A coumarin-based ratiometric fluorescent probe for detecting mercury ions, its preparation method and application

Abstract

The present invention discloses a coumarin-based ratiometric fluorescent probe for detecting mercury ions, its preparation method and application, belonging to the technical field of mercury ion detection. The present invention uses 2,4-dihydroxybenzaldehyde as a raw material, and undergoes a condensation cyclization reaction with 4-hydroxy-6-methylpyran-2-one to prepare 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione; 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione then undergoes an aldol condensation reaction with 4-diphenylaminobenzaldehyde to obtain a coumarin-based ratiometric fluorescent probe. Under the irradiation of a 365 nm ultraviolet lamp, the coumarin-based ratiometric fluorescent probe solution emits orange fluorescence. After adding Hg<supgt;2+< / supgt; to it, the fluorescence color of the solution changes from orange to blue, and the detection limit for Hg<supgt;2+< / supgt> reaches 2.24×10<supgt;‑7< / supgt> mol / L, having good application prospects as a fluorescent probe for detecting Hg<supgt;2+< / supgt> ions.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescence detection, and particularly relates to a coumarin-based ratio-type fluorescent probe for detecting mercury ions, a preparation method thereof, and an application thereof. Background Art

[0002] Coumarin is a natural product belonging to flavonoid plant secondary metabolites, with low toxicity and rich biological activities. In addition, coumarin also has good water solubility and a series of excellent optical properties, including good photostability, high fluorescence intensity and fluorescence quantum yield, and large Stokes shift. Therefore, it is of great significance to design and synthesize novel coumarin-based fluorescent compounds.

[0003] Mercury is an important metal in human production activities and has extensive applications in fields such as electroplating, metallurgy, thermometers, catalysis, and agriculture. However, mercury ions (Hg 2+ ) are highly toxic heavy metals that can easily penetrate biological membranes when combined with inorganic or organic ligands, accumulate in the human body through the skin, food chain, and respiratory tract, etc. After accumulating to a certain concentration, they cause irreversible nerve damage to the human body and trigger various diseases (brain damage, central nervous system defects, kidney damage, arrhythmia, etc.). In addition, Hg 2+ emissions from waste incineration, coal-fired power plants, etc. will cause environmental pollution. Therefore, it is very necessary to design and develop a sensitive method for detecting Hg 2+ in a biological environment. The fluorescence probe method has the advantages of simple operation, high sensitivity, and low detection limit. Therefore, it is of great significance to design and develop a novel fluorescence probe for detecting Hg 2+ . Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the technical problems to be solved by the present invention are to provide a coumarin-based ratio-type fluorescent probe for detecting mercury ions, which can meet the use requirements for detecting Hg 2+ . Another technical problem to be solved by the present invention is to provide a preparation method of the above-mentioned coumarin-based ratio-type fluorescent probe for detecting mercury ions. Another technical problem to be solved by the present invention is to provide an application of the above-mentioned coumarin-based ratio-type fluorescent probe for detecting mercury ions in detecting Hg 2+ .

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A coumarin-based ratio-type fluorescent probe for detecting mercury ions is 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione, and its structural formula is:

[0007]

[0008] The preparation method of the coumarin-based ratiometric fluorescent probe for detecting mercury ions includes the following steps:

[0009] 1) Using 2,4-dihydroxybenzaldehyde as a raw material, reacting with 4-hydroxy-6-methyl-2-pyrone to obtain 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione;

[0010] 2) 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione undergoes an aldol condensation reaction with 4-diphenylaminobenzaldehyde to obtain 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione.

[0011] In step 1), 2,4-dihydroxybenzaldehyde reacts with 4-hydroxy-6-methyl-2-pyrone to obtain 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione. The specific preparation method includes:

[0012] (1) Add 0.5 - 1 g of 2,4-dihydroxybenzaldehyde, 0.5 - 1 g of 4-hydroxy-6-methyl-2-pyrone and 15 - 30 mL of ethanol into a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and then add 0.1 - 0.5 g of benzyltriethylammonium chloride, and reflux for 6 - 10 h.

