A rare earth complex material, a preparation method and application thereof

Abstract

The application belongs to the field of rare earth metal material synthesis, and discloses a rare earth complex material and a preparation method and application thereof. The rare earth complex material is prepared by a volatilization method, and is composed of a rare earth (III) element, 2,3,4,5,6-pentafluorobenzoic acid and 4,7-dimethyl-1,10-phenanthroline. The preparation method is simple and easy to operate, and does not require valuable and precise instruments and equipment. The rare earth complex material has excellent fluorescence performance, can selectively recognize specific Cd 2+ under specific environment, and can be used as a fluorescence probe for detecting Cd 2+ . The fluorescence probe has the characteristics of low detection limit, strong anti-interference and fast response time, and can be used for detecting Cd 2+ . The rare earth complex material is used as raw material to prepare a portable test paper sensing detection device, so that rapid and visible detection of Cd 2+ can be realized.

Description

Technical Field

[0001] This invention belongs to the field of rare earth metal material synthesis, specifically relating to a rare earth complex material, its preparation method, and its application. Background Technology

[0002] Cadmium is a highly toxic heavy metal, and its compounds are also toxic. Industrial wastewater containing cadmium pollutes rivers and farmland. Cadmium is more easily absorbed by crops, vegetables, and rice than other heavy metals. When people consume contaminated crops, cadmium enters the body through the digestive tract, primarily accumulating in the liver and kidneys, causing damage. Due to the long-term and insidious nature of cadmium pollution, it can replace calcium in bones, causing severe softening and fractures. Cadmium can also cause gastrointestinal dysfunction, lowering the zinc-cadmium ratio and leading to increased hypertension. The most harmful pathway for cadmium to harm human health is through "cadmium-contaminated rice." Cadmium-contaminated rice generally refers to rice with excessive cadmium content. Cadmium ions typically enter the environment through wastewater and then enter food through irrigation; rice is a typical "victim crop." Given these hazards, accurately detecting the cadmium content in rice is an urgent problem that needs to be solved.

[0003] Currently, Cd 2+ The main detection methods for Cd include atomic absorption spectrometry, hydride generation-atomic fluorescence spectrometry, spectrophotometry, high-performance liquid chromatography, and electrochemical methods. However, these methods are time-consuming and expensive. In contrast, fluorescent probe methods have high sensitivity and selectivity, and can rapidly and specifically detect Cd. 2+ It has obvious advantages and is considered to be the detection method for Cd. 2+ One of the good methods for detecting Cd is fluorescent probes. However, fluorescent probe methods are expensive and the preparation methods are relatively complex. Therefore, there is an urgent need to find a method for preparing fluorescent probes that uses inexpensive raw materials, is simple to operate, and has excellent sensitivity for detecting Cd. 2+ .

[0004] Rare earth complexes possess diverse coordination geometries, unique magnetism, and stability, exhibiting distinctive optical properties generated through the antenna effect, including large Stokes shifts, stable emission bands, and long luminescence lifetimes, making them ideal luminescent sensing materials. In rare earth complex fluorescent probes, organic ligands can sensitize rare earth ions through the "antenna effect," emitting strong characteristic fluorescence. This high-intensity characteristic fluorescence can interact with some non-fluorescent metal cations, leading to the quenching of the rare earth complex's fluorescence. This change in the complex's luminescent properties can be used to identify and detect the presence of metal cations.

[0005] Rare earth complex fluorescent probes possess unique optical properties, offering advantages such as low sample volume, fast analysis speed, high sensitivity, and low detection limit. However, how to achieve the desired results for Cd... 2+Specific detection, especially for Cd in real-world environments. 2+ Further research is needed to explore suitable rare earth metals and organic ligands to construct rare earth metal complex materials that can serve as detection targets. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rare earth complex material, its preparation method, and its application. Specifically, the following technical solution is adopted:

[0007] According to a first aspect of the present invention, a method for preparing rare earth complexes is provided, comprising the following steps:

[0008] First, a solution of rare earth soluble salt and deprotonated 2,3,4,5,6-pentafluorobenzoic acid is added to a first solvent and mixed to obtain a mixed solution A; the first solvent is water or an organic solvent. Then, 4,7-dimethyl-1,10-phenanthroline and the obtained mixed solution A are added to a second solvent to obtain a mixed solution B; the second solvent is an organic solvent. Finally, the obtained mixed solution B is sealed, leaving pores, and the rare earth complex material is obtained after the organic solvent has completely evaporated.

