Preparation method of dicoumarin-based fluorescent probe and application of dicoumarin-based fluorescent probe in palladium detection

Abstract

The invention relates to the technical field of heavy metal detection, in particular to a preparation method of a dicoumarin-based fluorescent probe and application of the dicoumarin-based fluorescent probe in palladium detection, the fluorescent probe is synthesized by taking F, Cl and Br substituted dicoumarin as a fluorophore and allyl formate as a recognition group, and when palladium is added into the probe, obvious fluorescence appears, and the fluorescence is detected. The detection limit can reach 55nmol / L at the lowest, and the method has high selectivity in vivo and in vitro, realizes the purpose of rapid and efficient detection of palladium, and effectively solves the problems of expensive detection instruments, tedious operation, high personnel requirements and the like in palladium detection by using the technical scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal detection, and specifically relates to a preparation method of a fluorescent probe based on coumarin and its application in the detection of palladium. Background Art

[0002] Heavy metals play extremely important roles in fields such as industry and new energy. Among them, palladium (Pd 0 ) has been widely used in industries such as catalysts, jewelry, and fuel cells due to its special physical and chemical properties. However, it is easy to cause palladium residues, which can harm the environment and human health, leading to skin allergies, respiratory diseases, and other related diseases. Due to its significant impact on the environment and health, the detection of Pd 0 in industrial, environmental, and biological samples has attracted considerable attention.

[0003] Currently, traditional detection methods for Pd 0 include techniques such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). Although they can detect accurately, due to the complex sample processing required, the high detection cost, and the limitation of the need for professional detection operators, they are difficult to promote. In recent years, the literature has reported a variety of fluorescent probes applied to the detection of Pd 0 According to their different response mechanisms, they can be roughly divided into two categories: coordination-type fluorescent probes and reaction-type fluorescent probes. Coordination-type probes are based on the coordination of Pd with N, P, O receptor molecules. Such probes usually show rapid fluorescence responses, low detection limits, etc., but have the disadvantage of low selectivity; reaction-type probes are based on the chemical reaction of Pd 0 with corresponding recognition sites under different reaction conditions. Such probes have high selectivity and sensitivity, but the response time is usually slower than that of coordination-type probes.

[0004] Currently, there are few Pd 0 fluorescent probes that can be used for simultaneous in vivo and in vitro studies. Aiming at the problems of low selectivity, poor sensitivity, and expensive raw materials in the synthesis process of Pd 0 the field urgently needs to develop a Pd 0 fluorescent probe with simple operation, high sensitivity, fast recognition speed, and low detection limit.

[0005] In view of the above situation, in order to overcome the above technical problems, the present invention designed and synthesized a coumarin-based fluorescent probe and successfully applied it in the detection of Pd 0 to solve the above technical problems. Summary of the Invention

[0006] The technical objective to be achieved by the present invention is: Based on the recognition mechanism of Tsuji-Trost in reaction-type fluorescent probes, using allyl formate as Pd0 recognition site, using Pd 0 to carry out a nucleophilic substitution reaction with an allyl substrate, using coumarin as a fluorescent group, to obtain a Pd 0 fluorescent probe with high sensitivity, low detection limit and high selectivity, and conduct in vitro and in vivo application research.

[0007] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0008] A coumarin-based fluorescent probe, the chemical structure of the fluorescent probe is as follows:

[0009]

[0010] The substituent at the R position in the internal structure of the fluorescent probe is F, Cl, Br, and the chemical formula of the fluorescent probe is C 20 H 11 RO7.

[0011] A preparation method of a coumarin-based fluorescent probe, which is used to prepare a coumarin-based fluorescent probe; the synthesis route of the fluorescent probe is as follows:

[0012]

[0013] The steps of the preparation method are as follows:

[0014] Step 1: Determine the substituent at the R position in the internal structure of the fluorescent probe, R = F or Cl or Br; dissolve 4-fluoro-2-hydroxybenzaldehyde and diethyl malonate in absolute ethanol, add piperidine and acetic acid, heat to reflux, after the reaction is completed, cool the reaction solution to room temperature, pour it into ice water, and filter under reduced pressure to obtain compound 1;

[0015] Step 2: React compound 1 with resorcinol and 4-dimethylaminopyridine under a nitrogen atmosphere, heat and stir, after the reaction is completed, add 30 ml of absolute ethanol and ultrasonicate, and filter under reduced pressure to obtain compound 2;

[0016] Step 3: First dissolve compound 2 and triethylamine in THF, stir in an ice bath for 30 min, warm back to room temperature and add allyl chloroformate and stir, after the reaction is completed, rotary evaporate to remove the excess solvent, and separate and purify to obtain compound 3.

