A method for identifying heavy metal Ba 2+ Functionalized covalent organic framework fluorescent probe and its application

Abstract

A functionalized covalent organic framework fluorescent probe for identifying heavy metal Ba2+ and its application, wherein the structural formula is as follows: #imgabs0# wherein R2 is #imgabs1# The functionalized covalent organic framework fluorescent probe is effective in identifying heavy metal Ba 2+ The solvent system is acetonitrile and water in a volume ratio of 5:5. In the test water sample, a fluorescent probe is added, and its fluorescence emission intensity is measured at an excitation wavelength of λ=366nm. The fluorescence intensity at 490nm is significantly enhanced. The test water sample contains heavy metal Ba 2+ The functionalized covalent organic framework probe is Ba 2+ The detection limit was 1.67×10 ‑8 mol / L. The advantage is that the probe can be used in MeCN:H 2 Highly selective fluorescence “off-on” identification of heavy metal Ba in O system 2+ , has a good linear range, low detection limit and good sensitivity, and has been successfully used in the detection of heavy metal Ba in real life 2+ .

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy metal identification, and particularly relates to a method for identifying heavy metal Ba 2+ Functionalized covalent organic framework fluorescent probes and their applications. Background Art

[0002] Barium is a slightly shiny silvery-white alkaline earth metal that exists in nature in the form of ore. Metallic barium and insoluble barium salts are non-toxic, but barium compounds that are soluble in water or dilute hydrochloric acid are toxic, and the severity depends on the dose of barium. At low doses, barium can act as a muscle stimulant, while at high doses, barium ions will be absorbed into the blood, bind to proteins and enzymes, affect the nervous system in the human body, and cause arrhythmia, tremors, weakness, anxiety, difficulty breathing, and paralysis.

[0003] Currently, selective detection of Ba 2+ This has been rarely addressed, and many fluorescent sensors are inherently non-selective, often limited by Mg from the same alkaline earth family. 2+ and Ca 2+ In addition, porous materials are often used as detection materials, such as quantum dots (CdTe and CdS), nanoparticles (TiO 2 and Cu-Au) and porous silica. Most of these materials are synthesized using metal precursors such as zinc, cadmium, titanium, copper, silver and gold, and these precursors are non-renewable and some are toxic.

[0004] Therefore, research is needed to develop highly selective and sensitive fluorescent probes to monitor heavy metal ions Ba. 2+ It is very necessary for people's healthy life. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for identifying heavy metal Ba with good specificity, high sensitivity, low detection limit and environmental friendliness. 2+ Functionalized covalent organic framework fluorescent probes and their applications.

[0006] The technical solution of the present invention is:

[0007] A method for identifying heavy metal Ba 2+ The functionalized covalent organic framework fluorescent probe has the following structural formula:

[0008]

[0009] Where R2 is

[0010] The fluorescent probe TpPa-COOH COF-HBT can be used to detect Ba2+ The specific recognition of. The synthetic route is as follows:

[0011] Furthermore, the specific synthesis process of the covalent organic framework fluorescent probe is as follows:

[0012] (1) Compound A (TpPa-COOH COF) was added with water to prepare a COF suspension, and 1-ethyl-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) were added to react at room temperature for 4 hours to obtain compound B 2 mol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide was added to every 100 g of compound A for reaction;

[0013] The molar ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 1:1.5;

[0014] (2) Take 0.25 g of the obtained compound C Add ethanol to dissolve, add to the compound B prepared in step (1), react at room temperature for 24 hours, the mass ratio of the compound C to the compound A is 5:1; then centrifuge, retain the solid, and wash with dichloromethane until the solvent is colorless to obtain the grafted compound D (TpPa-COOH COF-HBT) Where R2 is

[0015] Furthermore, the mass volume ratio of the compound C to ethanol is 0.01 g / mL.

[0016] Furthermore, the concentration of the COF suspension is 5 mg / mL.

