CN117126131A - Efficient synthesis method of gamma-thiopyranone derivative - Google Patents

Abstract

The invention belongs to the technical field of organic light emission, and discloses a high-efficiency synthesis method of a gamma-thiopyranone derivative. The method comprises the following steps: the preparation method comprises the steps of taking a polar organic solvent as a reaction medium, and reacting a thiadiazole compound with a 4-hydroxy pyrone compound under the action of an alkaline compound to obtain the gamma-thiopyranone derivative. The structure of the gamma-thiopyranone derivative is shown as a formula III. The method has mild reaction conditions, does not need a transition metal catalyst, has low energy consumption, is favorable for environmental protection and is favorable for industrialized mass production; the method has high chemical selectivity, high product yield, wide range of reaction substrates and strong functional group compatibility. The fluorescent organic compound prepared from the gamma-thiopyranone derivative has the characteristics of wide absorption range, large Stokes shift, longer emission wavelength and the like as a fluorescent probe.

Description

An efficient synthesis method of γ-thiopyrone derivatives

Technical field

The invention belongs to the field of organic light-emitting technology, and specifically relates to an efficient synthesis method of γ-thiopyrone derivatives.

Background technique

Derivatives with γ-pyrone or γ-thiopyrone as the core skeleton are widely used in the field of fluorescent probes, such as protein detection (Design and Synthesis of Intramolecular Charge Transfer-BasedFluorescent Reagents for the Highly-Sensitive Detection ofProteins.J.Am.Chem.Soc.2005,127,17799-17802), amino acid detection (A red-emittingfluorescent probe with large Stokes shift for real-time tracking of cysteineover glutathione and homocysteine in living cells.Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.2019,214,469–475), thiol detection (Photophysical Properties and Ultrafast Excited-State Dynamics of a New Two-Photon Absorbing Thiopyranyl Probe.J.Phys.Chem.C 2013,117,11941-11952), etc. Of course, such compounds also have aggregation-induced emission (AIE) effect (Aggregation-Induced Emission of4-Dicyanomethylene-2,6-distyryl-4H-pyran.J.Chin.Chem.Soc.2006,53,243-246), targeted positioning Novel mitochondria-targeted, nitrogen mustard-based DNAalkylation agents with near infrared fluorescence emission. Talanta, 2016, 161888–893), Synthesis and second-order optical nonlinearities of chiral nonracemic “Y-shaped” chromophores. Synthetic Metals, 2004, 142, 259–262) and other optical properties.

At present, the main synthesis method of γ-thiopyrone is to use propyne as the starting material, react with methyl formate under the action of n-butyllithium to form diacetylenic alcohol, and then be oxidized to diacetylenic alcohol by manganese dioxide or barium manganate. The acetylenone is then cyclized with thiourea to construct the γ-thiopyrone skeleton. The reaction strategy requires the use of harsh conditions such as strong alkali, strong oxidant, and nitrogen protection. The synthesis method is single and complex, the steps are lengthy, and the conditions are harsh, making it difficult to synthesize it extensively and in large quantities. This limits the synthesis of such compounds and their applications in biomedicine, optoelectronic materials and other fields. Therefore, exploring synthetic strategies with cheap and readily available raw materials, mild reaction conditions, high selectivity, and environmental friendliness is still a very attractive research topic.

The object of the present invention is to provide an efficient synthesis method of γ-thiopyrone derivatives to solve many defects of existing thiopyranone synthesis, and to provide a method for synthesizing γ-thiopyrone derivatives with mild reaction conditions, cheap and easily available raw materials, and high specificity. -Methods for thiopyrone and its various derivatives.

The present invention is realized through the following technical solutions:

An efficient synthesis method of γ-thiopyrone derivatives, including the following steps: using a polar organic solvent as a reaction medium, reacting thiadiazole compounds and 4-hydroxypyrone compounds under the action of a basic compound , obtain γ-thiopyrone derivatives;

The structural formula of the thiadiazole compound is formula I

R ¹ is H, COOR′, X, OR′, CF3, CN, SR′, R′ is an alkyl group (preferably C _{1 to 5} alkyl group), , naphthyl, Het means that the cyclic group can be benzene ring, thienyl, furyl, pyridyl, naphthyl; or in the structure for/>

The structural formula of the 4-hydroxypyrone compounds is formula II

R ² is aromatic ring, heterocyclic ring, alkyl group, alkenyl group or alkynyl group;

The aryl group is a phenyl group or a naphthyl group, the alkenyl group includes a styrene group, and the alkyl group is a C _1-6 alkyl group.