[0017] Preferably, when R = F, the synthesis route is as follows:

[0018]

[0019] In the above step 1, the molar ratio of 4-fluoro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; the reaction time is 7 to 12 h;

[0020] In the second step, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; the reaction time is 3 to 6 h;

[0021] In the third step, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran or dichloromethane.

[0022] Preferably, when R = Cl, the synthesis route is as follows:

[0023]

[0024] In the first step, the molar ratio of 4-chloro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; the reaction time is 7 to 12 h;

[0025] In the second step, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; the reaction time is 3 to 6 h;

[0026] In the third step, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran or dichloromethane.

[0027] Preferably, when R = Br, the synthesis route is as follows:

[0028]

[0029] In the first step, in step a, the molar ratio of 4-chloro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; the reaction time is 7 to 12 h.

[0030] In the second step, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; the reaction time is 3 to 6 h.

[0031] In the third step, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran or dichloromethane.

[0032] The fluorescent probe based on coumarin is applied to the detection of palladium.

[0033] The maximum excitation wavelengths of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in the present invention are 440 nm and 441 nm, 441 nm respectively, and the maximum emission wavelengths are 548 nm, 551 nm, 551 nm respectively, and Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd have excellent selectivity for Pd 0 with detection limits (LOD) of 55, 71, and 107 nmol / L.

[0034] The beneficial effects of the present invention are as follows:

[0035] (1) The three probes prepared by the present invention exhibit excellent selectivity in detecting Pd 0 and can accurately identify the target substance, avoiding the interference of other substances. This high selectivity enables the probe to work reliably even in complex environments and is particularly suitable for diverse detection scenarios such as water samples, cells, and zebrafish.

[0036] (2) The probes of the present invention are characterized by high sensitivity and rapid response, capable of quickly capturing trace amounts of palladium elements, significantly improving the detection efficiency. This rapid response not only saves time but also makes real-time monitoring possible, providing great convenience for scientific research and practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Now the above and other aspects of the present invention will be described by way of example only with reference to the drawings, wherein:

[0039] Figure 1 is the flow chart of the preparation method of the present invention;

[0040] Figure 2 (A) is the UV-Vis absorption spectra of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1;

[0041] Figure 2 (B) is the fluorescence spectra of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1;

[0042] Figure 2 (C) is the fluorescence spectra of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1 at pH 3 - 11;

[0043] Figure 2 (D) is the detection limits of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1;

[0044] Figure 2(F) is the selectivity test of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1;

[0045] Figure 2 (E) are the kinetic curves of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd prepared in Example 1;

[0046] Figure 3 is the detection of Pd in water samples by the probe Dcou-F-Pd prepared in Example 1 0 of;

[0047] Figure 4 is the imaging of Pd in living cells by the probe Dcou-F-Pd prepared in Example 1 0 imaging;

[0048] Figure 5 is the long-term imaging of Pd in living cells by the probe Dcou-F-Pd prepared in Example 1 0 of;

[0049] Figure 6 is the imaging of Pd in zebrafish by the probe Dcou-F-Pd prepared in Example 1 0 imaging. Detailed implementation manners

[0050] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0051] As Figures 1-6 shown, Example 1:

[0052] Preparation of the probe Dcou-R-Pd, synthesis of the compound cou-R:

[0053] Into a 100 ml flask, dissolve 4-fluoro-2-hydroxybenzaldehyde (0.472 g, 2 mmol) or 4-chloro-2-hydroxybenzaldehyde (0.778 g, 5 mmol) or 4-bromo-2-hydroxybenzaldehyde (0.398 g, 2 mmol), diethyl malonate in anhydrous ethanol (30 ml), add a catalytic amount of piperidine and acetic acid, heat to reflux, and keep stirring for 8 h. After the reaction is completed, cool the reaction solution to room temperature and pour it into 50 ml of ice water. Filter under reduced pressure to obtain a filter cake, wash with water, and dry in vacuo.

