Fluorescent probe material based on Mn coordination polymer and application of fluorescent probe material in norfloxacin detection

Abstract

The invention provides a Mn coordination polymer-based fluorescent probe material and application thereof in norfloxacin detection, and belongs to the technical field of fluorescent sensing. The chemical structural unit of the Mn coordination polymer (Mn-CP) fluorescent probe material is [Mn5 (ClL) 3 (H2O) 3], wherein (ClL) 4 <-> is synchronously formed by a self-made ligand 5-(3-carboxyl-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid (H3L) in the coordination reaction process of the self-made ligand 5-(3-carboxyl-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid (H3L) and MnCl2. 4H2O. The Mn-CP is prepared by the following method: dissolving manganese chloride and H3L in acetonitrile and H2O solvents, and then heating to react. The three-dimensional Mn-CP fluorescent probe material disclosed by the invention is simple in preparation method, low in cost and good in fluorescence stability. When being used for detecting norfloxacin in a water body, the compound shows excellent recognition performance, is good in stability, and is green and environment-friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of fluorescent sensing, and relates to a Mn coordination polymer fluorescent probe material, in particular to a three-dimensional Mn-CP fluorescent probe material, a preparation method thereof and application of the Mn-CP fluorescent probe material in recognizing norfloxacin. BACKGROUND

[0002] Norfloxacin, as a widely used fluoroquinolone antibiotic, plays an important role in human medical treatment and livestock breeding. However, the residue problem caused by its overuse has caused serious environmental and health risks: not only polluting water and soil, but also possibly being transmitted through the food chain, inducing bacterial resistance and threatening human health. Existing detection methods such as chromatography are accurate, but they rely on expensive equipment and complex pretreatment, which cannot meet the demand of on-site rapid screening. Fluorescent recognition sensing technology provides an innovative solution for norfloxacin trace detection with its high sensitivity, strong selectivity, convenient operation and real-time response. Developing efficient fluorescent probes not only has urgent practical significance for environmental pollution control and food safety supervision, but also will promote the progress of precise analysis methods and provide key scientific support for the prevention and control of antibiotic abuse.

[0003] Metal-organic frameworks (CPs) as fluorescent probe materials have the following core advantages: 1. Strong structural designability: by adjusting the combination of metal ions and organic ligands (such as carboxylic acids and nitrogen-containing heterocycles), the pore size, surface functional groups and luminescent properties of CPs can be precisely customized to achieve "lock and key recognition" of specific pollutants. 2. High sensitivity and rapid response: the rigid framework of CPs can effectively suppress fluorescence quenching, and the open pores can make the target substances diffuse rapidly and interact specifically (such as coordination and π-π stacking), resulting in significant changes in fluorescence intensity / wavelength, with a detection limit of ppb level and a response time of seconds to minutes. 3. Outstanding anti-interference ability: in complex matrices (such as wastewater and biological fluids), CPs can effectively exclude background interference through size screening effect (such as confined pores) or chemical selective adsorption, achieving specific detection of trace pollutants. 4. Environmental friendliness and low pollution synthesis: commonly using solvent thermal method, avoiding high energy consumption process. SUMMARY

[0004] The application aims to solve the above problems in the prior art, and provides a Mn coordination polymer (Mn-CP) fluorescent probe material, a preparation method thereof and application of the Mn-CP fluorescent probe material in recognizing norfloxacin. The Mn-CP fluorescent probe material shows high sensitivity, stability, anti-interference ability and recyclability in detecting norfloxacin in water, and the preparation method is simple, low in cost and environmentally friendly.

[0005] The technical scheme adopted by the present application is: the chemical structural unit of the Mn-CP fluorescent probe material is [Mn5(ClL)3(H2O)3], and the molecular formula is [Mn5(ClL)3(H2O)3] n ·6n(CH3CN).

[0006] Among them, (ClL) 4- is a self-made ligand 5-(3-carboxyl-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid (H3L) formed synchronously in the coordination reaction process of the ligand with MnCl2·4H2O. Z hexagonal system P 63 / m crystallized in a space group, and the cell parameters are: a = 20.4785(2) Å, b = 20.4785(2) Å, c = 11.16810(10) Å, α = 90°, β = 90°, gamma = 120°.