The alkaline compound is at least one of cesium carbonate, sodium carbonate, potassium phosphate, potassium carbonate, potassium bicarbonate, and sodium bicarbonate; preferably, it is at least one of sodium carbonate, potassium phosphate, and potassium carbonate.

The reaction temperature is 60-100°C, and the reaction time is 1-2 days.

The molar ratio of the thiadiazole compound and the 4-hydroxypyrone compound is 1:1.1 to 1:1.5.

The polar organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone, preferably N,N-dimethylpyrrolidone. More than one of methylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

The concentration of the thiadiazole compound in the polar organic solvent is 0.5-2 mol/L.

The molar ratio of the weakly basic salt to the thiadiazole compound is 1: (1.8-2.5).

After the reaction is completed, water is extracted, and the crude product is separated by column chromatography.

The structure of the γ-thiopyrone derivative is formula III:

R ¹ , R ² and Het are as defined before.

The γ-thiopyrone derivative is used to prepare fluorescent organic compounds.

The structure of the fluorescent organic compound is

R ³ is H, OR', N(R') ₂ , SR', R' is alkyl (preferably C _{1 to 4} alkyl, such as methyl, ethyl, isopropyl, butyl), Ar (aryl, preferably phenyl, thiophene, furan), OH;

The preparation method of the fluorescent organic compound includes the following steps:

React γ-thiopyranone derivatives with malononitrile to obtain thiopyran compounds containing nitrile groups; react thiopran compounds containing nitrile groups with benzaldehyde compounds to obtain fluorescent compounds;

The γ-thiopyrone derivative is as defined above, and in this case R ² is methyl.

The structure of thiopyran compounds containing nitrile groups:

The structure of the benzaldehyde compound is

R ³ is as defined previously.

In the reaction between γ-thiopyrone derivatives and malononitrile, acetic anhydride is used as the reaction medium;

In the reaction between thiopyran compounds containing nitrile groups and benzaldehyde compounds, ethanol is used as the reaction medium and piperidine is used as the catalyst.

Compared with the existing technology, the present invention has the following advantages and beneficial effects:

(1) The reaction conditions are mild, no transition metal catalyst is needed, the reaction is carried out at a lower temperature, and the low energy consumption is conducive to environmental protection and industrial-scale production.

(2) This reaction has high chemical selectivity and high product yield.

(3) This reaction has a wide substrate range and strong functional group compatibility.

(4) The fluorescent organic compound prepared from the γ-thiopyrone derivative of the present invention has the characteristics of a wide absorption range, a large Stokes shift, and a long emission wavelength as a fluorescent probe.

Description of the drawings

Figure 1 is the hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3a;

Figure 2 is the carbon spectrum (13C NMR: 101MHz, CDCl3) of compound 3a;

Figure 3 is the hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3b;

Figure 4 is the carbon spectrum (13C NMR: 101MHz, CDCl3) of compound 3b;

Figure 5 is the hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3c;

Figure 6 is the carbon spectrum (13C NMR: 101MHz, CDCl3) of compound 3c;

Figure 7 is a hydrogen spectrum (1H NMR: 500MHz, CDCl3) chart of compound 5a;

Figure 8 is the carbon spectrum (13C NMR: 126MHz, CDCl3) of compound 5a;

Figure 9 is a hydrogen spectrum (1H NMR: 500MHz, CDCl3) chart of compound 7a;

Figure 10 is the carbon spectrum (13C NMR: 126MHz, CDCl3) of compound 7a;

Figure 11 is the absorption and emission spectra of compound 7a;

Figure 12 is the absorption and emission spectra of compound 7b;

Figure 13 is an X-ray crystal structure diagram of compound 3b.

