Benzothiazole derivative fluorescent probe and application thereof in Pb < 2 + > detection

Abstract

The invention discloses a benzothiazole derivative fluorescent probe and application thereof in Pb < 2 + > detection, and belongs to the field of chemical analysis and detection. According to the present invention, the chromophore of the benzothiazole derivative is modified by the 2-pyridine formylhydrazine, such that the new compound can specifically recognize Pb < 2 + > in the aqueous solution and the electronic smoke compound, and the powerful tool is provided for the rapid detection of the Pb < 2 + > content in the electronic smoke compound.

Description

Technical Field

[0001] The present invention belongs to the field of chemical analysis and detection, and particularly relates to a benzothiazole derivative fluorescent probe and its application in the detection of Pb 2+ . Background Art

[0002] Lead ions (Pb 2+ ) are toxic substances that pose serious hazards to the human body and the environment. Long-term exposure to lead ions, even at low concentrations, may cause a series of health problems. Lead can enter the human body through the respiratory tract, digestive tract, and skin, and accumulate in organs such as bones, kidneys, and livers, especially having the most significant harm to the nervous system. The toxicity of lead is particularly serious for children, which can damage children's intellectual development, resulting in neurodevelopmental problems such as learning difficulties, inattention, and abnormal behavior. In adults, chronic lead poisoning can cause hypertension, kidney function damage, and nervous system diseases. In addition, lead ions may also have toxic effects on the reproductive system, immune system, and skeletal system. Therefore, it is quite valuable and meaningful to develop a highly sensitive and selective technology for the rapid detection of lead ions. So far, several methods for detecting lead ions have been developed, including colorimetry, electrochemistry, atomic absorption spectrometry, inductively coupled plasma mass spectrometry, etc. In contrast, fluorescence methods have been developed due to their high measurement efficiency, high sensitivity, excellent spatial and temporal resolution, etc., and are suitable for environmental monitoring and biological sample analysis. Many fluorescent lead ion sensors have been reported so far and applied in many aspects such as environmental monitoring and in vivo research, but these probes may encounter some problems, such as low quantum yield and small Stokes shift. Benzothiazole derivative dyes are selected as luminophores to improve the optical performance of the probe and solve the problems of low quantum yield and small Stokes shift due to their good photostability, large Stokes shift, high quantum yield, etc. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides a benzothiazole derivative fluorescent probe and its application in the detection of Pb 2+ . The benzothiazole derivative fluorescent probe of the present invention can specifically react with Pb 2+ and produce a "turn-off" type change in fluorescence signal. The content of Pb 2+ can be detected by detecting the change in fluorescence signal.

[0004] The benzothiazole derivative fluorescent probe of the present invention is a benzothiazole derivative modified with 2-pyridinecarboxylic hydrazide, with the molecular formula C 21 H 16 N 4 O 2 S, and its structure is shown as follows:

[0005] 。

[0006] The synthetic route of the benzothiazole derivative fluorescent probe of the present invention is as follows:

[0007] 。

[0008] Specifically, it includes the following steps:

[0009] Step 1: Dissolve 2-aminothiophenol (2.70 g, 20 mmol) and 5-methylsalicylaldehyde (2.48 g, 20 mmol) in 20 mL of anhydrous N,N-dimethylformamide, then add sodium metabisulfite (6 g, 31.6 mmol), and reflux at 110 °C for 3 h. Cool to room temperature, filter the precipitated solid and wash it with water, and dry it under vacuum to obtain Compound 1, which is a white solid (3.76 g, yield 78%).

[0010] Step 2: Weigh a mixture of Compound 1 (2.275 g, 9.43 mmol), HMTA (2.913 g, 20.74 mmol) and trifluoroacetic acid (30 mL), heat it to reflux and stir overnight. After cooling to room temperature, neutralize the acid with potassium hydroxide until a precipitate forms, filter and wash it with water, and dry it under vacuum to obtain Compound 2, which is a yellow solid (1.957 g, yield 77%).

[0011] Step 3: Weigh Compound 2 (1 g, 3.71 mmol) and 2-pyridinecarboxylic hydrazide (509.22 g, 3.71 mmol) and dissolve them in 30 mL of anhydrous ethanol. Heat the mixture to reflux and stir overnight, filter and wash the filter cake with ethanol, and dry it under vacuum to obtain Compound 3, which is a yellow-green solid (1.12 g, yield 77.65%).

[0012] The benzothiazole derivative fluorescent probe of the present invention is used in the preparation of Pb 2+ detection reagent.

[0013] The detection reagent can specifically recognize Pb in aqueous solution and electronic cigarette aerosol 2+ 。

[0014] The present invention provides a Pb 2+ fluorescent probe. By modifying the chromophore of the benzothiazole derivative with 2-pyridinecarboxylic hydrazide, the new compound can recognize Pb in aqueous solution and electronic cigarette aerosol 2+ 。It provides a powerful tool for the rapid detection of the content of Pb 2+ in electronic cigarette aerosol. Description of the Drawings

[0015] Figure 1The fluorescence changes of the probe (10 μM, left) and the probe + Pb 2+ (10 μM, right) under a 365 nm UV lamp.

[0016] Figure 2 The UV absorption spectra of the probe (10 μM) and the probe + Pb 2+ (10 μM).

[0017] Figure 3 This is the selectivity test of the probe. It can be seen from the figure that the reaction of the probe with Pb 2+ is not affected by potential interfering substances.

[0018] Figure 4 This is the interference test of the probe. It can be seen from the figure that in the presence of potential interfering substances, the reaction of the probe with Pb 2+ is not affected.