[0013] (2) After the reaction is completed, filter the reaction solution through a sintered glass funnel. The filter cake is washed with distilled water and ethanol to obtain 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione.

[0014] In step 2), 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione undergoes an aldol condensation reaction with 4-diphenylaminobenzaldehyde to obtain 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione. The specific preparation method includes:

[0015] (1) Add 1 - 1.5 g of 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione, 10 - 20 mL of ethyl acetate, and 0.1 - 0.5 g of B2O3 to a 50 mL single-necked flask equipped with a stirrer, thermometer, and reflux condenser. Stir at 50 - 60 °C for 30 - 40 min. Then dissolve 1 - 1.5 g of 4-diphenylaminobenzaldehyde in 10 - 20 mL of ethyl acetate, add it to the reaction, and then add 1 - 2 mL of tributyl borate. Continue stirring for 30 - 40 min. Finally, add 3 - 4 drops of n-butylamine dropwise to the reaction solution, raise the temperature to 70 - 80 °C, stir for 12 - 15 h, then cool to 50 - 60 °C, add 5 - 7 mL of hydrochloric acid solution (2 mol / L), and finally react for 30 - 40 min.

[0016] (2) After the reaction solution is cooled to room temperature, wash it three times with deionized water. The organic phase is dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione.

[0017] The prepared solution of 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione (deionized water / THF = 8 / 2, v / v) emits orange fluorescence under 365 nm ultraviolet light irradiation. After adding Hg 2+ , the fluorescence color of the solution changes from orange to blue. Therefore, 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione can be used as a fluorescent probe for detecting Hg 2+ .

[0018] This invention uses 2,4-dihydroxybenzaldehyde as a raw material to react with 4-hydroxy-6-methyl-2-pyranone to obtain 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione; 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione undergoes an aldol condensation reaction with 4-diphenylaminobenzaldehyde to obtain the fluorescent probe 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione. Experiments confirm that the solution of the prepared 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione fluorescent probe (deionized water / THF = 8 / 2, v / v) emits orange fluorescence under 365 nm ultraviolet light irradiation. After adding Hg 2+ , the fluorescence color of the solution changes from orange to blue. Therefore, 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione can be used as a fluorescent probe for detecting Hg 2+ .

[0019] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0020] Coumarin is a natural product with low toxicity and good biocompatibility, and is widely used in the fields of electroplating, metallurgy, thermometers, catalysis, agriculture, etc. The 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione fluorescent probe prepared from coumarin in the present invention can be used as a fluorescent probe for detecting Hg 2+ and has good practical value. Brief description of the drawings

[0021] Figure 1 is the fluorescence spectrum of the 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione solution (deionized water / THF = 8 / 2, v / v) reacting with Hg in the concentration range of 0 - 200 μM 2+ ;

[0022] Figure 2 is the fluorescence intensity result diagram of the 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione solution (deionized water / THF = 8 / 2, v / v) reacting with different metal ions. Detailed implementation manners

[0023] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the embodiments.

[0024] Example 1

[0025] The synthesis reaction formula of the 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione fluorescent probe is as follows:

[0026]

[0027] The specific steps are as follows:

[0028] 1) Preparation of 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione:

[0029] Into a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 0.69 g of 2,4-dihydroxybenzaldehyde, 0.63 g of 4-hydroxy-6-methyl-2-pyrone and 25 mL of ethanol were added, and then 0.23 g of benzyltriethylammonium chloride was added. The mixture was refluxed for 8 h. After the reaction was completed, the reaction solution was filtered through a sintered funnel. The filter cake was washed with distilled water and ethanol to obtain 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione with a yield of 82% and a purity of 98.5%. 1 1H NMR (600 MHz, DMSO-d6) δ: 11.16 (s, 1H), 8.70 (d, J = 34.8 Hz, 1H), 7.82 (d, J = 18.7 Hz, 1H), 4.10 (s, 1H), 6.93 - 6.64 (m, 3H), 2.20 (s, 3H). 13 13C NMR (150 MHz, DMSO-d6) δ: 203.83, 198.01, 191.88, 175.25, 165.06, 164.67, 159.89, 158.28, 157.84, 157.01, 148.99, 147.08, 133.49, 132.72, 118.39, 114.95, 114.73, 111.55, 111.33, 102.27, 102.18, 100.51, 56.98, 30.86, 27.05. HRMS (m / z) [M+Na] + : calculated for C 13 H 10 O5+Na + : 269.0420, found: 269.0426。