[0009] This invention prepares rare earth complex materials via a volatilization method. These complex materials are composed of rare earth (III) elements, the first ligand 2,3,4,5,6-pentafluorobenzoic acid (HPFBA), and the auxiliary ligand 4,7-dimethyl-1,10-phenanthroline. This preparation method is simple and easy to implement, requiring no expensive or sophisticated equipment, making it more suitable for industrial production.

[0010] In this invention, 2,3,4,5,6-pentafluorobenzoic acid is selected as the first ligand. On one hand, for metal ions, energy transfer is considered an important quenching mechanism; that is, the ligand in the complex absorbs light, and then electrons transfer from the ground state S0 to the excited singlet state S1. The lifetime of the singlet state S1 is very short. After crossing to the lowest excited state T1, energy is transferred from the minimum excited triplet state T1 to the rare earth ion via energy transfer, and electrons from the ground state to the ground state rare earth ion, thus emitting light. Since the carboxyl group of pentafluorobenzoic acid in the rare earth complex material of this invention has an uncoordinated oxygen atom, this uncoordinated oxygen can react with Cd... 2+ Effective binding hinders the energy transfer from the lowest excited triplet state T1 to the rare earth ion, leading to energy transfer from the ligand to Cd. 2+ This promotes fluorescence quenching; on the other hand, because the 2,3,4,5,6-pentafluorobenzoic acid ligand does not have an oscillating group, the above-mentioned energy transfer efficiency is higher.

[0011] The use of 4,7-dimethyl-1,10-phenanthroline as an auxiliary ligand makes the structure of the final rare earth complex material more stable, and it can maintain excellent stability even when placed in pH 2-13 and in different organic solvents.

[0012] Preferably, the rare earth soluble salt is any one of nitrate, chloride, acetate, sulfonate, oxalate and trifluoromethanesulfonate.

[0013] Preferably, the preparation process of the deprotonated 2,3,4,5,6-pentafluorobenzoic acid solution is as follows: 2,3,4,5,6-pentafluorobenzoic acid is dissolved in water, and then the pH is adjusted to 6.0 with NaOH solution (0.1M) to obtain the deprotonated 2,3,4,5,6-pentafluorobenzoic acid solution; the ratio of 2,3,4,5,6-pentafluorobenzoic acid to water is 10 mg: 1 mL. The pH is adjusted by adding at least one alkaline solution selected from sodium hydroxide, potassium hydroxide, triethylamine, and ammonia water to the 2,3,4,5,6-pentafluorobenzoic acid solution.

[0014] Preferably, the ratio of the first solvent, 2,3,4,5,6-pentafluorobenzoic acid, and rare earth soluble salt is (2mL-8mL):10mg:6.7mg.

[0015] Preferably, the second solvent is at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, methanol, acetonitrile, ethanol, acetone, acetylacetone, dichloromethane, and chloroform. The ratio of the second solvent to 4,7-dimethyl-1,10-phenanthroline is 2 mL: 3.1 mg.

[0016] Preferably, the environmental conditions for the evaporation of the organic solvent are any one of conventional atmospheric, nitrogen, oxygen, and argon atmospheres. More preferably, the environmental conditions for the evaporation of the organic solvent are conventional atmospheric, and the evaporation time is 20-32 days.

[0017] According to a second aspect of the present invention, a rare earth complex material is also provided, which is prepared by the above-described preparation method.

[0018] According to a third aspect of the present invention, a rare earth complex material is also provided as a test paper or fluorescent probe for the detection of Cd. 2+ Applications in this area. As a fluorescent probe, it is mainly used in three environments: water, rice powder supernatant, and rice soil supernatant, to detect the heavy metal Cd. 2+ It features low detection limit, strong anti-interference ability, and fast response time; as a test strip, it can detect Cd. 2+ It offers rapid and visible detection, is simple and convenient to operate, and has high sensitivity.

