Preparation and application of porphyrin-based metal organic complex fluorescent probe Ni-TCPP

Abstract

The invention belongs to the field of analysis of radioactive elements, and discloses preparation and application of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP. The method comprises the following steps: dissolving a solid mixture of NiCl3. 6H2O and PVP in a centrifugal tube containing a DMF / ethanol mixed solution; then slowly adding TCPP into the centrifugal tube, and carrying out ultrasonic treatment; finally, the solution is transferred into a PTFE lining, and then the PTFE lining is sealed in a stainless steel autoclave to be treated; and after the reaction is completed, centrifuging, cooling to room temperature, washing, and drying overnight to obtain the Ni-TCPP. Compared with other MOF light-emitting sensing materials, the MOF light-emitting sensing material disclosed by the invention has the advantages that the long-wavelength fluorescence characteristic similar to that of a rare earth doped material can be maintained, and meanwhile, the MOF light-emitting sensing material responds to ultra-low-concentration uranyl ions (16.59 nM) and has higher specificity, higher sensitivity and huge practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive element analysis, and more specifically to the development of a non-rare earth-doped MOF bifunctional fluorescent probe and its application in the detection of uranyl ions in real seawater. Background Art

[0002] With the development of human society and technology, uranium has been increasingly used in a wide range of fields, including nuclear weapons, nuclear power plants, and medical treatment. However, uranium is a toxic metal ion with radioactivity and a long half-life. It can enter the human body and damage the human body by affecting the functions of organs such as the lungs and kidneys. In the process of uranium application, a large amount of uranium-containing waste is released into the environment, posing a serious threat to human health. Among the many valence states of uranium, uranyl (UO2 2+ ) is the most stable form of uranium, which makes it easily diffuse into the environment through the natural water cycle.

[0003] In recent years, many conventional analytical strategies for detecting uranyl ions have been proposed, such as inductively coupled plasma-optical emission spectroscopy (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), accelerator mass spectrometry (AMS), electrochemical methods (EA), etc. However, these detection methods have limitations such as slow detection speed, complex sample pretreatment, and expensive instruments. In contrast, fluorescence sensing has the advantages of low cost, convenient detection process, easy operation, and real-time detection. So far, a series of sensors based on nanomaterial fluorescence have been designed for uranyl ion detection, such as silver nanoparticle-modified reduced graphene oxide (rGO) nanosheet materials, ratiometric fluorescence probes integrating carbon quantum dots (CD) and CdTe quantum dots (QD) by chemical hybridization, and self-enhanced electroluminescence imaging systems based on amidoxime-functionalized polymer nanoparticles.

[0004] Among these nanomaterials, metal organic framework (MOF) materials stand out due to their porosity, large specific surface area, multiple metal sites and excellent chemical stability. The material exhibits fluorescence when exposed to external stimuli and can be used to construct a dual-functional platform through which various pollutants can be detected and removed. However, high cost and complex synthesis process are currently stumbling blocks to the development of MOFs.

[0005] Therefore, it is imperative to explore a preparation method for MOF materials that is simple, easy, selective, sensitive, simple to prepare, and low-cost. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a preparation of a porphyrin-based metal oxide fluorescent probe Ni-TCPP and its application in the detection of uranyl ions in real seawater. The present invention creatively develops a fluorescent probe that can simultaneously visualize the detection and removal of uranyl, a common pollutant in seawater, by combining the optical and adsorption properties of Ni-TCPP, which has higher specificity, higher sensitivity and great practical application value.

[0007] One of the purposes of the present invention is to provide a method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP, comprising dissolving a solid mixture of nickel (II) chloride hexahydrate (NiCl3·6H2O) and polyvinyl pyrrolidone (PVP) in a centrifuge tube containing an N,N-dimethylformamide (DMF) / ethanol mixed solution; then slowly adding tetrakis(4-carboxyphenyl)porphyrin (TCPP) into the centrifuge tube and performing ultrasonic treatment; finally, transferring the solution into a PTFE liner and then sealing it in a stainless steel autoclave for treatment; when the reaction is completed, centrifuging the obtained mixture twice with DMF as a solvent, cooling it to room temperature, washing the Ni-TCPP solid product twice with ultrapure water and anhydrous ethanol respectively, and drying the washed solid product overnight to obtain the Ni-TCPP.