[0054] Compound cou-F: Light yellow solid (0.331 g, 70%) 1H NMR (400 MHz, DMSO, ppm) δ 8.59 (s, 1H), 7.65 (d, 1H), 7.00 (d, 1H), 6.78 (s, 1H), 4.24 (q, 2H), 1.30 (t, 3H). 13C NMR (151 MHz, DMSO) δ 166.12, 164.49, 162.51, 155.65, 148.40, 132.53, 113.00, 112.83, 103.80, 103.73, 61.23, 13.99.

[0055] Compound cou-Cl: Light yellow solid (0.591 g, 76%) 1H NMR (400 MHz, CDCl3, ppm) δ 8.44 (s, 1H), 7.60 (d, 1H), 7.57 (d, 1H), 7.33 (s, 1H), 4.43 (q, 2H), 1.41 (t, 3H). 13C NMR (101 MHz, CDCl3, ppm) δ 162.91, 156.00, 155.44, 148.55, 139.28, 132.11, 125.70, 118.12, 117.40, 116.86, 61.82, 14.55.

[0056] Compound cou-Br: Light yellow solid (0.302 g, 76%) 1H NMR (400 MHz, CDCl3, ppm) δ 8.76 (s, 1H), 7.86 (d, 1H), 7.79 (d, 1H), 7.63 (s, 1H), 4.3 (q, 2H), 1.3 (t, 3H). 13C NMR (101 MHz, CDCl3, ppm) δ 163.10, 155.93, 155.26, 148.78, 132.01, 128.57, 128.09, 119.77, 118.41, 117.1, 61.86, 14.51.

[0057] Synthesis of compound Dcou-R-OH:

[0058] Put compound cou-F (0.200 g, 0.85 mmol) or cou-Cl (0.126 g, 0.5 mmol) or cou-Br (0.398 g, 2 mmol), resorcinol (0.384 mg, 2.4 mmol), 4-dimethylaminopyridine (48 mg, 0.4 mmol) into a 50 ml flask, protected by N2, heated to 140 °C and stirred for 3 h. After the reaction, add 30 ml of absolute ethanol and sonicate for 30 min. Filter under reduced pressure to obtain the filter cake, and dry it in vacuo to obtain an orange-yellow solid.

[0059] Compound Dcou-F-OH: Orange-yellow solid (0.138 g, 69%). 1H NMR (400 MHz, DMSO, ppm) δ 8.41 (d, 1H), 8.20 (d, 1H), 7.50 (s, 1H), 7.33 (d, 1H), 6.91 (d, 1H), 6.74 (s, 1H). 13C NMR (151 MHz, DMSO) δ 157.19, 155.47, 155.09, 151.65, 140.68, 131.97, 131.90, 130.90, 114.98, 112.60, 108.13, 106.51, 104.86, 104.68, 103.00, 101.16.

[0060] Compound Dcou-Cl-OH: Orange-yellow solid (0.092 g, 73%). 1H NMR (400 MHz, DMSO, ppm) δ 8.32 (d, 1H), 8.18 (d, 1H), 7.68 (s, 1H), 7.50 (d, 1H), 6.93 (d, 1H), 6.77 (s, 1H); 13C NMR (101 MHz, DMSO, ppm) δ 165.19, 157.70, 155.99, 155.56, 154.48, 152.38, 139.69, 131.67, 131.59, 125.59, 118.15, 115.13, 107.69, 103.65, 103.4.

[0061] Compound Dcou-Br-OH: Orange-yellow solid (0.302 g, 76%). 1H NMR (400 MHz, DMSO, ppm) δ 8.25 (d, 1H), 8.20 (d, 1H), 7.79 (s, 1H), 7.62 (d, 1H), 6.92 (d, 1H), 6.76 (s, 1H). 13C NMR (101 MHz, DMSO, ppm) δ 165.04, 157.42, 155.73, 155.25, 155.02, 152.19, 131.38, 131.27, 128.29, 128.17, 120.76, 115.12, 114.86, 107.36, 103.37, 103.19.

