Eu-mof ratio fluorescent probe, preparation method and application thereof

Abstract

The application belongs to the technical field of fluorescent probe detection, and particularly relates to a Eu-MOF ratio fluorescent probe and a preparation method and application thereof. The preparation method of the Eu-MOF ratio fluorescent probe comprises the following steps: adding a europium acetate solution into a 2-amino terephthalic acid solution, and obtaining the Eu-MOF ratio fluorescent probe after standing, washing and drying. The Eu-MOF double-emission ratio fluorescent probe prepared by the application has high sensitivity and accuracy, and can specifically recognize formaldehyde in the presence of interfering substances. Moreover, the ratio fluorescent probe of the application is simple to synthesize and easy to produce, and the whole detection process is convenient and fast. With the increase of the formaldehyde concentration, the amino group as the recognition group reacts with formaldehyde to form a Schiff base, inhibits the PET process, enhances the ligand fluorescence, and the solution gradually changes from red to blue under the ultraviolet lamp.

Description

TECHNICAL FIELD

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

[0002] Formaldehyde (FA) is a common organic compound with high reactivity and high water solubility, and is widely used in the chemical industry such as wood processing, drug synthesis, and textile. Formaldehyde is also an important carbonyl compound in the biological metabolic process, which can prolong the shelf life of fruits and vegetables, but illegal addition or improper storage can cause serious environmental pollution and human health problems. Formaldehyde has a destructive effect on biological cell proteins and is a highly toxic cytoplasm, which has been listed as one of the carcinogens by the International Agency for Research on Cancer (IARC). However, formaldehyde is a colorless gas, which is not easy to detect at low concentrations and can be easily masked by other odors. However, low-dose formaldehyde can cause headaches, throat inflammation, allergic pneumonitis, skin allergies, and breathing difficulties. At the same time, high concentrations of formaldehyde can cause neurodegenerative diseases, chronic liver disease and other serious organ damage, and even death. Therefore, it is essential to develop a highly sensitive and accurate probe molecule for detecting formaldehyde for the ecological environment and human health.

[0003] Formaldehyde detection methods include colorimetric method, high performance liquid chromatography, gas chromatography, electrochemical method, etc. However, these traditional detection methods have complex operation, expensive equipment and long detection time, which limits their practical application. Fluorescent probes have unique non-destructive in-situ analysis capabilities, simple operation, high sensitivity, real-time visualization and other advantages, and have wide application prospects. However, most of these fluorescent probe sensors come from single emission, and this single emission-based absolute intensity fluorescence method is easily affected by instruments, environmental conditions and probe concentration, resulting in inaccurate measurement. Compared with single emission fluorescence spectrum, ratio fluorescent probes can effectively solve the above problems, because they can realize internal self-calibration by recording the ratio of the fluorescence intensity at two wavelengths in the system to overcome signal fluctuations and provide more accurate and reliable information. In particular, a dual-emission ratio fluorescent probe with one emission intensity decreasing and the other emission intensity increasing in the opposite direction has higher sensitivity and accuracy due to inherent signal amplification. Therefore, it is necessary to establish a simple ratio fluorescent probe for detecting formaldehyde. SUMMARY

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

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

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

[0007] The Eu-MOF ratio fluorescent probe is obtained by adding the europium acetate solution into the 2-amino terephthalic acid solution, standing, washing and drying.

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

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

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

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

[0012] Preferably, the europium acetate solution is added into the 2-amino terephthalic acid solution in a dropwise manner, and the dropwise adding speed is 0.2-0.6 μL / s.

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

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

[0015] The second object of the present application is to provide a Eu-MOF ratio fluorescent probe.

[0016] To achieve the above object, the present application adopts the following technical scheme:

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

[0018] The chemical formula of the prepared probe is {[Eu(C8H5NO4 1.5 (DMF)2]·2H2O·DMF}n, wherein n is an integer greater than 1, and the Eu-MOF is abbreviated as Eu-MOF; wherein C8H5NO4 2- is a ligand obtained by deprotonation of 2-amino terephthalic acid, and DMF is N,N-dimethylformamide. The obtained Eu-MOF ratio fluorescent probe crystal belongs to a triclinic system, the space group is P-1, and the cell parameters are: a = 104.553(5), b = 109.857(4), g = 95.438(5). The asymmetric unit of the Eu-MOF material contains 1 crystallographically independent Eu 3+ , 1.5 independent C8H5NO4 2- ions and 2 DMF, in addition to 2 free water molecules and 1 free DMF molecule.

[0019] The third object of the present application is to provide an application of the Eu-MOF ratiometric fluorescent probe in detecting formaldehyde, which can detect formaldehyde with high sensitivity and selectivity. Moreover, the whole detection process is convenient and fast, and visual detection can be realized.

[0020] Preferably, the application of the Eu-MOF ratiometric fluorescent probe in detecting formaldehyde comprises the following steps: grinding the Eu-MOF ratiometric fluorescent probe and ultrasonic dispersion in DMF to prepare an Eu-MOF suspension, adding a to-be-detected substance to obtain a to-be-detected sample solution, and testing the fluorescence spectrum.

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

[0022] Grinding the Eu-MOF ratiometric fluorescent probe and ultrasonic dispersion in DMF to prepare an Eu-MOF suspension, adding formaldehyde to prepare formaldehyde sample solutions with different concentrations; testing the fluorescence spectrum, calculating the ratio I 430 / I 617 of the fluorescence intensity at wavelengths of 430 nm and 617 nm, obtaining a standard curve of the fluorescence intensity ratio and the formaldehyde concentration; adding a to-be-detected substance to the Eu-MOF suspension to obtain a to-be-detected sample solution, testing the fluorescence spectrum, and calculating I 430 / I 617 , according to the standard curve to obtain the formaldehyde content in the to-be-detected substance.