[0007] The structural formula of H3L is as follows: ; Further, a preparation method of the 5-(3-carboxyl-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid (H3L) is provided, comprising the following steps: (I) heating and refluxing 2-hydroxy-4-oxo-4-(p-tolyl)-2-butenoic acid ethyl ester and 5-hydrazinyl isophthalic acid in anhydrous ethanol, collecting brown solid powder, washing and drying to obtain 5-(3-(ethoxycarbonyl)-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid; (II) continuing to reflux the brown solid powder obtained in step (I) with NaOH, then adding hydrochloric acid dropwise until the solid precipitates, and then filtering, washing and drying to obtain the organic ligand 5-(3-carboxyl-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid.

[0008] Preferably, the molar ratio of the 2-hydroxy-4-oxo-4-(p-tolyl)-2-butenoic acid ethyl ester to the 5-hydrazinyl isophthalic acid in step (I) is 1-1.1:1-1.1; Preferably, the heating and refluxing time in step (I) is 24-48 h; Preferably, the washing in step (I) is performed by using deionized water; Preferably, the drying method in step (I) is normal temperature drying. As preferred, the molar ratio of the 5-(3-(ethoxycarbonyl)-5-(p-tolyl)-1H-pyrazol-1-yl) isophthalic acid to NaOH in step (two) is 1-1.1:3-3.1; As preferred, the heating reflux temperature in step (two) is 90-110 ℃; As preferred, the HCl concentration in step (two) is 5-7 M; As preferred, the washing in step (two) is performed by using deionized water; As preferred, the drying method in step (two) is vacuum drying, the temperature is 80 ℃, and the drying time is 8h.

[0009] The preparation method of the Mn-CP fluorescent probe material comprises the following steps: (One) stirring the manganese chloride and H3L ligand in acetonitrile and H2O to obtain a yellow transparent liquid; (Two) transferring the yellow transparent liquid in step (one) into a heat-resistant glass tube for sealing, then placing the heat-resistant glass tube in a constant-temperature reactor at high temperature, after the reaction is completed, cooling to room temperature to obtain a yellow rectangular crystal; (Three) after the obtained yellow rectangular crystal is sequentially subjected to solid-liquid separation, water washing and drying, the target product is obtained.

[0010] As preferred, the molar ratio of the H3L ligand to manganese chloride in step (one) is 1:2-2:3.

[0011] As preferred, the volume ratio of the acetonitrile to H2O in step (two) is 3:2.

[0012] As preferred, the constant-temperature reaction temperature in step (two) is 100-150 ℃, the time is 48-96 h, and the cooling rate is 3-6 ℃ / h.

[0013] As preferred, the Mn-CP material is washed with deionized water first, and then with acetonitrile in step (three).

[0014] The application further provides the application of the Mn-CP fluorescent probe material prepared according to the above preparation method as a fluorescent sensor in the detection of norfloxacin.

[0015] Specifically comprising the following steps: (One) grinding the Mn-CP fluorescent probe material, dispersing in deionized water to form a suspension liquid by ultrasonic, and measuring the fluorescence excitation, emission intensity and fluorescence recognition performance thereof; (ii) Preparation of the water solution of the antibiotic to be detected, and the prepared water solution of the antibiotic is added to the Mn-CP material suspension obtained in step (i) by using a pipette, and the fluorescence emission intensity is measured to obtain the relationship between the fluorescence response intensity of the Mn-CP and the concentration of norfloxacin, and the concentration of norfloxacin in the sample can be calculated by substituting the fluorescence intensity of the sample to be detected into the linear relationship (calibration curve).

[0016] Preferably, the Mn-CP material in step (i) is ground by a ball mill for 10-20 min to 60-80 mesh.

[0017] Preferably, the ultrasonic dispersion time in step (i) is 0.5-1.5 h, and the power is 50-70 Hz.

[0018] Preferably, the mass ratio of the Mn-CP material to water in the suspension of the Mn-CP material in step (i) is 1:600-700.

[0019] The Mn-CP fluorescent probe material provided by the application has good fluorescence intensity and stability, and can qualitatively and quantitatively detect norfloxacin in water. Compared with the existing detection method, it shows excellent sensitivity, selectivity, anti-interference and recyclability. The Mn-CP material is subjected to X-ray single crystal diffraction, thermogravimetric analysis and fluorescence analysis. BRIEF DESCRIPTION OF DRAWINGS Figure 1 Synthesis route of 5-(3-carboxy-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid (H3L); Figure 2 NMR H spectrum of the ligand 5-(3-carboxy-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid (H3L).