[0008] The specific steps include:

[0009] (1) dissolving nickel (II) chloride hexahydrate and polyvinyl pyrrolidone in a N,N-dimethylformamide / ethanol mixed solution, mixing well to obtain solution A, which is set aside;

[0010] (2) slowly adding tetrakis(4-carboxyphenyl)porphyrin to the solution A, ultrasonically treating for 15 min, and mixing evenly to obtain solution B for later use;

[0011] (3) transferring the solution B to a PTFE liner and sealing it in a stainless steel autoclave;

[0012] (4) After the reaction is completed, centrifuge, cool to room temperature, wash, and dry overnight to obtain Ni-TCPP.

[0013] Preferably, in step (1), the mass ratio of the nickel (II) chloride hexahydrate to polyvinyl pyrrolidone is 0.5-1:0.35-0.75; the solid-liquid ratio of the nickel (II) chloride hexahydrate to the N,N-dimethylformamide / ethanol mixed solution is 0.5-1:20-40 g / mL; and the volume ratio of N,N-dimethylformamide to ethanol in the N,N-dimethylformamide / ethanol mixed solution is 3-5:1.

[0014] Preferably, in step (2), the mass ratio of the tetrakis(4-carboxyphenyl)porphyrin to the nickel(II) chloride hexahydrate is 0.1-0.5:0.5-1.

[0015] Preferably, in step (3), the temperature of the closed treatment is 80 to 120° C., and the time is 12 to 24 hours.

[0016] Preferably, in step (4), after the reaction is completed, the obtained mixture is centrifuged twice with DMF as solvent, cooled to room temperature, and the Ni-TCPP solid product is washed twice with ultrapure water and anhydrous ethanol respectively, and the washed solid product is dried overnight to obtain Ni-TCPP.

[0017] Preferably, the centrifugation speed is 10000 rpm, and each time lasts 10 min; the solid product is dried overnight at 50° C. in a vacuum chamber.

[0018] The second object of the present invention is to provide a porphyrin-based metal organic complex fluorescent probe Ni-TCPP.

[0019] The third object of the present invention is to provide an application of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP in fluorescent detection of uranyl ions, which is used for simultaneous visual detection and removal of uranyl ions in seawater.

[0020] Furthermore, the specific method for simultaneously visually detecting and removing uranyl ions in seawater is:

[0021] The porphyrin-based metal organic complex fluorescent probe Ni-TCPP was dispersed in ultrapure water and ultrasonically treated for at least 0.5 h to obtain a probe solution; different amounts of UO2 were added to the probe solution. 2+ The solution was mixed to reach its final concentration and then subjected to fluorescence detection.

[0022] Preferably, the ultrasonic treatment time is 0.5 to 1 h.

[0023] Preferably, the probe solution has a concentration of 1 to 10 μM.

[0024] Preferably, the addition of different amounts of UO2 2+ The final concentration of the solution is 0-200 μM.

[0025] Preferably, the excitation wavelength used in the fluorescence detection is 360-370 nm, the scanning rate is 1200 nm / min, and the fluorescence spectrum range of the sample captured is 600-700 nm.

[0026] The technical concept of the present invention is: currently, most MOF materials widely used for uranyl ion detection are rare earth-doped and have a fluorescence quenching mechanism. In view of this, the fluorescent probe designed by the present invention is a red fluorescence-enhanced, non-rare earth-doped MOF probe with the ability to resist background interference. The present invention creatively develops a fluorescent probe that can simultaneously visualize the detection and removal of uranyl, a common pollutant in seawater, by combining the optical and adsorption properties of Ni-TCPP. TCPP itself can show bright red fluorescence, and the fluorescence disappears after reacting with Ni. When it comes into contact with uranyl ions, UO2 2+ After interacting with Ni-TCPP, the structure of Ni-TCPP collapses, causing the red fluorescence to "turn on" and increase. At the same time, after the Ni-TCPP structure collapses, the surface of the organic molecules in the collapsed structure can adsorb uranyl ions, further enhancing the adsorption capacity for uranyl ions.