[0030] 2) Preparation of 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione:

[0031] Into a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 1.23 g of 1-(7-hydroxy-coumarin-3-yl)-1,3-butanedione, 15 mL of ethyl acetate and 0.17 g of B2O3 were added, and the mixture was stirred at 60 °C for 30 min. Then, 1.37 g of 4-diphenylaminobenzaldehyde was dissolved in 15 mL of ethyl acetate and added to the reaction, followed by the addition of 1.36 mL of tributyl borate, and the stirring was continued for 30 min. Finally, 3 drops of n-butylamine were added dropwise to the reaction solution, the temperature was raised to 80 °C, and after stirring for 14 h, the temperature was lowered to 60 °C, and 6 mL of hydrochloric acid solution (2 mol / L) was added, and the reaction was carried out for 30 min. After the reaction solution was cooled to room temperature, it was washed three times with deionized water, the organic phase was dried over anhydrous sodium sulfate and filtered, and the organic phase was filtered under reduced pressure to obtain 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione, with a yield of 33% and a purity of 98.5%. 1 H NMR(600MHz,DMSO-d6)δ:11.12(s,1H),8.77(s,1H),7.81(d,J=8.6Hz,1H),7.63(d,J=8.4Hz,2H),7.57(d,J=15.7Hz,1H),7.36(t,J=7.7Hz,4H),7.15(t,J=7.4Hz,2H),7.10(d,J=7.9Hz,4H),7.02(s,1H),6.89-6.82(m,4H),6.77(s,1H). 13 C NMR(150MHz,DMSO-d6)δ:183.10,181.34,164.78,158.68,157.28,149.88,147.61,146.70,140.91,132.93,130.52,130.27,127.98,125.83,124.89,121.73,121.06,116.51,114.79,111.69,102.23,101.27.HRMS(m / z)[M+H] + :calculatedfor C 32 H 23 NO5+H + :502.1649,found:502.1643.

[0032] Example 2

[0033] Take the 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione fluorescent probe prepared in Example 1 and disperse it in a solution (deionized water / THF = 8 / 2, v / v) to prepare a concentration of 1.0×10 -5The probe solution with a concentration of mol / L was measured by a fluorescence spectrophotometer (excitation wavelength: 365 nm, slit width: 10.0 nm / 4.0 nm) for the fluorescence emission spectra after adding different concentrations of Hg 2+ (0 - 200 μM), as shown in Figure 1 . The results showed that as the concentration of Hg 2+ gradually increased, the signal peak of 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione at 620 nm gradually decreased, while the signal peak at 447 nm gradually increased, indicating that 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione could sensitively detect the Hg 2+ concentration in the solution, and the detection limit for Hg 2+ was as low as 2.24×10 -7 mol / L.

[0034] Example 3

[0035] The 5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-penten-1,3-dione fluorescent probe prepared in Example 1 was dispersed in a solution (deionized water / THF = 8 / 2, v / v) to prepare a probe solution with a concentration of 1.0×10 -5 mol / L. Na + , K + , Mn 2+ , Ca 2+ , Zn 2+ , Ag + , Li + , Cd 2+ , Sn 2+ , Al 3+ , Cr 3+ , Mg 2+ , Ni + , La 3+ , Zr 2+ , Pb 2+ , Co 2+ , Cu 2+ , Fe 2+ , Fe 3+ (200 μM) were added, and the fluorescence emission spectra were measured by a fluorescence spectrophotometer (excitation wavelength: 365 nm, slit width: 10.0 nm / 4.0 nm). It can be seen from Figure 2 that when other metal ions were added, there was no obvious change in the fluorescence spectra; when Cu 2+ , Fe 2+ , Fe 3+When this occurs, fluorescence quenching takes place, and the signal peak at 620 nm disappears, but no new signal peak appears at 447 nm; only when Hg 2+ is added, the signal peak at 620 nm disappears and a new signal peak appears at 447 nm. This indicates that the probe has good selectivity for Hg 2+ and can perform specific detection of Hg 2+ .

