Fluorescent probe for detecting isoprene peroxy radical, preparation method and application
By preparing and immobilizing a fluorescent probe for the detection of isoprene peroxide radicals, the problem of complex and expensive atmospheric free radical detection in existing technologies has been solved, and high-sensitivity and low-cost isoprene peroxide radical concentration detection has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LANZHOU UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-24
AI Technical Summary
Existing atmospheric free radical detection technologies require expensive instruments and complex techniques, are difficult to perform mobile measurements, and are easily affected by interference during actual field measurements, making it impossible to effectively detect the concentration of isoprene peroxide free radicals in the atmosphere.
A fluorescent probe for detecting isoprene peroxide radicals was developed. The fluorescent probe was prepared by reacting 2,5-furandicarboxylic acid with thionyl chloride and then with dihydroxyindole. The probe was then immobilized on a glass fiber membrane to form a fluorescent probe membrane. The concentration of free radicals was determined by the fluorescence intensity.
It achieves high sensitivity and strong anti-interference ability in the detection of isoprene peroxide radicals, can accurately detect concentration in complex atmospheric environments, and is low in cost and simple to operate.
Smart Images
Figure CN122444741A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of free radical detection methods, and particularly relates to a fluorescent probe for the detection of isoprene peroxide free radicals, its preparation method, and its application. Background Technology
[0002] In recent years, with the use of electric vehicles and new energy sources, my country has effectively controlled emissions from vehicle exhaust and industrial waste gas, resulting in a significant improvement in regional air quality. However, issues such as near-surface ozone and the increase of secondary air pollutants still urgently need to be addressed. Atmospheric peroxide free radicals play a crucial role in the growth of pollutants, necessitating in-depth research.
[0003] Peroxy radicals (RO2., where R is any organic group) are a major source of secondary air pollutants in the troposphere and are considered important intermediates in the atmospheric free radical transformation cycle. Atmospheric peroxy radicals are generally recognized to originate primarily from the atmospheric oxidation of volatile organic compounds (VOCs). Isoprene (C5H8) is the most important naturally occurring VOC in the atmosphere, and its oxidation process has a decisive impact on global atmospheric oxidation, ozone formation, and the formation of secondary organic aerosols. The oxidation of isoprene produces RO2. radicals ISOP34O2, with a molecular weight of 117 and the chemical formula C5H9O3., which are also considered representative species of naturally occurring RO2 radicals. Due to their central role in key reaction pathways, they have become a hot topic and a challenge in atmospheric chemistry research in recent years. Therefore, understanding and detecting the photochemical reaction and transformation mechanisms of atmospheric isoprene peroxy radicals is crucial for protecting public health and breaking the atmospheric free radical pollution cycle.
[0004] Currently available atmospheric free radical detection technologies include electron spin resonance, chemical amplification, laser-induced fluorescence, and chemical ionization mass spectrometry. However, these methods often require expensive instruments and complex techniques, making it difficult to perform mobile measurements. Furthermore, actual field measurements are subject to significant interference.
[0005] Compared to the techniques mentioned above, the advantage of chemiluminescent probe methods lies in their potential ability to capture free radicals by specific species. Because the probe structure often reacts specifically with only one type or class of free radicals, it is less susceptible to the influence of other atmospheric oxide species. Furthermore, the free radical adducts formed by the probe and the free radical retain the structural information of the original peroxide radical's R group. This provides a foundation for further research into the distribution of atmospheric peroxide radical species. In addition, chemiluminescent probe methods are simple to operate and convenient to collect data, avoiding the complex assembly and handling processes of the aforementioned instruments. Therefore, developing a fluorescent probe and corresponding sampling method suitable for the detection of atmospheric isoprene peroxide radicals is of significant value and importance for this detection. Summary of the Invention
[0006] Based on the above analysis, this application provides a fluorescent probe for detecting isoprene peroxide radicals, its preparation method, and its application. By providing an environmentally friendly, highly sensitive, and selective fluorescent probe, it offers a new and convenient means and method for detecting peroxide radicals in the atmospheric environment.
