Fluorescent probe as well as preparation method and application thereof

Abstract

The invention belongs to the field of detection, and particularly discloses a fluorescent probe as well as a preparation method and application thereof. The fluorescent probe comprises a compound as shown in a formula (I). The fluorescent probe shows relatively high brightness and stable fluorescence emission characteristics in a liquid state, has efficient sensitivity and selectivity to Hg < 2 + >, is not interfered by other metal ions, is relatively short in detection time, can realize detection within 30 minutes, can realize complete detection within about 30 seconds at the soonest, and is relatively high in sensitivity, high in sensitivity and high in selectivity to Hg < 2 + >. When being applied to a test strip, the fluorescent probe can realize visual detection, and can be applied to detection of Hg < 2 + > in environmental samples, such as actual water samples and soil samples. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the field of detection, and specifically relates to a fluorescent probe and a preparation method and application thereof. Background Art

[0002] Mercury is a highly toxic, non-degradable metal pollutant that is extremely harmful to biological and ecological systems. 2+ The main analytical methods include atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, electrochemical detection, etc. Compared with traditional detection methods, organic small molecule fluorescent probes have the advantages of structural diversity, good repeatability, easy modification, and clear sensing mechanism.

[0003] According to the relevant mechanism of action, common organic small molecules Hg 2+ Fluorescent probes are generally divided into two categories: (1) fluorescent probes based on simple coordination without obvious chemical bond breaking; (2) fluorescent probes based on chemical reactions with significant chemical bond breaking (such as C-S bond, C=S bond, etc.). 2+ Shows better selectivity and higher sensitivity.

[0004] More and more chemically reactive Hg 2+ Fluorescent probes have been designed, especially thioacetal Hg 2+ However, most of the thioacetal Hg 2+ Fluorescent probes tend to work in organic solvents because in solutions with high water content, the above probes are prone to π-π stacking in their aggregated state, resulting in severe fluorescence attenuation or even quenching, i.e., aggregation-induced fluorescence quenching (ACQ). Obviously, this ACQ phenomenon is very important for Hg in many actual samples. 2+ Monitoring is unfavorable and cannot accurately detect Hg in water samples 2+ content. Summary of the invention

[0005] In order to overcome at least one technical problem existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a fluorescent probe.

[0006] A second object of the present invention is to provide a method for preparing a fluorescent probe.

[0007] A third object of the present invention is to provide an application of the fluorescent probe in the field of detecting mercury ions.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a fluorescent probe, comprising a compound represented by formula (I),

[0010]

[0011] R1 is selected from

[0012] Each R2 is independently selected from C 1～5 of alkyl.

[0013] In some embodiments of the present invention, C 1～5 The alkyl group is selected from -CH3, -CH2CH3, -CH(CH3)2, -CH2CH2CH3, -CH2CH2CH2CH3, -CH2CH(CH3)2, -CH(CH3)CH2CH3, -C(CH3)3, -CH2CH2CH2C H2CH3, -CH2CH2CH(CH3)2, -CH2CH(CH3)CH2CH3, -CH(CH3)CH2CH2CH3, -C(CH3)2CH2CH3, -CH2C(CH3)3 or -CH(CH3)CH(CH3)2.

[0014] In some embodiments of the present invention, R1 is selected from

[0015] In some embodiments of the present invention, each R2 is independently selected from C 1～3 of alkyl.

[0016] In some embodiments of the present invention, the compound represented by formula (I) is selected from

[0017] In some embodiments of the present invention, the fluorescent probe further comprises a carrier.

[0018] In some embodiments of the present invention, the carrier comprises at least one of filter paper and porous material. In some embodiments of the present invention, the porous material is selected from at least one of sponge, activated carbon and molecular sieve.

[0019] In some embodiments of the present invention, the fluorescent probe further comprises a solvent.

[0020] In some embodiments of the invention, the solvent comprises water.