[0017] A functionalized covalent organic framework fluorescent probe is used to identify heavy metal Ba 2+ Application in.

[0018] A functionalized covalent organic framework fluorescent probe is used to identify heavy metal Ba 2+ The application of the invention is special in that the fluorescent probe compound D can selectively identify the heavy metal Ba 2+ The solvent system is acetonitrile and water in a volume ratio of 5:5.

[0019] A functionalized covalent organic framework fluorescent probe is used to identify heavy metal Ba 2+The application of the method is special in that: in the water sample to be tested, the fluorescent probe L compound D is added, and its fluorescence emission intensity is measured at an excitation wavelength of λ = 366nm. The fluorescence intensity at 490nm is significantly enhanced. The water sample to be tested contains heavy metal Ba 2+ .

[0020] A functionalized covalent organic framework fluorescent probe is used to identify heavy metal Ba 2+ The application of the functionalized covalent organic framework probe to Ba 2+ The detection limit was 1.67×10 -8 mol / L.

[0021] Beneficial effects of the present invention:

[0022] The fluorescent probe TpPa-COOH COF-HBT synthesized by the present invention has a network structure of a covalent organic framework polymer TpPa-COOH COF that provides a large attachment surface. The aggregation of recognition groups can improve its detection sensitivity and reduce the detection limit. In addition, there is no structural collapse during the detection process. After the detection is completed, the probe can be removed by centrifugation, reducing the environmental pollution caused by the probe itself. The probe can be used in MeCN:H 2 Highly selective fluorescence “off-on” recognition of heavy metal Ba in O system 2+ , has a good linear range, low detection limit and good sensitivity, and has been successfully used in the detection of heavy metal Ba in real life 2+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a comparison chart of infrared spectra of the fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention and the used TpPa-COOHCOF;

[0024] Figure 2 The fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention was prepared in MeCN / H 2 Fluorescence spectra of O (5 / 5, v / v) after adding different metal ions (λ ex =366nm);

[0025] Figure 3 The colorimetric (a) graph and the fluorescence change (b) graph of the fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention in the presence of various metal ions;

[0026] Figure 4 The fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention was prepared in MeCN / H 2O (5 / 5, v / v) solution, and then Ba 2+ Fluorescence intensity change diagram when

[0027] Figure 5 The MeCN / H of the fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention 2 O (5 / 5, v / v) solution was added with different concentrations of Ba 2+ (0~1μM) after the probe fluorescence intensity change diagram (λ ex =366nm);

[0028] Figure 6 The fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention was prepared in MeCN / H 2 The emission intensity in O(5 / 5, v / v) solution is related to Ba 2+ Calibration curve plot of concentration;

[0029] Figure 7 The fluorescent probe TpPa-COOH COF-HBT and the probe TpPa-COOH COF-HBT+Ba synthesized in Example 1 of the present invention are 2+ Fluorescence intensity changes at different pH values ​​(λ ex =366nm);

[0030] Figure 8 The fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention was prepared in MeCN / H 2 O (5 / 5, v / v) solution for Ba 2+ Time response diagram of

[0031] Fig. 9 The fluorescence intensity of the fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention in three actual water samples is compared with that of Ba 2+ Linear relationship graph of concentration;

[0032] Fig.10 The fluorescent probe TpPa-COOH COF-HBT synthesized in Example 1 of the present invention was prepared in MeCN / H 2 BaO (5 / 5, v / v) solution measured in tap water, lake water and river water 2+ Concentration diagram. DETAILED DESCRIPTION

[0033] Example 1

[0034] (1) Compound A (TpPa-COOH COF) was prepared into a 5 mg / mL COF suspension. 1 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and 1.5 mmol of N-hydroxysuccinimide (NHS) were added to 10 mL of the 5 mg / mL COF suspension and reacted at room temperature for 4 hours to activate the carboxyl groups on TpPa-COOH COF to obtain compound B.

