A fluorescent probe for detecting trivalent arsenic ions, a preparation method and application thereof

Abstract

This invention provides a fluorescent probe for detecting trivalent arsenic ions, its preparation method, and its application. The fluorescent probe has a structural formula selected from at least one of Formula 1, Formula 2, Formula 3, or Formula 4. The fluorescent probe exhibits high fluorescence emission intensity, good sensitivity and response speed for detecting trivalent arsenic ions, and can achieve real-time dynamic analysis of trivalent arsenic ion concentration in situ.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of fluorescence probe for detecting trivalent arsenic ion, preparation method and application, belong to fluorescence probe technical field. BACKGROUND

[0002] Arsenic is a metal substance, belongs to class A human carcinogens, can enter human body through arsenic-containing water and edible crops. As one of the biggest environmental health hazards, about 300 million people in one-third of the world's population suffer from arsenic poisoning. In terms of the abundance of elements, the average concentration of arsenic in the earth's crust is about 3 mg / kg, and the average concentration of arsenic in seawater is about 1-2 μg / L. Arsenic can not only be released into the environment through geological processes, but also be released into the environment through various human activities, including smelting of arsenic-containing minerals, mining of sulfide ores, combustion of fossil fuels, drilling, industrial waste, arsenic-containing herbicides, petroleum refining, leather and wood processing, metal and alloy manufacturing ceramics manufacturing, etc. It mainly exists in two common oxidation states in water: arsenite (As (III)) and arsenate (As (V)), and the ratio of As (V) to As (III) fluctuates within the range of 10-100 according to the chemical environment, while the toxicity of arsenite is 25-60 times that of arsenate and has stronger mobility. Inorganic arsenic can cause chronic and acute toxicity. Among them, chronic arsenic poisoning can cause respiratory diseases, gastritis, colitis, anorexia, indigestion, hair loss and abdominal pain, etc. If long-term contact with arsenic through food or air can cause ischemic heart disease, hypertension, atherosclerosis and eczema, etc. Cardiovascular diseases; it may even cause liver cancer, lung cancer, kidney cancer, bladder cancer. In addition, arsenic can prevent DNA damage repair and inhibit lipid metabolism. Therefore, it is of great significance to develop efficient and sensitive trivalent arsenic ion detection methods.

[0003] At present, researchers have reported a variety of methods for detecting trivalent arsenic ions, among which the most commonly used is traditional instrument detection method, such as inductively coupled plasma mass spectrometry, capillary electrophoresis, high performance liquid chromatography and ion chromatography, etc. Due to the influence of factors such as complex sample pretreatment steps, expensive instruments and sample molecule destruction, the application of these methods in trivalent arsenic ion detection is limited to some extent. Compared with traditional trivalent arsenic ion detection methods, fluorescence molecular probe detection technology has the advantages of high detection sensitivity, good selectivity and simple operation, and has attracted widespread attention.

[0004] Aggregation-induced emission (AIE) is a unique photophysical phenomenon proposed by Academician Tang Benzhong in 2001. In recent years, this AIE phenomenon has been applied to the development of fluorescent probes, such as tetraphenyl ethylene, which has attracted widespread attention among various AIE-based fluorophores due to its excellent photophysical properties and good structural flexibility.

[0005] However, there are no reports in the existing technology regarding the use of aggregation-induced emission fluorescent probes for the detection of trivalent arsenic ions. Summary of the Invention

[0006] This invention provides a fluorescent probe for detecting trivalent arsenic ions, its preparation method, and its application, which can effectively solve the above-mentioned problems.

[0007] This invention is implemented as follows:

[0008] A fluorescent probe for detecting trivalent arsenic ions, the structural formula of which is selected from at least one of Formula 1, Formula 2, Formula 3 or Formula 4:

[0009]

[0010] The structural formula for R is as follows:

[0011]

[0012] As a further improvement, its structural formula is selected from at least one of Formula 1, Formula 2, Formula 3, and Formula 4:

[0013]

[0014] As a further improvement, its structural formula is:

[0015]

[0016] A method for preparing the above-mentioned fluorescent probe for detecting trivalent arsenic ions includes the following steps:

[0017] S1, TPE-4Br, CuCN and N,N-dimethylformamide DMF are added to the reaction vessel and heated to reflux to generate TPE-4CN;

[0018] S2, TPE-4CN, KOH and 1,2-ethylene glycol are added to the reaction vessel and heated under reflux to produce TPE-4COOH;

[0019] S3, under a nitrogen atmosphere, benzotriazole and thionyl chloride are reacted, and then TPE-4COOH is added to generate TPE-4Bt.

