Preparation method and application of MOFs fluorescent probe for detecting HSO4 <->

Abstract

The invention discloses a preparation method and application of an MOFs (Metal-Organic Frameworks) fluorescent probe for detecting HSO4 <->, relates to preparation and application of a coumarin functionalized MOFs fluorescent probe, and aims to solve the technical problem that the existing fluorescent probe for detecting HSO4 <-> is poor in specificity. The preparation method of the fluorescent probe comprises the following steps: adding ZIF-90 into a methanol solution containing 7-N, N '-diethylaminocoumarin-3-thiosemicarbazide imine, uniformly mixing, heating and refluxing under a stirring condition, and centrifuging, washing and drying the obtained product to obtain the 7-N, N'-diethylaminocoumarin-3-thiosemicarbazide fluorescent probe. A to-be-detected solution is added into a fluorescent probe solution, the concentration of HSO4 <-> is detected by changing fluorescence intensity before and after the to-be-detected solution is added, the linear range is 100-700 mu M, the detection limit is 0.51 mu M, and the response time is 360 s. The fluorescent test paper can also be prepared into portable fluorescent test paper, and HSO4 <-> can be detected according to color change under sunlight or an ultraviolet lamp after the fluorescent test paper is dripped into a solution to be detected. The method can be used in the field of HSO4-detection.

Description

Technical Field

[0001] The invention relates to the preparation and application of a coumarin functionalized MOFs fluorescent probe, and belongs to the technical field of fluorescent sensors. Technical Background

[0002] Anions play an important role in biology, pharmacology and environmental science. They are widely present in organisms, but excessive concentrations can have adverse effects on humans or animals. - As an environmental pollutant, it is widely found in fertilizers, industrial raw materials, and nuclear fuel waste. It has certain biological toxicity. High doses of HSO4 - It can cause diarrhea, irritation to the skin and eyes, and even respiratory paralysis. Therefore, an effective and reliable method is needed to detect HSO4 - It is very necessary.

[0003] Many reports have been published on the detection of HSO4 - There are many methods for the detection of analytes, such as atomic absorption spectroscopy and electrochemical analysis. However, the high cost of instruments, the need for professional personnel, and the complex procedures make these methods difficult to use for routine monitoring and application. Fluorescence analysis has the advantages of high sensitivity, short response time, easy operation, and low cost, and is very suitable for detecting low-concentration analytes.

[0004] Metal-organic frameworks (MOFs) are coordination polymers with well-defined pore structures and open metal sites. With unique properties such as structural diversity and modifiability, MOFs have been widely used in catalysis, gas storage, drug delivery, and sensing. To date, many MOFs with fluorescent properties have been developed for sensing of various analytes, including metal ions, anions, and organic small molecules. For example, Inorganica Chimica Acta reported a Zn-MOF multifunctional detection probe in 2023, issue 556, 121643, for HSO4 - Produces fluorescence quenching response, and the selectivity is not high; Journal of Molecular Structure (Journal of Molecular Structure) publicly reported a Cd-MOF multifunctional detection probe in 2024, issue 1299, 137132, for HSO4 - It produces fluorescence quenching response, and the selectivity is not high. At present, no Chinese patents have been found to report the use of MOFs materials for HSO4 - Fluorescence detection. Summary of the invention

[0005] The present invention aims to solve the existing problem of detecting HSO4 -The fluorescent probes have poor specificity, poor water resistance and poor naked eye detection effect, and provide a method for detecting HSO4 - The preparation method and application of MOFs fluorescent probe is an efficient and reliable fluorescent probe that can be used to detect HSO4 in actual water samples. - , and it can be made into a portable fluorescent test paper.