[0007] To achieve the above objectives, the first technical solution of this application discloses a fluorescent probe for detecting isoprene peroxide radicals, which has the following structural formula:
[0008] .
[0009] Furthermore, the method for preparing the aforementioned fluorescent probe for isoprene peroxide radical detection is characterized by comprising the following steps:
[0010] S1. React 2,5-furandicarboxylic acid with thionyl chloride to give 2,5-furandicarboxylic acid chloride;
[0011] S2. React 2,5-furandicarboxylic acid chloride with dihydroxyindole to obtain isoprene fluorescent probe for the detection of peroxy radicals.
[0012] Furthermore, the molar ratio of 2,5-furandicarboxylic acid to thionyl chloride is 1:5~15, and the molar ratio of 2,5-furandicarboxylic acid chloride to dihydroxyindole is 1:0.91~1.
[0013] The second technical solution of this application discloses a fluorescent probe membrane on which the above-mentioned fluorescent probe for detecting isoprene peroxide radicals is immobilized.
[0014] Furthermore, the method for preparing the aforementioned fluorescent probe membrane includes using a glass fiber membrane as a carrier, and electrospinning a solution containing the fluorescent probe for detecting isoprene peroxide radicals as described in claim 1 and polyvinylpyrrolidone to obtain the fluorescent probe membrane through electrospinning.
[0015] Furthermore, the mass ratio of the fluorescent probe for isoprene peroxide radical detection to polyvinylpyrrolidone is 1:15~19.
[0016] Furthermore, in the electrospinning process, the spinning injection speed is 0.3~0.5mL / h, and the needle voltage is 12~16KV.
[0017] The third technical solution of this application discloses the application of the above-mentioned fluorescent probe for detecting isoprene peroxide radicals or the above-mentioned fluorescent probe membrane in detecting the concentration of isoprene peroxide radicals in the atmospheric environment.
[0018] Furthermore, the fluorescent probe for detecting isoprene peroxide radicals or the fluorescent probe membrane is used to capture isoprene peroxide radicals in the atmosphere. After the capture is completed, fluorescence spectroscopy is performed, and the concentration of isoprene peroxide radicals in the atmosphere is determined by the intensity of the fluorescence.
[0019] Beneficial effects: The fluorescent probe for isoprene peroxide radicals provided in this application has high sensitivity, good repeatability and strong anti-interference ability when detecting the concentration of isoprene peroxide radicals in the atmospheric environment; when it is fixed on a carrier to prepare a fluorescent probe membrane, it can be applied to the detection of isoprene peroxide radical concentration under actual complex atmospheric conditions. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a chemical structure diagram of the fluorescent probe of this application;
[0022] Figure 2 This is the hydrogen NMR spectrum of the fluorescent probe in this application;
[0023] Figure 3 This is a diagram illustrating the capture reaction process of isoprene peroxy free radicals in the atmosphere by the fluorescent probe of this application.
[0024] Figure 4 This is the mass spectrum of the fluorescent probe and free radical adduct of this application;
[0025] Figure 5 This is a schematic diagram of the capture test process of simulated isoprene peroxide free radicals by the fluorescent probe of this application;
[0026] Figure 6 These are fluorescence spectra captured by the fluorescent probe membrane under various concentrations of isoprene peroxide radicals; among them, Figure 6 a is the fluorescence spectrum. Figure 6 b is a graph showing the linear relationship between fluorescence intensity and the amount of isoprene added;
[0027] Figure 7 This is the result of the fluorescence effect of each species on the probe adduct during the reaction process. Detailed Implementation
[0028] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.
[0029] The first embodiment of this application discloses a fluorescent probe for detecting isoprene peroxide radicals, which has the following structural formula:
[0030] .
[0031] like Figure 1 The chemical formula of the fluorescent probe is disclosed as C14H7NO5, with a relative molecular mass of 269.03; and its proton NMR spectrum is also disclosed (the proton NMR spectrum is shown in Figure 1). Figure 2 (As shown) and its carbon spectrum, according to the general nomenclature standard, it is named furan dicarboxylic acid-5,6-indole dicyclic ester, denoted as IND-F.
