Water-soluble fluorescent probe, synthetic method thereof and application of water-soluble fluorescent probe in detection of SO2

Abstract

The invention relates to the field of organic fluorescent probes, in particular to a water-soluble fluorescent probe as well as a preparation method and application thereof in detection of SO2. The fluorescent probe is prepared by taking 4-bromotriphenylamine as a raw material, performing coupling and condensation, and finally performing salt forming reaction with 3-iodopropanol. The fluorescent probe has good water solubility, can realize transient response (less than 10 seconds), also has the advantages of high sensitivity, high selectivity, low detection limit (21.4 nM) and the like, and can be widely applied to real-time detection of SO2 content in different environments.

Description

Technical Field

[0001] The invention relates to the field of organic fluorescent probes, and in particular to a water-soluble fluorescent probe and a preparation method thereof and application thereof in detecting SO2. Background Art

[0002] SO2 is a common environmental pollutant that has many hazards to the environment and human health, such as forming acid rain and damaging the respiratory tract. In the food industry, sulfur dioxide is often used as a preservative and bleaching agent, but excessive use can have adverse effects on the human body, so it is of great significance to develop a method that can quickly and accurately detect sulfur dioxide.

[0003] Organic fluorescent probes use fluorescent substances as indicators and produce fluorescence under the excitation of light of a certain wavelength, and detect the generated fluorescence to achieve qualitative or quantitative analysis of the substance being detected. Water-soluble probes refer to probe molecules that can dissolve in water. Water-soluble probes are widely used in many fields due to their excellent solubility and functionality. For example, in environmental monitoring, water-soluble probes can be used to detect pollutants, heavy metal ions and harmful substances in water bodies. In addition, water-soluble probes are also used in chemical analysis, sensor technology, food safety testing and other fields. With their high sensitivity, selectivity and responsiveness, they have promoted the development of various scientific research and industrial applications.

[0004] The complexity of the design of water-soluble fluorescent probe molecules is mainly reflected in the balance between hydrophilicity and fluorescence performance, as well as the compatibility between functionality and water solubility. In order to improve water solubility, it is usually necessary to introduce hydrophilic groups into the molecules, but these modifications may destroy the conjugated system or charge transfer effect of the molecules, thereby reducing the fluorescence intensity or quantum yield, or even leading to fluorescence quenching. In addition, the probes must also have specific functions (such as targeting ability or environmental responsiveness), but the introduction of hydrophilic groups may interfere with the specific binding of the molecules to the target molecules, thereby affecting the functional performance of the probes. In order to achieve the combination of water solubility and functionality, the development of water-soluble probes usually requires multiple steps of chemical modification, but these steps often have low yields, high costs, and are extremely sensitive to reaction conditions. At the same time, the synthesis of water-soluble probes is often accompanied by the generation of a large number of by-products, especially molecules containing polar groups, whose separation and purification processes are complex and time-consuming, which also brings additional challenges to development and production. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a water-soluble organic fluorescent probe sensitive to SO2, which can be applied to the detection of SO2 in various types of water. The fluorescent probe has the characteristics of good water solubility, rapid response, high sensitivity, etc.

[0006] The first object of the present invention is to provide a water-soluble fluorescent probe, the chemical structural formula of which is: The second object of the present invention is to provide a method for synthesizing the water-soluble fluorescent probe, comprising the following steps: Step 1: Take 4-bromotriphenylamine and 4-methylphenylboronic acid, add dry tetrahydrofuran and toluene as solvents, and introduce N2; after reflux for 0.5 h, add a saturated solution of potassium carbonate distilled water as an inorganic alkaline catalyst, react for 0.5 h, add tetrakis(triphenylphosphine)palladium, and reflux for 12 h. After the reaction is completed, extract with ethyl acetate, dry and rotary evaporate to obtain a crude product, separate and purify by silica gel column chromatography to obtain a yellow solid.

[0007] The reaction equation is as follows: Step 2: Take 4'-(diphenylamine)-(1,1'-biphenyl)-4-carboxaldehyde and 4-pyridineacetonitrile, add methanol and piperidine, mix, reflux and stir at 80°C for 12 hours, separate and purify by silica gel column chromatography to obtain a bright red solid.