[0035] (2) Take 0.25 g of the obtained compound C Dissolve it with 25 mL of ethanol, mix the solution with the compound B synthesized in step (1), and react at room temperature for 24 hours. After the reaction, centrifuge to obtain a solid, and wash it with dichloromethane to remove the unreacted reactants. When the solvent is colorless, centrifuge to remove the solvent to obtain the grafted compound D (TpPa-COOH COF-HBT) Where R2 is

[0036]

[0037] 1. Characterization of the probe TpPa-COOH COF-HBT

[0038] TpPa-COOH COF and TpPa-COOH COF-HBT were characterized by Fourier transform infrared spectroscopy, as shown in Figure 1 As shown in the figure, compared with TpPa-COOH COF, TpPa-COOH COF-HBT has a higher peak at 1503 cm-1 on the basis of –C=C– and –C–N– bonds. -1 and 3459cm -1 Two new stretching vibration peaks appeared at 1503 cm -1 The stretching vibration peak at 3459cm is due to the stretching vibration of C=N on the compound C grafted with TpPa-COOH COF, -1 The stretching vibration peak at is caused by the stretching vibration of OH on compound C grafted with TpPa-COOHCOF, indicating that compound C was successfully grafted onto TpPa-COOH COF.

[0039] 2. Spectral determination of probe TpPa-COOH COF-HBT

[0040] (1) Preparation of various cationic solutions

[0041] Double distilled water was used throughout the preparation process, and the metal ions, including Al, were prepared using the corresponding nitrates or chlorides. 3+ ,Ag + Mg 2+ ,Cu2+ ,Pb 2+ ,Co 2+ ,Fe 2+ ,Fe 3+ ,Pd 2+ ,Ba 2+ ,Na + ,Hg 2+ ,Cr 3+ ,K + ,Ca 2+ ,Cd 2+ ,Ni 2 + ,Mn 2+ and Zn 2+ , to Ba 2+ For example, accurately weigh 85.68 mg of solid barium hydroxide and distill it into a 10 mL volumetric flask to make a 50 mM Ba 2+ The solution was tested;

[0042] (2) Preparation of probe TpPa-COOH COF-HBT solution

[0043] Accurately weigh 50 mg of TpPa-COOH COF-HBT compound and use 5 mL of MeCN / H 2 O (5 / 5, v / v) dispersion, and crushed with an ultrasonic cell crusher for 1 hour to make TpPa-COOH COF-HBT uniformly dispersed in water, that is, a 10 mg / mL probe suspension used for testing fluorescence performance was obtained;

[0044] (3) Preparation of actual water sample solution

[0045] Tap water from the campus of Bohai University, lake water from Tinglin Lake, and river water from Nv'er River in Jinzhou City were collected. Solid impurities in the actual water samples were filtered out and then used to prepare the test solutions. The three samples were then added with different concentrations of Ba 2+ The fluorescence emission signal at 490 nm was measured using a FL-4700 fluorescence spectrophotometer.

[0046] 3. Probe TpPa-COOH COF-HBT for Ba 2+ The selective performance of the probe TpPa-COOH COF-HBT was studied by fluorescence response to different cations, such as Figure 2 As shown in Figure 2, when excited at 366 nm, the probe TpPa-COOH COF-HBT was 2 The intensity of fluorescence emission in the O (5:5 / v:v) solvent system (probe concentration 10 mg / mL) was not high. 2+When (the concentration in the probe suspension is 5×10 -2 M), a significant fluorescence enhancement at 490 nm was observed. However, when other cations were added in equal molar amounts, no fluorescence enhancement was observed at 490 nm. This result indicates that the probe TpPa-COOH COF-HBT has a strong affinity for Ba 2+ It has excellent selectivity. The colorimetric properties of the fluorescent probe TpPa-COOHCOF-HBT in the presence of various metal ions are as follows Figure 3 (a) shows the fluorescence changes. Figure 3 (b) as shown.