Detailed ways

In order to better understand the present invention, the present invention will be further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Synthesis of 2-benzyl-6-methyl-4H-thiopyran-4-one 3a

4-phenyl-1,2,3-thiadiazole 1a (R ¹ =H) (0.01 mol, 1.62 g) and 4-hydroxy-6-methyl-2-pyrone 2a (0.015 mol, 1.89 g) ) as the initial raw material, then add potassium phosphate (0.02mol, 4.25g), and finally add 15ml N, N-dimethylacetamide, heat and stir the reaction in an oil bath (80°C, 1 day), wait until compound 1a reacts completely. Extract and separate with water, and the crude product is separated by column chromatography (petroleum ether: ethyl acetate = 5:1 to 2:1) to obtain compound 3a. The yield of the product prepared in this example is 90%, and the selectivity is 100%.

Product 3a structural formula:

Nuclear magnetic resonance spectrum data of product 3a: ¹ H NMR (400MHz, Chloroform-d) δ7.36-7.27 (m, 3H), 7.21 (d, J = 8.0Hz, 2H), 6.78 (s, 1H), 6.71 (s ,1H),3.88(s,2H),2.31(s,3H). ¹³ C NMR(101MHz,Chloroform-d)δ182.3,154.6,151.0,136.3,128.9,128.9,128.1,128.0,127.5,42.6,22.5. HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₁₃ H ₁₂ OS+H ⁺ 217.0681; found:217.0680.

The hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3a is shown in Figure 1, and the carbon spectrum (13CNMR: 101MHz, CDCl3) is shown in Figure 2.

Example 2

Synthesis of methyl 4-(6-methyl-4-oxo-4H-thiopyran-2-yl)methyl)benzoate 3b

Methyl 4-(1,2,3-thiadiazol-4-yl)benzoate 1b (R ¹ =CO ₂ Me) (0.01 mol, 1.62 g) and 4-hydroxy-6-methyl-2-pyra Pyrone 2a (0.015mol, 1.89g) was used as the initial raw material, then potassium phosphate (0.02mol, 4.25g) was added, and finally 15ml N,N-dimethylformamide was added, and the reaction was heated and stirred in an oil bath (80°C , 1 day) until the reaction of compound 1b is complete. Extract and separate with water, and the crude product is separated by column chromatography (petroleum ether: ethyl acetate = 5:1 to 2:1) to obtain compound 3b. The yield of the product prepared in this example was 77%, and the selectivity was 100%.

Product 3b structural formula

Product 3b nuclear magnetic resonance spectrum data: ¹ H NMR (400MHz, Chloroform-d) δ8.00 (d, J = 8.0Hz, 2H), 7.30 (d, J = 8.0Hz, 2H), 6.78 (s, 1H), 6.72(s,1H),3.93(s,2H),3.90(s,3H),2.32(s,3H). ¹³ C NMR(101MHz,Chloroform-d)δ182.0,166.5,153.3,150.8,141.4,130.1, 129.4,128.9,128.4,128.2,52.1,42.4,22.5.HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₁₅ H ₁₄ O ₃ S+H ⁺ 275.0736; found: 275.0733.

The hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3b is shown in Figure 3, and the carbon spectrum (13CNMR: 101MHz, CDCl3) is shown in Figure 4.

Example 3

Synthesis of 2-benzyl-6-styryl-4H-thiopyran-4-one 3c

4-phenyl-1,2,3-thiadiazole 1a (R ¹ =H) (0.01 mol, 1.62 g) and 4-hydroxy-6-styryl-2H-pyran-2-one 2b (0.015 mol, 3.21g) as the initial raw material, then add potassium phosphate (0.02mol, 4.25g), and finally add 15ml N,N-dimethylformamide, heat and stir the reaction in an oil bath (80°C, 1 day), Wait until the reaction of compound 1a is complete. Extract and separate with water, and the crude product is separated by column chromatography (petroleum ether: ethyl acetate = 5:1 to 2:1) to obtain compound 3c. The yield of the product prepared in this example is 40%, and the selectivity is 100%.

Product 3c structural formula:

Nuclear magnetic resonance spectrum data of product 3c: ¹ H NMR (400MHz, Chloroform-d) δ7.48 (d, J = 4.0Hz, 2H), 7.41-7.33 (m, 5H), 7.31 (d, J = 8.0Hz, 1H ),7.27(d,J＝8.0Hz,2H),7.13(d,J＝16.0Hz,1H),6.91(d,J＝16.0Hz,1H),6.87(s,1H),6.81(s,1H ),3.95(s,2H). ¹³ C NMR(101MHz,Chloroform-d)δ182.6,153.5,149.5,136.2,135.1,135.0,129.5,129.0,129.0,128.9,128.5,127.6,127.4,127.3,125.1 ,43.0 .HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₂₀ H ₁₆ OS+H ⁺ 305.0995; found:305.0992.