[0020] S4, under a nitrogen atmosphere, L-cysteine, triethylamine, MeCN and H2O are added sequentially to the reaction vessel. After stirring until homogeneous, TPE-4Bt is added, and the reaction produces TPE-4Cys.

[0021] As a further improvement, in step S1, the temperature of the heating reflux is [temperature value missing], and the time is 55-65 hours.

[0022] As a further improvement, in step S2, the temperature of the heating reflux is 110-130℃ and the time is 70-75h.

[0023] A method for detecting trivalent arsenic ions involves contacting solutions of trivalent arsenic ions at different concentrations with the aforementioned fluorescent probe, followed by fluorescence excitation and fluorescence intensity testing. A fluorescence titration curve of the trivalent arsenic ion concentration is then fitted. The fluorescence intensity of the sample to be tested is measured using the same method, and the concentration of trivalent arsenic ions in the sample to be tested is calculated based on the fluorescence titration curve.

[0024] As a further improvement, the excitation wavelength of the fluorescence excitation is 320–365 nm, preferably 325–335 nm.

[0025] As a further improvement, the cationic masking agent EGTA and the antioxidant L-ascorbic acid were added during the fluorescence intensity testing process.

[0026] As a further improvement, when the fluorescent probe is TPE-4Cys, the concentration of the fluorescent probe is 0.8-1.2×10⁻⁶. -5 M.

[0027] The beneficial effects of this invention are:

[0028] The present invention provides a method for detecting trivalent arsenic ions in water using a fluorescent probe. The fluorescent probe exhibits high sensitivity and selectivity, generating strong fluorescence upon binding with trace amounts of trivalent arsenic, which is visible to the naked eye under ultraviolet light. The detection limit for trivalent arsenic ions in water samples reaches 7.5 ppb. Furthermore, under 330 nm excitation light, the fluorescent probe shows significant fluorescence enhancement at 489 nm using a fluorescence spectrometer, and the intensity of this enhancement is proportional to the amount of trivalent arsenic within a certain range. This allows for the quantitative detection of trivalent arsenic ions in water, enabling real-time dynamic analysis of trivalent arsenic ion concentration in situ.

[0029] In the detection system of this invention, the concentration of the TPE-4Cys fluorescent probe used is 1.0 × 10⁻⁶. -5 At time M, the linear range for detecting trivalent arsenic ions was 7.5 ppb-1125 ppb.

[0030] The fluorescent probe synthesized in this invention was subjected to fluorescence testing with different metal ions added to pure water. EGTA was added as an ion shielding agent during the metal ion testing process. The specificity of the probe's response to trivalent arsenic ions was detected. The test results showed that the probe only has a specific response to trivalent arsenic anions. After the addition of EGTA, most metal ions did not affect the detection of trivalent arsenic, indicating that the fluorescent probe has high selectivity for trivalent arsenic. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 The synthesis reaction formula for TPE provided in Example 1 of this invention is shown.

[0033] Figure 2 The synthesis reaction formula for TPE-4Br provided in Example 1 of this invention is shown.

[0034] Figure 3 The synthesis reaction formula for TPE-4CN provided in Example 1 of this invention is shown.

[0035] Figure 4 The synthesis reaction formula for TPE-4COOH provided in Example 1 of this invention is shown.

[0036] Figure 5 The synthesis reaction formula for TPE-4Bt provided in Example 1 of this invention is shown.

[0037] Figure 6 The synthesis reaction formula for TPE-4Cys provided in Example 1 of this invention.

[0038] Figure 7 The UV-Vis spectrum and solution fluorescence excitation and emission spectra of the fluorescent probe TPE-4Cys provided in Example 2 of this invention are shown.

[0039] Figure 8 The UV-Vis spectra of the fluorescent probe TPE-4Cys provided in Example 2 of this invention before and after the addition of trivalent arsenic ions, the fluorescence titration curves and linear fitting curves under different trivalent arsenic ion concentration systems, are shown.