[0027] It can be seen from the above technical solution that, compared with the prior art, the beneficial effects achieved by the present invention are:

[0028] 1. By combining the optical and adsorption properties of Ni-TCPP, a dual-functional platform for sensing and removal of uranyl in actual seawater samples was creatively developed, which has higher specificity and sensitivity while maintaining long-wavelength fluorescence properties similar to those of rare earth-doped materials, demonstrating great potential for practical applications.

[0029] 2. In terms of uranyl ion detection, this fluorescent probe can respond to ultra-low concentrations of uranyl ions with a detection limit as low as 16.59nM, and through an effective luminescence "turn-on" mechanism, it has become one of the most sensitive MOF-based luminescent sensing materials.

[0030] 3. In terms of uranyl ion adsorption and removal, the fluorescent probe has a good effect on UO2 2+ The maximum adsorption capacity is 18.74 mg / g, showing excellent adsorption capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 This is the SEM image of Ni-TCPP.

[0033] Figure 2 FT-IR spectra of TCPP and Ni-TCPP.

[0034] Figure 3 The XRD spectra of NiCl3·6H2O, TCPP and Ni-TCPP. Attached: Picture of Ni-TCPP.

[0035] Figure 4 Figure 1 is the fluorescence spectrum of Ni-TCPP (0.1 mg / mL) before and after the addition of uranyl ions (200 μM). Attached: Photos of 0.1 mg / mL Ni-TCPP before and after the addition of uranyl ions under UV light.

[0036] Figure 5 The UV-visible absorption spectra of Ni-TCPP (0.1 mg / mL) before and after the addition of uranyl ions (200 μM). Attached: Photos of Ni-TCPP (0.1 mg / mL) before and after the addition of uranyl ions.

[0037] Figure 6 The fluorescence spectra of Ni-TCPP (0.1 mg / mL) in the presence of different concentrations of uranyl ions (0-90 μM).

[0038] Figure 7 It is the relationship between the presence of uranyl ions and the concentration of uranyl ions in the range of 0 to 90 μM (F-F0).

[0039] Figure 8 This is a bar graph showing the fluorescence response of Ni-TCPP to uranyl ions in the presence of interfering ions.

[0040] Fig. 9 This is a test on the peak value and recovery rate of uranyl ions in actual seawater samples. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] Preparation of Ni-TCPP

[0044] For Ni-TCPP, a solid mixture of 0.5 g nickel (II) chloride hexahydrate (NiCl3·6H2O) and 0.35 g polyvinyl pyrrolidone (PVP) was dissolved in a 50 mL centrifuge tube containing 20 mL N, N-dimethylformamide (DMF) / ethanol (volume ratio of 3:1) mixed solution. Subsequently, 0.1 g tetrakis (4-carboxyphenyl) porphyrin (TCPP) was slowly added to the centrifuge tube and then ultrasonically treated for 15 min. Finally, the solution was transferred to a 50 mL PTFE liner, which was then sealed in a stainless steel autoclave and treated at 80 ° C for 24 h. When the reaction was completed, the received mixture was centrifuged twice at a speed of 10000 rpm for 10 min using DMF as a solvent and cooled to room temperature. Then, the Ni-TCPP solid product was washed twice with ultrapure water and anhydrous ethanol, respectively. The rinsed solid product was dried overnight at 50 ° C in a vacuum chamber to obtain Ni-TCPP.

[0045] Example 2

[0046] Preparation of probes

[0047] The synthesized Ni-TCPP solid was directly dispersed in ultrapure water (pH = 5) and treated with ultrasound for 0.5 h to prepare a probe solution with a concentration of 1 μM.

[0048] Experiment 1: Fluorescence response of the probe to uranyl ions

[0049] In order to evaluate the response of Ni-TCPP to uranyl ions, different amounts of uranyl ion solution were added to the probe solution with a final concentration of 0-200 μM. After the sample was mixed evenly, the fluorescence spectrum of the sample in the range of 600-700 nM was recorded under the conditions of excitation wavelength 365 nM and scanning rate 1200 nm / min. When the probe was dissolved in ultrapure water at pH = 5, Ni-TCPP was almost non-fluorescent. When uranyl ions were added, the onset of red fluorescence was monitored at 649 nM due to the collapse of the Ni-TCPP framework ( Figure 4 The fluorescence intensity of the probe fluctuates with the increase of uranyl ion concentration (0-200 μM). Figure 6 It showed that the fluorescence intensity appeared at 649 nM, and the fluorescence intensity increased to 181.3, and red fluorescence appeared, which could be used as a fluorescent probe to detect uranyl ions. Figure 7 It shows that there is a positive linear relationship between (F-F0) and the uranyl ion content, and the correlation coefficient (R 2 ) is 0.999, and the detection limit (LOD) of uranyl ion is 16.59nM, and the derivation formula is: LOD = 3σ / k 32 .