[0019] Figure 5 This is the fluorescence intensity at 585 nm after the reaction of the probe (10 μM) with Pb 2+ (0 - 8 μM) and the linear relationship diagram with the concentration of Pb 2+ It can be seen from the figure that the fluorescence intensity after the reaction of the probe with Pb 2+ (0 - 8 μM) has a good linear correlation with the concentration of Pb 2+ and the correlation coefficient R 2 = 0.9954. Detailed implementation mode

[0020] The technical solution of the present invention will be further analyzed and explained through specific embodiments below.

[0021] Example 1: Preparation of the target product

[0022]

[0023] Compound 2 (1 g, 3.71 mmol) and 2-pyridinecarboxylic hydrazide (509.22 g, 3.71 mmol) were weighed and dissolved in 30 mL of absolute ethanol. The mixture was stirred and refluxed overnight, filtered, and the filter cake was washed with ethanol and dried in vacuo to obtain Compound 3, a yellow-green solid (1.12 g, yield 77.65%). 1H NMR (600 MHz, DMSO-d6) δ 8.68 (dd, J = 4.2, 1.7 Hz, 1H), 8.54 (s, 1H), 8.12 (dd, J = 7.8, 1.6 Hz, 1H), 8.05 - 8.00 (m, 1H), 7.99 - 7.91 (m, 2H), 7.46 - 7.37 (m, 4H), 7.33 (d, J = 2.1 Hz, 1H).

[0024] Example 2: Fluorescence Detection

[0025] First, through testing a variety of mixed systems of organic solvents and water in different ratios, it was determined that the fluorescence change of Compound 3 before and after reacting with lead ions was the most significant in a mixed solvent of acetonitrile:ethanol:water = 2:2:1 (v:v:v). Figure 1 The organic solvents used in this system itself would not cause fluorescence quenching of Compound 3. Subsequently, through ultraviolet absorption spectroscopy testing, it was obtained that the maximum absorption wavelengths of Compound 3 in a mixed solvent of acetonitrile:ethanol:water = 2:2:1 (v:v:v) appeared at 290 nm and 360 nm. When we added Pb 2+ (10 μM) to the probe solution, the absorbances at 290 and 350 nm decreased, and at the same time, a new absorption band appeared at a longer wavelength (440 nm) (Figure). When observed with the naked eye, the color of the solution changed from colorless to light yellow.

[0026] We found that after the addition of Pb 2+ , the reaction between the probe and Pb 2+ was almost immediately completed, accompanied by a change in fluorescence intensity and solution color. We tested the probe with a variety of common interfering ions and determined that the probe had significant high selectivity and anti-interference ability for lead ions ( Figure 3 , Figure 4 ). Subsequently, we recorded the fluorescence intensity (Ex: 365 nm, Em = 585 nm) after the reaction of the probe (10 μM) with 0 - 10 μM Pb 2+ and found that the fluorescence intensity of the probe (10 μM) at 585 nm after the addition of lead ions was within the concentration range of 0 - 8 μM linearly related to Pb 2+A linear relationship was presented for the concentration. When the concentration exceeded 8 μM, the fluorescence intensity of the probe no longer decreased significantly. Then, a standard curve for the lead ion concentration in the range of 0 - 8 μM was plotted ( Figure 5 ), from which the detection limit of the probe was calculated to be as low as 0.841 μM. Through multiple calibrations and validations, the high precision and high reliability of the measurement results were ensured.

[0027] To evaluate the accuracy of the method, we conducted a standard addition recovery experiment. The Pb 2+ standard solution was added to the samples to make the final concentrations reach 0, 2, 4, 6, and 8 μM. The samples were analyzed by the optimized fluorescence quantification method, and the corresponding lead ion concentrations were calculated using the linear fitting equation. The results are shown in Table 1. The recoveries were in the range of 95.0% to 101.1%, confirming that the method had good accuracy for lead ions in the concentration range of 0 - 8 μM.

[0028]

Claims

1. A benzothiazole derivative fluorescent probe, characterized in that Its structure is as follows: 。 2. The method for preparing the benzothiazole derivative fluorescent probe according to claim 1, characterized in that The steps include: Step 1: Dissolve 2-aminobenzenethiol and 5-methylsalicylaldehyde in anhydrous N,N-dimethylformamide, then add sodium metabisulfite, reflux at 110°C for 3 h, cool to room temperature, filter the precipitated solid, wash with water, and vacuum dry to obtain compound 1 as a white solid; Step 2: Compound 1, HMTA and trifluoroacetic acid were weighed, the mixture was heated to reflux and stirred for reaction for 8-12 hours, after cooling to room temperature, the acid was neutralized with potassium hydroxide until a precipitate was precipitated, filtered and washed with water, and vacuum dried to obtain compound 2 as a yellow solid; Step 3: Weigh compound 2 and 2-pyridinecarboxylic acid hydrazide and dissolve them in anhydrous ethanol. Heat the mixture to reflux and stir to react for 8-12 hours. Filter and wash the filter cake with ethanol. Dry under vacuum to obtain compound 3, which is the target product. The synthetic route is as follows: 。 3. The benzothiazole derivative fluorescent probe according to claim 1 is used to prepare Pb 2+ Application in detection reagents.

4. The use according to claim 3, characterized in that: The detection reagent can specifically identify Pb in aqueous solution and / or electronic cigarette aerosol 2+ .

5. The use according to claim 4, characterized in that: The fluorescence intensity of the detection reagent at 585 nm is similar to that of Pb 2+ The concentration is linear.

6. The use according to claim 5, characterized in that: Pb 2+ The concentration is 0-8μM.

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