A benzothiazole fluorescent probe for detecting cupric chlorate and a preparation method thereof

Abstract

The present invention belongs to the field of fluorescence detection technology, and provides a benzothiazole fluorescent probe for detecting cupric chlorate and a preparation method thereof. The method of the present invention comprises the following steps: 6-iodo-2-methylbenzothiazole, triphenylphosphine palladium, cuprous iodide, triphenylphosphine, 4-ethynyl-N, N-dimethylaniline and triethylamine are reacted, and the obtained N, N'-dimethyl-4-((2-methylbenzo [d] thiazole-6-yl) ethynyl) aniline is reacted with sodium amide and N, N'-dimethylformamide, and the reaction product and p-dimethylaminobenzaldehyde are reacted for a second time to obtain a benzothiazole fluorescent probe. The fluorescent probe PEB-DMA of the present invention can specifically identify cupric chlorate and show an enhanced fluorescence response; the probe PEB-DMA has a certain anti-interference ability, and has a high sensitivity and a low detection limit for low-concentration cupric chlorate detection.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescence detection, and in particular to a benzothiazole fluorescent probe for detecting cupric chlorate and a preparation method thereof. Background Art

[0002] Organic small molecule fluorescent probes have the advantages of good selectivity, high sensitivity, simple operation methods, visual detection and non-invasiveness, and are widely used in cell imaging, biomolecule labeling, enzyme analysis, clinical laboratory diagnosis and environmental analysis. Benzothiazole fluorophores, coumarin fluorophores, tetraphenylethylene fluorophores, triphenylamine fluorophores and rhodamine fluorophores are often used as structural groups of fluorescent dyes. Benzothiazole compounds have high fluorescence quantum yields due to their delocalized large π bonds and rigid planar structures. Therefore, benzothiazole compounds are often widely used as fluorescent groups in fluorescent probes, and such fluorescent probes have been widely used in the fields of biology, environment, and medical testing.

[0003] Copper chlorate, a blue to green, easily deliquescent crystal, is mainly used for dyeing and printing. However, copper chlorate also has certain hazards, such as irritation to the eyes and mucous membranes. Splashing into the eyes can cause conjunctivitis, corneal ulcers, and even contact dermatitis; accidental ingestion can cause acute gastroenteritis; long-term inhalation can cause pulmonary fibrosis. At the same time, copper chlorate is also a dangerous chemical that is easy to make explosives.

[0004] However, there are few reports on the detection methods of copper chlorate. Therefore, it is of great significance to design and synthesize a new benzothiazole fluorescent probe PEB-DMA for effective detection of copper chlorate. Summary of the invention

[0005] The purpose of the present invention is to provide a benzothiazole fluorescent probe for detecting cupric chlorate and a preparation method thereof in order to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a benzothiazole fluorescent probe for detecting cupric chlorate. The structural formula of the benzothiazole fluorescent probe is:

[0008]

[0009] The benzothiazole fluorescent probe is (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline.

[0010] The present invention also provides a method for preparing the benzothiazole fluorescent probe for detecting cupric chlorate, comprising the following steps:

[0011] 1) Concentrated sulfuric acid and concentrated nitric acid are mixed to obtain a mixed acid, 2-methylbenzothiazole is added dropwise to the mixed acid, and after the addition is completed, the reaction system continues to react to obtain 6-nitro-2-methylbenzothiazole;

[0012] 2) reacting 6-nitro-2-methylbenzothiazole, methanol, Raney nickel and hydrazine hydrate under a nitrogen atmosphere to obtain 6-amino-2-methylbenzothiazole;

[0013] 3) mixing 6-amino-2-methylbenzothiazole and hydrochloric acid to obtain a clear solution, sequentially adding a sodium nitrite aqueous solution and a potassium iodide aqueous solution dropwise to the clear solution, and continuing the reaction after the addition is complete to obtain 6-iodo-2-methylbenzothiazole;

[0014] 4) mixing N,N-dimethylaniline, sodium bicarbonate aqueous solution and iodine and reacting them to obtain 4-iodo-N,N-dimethylaniline;

[0015] 5) mixing 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine, triphenylphosphine and trimethylsilylacetylene, and reacting the mixture under a nitrogen atmosphere to obtain N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline;

[0016] 6) mixing N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline and an organic solvent to obtain a clear solution, and reacting the clear solution, sodium fluoride and potassium carbonate under a nitrogen atmosphere to obtain 4-ethynyl-N,N-dimethylaniline;

[0017] 7) mixing 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine, 4-ethynyl-N,N-dimethylaniline and triethylamine and reacting them under a nitrogen atmosphere to obtain N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline;

[0018] 8) Under a nitrogen atmosphere, N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide are reacted, and the reaction product is reacted with p-dimethylaminobenzaldehyde to obtain (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline.

[0019] Preferably, the mass concentration of the concentrated sulfuric acid in step 1) is 97-99%, the mass concentration of the concentrated nitric acid is 65-70%, the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 40-50:20-25; the volume molar ratio of the concentrated sulfuric acid to the 2-methylbenzothiazole is 40-50 mL:125-145 mmol;

[0020] During the dropping process, the temperature of the mixed acid is -5 to 0°C, and the dropping time is 28 to 32 minutes; the temperature of the continued reaction is 22 to 28°C, and the continued reaction time is 1.5 to 2.5 hours.

[0021] Preferably, in step 2), the molar volume ratio of 6-nitro-2-methylbenzothiazole and methanol is 19-22 nmol:45-55 mL; the volume ratio of methanol and hydrazine hydrate is 45-55:8-12; the mass concentration of hydrazine hydrate is 78-82%; and the reaction time is 4-5 h.

[0022] Preferably, in step 3), the molar volume ratio of 6-amino-2-methylbenzothiazole and hydrochloric acid is 10-14 mmol: 22-28 mL; the concentration of hydrochloric acid is 5-7 mol / L, the concentration of sodium nitrite aqueous solution is 0.9-1.1 mol / L, and the concentration of potassium iodide aqueous solution is 0.85-1.0 mol / L; the molar ratio of sodium nitrite to potassium iodide is 14-16: 13-15;

[0023] The mixing temperature is -5 to 0°C; during the process of dropwise adding the sodium nitrite aqueous solution and the potassium iodide aqueous solution, the temperature of the clarified solution is -5 to 0°C; the continued reaction includes a first reaction and a second reaction, the temperature of the first reaction is -5 to 0°C, the time of the first reaction is 0.3 to 0.8h, the temperature of the second reaction is 22 to 28°C, and the time of the second reaction is 1.5 to 2.5h.

[0024] Preferably, in step 4), the molar volume ratio of N,N-dimethylaniline, sodium bicarbonate aqueous solution and iodine is 18-19.5 mmol: 28-32 mL: 15.5-17.2 mmol; the concentration of sodium bicarbonate aqueous solution is 0.9-0.97 mol / L;

[0025] The mixing temperature is ≤10°C; the reaction temperature is 22-28°C, and the reaction time is 0.5-1h.