[0006] The present invention detects HSO4 - The preparation method of the MOFs fluorescent probe is carried out according to the following steps:

[0007] 1. Preparation of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide imine (DCMH): 7-diethylaminocoumarin-3-formaldehyde and 1,3-diaminothiourea were dissolved in anhydrous ethanol in a three-necked flask, the pH value of the system was adjusted to 4-4.5 with acetic acid, and then refluxed for 4-5 hours under nitrogen protection, cooled to room temperature, and the suspension was filtered with a microporous filter membrane; the filter cake was washed with distilled water and hot ethanol in turn, and then vacuum dried to obtain 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide imine (DCMH);

[0008] 2. Preparation of ZIF-90: Dissolve Zn(NO3)2·6H2O in methanol, then add triethylamine under stirring to obtain zinc nitrate solution; then dissolve imidazole-2-carboxaldehyde in methanol to obtain imidazole-2-carboxaldehyde solution; drop imidazole-2-carboxaldehyde solution into zinc nitrate solution, stir at room temperature for 20 to 30 minutes to obtain suspension; centrifuge the suspension to obtain precipitate, wash the precipitate with methanol, and then vacuum dry to obtain ZIF-90, which is a light yellow powder;

[0009] 3. Preparation of ZIF-90@Coumarin: 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide and ZIF-90 were dispersed in methanol and heated to boiling and kept under reflux for 6 h; the suspension was cooled to room temperature, filtered with a 0.22 μm microporous filter membrane, washed with methanol and hot ethanol, and vacuum dried to obtain the detection HSO4 - The MOFs fluorescent probe is a dark brown powder, denoted as ZIF-90@Coumarin.

[0010] Preferably, the molar ratio of 7-diethylaminocoumarin-3-carboxaldehyde to 1,3-diaminothiourea in step 1 is 1:(2-2.2).

[0011] Preferably, the ratio of the mass of diethylaminocoumarin-3-carboxaldehyde to the volume of anhydrous ethanol in step 1 is (10-15) mg: 1 mL;

[0012] Preferably, the mass fraction of acetic acid in step 1 is 20%.

[0013] Preferably, the drying in step 1 is vacuum drying at a temperature of 60° C. for 5 hours.

[0014] Preferably, the concentration of Zn(NO3)2·6H2O in the zinc nitrate solution in step 2 is 14-16 g / L.

[0015] Preferably, the mass ratio of Zn(NO3)2·6H2O to triethylamine in step 2 is 1:(8-9).

[0016] Preferably, the concentration of imidazole-2-carboxaldehyde in the imidazole-2-carboxaldehyde solution in step 2 is 0.1 to 0.12 mol / L.

[0017] Preferably, in step 2, the molar ratio of Zn(NO3) in the Zn(NO3) solution to imidazole-2-carboxaldehyde in the imidazole-2-carboxaldehyde solution is 1:(2-2.2);

[0018] Preferably, the centrifugation in step 2 is performed at a rotation speed of 6000 rpm / min for 5 minutes.

[0019] Preferably, the vacuum drying in step 2 is performed at 80° C. for 6 h.

[0020] Preferably, the mass ratio of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide to ZIF-90 in step three is 1:(1.6-1.9).

[0021] Preferably, the ratio of the mass of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide imine to the volume of methanol in step 3 is (2.5-3.0) mg:1 mL.

[0022] Preferably, the vacuum drying in step 3 is vacuum drying at a temperature of 80° C. for 8 hours.

[0023] The detection HSO4 prepared by the above method - The application of MOFs fluorescent probe is to detect HSO4 - MOFs materials fluorescent probe for HSO4 in aqueous solution - Detection.

[0024] Using HSO4 detection - MOFs fluorescent probe for detecting HSO4 in aqueous solution - The method is as follows:

[0025] The volume ratio of methanol to H2O was 99:1, and the HSO4- The MOFs material fluorescent probe is dissolved in a methanol aqueous solution at a concentration of 30 mg / L to obtain a probe solution; the aqueous solution to be tested is added to the probe solution, mixed evenly, to obtain a solution to be tested; the fluorescence spectra of the probe solution and the solution to be tested are tested, and the fluorescence intensity of the probe solution at 521 nm is A; the fluorescence intensity of the solution to be tested at 521 nm is B. If B = (12-70) A, then the aqueous solution to be tested contains HSO4 - .

[0026] Using HSO4 detection - The method for preparing a portable fluorescent test paper using a MOFs material fluorescent probe is as follows: soak the filter paper in a methanol dispersion of ZIF-90@Coumarin (100 mg / L) for 1.5 to 2 hours. Then, the filter paper is dried at room temperature to obtain a portable test paper.