[0020] Figure 3 Five-core structure diagram of Mn-CP; Figure 4 Three-dimensional network diagram of Mn-CP; Figure 5 X-ray powder diffraction diagram of the Mn-CP fluorescent probe material; Figure 6 Thermogravimetric curve diagram of the Mn-CP fluorescent probe material; Figure 7 Fluorescence excitation and emission spectrum diagram of the Mn-CP fluorescent probe material; Figure 8Figure 4 is a fluorescence intensity comparison chart of the Mn-CP fluorescent probe material in the presence of different interfering antibiotics; wherein the light blue column shows the fluorescence response of the probe in the presence of various interferents (selectivity), and the dark blue column shows the fluorescence response after adding norfloxacin in the presence of these interferents (anti-interference); Figure 9 Figure 5 is a fluorescence response spectrum of the Mn-CP fluorescent probe material to different concentrations of norfloxacin; Figure 10 Figure 6 is a linear relationship chart of the fluorescence intensity ratio of the Mn-CP fluorescent probe material based on the S-V equation and the concentration of norfloxacin; Figure 11 Figure 7 is an X-ray photoelectron spectroscopy (XPS) chart of the Mn 3s orbital of the Mn-CP fluorescent probe material. DETAILED DESCRIPTION The present application will be further described below in conjunction with specific examples and drawings.

[0021] Synthesis of ligand 5-(3-carboxy-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid:

[0022] As shown in Figure 1 , after heating 2-hydroxy-4-oxo-4-(p-tolyl)-2-butenoic acid ethyl ester (3.5138 g, 15 mmol) with 5-hydrazinyl isophthalic acid (2.9424 g, 15 mmol) and 80 mL of anhydrous ethanol under reflux for 24-48 h, the brown solid powder was collected by filtration, washed and dried to obtain 5-(3-(ethoxycarbonyl)-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid. 5-(3-(ethoxycarbonyl)-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid (2.6691 g, 6.77 mmol), 30 mL of aqueous NaOH solution (2.5%) were heated under reflux for 1-2 h. After the solution was cooled, 5 M HCl solution was added dropwise thereto with constant stirring until solid precipitated, and then the solid was filtered and washed with deionized water and dried to obtain the organic ligand H3L with a yield of 96.70%. Figure 2 Figure 8 is a nuclear magnetic H spectrum of the ligand H3L, 1 H NMR (300 MHz, DMSO-d6): δ 8.49 (t, 1H, Ar-H), 7.97 (d, 2H, Ar-H), 7.18 (s, 4H, Ar-H), 7.01 (s, 1H, C3HN2-H), 2.29 (s,3H, CH3-H).

[0023] Example 1: Method of the Mn-CP fluorescent probe material, comprising the following steps: At room temperature, H3L (0.0092 g, 0.025 mmol) and MnCl2·4H2O (0.0099 g, 0.05 mmol) were dissolved in a mixed solvent of 6 mL acetonitrile and 4 mL H2O. The resulting mixture was then transferred to a heat-resistant glass tube and reacted at 120 °C for 72 h. The mixture was then cooled to room temperature at a rate of 3 °C / h, filtered, washed first with 4 mL of deionized water, and then washed with 4 mL of acetonitrile to obtain yellow cuboid crystals of Mn-CP. The yield was 46.1%. Example 2:

[0024] At room temperature, H3L (0.0110 g, 0.03 mmol) and MnCl2·4H2O (0.0119 g, 0.06 mmol) were dissolved in a mixed solvent of 3 mL acetonitrile and 2 mL H2O. The resulting mixture was then transferred to a heat-resistant glass tube and reacted at 100 °C for 96 h. The mixture was then cooled to room temperature at a rate of 4 °C / h, filtered, washed first with 6 mL of deionized water, and then washed with 6 mL of acetonitrile to obtain yellow cuboid crystals of Mn-CP. The yield was 55.4%. Example 3:

[0025] At room temperature, H3L (0.0147 g, 0.04 mmol) and MnCl2·4H2O (0.0119 g, 0.06 mmol) were dissolved in a mixed solvent of 6 mL acetonitrile and 4 mL H2O. The resulting mixture was then transferred to a heat-resistant glass tube and reacted at 110 °C for 60 h. The mixture was then cooled to room temperature at a rate of 3 °C / h, filtered, washed first with 7 mL of deionized water, and then washed with 7 mL of acetonitrile to obtain yellow cuboid crystals of Mn-CP. The yield was 51.7%.