[0026] Preferably, in step 5), the molar ratio of 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and trimethylsilyl acetylene is 11-13: 0.3-0.36: 0.65-0.8: 0.08-0.1: 28-32; the molar volume ratio of tetrakistriphenylphosphine palladium and triethylamine is 0.3-0.36 mmol: 45-55 mL; the reaction temperature is 22-28° C., and the reaction time is 11-13 h.

[0027] Preferably, in step 6), the molar volume ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline to the organic solvent is 4-5.2 mmol:37-43 mL; the organic solvent is methanol and tetrahydrofuran, and the volume ratio of methanol to tetrahydrofuran is 0.8-1.2:0.8-1.2; the molar ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline, sodium fluoride and potassium carbonate is 4-5.2:1.05-1.25:1.05-1.25;

[0028] The reaction temperature is 37-43° C., and the reaction time is 3.5-4.5 h.

[0029] Preferably, in step 7), the molar ratio of 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and 4-ethynyl-N,N-dimethylaniline is 1.76-1.86: 0.013-0.023: 0.08-0.1: 0.08-0.1: 2.07-2.27; the molar volume ratio of tetrakistriphenylphosphine palladium and triethylamine is 0.013-0.023 mmol: 28-32 mL;

[0030] The reaction temperature is 22-28° C., and the reaction time is 11-13 hours.

[0031] Preferably, in step 8), the molar volume ratio of N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide is 0.63-0.73 mmol: 0.9-1.1 mmol: 28-32 mL; the molar ratio of sodium amide and p-dimethylaminobenzaldehyde is 0.9-1.1: 0.9-1.1;

[0032] The reaction time is 0.8 to 1.2 hours; the second reaction time is 46 to 50 hours.

[0033] The beneficial effects of the present invention include:

[0034] The present invention uses 2-methylbenzothiazole as a parent nucleus to prepare a new benzothiazole fluorescent probe PEB-DMA. Since electron-donating structures are introduced on both sides of 2-methylbenzothiazole, a large "push-pull-push" conjugated system is formed, so that the fluorescence emission spectrum of the probe PEB-DMA is red-shifted compared with the emission spectrum of benzothiazole, and the probe PEB-DMA has a large Stokes shift of 90nm. The probe PEB-DMA can specifically identify cupric chlorate and show an enhanced fluorescence response; through ion competition experiments, it is found that in the presence of interfering ions, the fluorescence response of the probe PEB-DMA will be slightly affected, but the fluorescence is still significantly increased, indicating that the probe has a certain anti-interference ability. The probe PEB-DMA has high sensitivity and low detection limit for low-concentration cupric chlorate detection, and provides a simple method for the detection of cupric chlorate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The UV-visible absorption spectra of the probe of Example 1 in different solvents;

[0036] Figure 2 are the excitation wavelength and emission wavelength of the probe in Example 1 in tetrahydrofuran solution;

[0037] Figure 3 The fluorescence effect of the probe of Example 1 in different solvents;

[0038] Figure 4 is the selectivity of the probe of Example 1 to metal cations, wherein a is a spectrum graph and b is a bar graph;

[0039] Figure 5 The selectivity of the probe of Example 1 to different copper salts, wherein a is a spectrum graph and b is a bar graph;

[0040] Figure 6 is the fluorescence emission spectrum of the probe of Example 1 to potassium chlorate and copper chlorate;

[0041] Figure 7 is the UV-visible absorption spectrum of the probe of Example 1 and cupric chlorate;

[0042] Figure 8 The Job's curve spectrum (a) and Job's curve (b) of the probe of Example 1 and cupric chlorate;

[0043] Fig. 9 This is the mass spectrum of the probe PEB-DMA of Example 1 coordinated with copper chlorate in a molar ratio of 1:1;

[0044] Fig.10 The infrared spectra of the probe in Example 1 before and after the reaction with cupric chlorate;

[0045] Fig.11 The ultraviolet absorption spectrum of cupric chlorate and the fluorescence excitation spectrum of the probe PEB-DMA in Example 1;

[0046] Fig.12 This is the anti-interference test of the probe PEB-DMA of Example 1 on metal ions;

[0047] Fig.13 The fluorescence titration spectra of the probe of Example 1 to different concentrations of cupric chlorate;

[0048] Fig.14 The titration fitting curve diagram (a) and the titration linear regression diagram (b) of the probe of Example 1 on cupric chlorate;

[0049] Fig.15 The color change of the probe in Example 1 before and after the reaction with copper chlorate. DETAILED DESCRIPTION

[0050] The present invention provides a benzothiazole fluorescent probe for detecting cupric chlorate. The structural formula of the benzothiazole fluorescent probe is:

[0051]

[0052] The benzothiazole fluorescent probe is (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline.

[0053] The present invention also provides a method for preparing the benzothiazole fluorescent probe for detecting cupric chlorate, comprising the following steps:

[0054] 1) Concentrated sulfuric acid and concentrated nitric acid are mixed to obtain a mixed acid, 2-methylbenzothiazole (compound A) is added dropwise to the mixed acid, and after the addition is completed, the reaction system continues to react to obtain 6-nitro-2-methylbenzothiazole (compound B);

[0055] 2) reacting 6-nitro-2-methylbenzothiazole, methanol, Raney nickel and hydrazine hydrate under a nitrogen atmosphere to obtain 6-amino-2-methylbenzothiazole (compound C);

[0056] 3) mixing 6-amino-2-methylbenzothiazole and hydrochloric acid to obtain a clear solution, sequentially adding a sodium nitrite aqueous solution and a potassium iodide aqueous solution dropwise to the clear solution, and continuing the reaction after the addition is complete to obtain 6-iodo-2-methylbenzothiazole (compound D);

[0057] 4) mixing N,N-dimethylaniline (compound E), sodium bicarbonate aqueous solution and iodine and reacting them to obtain 4-iodo-N,N-dimethylaniline (compound F);

[0058] 5) mixing 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine, triphenylphosphine and trimethylsilylacetylene, and reacting the mixture under a nitrogen atmosphere to obtain N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline (Compound G);

[0059] 6) mixing N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline and an organic solvent to obtain a clear solution, and reacting the clear solution, sodium fluoride and potassium carbonate under a nitrogen atmosphere to obtain 4-ethynyl-N,N-dimethylaniline (compound H);

[0060] 7) mixing 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine, 4-ethynyl-N,N-dimethylaniline and triethylamine and reacting them under a nitrogen atmosphere to obtain N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline (Compound I);

[0061] 8) Under a nitrogen atmosphere, N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide are reacted, and the reaction product is reacted with p-dimethylaminobenzaldehyde to obtain (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline (PEB-DMA).