[0032] The preparation method of the above-mentioned fluorescent probe (5,6-indole dicyclic furanyl ester, IND-F) is then disclosed:
[0033] S1. React 2,5-furandicarboxylic acid with thionyl chloride to give 2,5-furandicarboxylic acid chloride;
[0034] S2. React 2,5-furandicarboxylic acid chloride with dihydroxyindole to obtain isoprene fluorescent probe for the detection of peroxy radicals.
[0035] Furthermore, the molar ratio of 2,5-furandicarboxylic acid to thionyl chloride is 1:14, and the molar ratio of 2,5-furandicarboxylic acid chloride to dihydroxyindole is 1:1.
[0036] In the above embodiments, the S1 reaction step can use DMF (N,N-dimethylformamide) as a catalyst, the reaction is carried out in an oil bath at 80°C, and the reaction time is preferably 5 hours. After the reaction is completed, a pale yellow clear liquid is obtained. Excess thionyl chloride is removed by vacuum distillation to obtain a crystalline pale yellow solid, namely the reaction product 2,5-furandicarboxylic acid chloride.
[0037] In a further embodiment, the S2 reaction step can be carried out using dichloromethane as a solvent and triethylamine as an acid-binding agent, and the reaction is carried out under nitrogen protection by stirring for 12 hours to obtain the crude fluorescent probe.
[0038] The crude fluorescent probe solution was purified to obtain light yellow crystals, which are 5,6-indole dicyclic furanyl dicarboxylate.
[0039] In the above embodiments, the purification can be carried out by vacuum filtration, followed by ethyl acetate extraction, silica gel column separation, etc., to obtain a purified product with the target purity.
[0040] The second embodiment of this application discloses a fluorescent probe membrane on which the aforementioned fluorescent probe for detecting isoprene peroxide radicals is immobilized. Furthermore, the method for preparing the fluorescent probe membrane includes using a glass fiber membrane as a carrier, mixing and stirring the fluorescent probe for detecting isoprene peroxide radicals with polyvinylpyrrolidone to obtain an electrospinning solution, and then electrospinning the solution to obtain the fluorescent probe membrane.
[0041] The third technical solution of this application discloses the application of the above-mentioned fluorescent probe for detecting isoprene peroxide radicals or the above-mentioned fluorescent probe membrane in detecting the concentration of isoprene peroxide radicals in the atmospheric environment.
[0042] like Figure 3 The process of the fluorescent probe described in this application capturing isoprene peroxide radicals in the atmosphere is disclosed.
[0043] RO2 is generated during the oxidation of isoprene. . The free radical ISOP34O2 has a molecular weight of 117, a chemical formula of C5H9O3, and a structural formula of CH2=C(CH3)CH2(OH)CH2-OO·. Figure 3 As shown, during the capture process, the indole imine of the fluorescent probe furanyl dicarboxylic acid-5,6-indole dicyclic ester (IND-F) molecule disclosed in this application first undergoes electrostatic attraction with the peroxy bond of ISOP34O2 to form a NO bond. Subsequently, the carbon-carbon double bond at the ortho position of the indole imine undergoes electrophilic addition with the hydroxyl group within the ISOP34O2 molecule to form a CO bond and obtain a cyclic adduct structure. During this process, one molecule of water is removed, and the final reaction yields a free radical adduct (i.e., IND-F-ISO). Figure 4 The mass spectra of the fluorescent probe and the free radical adduct are shown below.
[0044] The fluorescence reaction product was then subjected to fluorescence spectroscopy, and the concentration of isoprene peroxide radicals in the atmosphere could be determined by the intensity of the fluorescence.
[0045] The fluorescent probe, fluorescent probe film, and their applications of this application will be described in detail below through specific embodiments.
[0046] Example 1: Preparation of a fluorescent probe (IND-F) for the detection of isoprene peroxide radicals.
[0047] (1) Take 10 mmol of 2,5-furandicarboxylic acid (1.56 g) and add 10 mL of thionyl chloride and stir to mix. Add 0.1 mL of LDMF as a catalyst and stir in an oil bath at 80 °C for 5 h. The reaction yields a pale yellow clear liquid. Remove excess thionyl chloride by vacuum distillation to obtain a crystalline pale yellow solid (compound 1,2,5-furandicarboxylic acid chloride).