[0008] The reaction equation is as follows: Step 3: Take the above bright red solid and 3-iodopropanol, add acetonitrile, mix, reflux and stir at 90°C for 12h, spin dry, column chromatography, and recrystallize to obtain bright black needle-shaped crystals, which are the target product.

[0009] The reaction equation is as follows: Furthermore, the solvents required for column chromatography in step one are ethyl acetate and petroleum ether, wherein the volume ratio of ethyl acetate:petroleum ether is 1:4; the solvents required for column chromatography in steps two and three are methanol and dichloromethane, wherein the volume ratio of methanol to dichloromethane is 1:20.

[0010] Furthermore, in step 1, the molar ratio of the 4-bromotriphenylamine, 4-methylphenylboric acid and tetrakis(triphenylphosphine)palladium is 1:1.6:0.1, and the volume ratio of the dry tetrahydrofuran and toluene is 4:1.

[0011] Furthermore, in step 2, the molar ratio of the 4'-(diphenylamine)-(1,1'-biphenyl)-4-carboxaldehyde to 4-pyridineacetonitrile is 1:1.2, and the volume ratio of the methanol to piperidine is 20:1.

[0012] Furthermore, in step 3, the molar ratio of the solid to 3-iodopropanol is 1:3, and the amount of acetonitrile added is limited to 1 mmol of solid corresponding to 10 ml of acetonitrile.

[0013] The present invention also provides application of the water-soluble fluorescent probe in SO2 detection.

[0014] Furthermore, the response time of the assay was <10 s, and the detection limit was 21.4 nM.

[0015] Beneficial technical effects of the present invention: The present invention relates to a water-soluble fluorescent probe for rapid detection of SO2, which has the advantages of simple synthesis method and readily available raw materials, and the specifically modified triphenylamine derivative has the advantages of good water solubility, instantaneous response (<10 seconds), high selectivity, low detection limit (21.4 nM), etc. As an organic fluorescent probe, it can be widely used in the atmosphere, water resources and other environments for efficient detection of SO2.

[0016] The fluorescent probe compound has good water solubility, and the reasons include the following: ① The presence of hydrophilic groups: the molecule contains hydroxyl (-OH), which is very hydrophilic and can form hydrogen bonds or electrostatic interactions with water molecules, thereby significantly improving water solubility; ② The presence of polar bonds in the molecule, such as nitrile groups (C≡N), these polar groups can further enhance the solubility through dipole-dipole interactions with water molecules; ③ Ionization properties: the presence of quaternary ammonium salt parts enables the molecule to dissolve in water in the form of ions, and ionization helps to increase the solubility of the molecule. Since the probe molecule has good water solubility, no organic solvent is required during identification, thereby reducing toxicity and interference to the sample. Water-soluble fluorescent probes are suitable for chemical and environmental detection of various aqueous environments, broadening their application areas. In aqueous solutions, the probes can be evenly distributed to avoid aggregation effects due to poor solubility, thereby improving the sensitivity and accuracy of detection. The probes can also maintain high stability in aqueous solutions to avoid weakening of the fluorescence signal or inactivation of the probes due to precipitation or aggregation.

[0017] The fluorescent probe can achieve instantaneous response, conduct real-time dynamic monitoring, improve detection efficiency, and the probe with instantaneous response can adapt to the rapidly changing environment to accurately capture these transient processes and avoid information loss. Reduce the interference of other factors and improve the specificity of the signal. The probe with short response time can meet the demand for rapid detection, such as online monitoring of pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the target fluorescent probe molecule in Example 1; Figure 2 is the carbon NMR spectrum of the target fluorescent probe molecule in Example 1; Figure 3 The UV analysis spectrum of the target fluorescent probe molecule identifying SO2 in Example 2; Figure 4 The fluorescence analysis spectrum of the target fluorescent probe molecule recognizing SO2 in Example 2; Figure 5 This is a comparison chart of UV analysis of different ions of the target fluorescent probe molecule in Example 3; Figure 6 This is a comparison diagram of fluorescence analysis of different ions of the target fluorescent probe molecule in Example 3; Figure 7 Add HSO to the target fluorescent probe molecule in Example 4 3- / SO3 2- The peak intensity of fluorescence emission at 485 nm changes with time. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the embodiments.