[0062] Synthesis of Compound Dcou-R-Pd

[0063] First, dissolve compound Dcou-F-OH (0.100 g, 0.3 mmol) or Dcou-Cl-OH (0.100 g, 0.32 mmol) or Dcou-Br-OH (0.200 g, 0.56 mmol) and triethylamine (375 mg, 3.75 mmol) in THF. After stirring for 30 min under an ice bath, add allyl chloroformate (900 mg, 7.5 mmol) at room temperature and react for 6 h. After the reaction is completed, rotary evaporate to remove the excess solvent. The crude product is separated by flash column chromatography (pure DCM) and dried in vacuo to obtain a white solid.

[0064] Compound Dcou-F-Pd: White solid (0.025 g, 25%). 1H NMR (400 MHz, DMSO, ppm) δ 8.53 (d, 1H), 8.46 (d, 1H), 7.60 (s, 1H), 7.58 (d, 1H), 7.47 (s, 1H), 7.40 (d, 1H), 6.04 (m, 1H), 5.47 (d, 1H), 5.36 (d, 1H), 4.79 (d, 2H). 13C NMR (101 MHz, DMSO) δ 155.69, 155.48, 155.43, 155.27, 154.78, 152.27, 152.16, 135.52, 131.99, 131.33, 129.71, 125.50, 119.76, 118.77, 118.03, 115.60, 113.85, 110.96, 107.15, 69.82.

[0065] Compound Dcou-Cl-Pd: White solid (0.032 g, 30%). 1H NMR (400 MHz, DMSO, ppm) δ 8.53 (d, 1H), 8.42 (d, 1H), 7.86 (s, 1H), 7.60 (d, 1H), 7.57 (s, 1H), 7.55 (d, 1H), 7.46 (m, 1H), 6.01 (d, 1H), 5.47, 5.33 (d, 1H), 4.80 (d, 2H). 13C NMR (101 MHz, DMSO, ppm) δ 155.68, 155.39, 155.29, 155.12, 154.98, 152.23, 151.53, 139.79, 131.97, 131.27, 131.10, 125.64, 119.77, 118.87, 118.00, 114.70, 113.63, 110.99, 107.07, 69.83.

[0066] Compound Dcou-Br-Pd: White solid (0.060 g, 30%). 1H NMR (400 MHz, DMSO, ppm) δ 8.46 (d, 1H), 8.34 (d, 1H), 7.91 (s, 1H), 7.68 (d, 1H), 7.61 (s, 1H), 7.46 (d, 1H), 6.01 (m, 1H), 5.46 (d, 1H), 5.34 (d, 1H), 4.80 (d, 2H); 13C NMR (101 MHz, DMSO, ppm) δ 155.67, 155.39, 155.09, 154.95, 152.23, 151.64, 131.97, 131.22, 131.08, 128.70, 128.50, 120.88, 119.77, 118.86, 114.97, 113.61, 110.99, 107.17, 69.83, 40.60, 40.39, 40.18, 39.97, 39.76, 39.55, 39.35.

[0067] Spectral tests of the fluorescent probe: Prepare stock solutions of the fluorescent probe compounds Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd with dimethyl sulfoxide (DMSO) as the solvent and a concentration of 2 mmol / L. The test system is PBS / DMSO, 1:1, V / V, pH = 7.4. Add 10 μL of the probe stock solution to 2 mL of the test system, and then add 60 μL of 2 mmol / L Pd 0 , and use a UV-visible spectrophotometer to measure the UV-visible absorption spectrum of the solution and a fluorescence spectrometer to measure the fluorescence spectrum.

[0068] Experimental results: In the UV spectral test, the UV absorption at 350 nm is that of the probe Dcou-F-Pd itself. When Pd 0 is added and the probe reacts with Pd 0 , the fluorophore Dcou-F-OH is exposed, and a new absorption peak can be seen at 440 nm; when Pd 0 is added to the probes Dcou-Cl-Pd and Dcou-Br-Pd, the same phenomenon occurs, and new absorption peaks appear at around 441 nm.

[0069] Implementation Figure 2 (B): According to the test conditions of Implementation Figure 2 (A), add Pd 0 dropwise to the test system and perform fluorescence spectral tests.