[0050] Experiment 2: Selectivity of the fluorescence response of the probe to other metal ions and anions

[0051] 200 μM probe solution (1.0 mg / mL) was added to 1800 μM ultrapure water (pH = 5) to prepare 2 mL probe solution. 2+ , Tb 3+ , Ni 2+ , Na + , Mn 2+ ,Mg 2+ , K + , Fe 3+ ,Eu 3+ , Cu 2+ ,Cr 3+ , Cd 2+ , Ba 2+ , Al 3+ ,CO3 2- , HCO3 - , NO3 - , NO2 - , I - , IO3 - and SO4 2- ) as interfering ions to investigate the selectivity and anti-interference of Ni-TCPP. When interfering ions are added, the fluorescence response of Ni-TCPP to uranyl ions will not be seriously affected, indicating that Ni-TCPP has good anti-interference performance for the fluorescence detection of uranyl ions ( Figure 8 ).

[0052] Experiment 3: Application of the probe in actual seawater samples

[0053] In order to verify the practical application ability of Ni-TCPP in detecting uranyl ions in real seawater samples, seawater samples were collected in the sea area of ​​Maoming City, Guangdong Province. After filtering with a 0.45μM membrane to remove suspended solids, different concentrations of uranyl ions (50, 100, 150, 200μM) were added to the seawater samples, and then fluorescence detection experiments were carried out. The spike and recovery tests were also carried out on real seawater samples ( Fig. 9 ). The recovery (%) was calculated as the ratio of the amount of quantified uranyl ions to the amount of spiked sample. Three separate tests were repeated under the same settings to determine the relative standard deviation or RSD.

[0054] Fig. 9 The recoveries of real seawater samples ranged from 88.2% to 109.3%, with relative standard deviations (RSDs) of 3.6% to 5.9%. The results indicate that Ni-TCPP is a promising fluorescent sensor for the determination of uranyl ions in real seawater samples.

[0055] Example 3

[0056] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of nickel chloride (II) hexahydrate used is 0.75 g and the amount of PVP used is 0.55 g.

[0057] Example 4

[0058] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of nickel chloride (II) hexahydrate used is 1 g and the amount of PVP used is 0.75 g.

[0059] Example 5

[0060] The preparation of Ni-TCPP is similar to that of Example 1, except that the volume ratio of N,N-dimethylformamide (DMF) to ethanol in the N,N-dimethylformamide (DMF) / ethanol mixed solution is 4:1.

[0061] Example 6

[0062] The preparation of Ni-TCPP is similar to that of Example 1, except that the volume ratio of N,N-dimethylformamide (DMF) to ethanol in the N,N-dimethylformamide (DMF) / ethanol mixed solution is 5:1.

[0063] Example 7

[0064] The preparation of Ni-TCPP is similar to that of Example 1, except that the volume of the N,N-dimethylformamide (DMF) / ethanol mixed solution is 30 mL.

[0065] Example 8

[0066] The preparation of Ni-TCPP is similar to that of Example 1, except that the volume of the N,N-dimethylformamide (DMF) / ethanol mixed solution is 40 mL.

[0067] Example 9

[0068] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of TCPP used is 0.2 g.

[0069] Example 10

[0070] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of TCPP used is 0.3 g.

[0071] Embodiment 11

[0072] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of TCPP used is 0.4 g.

[0073] Example 12

[0074] The preparation of Ni-TCPP is similar to that of Example 1, except that the amount of TCPP used is 0.5 g.

[0075] Embodiment 13

[0076] The preparation of Ni-TCPP is similar to that of Example 1, except that the temperature of the treatment in the stainless steel autoclave is 100° C. and the duration is 18 h.