[0020] Example 1 Preparation of water-soluble fluorescent probe The chemical formula of the water-soluble fluorescent probe is as follows: The specific reaction steps are as follows: Step 1: Take 4-bromotriphenylamine (5mmol) and 4-methylphenylboronic acid (8mmol), add dry tetrahydrofuran and toluene (THF / PhMe=20mL / 5mL) as solvent, protect with N2, reflux for 0.5h, add inorganic alkaline catalyst potassium carbonate (0.076mol) saturated solution of distilled water, continue to react for 0.5h, add tetrakis(triphenylphosphine)palladium (0.5mmol), reflux for 12h. After the reaction is completed, extract with ethyl acetate, dry, and rotary evaporate to obtain a crude product, which is separated and purified by column chromatography to obtain 1.03g of yellow solid with a yield of 59.2%.

[0021] The reaction equation is: Step 2: Take 4'-(diphenylamine)-(1,1'-biphenyl)-4-carboxaldehyde (0.6mmol) and 4-pyridineacetonitrile (0.72mmol), add 5.8ml methanol and 0.29ml piperidine, mix, reflux and stir at 80℃ for 12h, and silica gel column chromatography to obtain a bright red solid with a yield of 72.8%; The reaction equation is: Step 3: Take the above bright red solid (0.48 mmol) and 3-iodopropanol (1.44 mmol), add 4.8 ml of acetonitrile, mix, reflux and stir at 90°C for 12 hours, spin dry after the reaction, separate and purify by silica gel column chromatography, and recrystallize to obtain bright black needle-shaped crystals with a yield of 44.0%.

[0022] The reaction equation is: The H NMR spectrum of the target product is as follows Figure 1 As shown, the data is: 1 H NMR (400 MHz, DMSO-d6)δ(ppm): 9.14-9.13 (d, J = 4.0 Hz, Ar-H, 2H), 8.76 (s,-C=CH, 1H), 8.44-8.43 (d, J = 4.0 Hz, Ar-H,2H), 8.20-8.18 (d, J = 8.0Hz, Ar-H, 2H), 7.96-7.94 (d, J = 8.0 Hz, Ar-H, 2H), 7.77-7.75 (d, J = 8.0 Hz, Ar-H, 2H), 7.37-7.35 (t, J = 4.0 Hz, Ar-H,4H), 7.13-7.09 (m, Ar-H, 6H), 7.04-7.03 (d, J = 4.0 Hz, Ar-H, 2H), 4.72 (s, -OH, 1H), 4.69-4.67 (t, J =4.0 Hz, -CH2, 2H), 3.50-3.48 (t, J = 4.0 Hz, -CH2, 2H), 2.13-2.08 (m, -CH2, 2H). The carbon NMR spectrum of the target product is as follows Figure 2 As shown, the data is: 13C NMR (151 MHz, DMSO) δ (ppm): 151.60, 149.86, 148.54, 147.14,145.67, 144.49, 132.00, 131.84, 130.22, 128.50, 127.10,125.26, 124.34,123.74, 122.67, 116.95, 104.69, 58.63, 57.75, 33.70. Example 2 Targeted fluorescent probe for SO2 detection The concentration was 1×10 -5 mol·l -1 The target fluorescent probe aqueous solution is scanned by UV-visible spectrometer from 200nm to 600nm. The UV-visible spectrum is as follows Figure 3 As shown, there are two absorption peaks at 350nm and 475nm. - / SO3 2-After the solution, the absorption peak at 475nm disappears; its fluorescence spectrum is as follows Figure 4 As shown: In the blank probe solution, two strong absorption peaks appeared at 585 and 450 nm respectively. -5 mol / L HSO3 - / SO3 2- After the solution was obtained, there was only one strong absorption peak at 485 nm, and the fluorescence intensity was significantly enhanced.

[0023] Example 3 Selectivity of fluorescent probes Common ions may interfere with the detection of SO2, so it is necessary to determine whether the target fluorescent probe can have good selectivity in identifying SO2. The selected ions are: Na + Mg 2+ 、Zn 2+ NH4 + Cr 2+ , Pb 2+ , Cu 2+ , K + , Fe 3+ , Mn 2+ 、Al 3+ , Hg 2+ 、HCO3 2- 、CH3COO - , Cl - 、NO 2- 、CO3 2- , HS - 、SO4 2- , measure the UV spectrum, such as Figure 5 As shown in Figure 2, when interfering ions are added, the position of the maximum absorption peak does not change significantly. The excitation wavelength is selected and the fluorescence emission spectrum is measured to compare the response ability of the target fluorescent probe molecule to different ions. The results are shown in Figure 2. Figure 6 As shown, it can be seen that the addition of HSO3 - / SO3 2- The fluorescence of the ions was significantly enhanced, while the addition of other ions had no significant change.