[0070] Experimental results: Through the fluorescence spectral titration experiment, it can be found that the fluorescence of the probe Dcou-F-Pd itself is very weak. When Pd 0After that, the fluorescence intensity at 548 nm gradually increased. When the concentration of Pd 0 increased to 40 μmol / L, the reaction system reached saturation and the fluorescence intensity no longer changed significantly. In the Dcou-Cl-Pd and Dcou-Br-Pd test systems, Pd 0 was also added drop by drop. It can be seen that the fluorescence intensity at 551 nm gradually increased. When the concentration of Pd 0 increased to 40 μmol / L, the reaction system reached saturation and the fluorescence intensity reached its peak

[0071] Implementation Figure 2 (C): Fluorescence spectrum test in the pH range of 3 - 11

[0072] Experimental results: When the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd were at pH values between 3 and 10, the fluorescence intensity did not change significantly, indicating that the probes could stably exist between pH values 3 and 10. When Pd 0 was added to different pH value systems, it was found that when the pH value was in the range of 6 - 11, the fluorescence intensity doubled, while between pH values 3 and 6, the fluorescence intensity did not change significantly.

[0073] Implementation Figure 2 (D): LOD values of fluorescence intensity and concentration of Pd 0 in the concentration range of 0 - 10 μmol / L

[0074] Experimental results: For the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd in the concentration range of 0 - 10 μmol / L, the fluorescence intensity was in good linear relationship with the concentration of Pd 0 . The fitting regression linear equations were y = 111666x + 2517.1, y = 8835.5x - 7459.7, and y = 5770.6x - 3930.5 respectively. The linear correlation coefficients were R 2 = 0.9857, 0.9862, and 0.9895 respectively. After calculation, the LOD was 55, 71, and 107 nmol / L

[0075] Implementation Figure 2 (E): Selectivity test of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd.

[0076] Experimental results: At 548 nm, the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd had no obvious fluorescence themselves. When 2 mmol / L of Pd 0After that, the fluorescence intensity increased significantly; while under the same system test conditions, when other analytes were added, the fluorescence hardly changed and could be ignored.

[0077] Implementation Figure 2 (F): Kinetic curves of the probes Dcou-F-Pd, Dcou-Cl-Pd, and Dcou-Br-Pd.

[0078] Results: The probe Dcou-F-Pd itself had no obvious fluorescence at 548 nm. When 20 μmol / L of Pd was added to the probe solution 0 After that, the fluorescence intensity increased rapidly within a short time and reached the maximum value within 400 s, and the fluorescence intensity of the system remained in an equilibrium state within 30 min; when 20 μmol / L of Pd was added to the probes Dcou-Cl-Pd and Dcou-Br-Pd 0 After that, the same experimental phenomenon occurred as above, the fluorescence intensity increased rapidly, and reached the peak value within about 400 s respectively, and tended to be stable within 30 min. The probe Dcou-F-Pd with the best fluorescence properties was selected for subsequent Pd 0 detection experimental research.

[0079] Implementation Two: Detection of Different Water Samples by the Probe Dcou-F-Pd

[0080] Results: The probe Dcou-F-Pd with the best fluorescence properties was selected for the ability test of detecting actual water samples. The experimental results showed that the recovery rate of Pd in pure water 0 was between 87% and 97%, the recovery rate of Pd in tap water 0 was between 86% and 92%, and the recovery rate of Pd in sewage 0 was between 86% and 107%, fully indicating that the detection of Pd in actual water samples 0 had good accuracy and feasibility and had the potential for practical application.

[0081] Implementation Three: Exploration of the Optimal Imaging Concentration of the Probe: Add 20 μmol / L of Pd to a confocal dish 0 Incubate for 1 h. After incubation, add 0, 1, 5, 10, 15, 20, and 25 μmol / L of the probe Dcou-F-Pd to it and incubate for 30 min. Test the fluorescence changes in each group of cells by a laser confocal microscope under the conditions of λex = 488 nm and λem = 490 - 623 nm.

[0082] Results: When the probe Dcou-F-Pd concentration was 0 μmol / L, there was no fluorescence in the cells. When the probe concentration increased to 1 μmol / L, fluorescence appeared in the cells, proving that the probe had high sensitivity. As the probe concentration increased, the fluorescence intensity in the cells also increased, indicating that the probe can be used well to detect Pd 0 Level fluctuations.

[0083] Implementation 4: Long-term test of probe imaging: Add 20 μmol / L Pd to the confocal dish 0 After incubation for 1 hour, 20 μmol / L of the probe Dcou-F-Pd was added after 1 hour. The samples were scanned continuously at λex=488nm, λem=490-623nm within 0-20min with a scanning interval of 2min / time, and the changes in the fluorescence intensity of the probe within 0-20min were observed.