[0021] The second aspect of the present invention provides a method for preparing the fluorescent probe according to the first aspect of the present invention, comprising the following steps:

[0022] The product is prepared by reacting N-(4-benzaldehyde)carbazole with compound A or compound B;

[0023] The compound A is

[0024] Compound B is n is an integer selected from 2-5.

[0025] In some embodiments of the present invention, the reaction is carried out with the participation of elemental iodine.

[0026] In some embodiments of the present invention, the reaction is carried out in the presence of a solvent.

[0027] In some embodiments of the present invention, the reaction time is 1 to 24 hours.

[0028] The third aspect of the present invention provides the use of the fluorescent probe described in the first aspect of the present invention in the field of detecting mercury ions.

[0029] The beneficial effects of the present invention are: the fluorescent probe in the present invention exhibits high brightness and stable fluorescence emission characteristics in liquid state, and has a good effect on Hg 2+ It has high sensitivity and selectivity, is not interfered by other metal ions, and takes a short time to detect. It can be completed within 30 minutes, and the fastest can be completed in about 30 seconds. When it is applied to test strips, it can realize visual detection. It can be applied to environmental samples, such as actual water samples and soil samples, Hg 2+ Detection.

[0030] The preparation method of the fluorescent probe in the present invention has the advantages of simple synthesis, low environmental pollution, simple operation, wide source of raw materials and low cost. The method does not require the use of expensive catalysts, customized drugs and instruments, the reaction is easy to control, the yield can reach more than 70%, and the material structure is simple. 1 H NMR, 13 The results were verified by analytical methods such as C NMR, HRMS and X-ray single crystal diffraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the X-ray single crystal diffraction pattern of the fluorescent probe 4a in Example 1.

[0032] Figure 2 This is a test graph of the fluorescence emission intensity of the fluorescent probe 4a in Example 1 after adding different metal ions.

[0033] Figure 3 Add Hg to the aqueous solution of fluorescent probe 4a in Example 1 2+ Fluorescence images before and after.

[0034] Figure 4 This is a test graph of the fluorescence emission intensity of the fluorescent probe 4b in Example 2 after adding different metal ions.

[0035] Figure 5 Add Hg to the aqueous solution of fluorescent probe 4b in Example 2 2+ Fluorescence images before and after.

[0036] Figure 6 is the fluorescence probe 4a in Example 1 for Hg 2+ Response time test chart.

[0037] Figure 7 is the fluorescent probe 4b in Example 2 for Hg 2+ Response time test chart.

[0038] Figure 8 The test paper loaded with the fluorescent probe 4a in Example 1 is Hg 2+ Detection diagram.

[0039] Fig. 9 The fluorescence probe 4a in Example 1 is used to detect Hg in actual water samples. 2+ Detection result diagram.

[0040] Fig.10 The fluorescence probe 4a in Example 1 is used to detect Hg in soil samples. 2+ Detection result diagram. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0042] Example 1

[0043] This example provides a fluorescent probe, denoted as 4a, whose structural formula is as follows:

[0044]

[0045] The synthetic route of the fluorescent probe in this example is:

[0046]

[0047] The synthesis steps of the fluorescent probe in this example are:

[0048] Weigh 167.2 mg of carbazole 1 and 40.0 mg of sodium hydroxide, add to the reaction bottle, add 15 mL of anhydrous N, N-dimethylformamide, heat under stirring, then add 124.1 mg of 4-fluorobenzaldehyde 2, and stir the reaction mixture in an oil bath at 130 ° C for 6 hours. Stop the reaction, cool to room temperature, pour the mixture into distilled water and extract with ethyl acetate. The organic layer is dried over anhydrous magnesium sulfate and concentrated by vacuum evaporation. The crude product is purified by column chromatography using a mixture of petroleum and dichloromethane (volume ratio 3: 1) as an eluent to obtain a white solid crude product, which is recrystallized from anhydrous ethanol to obtain a pure intermediate 3.