[0077] Embodiment 14

[0078] The preparation of Ni-TCPP is similar to that of Example 1, except that the temperature of the treatment in the stainless steel autoclave is 120° C. and the duration is 24 h.

[0079] Embodiment 15

[0080] The preparation of the probe is similar to that of Example 2, except that the concentration of the probe solution is 5 μM.

[0081] Example 16

[0082] The preparation of the probe is similar to that of Example 2, except that the concentration of the probe solution is 10 μM.

[0083] Embodiment 17

[0084] The preparation of the probe is similar to that of Example 2, except that the ultrasonic treatment time is 0.75 h.

[0085] Embodiment 18

[0086] The preparation of the probe is similar to that of Example 2, except that the ultrasonic treatment time is 1 h.

[0087] Embodiment 19

[0088] The fluorescence response of the probe to uranyl ions was similar to that in Experiment 1, except that the excitation wavelength used in the fluorescence detection was 360 nM.

[0089] Embodiment 20

[0090] The fluorescence response of the probe to uranyl ions was similar to that in Experiment 1, except that the excitation wavelength used in the fluorescence detection was 370 nM.

[0091] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP, characterized in that: The fluorescent probe Ni-TCPP is prepared by a one-pot hydrothermal method using nickel chloride hexahydrate as a nickel source and tetrakis (4-carboxyphenyl) porphyrin as an organic ligand.

2. The method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP according to claim 1, characterized in that: The following steps are involved: (1) dissolving nickel (II) chloride hexahydrate and polyvinyl pyrrolidone in a N,N-dimethylformamide / ethanol mixed solution, mixing well to obtain solution A, which is set aside; (2) slowly adding tetrakis(4-carboxyphenyl)porphyrin to the solution A, ultrasonically treating, and mixing evenly to obtain a solution B for later use; (3) transferring the solution B to a PTFE liner and sealing it in a stainless steel autoclave; (4) After the reaction is completed, centrifuge, cool to room temperature, wash, and dry overnight to obtain Ni-TCPP.

3. A method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP according to claim 1, characterized in that: In step (1), the mass ratio of the nickel (II) chloride hexahydrate to polyvinyl pyrrolidone is 0.5-1:0.35-0.75; the solid-liquid ratio of the nickel (II) chloride hexahydrate to the N,N-dimethylformamide / ethanol mixed solution is 0.5-1:20-40 g / mL; and the volume ratio of N,N-dimethylformamide to ethanol in the N,N-dimethylformamide / ethanol mixed solution is 3-5:

1.

4. The method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP according to claim 1, characterized in that: In step (2), the mass ratio of the tetrakis(4-carboxyphenyl)porphyrin to the nickel(II) chloride hexahydrate is 0.1-0.5:0.5-1.

5. The method for preparing a porphyrin-based metal organic complex fluorescent probe Ni-TCPP according to claim 1, characterized in that: In step (3), the temperature of the sealed treatment is 80 to 120° C. and the time is 12 to 24 hours.

6. A porphyrin-based metal organic complex fluorescent probe Ni-TCPP obtained by the preparation method according to any one of claims 1 to 5.

7. Application of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP in fluorescent detection of uranyl ions, characterized in that: The porphyrin-based metal organic complex fluorescent probe Ni-TCPP as claimed in claim 6 can simultaneously visualize the detection and removal of uranyl ions.

8. The use of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP in fluorescent detection of uranyl ions according to claim 7, characterized in that: The specific method is: The porphyrin-based metal organic complex fluorescent probe Ni-TCPP was dispersed in ultrapure water and ultrasonically treated to obtain a probe solution; UO2 was added to the probe solution. 2+ The solution was mixed to reach its final concentration and then subjected to fluorescence detection.

9. The use of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP in fluorescent detection of uranyl ions according to claim 8, characterized in that: The probe solution concentration is 1-10 μM, and the final concentration is 0-200 μM.

10. The use of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP in fluorescent detection of uranyl ions according to claim 8, characterized in that: The excitation wavelength used in the fluorescence detection is 360-370 nm, the scanning rate is 1200 nm / min, and the fluorescence spectrum range captured by the sample is 600-700 nm.

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