[0062] In the present invention, the synthesis route of (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline (PEB-DMA) is as follows:

[0063]

[0064] In the present invention, the mass concentration of the concentrated sulfuric acid in step 1) is preferably 97-99%, more preferably 97.5-98.5%, and more preferably 98%; the mass concentration of concentrated nitric acid is preferably 65-70%, more preferably 67-69%, and more preferably 68%; the volume ratio of concentrated sulfuric acid to concentrated nitric acid is preferably 40-50:20-25, more preferably 42-48:21-23, and more preferably 44-45:22; the volume molar ratio of concentrated sulfuric acid to 2-methylbenzothiazole is preferably 40-50 mL:125-145 mmol, more preferably 42-48 mL:130-140 mmol, and more preferably 44-45 mL:134-135 mmol.

[0065] In the present invention, during the dropwise addition in step 1), the temperature of the mixed acid is preferably -5 to 0°C, more preferably -4 to -1°C, and more preferably -3 to -2°C; the dropwise addition time is preferably 28 to 32 min, more preferably 29 to 31 min, and more preferably 30 min; the temperature for continued reaction is preferably 22 to 28°C, more preferably 24 to 26°C, and more preferably 25°C; the time for continued reaction is preferably 1.5 to 2.5 h, and more preferably 2 h.

[0066] In the present invention, the molar volume ratio of 6-nitro-2-methylbenzothiazole and methanol in step 2) is preferably 19-22nmol:45-55mL, more preferably 20-21nmol:48-52mL, more preferably 20.6nmol:50mL; the volume ratio of methanol and hydrazine hydrate is preferably 45-55:8-12, more preferably 48-52:9-11, more preferably 50:10; the mass concentration of hydrazine hydrate is preferably 78-82%, more preferably 79-81%, more preferably 80%; the reaction time is preferably 4-5h, more preferably 4.5h.

[0067] In the present invention, the molar volume ratio of 6-amino-2-methylbenzothiazole and hydrochloric acid in step 3) is preferably 10-14 mmol: 22-28 mL, more preferably 11-13 mmol: 24-26 mL, and more preferably 12 mmol: 25 mL; the concentration of hydrochloric acid is preferably 5-7 mol / L, more preferably 5.5-6.5 mol / L, and more preferably 6 mol / L; the concentration of the sodium nitrite aqueous solution is preferably 0.9-1.1 mol / L, and more preferably 1 mol / L; the concentration of the potassium iodide aqueous solution is preferably 0.85-1.0 mol / L, and more preferably 0.88-0.95 mol / L, and more preferably 0.9-0.93 mol / L; the molar ratio of sodium nitrite to potassium iodide is preferably 14-16: 13-15, and more preferably 14.5-15.5: 13.5-14.5, and more preferably 15: 14.

[0068] In the present invention, the mixing temperature in step 3) is preferably -5 to 0°C, more preferably -4 to -1°C, and more preferably -3 to -2°C; during the dropwise addition of the sodium nitrite aqueous solution and the potassium iodide aqueous solution, the temperature of the clear solution is preferably -5 to 0°C, more preferably -4 to -1°C, and more preferably -3 to -2°C; the continued reaction includes a first reaction and a second reaction, the temperature of the first reaction is preferably -5 to 0°C, more preferably -4 to -1°C, and more preferably -3 to -2°C, the time of the first reaction is preferably 0.3 to 0.8h, and more preferably 0.5h; the temperature of the second reaction is preferably 22 to 28°C, more preferably 24 to 26°C, and more preferably 25°C; the time of the second reaction is preferably 1.5 to 2.5h, and more preferably 2h.

[0069] In the present invention, in step 3), during the process of adding the sodium nitrite aqueous solution dropwise, the potassium iodide aqueous solution is added dropwise after the diazonium salt is generated in the TLC monitoring system.

[0070] In the present invention, the molar volume ratio of N,N-dimethylaniline, sodium bicarbonate aqueous solution and iodine in step 4) is preferably 18-19.5 mmol: 28-32 mL: 15.5-17.2 mmol, more preferably 18.5-19 mmol: 29-31 mL: 16-17 mmol, more preferably 18.7-18.8 mmol: 30 mL: 16.5-16.7 mmol; the concentration of sodium bicarbonate aqueous solution is preferably 0.9-0.97 mol / L, more preferably 0.92-0.95 mol / L, more preferably 0.93-0.94 mol / L;

[0071] The mixing temperature is preferably ≤10°C, more preferably ≤8°C; the reaction temperature is preferably 22-28°C, more preferably 24-26°C, more preferably 25°C; the reaction time is preferably 0.5-1h, more preferably 0.8h.

[0072] In the present invention, the molar ratio of 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and trimethylsilyl acetylene in step 5) is preferably 11-13: 0.3-0.36: 0.65-0.8: 0.08-0.1: 28-32, more preferably 11.5-12.5: 0.32-0.34: 0.68-0.75: 0.085-0.095: 29-31, more preferably 12: 0.33: 0.7-0.72: 0 .09:30; the molar volume ratio of tetrakistriphenylphosphine palladium and triethylamine is preferably 0.3-0.36mmol:45-55mL, more preferably 0.32-0.34mmol:48-52mL, more preferably 0.33mmol:50mL; the reaction temperature is preferably 22-28°C, more preferably 24-26°C, more preferably 25°C; the reaction time is preferably 11-13h, more preferably 11.5-12.5h, more preferably 12h.

[0073] In the present invention, the molar volume ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline and the organic solvent in step 6) is preferably 4-5.2mmol:37-43mL, more preferably 4.3-5mmol:39-41mL, and more preferably 4.5-4.6mmol:40mL; the organic solvent is preferably methanol and tetrahydrofuran, and the volume ratio of methanol and tetrahydrofuran is preferably 0.8-1.2:0.8-1.2, and more preferably 1:1; the molar ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline, sodium fluoride and potassium carbonate is preferably 4-5.2:1.05-1.25:1.05-1.25, and more preferably 4.3-5:1.1-1.2:1.1-1.2, and more preferably 4.5-4.6:1.15:1.15;

[0074] The reaction temperature is preferably 37-43° C., more preferably 39-41° C., and more preferably 40° C.; the reaction time is preferably 3.5-4.5 h, and more preferably 4 h.

[0075] In the present invention, the molar ratio of 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and 4-ethynyl-N,N-dimethylaniline in step 7) is preferably 1.76-1.86: 0.013-0.023: 0.08-0.1: 0.08-0.1: 2.07-2.27, and more preferably 1.79-1.82: 0.016-0.021: 0.085-0.095: 0.085- 0.095:2.12-2.22, more preferably 1.8-1.81:0.018-0.019:0.09:0.09:2.17-2.18; the molar volume ratio of tetrakistriphenylphosphine palladium to triethylamine is preferably 0.013-0.023mmol:28-32mL, more preferably 0.016-0.021mmol:29-31mL, more preferably 0.018-0.019mmol:30mL;

[0076] The reaction temperature is preferably 22 to 28° C., more preferably 24 to 26° C., and more preferably 25° C.; the reaction time is preferably 11 to 13 h, more preferably 11.5 to 12.5 h, and more preferably 12 h.

