Fluorescent probe for detecting peroxy free radicals in atmosphere and preparation method of fluorescent probe

Abstract

The invention relates to the technical field of free radical detection methods, and particularly discloses a fluorescent probe for detecting peroxy free radicals in the atmosphere and a chemical structural formula of the fluorescent probe. The invention also provides a preparation method and application thereof. The fluorescent probe has good environmental friendliness, high sensitivity and selectivity, the preparation process is simple, materials are easy to obtain, and a new convenient means and thought are provided for detection of peroxy free radicals in the atmospheric environment.

Description

Technical Field

[0001] The invention belongs to the technical field of free radical detection methods, and specifically relates to a fluorescent probe for detecting peroxyl free radicals in the atmosphere and a preparation method thereof. Background Art

[0002] In recent years, with the use of electric vehicles and new energy sources in my country, problems such as automobile exhaust and industrial waste gas emissions have been effectively controlled, and regional air quality has been greatly improved. However, problems such as near-ground ozone and the explosive growth of secondary air pollutants still need to be solved. Atmospheric free radicals play an important role in this process. It is necessary to conduct in-depth research on their distribution and generation mechanism. Among atmospheric free radicals, peroxyl radicals (RO 2. , where R is any organic group) is the main source of secondary air pollutants in the atmospheric troposphere and is considered to be an important intermediate in the atmospheric free radical transformation cycle. 2. The types and transformation mechanisms of these compounds are crucial to protecting public health and breaking the cycle of atmospheric free radical pollution.

[0003] The existing atmospheric free radical detection technologies include electron spin resonance, chemical amplification, laser induced fluorescence, chemical ionization mass spectrometry and other methods. However, these detection methods often require expensive instruments and complex technologies, making it difficult to perform mobile measurements. At the same time, actual field detection has large interference, making it difficult to analyze the true free radical concentration signal.

[0004] Compared with the above technologies, the advantage of the chemical fluorescence probe method is that it has the potential to capture free radicals by species. Since the structure of the probe can only react specifically with one or a class of free radicals, it is not easily affected by other atmospheric oxidation species. The free radical adducts formed by the probe and the free radical can retain the R group structure information of the original peroxyl free radical, which provides a basis for further exploring the distribution of atmospheric peroxyl free radical species. At the same time, the chemical probe method also has the characteristics of simple operation and convenient collection, avoiding the complex assembly and handling process of the aforementioned various instruments. Therefore, the development of a fluorescent probe that can be used for the actual detection of atmospheric peroxyl free radicals and the corresponding sampling method is of great value and significance for the detection of atmospheric peroxyl free radicals. Summary of the invention

[0005] The first purpose of the present invention is to solve the problem of lack of detection method of peroxyl free radicals in the atmosphere and to provide a convenient and efficient fluorescent probe for detecting peroxyl free radicals in the atmosphere.

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

[0007] The third object of the present invention is to provide the application of the above fluorescent probe.

[0008] The purpose of the present invention is specifically achieved through the following technical solutions:

[0009] A fluorescent probe for detecting peroxyl radicals in the atmosphere, wherein the fluorescent probe has the following chemical structural formula:

[0010]

[0011] The method for preparing the fluorescent probe for detecting peroxyl radicals in the atmosphere comprises the following steps:

[0012] (1) 2,5-furandicarboxylic acid and thionyl chloride are mixed and stirred, DMF is added as a reaction catalyst, and a reflux reaction is carried out under an inert gas environment and heating conditions. After cooling to room temperature, the reactant is evaporated to remove excess thionyl chloride to obtain a solid compound 1;

[0013] (2) Compound 1 is dissolved in dichloromethane, and the yellow solution containing compound 1 is added dropwise to a dichloromethane solution containing the nitroxide free radical piperidinol, anhydrous sodium sulfate powder is added, and then pyridine is added as an acid binding agent, and the reaction is stirred under an inert gas environment, and then column chromatography is performed to obtain a solid product, which is a fluorescent probe.