[0040] Figure 9 The response curves and bar charts of the fluorescent probe TPE-4Cys provided in Example 3 of this invention to different metal ion solutions after EGTA shielding are shown.

[0041] Figure 10 The response curves and bar charts of the fluorescent probe TPE-4Cys provided in Example 4 of this invention to different anion solutions are shown.

[0042] Figure 11 The bar chart shows the fluorescence response of the fluorescent probe TPE-4Cys provided in Example 5 of this invention under the coexistence conditions of As(III) and different anions.

[0043] Figure 12 The dynamic light scattering pattern and scanning electron microscope characterization image of the fluorescent probe TPE-4Cys and As(Ⅲ) solution after mixing are shown in Example 6 of this invention.

[0044] Figure 13 The image shows the 1H NMR spectrum of the fluorescent probe molecule TPE-4Cys provided in Example 1 of this invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] This invention provides a fluorescent probe for detecting trivalent arsenic ions, the structural formula of which is selected from at least one of Formula 1, Formula 2, Formula 3 or Formula 4:

[0047]

[0048] The structural formula of the R substituent is as follows:

[0049] The remaining substituents are independently selected from at least one of hydrogen, heteroatom, alkyl, unsaturated alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl.

[0050] The fluorescent probes in this invention are slightly soluble in water. When the fluorescent probes are freely dissolved in the aqueous solution, the active intramolecular motion of the fluorescent probe molecules, such as the rotational benzene ring dynamics in the propeller-shaped tetraphenylethylene derivative, greatly consumes the excited state energy of the molecules, causing the excited state energy to dissipate in the form of nonradiative transitions without emitting light. In the presence of trivalent arsenic ions, the fluorescent probe molecules react with trivalent arsenic ions and aggregate, which can effectively restrict the intramolecular motion of the probe molecules, thereby significantly enhancing photoluminescence.

[0051] L-cysteine ​​(L-Cys) consists of a thiol functional group (-SH) that specifically binds to arsenic, a carboxyl auxiliary coordinating group, and an amino bridging group. This composition increases the water solubility of the fluorescent probe molecule and provides a targeting group for arsenic binding. It is clearly shown that the free -SH group of L-cysteine ​​binds to As(III) via an As-S bond. Structural analysis of the formed complex shows that As(III) binds to three Cys groups, forming a trigonal pyramidal As(Cys)3 complex. Therefore, modifying the structure of the AIE luminescent source TPE with the arsenic-sensitive targeting functional group L-cysteine ​​enables specific in-situ sensitive detection of trivalent arsenic salts.

[0052] The fluorescent probe molecule in this invention can be used as a detector for trivalent arsenic ions, and has the advantages of high detection sensitivity, rapid response, and fluorescence visualization.

[0053] As a further improvement, its structural formula is selected from at least one of Formula 1, Formula 2, Formula 3, and Formula 4:

[0054]

[0055] As a further improvement, its structural formula is:

[0056]

[0057] This invention also provides a method for preparing the above-mentioned fluorescent probe for detecting trivalent arsenic ions, comprising the following steps:

[0058] S1, TPE-4Br, CuCN and N,N-dimethylformamide DMF are added to the reaction vessel and heated to reflux to generate TPE-4CN;

[0059] S2, TPE-4CN, KOH and 1,2-ethylene glycol are added to the reaction vessel and heated under reflux to produce TPE-4COOH;

[0060] S3, under a nitrogen atmosphere, benzotriazole and thionyl chloride are reacted, and then TPE-4COOH is added to generate TPE-4Bt.

[0061] S4, under a nitrogen atmosphere, L-cysteine, triethylamine, MeCN and H2O are added sequentially to the reaction vessel. After stirring until homogeneous, TPE-4Bt is added, and the reaction produces TPE-4Cys.

[0062] As a further improvement, in step S1, the temperature of the heating reflux is [temperature value missing], and the time is 55-65 hours.

[0063] As a further improvement, in step S2, the temperature of the reflux heating is 110-130℃ and the time is 70-75h.

[0064] This invention provides a method for detecting trivalent arsenic ions. Different concentrations of trivalent arsenic ion solutions are contacted with the aforementioned fluorescent probe, followed by fluorescence excitation and fluorescence intensity testing. A fluorescence titration curve of the trivalent arsenic ion concentration is fitted. The fluorescence intensity of the sample to be tested is measured using the same method. Based on the fluorescence titration curve, the concentration of trivalent arsenic ions in the sample to be tested is calculated.