[0024] Example 4 Response time of fluorescent probe At 1.0*10 -5 mol / L target probe molecule solution, different concentrations (5*10 -6 mol / L, 1*10 - 5 mol / L、2*10 -5 mol / L、5*10 -5 mol / L)HSO3 - / SO3 2- solution, select the excitation wavelength, and scan its fluorescence emission peak intensity at 660 nm, such as Figure 7 As shown, it can be seen that when adding different concentrations of HSO3 - / SO3 2 The emission peak intensity dropped sharply after the solution was dissolved, and a rapid response was made within 10 seconds. In addition, this fluorescent probe was used to detect HSO3 - / SO3 2- The minimum concentration of the fluorescent probe is 21.4 nM, which shows that the fluorescence probe is sensitive to HSO3 - / SO3 2- High sensitivity of detection.

Claims

1. A water-soluble fluorescent probe, characterized in that: Its chemical structure is: 。 2. A method for synthesizing a water-soluble fluorescent probe as claimed in claim 1, characterized in that: The steps include: Step 1: Take 4-bromotriphenylamine and 4-methylphenylboronic acid, add ultra-dry tetrahydrofuran and toluene as solvents, and introduce N2; after refluxing for 0.5 h, add a saturated solution of potassium carbonate distilled water as an inorganic alkaline catalyst, continue to react for 0.5 h, add tetrakis(triphenylphosphine)palladium, reflux for 12 h, and after the reaction is completed, extract with ethyl acetate, dry, and rotary evaporate to obtain a crude product, which is separated and purified by column chromatography to obtain a yellow solid; The reaction equation is as follows: Step 2: Take 4'-(diphenylamine)-(1,1'-biphenyl)-4-carboxaldehyde and 4-pyridineacetonitrile, add methanol and piperidine, mix, reflux and stir at 80°C for 12 hours, separate and purify by silica gel column chromatography to obtain a bright red solid; The reaction equation is as follows: Step 3: Take the above bright red solid and 3-iodopropanol, add acetonitrile, mix, reflux and stir at 90°C for 12h, perform rotary evaporation, column chromatography, and recrystallize to obtain bright black needle-shaped crystals, which are the target product; The reaction equation is as follows: 。 3. The method for synthesizing a water-soluble fluorescent probe according to claim 2, characterized in that: The solvents required for column chromatography in step 1 are ethyl acetate and petroleum ether, wherein the volume ratio of ethyl acetate:petroleum ether is 1:4; the solvents required for column chromatography in steps 2 and 3 are methanol and dichloromethane, wherein the volume ratio of methanol to dichloromethane is 1:

20.

4. The method for synthesizing a water-soluble fluorescent probe according to claim 2, wherein: In step 1, the molar ratio of the 4-bromotriphenylamine, 4-methylphenylboronic acid and tetrakis(triphenylphosphine)palladium is 1:1.6:0.1, and the volume ratio of the ultra-dry tetrahydrofuran and toluene is 4:

1.

5. The method for synthesizing a water-soluble fluorescent probe according to claim 2, wherein: In step 2, the molar ratio of the 4'-(diphenylamine)-(1,1'-biphenyl)-4-carboxaldehyde to 4-pyridineacetonitrile is 1:1.2, and the volume ratio of the methanol to piperidine is 20:

1.

6. The method for synthesizing a water-soluble fluorescent probe according to claim 2, characterized in that: In step 3, the molar ratio of the bright red solid to 3-iodopropanol is 1:3, and the amount of acetonitrile added is limited to 1 mmol of solid corresponding to 10 ml of acetonitrile.

7. Use of the water-soluble fluorescent probe as claimed in claim 1 in SO2 detection.

8. The use of the water-soluble fluorescent probe in SO2 detection according to claim 7, characterized in that: The response time was <10 seconds and the detection limit was 21.4 nM.

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