[0077] In the present invention, the molar volume ratio of N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide in step 8) is preferably 0.63-0.73 mmol: 0.9-1.1 mmol: 28-32 mL, more preferably 0.66-0.7 mmol: 0.95-1.05 mmol: 29-31 mL, more preferably 0.68-0.69 mmol: 1.0 mmol: 30 mL; the molar ratio of sodium amide and p-dimethylaminobenzaldehyde is preferably 0.9-1.1: 0.9-1.1, more preferably 0.95-1.05: 0.95-1.05, more preferably 1:1;

[0078] The reaction time is preferably 0.8 to 1.2 h, more preferably 1 h; the second reaction time is preferably 46 to 50 h, more preferably 47 to 49 h, more preferably 48 h.

[0079] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0080] Example 1

[0081] (1) Synthesis of 6-nitro-2-methylbenzothiazole (Compound B)

[0082] 44mL of concentrated sulfuric acid (mass concentration of 98%) was dripped into a two-necked bottle containing 22mL of concentrated nitric acid (mass concentration of 68%) at constant pressure (1min / drop), and the system temperature was maintained at -2°C. Then, 134mmol of 2-methylbenzothiazole was dripped into the system through a constant pressure dropping funnel. The system temperature was maintained at -2°C during this process. After 30min, all 2-methylbenzothiazole was added to the system. Then, the system was heated to 25°C and the reaction was continued for 2h. During this process, the reaction progress of the system was monitored by thin layer chromatography (TLC) until the raw materials were completely reacted. After the reaction, the reaction product was poured into 500 g of ice water and stirred continuously with a glass rod, and a light yellow solid was precipitated. The reaction system was then filtered under reduced pressure (-0.01 MPa), the filter cake was slurried with anhydrous ethanol for 15 min, and filtered under reduced pressure again. Finally, the filter cake was vacuum dried at 40 ° C (vacuum degree was -0.01 MPa) to obtain 13.0 g of compound B with a yield of 50%. The melting range was measured: 1667.1-167.4 ° C, MS (ESI +) m / z = 195.1 (M + H), MS (ESI +) m / z = 236.1 (M + H + acetonitrile), NMR: 1 H NMR (400MHz, CDCl3) δ8.76(d,J=2.1Hz,1H),8.32(dd,J=8.9,2.2Hz,1H),8.02(d,J=9.0Hz,1H),2.92(s,3H). 13 C NMR (101MHz, CDCl3) δ173.30,157.13,144.77,136.04,122.63,121.53,117.98,20.67.

[0083] (2) Synthesis of 6-amino-2-methylbenzothiazole (Compound C)

[0084] Dissolve 20.6 nmol of compound B in 50 mL of anhydrous methanol, add 1 teaspoon of Raney nickel, add 10 mL of hydrazine hydrate (mass concentration 80%) to the reaction system, and react under nitrogen protection. During the whole process, TLC monitors the progress of the reaction. After the system reacts for 4 hours, the raw materials react completely. Then, the system is filtered under reduced pressure, the filtrate is concentrated, and dried over anhydrous magnesium sulfate to obtain 2.5 g of compound C with a yield of 74%. Melting range: 124.9-125.1°C, MS (ESI+) m / z=165.15 (M+H), NMR: 1 H NMR (400MHz, CDCl3) δ7.88–7.56(m,1H),7.02(d,J=2.3Hz,1H),6.76(dd,J=8.6,2.3Hz,1H),3.66(s,2H),2.73(s,3H). 13C NMR (101MHz, CDCl3) δ162.66,146.69,144.11,137.24,122.68,115.18,105.83,19.82.

[0085] (3) Synthesis of 6-iodo-2-methylbenzothiazole (Compound D)

[0086] At -2°C, 12mmol of compound C was dissolved in 25mL of hydrochloric acid (concentration of 6mol / L), and stirred until the system was clear. 15mol of NaNO2 was dissolved in 15mL of water, and then added dropwise at constant pressure (20s / drop) to the system. After TLC monitoring showed that diazonium salt was generated in the system, 14mmol of KI was dissolved in 15mL of water, and then added dropwise to the reaction system at constant pressure. The system temperature was maintained at -2°C. After reacting for 0.5h, the temperature was raised to 25°C and the reaction was continued for 2h. The reaction progress of the system was monitored by TLC during the whole process. After the raw material reacted completely, it was extracted with 300mL of dichloromethane three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography using petroleum ether and ethyl acetate in a volume ratio of 100:1 to obtain 850mg of compound D. Melting range: 140.3~140.4℃, MS (ESI+) m / z=165.15(M+H)275.95, NMR: 1 HNMR (400MHz, CDCl3) δ8.14 (d, J = 1.2 Hz, 1H), 7.70 (dt, J = 18.5, 5.0 Hz, 2H), 2.82 (s, 3H). 13 CNMR (101MHz, CDCl3) δ167.55,152.77,137.79,135.01,129.89,123.91,88.92,20.06.

[0087] (4) Synthesis of 4-iodo-N,N-dimethylaniline (Compound F)

[0088] 18.7mmol N,N-dimethylaniline and 30mL sodium bicarbonate aqueous solution (concentration of 0.95mol / L) were added to a 100mL two-necked flask, the system temperature was maintained at 9°C, and then 16.5mmol I2 was added to the system in 25 times (about 1h). After all I2 was added, the temperature was raised to 25°C and reacted for 0.5h. The reaction progress was monitored by TLC. After the raw materials reacted, 70mL of water was added to the system to quench the reaction, and the system was extracted with 300mL of ethyl acetate three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 3.8g of crude product, which was purified by column chromatography with petroleum ether to obtain 3.4g of compound F with a yield of 74%, melting range: 74.8-75.4°C, MS (ESI+) m / z=248.05 (M+H), NMR: 1 HNMR (400MHz, CDCl3) δ8.13(d,J=8.2Hz,1H),7.78(d,J=8.0Hz,1H),7.50(dd,J=8.0,7.4Hz,1H),7.41(t,J=7.6Hz,1H),2.95(s,3H),2.87(s,3H). 13 C NMR (101MHz, CDCl3) δ181.12,169.43,150.54,133.53,126.97,125.95,122.77,121.64,29.72,20.73.