[0027] Drop the test solution onto the portable fluorescent test paper. If the fluorescent test paper does not change color under sunlight and ultraviolet light, the test solution does not contain HSO4. - If the test paper is orange under sunlight or yellow-green under ultraviolet light, the aqueous solution to be tested contains HSO4 - .

[0028] The present invention first uses 7-diethylaminocoumarin-3-formaldehyde and 1,3-diaminothiourea to prepare 7-N,N′-diethylaminocoumarin-3-semicarbazide imine (DCMH); then DCMH is reacted with ZIF-90 to synthesize and detect HSO4 - MOFs fluorescent probe ZIF-90@Coumarin, the synthetic route of the probe and its reaction with HSO4 - The fluorescence recognition diagram is as follows Figure 1 As shown. This fluorescent probe can detect 8 anions (F - , Cl - ,Br - , I - , HSO4 - , H2PO4 - ,AcO - , CN - ) to specifically identify HSO4 - In the range of 100~700mmol / L, the fluorescence intensity (F) of ZIF-90@Coumarin and HSO4 - The concentration (c) showed a good linear relationship, and the detection limit was 0.51 μmol / L.

[0029] The fluorescent probe ZIF-90@Coumarin of the present invention can specifically recognize HSO4 -, which has the characteristics of short detection time and high sensitivity, and can be made into portable test paper to detect HSO4 in samples - The materials required by the present invention are cheap and easy to obtain, the preparation method is simple, the product has a regular morphology, and has strong practicality, and can be used as a detection method for HSO4 - The fluorescent probe has potential application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The detection HSO4 prepared by the present invention - Synthesis route of the coumarin-functionalized MOFs fluorescent probe ZIF-90@Coumarin and its effect on HSO4 - Fluorescence identification map of

[0031] Figure 2 The SEM images of ZIF-90 prepared in step 2 of Example 1 and ZIF-90@Coumarin prepared in step 3 are shown;

[0032] Figure 3 XRD spectra of ZIF-90 prepared in step 2 of Example 1 and ZIF-90@Coumarin prepared in step 3;

[0033] Figure 4 The Fourier transform infrared spectra of DCMH prepared in step 1, ZIF-90 prepared in step 2, and ZIF-90@Coumarin prepared in step 3 in Example 1;

[0034] Figure 5 The XPS spectra of ZIF-90 and ZIF-90@Coumarin prepared in Example 1; (a) is the full spectrum of ZIF-90 and ZIF-90@Coumarin; (b) is the N1s spectrum of ZIF-90; (c) is the N1s spectrum of ZIF-90@Coumarin; (d) is the S2p spectrum of ZIF-90@Coumarin;

[0035] Figure 6 Different concentrations of HSO4 in methanol / H2O (V / V = 99:1) - Fluorescence spectra of ZIF-90@Coumarin in the presence of;

[0036] Figure 7 The fluorescence intensity (F) of ZIF-90@Coumarin in methanol / H2O (V / V = 99:1) and HSO4 - Concentration (c) relationship curve

[0037] Figure 8The ZIF-90@Coumarin in methanol / H2O (V / V = 99:1) reacts with HSO4 - Selection and competition experiments, black bars represent the absence of HSO4 - Fluorescence response of ZIF-90@Coumarin (30 mg / L) to anions (1400 μmol / L), the white bar represents the presence of HSO4 - The fluorescence response of ZIF-90@Coumarin to anions (λ ex =370nm);

[0038] Fig. 9 The photos of ZIF-90@Coumarin in methanol (methanol / H2O; V / V=99:1) with different anions added under sunlight and 365 nm ultraviolet light;

[0039] Fig.10 The reaction of ZIF-90@Coumarin with HSO4 in methanol (methanol / H2O; V / V = 99:1) - Time response of

[0040] Fig.11 For ZIF-90@Coumarin test paper containing HSO4 - Photos of the solution painted under sunlight and 365nm UV light. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with embodiments and drawings.

