A ratiometric fluorescent probe for detection of uranyl ion and a preparation method thereof

Abstract

The application discloses a ratio type fluorescent probe for detecting uranyl ions and a preparation method thereof. The method comprises the following steps: (1) preparing a metal-organic framework material Tb-TPA by taking Tb as a metal center and terephthalic acid (TPA) as an organic ligand; (2) preparing a metal-organic framework material Eu-TMTPA by taking Eu as a metal center and tetramethoxy terephthalic acid (TMTPA) as an organic ligand; and (3) mixing the Tb-TPA and the Eu-TMTPA according to a mass ratio of 1:0.5-3 to obtain the ratio type fluorescent probe. The prepared ratio type fluorescent probe can be used for detecting uranyl ions and has the characteristics of fast response speed, good selectivity and high sensitivity. The probe has a Tb and Eu double emission system, the addition of uranyl ions has no influence on the luminescence of the Tb-TPA, can quench the luminescence of the Eu-TMTPA, thereby realizing ratio type fluorescent analysis, and through self-calibration of two luminescence wave bands, can greatly eliminate or reduce the interference of irrelevant factors of the uranyl ions, and improve the detection sensitivity and accuracy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluorescence detection, and relates to a ratio type fluorescent probe for detecting uranyl ions and a preparation method thereof. BACKGROUND

[0002] With the development of the nuclear industry and the growing demand for nuclear energy, the consumption of uranium continues to grow worldwide. Uranium inevitably flows into the environment at any link from uranium mining to the disposal of radioactive waste. As a heavy metal element, uranium has both radioactivity and chemical toxicity, which not only affects the ecological system, but also enters the human body through drinking water and the food chain, causing diseases of the kidneys, urinary system, and genetics, and threatening human health. Therefore, in the development process of nuclear energy and nuclear technology, the detection and safe and effective disposal of uranium in radioactive waste liquid are important research directions in the environmental field.

[0003] There are various oxidation state forms of uranium in the environment (+2, +3, +4, +5, and +6 valences), and in water bodies, mainly in the form of hexavalent uranyl ions (UO2 2+ ). Currently, the methods for detecting uranyl ions mainly include radioactive measurement, fluorescence, spectrophotometry, inductively coupled plasma-atomic emission spectrometry, ion chromatography, inductively coupled plasma mass spectrometry, and surface-enhanced Raman spectroscopy. Compared with other methods, fluorescence does not require the use of expensive and complex instruments and equipment, is simple and fast to operate, and has good sensitivity and selectivity, and is one of the most important test methods for detecting the concentration of uranyl ions in water bodies.

[0004] In recent years, metal organic framework materials (MOFs) have attracted much attention due to their unique advantages such as porosity, high specific surface area, and adjustable pore channels, and have shown excellent performance in fluorescence sensing, gas storage / separation, and catalysis. Lanthanide elements (such as Tb 3+ , Gd 3+ , and Eu 3+ ) are used as metal center ions to construct lanthanide metal organic framework materials (Ln-MOFs), which have unique fluorescence characteristics due to the existence of the "antenna effect". At present, some Ln-MOFs have been designed for the detection of UO2 2+ , but most of these methods are based on the luminescence intensity of a single luminescence peak for detection, which is easily affected by the external environment, resulting in inaccurate measurement results. However, there are few reports on the use of ratio type metal organic framework fluorescent probes for the detection of uranyl ions.

[0005] The present application aims at the above-mentioned deficiencies of the prior art, and aims to provide a ratio-type fluorescent probe for detection of uranyl ions and a preparation method thereof, which utilizes a Tb and Eu double-emission system, and the addition of uranyl ions has no influence on the luminescence of Tb-TPA, and can quench the luminescence of Eu-TMTPA, so that ratio-type fluorescent analysis is realized, and through self-calibration of two luminescence wave bands, the interference of factors irrelevant to uranyl ions is greatly eliminated or reduced, and the detection sensitivity and accuracy are improved. SUMMARY

[0006] The present application aims at the above-mentioned deficiencies of the prior art, and aims to provide a ratio-type fluorescent probe for detection of uranyl ions and a preparation method thereof, which utilizes a Tb and Eu double-emission system, and the addition of uranyl ions has no influence on the luminescence of Tb-TPA, and can quench the luminescence of Eu-TMTPA, so that ratio-type fluorescent analysis is realized, and through self-calibration of two luminescence wave bands, the interference of factors irrelevant to uranyl ions is greatly eliminated or reduced, and the detection sensitivity and accuracy are improved.

