Eu-MOF ratiometric fluorescent probe as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of fluorescent probe detection, and particularly relates to an Eu-MOF ratiometric fluorescent probe as well as a preparation method and application thereof. The preparation method of the Eu-MOF ratiometric fluorescent probe comprises the following steps: adding a europium acetate solution into a 2-aminoterephthalic acid solution, standing, washing and drying to obtain the Eu-MOF ratiometric fluorescent probe. The Eu-MOF dual-emission-ratio fluorescent probe prepared by the invention has high sensitivity and accuracy, and can perform specific recognition on formaldehyde in the presence of interfering substances. Moreover, the ratiometric fluorescent probe disclosed by the invention is simple to synthesize and easy to produce, the whole detection process is convenient and rapid, as the concentration of the formaldehyde is increased, the amino is used as a recognition group and is subjected to a Schiff base reaction with the formaldehyde, the PET process is inhibited, the ligand fluorescence is enhanced, and the process that the solution gradually changes from red to blue can be clearly observed under an ultraviolet lamp.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent probe detection, and specifically relates to a Eu-MOF ratio fluorescent probe and a preparation method and application thereof. Background Art

[0002] Formaldehyde (FA) is a common organic compound with high reactivity and high water solubility. It is widely used in chemical industries such as wood processing, drug synthesis, and textiles. Formaldehyde is also an important carbonyl compound in biological metabolism and can prolong the shelf life of fruits and vegetables, but illegal addition or improper storage can lead to serious environmental pollution and human health problems. Formaldehyde has a destructive effect on biological cell proteins and is a highly toxic cytoplasm. The International Agency for Research on Cancer (IARC) has listed it as a carcinogen. However, formaldehyde is a colorless gas that is not easily detected at low concentrations and can be easily masked by other odors. However, low doses of formaldehyde can cause headaches, pharyngitis, allergic pneumonia, skin allergies, and breathing difficulties. At the same time, high concentrations of formaldehyde can lead to neurodegenerative diseases, chronic liver disease, and other serious organ damage, and even death. Therefore, the development of a highly sensitive and accurate probe molecule for the detection of formaldehyde is crucial to the ecological environment and human health.

[0003] Formaldehyde detection methods include colorimetry, high performance liquid chromatography, gas chromatography, electrochemical method, etc., but these traditional detection methods are complicated to operate, expensive equipment and long detection time, which limits their practical application. Fluorescent probes have the advantages of unique non-destructive in-situ analysis capabilities, simple operation, high sensitivity, real-time visualization, etc., and have broad application prospects. However, most of these fluorescent probe sensors come from a single emission. This fluorescence method based on the absolute intensity of a single emission is easily affected by instruments, environmental conditions and probe concentration, resulting in inaccurate measurements. Compared with the fluorescence spectrum of a single emission, the ratio fluorescence probe can effectively solve the above problems because it can achieve internal self-calibration by recording the ratio of the fluorescence intensity of two wavelengths in the system to overcome signal fluctuations and provide more accurate and reliable information. In particular, a dual-emission ratio fluorescence probe with one emission intensity reduced and the other emission intensity reversely increased has higher sensitivity and accuracy due to inherent signal amplification. Therefore, it is necessary to establish a simple ratio fluorescence probe to detect formaldehyde. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing a Eu-MOF ratio fluorescent probe. The ratio fluorescent probe of the present invention is simple to synthesize and easy to produce.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The preparation method of the above-mentioned Eu-MOF ratio fluorescent probe comprises the following steps:

[0007] The europium acetate solution was added to the 2-aminoterephthalic acid solution, and the Eu-MOF ratio fluorescence probe was obtained after standing, washing and drying.

[0008] Preferably, the concentration of the europium acetate solution is 10-20 mmol / L, and the concentration of the 2-aminoterephthalic acid solution is 20 mmol / L.

[0009] Preferably, the solvent of the europium acetate solution and the 2-aminoterephthalic acid solution is a mixture of N,N-dimethylformamide, ethanol and water in a volume ratio of 15:1:1.

[0010] Preferably, the volume ratio of the europium acetate solution to the 2-aminoterephthalic acid solution is 1:(1-3).

[0011] More preferably, in step (3), the volume ratio of the europium acetate solution to the 2-aminoterephthalic acid solution is 1:1.

[0012] Preferably, the europium acetate solution is added to the 2-aminoterephthalic acid solution by dropwise addition at a speed of 0.2-0.6 μL / s.

[0013] More preferably, the standing time is 24 hours.

[0014] More preferably, the washing is first washing with N,N-dimethylformamide and then washing with ethanol.