[0042] Example 1: A method for detecting HSO4 in this example - The preparation method of the MOFs fluorescent probe is carried out according to the following steps:

[0043] 1. Preparation of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide (DCMH): 245 mg of 7-diethylaminocoumarin-3-formaldehyde and 212 mg of 1,3-diaminothiourea were dissolved in 20 mL of anhydrous ethanol in a 100 mL three-necked flask, and the pH of the system was adjusted to 4 with acetic acid having a mass percentage concentration of 20%, and then refluxed for 4 h under nitrogen protection, cooled to room temperature, and the suspension was filtered with a 0.22 μm microporous filter membrane; the filter cake was washed with distilled water and hot ethanol at a temperature of 70°C for 3 times each, and vacuum dried at 60°C for 5 h to obtain 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide;

[0044] 2. Preparation of ZIF-90: 1.47 g Zn(NO3)2·6H2O was dissolved in 100 mL methanol, and then 12.14 g triethylamine was added under stirring, and finally 100 mL of 0.1 mol / L imidazole-2-carboxaldehyde methanol solution was slowly added dropwise, and stirred at room temperature for 30 minutes; the suspension was centrifuged at a speed of 6000 rpm / min for 5 minutes, and the supernatant was discarded to obtain a nitrogen yellow precipitate, which was washed with methanol 3 times, and then vacuum dried at 80°C for 6 hours to obtain a light yellow powder ZIF-90;

[0045] 3. Preparation of ZIF-90@Coumarin: 334 mg of DCMH obtained in step 1 and 600 mg of ZIF-90 obtained in step 2 were dispersed in 125 mL of methanol and refluxed for 6 h; the suspension was cooled to room temperature, filtered with a 0.22 μm microporous filter membrane, washed with methanol and 50 ° C ethanol, and vacuum dried at 80 ° C for 8 h to obtain the detection HSO4 - The MOFs material fluorescent probe is a dark brown powder, denoted as ZIF-90@Coumarin.

[0046] The SEM images of ZIF-90 prepared in step 2 and ZIF-90@Coumarin prepared in step 3 are shown in FIG. Figure 2 As shown, (a) and (b) are scanning electron micrographs of ZIF-90, (c) and (d) are scanning electron micrographs of ZIF-90@Coumarin. Figure 2 As can be seen from (a) and (b), ZIF-90 synthesized at room temperature presents a relatively complete rhombic dodecahedron configuration, proving that ZIF-90 with high crystallinity was successfully synthesized. Figure 2 From (c) and (d), we can see that after covalent modification with DCMH, the morphology of ZIF-90@Coumarin presents a unique octahedral configuration, which is significantly different from ZIF-90.

[0047] Figure 3 The X-ray powder diffraction (PXRD) spectra of ZIF-90 prepared in step 2 and ZIF-90@Coumarin prepared in step 3. Figure 3It can be seen that ZIF-90 has relatively sharp diffraction peaks corresponding to (011), (200), (112), (022), (013) and (222) crystal planes at 7.24°, 10.24°, 12.54°, 14.48°, 16.22° and 17.78°, respectively, which proves that ZIF-90 has been successfully synthesized. ZIF-90@Coumarin has many new diffraction peaks different from ZIF-90 in the range of 5 to 25°, indicating that its crystal structure has changed after the DCMH compound is covalently linked to ZIF-90.

[0048] Figure 4 FT-IR spectra of DCMH prepared in step 1, ZIF-90 prepared in step 2, and ZIF-90@Coumarin prepared in step 3. Figure 4 It can be seen that ZIF-90 has a peak at 2850 cm -1 and 1677cm -1 The CH stretching vibration peak and C=O stretching vibration peak of the 2-position aldehyde group of the imidazole ligand appeared at 3270cm -1 and 3162cm -1 The characteristic peaks of symmetric and asymmetric stretching vibrations of NH in -NH2 appeared at 1253 cm -1 The characteristic peak of stretching vibration attributed to C=S appeared at 1667cm -1 The C=O stretching vibration peak attributable to the aldehyde group was significantly weakened, and C=S (1265cm -1 ) peak, and at 3300~3500cm -1 The characteristic peaks belonging to -NH2 did not appear in the range of . The above results proved that DCMH was successfully grafted onto ZIF-90 through Schiff base reaction.