[0047] 4. Probe TpPa-COOH COF-HBT recognizes Ba 2+ Anti-interference experiment

[0048] To investigate the effect of probe TpPa-COOH COF-HBT on Ba 2+ To test the recognition ability of the target protein, a competitive experiment was conducted with a probe concentration of 10 mg / mL (solvent: MeCN / H 2 O (5:5 / v:v). When various cations were added (concentration of 5×10 -2 M), only Ba at 490nm 2+ There is fluorescence enhancement. On this basis, an equimolar amount of Ba is added to other ion solutions. 2+ After that, the fluorescence intensity at 490nm was significantly enhanced. Figure 4 As shown in Figure 2, the probe TpPa-COOH COF-HBT can still specifically recognize Ba in the presence of other cations. 2+ , indicating that the probe TpPa-COOHCOF-HBT has good anti-interference ability.

[0049] Five, Ba 2+ The fluorescence titration and detection limit of the probe TpPa-COOH COF-HBT were used to study the effect of the probe TpPa-COOHCOF-HBT on Ba 2+ The sensing properties of Ba 2+ Fluorescence titration experiments were performed on TpPa-COOH COF-HBT ( Figure 5 ). Under the excitation of 366 nm, the probe TpPa-COOH COF-HBT was 2 The fluorescence intensity in BaO(5:5 / v:v) solution increases with the 2+ When the ion concentration in the system increases to 1 μM, its fluorescence intensity remains almost unchanged, indicating that the reaction system has reached saturation. 2+It has good sensing properties. In order to detect the practical application value of the probe, the detection limit of the probe TpPa-COOH COF-HBT was calculated. Based on the titration curve method, the detection limit of the probe TpPa-COOH COF-HBT for Ba 2+ The detection limit (LOD = 3σ / k) is 1.67×10 -8 M, such as Figure 6 As shown; the detection limit of compound C is 6.4×10 -6 M, indicating that the probe TpPa-COOH COF-HBT is effective for Ba 2+ The recognition has higher sensitivity.

[0050] VI. pH probe TpPa-COOH COF-HBT recognizes Ba 2+ Impact

[0051] In order to investigate the potential of the probe TpPa-COOH COF-HBT for practical applications, the effect of pH on the detection of Ba by the probe TpPa-COOHCOF-HBT was tested. 2+ The impact of Figure 7 As shown in Figure 2, the fluorescence intensity of the probe TpPa-COOH COF-HBT was not very high in the pH range of 1 to 13. The probe concentration was 10 mg / mL (solvent: MeCN / H 2 O(5:5 / v:v)); after adding Ba 2+ (The concentration in the probe suspension was 5×10 -2 After the reaction of M) with the probe TpPa-COOH COF-HBT, the fluorescence intensity was significantly enhanced and relatively stable in the pH range of 4 to 11. The experimental results show that when the pH is in the range of 4 to 11, the probe TpPa-COOH COF-HBT has a strong effect on Ba 2+ The recognition has a better response.

[0052] VII. Probe TpPa-COOH COF-HBT for Ba 2+ Time response

[0053] The time response spectrum is as follows Figure 8 As shown, the probe TpPa-COOH COF-HBT (probe concentration 10 mg / mL, solvent: MeCN / H 2 O (5:5 / v:v)) 2+ (The concentration in the probe suspension was 5×10 -2 After the reaction, the fluorescence intensity at 490 nm increased with time, and the reaction was completed within 10 minutes. 2+ The recognition has a faster time response.