[0089] (5) Synthesis of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline (Compound G)

[0090] 12mmol of compound F, 0.33mmol of tetrakistriphenylphosphine palladium, and 0.72mmol of cuprous iodide were dissolved in 50mL of anhydrous triethylamine, and then 0.09mmol of triphenylphosphine and 30mmol of trimethylsilyl acetylene were added to the system, and the reaction was carried out under nitrogen protection at 25°C for 12h. The progress of the reaction was monitored by TLC during the whole process. After the reaction of the raw materials was completed, 300mL of water was added to the system to quench the reaction, and 300mL of ethyl acetate was used to extract the system three times. The organic phases were combined, washed with saturated brine, dried with anhydrous sodium sulfate, and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography with petroleum ether to obtain 1.8g of compound G, with a yield of 69%. Melting range: 85.8-86.4°C, MS (ESI+) m / z=218.25 (M+H), NMR: 1 H NMR (400MHz, CDCl3) δ7.54–7.33(m,2H),6.62(d,J=8.9Hz,2H),2.99(s,6H),0.26(d,J=3.3Hz,9H). 13C NMR (101MHz, CDCl3) δ150.25,133.18,111.66,109.96,106.62,91.24,40.23,0.28.

[0091] (6) Synthesis of 4-ethynyl-N,N-dimethylaniline (Compound H)

[0092] 4.6mmol of compound G was dissolved in 40mL of organic solvent (the volume ratio of methanol to tetrahydrofuran was 1:1). After the system was stirred until clear, 1.15mmol of sodium fluoride and 1.15mmol of potassium carbonate were added. The reaction system was heated to 40°C under nitrogen protection for 4h. The reaction progress was monitored by TLC. After the reaction of the raw materials was completed, 100mL of water was added to the system to quench the reaction. Then, the system was extracted with 300mL of ethyl acetate three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 600mg of compound H with a yield of 90%. MS (ESI+) m / z 146.15 (M+H), NMR: 1 H NMR (400MHz, CDCl3) δ7.40-7.37(m,1H),7.37-7.34(m,1H),6.66-6.62(m,1H),6.61(d,J=2.1Hz,1H),2.98(d,J=4.8Hz,6H). 13 C NMR (101MHz, CDCl3) δ150.41,133.22,111.71,108.76,84.89,74.80,40.19.

[0093] (7) Synthesis of N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline (Compound I)

[0094] 1.81mmol of compound D, 0.018mmol of tetrakistriphenylphosphine palladium and 0.09mmol of cuprous iodide were dissolved in 30mL of anhydrous triethylamine. 0.09mmol of triphenylphosphine and 2.17mmol of compound H were added to the system. The reaction was carried out under nitrogen protection for 12h. The progress of the reaction was monitored by TLC during the whole process. After the reaction of the raw materials was completed, 100mL of water was added to the system to quench the reaction. Then, 300mL of ethyl acetate was used to extract the reaction system three times. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 800mg of crude product. The crude product was purified by column chromatography (the volume ratio of petroleum ether to ethyl acetate was 30:1) to obtain 550mg of compound I with a yield of 82%. The melting range was 147.7-148.8℃, MS (ESI+) m / z=293.15 (M+H), NMR: 1H NMR (400MHz, CDCl3) δ7.95(d,J=1.0Hz,1H),7.87(d,J=8.4Hz,1H),7.56(dd,J=8.4, 1.5Hz,1H),7.42(d,J=8.8Hz,2H),6.67(d,J=8.8Hz,2H),3.00(s,6H),2.83(s,3H). 13 C NMR (101MHz, CDCl3) δ167.72,152.49,150.27,135.79,133.64,132.75,129.36,12 4.09,122.08,120.84,111.78,109.81,108.66,91.23,87.07,82.38,40.18,20.20.

[0095] (8) Synthesis of (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline (PEB-DMA)

[0096] 0.68mmol of compound I was dissolved in 30mL of anhydrous N,N-dimethylformamide, 1.0mmol of sodium amide was added, and the reaction was carried out under nitrogen protection for 1h. 1.0mmol of p-dimethylaminobenzaldehyde was added to the system and the reaction was carried out under nitrogen protection. The reaction progress was monitored by TLC during the whole process. After 48h of reaction, the raw materials were reacted. 50mL of NH4Cl saturated solution was added to the system to quench the reaction, and then the system was poured into 400mL of water, and then 300mL of dichloromethane was used to extract the system three times. The organic phases were combined, washed with saturated brine, dried with anhydrous sodium sulfate, and concentrated under reduced pressure to obtain a crude product, which was first slurried with acetonitrile, and then purified by column chromatography (the volume ratio of petroleum ether and ethyl acetate was 5:1) to obtain 58mg of probe PEB-DMA. MS (ESI+) m / z = 424.3 (M+H), NMR: 1 H NMR (400MHz, CDCl3) δ7.95 (s, 1H), 7.85 (d, J = 8.4Hz, 1H), 7.55 (dd, J = 8.4, 1.5Hz, 1H), 7.48 (d, J = 8.9Hz, 2H),7.45–7.40(m,2H),7.21(s,1H),7.17(s,1H),6.70(dd,J=15.8,8.8Hz,4H),3.02(d,J=11.9Hz,12H).

[0097] Example 2

[0098] The system temperature of step (1) in Example 1 was changed from -2°C to 0°C, the volumes of concentrated sulfuric acid and concentrated nitric acid were 42 mL and 21 mL respectively, the amount of 2-methylbenzothiazole was 130 mmol, and the reaction time was continued for 1.5 h;

[0099] In step (2), the amount of compound B is 20 nmol, the amount of methanol is 48 mL, and the amount of hydrazine hydrate is 9 mL;

[0100] In step (3), -2°C is replaced by 0°C, the compound C is 11 mmol, the concentration of hydrochloric acid is 5.5 mol / L, the concentration of the sodium nitrite aqueous solution is 0.9 mol / L, and the concentration of the KI aqueous solution is 0.95 mol / L;

[0101] In step (4), the amount of N,N-dimethylaniline is 19 mmol, the concentration of the sodium bicarbonate aqueous solution is 0.93 mol / L, and the amount of I2 is 16 mmol;

[0102] In step (5), the compound F is 11.5 mmol, tetrakistriphenylphosphine palladium is 0.3 mmol, cuprous iodide is 0.68 mmol, triphenylphosphine is 0.085 mmol, and trimethylsilyl acetylene is 29 mmol;

[0103] In step (6), the amount of compound G is 4.3 mmol, the amount of sodium fluoride is 1.1 mmol, the amount of potassium carbonate is 1.1 mmol, the reaction temperature is 39° C., and the reaction time is 4.5 h;

[0104] In step (7), the amount of compound D is 1.79 mmol, the amount of tetrakistriphenylphosphine palladium is 0.016 mmol, the amount of cuprous iodide is 0.085 mmol, the amount of triphenylphosphine is 0.085 mmol, and the amount of compound H is 2.12 mmol;

[0105] In step (8), the amount of compound I is 0.66 mmol, the amount of sodium amide is 0.95 mmol, the amount of p-dimethylaminobenzaldehyde is 0.95 mmol, and the reaction time is 47 h.