[0065] The instruments used in this method include a portable UV lamp, stoppered quartz cuvettes, wash bottles, lens paper, pipettes, and other accessories, as well as fluorescence spectrometers, fiber optic spectrometers, and laser-induced fluorescence spectrometers. The portable UV lamp can provide a suitable wavelength excitation source at any time to detect the fluorescence response of the sample. The stoppered quartz cuvettes are used to observe the fluorescence response of the solution inside under UV excitation. The wash bottle is used to hold distilled or deionized water for cleaning the cuvettes after use. Lens paper is used for initial wiping after cleaning the cuvettes. The pipette is used to accurately aspirate the fluorescent probe solution and water sample to ensure the accuracy and repeatability of the experiment. The fluorescence spectrometer, fiber optic spectrometer, and laser-induced fluorescence spectrometer are used to detect the prepared water sample in real time, performing fluorescence intensity tests under their optimal excitation wavelengths.

[0066] As a further improvement, the excitation wavelength of the fluorescence excitation is 320–365 nm, preferably 325–335 nm.

[0067] As a further improvement, the cationic masking agent EGTA and the antioxidant L-ascorbic acid were added during the fluorescence intensity testing process. Adding an appropriate amount of EGTA solution to shield against interference from other metal ions can improve the probe's detection performance. Adding an appropriate amount of L-ascorbic acid can stabilize the trivalent arsenic content in the water sample.

[0068] As a further improvement, when the fluorescent probe is TPE-4Cys, the concentration of the fluorescent probe is 0.8-1.2×10⁻⁶. -5 M.

[0069] Example 1

[0070] TPE-4Cys synthesis steps:

[0071] 1) Synthesis of TPE.

[0072] Synthesis process: Under a nitrogen atmosphere and in an ice-water bath, zinc powder (7.2 g) and anhydrous THF (80 mL) were added to a 250 mL double-necked round-bottom flask. Then, TiCl4 (6 mL) was slowly added dropwise over 30 min. The flask was removed from the ice-water bath and refluxed at 80 °C for approximately 2 h. Under a nitrogen atmosphere, benzophenone (5.0 g) was dissolved in anhydrous THF (20 mL), and then slowly added to the flask using a syringe. The mixture was refluxed at 80 °C overnight. After the reaction was complete, the mixture was cooled to room temperature, quenched with HCl (2 wt%), and extracted with ethyl acetate and water (2 × 200 mL). The organic phase was collected, dried over anhydrous magnesium sulfate, and filtered. The solvent was removed by rotary evaporation under reduced pressure. The crude product was repeatedly washed with ethanol and filtered to obtain a white solid TPE in 80% yield. Its 1H NMR spectrum is as follows: 1H NMR (CDCl3, 400MHz): δ (ppm) 7.05-7.08 (m, 8H), 7.10-7.13 (m, 12H); 13 C NMR (CDCl3, 100MHz): δ (ppm) 126.6, 127.8, 131.5, 141.1, 143.9.

[0073] 2) Synthesis of TPE-4Br.

[0074] Synthesis process: Under ice bath conditions, tetraphenylethylene (5g), glacial acetic acid (30mL), and dichloromethane (30mL) were added to a two-necked round-bottom flask. A mixture of liquid bromine (12mL), glacial acetic acid (20mL), and dichloromethane (10mL) was injected into the flask over 20 minutes using a constant-pressure funnel. After reacting for 30 minutes, the ice bath was removed, and the reaction mixture was heated at 50°C for approximately 15 minutes. After the reaction was complete, Na₂S₂O₄ solution was added to remove residual liquid bromine, and the reaction mixture was poured into ice water. The precipitate was filtered to obtain a solid phase, which was repeatedly washed with water and ethanol to obtain a white initial product, TPE-4Br, with a yield of 43%. Its 1H NMR spectrum is as follows: 1 HNMR (CDCl3, 400MHz): δ (ppm) 7.27 (d, J = 8.5 Hz, 8H), 6.85 (d, J = 8.5 Hz, 8H).

[0075] 3) Synthesis of TPE-4CN.