The hydrogen spectrum (1H NMR: 400MHz, CDCl3) of compound 3c is shown in Figure 5, and the carbon spectrum (13CNMR: 101MHz, CDCl3) is shown in Figure 6.

Example 4

Synthesis of 2-(4-methoxybenzyl)-6-methylthiopyran-4-one 3d

In Example 1, 4-phenyl-1,2,3-thiadiazole 1a is replaced with 4-(4-methoxyphenyl)-1,2,3-thiadiazole 1c, and the rest is the same as in Example 1 In the same manner, product 3d was obtained with a yield of 82%.

Product 3d nuclear magnetic resonance spectrum data: ¹ H NMR (400MHz, CDCl ₃ ) δ7.12 (d, J = 10.0Hz, 2H), 6.84 (d, J = 10.0Hz, 2H), 6.75 (s, 1H), 6.69 (s,1H),3.82(s,2H),3.77(s,3H),2.30(s,3H). ¹³ CNMR(101MHz,CDCl ₃ )δ182.3,158.9,155.2,150.9,130.0,128.2,128.0,127.7 ,114.2,55.2,41.8,22.5.HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₁₄ H ₁₄ O ₂ S+H ⁺ 247.0787; found:247.0786.

Example 5

Synthesis of 2-methyl-6-(4-methylthio)benzyl-4H-thiopyran-4-one 3e

In Example 1, 4-phenyl-1,2,3-thiadiazole 1a is replaced with 4-(4-methylthio)phenyl-1,2,3-thiadiazole 1d, and the rest is the same as in Example 1 In the same manner, product 3e was obtained with a yield of 77%.

Product 3e nuclear magnetic resonance spectrum data: ¹ H NMR (500MHz, CDCl ₃ ) δ7.21 (d, J = 5.0 Hz, 2H), 7.13 (d, J = 10.0 Hz, 2H), 6.77 (s, 1H), 6.72 (s,1H),3.84(s,2H),2.46(s,3H),2.32(s,3H). ¹³ CNMR(126MHz,CDCl ₃ )δ182.3,154.6,151.0,137.9,132.9,129.4,128.1,128.0 ,126.9,42.1,22.6,15.7.HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₁₄ H ₁₄ OS ₂ +H ⁺ 263.0559; found:263.0558.

Example 6

Synthesis of 2-(benzo[d][1,3]dioxol-5-ylmethyl)-6-methyl-4H-thiopyran-4-one 3f

Replace 4-phenyl-1,2,3-thiadiazole 1a in Example 1 with 4-(benzo[d][1,3]dioxol-5-yl)-1,2 , 3-thiadiazole 1e, and the rest is the same as Example 1 to obtain product 3f with a yield of 78%.

Product 3f nuclear magnetic resonance spectrum data: ¹ H NMR (500MHz, CDCl ₃ ) δ6.76-6.72(m,2H),6.69(s,1H),6.68-6.63(m,2H),5.93(s,2H), 3.78 (s, 2H), 2.31 (s, 3H). ¹³ C NMR (126MHz, CDCL ₃ ) Δ182.2,154.8,150.9,148.0,146.9,128.1,127.8,122.2,108.1.1.1.42.2,22. 5 .HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₁₄ H ₁₂ O ₃ S+H ⁺ 261.0580; found:261.0577.

Example 7

Synthesis of 2-benzyl-6-naphthyl-4H-thiopyran-4-one 3g

In Example 3, 4-hydroxy-6-styryl-2H-pyran-2-one 2b is replaced with 4-hydroxy-6-naphthyl-2-ylpyran-2-one 2c. The rest is the same as in Example 3. , 3g of product was obtained, with a yield of 70%.

Nuclear magnetic resonance spectrum data of product 3g: ¹ H NMR (500MHz, CDCl ₃ ) δ8.00-7.95 (m, 1H), 7.88-7.76 (m, 3H), 7.55 (dd, J = 10.0, 1.9Hz, 1H), 7.52-7.46(m,2H),7.31(t,J＝10.0Hz,2H),7.27-7.22(m,3H),7.20-7.16(m,1H),6.89-6.85(m,1H),3.95( s, 2H). ¹³ C NMR (126MHz, CDCl ₃ ) δ182.3,154.9,153.2,136.2,134.0,133.1,132.9,129.2,129.0,128.6,128.4,127.7,127.6,127.1,127.0,126.7,1 23.6,42.9. HRMS-ESI(m/z):[M+H] ⁺ Calcd.for C ₂₂ H ₁₆ OS+H ⁺ 329.0994; found:329.0992.