[0014] Preferably, in step (1), the dosage ratio of the 2,5-furandicarboxylic acid to thionyl chloride is 0.5 mol:1 L; the volume ratio of the thionyl chloride to DMF is 100:1, and the reflux reaction is carried out at normal pressure and 70-80° C. for 3 h.

[0015] Preferably, in step (2), the molar ratio of the nitroxide free radical piperidinol to compound 1 is 1:1; the concentration of compound 1 after being dissolved in dichloromethane is 0.5 mol / L; the molar ratio of anhydrous sodium sulfate to compound 1 is 1:2, and the molar ratio of pyridine to compound 1 is 1:1; and the stirring reaction is carried out at room temperature for 12 hours.

[0016] Further preferably, in step (2), the column chromatography separation uses a mixed solvent of petroleum ether and ethyl acetate as an eluent, and the volume ratio of the petroleum ether to ethyl acetate is 4:1.

[0017] Preferably, the inert gas in step (1) and step (2) is nitrogen.

[0018] The above fluorescent probe is used to detect short carbon chain peroxyl radicals in the atmospheric environment.

[0019] Furthermore, the application of the fluorescent probe in the actual atmospheric environment is as follows: the fluorescent probe methanol solution is loaded on the surface of the glass fiber membrane, the prepared fluorescent probe membrane is placed on the atmospheric sampler, and air is passed through the fluorescent probe membrane in the external atmospheric environment. After the sampling is completed, the membrane components are dissolved in methanol and the fluorescence spectrum test is performed. The higher the fluorescence intensity, the higher the corresponding concentration of short carbon chain peroxyl radicals.

[0020] Preferably, the concentration of the fluorescent probe methanol solution is 10 mmol / L and the volume is 2 mL. During sampling, the flow rate of the air passing through the fluorescent probe membrane is 100 L / min. The diameter of the glass fiber is 90 mm.

[0021] The fluorescent probe prepared by the invention combines with peroxy radicals with different carbon chain lengths to generate free radical adducts with different molecular masses, and the concentration of peroxy radicals with corresponding carbon numbers can be obtained by gas chromatography-mass spectrometry analysis.

[0022] The probe capture reaction process of the present invention is as follows (taking methyl peroxyl radical as an example):

[0023]

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The fluorescent probe of the present invention has good environmental friendliness, high sensitivity and selectivity, and the preparation process is simple and the materials are readily available. The fluorescent probe can be used as a means for detecting the concentration of short-chain peroxyl free radicals in the atmospheric environment, filling the gap in the classification detection of peroxyl free radicals in the atmospheric environment, and providing a new and convenient means and idea for the detection of peroxyl free radicals in the atmospheric environment. The method of using the fluorescent probe to detect short-chain peroxyl free radicals in the atmospheric environment has high sensitivity, good repeatability and strong anti-interference ability, and can be applied to the concentration detection of short-chain peroxyl free radicals in actual complex atmospheric conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The fluorescence spectra of the probe film prepared by the fluorescent probe prepared in Example 1 under various weather conditions, the up and down order of the legend in the figure is the same as the up and down order of the intersection of the dotted line and the spectrum graph;

[0027] Figure 2 The fluorescence effect of various RO2 free radicals with different carbon chain lengths on the probe adduct induced in the laboratory simulation capture test process of the fluorescent probe prepared by the present invention;

[0028] Figure 3 The collected liquid after actual sampling of the fluorescent probe membrane prepared by the present invention is used for product analysis and detection by gas chromatography-mass spectrometry, and the EIC diagram (extracted ion chromatogram) of the probe and the free radical addition product;

[0029] Figure 4 is the positive ion spectrum of T-FDCA (fluorescent probe prepared by the present invention);

[0030] Figure 5 is the positive ion spectrum of T-FDCA (probe and C1RO2 adduct);

[0031] Figure 6 is the positive ion spectrum of T-FDCA (adduct of probe and C2RO2);