[0007] The ratio-type fluorescent probe for detection of uranyl ions of the present application has a preparation method comprising the following steps:

[0008] (1) preparing a metal-organic framework material Tb-TPA with Tb as a metal center and terephthalic acid TPA as an organic ligand;

[0009] (2) preparing a metal-organic framework material Eu-TMTPA with Eu as a metal center and tetramethoxy terephthalic acid TMTPA as an organic ligand;

[0010] (3) preparing the ratio-type fluorescent probe: mixing Tb-TPA and Eu-TMTPA according to a mass ratio of 1:0.5-3 to obtain the ratio-type fluorescent probe.

[0011] In the above technical solution, further, the preparation of the metal-organic framework material Tb-TPA in (1) specifically comprises: taking terephthalic acid and trivalent terbium salt in a molar ratio of 1:1-3, taking N,N-dimethylformamide DMF and glacial acetic acid, and adding them together into a polytetrafluoroethylene reaction kettle, ultrasonic dispersion, and then placing in a stainless steel outer kettle, and reacting in a constant-temperature box at 110-150 DEG C for 20-50 hours, and after cooling to room temperature, washing the product with DMF and ethanol for multiple times, and then refluxing and exchanging with methanol at 60-100 DEG C for 12-36 hours, and washing with methanol and drying.

[0012] Preferably, the volume ratio of the N,N-dimethylformamide to the glacial acetic acid is 20-50 mL:0.1-0.5 mL.

[0013] Preferably, the trivalent terbium salt is one or more of Tb(NO3)3.6H2O, Tb2(SO4)3.8H2O, Tb2(SO4)3.10H2O and TbCl3.6H2O.

[0014] Further, the preparation of the metal-organic framework material Eu-TMTPA in (2) specifically comprises: taking tetramethoxyl terephthalic acid and trivalent europium salt in a molar ratio of 1:1-3, N,N-dimethylformamide and glacial acetic acid, adding them into a reaction kettle made of polytetrafluoroethylene, placing them in a stainless steel outer kettle after ultrasonic dispersion, and reacting in a thermostat at 110-150 DEG C for 20-50 hours; after cooling to room temperature, washing the product with DMF and ethanol for multiple times, and then refluxing with methanol at 60-100 DEG C for 12-36 hours; after washing with methanol, drying.

[0015] Preferably, the trivalent europium salt is one or more of Eu(NO3)3.6H2O, Eu2(SO4)3.8H2O, Eu2(SO4)3.10H2O and EuCl3.6H2O.

[0016] Preferably, the volume ratio of N,N-dimethylformamide to glacial acetic acid is 20-50 mL:0.1-0.5 mL.

[0017] The above ratio type fluorescent probe or the ratio type fluorescent probe prepared by the above method is applied to the detection of uranyl ions.

[0018] Principles and advantages of the present application:

[0019] Since uranyl ions belong to hard acid, according to the soft-hard acid-base theory, hard base ligands containing oxygen atoms are suitable for coordination with uranyl ions. When the ratio type fluorescent probe acts on uranyl ions, the lone pair electrons in the molecule selectively coordinate with uranyl ions to form uranyl-ligand compounds, so that the stereostructure and electronic distribution of the whole system change, and further cause the change of its fluorescence spectrum. By using the Tb and Eu double emission system, the addition of uranyl ions has no influence on the luminescence of Tb-TPA, and can quench the luminescence of Eu-TMTPA, so that ratio type fluorescent analysis is realized, through the self-calibration of two luminescence wave bands, the interference of factors irrelevant to uranyl ions is greatly eliminated or reduced, and the detection sensitivity and accuracy are improved. The ratio type fluorescent probe also has the advantages of simple method, rapidness, wider linear range, and lower detection limit obtained without any complex equipment. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Selectivity of the ratio type fluorescent probe of Example 1 for uranyl ions;

[0021] Figure 2 Linear relationship between the ratio type fluorescent probe of Example 1 and the concentration of uranyl ions. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be further illustrated below with examples, but these examples do not limit the protection scope of the present application, and various modifications or changes made by those skilled in the art on the basis of the technical solutions of the present application without creative efforts are still within the protection scope of the present application.

[0023] Example 1

[0024] (1) Preparation of metal-organic framework material Tb-TPA: First, terephthalic acid (TPA) and Tb(NO3)3·6H2O were weighed by an electronic balance with a molar ratio of 1:1, 20 mL of N,N-dimethylformamide (DMF) was measured by a measuring cylinder, and 0.2 mL of glacial acetic acid was taken by a pipette. The above medicines were added together into a polytetrafluoroethylene (PTFE) reaction kettle, and ultrasonic dispersion was performed for 15 min. Finally, the reaction kettle was placed into a suitable stainless steel outer kettle, and reaction was performed in a constant temperature box at 130℃ for 36 hours. After the autoclave was cooled to room temperature, the product was washed with DMF and ethanol for several times, and then exchanged with 50 mL of methanol at 80℃ for 24 hours. After washing with methanol, the sample was placed into a drying box at 80℃ for overnight drying.