[0019] The beneficial effects of this invention are as follows: the preparation method is simple and easy to implement, the raw materials used are inexpensive and readily available, and no expensive and precision instruments or equipment are required, making it more suitable for industrial production. The rare earth complex material prepared by this invention exhibits excellent fluorescence properties and can selectively identify specific Cd under three environments (water, rice powder supernatant, and rice soil supernatant). 2+ This quenching effect on its fluorescence signal can be used as a fluorescent probe for Cd. 2+ The detection of Cd and its use as a fluorescent probe. 2+ Featuring low detection limit, strong anti-interference ability, and fast response time, this invention also uses this rare earth complex as a raw material to prepare a portable test strip sensing device for Cd detection. 2+ Rapid and visible detection. Attached Figure Description

[0020] Figure 1 The image shows the PXRD patterns of rare earth complex material (1-Tb) after being soaked in different pH and solvents for 28 hours and then centrifuged and dried.

[0021] Figure 2 The image shows a rare earth complex material (1-Tb) combined with 20 different substances (Ba) in a deionized water environment. 2 + Ca 2+ Cd 2+ Co 3+ NH4 + Mg 2+ ,Mn 2+ Cu 2+ ,K + C6H5COO - AlO3 3- SiO3 2- C7H7O3S - B4O7 2- C6H5O7 3- (C6H5)4B - CH3COO - WO4 2- SO4 2- SO3 2- The bar chart after (excitation wavelength 335nm, with the highest characteristic peak at 534nm selected);

[0022] Figure 3 The figure shows the effect of rare earth complex material (1-Tb) on Cd. 2+ The detection limit spectrum (excitation wavelength 335 nm);

[0023] Figure 4The figure shows the effect of rare earth complex material (1-Tb) on Cd. 2+ The response curve (excitation wavelength 335nm);

[0024] Figure 5 The image shows the anti-interference results of the rare earth complex material (1-Tb) (excitation wavelength is 335nm);

[0025] Figure 6 The image shown is a photograph obtained by immersing test paper made of rare earth complex material (1-Tb) in 20 different ions. Detailed Implementation

[0026] The following will provide a clear and complete description of the concept and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0027] Example 1

[0028] A rare earth complex material (1-Tb) is prepared by the following steps:

[0029] S1. Dissolve 6.7 mg of terbium nitrate hexahydrate in 2.0 mL of tetrahydrofuran to obtain a terbium nitrate solution;

[0030] S2. Place 10.0 mg of 2,3,4,5,6-pentafluorobenzoic acid in a beaker, add 1.0 mL of water, and then adjust the pH of the 2,3,4,5,6-pentafluorobenzoic acid solution to 6.0 with 0.1 M sodium hydroxide solution to obtain a deprotonated 2,3,4,5,6-pentafluorobenzoic acid solution; slowly add the deprotonated 2,3,4,5,6-pentafluorobenzoic acid solution dropwise to the rare earth salt solution obtained in step S1 and mix well to obtain mixed solution A;

[0031] S3. Dissolve 3.1 mg of 4,7-dimethyl-1,10-phenanthroline in 2.0 mL of ethanol, and then add it to the mixed solution A obtained in step S2 and mix well to obtain mixed solution B.

[0032] S4. Place the obtained mixed solution B in a 10.0 mL beaker, seal it with plastic wrap and poke a hole, let it stand at room temperature for 28 days, and obtain 3.022 g of colorless blocky crystals, denoted as 1-Tb.

[0033] Example 2

[0034] A rare earth complex material (1-Eu) is prepared by simply changing "6.7 mg of terbium nitrate hexahydrate dissolved in 2.0 mL of tetrahydrofuran" in step S1 to "6.7 mg of europium nitrate hexahydrate dissolved in 2.0 mL of tetrahydrofuran". The other steps are the same as in Example 1, and 3.186 mg of colorless blocky crystals are obtained, which are denoted as 1-Eu.

[0035] Example 3

[0036] A rare earth complex material (2-Tb) is prepared by simply changing "6.7 mg of terbium nitrate hexahydrate dissolved in 2.0 mL of tetrahydrofuran" in step S1 to "terbium chloride hexahydrate dissolved in 8.0 mL of deionized water". The other steps are the same as in Example 1, and 3.379 mg of colorless blocky crystals are obtained, which are denoted as 2-Tb.