[0032] Figure 7 The distribution of short carbon chain (C1-C5) RO2 under different weather conditions. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0034] The raw materials in the examples of the present invention are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0035] Example 1

[0036] Synthesis of fluorescent probe (T-FDCA)

[0037] (1) Take 5 mmol 2,5-furandicarboxylic acid (FDCA) (0.78 g) and add it to 10 mL thionyl chloride, stir and mix, and add 0.1 mL N,N-dimethylformamide (DMF) as a catalyst. After all the raw materials are mixed, the container is evacuated, and then filled with nitrogen for protection, and stirred and refluxed in an oil bath at 75°C for 3 hours. The reaction obtains a light yellow clear liquid. After cooling to room temperature, the excess thionyl chloride is distilled off under reduced pressure to obtain a crystalline light yellow solid (compound 1,5-(chloroformyl)furan-2-carboxylic acid).

[0038] (2) The above compound 1 (5 mmol, 0.87 g) was dissolved in 10 mL of dichloromethane for later use, which was recorded as solution A. Meanwhile, 5 mmol of nitroxylpiperidinol (TEMPO) (0.86 g) was dissolved in 5 mL of dichloromethane. Solution A was added dropwise to the dichloromethane solution containing nitroxylpiperidinol. Then, 0.4 mL of pyridine (acid binding agent) and anhydrous sodium sulfate (2.5 mmol, 0.355 g, to remove a small amount of water that may be produced) were added. The mixture was stirred at room temperature for 12 h under nitrogen protection to obtain a crude fluorescent probe. Finally, the crude fluorescent probe was purified and separated by silica gel chromatography (ethyl acetate / petroleum ether 0:1-2:8). The obtained fluorescent probe (T-FDCA, 5-(nitroxylpiperidinol)methylfuranyl-2-carboxylic acid) was yellow crystals. MS (EI): 310.1291: [M+H]+: 311.1369.

[0039] The chemical structure of the T-FDCA fluorescent probe molecule is:

[0040]

[0041] 13 C NMR (101MHz, DMSO-d6) δ166.08,156.25,154.11,131.19,128.93,123.94,122.21,53.29,31.63,30.32.

[0042] 1 H NMR (400MHz, DMSO-d6) δ7.44(d,J=3.4Hz,1H),7.40(s,2H),4.35(q,J=7.0Hz,1H),1.33(t,J=7.1Hz,4H),1.16–1.03(m,12H).

[0043] Example 2

[0044] Study on atmospheric sampling of short-chain peroxyl radicals using fluorescent probe membrane

[0045] (1) The present invention uses a 10 mmol / L T-FDCA probe methanol solution as a capture agent, takes 2 mL of the above solution and loads it on the surface of a glass fiber membrane to make a fluorescent probe membrane, and after the solution is completely infiltrated, it is placed on a particulate matter atmospheric sampler, and atmospheric sampling is performed at an air flow rate of 100 L / min for 60 minutes, while recording the atmospheric condition parameters within the sampling time period.

[0046] (2) The probe membrane after collection was chopped up and dissolved in 10 mL of methanol. After ultrasonic-assisted dissolution for 5 min, the fluorescence emission spectrum test was performed (wavelength range 200-650 nm, excitation light wavelength 270 nm, emission slit width and receiving slit width were both 10 nm). The fluorescence spectra of the fluorescent probe membrane under various weather conditions are shown in Fig. Figure 1 , Figure 2 The fluorescence effects of various RO2 free radicals with different carbon chain lengths (AAPH: C1-C2; Isoprene: C5; Toluene: C6-C7) induced in the laboratory on the probe adduct.

[0047] (3) The collected liquid is subjected to product analysis and detection by gas chromatography-mass spectrometry, and its EIC diagram is as follows: Figure 3 As shown, the RO2 adduct products with different carbon numbers can be distinguished by the relative molecular mass of the products, among which the positive ion mass spectra of T-FDCA, T-FDCA-Me (C1 adduct), and T-FDCA-Et (C2 adduct) are shown as follows: Figure 4-6 shown.