[0026] Performance testing experiment 1. X-ray single-crystal diffraction analysis was performed on the Mn-CP fluorescent probe materials prepared in the above three embodiments of the present invention (the Mn-CP fluorescent probe materials obtained in Examples 1-3 are the same, i.e., the diffraction peak positions of the products in the three embodiments are confirmed to be consistent by X-ray powder diffraction testing, proving that they are the same crystalline phase material, only the yield is different). Figure 3 The molecular structure diagram confirms the structural integrity of the ligand molecule during coordination and demonstrates its multi-point coordination mode. In Mn-CP, five adjacent Mn atoms are linked by 18 carboxylic acid O atoms to form a ring, creating a pentanuclear secondary unit. These secondary units are then linked by (ClL). 4- Ligand ions are further linked to form a 3D framework structure (such as...) Figure 4 ).

[0027] 2. The phase purity of the Mn-CP fluorescent probe material prepared in Example 1 of the present invention was tested by powder diffraction at room temperature. For example... Figure 5 As shown, a large number of Mn-CP products exhibit good phase purity, which is basically consistent with their single-crystal simulated peaks. From Figure 11 It can be clearly seen from the graph that the corresponding Mn appears simultaneously. 2+ and Mn 3+ The signal peak indicates that manganese (Mn) undergoes a valence change, suggesting the presence of Mn in the sample. 2+ and Mn 3+ The mixed valence state.

[0028] 3. Thermogravimetric analysis was performed on the Mn-CP fluorescent probe material prepared in Example 1 of the present invention. Figure 6 It can be seen that as the temperature increases, the Mn-CP material loses 16.73% of its weight in the 40-121 ℃ range, according to the chemical formula [Mn5(ClL1)3(H2O)3]. n The calculation for 6n(CH3CN) is equivalent to the loss of 6 crystalline CH3CN molecules and 3 H2O water molecules, with a theoretical value of 16.99%. The weight remains essentially unchanged after 121 °C, but the remaining structure continues to decompose after 363 °C, with 38.35% of the weight remaining even at 800 °C. This indicates that the main framework structure of the Mn-CP material possesses good thermal stability.

[0029] 4. Perform fluorescence emission spectroscopy detection on the three-dimensional Mn-CP fluorescent probe material prepared in Example 1 of the present invention. For example... Figure 7 As shown, the three-dimensional Mn-CP fluorescent probe material prepared in Example 1 has a maximum emission wavelength of 415 nm when the excitation wavelength is 331 nm.

[0030] 5. A fluorescence detection experiment was performed on the Mn-CP fluorescent probe material prepared in Example 1 of the present invention. The specific steps are as follows: At room temperature, 30 mg of Mn-CP powder sample was placed in a ball mill and ground for 5 min, then dispersed in 30 mL of deionized H2O and sonicated for another 30 min to obtain a uniformly dispersed suspension (1 mg / mL). 1 mL of a 5 × 10⁻⁶ Mn-CP fluorescent probe material was then taken. -4 Antibiotic aqueous solutions of mol / L (norfloxacin (NOR), furazolidone (FZD), dopamine hydrochloride (PDA), chlortetracycline hydrochloride (CTC), metronidazole (MDZ), sulfadiazine (SDZ), and amoxicillin (AMX)) were added to 2 mL of the above-mentioned coordination polymer suspensions, sonicated for 30 s, and allowed to stand for 5 min. The fluorescence emission spectra of the resulting suspensions were then measured. Figure 8As shown in the light blue column chart, the fluorescence intensity of most molecules added to the coordination polymer changes slightly but can be ignored, while the addition of norfloxacin can enhance the fluorescence of Mn-CP, and the enhancement efficiency reaches 16 times, so the recognition of Mn-CP to norfloxacin shows excellent selectivity. Figure 9 As shown, with the increase of the concentration of norfloxacin solution, it is found that the emission intensity of the Mn-CP fluorescent probe material is continuously enhanced. Figure 10 As shown, the relative fluorescence intensity ratio ( I / I 0 )-1 and C NOR In a linear relationship of 0-0.015 mM, it indicates that it can quantitatively detect norfloxacin in water at low concentration, and the linear fitting gives K sv (NOR) = 7.73 × 10 5 M -1 , the correlation coefficient R 2 = 0.9987, and the formula LOD (detection limit) = 3 sigma / k The detection limit of Mn-CP for norfloxacin recognition is 1.86 nM (the emission spectrum of Mn-CP measured by ten blank cycles, and the normalized fluorescence intensity value of Mn-CP is respectively: 0.99990, 0.99929, 0.99876, 0.99943, 0.99999, 0.99923, 1, 0.99919, 0.99866, 0.99910. The standard deviation formula gives sigma = 0.000479).