[0049] Weigh 67.8mg of intermediate 3 and 5.0mg of iodine, add 20mL of anhydrous dichloromethane, then add 106.1mg of methyl thioglycolate, after stirring at room temperature for 4 hours, by continuously adding Na2S2O3 aqueous solution (concentration is 0.1mol / L, 15mL) and NaOH solution (mass percent is 10%, 15mL) to terminate the reaction. Then use CH2Cl2 to extract the resulting mixture, and the organic layer is separated and dried and concentrated in vacuo using anhydrous Na2SO4. Column chromatography purification (eluent: petroleum ether / ethyl acetate volume ratio=10 / 1) obtains yellow oil afterwards, and recrystallization in CH2Cl2 and normal hexane obtains light yellow crystal 4a, and the melting point test result is mp=76.3℃-76.6℃.

[0050] The structural formula and relevant characterization data of fluorescent probe 4a are shown below:

[0051]

[0052] 1 H NMR (600MHz, DMSO-d6), δ, ppm: 3.48-3.62 (dd, J1=15.0Hz, J2=15.0Hz, 4H, CH2-20, CH2-23), 3.63 (s, 6H, OCH3-22, 25), 5.46 (s, 1H, CH-19), 7.29-7.32 (m ,2H,ArH-4,9),7.47-7.40(m,4H,ArH-2,3,10,11),7.66(d,J=8.4Hz,2H,ArH -14,18),7.69(d,J=8.4Hz,2H,ArH-15,17),8.26(d,J=7.8Hz,2H,ArH-5,8);

[0053] 13C NMR(150MHz,DMSO-d6),δ,ppm:34.12(C-20,23),52.67(C-22,25),53.09(C-19),110.14(C-2,11),120.67(C-4,9),121.04(C-5,8),123 .25(C-14,18),126.78(C-6,7),127.21(C-3,10),129.79(C-15,17),137.08(C-16),138.60(C-13),140.42(C-1,12),170.39(C-21,24);

[0054] ESI-MS, m / z (%): calculated as C 25 H 24 NO4S2([M+H] + ):466.1141(100), detected 466.1133.

[0055] The X-ray single crystal diffraction pattern of the fluorescent probe 4a in this example is as follows Figure 1 The results of hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum, high-resolution mass spectrometry and single crystal X-ray diffraction all showed that the molecular structure of compound 4a was consistent with its expectations.

[0056] Example 2

[0057] This example provides a fluorescent probe, denoted as 4b, whose structural formula is as follows:

[0058]

[0059] The synthetic route of the fluorescent probe in this example is as follows:

[0060]

[0061] The synthesis steps of the fluorescent probe in this example are:

[0062] Weigh 167.2 mg of carbazole 1 and 40.0 mg of sodium hydroxide, add to the reaction bottle, add 15 mL of anhydrous N, N-dimethylformamide, heat under stirring, then add 124.1 mg of 4-fluorobenzaldehyde 2, and stir the reaction mixture in an oil bath at 130 ° C for 6 hours. Stop the reaction, cool to room temperature, pour the mixture into distilled water and extract with ethyl acetate. The organic layer is dried over anhydrous magnesium sulfate and concentrated by vacuum evaporation. The crude product is purified by column chromatography using a mixture of petroleum and dichloromethane (volume ratio 3: 1) as an eluent to obtain a white solid crude product, which is recrystallized from anhydrous ethanol to obtain a pure intermediate 3.

[0063] Weigh 54.2 mg of intermediate 3 and 8.0 mg of iodine, add 15 mL of anhydrous dichloromethane, then add 48.7 mg of 1,3-propanedithiol, and reflux the reaction mixture for 10 h. After cooling, the reaction was terminated by continuously adding Na2S2O3 aqueous solution (concentration of 0.1 mol / L, 15 mL) and NaOH solution (mass percentage of 10%, 15 mL). Then extract the resulting mixture with CH2Cl2, separate the organic layer, dry it with anhydrous Na2SO4 and concentrate it in vacuo. Then purify it by column chromatography (eluent: petroleum ether / ethyl acetate volume ratio = 15 / 1), spin dry to obtain an oily substance, and recrystallize it in CH2Cl2 and n-hexane to obtain white crystals 4b, and the melting point test result is mp = 207.7℃-208.8℃.