Claims

1. A coumarin-based ratio fluorescent probe for detecting mercury ions, characterized in that, The structural formula is as follows: 。 2. The preparation method of the coumarin-based ratio fluorescent probe for detecting mercury ions according to claim 1, characterized in that, It includes the following steps: 1) Using 2,4-dihydroxybenzaldehyde as a raw material, reacting with 4-hydroxy-6-methyl-2H-pyran-2-one under the catalysis of benzyltriethylammonium chloride to generate 1-(7-hydroxycoumarin-3-yl)-1,3-butanedione; 2) 1-(7-hydroxycoumarin-3-yl)-1,3-butanedione undergoes an aldol condensation reaction with 4-diphenylaminobenzaldehyde under the catalysis of n-butylamine to prepare a coumarin-based ratiometric fluorescent probe for detecting mercury ions.

3. The preparation method of the coumarin-based ratio fluorescent probe for detecting mercury ions according to claim 2, characterized in that, The preparation process of step 1) is as follows: (1) In a 50 mL single-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, add 0.5 - 1 g of 2,4-dihydroxybenzaldehyde, 0.5 - 1 g of 4-hydroxy-6-methyl-2H-pyran-2-one and 15 - 30 mL of ethanol, and then add 0.1 - 0.5 g of benzyltriethylammonium chloride, and reflux for 6 - 10 h; (2) After the reaction is completed, filter the reaction solution through a sintered funnel, wash the filter cake with distilled water and ethanol, and dry to obtain 1-(7-hydroxycoumarin-3-yl)-1,3-butanedione.

4. The preparation method of the coumarin-based ratio fluorescent probe for detecting mercury ions according to claim 2, characterized in that, The preparation process of step 2) is as follows: (1) In a 50 mL single-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, add 1 - 1.5 g of 1-(7-hydroxycoumarin-3-yl)-1,3-butanedione, 10 - 20 mL of ethyl acetate and 0.1 - 0.5 g of B2O3, stir at 50 - 60 °C for 30 - 40 min; then dissolve 1 - 1.5 g of 4-diphenylaminobenzaldehyde in 10 - 20 mL of ethyl acetate and add it to the reaction, then add 1 - 2 mL of tributyl borate, and continue to stir for 30 - 40 min; finally, add 3 - 4 drops of n-butylamine to the reaction solution, heat up to 70 - 80 °C, stir for 12 - 15 h, then cool down to 50 - 60 °C, add 5 - 7 mL of hydrochloric acid solution, and finally react for 30 - 40 min; (2) After the reaction solution is cooled to room temperature, wash it three times with deionized water, dry and filter the organic phase with anhydrous sodium sulfate, and concentrate to obtain a preparation method of a coumarin-based ratiometric fluorescent probe for detecting mercury ions.

5. Use of the coumarin-based ratiometric fluorescent probe for detecting mercury ions as claimed in claim 1 in the detection of Hg 2+ ; the use is for non-disease-diagnostic purposes.

6. The application according to claim 4, wherein Under the irradiation of 365 nm ultraviolet light, the coumarin-based ratiometric fluorescent probe solution for detecting mercury ions emits orange fluorescence. After adding Hg 2+ to it, the fluorescence color of the solution changes from orange to blue.

7. The application according to claim 6, wherein The solvent of the coumarin-based ratiometric fluorescent probe solution for detecting mercury ions is deionized water / THF with a volume ratio of 8 / 2.

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