[0025] (2) Preparation of metal-organic framework material Eu-TMTPA: First, tetramethoxy terephthalic acid (TMTPA) and Eu(NO3)3·6H2O were weighed by an electronic balance with a molar ratio of 1:1, 20 mL of N,N-dimethylformamide (DMF) was measured by a measuring cylinder, and 0.2 mL of glacial acetic acid was taken by a pipette. The above medicines were added together into a polytetrafluoroethylene (PTFE) reaction kettle, and ultrasonic dispersion was performed for 15 min. Finally, the reaction kettle was placed into a suitable stainless steel outer kettle, and reaction was performed in a constant temperature box at 130℃ for 36 hours. After the autoclave was cooled to room temperature, the product was washed with DMF and ethanol for several times, and then exchanged with 50 mL of methanol at 80℃ for 24 hours. After washing with methanol, the sample was placed into a drying box at 80℃ for overnight drying.

[0026] (3) Preparation of the ratio type fluorescent probe: Tb-TPA and Eu-TMTPA were mixed according to a mass ratio of 1:1 to obtain the ratio type fluorescent probe.

[0027] The fluorescence detection performance of the ratio type fluorescent probe was explored. Uranyl ions showed the most obvious fluorescence response effect on the ratio type fluorescent probe. Figure 1 ) In the range of 0-100 μM, the fluorescence emission intensity of the ratio type fluorescent probe had a good linear correlation with the concentration of uranyl ions Figure 2 ), and the detection limit was calculated to be 4.3 μM.

[0028] Example 2

[0029] (1) Preparation of metal-organic framework material Tb-TPA: First, an electronic balance was used to weigh terephthalic acid (TPA) and Tb(NO3)3·6H2O in a molar ratio of 1:1.5, a measuring cylinder was used to measure 20 mL of N,N-dimethylformamide (DMF), and a pipette was used to take 0.2 mL of glacial acetic acid. The above-mentioned drugs were added together into a polytetrafluoroethylene (PTFE) reaction kettle, and ultrasonic dispersion was performed for 15 min. Finally, the reaction kettle was placed into a suitable stainless steel outer kettle, and reaction was performed in a constant-temperature oven at 130°C for 36 hours. After the autoclave cooled to room temperature, the product was washed with DMF and ethanol several times, and then 50 mL of methanol was used to exchange at 80°C for 24 hours. After washing with methanol, the sample was placed in a drying oven at 80°C for overnight drying.

[0030] (2) Preparation of metal-organic framework material Eu-TMTPA: First, an electronic balance was used to weigh terephthalic acid (TPA) and Tb(NO3)3·6H2O in a molar ratio of 1:1.5, a measuring cylinder was used to measure 20 mL of N,N-dimethylformamide (DMF), and a pipette was used to take 0.2 mL of glacial acetic acid. The above-mentioned drugs were added together into a polytetrafluoroethylene (PTFE) reaction kettle, and ultrasonic dispersion was performed for 15 min. Finally, the reaction kettle was placed into a suitable stainless steel outer kettle, and reaction was performed in a constant-temperature oven at 130°C for 36 hours. After the autoclave cooled to room temperature, the product was washed with DMF and ethanol several times, and then 50 mL of methanol was used to exchange at 80°C for 24 hours. After washing with methanol, the sample was placed in a drying oven at 80°C for overnight drying.

[0031] (3) Preparation of a ratio-type fluorescent probe: Tb-TPA and Eu-TMTPA were mixed in a mass ratio of 1:1.5 to obtain a ratio-type fluorescent probe.

[0032] The fluorescence detection performance of the ratio-type fluorescent probe was explored. Uranyl ions showed the most obvious fluorescence response effect on the ratio-type fluorescent probe. In the range of 0-100 μM, the fluorescence intensity of the ratio-type fluorescent probe had a good linear correlation with the concentration of uranyl ions, and the detection limit was calculated to be 6.3 μM.

[0033] Example 3

[0034] (1) Preparation of metal-organic framework material Tb-TPA: First, take the terephthalic acid (TPA) and Tb(NO3)3.6H2O with a molar ratio of 1:2 by electronic balance, use a measuring cylinder to measure 20 mL of N,N-dimethylformamide (DMF), and then use a pipette to take 0.2 mL of glacial acetic acid. Put the above medicines together into a polytetrafluoroethylene (PTFE) reactor, and ultrasonic dispersion for 15 min. Finally, place the reactor into a suitable stainless steel outer reactor, and react in a constant temperature oven at 130℃ for 36 hours. After the autoclave is cooled to room temperature, the product is washed with DMF and ethanol several times, and then exchanged with 50 mL of methanol at 80℃ for 24 hours. After washing with methanol, the sample is placed in a drying oven at 80℃ overnight.