[0015] A second object of the present invention is to provide a Eu-MOF ratio fluorescence probe.

[0016] To achieve the above object, the present invention adopts the following technical solutions:

[0017] A Eu-MOF ratio fluorescent probe is prepared by adopting the above preparation method.

[0018] The chemical formula of the probe prepared in the present invention is {[Eu(C 8 H 5 NO 4 ) 1.5 (DMF) 2 ]·2H 2 O·DMF}n, where n is an integer greater than 1, referred to as Eu-MOF; where C 8 H 5 NO 4 2-It is obtained by deprotonation of the ligand 2-aminoterephthalic acid, and DMF is N,N-dimethylformamide. The obtained Eu-MOF ratio fluorescence probe crystal belongs to the triclinic system, the space group is P-1, and the unit cell parameters are: α=104.553(5), b=109.857(4), γ=95.438(5). The asymmetric unit of the Eu-MOF material contains a crystallographically independent Eu 3+ , 1.5 independent C 8 H 5 NO 4 2- ions and 2 DMF, among which there are also 2 free water molecules and 1 free DMF molecule.

[0019] The third object of the present invention is to provide an application of a Eu-MOF ratio fluorescence probe in the detection of formaldehyde, which can detect formaldehyde with high sensitivity and high selectivity. Moreover, the entire detection process is convenient and fast, and visual detection can be achieved.

[0020] Preferably, the application of the Eu-MOF ratio fluorescent probe in the detection of formaldehyde comprises the following steps: grinding the Eu-MOF ratio fluorescent probe and ultrasonically dispersing it in DMF to prepare a Eu-MOF suspension, adding a substance to be detected thereto to obtain a sample solution to be tested, and testing its fluorescence spectrum.

[0021] Preferably, the above detection method specifically comprises the following steps:

[0022] The Eu-MOF ratio fluorescence probe was ground and ultrasonically dispersed in DMF to prepare a Eu-MOF suspension, to which formaldehyde was added to prepare formaldehyde sample solutions of different concentrations; its fluorescence spectrum was tested, and the ratio of the fluorescence intensity at wavelengths of 430 nm and 617 nm was calculated. 430 / I 617 The relationship between the fluorescence intensity ratio and the formaldehyde concentration was obtained, and the standard curve of the fluorescence intensity ratio and the formaldehyde concentration was obtained; the substance to be tested was added to the Eu-MOF suspension to obtain the sample solution to be tested, the fluorescence spectrum was tested, and I 430 / I 617 , and the formaldehyde content in the substance to be tested is calculated based on the standard curve.

[0023] Preferably, the Eu-MOF ratio fluorescent probe is ground into 60-80 mesh, and the concentration of the Eu-MOF suspension is 0.1 mg / mL.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a Eu-MOF ratio fluorescent probe, wherein the amino-functionalized Eu-MOF has Eu 3+The dual emission peaks of the organic ligand (λ=617nm) and the organic ligand (λ=430nm) can realize internal self-calibration through the ratio of the fluorescence intensity of the two wavelengths in the system to overcome signal fluctuations and provide more accurate and reliable information. The amino group in the Eu-MOF prepared by the present invention does not participate in the coordination. The amino group, as an electron-donating group, produces a photoinduced electron effect (PET) on the fluorophore to quench the fluorescence. As the concentration of formaldehyde increases, the amino group, as a recognition group, reacts with formaldehyde to produce a Schiff base. The amino group and formaldehyde react to form azomethine, the energy level changes, the PET process is inhibited, and the fluorescence is enhanced. The process of the solution gradually changing from red to blue can be clearly observed under ultraviolet light. The dual-emission ratio fluorescent probe prepared by the present invention has high sensitivity and accuracy, and can specifically identify formaldehyde in the presence of interfering substances.

[0026] 2. The present invention provides a method for preparing the above-mentioned Eu-MOF ratio fluorescent probe. The ratio fluorescent probe of the present invention is simple to synthesize and easy to produce. The amino group in the Eu-MOF ratio fluorescent probe is not coordinated with the metal europium ion, and an amino-functionalized Eu-MOF ratio fluorescent probe is prepared.