[0049] Figure 5 The XPS spectra of ZIF-90 and ZIF-90@Coumarin are shown in Figure 1, where (a) is the full spectrum of ZIF-90 and ZIF-90@Coumarin, (b) is the N1s spectrum of ZIF-90, (c) is the N1s spectrum of ZIF-90@Coumarin, and (d) is the S2p spectrum of ZIF-90@Coumarin. Figure 5 As shown in (a), both ZIF-90 and ZIF-90@Coumarin show characteristic peaks representing Zn 2p, O1s, N1s and C1s. In addition, ZIF-90@Coumarin also shows a characteristic peak representing S2p at around 162.00 eV. Figure 5(b) is the N1s spectrum of ZIF-90. ZIF-90 has characteristic peaks at 398.74 and 399.28 eV, which are attributed to CN and C=N in the imidazole ligand, respectively. Figure 5 (c) is the N1s spectrum of ZIF-90@Coumarin. Compared with ZIF-90, ZIF-90@Coumarin has characteristic peaks at 399.04 eV and NH4+. Figure 5 (d) is the S2p spectrum of ZIF-90@Coumarin. ZIF-90@Coumarin has S2p ​​peaks at 161.69 eV and 162.85 eV. 3 / 2 and S2p 1 / 2 The above characterization results further prove that the compound DCMH is covalently linked to ZIF-90 through Schiff base reaction.

[0050] The ZIF-90@Coumarin fluorescent probe prepared in Example 1 was used to detect HSO4 - For quantitative analysis, a methanol-water solution with a volume ratio of methanol to H2O of 99:1 was used as solvent, and ZIF-90@Coumarin was added to the methanol-water solution at a concentration of 30 mg / L to obtain a suspension; HSO4 was then gradually added to the suspension. - , test different HSO4 - Fluorescence spectra at concentrations such as Figure 6 As shown, from Figure 6 It can be seen that with the increase of HSO4 - With the increase of the concentration of (0~1900μmol / L), the fluorescence intensity of ZIF-90@Coumarin suspension increases continuously, and the wavelength obviously red shifts. - When the concentration reached 1400 μmol / L, the fluorescence intensity of the system reached the maximum, increasing by 67.4 times, and the wavelength red-shifted by 54 nm; - The fluorescence intensity of the system does not change. - The relationship curve of concentration (c) is as follows Figure 7 As shown, in methanol-water solution, HSO4 - When the concentration of ZIF-90@Coumarin is in the range of 100-700 μmol / L, the fluorescence intensity (F) of ZIF-90@Coumarin is related to HSO4 - The concentration (c) shows a good linear relationship, and its linear fitting equation is Y = 1.21858X-128.40286, R 2=0.98306. According to LOD = 3σ / k (σ is the deviation of 20 standard blank samples, k is the slope of the linear fitting curve), ZIF-90@Coumarin has a good affinity for HSO4 - The limit of detection (LOD) was 0.51 μmol / L.

[0051] The response performance of the ZIF-90@Coumarin fluorescent probe prepared in Example 1 to different anions was tested. A methanol aqueous solution with a volume ratio of methanol to H2O of 99:1 was used as a solvent, and ZIF-90@Coumarin was added to the methanol aqueous solution at a concentration of 30 mg / L to obtain a suspension; 3 μL of anions with a concentration of 0.1 mol / L were then added to 3 mL of the suspension, wherein the anions were F - , Cl - Br - ,I - 、HSO4 - 、HPO4 - ,AcO - , CN - , scan the respective spectra using a fluorescence spectrophotometer; then add 3 μL of 0.1 mol / L HSO4 - , and scan the respective spectra again in the fluorescence spectrophotometer. The obtained fluorescence titration spectrum is as follows Figure 8 As shown, from Figure 8 It can be seen that when HSO4 - When coexisting with other anions, although other anions recognize HSO4 - There is a certain degree of interference, but the system still produces obvious fluorescence enhancement. Other anions have no significant effect on HSO4 - In summary, ZIF-90@Coumarin has a good effect on HSO4 - The detection has good anti-interference ability.