[0054] 8. Detection of Ba in real water and food salt samples using the probe TpPa-COOH COF-HBT 2+

[0055] (1) Detection of Ba in real water samples using the probe TpPa-COOH COF-HBT 2+

[0056] In order to investigate the practical application of the probe TpPa-COOH COF, actual water sample tests were conducted. Lake water (Tinglin Lake, Bohai University), river water (Nv'er River, Jinzhou City) and tap water were selected as test water samples. The water samples were treated and filtered for the preparation of MeCN / H 2 O (5 / 5, v / v) mixed solution. Then the probe TpPa-COOH COF-HBT was added to make a 10 mg / mL test solution, and then different concentrations of Ba 2+ , record the fluorescence signal at 490nm. Fig. 9 and Fig.10 As shown, the fluorescence intensity of the probe is related to Ba 2 + The concentration has an excellent linear relationship in the range of 0.6-1mM (R 2 >0.99), as shown in Table 1, the relative deviation (RSD) was in the range of 0.14% to 1.44%, and the recovery of the method was between 97.96% and 102.60%, indicating that the probe TpPa-COOH COF-HBT can be used for the quantitative detection of Ba 2+ .

[0057] Table 1 Probe TpPa-COOH COF-HBT in water sample analysis and test Ba 2+ result.

[0058]

[0059] (2) Detection of Ba in food salt samples using the probe TpPa-COOH COF-HBT 2+

[0060] Many times, salts obtained by drying polluted seawater may contain barium ions. Therefore, the TpPa-COOH COF-HBT was studied for the determination of Ba in granular salt samples. 2+ Dissolve salts purchased from supermarkets from different manufacturers in MeCN / H 2O (5 / 5, v / v) mixed solution to prepare the real samples. As shown in Table 2, the relative deviation (RSD) ranged from 1.01% to 2.19%, and the recovery of the method ranged from 98.11% to 101.48%, indicating that the probe TpPa-COOH COF-HBT can be used to detect different concentrations of Ba in food samples. 2+ .

[0061] Table 2 Probe TpPa-COOH COF-HBT analysis and testing of Ba in two salt samples 2+ result.

[0062]

[0063] The above are only specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for identifying heavy metal Ba 2+ The functionalized covalent organic framework fluorescent probe is characterized by: The structural formula is as follows: ； Where R2 is .

2. The method for identifying heavy metal Ba according to claim 1. 2+ The functionalized covalent organic framework fluorescent probe is characterized by: The specific synthesis process of the covalent organic framework fluorescent probe is as follows: (1) Compound A Water was added to prepare a COF suspension, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide were added to react at room temperature for 4 hours to obtain compound B. ; 2 mol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide was added per 100 g of compound A to carry out the reaction; The molar ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 1:1.5; (2) Take another 0.25 g of compound C Add ethanol to dissolve, add to the compound B synthesized in step (1), react at room temperature for 24 hours, the mass ratio of the compound C to the compound A is 5:1; then centrifuge, retain the solid, and wash with dichloromethane until the solvent is colorless to obtain a compound for identifying heavy metal Ba 2+ Functionalized covalent organic framework fluorescent probes , where R2 is .

3. The method for identifying heavy metal Ba according to claim 2 2+ The functionalized covalent organic framework fluorescent probe is characterized by: The mass volume ratio of the compound C to ethanol is 0.01 g / mL.

4. The method for identifying heavy metal Ba according to claim 2 2+ The functionalized covalent organic framework fluorescent probe is characterized by: The concentration of the COF suspension was 5 mg / mL.

5. A functionalized covalent organic framework fluorescent probe as claimed in claim 1 for identifying heavy metal Ba for non-diagnostic purposes 2 + Application in.

6. The use according to claim 5, characterized in that: The functionalized covalent organic framework fluorescent probe can selectively recognize the heavy metal Ba 2+ The solvent system is acetonitrile and water in a volume ratio of 5:

5.

7. The use according to claim 5, characterized in that: The functionalized covalent organic framework fluorescent probe was added to the test water sample, and its fluorescence emission intensity was measured at an excitation wavelength of λ=366nm. The fluorescence intensity at 490nm was significantly enhanced. The test water sample contained heavy metal Ba 2+ .

8. The use according to claim 5, characterized in that: The functionalized covalent organic framework probe is 2+ The detection limit was 1.67×10 -8 mol / L.

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