[0027] 3. The present invention provides the use of the above-mentioned Eu-MOF ratio fluorescence probe in the detection of formaldehyde. It can detect formaldehyde with high sensitivity and high selectivity, and the whole detection process is convenient and fast, and visual detection can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a crystal structure diagram of the Eu-MOF ratio fluorescence probe of the present invention; wherein, Figure 1 (a) Diagram of the connection between metal ions and organic ligands. Figure 1 (b) is a three-dimensional crystal structure diagram;

[0029] Figure 2 is the powder diffraction pattern of the Eu-MOF ratio fluorescent probe of the present invention;

[0030] Figure 3 This is a microscope image of the Eu-MOF ratio fluorescence probe of the present invention;

[0031] Figure 4 This is a thermogravimetric curve of the Eu-MOF ratio fluorescence probe of the present invention;

[0032] Figure 5 It is the fluorescence spectrum of the Eu-MOF ratio fluorescence probe of the present invention;

[0033] Figure 6 The fluorescence spectra of Eu-MOF after adding different concentrations of formaldehyde;

[0034] Figure 7 is the fluorescence intensity ratio of Eu-MOF (I430nm / I 617 nm ) and formaldehyde concentration;

[0035] Figure 8 Optical photos of filter paper loaded with Eu-MOF under ultraviolet light after adding different concentrations of formaldehyde;

[0036] Fig. 9 The fluorescence intensity stability of the Eu-MOF ratiometric fluorescence probe for formaldehyde detection within 1 week. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further explained below in conjunction with specific embodiments, test examples and drawings.

[0038] In the following examples and test examples, the raw materials and preparation methods used are conventional materials and techniques in the art unless otherwise specified.

[0039] Example 1

[0040] This embodiment provides a method for preparing a Eu-MOF ratio fluorescence probe, comprising the following steps:

[0041] (1) Europium acetate hydrate ([Eu(OOCCH 3 )·3H 2 O]) was dissolved in a mixture of N,N-dimethylformamide (DMF) (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to prepare a europium (III) acetate solution;

[0042] (2) Then (61.6 mg, 0.34 mmol) of 2-aminoterephthalic acid was dissolved in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to obtain a 2-aminoterephthalic acid solution;

[0043] (3) Add 1 mL of deionized water to 3 mL of the 2-aminoterephthalic acid solution in step (2), transfer to a glass culture dish, and then slowly add 3 mL of the europium acetate solution obtained in step (1) to the glass culture dish containing the 2-aminoterephthalic acid solution at a rate of 0.2 μL / s, shaking while adding, and let stand at room temperature for 24 hours, first wash with DMF 3 times, then wash with ethanol 3 times, filter and dry naturally in air to obtain the Eu-MOF ratio fluorescent probe.

[0044] This embodiment 1 also provides a Eu-MOF ratio fluorescent probe, which is prepared using the above preparation method.

[0045] Example 2

[0046] This embodiment provides a method for preparing a Eu-MOF ratio fluorescence probe, comprising the following steps:

[0047] (1) Europium acetate hydrate ([Eu(OOCCH 3 )·3H 2 O]) was dissolved in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to prepare a europium (III) acetate solution;

[0048] (2) Then (61.6 mg, 0.34 mmol) of 2-aminoterephthalic acid was dissolved in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to obtain a 2-aminoterephthalic acid solution;

[0049] (3) Add 1 mL of deionized water to 6 mL of 2-aminoterephthalic acid solution in step (2), transfer to a glass culture dish, then slowly add 3 mL of the europium acetate solution obtained in step (1) to the glass culture dish containing the 2-aminoterephthalic acid solution at a rate of 0.4 μL / s, shake while adding, let stand at room temperature for 24 hours, first wash with DMF 3 times, then wash with ethanol 3 times, filter and dry naturally in air to obtain the Eu-MOF ratio fluorescent probe.

[0050] This embodiment 2 also provides a Eu-MOF ratio fluorescent probe, which is prepared using the above preparation method.

[0051] Example 3

[0052] This embodiment provides a method for preparing a Eu-MOF ratio fluorescence probe, comprising the following steps:

[0053] (1) Europium acetate hydrate ([Eu(OOCCH 3 )·3H 2 O]) was dissolved in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to prepare a europium (III) acetate solution;

[0054] (2) Then (61.6 mg, 0.34 mmol) of 2-aminoterephthalic acid was dissolved in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), and stirred at room temperature to obtain a 2-aminoterephthalic acid solution;

[0055] (3) Add 1 mL of deionized water to 3 mL of the 2-aminoterephthalic acid solution in step (2), transfer to a glass culture dish, and then slowly add 3 mL of the europium acetate solution obtained in step (1) to the glass culture dish containing the 2-aminoterephthalic acid solution at a rate of 0.6 μL / s, shaking while adding, and let stand at room temperature for 24 hours, first wash with DMF 3 times, then wash with ethanol 3 times, filter and dry naturally in air to obtain the Eu-MOF ratio fluorescent probe.