[0048] (2) Dissolve the above compound 1 (10 mmol, 1.91 g) in 10 mL of dichloromethane for later use, and designate it as solution A. At the same time, dissolve 10 mmol of dihydroxyindole (1.49 g) in 10 mL of dichloromethane and add 0.5 mL of triethylamine (acid-binding agent). Add solution A dropwise and stir for 12 h under nitrogen protection to obtain crude fluorescent probe (IND-F, furanyl dicarboxylic acid-5,6-indole dicyclic ester).
[0049] (3) The above crude fluorescent probe solution was filtered under reduced pressure and the solvent was evaporated. Ethyl acetate was added for extraction. The extract was evaporated and loaded onto a silica gel column for purification and separation (ethyl acetate / petroleum ether 0:1 → 5:5). The purified IND-F fluorescent probe was obtained as a light yellow crystal. MS (EI): 269.03: [M+H]+: 270.02.
[0050] Example 2: Preparation of fluorescent probe membrane (IND-F fluorescent membrane)
[0051] (4) Take 10 mL of 10 mmol / L IND-F methanol solution, add 0.5 g polyvinylpyrrolidone (130 WM) and mix for 2 h. Inject the resulting solution into two 5 mL syringes.
[0052] (5) Place six circular glass fiber membranes (90 mm) on the receiving shaft as supports. The spinning conditions are as follows: negative voltage (-2.0 KV), positive voltage (12.0 KV), shaft spacing 20 cm, pushing speed 0.5 mL / h, 18 G needle, and receiving speed 50 r / min. The prepared fluorescent probe membrane is sealed to isolate it from air and left for use.
[0053] Example 3: Application of fluorescent probe membranes
[0054] (1) such as Figure 5As shown, a particulate oxidation reaction tube was used as the gaseous free radical generation device. Under conditions of 40% relative humidity and 25℃, with zero air as the gas source, a 185nm ultraviolet lamp (10V, 20W) was used to generate sufficient hydroxyl radicals. Liquid isoprene was vaporized and reacted with the hydroxyl radicals to generate isoprene peroxide radicals (ISOP34O2). The concentration of isoprene peroxide radicals (≈2-8ppt) was changed by adjusting the concentration of gaseous isoprene (5-20ppb). Simultaneously, the effects of other species (including ozone, hydroxyl radicals, and other simulated types of free radicals such as low-carbon peroxide radicals, toluene peroxide radicals, and α-pinene radicals) on the probe fluorescence were tested.
[0055] (2) Install an atmospheric sampler at the outlet of the oxidation tube, place the fluorescent probe membrane inside the sampler, and collect samples for 1 hour at a sampling rate of 20 L / min after the free radicals have stabilized.
[0056] (3) After collecting the probe membrane, it was chopped and dissolved in 10 mL of methanol. After ultrasonic-assisted dissolution for 5 min, fluorescence emission spectroscopy was performed (wavelength range 200-800 nm, excitation wavelength 490 nm, emission slit width and receiving slit width are both 10 nm). The fluorescence spectra of the fluorescent probe membrane with isoprene peroxide radicals of various concentrations are shown in the figure. Figure 6 As shown: it can be seen that with the increase of the isoprene peroxide free radical concentration gradient, the fluorescence intensity of the probe membrane after capture increases accordingly. Figure 6 a), and exhibits a good linear relationship ( Figure 6 b), The influence of each species on the fluorescence of the probe adduct during the reaction is shown in [reference needed]. Figure 7 The results indicate that ozone, hydroxyl radicals, and other types of free radicals generated by the control simulation during the reaction process have no significant effect on the determination of isoprene peroxy radicals in the atmosphere by the probe membrane (based on the fact that the signal-to-noise ratio of the species response is less than 3 except for isoprene peroxy radicals).