[0031] 6、The Mn-CP fluorescent probe material prepared in the above embodiment 1 of the application is subjected to anti-interference experiment analysis. In the presence of other various antibiotic solutions, norfloxacin aqueous solution is added, and the fluorescence emission spectrum of the obtained suspension is tested. As shown in Figure 8 As shown in the dark blue column chart, in the presence of interfering antibiotic solutions, the recognition of Mn-CP fluorescent probe material to norfloxacin is almost not affected, which shows that the material has good anti-interference ability for the detection of norfloxacin in water.

[0032] In summary, the application designs and synthesizes a new type of Mn-CP fluorescent probe material for the detection of norfloxacin in water, which not only has fast detection speed, but also shows strong sensitivity, thermal stability and anti-interference, and the preparation method is simple, low in cost, small in pollution and easy to operate.

[0033] The above-mentioned examples are only preferred experimental schemes of the present application, and it should be pointed out that, for the operating personnel in the art, the experimental schemes have different expression ways, and can be appropriately polished and modified on the basis of the examples of the present application, but all are within the protection scope of the present application.

Claims

1. A Mn-CP fluorescent probe material, characterized in that: The chemical structural unit of the Mn-CP fluorescent probe material is: [Mn5(ClL)3(H2O)3], where (ClL) is the chemical unit. 4- The ligand 5-(3-carboxy-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid (H3L) is formed simultaneously during its coordination reaction with MnCl2·4H2O.

2. The Mn-CP fluorescent probe material according to claim 1, characterized in that: Mn-CP in Z = 6 hexagonal crystal system P 63 / m Crystallization in space group, unit cell parameters: a =20.4785(2) Å, b = 20.4785(2) Å, c = 11.16810(10) Å, α = 90°, β = 90°, γ = 120°.

3. The Mn-CP fluorescent probe material according to claim 1, characterized in that: The preparation method of the 5-(3-carboxy-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid (H3L) includes the following steps: (i) In an alcohol solvent, ethyl 2-hydroxy-4-oxo-4-(p-tolyl)-2-butenoate is subjected to a condensation cyclization reaction with 5-hydrazino-isophthalic acid to obtain the intermediate 5-(3-(ethoxycarbonyl)-5-(p-tolyl)-1H-pyrazol-1-yl)isophthalic acid; (ii) Under alkaline conditions, the intermediate described in step (i) is subjected to a hydrolysis reaction, followed by acidification to precipitate the organic ligand (H3L).

4. The Mn-CP fluorescent probe material according to claim 3, characterized in that: In step (i), the molar ratio of ethyl 2-hydroxy-4-oxo-4-(p-tolyl)-2-butenoate to 5-hydrazinophthalic acid is 1-1.1:1-1.1; and / or, the reflux heating time is 24-48 h.

5. The Mn-CP fluorescent probe material according to claim 3, characterized in that: In step (ii), the molar ratio of the intermediate to the base under alkaline conditions is 1:3-1.1:3.1; and / or the hydrolysis reaction temperature is 90-110 ℃.

6. A method for preparing the Mn-CP fluorescent probe material according to any one of claims 1-5, characterized in that, Includes the following steps: (a) A yellow transparent liquid obtained by dissolving manganese chloride and H3L ligand in a solvent system and stirring at room temperature; (ii) The mixture from step (a) is subjected to a solvothermal reaction under sealed conditions to generate crystals; (III) Separate and purify the crystal to obtain the Mn-CP fluorescent probe material.

7. The method according to claim 6, characterized in that: In step (a), the molar ratio of H3L ligand to manganese chloride is 1:2-2:3; the solvent system contains acetonitrile and water, and the volume ratio of acetonitrile to H2O is 3:

2.

8. The method according to claim 6, characterized in that: In step (ii), the isothermal reaction temperature is 100-150℃ and the time is 48-96 h.

9. The use of the Mn-CP fluorescent probe material according to any one of claims 1-5 in the preparation of a fluorescent probe for detecting norfloxacin.

10. The application according to claim 9, characterized in that: Includes the following steps: Step (a) Disperse the Mn-CP fluorescent probe material according to claim 1 or 2 in a liquid medium to form a suspension; Step (II) Prepare the antibiotic aqueous solution to be tested. Use a pipette to add the prepared antibiotic aqueous solution to the Mn-CP material suspension obtained in step (I). Measure its fluorescence emission intensity to obtain the relationship between the fluorescence response intensity of Mn-CP and the concentration of norfloxacin, which is used to test the concentration of norfloxacin in the sample.

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