Comparative example 1

Cesium carbonate was used instead of potassium phosphate in Example 1, and other conditions were the same as Example 1. The selectivity to 3a was 45%.

Comparative example 2

N-methylpyrrolidone was used instead of N,N-dimethylacetamide in Example 1, and other conditions were the same as Example 1. The selectivity to 3a was 40%.

Application Example 1

Synthesis of (E)-2-(2-benzyl-6-(4-(dimethylamino)styryl)-4H-thiopyran-4-ylidene)malononitrile 7a

2-Benzyl-6-methyl-4H-thiopyran-4-one 3a and malononitrile (the specific dosage of both compounds is 0.01 mol, 1:1) were refluxed in acetic anhydride (20 ml) for 3 hours ( The reaction temperature is 139°C), use ethyl acetate to extract acetic anhydride, and then pass through the column with appropriate polarity (petroleum ether: ethyl acetate = 10:1) to obtain 2-(2-benzyl-6-methyl -4H-Thiopyran-4-ylidene)malononitrile 5a. Then 5a used piperidine as the catalyst and p-dimethylaminobenzaldehyde (the dosage of 5a was 0.01mmol, the dosage of piperidine was 20 microliters, and the dosage of p-dimethylaminobenzaldehyde was 0.011mmol) was refluxed in ethanol for 2 days. Spin dry to obtain compound 7a through recrystallization or beating. The yield of product was 77%.

Product 5a structural formula:

Nuclear magnetic resonance spectrum data of product 5a: ¹ H NMR (500MHz, Chloroform-d) δ7.39-7.30 (m, 3H), 7.29 (s, 1H), 7.23 (d, J = 7.0Hz, 2H), 7.17 (s ,1H),3.98(s,2H),2.40(s,3H). ¹³ C NMR(126MHz,Chloroform-d)δ156.81,154.48,150.63,135.70,129.12,128.86,127.90,121.36,121.28,115.13,64.4 8, 43.06,22.99.

Product 7a structural formula:

Nuclear magnetic resonance spectrum data of product 7a: ¹ H NMR (500MHz, Chloroform-d) δ7.44-7.31(m,5H),7.29-7.22(m,2H),7.19(s,1H),7.14(s,1H) ¹³ C NMR(126MHz,Chloroform-d)δ156.67,152.34,151.81,150.63,137.66,136.17,134.52,129.96,129.53,129.26,129.01,127.97,122.46,121.13,119.35,1 19.20,115.91,112.07,63.61,43.52,40.22.

The hydrogen spectrum (1H NMR: 500MHz, CDCl3) of compound 5a is shown in Figure 7, and the carbon spectrum (13CNMR: 126MHz, CDCl3) is shown in Figure 8.

The hydrogen spectrum (1H NMR: 500MHz, CDCl3) of compound 7a is shown in Figure 9, and the carbon spectrum (13CNMR: 126MHz, CDCl3) is shown in Figure 10.

Application Example 2

In Application Example 1, p-dimethylaminobenzaldehyde was replaced with p-hydroxybenzaldehyde, and other conditions were the same as Application Example 1 to obtain compound 7b.

The structural formula of compound 7b:

The UV-visible absorption (UV2600 Shimadzu, Japan) and its fluorescence and excitation spectra (LS 55, PerkinElmer, USA) of compounds 7a, 7b were qualitatively measured.

Use the above instrument to test (E)-2-(2-benzyl-6-(4-(dimethylamino)styryl)-4H-thiopyran-4-ylidene)malononitrile 7a The test results are shown in Figure 11. Compound 7a has a broad absorption from 400nm to 580nm. When the excitation wavelength is 400nm, compound 7a has emission peaks at 510nm and 710nm.