[0106] Example 3

[0107] The system temperature of step (1) in Example 1 was changed from -2°C to -4°C, the volumes of concentrated sulfuric acid and concentrated nitric acid were 48 mL and 23 mL respectively, the amount of 2-methylbenzothiazole was 140 mmol, and the reaction time was continued for 2.5 h;

[0108] In step (2), the amount of compound B is 21 nmol, the amount of methanol is 52 mL, and the amount of hydrazine hydrate is 11 mL;

[0109] In step (3), -2°C is replaced by -4°C, the compound C is 13 mmol, the concentration of hydrochloric acid is 6.5 mol / L, the concentration of sodium nitrite aqueous solution is 1.1 mol / L, and the concentration of KI aqueous solution is 0.9 mol / L;

[0110] In step (4), the amount of N,N-dimethylaniline is 18.5 mmol, the concentration of the sodium bicarbonate aqueous solution is 0.97 mol / L, and the amount of I2 is 17 mmol;

[0111] In step (5), the compound F is 12.5 mmol, tetrakistriphenylphosphine palladium is 0.3 mmol, cuprous iodide is 0.75 mmol, triphenylphosphine is 0.095 mmol, and trimethylsilyl acetylene is 31 mmol;

[0112] In step (6), the compound G is 5 mmol, the sodium fluoride is 1.2 mmol, the potassium carbonate is 1.2 mmol, the reaction temperature is 43°C, and the reaction time is 3.5 h;

[0113] In step (7), the amount of compound D is 1.86 mmol, the amount of tetrakistriphenylphosphine palladium is 0.021 mmol, the amount of cuprous iodide is 0.095 mmol, the amount of triphenylphosphine is 0.095 mmol, and the amount of compound H is 2.22 mmol;

[0114] In step (8), the amount of compound I is 0.7 mmol, the amount of sodium amide is 1.05 mmol, the amount of p-dimethylaminobenzaldehyde is 1.05 mmol, and the reaction time is 49 h.

[0115] The probe PEB-DMA of Example 1 was dissolved in anhydrous ethanol or tetrahydrofuran to obtain a mother solution with a concentration of 0.001 mol / L, and a spectral test was performed, wherein the fluorescence data was measured by a Perkin Elmer LS-55 fluorescence spectrophotometer; the ultraviolet absorption spectrum data was measured by a UV-visible spectrophotometer Lambda950.

[0116] (1) UV absorption solvent effect of probe

[0117] 150 μL of the mother solution with a concentration of 0.001 mol / L prepared with anhydrous ethanol was dissolved in anhydrous ethanol, tetrahydrofuran, acetonitrile, 1,4-dioxane, acetone, ethyl acetate, methanol, water, N,N-dimethylformamide, and dimethyl sulfoxide (the probe concentration in each solvent was 7.5×10 -5 mol / L), the UV-visible absorption spectra of the probe PEB-DMA of Example 1 in different solvents are as follows Figure 1 As shown by Figure 1It can be seen that due to the dual influence of the conjugated structure of the probe PEB-DMA and the polarity of the organic reagent, the probe has the highest absorbance in tetrahydrofuran solution, with the maximum absorption peak at 418 nm.

[0118] (2) Fluorescence properties of the probe PEB-DMA

[0119] 2mL of 0.001mol / L mother solution prepared with tetrahydrofuran was tested for excitation wavelength and emission wavelength (Slit: 8*8, Scan: 500). The results are as follows: Figure 2 As shown. Figure 2 It can be seen that the excitation wavelength (EX) of the probe PEB-DMA of Example 1 is 418-421 nm, the emission wavelength (Em) is 509-511 nm, and the Stokes shift of the probe is as high as about 90 nm. Stokes shift refers to the difference between the excitation wavelength peak and the emission wavelength peak. Generally, a smaller Stokes shift refers to a difference of ≤50 nm, which often means that the fluorescence excitation spectrum and the emission spectrum of the probe partially overlap, resulting in a poor signal-to-noise ratio; the Stokes shift of the probe PEB-DMA of the present invention is 90 nm, which is higher than 50 nm, proving that the probe can prevent the spectral overlap between the excitation spectrum and the emission spectrum, thereby effectively avoiding the self-quenching phenomenon during the test process.

[0120] (3) Fluorescence properties of the probe in different solvents

[0121] 10 μL of the mother solution prepared with tetrahydrofuran at a concentration of 0.001 mol / L was dissolved in 2 mL of tetrahydrofuran, dimethyl sulfoxide, piperidine, toluene, N,N-dimethylformamide, water, methanol, ethanol, ethyl acetate, acetone, acetonitrile, and 1,4-dioxane, respectively, and the fluorescence test (E X =420nm, Slit:8*8, Scan:500), the fluorescence effect of the probe of Example 1 in different solvents is as follows Figure 3 As shown. Figure 3 It can be seen that the fluorescence response of the probe PEB-DMA is the strongest in tetrahydrofuran. At the same time, the test results show that the fluorescence intensity of the probe decreases with the increase of the acidity of the solvent, especially with the increase of the protonation degree of the solvent, the higher the degree of quenching of the probe fluorescence intensity, and even completely quenched in water.

[0122] (4) Probe recognition of metal ions and non-metal ions

[0123] The probe PEB-DMA of Example 1 was dissolved in tetrahydrofuran to obtain a concentration of 1×10 -3 mol / L mother solution; dilute 2mL of the mother solution to 200mL with tetrahydrofuran to obtain 1×10 -5mol / L probe solution.

[0124] 20 μL of different metal cation solutions with a concentration of 0.01 mol / L were added to 2 mL of the probe solution, and the corresponding fluorescence emission spectra (E X =420nm, Slit:8*8, Scan:500), the selectivity of the probe of Example 1 to metal cations is as follows Figure 4 As shown, a is the spectrum graph and b is the bar graph. Figure 4 It can be seen that under the excitation wavelength of 420nm, the probe PEB-DMA has a strong fluorescence emission peak at 510nm. When 20μL of copper chlorate aqueous solution (0.01mol / L) is added to 2mL of the probe PEB-DMA solution, the probe molecule emits a peak fluorescence intensity at 510nm that increases significantly, while other metal ion fluorescence emission spectra do not have this phenomenon. The experimental results show that the probe PEB-DMA has a good recognition effect on copper chlorate.

[0125] To 2mL concentration of 1×10 -5 20 μL of different copper salt solutions (copper chlorate, copper chloride, copper nitrate, copper sulfate, copper acetate) with a concentration of 0.01 mol / L were added to the 1.5 mol / L probe solution, and the corresponding fluorescence emission spectra were tested. The results are as follows: Figure 5 As shown, a is the spectrum graph and b is the bar graph. Figure 5 It can be seen that under the same conditions, the probe PEB-DMA has a significantly enhanced fluorescence response to copper chlorate, which is speculated to be the result of the binding of chlorate to the probe, thereby enhancing the fluorescence.