[0084] Results: The effect of probe Dcou-F-Pd on Hela cells within 20 min 0 Reaction time and stability of fluorescent probe. 0 Dcou-F-Pd responded quickly, and the fluorescence intensity reached the highest at 10 minutes and remained stable. Under 20 minutes of continuous laser irradiation, the fluorescence was not quenched, proving that the fluorescent probe has good photostability and anti-photobleaching ability.

[0085] Example 5: Probe for zebrafish Pd 0 Imaging study: The zebrafish were divided into two groups. The first group was a blank group without any treatment; the second group was an experimental group, in which 50 μmol / L Pd 0 After incubation for 30 min, 10 μmol / L of the probe Dcou-F-Pd was added to each of the two groups. After incubation for 30 min, the cells were washed three times with culture medium, and zebrafish were imaged using a laser confocal microscope at λex=488 nm, λem=490-623 nm.

[0086] Results: No Pd in ​​the blank group 0 After adding the probe, no fluorescence was observed. 50 μmol / L Pd 0 After adding the probe, obvious fluorescence appeared in the zebrafish. The experiment proved that the probe Dcou-F-Pd can detect Pd in ​​living organisms. 0 Conduct real-time dynamic monitoring.

[0087] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the patent scope of this case.

Claims

1. A fluorescent probe based on dicoumarin, characterized in that: The chemical structure of the fluorescent probe is as follows: The substituent at R in the internal structure of the fluorescent probe is F, Cl, or Br, and the chemical formula of the fluorescent probe is C 20 H 11 RO7.

2. A method for preparing a fluorescent probe based on dicoumarol, the method being used to prepare a fluorescent probe based on dicoumarol as claimed in claim 1; characterized in that: The synthetic route of the fluorescent probe is as follows: The steps of the preparation method are as follows: Step 1: Determine the substituent at R in the internal structure of the fluorescent probe, R = F or Cl or Br; dissolve 4-fluoro-2-hydroxybenzaldehyde and diethyl malonate in anhydrous ethanol, add piperidine and acetic acid, heat to reflux, and after the reaction is completed, cool the reaction solution to room temperature, pour it into ice water, and filter under reduced pressure to obtain compound 1; Step 2: Compound 1, resorcinol and 4-dimethylaminopyridine were heated and stirred under a nitrogen atmosphere. After the reaction was completed, 30 ml of anhydrous ethanol was added for ultrasonication, and the compound 2 was obtained by vacuum filtration; Step 3: First, compound 2 and triethylamine were dissolved in THF, stirred in an ice bath for 30 min, and then allyl chloroformate was added and stirred after returning to room temperature. After the reaction was completed, excess solvent was removed by rotary evaporation, and compound 3 (Dcou-R-Pd) was obtained by separation and purification.

3. A method for preparing a fluorescent probe based on dicoumarol according to claim 2, characterized in that: When R=F, the synthetic route is as follows: In the step 1, the molar ratio of 4-fluoro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; the reaction time is 7 to 12 hours; In the step 2, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; the reaction time is 3 to 6 hours; In the step 3, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran and dichloromethane.

4. A method for preparing a fluorescent probe based on dicoumarol according to claim 2, characterized in that: When R=Cl, the synthesis route is as follows: In the step 1, the molar ratio of 4-chloro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; the reaction time is 7 to 12 hours; In the step 2, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; the reaction time is 3 to 6 hours; In the step 3, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran and dichloromethane.

5. The method for preparing a fluorescent probe based on dicoumarol according to claim 2, characterized in that: When R=Br, the synthesis route is as follows: In the step 1, in step a, the molar ratio of 4-chloro-2-hydroxybenzaldehyde to diethyl malonate is 1:1 to 1:1.2; and the reaction time is 7 to 12 hours. In the step 2, the molar ratio of compound 1 to resorcinol is 1:1 to 2:1; and the reaction time is 3 to 6 hours. In the step 3, the molar ratio of compound 2 to allyl chloroformate is 1:2 to 1:10, and the reaction solvent is tetrahydrofuran or dichloromethane.

6. Application of a fluorescent probe based on dicoumarin in the detection of palladium, A dicoumarin-based fluorescent probe according to claim 1, characterized in that: The dicoumarin-based fluorescent probe is used in detecting palladium.

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