[0052] Investigation of the fluorescence probe ZIF-90@Coumarin for HSO4 - In a methanol-water solution with a methanol / H2O volume ratio of 99:1, ZIF-90@Coumarin was added at a concentration of 30 mg / L, and then different anions were added at a concentration of 30 mg / L. The color changes under sunlight and ultraviolet light are shown in the following figure. Fig. 9 As shown in the figure, adding HSO4 - The ZIF-90@Coumarin dispersion changes from light pink to yellow under sunlight and exhibits strong green fluorescence under ultraviolet light.- , Cl - Br - ,I - 、HSO4 - 、H2PO4 - ,AcO - , CN - The above results show that the ZIF-90@Coumarin probe has no obvious color change in methanol / H2O (V / V = 99:1) for HSO4 - It has strong naked eye recognition capability.

[0053] Test Example 1 prepared ZIF-90@Coumarin fluorescent probe HSO4 - The time response, Fig.10 In a methanol-water solution with a volume ratio of methanol to H2O of 99:1, the ZIF-90@Coumarin probe showed good sensitivity to HSO4 - As can be seen from the figure, when 30 μL of HSO4 is added to methanol / H2O (V / V = 99:1), - After that, the fluorescence intensity of the system reached the maximum at 360s, and then the fluorescence intensity remained stable. The above results show that the ZIF-90@Coumarin probe can sensitively detect HSO4 in a short time. - .

[0054] The ZIF-90@Coumarin fluorescent probe prepared in Example 1 was used to detect HSO4 in water samples. - The water from Laodong Lake in Qiqihar and tap water were used as real water samples, and the HSO4 in the two water samples was determined by the standard addition method. - The specific steps are as follows:

[0055] Tap water (500 mL) was taken from the tap water network system of Qiqihar City, and lake water (500 mL) was taken from Laodong Lake in Qiqihar. All tested water samples were filtered through a 0.22 μm microporous filter membrane. The content of the analyte in the solution was determined using 20 sample solutions. Different amounts of the analyte were added to the sample, and the fluorescence signal of each sample was recorded. Each test was repeated 3 times.

[0056] From the data in Table 1, it can be seen that HSO4 - The recovery rate is high, ranging from 99.42% to 101.13%, and the relative standard deviation (RSD) is small, less than 4.32%. The above experimental results show that ZIF-90@Coumarin can be used for HSO4 in actual water samples. - detection and can exclude the influence of potential interferents.

[0057] Table 1 Detection of HSO4 by ZIF-90@Coumarin in real water samples - The recovery and standard deviation

[0058]

[0059] The ZIF-90@Coumarin prepared in Example 1 was used to prepare a portable fluorescent test paper, and the HSO4 - Qualitative detection, the specific operation steps are as follows: take methanol-water solution with a volume ratio of methanol to H2O of 99:1 as solvent, add ZIF-90@Coumarin to the methanol-water solution at a concentration of 100 mg / L to obtain a methanol dispersion of ZIF-90@Coumarin; then soak the filter paper in the methanol dispersion of ZIF-90@Coumarin for 1 hour, then take out the filter paper and dry it at room temperature to obtain a portable fluorescent test paper. Dip a glass rod in 0.1 mol / L HSO4 - Write "HSO4 - ", and place the test paper under sunlight and ultraviolet light for observation. The photos obtained are as follows Fig.11 As shown, from Fig.11 It can be seen that under sunlight, HSO4 is written on the test paper. - The part of the test paper is orange. Under 365nm ultraviolet light, the same area shows obvious yellow-green fluorescence. In contrast, the test paper does not contain HSO4 - The solution did not change under sunlight or UV light. The above results prove that the ZIF-90@Coumarin probe can be made into a portable test paper for qualitative detection of HSO4 in samples. - .

Claims

1. A method for detecting HSO4 - A method for preparing a MOFs fluorescent probe, characterized in that: The method proceeds as follows:

1. Preparation of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide: 7-diethylaminocoumarin-3-formaldehyde and 1,3-diaminothiourea were dissolved in anhydrous ethanol in a three-necked flask, the pH value of the system was adjusted to 4-4.5 with acetic acid, and then refluxed for 4-5 hours under nitrogen protection, cooled to room temperature, and the suspension was filtered with a microporous filter membrane; the filter cake was washed with distilled water and hot ethanol in turn, and then vacuum dried to obtain 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide; 2. Preparation of ZIF-90: Dissolve Zn(NO3)2·6H2O in methanol, then add triethylamine under stirring to obtain zinc nitrate solution; then dissolve imidazole-2-carboxaldehyde in methanol to obtain imidazole-2-carboxaldehyde solution; drop imidazole-2-carboxaldehyde solution into zinc nitrate solution, stir at room temperature for 20 to 30 minutes to obtain suspension; centrifuge the suspension to obtain precipitate, wash the precipitate with methanol, and then vacuum dry to obtain ZIF-90, which is a light yellow powder; 3. Preparation of ZIF-90@Coumarin: 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide and ZIF-90 were dispersed in methanol and heated to boiling and kept under reflux for 6 h; the suspension was cooled to room temperature, filtered with a 0.22 μm microporous filter membrane, washed with methanol and hot ethanol, and vacuum dried to obtain the detection HSO4 - MOFs material fluorescent probe.

2. A method for detecting HSO4 according to claim 1. - A method for preparing a MOFs fluorescent probe, characterized in that: The molar ratio of 7-diethylaminocoumarin-3-carboxaldehyde to 1,3-diaminothiourea described in step 1 is 1:(2.0-2.2).

3. A method for detecting HSO4 according to claim 1 or 2. - A method for preparing a MOFs fluorescent probe, characterized in that: The concentration of Zn(NO3)2·6H2O in the zinc nitrate solution described in step 2 is 14-16 g / L.

4. A method for detecting HSO4 according to claim 1 or 2. - A method for preparing a MOFs fluorescent probe, characterized in that: The mass ratio of Zn(NO3)2·6H2O to triethylamine described in step 2 is 1:(8-9).

5. A method for detecting HSO4 according to claim 1 or 2. - A method for preparing a MOFs fluorescent probe, characterized in that: In step 2, the molar ratio of Zn(NO3)2 in the Zn(NO3)2 solution to imidazole-2-carboxaldehyde in the imidazole-2-carboxaldehyde solution is 1:(2.0-2.2).

6. A method for detecting HSO4 according to claim 1 or 2. - A method for preparing a MOFs fluorescent probe, characterized in that: The mass ratio of 7-N,N′-diethylaminocoumarin-3-thiosemicarbazide to ZIF-90 described in step 3 is 1:(1.6-1.9).

7. A method for detecting HSO4 prepared by the method of claim 1 - The application of MOFs fluorescent probe is characterized in that This application is to detect HSO4 - MOFs material fluorescent probe for HSO4 in aqueous system - Detection.

8. A method for detecting HSO4 prepared by the method of claim 1 according to claim 7. - The application of MOFs fluorescent probe is characterized in that Using HSO4 detection - MOFs material fluorescent probe for detecting HSO4 in aqueous system - The method is as follows: The volume ratio of methanol to H2O was 99:1, and the HSO4 - The MOFs fluorescent probe is dissolved in a methanol aqueous solution at a concentration of 30 mg / L to obtain a probe solution; the aqueous solution to be tested is added to the probe solution, and the mixture is mixed evenly to obtain a solution to be tested; the fluorescence spectra of the probe solution and the solution to be tested are tested, and the fluorescence intensity of the probe solution at 521 nm is A; The fluorescence intensity of the solution to be tested at 521nm is B. If B = (12-70)A, then the aqueous solution to be tested contains HSO4 - .

9. A method for detecting HSO4 prepared by the method of claim 1 - A method for preparing a portable fluorescent test paper using a MOFs fluorescent probe, characterized in that: The method is specifically as follows: soak the filter paper in a methanol dispersion of ZIF-90@Coumarin with a concentration of 100 mg / L for 1.5 to 2 hours, and then dry the filter paper at room temperature to obtain a portable test paper.

10. Detection of HSO4 in aqueous solution using the portable fluorescent test paper prepared by the method of claim 9 - The method is characterized in that The method is: drop the aqueous solution to be tested onto a portable fluorescent test paper. If the fluorescent test paper does not change color under sunlight and ultraviolet light, the aqueous solution to be tested does not contain HSO4. - If the test paper is orange under sunlight or yellow-green under ultraviolet light, the aqueous solution to be tested contains HSO4 - .

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