[0126] To 2mL concentration of 1×10 -5 20 μL of 0.01 mol / L potassium chlorate aqueous solution or copper chlorate aqueous solution was added to the 0.01 mol / L probe solution, and the corresponding fluorescence emission spectra were tested. The results are as follows: Figure 6 As shown by Figure 6 It can be seen that there is no obvious fluctuation in the fluorescence intensity of the probe after adding potassium chlorate, from which it can be inferred that the probe PEB-DMA can specifically recognize copper chlorate.

[0127] (5) Mechanism of action between probe and cupric chlorate

[0128] The probe PEB-DMA of Example 1 was dissolved in tetrahydrofuran to obtain a concentration of 1×10 -3 mol / L mother solution; dilute 2mL of the mother solution to 200mL with tetrahydrofuran to obtain 1×10 -5 mol / L probe solution.

[0129] The UV-visible absorption spectra and Job's curves of the probe and cupric chlorate were tested (EX =420nm, Slit:8*8, Scan:500). The UV-visible absorption spectra of the probe of Example 1 and cupric chlorate are as follows: Figure 7 As shown, Job's curve is as follows Figure 8 As shown, a is the spectrum diagram and b is the curve diagram.

[0130] from Figure 7 It can be seen that with the increase of cupric chlorate concentration, the absorption intensity of the UV-visible absorption spectrum of the probe PEB-DMA at 422nm is significantly enhanced. The molar extinction coefficients (ε) of the probe PEB-DMA and PEB-DMA+Cu(ClO3)2 are calculated by the Beer-Lambert law, which are 3.8×10 3 M -1 cm -1 and 5.7×10 3 M -1 cm -1 The increased absorption intensity at 422 nm and the more significant molar extinction coefficient of the PEB-DMA+Cu(ClO3)2 system are due to the interaction between the probe PEB-DMA and cupric chlorate. Control [PEB-DMA] + [Cu(ClO3)2] = 1 × 10 -5 M is constant, [Cu(ClO3)2] / {[PEB-DMA]+[Cu(ClO3)2]} is used as the variable, and the fluorescence intensity is used as the dependent variable to draw the Job's plot curve, such as Figure 8 As shown, the experimental results show that when [Cu(ClO3)2] / {[PEB-DMA]+[Cu(ClO3)2]}≈0.5, an inflection point appears in the Job's plot curve, indicating that the probe PEB-DMA binds to copper chlorate in a molar ratio of 1:1.

[0131] The mass spectrum of the probe PEB-DMA in Example 1 coordinated with copper chlorate in a molar ratio of 1:1 is shown in Fig. 9 As shown in the figure, MS (ESI-) m / z = 653.17, which is consistent with the theoretical value of 654.01, which can further prove that the probe PEB-DMA is combined with copper chlorate in a molar ratio of 1:1.

[0132] The infrared spectra of the probe PEB-DMA of Example 1 and the probe PEB-DMA combined with copper chlorate at a molar ratio of 1:1 are shown in FIG. Fig.10 As shown by Fig.10 It can be seen that after the probe PEB-DMA combined with copper chlorate in a 1:1 ratio, the position of the characteristic peak of the probe PEB-DMA did not change, proving that the interaction between the probe PEB-DMA and copper chlorate did not cause changes in the functional groups of the probe PEB-DMA.

[0133] The ultraviolet absorption spectrum of cupric chlorate and the fluorescence excitation spectrum of the probe PEB-DMA in Example 1 are as follows: Fig.11 As shown by Fig.11 It can be seen that there is almost no overlap between the ultraviolet absorption spectrum of cupric chlorate and the fluorescence excitation spectrum of the probe PEB-DMA, which proves that there is no competitive absorption between the probe PEB-DMA and cupric chlorate.

[0134] (6) Anti-interference performance of the probe

[0135] The probe PEB-DMA of Example 1 was dissolved in tetrahydrofuran to obtain a concentration of 1×10 -3 mol / L mother solution; dilute 2mL of the mother solution to 200mL with tetrahydrofuran to obtain 1×10 -5 mol / L probe solution.

[0136] Take 2mL of the solution with a concentration of 1×10 -5 mol / L probe solution was used to test the fluorescence emission spectrum, and the fluorescence intensity was 717. Then, 3 μL of 0.01 mol / L copper chlorate solution was added to it, and the fluorescence emission spectrum was measured, and the fluorescence intensity was 952, which was a 33% increase in fluorescence. Finally, different nitrate interfering ions were added to the system: Cd 2+ 、Ni 2+ , Cu 2+ , Ca 2+ 、Co 2+ , Pb 2+ , K + Cr 3+ , Fe 2+ 、Al 3+ , Mn 2+ 、Zn 2+ , and measure the change of fluorescence intensity (E X =420nm, Slit:8*8, Scan:500). The anti-interference test results of the probe PEB-DMA of Example 1 on metal ions are as follows: Fig.12 As shown, Fig.12 It can be seen that although Ni 2+ , Ca 2+ Metal ions have a certain influence on the recognition effect of probe PEB-DM, but the fluorescence intensity of probe PEB-DM is still increased, indicating that probe PEB-DM has a certain anti-interference ability.

[0137] (7) Fluorescence titration test of the probe on cupric chlorate (E X =420nm,Slit:8*8,Scan:500)

[0138] The probe N-BPA of Example 1 was dissolved in tetrahydrofuran to obtain mother solutions of different concentrations. The fluorescence titration spectra of the probe of Example 1 to different concentrations of copper chlorate are shown in FIG. Fig.13 As shown, the titration fitting curve and titration linear regression diagram of the probe to copper chlorate are shown in Fig.14 As shown in a and b, the color change of the probe before and after the reaction with copper chlorate is as follows Fig.15 As shown. Fig.13 It can be seen that as the concentration of copper chlorate increases, the fluorescence intensity at 510 nm increases. When the concentration of copper chlorate increases to 6.0×10 -6 mol / L, the fluorescence intensity increased to above 950, Fig.15 It can be seen that under 365nm ultraviolet light, the solution can be observed to change from bright light to brighter light. -6 ~4.5×10 -6 mol / L concentration range, the titration fluorescence emission spectrum data was substituted into the Benesi-Hildebrand equation for calculation: I0 / I=1+K SV* [Cu(ClO3)2], according to Fig.14 It can be seen that the curve shows a good linear relationship, and the linear equation is y = 1.12-0.10×10 6 *x, linear correlation coefficient: R 2 =0.986, and the fitting constant of probe PEB-DMA was 1.0×10 5 L / mol, according to the detection limit calculation formula LOD = 3σ / K sv [σ=2.16(standard deviation of blank sample fluorescence response value)], the detection limit of probe PEB-DMA was calculated to be 6.4×10 -5 mol / L. The experimental results show that the fluorescent probe PEB-DMA has high detection sensitivity for low concentration of copper chlorate and low detection limit. Therefore, the fluorescent probe PEB-DMA can be used as a potential fluorescent probe to detect copper chlorate in the environment.