[0064] The structural formula and relevant characterization data of the fluorescent probe 4b in this example are as follows:

[0065]

[0066] 1 H NMR (600MHz, CDCl3), δ, ppm: 1.95-2.25 (m, 2H, CH2-21), 2.95-3.01 (m, 2H, SCH2-22), 3.13 (t, 2H, J=12.0Hz, SCH2-20), 5.30 (s, 1H, CH-19), 7.27-7.32 (m ,2H,ArH-4,9),7.38-7.46(m,4H,ArH-2,3,10,11),7.56(d,J=8.4Hz,2H,ArH -14,18),7.71(d,J=8.4Hz,2H,ArH-15,17),8.14(d,J=7.8Hz,2H,ArH-5,8);

[0067] 13 C NMR(150MHz,DMSO-d6),δ,ppm:25.23(C-21),31.52(C-20,22),49.89(C-19),110.20(C-2,11),120.68(C-4,9),121.03(C-5, 8),123.24(C-14,18),126.81(C-6,7),127.27(C-3,10),129.84(C-15,17),137.19(C-16),139.17(C-13),140.37(C-1,12);

[0068] ESI-MS, m / z (%): calculated as C 22 H 19 NS2([M+H] +):362.1032(100), detected 362.1029.

[0069] The results of hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum and high-resolution mass spectrometry all showed that the molecular structure of compound 4b was consistent with its expectations.

[0070] Performance Test:

[0071] (1) Liquid sensing performance

[0072] Fifteen groups of 10 μmol / L aqueous solutions of the fluorescent probe 4a were prepared, and 50 μmol / L of different metal ions (specifically Na + Mg + , Ca 2+ Cr 3+ 、Co 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ 、Cd 2+ , Pb 2+ , Fe 2+ , Fe 3+ 、Al 3+ , Hg 2+ , add one metal ion to each group) for standby; then use a fluorescence spectrometer to ex =296nm (slit width is set to 5nm), voltage is 500V, and the fluorescence emission spectra of 15 groups of solutions are tested respectively. The specific test results are as follows Figure 2 and Figure 3 As shown, Figure 3 (a) is the fluorescence image of the aqueous solution of the fluorescent probe 4a; Figure 3 (b) is the addition of Hg 2+ The fluorescence image of the aqueous solution of the fluorescent probe 4a after Figure 2 and Figure 3 It can be found that the aqueous solution of fluorescent probe 4a has strong fluorescence. 3+ 、Na + Mg 2+ , Ca 2+ 、Zn 2+ , Cu 2+ 、Co 2+ Cr 3+ 、Cd 2+ 、Ni 2+ , Pb 2+ , Fe 2+ and Fe 3+ When Hg 2+ions, the fluorescence intensity of the fluorescence emission peak at 435nm decreased significantly, and the absorption peak red-shifted to 455nm. This indicates that the fluorescence probe 4a is sensitive to Hg 2+ It has high selectivity and can be used as a 2+ Ion-specific "off" probe.

[0073] 15 groups of aqueous solutions of fluorescent probe 4b with a concentration of 10 μmol / L were prepared, and 50 μmol / L of different metal ions (specifically Na + Mg + , Ca 2+ Cr 3+ 、Co 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ 、Cd 2+ , Pb 2+ , Fe 2+ , Fe 3+ 、Al 3+ , Hg 2+ , add one metal ion to each group) for standby; then use a fluorescence spectrometer to ex =296nm (slit width is set to 5nm), voltage is 500V, and the fluorescence emission spectra of 15 groups of solutions are tested respectively. The specific test results are as follows Figure 4 and Figure 5 As shown, Figure 5 (a) is the fluorescence image of the aqueous solution of fluorescent probe 4b; Figure 5 (b) is the addition of Hg 2+ The fluorescence image of the aqueous solution of the fluorescent probe 4b after Figure 4 and Figure 5 It can be found that the aqueous solution of fluorescent probe 4b has strong fluorescence. 3+ 、Na + Mg 2+ , Ca 2+ 、Zn 2+ , Cu 2+ 、Co 2+ Cr 3+ 、Cd 2+ 、Ni 2+ , Pb 2+ , Fe 2+ and Fe 3+ When Hg 2+ ions, the fluorescence emission peak intensity at 430nm decreased significantly, and the absorption peak red-shifted to 435nm. This indicates that the fluorescence probe 4b is sensitive to Hg 2+It has high selectivity and can also be used as a 2+ Ion-specific "off" probe.

