromatography (GPC). The polypyrone powder was heated to 1000°C (He) using a thermogravimetric-mass spectrometry-infrared device, and the ratio of CO2 and CO generated during the pyrolysis of the sample was tested. The ratio of α-pyrone units to γ-pyrone units in the structure was 3:1.

[0087] The obtained polypyrone is dissolved in a 4-valerolactone solvent to form a solution, and then the above solution is added dropwise to a silicon wafer or a quartz wafer substrate, and dried at 80° C. to obtain a film. In this example, the fluorescence emission of the obtained film in the visible light-near infrared range is tested, and the test results are highly similar to those in Example 1, and the figures used to characterize the results are not repeated.

[0088] Further, polypyrone was dissolved in 4-valerolactone, and then the above solution was added dropwise to the Li + ,Na + ,K + Mg 2+ ,Ca 2+ ,Cu 2+ ,Al 3+ ,Ni 2+ or Fe 3+In the aqueous solution of ions, the fluorescence intensity and emission wavelength of the mixed solution are characterized by steady-state fluorescence spectroscopy. The results of the figures used for characterization are highly similar to those of Example 1 and are not repeated here.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0090] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0091] The above is a detailed introduction to a polypyrone, a preparation method and an application provided by the present invention. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing polypyrone, characterized in that: The preparation method comprises the following steps: S1. Mix malonic acid, acetic anhydride and dimethylaminopyridine in a molar ratio of 1:2-10:0.001-0.1, and stir continuously for 5-10 hours at 110-170°C to obtain a crude product; S2. After mixing the crude product with a precipitating agent, stirring for 5-60 minutes, and then vacuum filtering the mixed slurry, washing and drying the separated solid powder to obtain the polypyrone.

2. The method for preparing polypyrone according to claim 1, characterized in that: In step S1, the reaction to obtain a crude product is carried out in a heating reflux device, and the method comprises: adding the malonic acid, acetic anhydride and dimethylaminopyridine into a three-necked flask, using the three-necked flask to build a heating reflux device, and exhausting the residual air in the device.

3. The method for preparing polypyrone according to claim 2, characterized in that: Expelling the residual air in the device comprises: passing a purge gas into the three-necked flask for 10-60 minutes to exhaust the residual air in the device; The purge gas is He, Ar or N2.

4. The method for preparing polypyrone according to claim 1, characterized in that: In step S1, before carrying out the operation of continuously stirring at 110-170° C. for 5-10 hours, the method further comprises: preheating the mixture of malonic acid, acetic anhydride and dimethylaminopyridine to fully dissolve the reaction raw materials.

5. The method for preparing polypyrone according to claim 4, characterized in that: The preheating temperature is 70-110° C. and the preheating time is 5-60 min.

6. The method for preparing polypyrone according to claim 1, characterized in that: In step S2, the washing comprises: using a precipitation reagent as a washing agent, washing thoroughly 3-5 times; The drying temperature is 80-120°C.

7. The method for preparing polypyrone according to claim 1 or 6, characterized in that: The precipitation reagent is at least one of ethanol, tert-butanol, ethyl acetate, water and ether.

8. A polypyrone obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The polypyrone is a continuous structure having 20 to 5000 pyrone polymerization units shown in formula I: In the continuous structure, the ratio of α-pyrone units to γ-pyrone units is 1 to 4:

1.

9. The use according to claim 8, characterized in that: The fluorescence emission range of the polypyrone is visible light to near-infrared light.

10. An application of polypyrone obtained by the preparation method according to any one of claims 1 to 6, characterized in that: The polypyrone is used as an organic photoluminescent material and is applied in the preparation of organic photoluminescent related devices.

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