[0076] Synthesis process: Under a nitrogen atmosphere, TPE-4Br (3g), CuCN (2.3g), and N,N-dimethylformamide (DMF) (22mL) were added to a double-necked round-bottom flask and refluxed at 150℃ for 60h. After the reaction was complete, the reaction solution was poured into 300mL of water, and 10mL of ethylenediamine was added. The resulting mixture was stirred at 100℃ for 1h and then filtered. The precipitated solid was extracted with dichloromethane (3×150mL), and the combined organic phases were dried over anhydrous magnesium sulfate. After filtration and solvent evaporation, the crude solid product was purified by silica gel chromatography (eluent: petroleum ether / dichloromethane = 1:5, Rf = 0.4) to obtain TPE-4CN as a white solid with a yield of 47%. Its 1H NMR spectrum is as follows: 1 H NMR (CDCl3, 400MHz): δ (ppm) 7.48 (t, J = 5.0Hz, 8H), 7.08 (t, J = 5.0Hz, 8H). HRMS (MALDI-TOF), m / z calcd.for C 30 H 16 N4:432.1375; found432.1379.

[0077] 4) Synthesis of TPE-4COOH.

[0078] Synthesis process: Under a nitrogen atmosphere, TPE-4CN (1.0 g), KOH (1.3 g), and 1,2-ethylene glycol (60 mL) were added to a double-necked flask and heated to 120 °C under reflux and stirring for 72 h. After the reaction was complete, the mixture was extracted and washed with dichloromethane (3 × 40 mL). The reaction solution was then poured into 40 mL of ice water, and the pH of the aqueous phase was adjusted to 1.0. The solid was collected by filtration and repeatedly washed with DCM and water to obtain a pale yellow solid product, TPE-4COOH, with a yield of 89%. Its 1H NMR spectrum is as follows: 1 H NMR (DMSO-d6, 400MHz): δ (ppm) 12.98 (s, 4H), 7.73 (d, J = 8.1 Hz, 8H), 7.11 (d, J = 8.1 Hz, 8H).

[0079] 5) Synthesis of TPE-4Bt.

[0080] Synthesis process: Benzotriazole (1.31 g) was added to a dry two-necked flask at room temperature under a nitrogen atmosphere, followed by the addition of dichloromethane (20 mL) and stirring to dissolve. Using a syringe, 0.2 mL of thionyl chloride was slowly added to the flask, and the reaction was allowed to proceed for 30 min. Then, 0.24 g of solid powder TPE-4COOH was added to the flask, and the reaction was allowed to proceed for 1 h. After the reaction was complete, 10 mL of 0.1 M sodium hydroxide solution was added to the reaction mixture, followed by extraction with dichloromethane (3 × 30 mL) and washing. The organic phase was dried over anhydrous Na₂SO₄ and then evaporated to dryness to obtain a yellow solid. The obtained solid was dissolved in a small amount of DCM and then slowly added dropwise to 30 mL of n-hexane. The precipitated bright yellow powder TPE-4Bt was collected, with a yield of 89%. Its 1H NMR spectrum is as follows: 1H NMR (CDCl3, 400MHz): δ (ppm) 8.37 (d, J = 8.3 Hz, 4H), 8.19-8.11 (m, 12H), 7.69 (d, J = 8.1 Hz, 4H), 7.57-7.51 (m, 4H), 7.37 (d, J = 8.2 Hz, 8H). 13 C NMR (CDCl3, 100MHz): δ (ppm) 167.6, 148.2, 145.9, 142.2, 132.5, 131.5, 130.7, 130.6, 126.6, 121.8, 116.1.

[0081] 6) Synthesis of TPE-4Cys.