[0057] The core of this fluorescent probe lies in its specific capture ability of atmospheric isoprene peroxide radicals. Compared with chemical ionization mass spectrometry (CISMS), which can detect isoprene peroxide radicals, the fluorescent probe described in this application offers a more economical and convenient detection method with lower cost. Actual field testing of the fluorescent probe membrane obtained in Example 2 of this application (Table 1 shows some field testing results) revealed a quantitative detection limit of 0.59 ppt (signal-to-noise ratio of 10). Currently, the detection limits of CISMS for atmospheric isoprene peroxide radicals are all 1 ppt or higher. Therefore, the fluorescent probe of this application exhibits superior technical performance in the specific detection of atmospheric isoprene peroxide radicals.
[0058] Table 1. Partial Field Testing Results
[0059] 01-04 10:00-12:00 0.63 0.06 107 88 2 14 95 9.82 67.1 01-04 12:00-14:00 0.64 0.03 81 64 3 19 87 9.87 63.0 01-04 14:00-16:00 0.87 0.03 38 28 2 8 90 10.65 61.2 01-04 16:00-18:00 0.38 0.03 45 33 2 11 91 10.22 70.0 01-05 10:00-12:00 0.75 0.02 85 68 2 7 75 8.58 75.5 01-05 12:00-14:00 0.74 0.02 53 42 2 8 96 10.05 67.6 01-05 14:00-16:00 0.51 0.02 38 30 2 9 99 9.84 67.5 01-05 16:00-18:00 0.84 0.02 57 46 2 8 82 7.80 78.2 01-06 08:00-10:00 0.86 0.02 71 62 -- 14 69 6.40 77.2 01-06 10:00-12:00 0.62 0.02 66 55 1 15 80 7.54 71.1 01-06 12:00-14:00 0.44 0.02 54 45 1 16 67 8.84 71.4 01-06 14:00-16:00 0.80 0.03 54 43 1 19 71 7.92 72.0 01-06 16:00-18:00 1.08 0.03 76 58 -- 30 48 6.59 79.0
[0060] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A fluorescent probe for detecting isoprene peroxide radicals, having the following structural formula: 。 2. The method for preparing the fluorescent probe for isoprene peroxide radical detection according to claim 1, characterized in that, Includes the following steps: S1. React 2,5-furandicarboxylic acid with thionyl chloride to give 2,5-furandicarboxylic acid chloride; S2. React 2,5-furandicarboxylic acid chloride with dihydroxyindole to obtain isoprene fluorescent probe for the detection of peroxy radicals.
3. The preparation method according to claim 2, characterized in that, The molar ratio of 2,5-furandicarboxylic acid to thionyl chloride is 1:5~15, and the molar ratio of 2,5-furandicarboxylic acid chloride to dihydroxyindole is 1:0.91~1.
4. A fluorescent probe membrane, characterized in that, The membrane is immobilized with the fluorescent probe for detecting isoprene peroxide radicals as described in claim 1.
5. The method for preparing the fluorescent probe membrane according to claim 4, characterized in that, The method includes using a glass fiber membrane as a carrier, and electrospinning a solution containing the fluorescent probe for detecting isoprene peroxide radicals as described in claim 1 and polyvinylpyrrolidone to obtain a fluorescent probe membrane through electrospinning.
6. The preparation method according to claim 5, characterized in that, The mass ratio of the fluorescent probe for detecting isoprene peroxy radicals to polyvinylpyrrolidone is 1:15~19.
7. The preparation method according to claim 5, characterized in that, In the electrospinning process, the spinning injection speed is 0.3~0.5mL / h, and the needle voltage is 12~16KV.
8. The application of the fluorescent probe for detecting isoprene peroxide radicals according to claim 1 or the fluorescent probe membrane according to claim 4 in detecting the concentration of isoprene peroxide radicals in the atmospheric environment.
9. The application according to claim 8, characterized in that, The fluorescent probe for detecting isoprene peroxide radicals as described in claim 1 or the fluorescent probe membrane as described in claim 4 is used to capture isoprene peroxide radicals in the atmosphere. After the capture is completed, fluorescence spectroscopy is performed, and the concentration of isoprene peroxide radicals in the atmosphere is determined by the intensity of the fluorescence.