[0037] Example 4

[0038] A rare earth complex material (3-Tb) is prepared by simply changing "6.7 mg of terbium nitrate hexahydrate dissolved in 2.0 mL of tetrahydrofuran" in step S1 to "terbium chloride hexahydrate dissolved in 4.0 mL of ethanol". The other steps are the same as in Example 1, and 2.112 mg of colorless blocky crystals are obtained, which are denoted as 3-Tb.

[0039] Example 5

[0040] The inventors also conducted relevant tests on the rare earth complex material (1-Tb) obtained in Example 1.

[0041] (1) Stability testing of rare earth complex materials, specifically including the following steps:

[0042] 1-Tb powder was soaked in rice powder supernatant, rice soil supernatant, aqueous solutions of different pH values, and six organic solvents (methanol, ethanol, acetonitrile, acetone, tetrahydrofuran, and acetylacetone) for 28 hours, then centrifuged, dried, and subjected to PXRD analysis. The test results are as follows: Figure 1 As shown.

[0043] Depend on Figure 1 The results show that the PXRD test results are in good agreement with the simulated crystal peaks, indicating that the rare earth complex material prepared by this invention has excellent stability.

[0044] (2) Study on the fluorescence properties of rare earth complex (1-Tb) materials, specifically including the following steps:

[0045] Dissolve 5.0 mg of 1-Tb powder in 5 mL of DMF to obtain a 1-Tb DMF solution. Take 50 μL of the 1-Tb DMF solution and add it to 4.9 mL of deionized water. Divide the solution into 20 portions. Add 50 μL of deionized water to one portion as a blank sample. Add 50 μL of Cd to another portion.2+ Solution (1.0×10 -3 M) (solvent is deionized water), and finally, Cd is added to the other groups respectively. 2+ Solution (1.0×10 -3 M) (solvent is deionized water) and 19 other different substances in equal concentrations and solvents (Ba 2+ Ca 2+ Co 3+ NH4 + Mg 2+ ,Mn 2+ Cu 2+ ,K + C6H5COO - AlO3 3- SiO3 2- C7H7O3S - B4O7 2- C6H5O7 3- (C6H5)4B - CH3COO - WO4 2- SO4 2- SO3 2- Under the same conditions, fluorescence performance was tested (excitation wavelength 335 nm), and the test results are as follows. Figure 2 As shown.

[0046] Depend on Figure 2 The bar chart shows that the blank 1-Tb DMF solution obtained the largest emission peak at 534 nm. Compared with the addition of other different substances, the addition of Cd... 2+ A DMF solution containing 1-Tb exhibited a significant fluorescence quenching effect at 534 nm. This indicates that the rare earth complex material (1-Tb) enhances the fluorescence quenching effect on Cd. 2+ It exhibits a significant fluorescence quenching effect. This is because one of the carboxyl oxygen groups in the pentafluorobenzoic acid carboxyl group of the Tb rare earth complex material (1-Tb) is not coordinated, and this uncoordinated oxygen reacts with Cd... 2+ This binding process hinders the energy transfer from the lowest excited triplet state T1 to the rare-earth ion, leading to energy transfer from the ligand to Cd. 2+ This promotes fluorescence quenching. Therefore, the above results confirm that the rare earth complex material prepared in this invention can recognize specific Cd... 2+ This leads to the quenching of its fluorescence signal.

[0047] Depend on Figure 3 The results show that rare earth complex materials, as fluorescent probes, are effective against Cd. 2+ The detection limit is as low as 11.24 ppt, and the response time is extremely short, as shown in the results. Figure 4As shown, the maximum quenching efficiency (20%) can be reached within 20 seconds, further confirming that the rare earth complex material prepared by this invention can selectively recognize specific Cd. 2+ The quenching effect that leads to its fluorescence signal can be used as a trace Cd... 2+ The detection uses fluorescent probes and can complete the detection in a short time (20s), with low requirements for detection equipment.