[0035] (2) Preparation of metal-organic framework material Eu-TMTPA: First, take the tetramethoxy terephthalic acid (TMTPA) and Eu(NO3)3.6H2O with a molar ratio of 1:2 by electronic balance, use a measuring cylinder to measure 20 mL of N,N-dimethylformamide (DMF), and then use a pipette to take 0.2 mL of glacial acetic acid. Put the above medicines together into a polytetrafluoroethylene (PTFE) reactor, and ultrasonic dispersion for 15 min. Finally, place the reactor into a suitable stainless steel outer reactor, and react in a constant temperature oven at 130℃ for 36 hours. After the autoclave is cooled to room temperature, the product is washed with DMF and ethanol several times, and then exchanged with 50 mL of methanol at 80℃ for 24 hours. After washing with methanol, the sample is placed in a drying oven at 80℃ overnight.

[0036] (3) Preparation of the ratio type fluorescent probe: Mix Tb-TPA and Eu-TMTPA according to a mass ratio of 1:2 to obtain the ratio type fluorescent probe.

[0037] The fluorescence detection performance of the ratio type fluorescent probe was explored. Uranyl ions showed the most obvious fluorescence response effect on the ratio type fluorescent probe. In the range of 0-100 μM, the fluorescence emission intensity of the ratio type fluorescent probe had a good linear correlation with the concentration of uranyl ions, and the detection limit was calculated to be 8.3 μM.

[0038] The above is only a preferred embodiment of the present application, and is not intended to limit the other forms of the present application. Any skilled person in the art can use the above disclosed technical content to make changes or modifications into equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments still belong to the protection scope of the technical solution of the present application.

Claims

1. A method for preparing a ratiometric fluorescent probe for uranyl ion detection, characterized in that, Includes the following steps: (1) Using Tb as the metal center and terephthalic acid (TPA) as the organic ligand, a metal-organic framework material Tb-TPA was prepared; (2) Using Eu as the metal center and tetramethoxyterephthalic acid (TMTPA) as the organic ligand, a metal-organic framework material Eu-TMTPA was prepared. (3) Tb-TPA and Eu-TMTPA are mixed at a mass ratio of 1:0.5 to 3 to obtain a ratiometric fluorescent probe for uranyl ion detection.

2. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 1, characterized in that, The preparation of the metal-organic framework material Tb-TPA in (1) specifically includes: taking terephthalic acid and trivalent terbium salt in a molar ratio of 1:1 to 3, taking N,N-dimethylformamide (DMF) and glacial acetic acid, and adding them together into a polytetrafluoroethylene reaction vessel. After ultrasonic dispersion, the mixture is placed in a stainless steel outer vessel and reacted in a constant temperature oven at 110 to 150°C for 20 to 50 hours. After cooling to room temperature, the product is washed multiple times with DMF and ethanol, and then refluxed with methanol at 60 to 100°C for 12 to 36 hours. After washing with methanol, the product is dried.

3. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 2, characterized in that, The volume ratio of N,N-dimethylformamide to glacial acetic acid is 20-50 mL: 0.1-0.5 mL.

4. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 2, characterized in that, The trivalent terbium salt is one or more of Tb(NO3)3·6H2O, Tb2(SO4)3·8H2O, Tb2(SO4)3·10H2O, and TbCl3·6H2O.

5. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 1, characterized in that, The preparation of the metal-organic framework material Eu-TMTPA in (2) specifically includes: taking tetramethoxyterephthalic acid and trivalent europium salt in a molar ratio of 1:1 to 3, taking N,N-dimethylformamide and glacial acetic acid, and adding them together into a polytetrafluoroethylene reaction vessel. After ultrasonic dispersion, the mixture is placed in a stainless steel outer vessel and reacted in a constant temperature oven at 110 to 150°C for 20 to 50 hours. After cooling to room temperature, the product is washed multiple times with DMF and ethanol, and then refluxed with methanol at 60 to 100°C for 12 to 36 hours. After washing with methanol, the product is dried.

6. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 5, characterized in that, The trivalent europium salt is one or more of Eu(NO3)3·6H2O, Eu2(SO4)3·8H2O, Eu2(SO4)3·10H2O, and EuCl3·6H2O.

7. The method for preparing the ratiometric fluorescent probe for uranyl ion detection according to claim 5, characterized in that, The volume ratio of N,N-dimethylformamide to glacial acetic acid is 20-50 mL: 0.1-0.5 mL.

8. A ratiometric fluorescent probe, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The use of the ratiometric fluorescent probe as described in claim 8, characterized in that, This probe is used to detect uranyl ions.

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