[0139] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A benzothiazole fluorescent probe for detecting cupric chlorate, characterized in that: The structural formula of benzothiazole fluorescent probe is: The benzothiazole fluorescent probe is (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline.

2. The method for preparing the benzothiazole fluorescent probe for detecting cupric chlorate according to claim 1, characterized in that: The following steps are included: 1) Concentrated sulfuric acid and concentrated nitric acid are mixed to obtain a mixed acid, 2-methylbenzothiazole is added dropwise to the mixed acid, and after the addition is completed, the reaction system continues to react to obtain 6-nitro-2-methylbenzothiazole; 2) reacting 6-nitro-2-methylbenzothiazole, methanol, Raney nickel and hydrazine hydrate under a nitrogen atmosphere to obtain 6-amino-2-methylbenzothiazole; 3) mixing 6-amino-2-methylbenzothiazole and hydrochloric acid to obtain a clear solution, sequentially adding a sodium nitrite aqueous solution and a potassium iodide aqueous solution dropwise to the clear solution, and continuing the reaction after the addition is complete to obtain 6-iodo-2-methylbenzothiazole; 4) mixing N,N-dimethylaniline, sodium bicarbonate aqueous solution and iodine and reacting them to obtain 4-iodo-N,N-dimethylaniline; 5) mixing 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine, triphenylphosphine and trimethylsilylacetylene, and reacting the mixture under a nitrogen atmosphere to obtain N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline; 6) mixing N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline and an organic solvent to obtain a clear solution, and reacting the clear solution, sodium fluoride and potassium carbonate under a nitrogen atmosphere to obtain 4-ethynyl-N,N-dimethylaniline; 7) mixing 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine, 4-ethynyl-N,N-dimethylaniline and triethylamine and reacting them under a nitrogen atmosphere to obtain N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline; 8) Under a nitrogen atmosphere, N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide are reacted, and the reaction product is reacted with p-dimethylaminobenzaldehyde to obtain (E)-4-(2-(6-((4-(dimethylamino)phenyl)ethynyl)benzo[d]thiazol-2-yl)vinyl)-N,N-dimethylaniline.

3. The preparation method according to claim 2, characterized in that: Step 1) The mass concentration of the concentrated sulfuric acid is 97-99%, the mass concentration of the concentrated nitric acid is 65-70%, the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 40-50:20-25; the volume molar ratio of the concentrated sulfuric acid to 2-methylbenzothiazole is 40-50mL:125-145mmol; During the dropping process, the temperature of the mixed acid is -5 to 0°C, and the dropping time is 28 to 32 minutes; the temperature of the continued reaction is 22 to 28°C, and the continued reaction time is 1.5 to 2.5 hours.

4. The preparation method according to claim 2 or 3, characterized in that: Step 2) The molar volume ratio of 6-nitro-2-methylbenzothiazole and methanol is 19-22 nmol:45-55 mL; the volume ratio of methanol and hydrazine hydrate is 45-55:8-12; the mass concentration of hydrazine hydrate is 78-82%; and the reaction time is 4-5 h.

5. The preparation method according to claim 4, characterized in that: Step 3) The molar volume ratio of 6-amino-2-methylbenzothiazole and hydrochloric acid is 10-14 mmol: 22-28 mL; the concentration of hydrochloric acid is 5-7 mol / L, the concentration of sodium nitrite aqueous solution is 0.9-1.1 mol / L, and the concentration of potassium iodide aqueous solution is 0.85-1.0 mol / L; the molar ratio of sodium nitrite to potassium iodide is 14-16: 13-15; The mixing temperature is -5 to 0°C; during the process of dropwise adding the sodium nitrite aqueous solution and the potassium iodide aqueous solution, the temperature of the clarified solution is -5 to 0°C; the continued reaction includes a first reaction and a second reaction, the temperature of the first reaction is -5 to 0°C, the time of the first reaction is 0.3 to 0.8h, the temperature of the second reaction is 22 to 28°C, and the time of the second reaction is 1.5 to 2.5h.

6. The preparation method according to claim 2 or 5, characterized in that: Step 4) The molar volume ratio of the N,N-dimethylaniline, the sodium bicarbonate aqueous solution and the iodine is 18-19.5 mmol: 28-32 mL: 15.5-17.2 mmol; the concentration of the sodium bicarbonate aqueous solution is 0.9-0.97 mol / L; The mixing temperature is ≤10°C; the reaction temperature is 22-28°C, and the reaction time is 0.5-1h.

7. The preparation method according to claim 6, characterized in that: Step 5) The molar ratio of 4-iodo-N,N-dimethylaniline, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and trimethylsilyl acetylene is 11-13: 0.3-0.36: 0.65-0.8: 0.08-0.1: 28-32; the molar volume ratio of tetrakistriphenylphosphine palladium and triethylamine is 0.3-0.36 mmol: 45-55 mL; the reaction temperature is 22-28° C., and the reaction time is 11-13 h.

8. The preparation method according to claim 7, characterized in that: Step 6) The molar volume ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline and the organic solvent is 4-5.2mmol:37-43mL; the organic solvent is methanol and tetrahydrofuran, and the volume ratio of methanol to tetrahydrofuran is 0.8-1.2:0.8-1.2; the molar ratio of N,N-dimethyl-4-((trimethylsilyl)ethynyl)aniline, sodium fluoride and potassium carbonate is 4-5.2:1.05-1.25:1.05-1.25; The reaction temperature is 37-43° C., and the reaction time is 3.5-4.5 h.

9. The preparation method according to claim 7 or 8, characterized in that: Step 7) The molar ratio of 6-iodo-2-methylbenzothiazole, tetrakistriphenylphosphine palladium, cuprous iodide, triphenylphosphine and 4-ethynyl-N,N-dimethylaniline is 1.76-1.86: 0.013-0.023: 0.08-0.1: 0.08-0.1: 2.07-2.27; the molar volume ratio of tetrakistriphenylphosphine palladium and triethylamine is 0.013-0.023 mmol: 28-32 mL; The reaction temperature is 22-28° C., and the reaction time is 11-13 hours.

10. The preparation method according to claim 9, characterized in that: Step 8) The molar volume ratio of N,N-dimethyl-4-((2-methylbenzo[d]thiazol-6-yl)ethynyl)aniline, sodium amide and N,N-dimethylformamide is 0.63-0.73 mmol:0.9-1.1 mmol:28-32 mL; the molar ratio of sodium amide and p-dimethylaminobenzaldehyde is 0.9-1.1:0.9-1.1; The reaction time is 0.8 to 1.2 hours; the second reaction time is 46 to 50 hours.

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