[0056] This embodiment 3 also provides a Eu-MOF ratio fluorescent probe, which is prepared using the above preparation method.

[0057] Test Example 1

[0058] The single crystal structure of the product obtained in Example 1 is as follows Figure 1 shown. Figure 1 (a) Diagram of the connection between metal ions and organic ligands. Figure 1 (b) is a three-dimensional crystal structure diagram. The crystal structure of the Eu-MOF ratio fluorescence probe in Example 1 was tested using an X-ray single crystal diffractometer. The results are as follows: Figure 2 shown.

[0059] Depend on Figure 2 The powder diffraction pattern (PXRD) test results show that the powder diffraction results measured in Example 1 are basically consistent with the single crystal structure simulation results, that is, the product obtained in the present invention has a high purity. The chemical formula of the probe prepared in the present invention is {[Eu(C 8 H 5 NO 4 ) 1.5 (DMF) 2 ]·2H 2 O·DMF}n, where n is an integer greater than 1, referred to as Eu-MOF; where C 8 H 5 NO 4 2- It is obtained by deprotonation of the ligand 2-aminoterephthalic acid, and DMF is N,N-dimethylformamide. The obtained Eu-MOF ratio fluorescence probe crystal belongs to the triclinic system, the space group is P-1, and the unit cell parameters are: α=104.553(5), b=109.857(4), γ=95.438(5). The asymmetric unit of the Eu-MOF material contains a crystallographically independent Eu 3+ , 1.5 independent C 8 H 5 NO 4 2- ions and 2 DMF, among which there are also 2 free water molecules and 1 free DMF molecule.

[0060] Test Example 2

[0061] Figure 3 This is a microscope photo of the Eu-MOF material of the present invention. It can be seen that Eu-MOF is a block crystal with a size of about 0.18 μm and uniform size.

[0062] Test Example 3

[0063] Figure 4 This is the thermogravimetric curve of the Eu-MOF material of the present invention. It can be seen that at around 160°C, Eu-MOF begins to lose weight. In the first stage from 160 to 230°C, the weight loss is approximately 18.1% (theoretical value is 16.1%), which is mainly due to the free water molecules and DMF molecules in Eu-MOF. In the second stage from 230 to 580°C, the weight loss is approximately 22.2% (theoretical value is 21.6%), which is mainly due to the coordinated DMF molecules in Eu-MOF. After that, the remaining structure begins to decompose, indicating that the main skeleton structure of the Eu-MOF ratio fluorescent probe has good thermal stability.

[0064] Test Example 4

[0065] The application of the above-mentioned Eu-MOF ratio fluorescent probe in the detection of formaldehyde comprises the following steps: grinding the obtained Eu-MOF ratio fluorescent probe for 40 minutes, dispersing 10 mg of the ground Eu-MOF in 100 mL of DMF, treating with ultrasound (ultrasound power of 60-70 Hz) for 40 minutes to prepare a Eu-MOF suspension with good dispersion and stability, and then taking 3 mL of the Eu-MOF suspension and adding it to a cuvette, and testing its fluorescence spectrum by a fluorescence spectrometer. The results are as follows: Figure 5 As shown. Figure 5 It can be seen from the excitation spectrum and emission spectrum that Eu-MOF has dual emission peaks at λ = 430nm (blue light) and λ = 617nm (red light), which provides a good platform for ratiometric fluorescence detection of formaldehyde.

[0066] Different concentrations of formaldehyde (2, 4, 6, 8, 10, 14, 18, 20, 24, 28, 30, 40, 50, 60, 70, 80, 90, 100 μM) were added to the Eu-MOF suspension. The fluorescence spectrum of the Eu-MOF suspension was tested by a fluorescence spectrometer under the excitation of 365 nm. The results are as follows: Figure 6 As shown; the relationship between the ratio of fluorescence intensity at 430nm and 617nm and the formaldehyde concentration was calculated, and the results are as follows Figure 7 shown.

[0067] Depend on Figure 6From the fluorescence spectra of the solutions after adding formaldehyde of different concentrations, we can see that after adding formaldehyde of different concentrations (2, 4, 6, 8, 10, 14, 18, 20, 24, 28, 30, 40, 50, 60, 70, 80, 90, 100 μM), the fluorescence spectra changed to varying degrees. It can be observed that with the increase of formaldehyde concentration, the fluorescence intensity at a wavelength of 430 nm gradually increased, and the fluorescence intensity at a wavelength of 617 nm decreased slightly.