(E)-2-(2-benzyl-6-(4-hydroxystyryl)-4H-thiopyran-4-ylidene)malononitrile 7b was tested in a similar manner, and the results are shown in Figure 12 , Compound 7b has a broad absorption from 350nm to 500nm, and when the excitation wavelength is 400nm, Compound 7b has an emission peak at 730nm. Therefore, the fluorescent probe of the present invention has the characteristics of a wide absorption range, a large Stokes shift, and a long emission wavelength.

Figure 11 is the absorption and emission spectra of compound 7a; Figure 12 is the absorption and emission spectrum of compound 7b.

Figure 13 is an X-ray crystal structure diagram of compound 3b.

Claims (10)

1. An efficient synthesis method of γ-thiopyrone derivatives, characterized in that: comprising the following steps: using a polar organic solvent as a reaction medium, adding a thiadiazole compound and a 4-hydroxypyrone compound in an alkali React under the action of sexual compounds to obtain γ-thiopyrone derivatives; The structural formula of the thiadiazole compound is formula I: R ¹ is H, COOR′, X, OR′, CF ₃ , CN, SR′, R′ is an alkyl group, and naphthyl; or in the structure for/> The structural formula of the 4-hydroxypyrones is formula II: R ² is an aryl group, heterocycle, alkyl group, alkenyl group, or alkynyl group; the aryl group is a phenyl group or a naphthyl group, and the alkenyl group includes a styrene group; The structure of the γ-thiopyrone derivative is formula III: 2. The efficient synthesis method of γ-thiopyrone derivatives according to claim 1, characterized in that: R' is a C _1-5 alkyl group; in R ² , the alkyl group is a C _1-6 alkyl group; The alkaline compound is one or more of cesium carbonate, sodium carbonate, potassium phosphate, potassium carbonate, potassium bicarbonate, and sodium bicarbonate; The polar organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. 3. The efficient synthesis method of γ-thiopyrone derivatives according to claim 2, characterized in that: the alkaline compound is at least one of sodium carbonate, potassium phosphate, and potassium carbonate; The polar organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide. 4. The efficient synthesis method of γ-thiopyrone derivatives according to claim 1, characterized in that: the temperature of the reaction is 60-100°C, and the reaction time is 1-2 days; The molar ratio of the thiadiazole compound and the 4-hydroxypyrone compound is 1:1.1 to 1:1.5. 5. The efficient synthesis method of γ-thiopyrone derivatives according to claim 1, characterized in that: the concentration of the thiadiazole compound in the polar organic solvent is 0.5 ~ 2 mol/L; The molar ratio of the weakly basic salt to the thiadiazole compound is 1: (1.8~2.5); After the reaction is completed, water is extracted, and the crude product is separated by column chromatography. 6. An application of the γ-thiopyrone derivative obtained by the synthesis method according to any one of claims 1 to 5, characterized in that the γ-thiopyrone derivative is used to prepare fluorescent organic compounds. 7. Application according to claim 6, characterized in that: The structure of the fluorescent organic compound is R ³ is H, OH, OR′, N(R′) ₂ , SR′, R′ is alkyl, Ar aryl; R ¹ is H, COOR′, X, OR′, CF ₃ , CN, SR′, R′ is an alkyl group, and naphthyl; or in the structure for/> 8. Application according to claim 7, characterized in that: in ^R3 , the alkyl group is a C _1-4 alkyl group, and the aryl group is phenyl, thiophene, or furan. 9. The application according to claim 7, characterized in that: the preparation method of the fluorescent organic compound includes the following steps: React γ-thiopyranone derivatives with malononitrile to obtain thiopyran compounds containing nitrile groups; react thiopran compounds containing nitrile groups with benzaldehyde compounds to obtain fluorescent compounds; The structure of the γ-thiopyrone derivative is formula III: R ¹ is H, COOR′, X, OR′, CF ₃ , CN, SR′, R′ is an alkyl group, and naphthyl; or in the structure for/> R ² is methyl; The structure of the thiopyran compound containing a nitrile group: The structure of the benzaldehyde compound is R ³ is H, OH, OR', N(R') ₂ , SR', R' is alkyl group, Ar aryl group. 10. The application according to claim 9, characterized in that: in the reaction between the γ-thiopyranone derivative and malononitrile, acetic anhydride is used as the reaction medium; In the reaction between thiopyran compounds containing nitrile groups and benzaldehyde compounds, ethanol is used as the reaction medium and piperidine is used as the catalyst.