[0074] (2) Hg 2+ Response time

[0075] Prepare two sets of 10 μmol / L aqueous solutions of fluorescent probe 4a, add one set of solutions into a quartz cuvette, place it in a fluorescence spectrometer, and quickly add 50 μmol / L Hg 2+ The solution was then tested and the relationship between the maximum intensity and time was recorded. Another group was directly placed in a fluorescence spectrometer to test its fluorescence intensity. The test conditions were: ex =296nm (slit width is set to 5nm), voltage is 500V, and the fluorescence intensity is tested. The specific test results are as follows Figure 6 From Figure 6 It can be found that when Hg is quickly added to the solution of fluorescent probe 4a 2+ Solution, compound 4a and Hg 2+ The reaction was basically quenched within 30 seconds, and the maximum fluorescence intensity did not change significantly when the test time was extended. This shows that the fluorescent probe 4a is expected to be used as a Hg 2+ Real-time sensors.

[0076] Prepare two sets of 10 μmol / L aqueous solutions of fluorescent probe 4b, add one set of solutions into a quartz cuvette, place it in a fluorescence spectrometer, and quickly add 50 μmol / L Hg 2+ The solution was then tested and the relationship between the maximum intensity and time was recorded. Another group was directly placed in a fluorescence spectrometer to test its fluorescence intensity. The test conditions were: ex =296nm (slit width is set to 5nm), voltage is 500V, the fluorescence intensity is tested, the specific test results are as follows Figure 7 From Figure 7 It can be found that when Hg is added to the solution of fluorescent probe 4b 2+ After solution, compound 4b reacts with Hg 2+ The reaction was quenched completely within 25 min. This may be because the six-membered ring structure of compound 4b is more stable, and Hg 2+ The reaction requires the opening of the six-membered ring, which takes a long time.

[0077] (3) Test paper loaded with compound 4a for Hg 2+ Detection Application

[0078] Cut 4 blank filter paper strips of the same size for later use; prepare 10 mL of compound 4a (solvent: dichloromethane, concentration: 1×10 -3mol / L) solution; then soak the filter paper in the compound 4a solution for half an hour, take it out and dry it to complete the preparation of the portable test strip; prepare different concentrations (1×10 -3 mol / L to 1×10 -5 mol / L) of Hg 2+ Water solution, take 10μL of solution and drop it on the test paper. Let it stand for five minutes, wait for the test paper to dry, and observe the change of fluorescence intensity on the test paper under 365nm ultraviolet light. The specific test results are as follows Figure 8 As shown by Figure 8 It can be seen that different concentrations of Hg 2+ The quenching effect of the solution on the test paper was different, while the fluorescence of the blank control test paper remained unchanged. Therefore, the experimental results show that these test papers can be developed into portable, visual detection of Hg 2+ sensing tools.

[0079] (4) Effect of compound 4a on Hg in actual water samples 2+ Detection

[0080] Distilled water, tap water and river water were used as research objects. The Hg 2+ Conduct fluorescence emission spectrum test and fluorescence analysis to calculate Hg 2+ Different concentrations of Hg were added to different water samples. 2+ (0μmol / L, 0.1μmol / L, 0.5μmol / L, 1μmol / L), add the above water sample to 1mL of 10μmol / L aqueous solution of 4a, and then use fluorescence spectrometer to test its maximum fluorescence intensity. The specific test results are as follows Fig. 9 As shown. Fig. 9 It can be seen that the fluorescence intensity of compound 4a increases with the change of Hg 2+ The present invention conducted three parallel tests to determine the recovery rate and relative standard deviation (RSD) to characterize the detection effect of the fluorescent probe 4a. The specific test results are shown in Table 1 below.