[0082] Synthesis process: Under a nitrogen atmosphere at room temperature, L-cysteine ​​(0.12 g), triethylamine (0.14 mL), MeCN (3 mL), and H2O (1 mL) were added sequentially to a two-necked flask and stirred until homogeneous. Then, bright yellow solid TPE-4Bt (0.19 g) was added and reacted for 6 h. After the reaction was complete, 5 mL of water was added for dilution, and the solution was acidified dropwise with 1 M HCl to pH = 2. 10 mL of anhydrous diethyl ether was added and sonicated to ensure complete dispersion. The precipitate was obtained by filtration and washed sequentially with water, anhydrous diethyl ether, and DCM. The precipitate was then dried to obtain a pale yellow powder, TPE-4Cys, with a yield of 76%. Its 1H NMR spectrum is as follows: 1 H NMR (DMSO-d6, 400MHz): δ (ppm) 12.84 (s, 4H), 8.63 (d, J = 7.8Hz, 4H), 7.74 (d, J = 8.3Hz, 8H), 7.15 (d, J = 8.2Hz, 8H), 4 .49-4.43(m,4H),2.98(dd,J=13.2,8.5,4.4Hz,4H),2.84(dt,J=13.5,8.8,8.8Hz,4H),2.58(t,J=8.4,8.4Hz,4H). 13CNMR (DMSO-d6, 100MHz): δ (ppm) 173.7, 165.8, 145.4, 137.1, 132.7, 131.2, 127.1, 55.6. The 1H NMR spectrum of TPE-4Cys is shown below. Figure 13 As shown.

[0083] Example 2

[0084] Preparation of fluorescent probe stock solution: Accurately weigh the solid probe sample TPE-4Cys prepared in Example 1 and dissolve it in dimethyl sulfoxide solution to prepare a solution with a concentration of 1.0 × 10⁻⁶. -3 Mother liquor of M.

[0085] Use a pipette to draw 20.0 μL (1.0 × 10⁻⁶) of the solution. -3 Add M)TPE-4Cys solution to a 2mL stoppered four-way quartz cuvette, then pipette 1980μL of pure water into the cuvette. Stir and vortex to mix thoroughly, ensuring the solution is clear and transparent, without any visible suspended matter. Next, initially irradiate the cuvette with a 365nm handheld UV lamp to observe the solution's properties. Then, transfer the solution to a fluorescence spectrometer and set the optimal excitation wavelength to 330nm. Maximum emission should occur at 489nm, which can be used for comparison. Figure 8 As shown.

[0086] Use a pipette to draw 20.0 μL (1×10⁻⁶) of liquid. -3 Add M)TPE-4Cys solution to a 2 mL stoppered four-way quartz cuvette. Then, pipette 980 μL of pure water sample into the cuvette, stir and vortex to mix thoroughly, ensuring the solution is clear and transparent with no visible suspended matter. Next, pipette 1000 μL of different concentration gradients (0-1×10⁻⁶) of the solution. -4 M)As(III) solution was added to the above cuvette; then, the cuvette was irradiated with a handheld UV lamp with a wavelength of 365 nm, and the fluorescence of the solution was observed. Visible blue-green fluorescence was observed in the cuvette, indicating the presence of trivalent arsenic ions in the solution. The cuvette was then moved to a fluorescence spectrometer and excited with excitation light at the optimal excitation wavelength of 330 nm. Maximum emission was observed at 489 nm, allowing for the quantitative detection of the trivalent arsenic ion concentration in the water sample. The test results are attached. Figure 8 As shown in B and 8C, the fluorescence intensity gradually increases with the increase of trivalent arsenic ion content. The final concentration of the TPE-4Cys fluorescent probe used is 1.0 × 10⁻⁶. -5 M has a linear range of 7.5 ppb-1125 ppb for detecting trivalent arsenic ions, and a detection limit of 7.5 ppb for trivalent arsenic ions in water samples. The linear equation is y = 149.48 + 307.26x.

[0087] The UV-Vis test results were obtained by testing the probe solution before and after the addition of As(III). Figure 8 As shown in Figure A, a distinct tailing phenomenon is formed in the 400-700 nm range, which may be the result of Rayleigh scattering caused by the formation of aggregates between the probe and As(III).

[0088] Example 3

[0089] In a four-way cuvette, take 20.0 μL (1×10⁻⁶) -3 M)TPE-4Cys was dissolved in 1920 μL of pure water, and 60 μL (1 × 10⁻⁶) of a solution containing the cationic shielding agent EGTA was added to the above probe solution. -3 M) metal salt solution (Na) + ,K + Ca 2+ Mg 2+ ,Mn 2+ Zn 2+ Cu 2+ Hg 2+ Pb 2+ Ni 2+ Cd 2+ ,Fe 2+ Co 2+ ,Fe 3+ And Al 3+ The fluorescence intensity changes of As(III) solutions were measured using a fluorescence spectrometer with the optimal excitation wavelength (330 nm for TPE-4Cys). The test results are attached. Figure 9 As shown in the figure. The results indicate that the probe exhibits a specific response only to As(III) ions in metal salt ions. The above test results demonstrate that the probe has good selectivity for trivalent arsenic ions.