[0048] The above-mentioned C1 adduct and C2 adduct are only probe radical adducts tested by mass spectrometry molecular ion peaks and fragment structures. They are short carbon chain RO2 radicals (C1: CH3O2.; C2: C2H5O2.; C3: C3H7O2.; C4: C4H9O2.; C5: C5H 11 O2.) and the T-FDCA probe specifically bind to form free radical adducts. By measuring the content of this type of adduct, we can further analyze the distribution of RO2 free radicals with different carbon numbers in the air (such as the distribution of short carbon chain (C1-C5) RO2 under different weather conditions). Figure 7 shown).

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fluorescent probe for detecting peroxyl radicals in the atmosphere, characterized in that: The fluorescent probe has the following chemical formula:

2. The method for preparing the fluorescent probe for detecting peroxyl radicals in the atmosphere according to claim 1, characterized in that: The steps include: (1) 2,5-furandicarboxylic acid and thionyl chloride are mixed and stirred, DMF is added as a reaction catalyst, and a reflux reaction is carried out under an inert gas environment and heating conditions. After cooling to room temperature, the reactant is evaporated to remove excess thionyl chloride to obtain a solid compound 1; (2) Compound 1 is dissolved in dichloromethane, and the yellow solution containing compound 1 is added dropwise to a dichloromethane solution containing the nitroxide free radical piperidinol, anhydrous sodium sulfate powder is added, and then pyridine is added as an acid binding agent, and the reaction is stirred under an inert gas environment, and then column chromatography is performed to obtain a solid product, which is a fluorescent probe.

3. The method for preparing a fluorescent probe for detecting peroxyl radicals in the atmosphere according to claim 2, characterized in that: In step (1), the dosage ratio of the 2,5-furandicarboxylic acid to thionyl chloride is 0.5 mol:1 L; the volume ratio of the thionyl chloride to DMF is 100:1, and the reflux reaction is refluxed at normal pressure and 70-80° C. for 3 h.

4. The method for preparing a fluorescent probe for detecting peroxyl radicals in the atmosphere according to claim 2, characterized in that: In step (2), the molar ratio of the nitroxide free radical piperidinol to compound 1 is 1:1; the concentration of compound 1 after being dissolved in dichloromethane is 0.5 mol / L; the molar ratio of anhydrous sodium sulfate to compound 1 is 1:2, and the molar ratio of pyridine to compound 1 is 1:1; the stirring reaction is carried out at room temperature for 12 hours.

5. The method for preparing a fluorescent probe for detecting peroxyl radicals in the atmosphere according to claim 2 or 4, characterized in that: In step (2), the column chromatography separation uses a mixed solvent of petroleum ether and ethyl acetate as an eluent, and the volume ratio of the petroleum ether to ethyl acetate is 4:

1.

6. The method for preparing a fluorescent probe for detecting peroxyl radicals in the atmosphere according to claim 2, characterized in that: The inert gas in step (1) and step (2) is nitrogen.

7. Use of the fluorescent probe according to claim 1 for detecting short-chain peroxyl free radicals in an atmospheric environment.

8. The application according to claim 7 is characterized in that the application of the fluorescent probe in the actual atmospheric environment is as follows: the fluorescent probe methanol solution is loaded on the surface of the glass fiber membrane, the prepared fluorescent probe membrane is placed on the atmospheric sampler, and air is passed through the fluorescent probe membrane under the external atmospheric environment. After the sampling is completed, the membrane components are dissolved in methanol and a fluorescence spectrum test is performed.

9. The use according to claim 8, characterized in that: The concentration of the fluorescent probe methanol solution is 10 mmol / L and the volume is 2 mL. During sampling, the flow rate of the air passing through the fluorescent probe membrane is 100 L / min.

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