[0081] Table 1 Determination of Hg in actual water samples by fluorescent probe 4a 2+

[0082]

[0083] As shown in Table 1, compound 4a has a strong 2+ (Concentration is 10 -6 mol / L) with a recovery range of 95.9-107.2% and an RSD of less than 3%. These results indicate that compound 4a is suitable for the detection of Hg in actual water samples. 2+ .

[0084] (5) Effect of compound 4a on Hg in soil samples 2+ Detection

[0085] Four 0.1 g laboratory soil samples were weighed and then immersed in 1 mL of Hg 2+ (Concentrations are 0μmol / L, 0.1μmol / L, 0.5μmol / L, 1μmol / L) solution, placed at room temperature for 5 hours. Then centrifugation and microporous membrane filtration were used to obtain the treated Hg with different concentrations. 2+ Add the above Hg to 1 mL of 4a with a concentration of 10 μmol / L 2+ The solution is then subjected to fluorescence emission spectrum test and fluorescence analysis calculation, wherein the fluorescence emission spectrum test result is as follows: Fig.10 The fluorescence analysis calculation results are shown in Table 2.

[0086] Table 2 Determination of Hg in soil samples by compound 4a 2+

[0087]

[0088] Depend on Fig.10 It can be seen that adding different concentrations of Hg 2+ The fluorescence intensity of compound 4a changes with the 2+ As shown in Table 2, compound 4a has an effect on Hg 2+ The recovery range is 96.9-107% with RSD less than 1.5%, which is suitable for detecting Hg in soil samples. 2+ It can be seen that compound 4a can be used for qualitative and quantitative detection of Hg in actual soil samples. 2+ , and the recovery rate is high.

[0089] In summary, the present invention constructs a method for detecting Hg by modifying the carbazole fluorophore with a thioacetal structure. 2+ The fluorescent probes 4a and 4b are sensitive to Hg 2+ It has high selectivity and sensitivity and has been successfully applied to Hg in actual water samples and soil samples. 2+ The fluorescent probes 4a and 4b of the present invention can be used to detect Hg 2+ The sensing material overcomes the ACQ effect and exhibits aggregation-induced emission (AIE) characteristics. When loaded into the test strip for Hg 2+ Rapid detection of Hg can be achieved by visual identification 2+ The concentration level.

[0090] In addition, the present invention can realize the synthesis of fluorescent probes 4a and 4b without using expensive catalysts, customized drugs and instruments, and the synthesis reaction is easy to control, the yield can reach 70%, and the material structure is simple. 1 H NMR, 13 The results were verified by analytical methods such as C NMR, HRMS and X-ray single crystal diffraction.

[0091] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A fluorescent probe, characterized in that: Including the compound represented by formula (I), R1 is selected from Each R2 is independently selected from C 1～5 of alkyl.

2. The fluorescent probe according to claim 1, characterized in that: R1 is selected from 3. The fluorescent probe according to claim 1, characterized in that: Each R2 is independently selected from C 1～3 of alkyl.

4. The fluorescent probe according to claim 1, characterized in that: The compound represented by formula (I) is selected from 5. The fluorescent probe according to any one of claims 1 to 4, characterized in that: The fluorescent probe also includes a carrier.

6. The fluorescent probe according to claim 5, characterized in that: The carrier includes at least one of filter paper and porous material.

7. The fluorescent probe according to any one of claims 1 to 4, characterized in that: The fluorescent probe also includes a solvent.

8. The fluorescent probe according to claim 7, characterized in that: The solvent includes water.

9. The method for preparing a fluorescent probe according to any one of claims 1 to 8, characterized in that: The following steps are involved: The product is prepared by reacting N-(4-benzaldehyde)carbazole with compound A or compound B; The compound A is Compound B is n is selected from integers of 2-5.

10. Use of the fluorescent probe according to any one of claims 1 to 8 in the field of detecting mercury ions.

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