[0090] Example 4

[0091] In a four-way cuvette, take 20.0 μL (1.0 × 10⁻⁶) of the solution. -3 M)TPE-4Cys was dissolved in 1920 μL of pure water, and 60.0 μL (1×10⁻⁶) of each solution was added. -3 M) Different anion salt solutions (As(III), As(V), Cl) - ,Br - I - NO3 - HCO3 - SO4 2- SO3 2- S 2- After thorough mixing, the fluorescence intensity change of the solution was measured using a fluorescence spectrometer with the optimal excitation wavelength of 330 nm. The test results are attached. Figure 10As shown. The results indicate that among many anions, the probe only exhibits a lighting response to As(III).

[0092] Example 5

[0093] In a four-way cuvette, take 20.0 μL (1.0 × 10⁻⁶) of the solution. -3 M)TPE-4Cys was dissolved in 1860 μL of pure water, and 60.0 μL of LAs(III) solution (1×10) was added. -4 M) and 60 μL (1×10 -3 M) Different anion salt solutions (As(V), Cl) - ,Br - I - NO3 - HCO3 - SO4 2- SO3 2- S 2- After thorough mixing, the fluorescence intensity change of the solution was measured using a fluorescence spectrometer with the optimal excitation wavelength of 330 nm. The test results are attached. Figure 11 As shown, the probe can achieve sensitive detection of trivalent arsenic ions even when coexisting with different anions.

[0094] Example 6

[0095] Take 20.0 μL (1×10 -3 M)TPE-4Cys and 20.0μL (1×10 -4 M)As(III) was dissolved in 1960 μL of pure water, mixed thoroughly, and then subjected to dynamic light scattering test experiments, as shown in the attached figure. Figure 12 As shown, the results indicate that the nanoparticles formed after the reaction of the probe TPE-4Cys with As(III) have a size of approximately 346 nm. After the above solution was dropped onto a silicon wafer and evaporated to dryness, it was characterized by scanning electron microscopy. The results showed that the particle size formed by the probe and As(III) was approximately 300 nm, consistent with the dynamic light scattering test results. This further indicates that the probe reacts with As(III) to form micro- and nano-aggregates.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluorescent probe for detecting trivalent arsenic ions, characterized by, The structural formula is: 。 2. A method for preparing the fluorescent probe for detecting trivalent arsenic ions according to claim 1, characterized by, The method comprises the following steps: S1, TPE-4Br, CuCN and N, N-dimethylformamide DMF are added into a reaction container, heated to reflux, and TPE-4CN is generated by reaction; S2, TPE-4CN, KOH and 1, 2-ethanediol are added into a reaction container, heated to reflux, and TPE-4COOH is generated by reaction; S3, under the atmosphere of nitrogen, benzotriazole and dichlorosulfoxide are reacted, then TPE-4COOH is added, and TPE-4Bt is generated by reaction; S4, under the atmosphere of nitrogen, L-cysteine, triethylamine, MeCN and H2O are sequentially added into a reaction container, stirred uniformly, then TPE-4Bt is added, and TPE-4Cys is generated by reaction; In step S2, the temperature of heating to reflux is 110-130 DEG C, and the time is 70-75 h.

3. A method of detecting trivalent arsenic ions, characterized by, The fluorescence intensity is tested after the fluorescence excitation, the fluorescence titration curve of the concentration of trivalent arsenic ions is fitted, the fluorescence intensity of the sample to be measured is determined by the same method, the concentration of trivalent arsenic ions in the sample to be measured is calculated according to the fluorescence titration curve; the excitation wavelength of the fluorescence excitation is 320-365 nm; in the process of testing the fluorescence intensity, the cation masking agent EGTA and / or L-ascorbic acid are also added.

4. The method of claim 3, wherein, The excitation wavelength of the fluorescence excitation is 325-335 nm.

5. The method of claim 3, wherein, When the fluorescent probe is TPE-4Cys, the concentration of the fluorescent probe is 0.8-1.2x10 -5 M.

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