[0068] Figure 7 is the ratio of the fluorescence intensity at λ = 430 nm to that at λ = 617 nm (I 430 / I 617 ) and formaldehyde concentration, and thus the correlation coefficient between the fluorescence intensity ratio and the formaldehyde concentration was obtained. The results showed that the fluorescence intensity ratio (I 430 / I 617 ) is linearly related to the formaldehyde concentration of 0-30 μM, indicating that the Eu-MOF ratio fluorescence probe can quantitatively detect lower concentrations of formaldehyde.

[0069] Figure 8 The filter paper was used as a self-supporting membrane, and the filter paper was immersed in the Eu-MOF suspension, ultrasonically dispersed, and naturally dried in air. The Eu-MOF probe-loaded membrane was obtained. The probe-loaded film was exposed to formaldehyde solutions of different concentrations (10μM, 20μM, 30μM, 40μM, 50μM, 60μM, 70μM, 80μM, 90μM, 100μM, 200μM, 400μM, 1000μM). Under ultraviolet irradiation, its color can be visually observed to change from red to blue, indicating that the probe can detect formaldehyde with high sensitivity and selectivity, and realize visual detection.

[0070] Fig. 9 The relative intensity change of the fluorescence spectrum of the Eu-MOF material of the present invention when used as a ratio fluorescence probe to detect formaldehyde within a storage time of 1 week is shown in FIG. Fig. 9 It can be seen that the Eu-MOF fluorescence ratio probe of the present invention exhibits good stability when detecting formaldehyde concentration.

[0071] The above are only preferred embodiments of the present invention, and are not limited to the above examples. For those skilled in the art, various changes and variations are possible under the principle of the present invention. Any modifications and improvements made should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a Eu-MOF ratio fluorescent probe, characterized in that: The steps include: The europium acetate solution was added to the 2-aminoterephthalic acid solution, and the Eu-MOF ratio fluorescence probe was obtained after standing, washing and drying.

2. The method for preparing a Eu-MOF ratio fluorescent probe according to claim 1, characterized in that: The concentration of the europium acetate solution is 10-20 mmol / L, and the concentration of the 2-aminoterephthalic acid solution is 20 mmol / L.

3. The method for preparing a Eu-MOF ratio fluorescent probe according to claim 1, characterized in that: The solvents of the europium acetate solution and the 2-aminoterephthalic acid solution are obtained by mixing N,N-dimethylformamide, ethanol and water in a volume ratio of 15:1:

1.

4. The method for preparing a Eu-MOF ratio fluorescent probe according to claim 1, characterized in that: The volume ratio of the europium acetate solution to the 2-aminoterephthalic acid solution is 1:(1-3).

5. The method for preparing a Eu-MOF ratio fluorescent probe according to claim 1, characterized in that: The europium acetate solution is added to the 2-aminoterephthalic acid solution by dropwise addition at a speed of 0.2-0.6 μL / s.

6. A Eu-MOF ratio fluorescence probe, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the Eu-MOF ratio fluorescent probe as claimed in claim 6 in detecting formaldehyde.

8. The use of the Eu-MOF ratio fluorescence probe in detecting formaldehyde according to claim 7, characterized in that: The method comprises the following steps: grinding the Eu-MOF ratio fluorescent probe and then ultrasonically dispersing it in DMF to prepare a Eu-MOF suspension, adding a substance to be tested to obtain a sample solution to be tested, and testing its fluorescence spectrum.

9. The use of the Eu-MOF ratio fluorescence probe in detecting formaldehyde according to claim 8, characterized in that: The above detection method specifically comprises the following steps: grinding the Eu-MOF ratio fluorescence probe and ultrasonically dispersing it in DMF to prepare a Eu-MOF suspension, adding formaldehyde thereto, and preparing formaldehyde sample solutions of different concentrations; testing its fluorescence spectrum, and calculating the ratio of the fluorescence intensity at wavelengths of 430 nm and 617 nm. 430 / I 617 The relationship between the fluorescence intensity ratio and the formaldehyde concentration was obtained to obtain a standard curve of the fluorescence intensity ratio and the formaldehyde concentration; The substance to be tested is added into the Eu-MOF suspension to obtain the sample solution to be tested, the fluorescence spectrum is tested, and I is calculated. 430 / I 617 , and the formaldehyde content in the substance to be tested is calculated based on the standard curve.

10. Use of the Eu-MOF ratio fluorescence probe according to claim 8 or 9 in detecting formaldehyde, characterized in that: The Eu-MOF ratio fluorescent probe was ground into 60-80 meshes, and the concentration of the Eu-MOF suspension was 0.1 mg / mL.

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