[0048] (3) Interference resistance test of rare earth complex (1-Tb) material, specifically including the following steps:

[0049] Dissolve 5.0 mg of 1-Tb powder in 5.0 mL of LMF solution to obtain a 1-Tb solution. Take 50.0 μL of the 1-Tb solution and add it to 4.9 mL of deionized water, then add 50.0 μL of an equal concentration of Cd. 2+ Solution (1.0×10 -3 M (solvent is deionized water) and 50.0 μL of 19 different interfering ions (Ba) in the same solvent at equal concentrations. 2+ Ca 2+ Co 3+ NH4 + Mg 2+ ,Mn 2+ Cu 2+ ,K + C6H5COO - AlO3 3- SiO3 2- C7H7O3S-,B4O7 2- C6H5O7 3- (C6H5)4B - CH3COO-,WO4 2- SO4 2- SO3 2- The fluorescence performance was tested using a fluorescence spectrometer with an excitation wavelength of 335 nm, and the anti-interference results were obtained as follows: Figure 5 As shown.

[0050] Depend on Figure 5 The results show that the presence of different interfering ions affects Cd. 2+ The test results were not significantly affected, indicating that the rare earth complex material (1-Tb) prepared by this invention has excellent anti-interference performance.

[0051] (4) Using rare earth complex materials to make test strips for Cd 2+ The detection process specifically includes the following steps:

[0052] Cut the filter paper into appropriate sizes (1*1cm) 2The test strips were soaked in a 1-Tb (0.01M) DMF solution for 30 minutes, then dried at 60°C for sensing applications. The dried test strips were then soaked in the aforementioned 20 different ion solutions, with a blank as a control. After drying, they were neatly arranged and photographed under a 365nm UV lamp. The resulting images are shown below. Figure 6 As shown.

[0053] Depend on Figure 6 The results show that, except for soaking in Cd 2+ Except for the test paper in the solution, all the test papers immersed in other ionic solutions emitted Tb. 3+ The unique green luminescence indicates that the rare earth complex material prepared in this invention can be used to make test strips for Cd. 2+ Qualitative detection.

[0054] Although the description of the invention has been quite detailed and particularly of several described embodiments, it is not intended to limit it to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A rare earth complex material used as a test strip and fluorescent probe for the detection of Cd. 2+ Its application in this area is characterized by, The preparation method of the rare earth complex material includes the following steps: first, a rare earth soluble salt and deprotonated rare earth elements 2, 3, 4, 5, 6... The pentafluorobenzoic acid solution was added to the first solvent and mixed well to obtain mixed solution A; the first solvent was water or an organic solvent; then 4,7 dimethyl 1,10 The phenanthroline and the obtained mixed solution A are added to a second solvent to obtain mixed solution B; the second solvent is an organic solvent; finally, the obtained mixed solution B is sealed with pores left, and after the organic solvent has evaporated, the rare earth complex material is obtained. The rare earth soluble salt is any one of nitrate, chloride, acetate, sulfonate, oxalate and trifluoromethanesulfonate, and the rare earth is terbium.

2. The application according to claim 1, characterized in that, 2, 3, 4, 5, 6 (protons removed) The preparation process of pentafluorobenzoic acid solution is as follows: 2, 3, 4, 5, 6 A solution of pentafluorobenzoic acid is dissolved in water, and then the pH is adjusted to 6.0 to obtain deprotonated 2, 3, 4, 5, 6... Pentafluorobenzoic acid solution; 2, 3, 4, 5, 6 The ratio of pentafluorobenzoic acid to water is 10 mg: 1 mL.

3. The application according to claim 2, characterized in that, First solvent, 2, 3, 4, 5, 6 The ratio of pentafluorobenzoic acid to rare earth soluble salt is (2mL) 8mL):10mg:6.7mg.

4. The application according to claim 1, characterized in that, Second solvent and 4,7 dimethyl 1,10 The ratio of phenanthroline was 2 mL: 3.1 mg.

5. The application according to claim 4, characterized in that, The second solvent is dimethyl sulfoxide, N,N At least one of dimethylformamide, tetrahydrofuran, methanol, acetonitrile, ethanol, acetone, acetylacetone, dichloromethane, and trichloromethane.

6. The application according to claim 1, characterized in that, The environmental conditions for the volatilization of organic solvents are any one of the following: conventional atmospheric, nitrogen, oxygen, and argon atmospheres.

7. The application according to claim 6, characterized in that, The organic solvents evaporated under normal atmospheric conditions, with an evaporation time of 20 days. 32 days.

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