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

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

[0025] 1. The present application provides a Eu-MOF ratiometric fluorescent probe, and the amino-functionalized Eu-MOF has Eu 3+The dual emission peaks of (lambda=617nm) and organic ligand (lambda=430nm) can realize internal self-calibration by the ratio of fluorescence intensity at two wavelengths in the system to overcome signal fluctuation and provide more accurate and reliable information. In the Eu-MOF prepared by the application, the amino group does not participate in coordination, and the amino group as an electron-donating group produces a photo-induced electron effect (PET) on the fluorophore to quench fluorescence. With the increase of formaldehyde concentration, the amino group as a recognition group reacts with formaldehyde to form a Schiff base, and the energy level changes to inhibit the PET process, so that the fluorescence is enhanced. Under the ultraviolet lamp, the process of the solution changing from red to blue can be clearly observed. The dual-emission ratio fluorescent probe prepared by the application has high sensitivity and accuracy, and can specifically recognize formaldehyde in the presence of interfering substances.

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

[0027] 3. The application provides the application of the above-mentioned Eu-MOF ratio fluorescent probe in detecting formaldehyde. The Eu-MOF ratio fluorescent probe can detect formaldehyde with high sensitivity and selectivity, and the whole detection process is convenient and fast, and visual detection can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 which is a crystal structure diagram of the Eu-MOF ratio fluorescent probe of the application; Figure 1 (a) is a connection diagram of metal ions and organic ligands, Figure 1 (b) is a three-dimensional crystal structure diagram;

[0029] Figure 2 which is a powder diffraction diagram of the Eu-MOF ratio fluorescent probe of the application;

[0030] Figure 3 which is a microscope diagram of the Eu-MOF ratio fluorescent probe of the application;

[0031] Figure 4 which is a thermogravimetric curve diagram of the Eu-MOF ratio fluorescent probe of the application;

[0032] Figure 5 which is a fluorescence spectrum diagram of the Eu-MOF ratio fluorescent probe of the application;

[0033] Figure 6 which is a fluorescence spectrum diagram of the Eu-MOF after adding formaldehyde with different concentrations;

[0034] Figure 7 which is a fluorescence intensity ratio (I430nm / I 617 nm )with formaldehyde concentration relationship diagram;

[0035] Figure 8 optical photograph of Eu-MOF loaded on filter paper under ultraviolet light after adding different concentrations of formaldehyde;

[0036] Figure 9 fluorescence intensity stability diagram of Eu-MOF ratio fluorescent probe for detecting formaldehyde within 1 week. DETAILED DESCRIPTION

[0037] The technical solutions of the present application are further explained in the following specific examples, 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] The present example provides a preparation method of Eu-MOF ratio fluorescent probe, comprising the following steps:

[0041] (1) Dissolve europium acetate hydrate ([Eu(OOCCH3)·3H2O]) (111.89 mg, 0.34 mmol) in a mixture of N,N-dimethylformamide (DMF) (15 mL), ethanol (1 mL) and water (1 mL), stir uniformly at room temperature, and prepare europium acetate (III) solution;

[0042] (2) Then dissolve 2-amino terephthalic acid (61.6 mg, 0.34 mmol) in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), stir uniformly at room temperature, and prepare 2-amino terephthalic acid solution;

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

[0044] The present example 1 also provides a Eu-MOF ratio fluorescent probe, which is prepared by the above preparation method.

[0045] Example 2

[0046] The embodiment provides a preparation method of a Eu-MOF ratio fluorescent probe, and comprises the following steps:

[0047] (1) Dissolve (55.947 mg, 0.17 mmol) of europium acetate hydrate ([Eu(OOCCH3) 3H2O]) in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), uniformly stir at room temperature, and prepare a europium (III) acetate solution;

[0048] (2) Then dissolve (61.6 mg, 0.34 mmol) of 2-amino terephthalic acid in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), uniformly stir at room temperature, and prepare a 2-amino terephthalic acid solution;

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

[0050] The embodiment 2 further provides a Eu-MOF ratio fluorescent probe, which is prepared by using the preparation method.

[0051] Embodiment 3

[0052] The embodiment provides a preparation method of a Eu-MOF ratio fluorescent probe, and comprises the following steps:

[0053] (1) Dissolve (55.947 mg, 0.17 mmol) of europium acetate hydrate ([Eu(OOCCH3) 3H2O]) in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), uniformly stir at room temperature, and prepare a europium (III) acetate solution;

[0054] (2) Then dissolve (61.6 mg, 0.34 mmol) of 2-amino terephthalic acid in a mixture of N,N-dimethylformamide (15 mL), ethanol (1 mL) and water (1 mL), uniformly stir at room temperature, and prepare a 2-amino terephthalic acid solution;

[0055] (3) Add 1 mL of deionized water to the 3 mL of 2-aminoterephthalic acid solution in step (2), transfer it to a glass culture dish, and then slowly add 3 mL of 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 while adding and shaking. After standing at room temperature for 24 h, wash it 3 times with DMF and then 3 times with ethanol. After filtration, air dry to obtain the Eu-MOF ratio fluorescent probe.

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

[0057] Experimental Example 1

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

[0059] Depend on Figure 2 The powder diffraction (PXRD) results show that the powder diffraction results obtained in Example 1 are in good agreement with the single-crystal structure simulation results, indicating that the product obtained in this invention has high purity. The chemical formula of the probe prepared in this invention is {[Eu(C8H5NO4)}. 1.5 [(DMF)2]·2H2O·DMF}n, where n is an integer greater than 1, abbreviated as Eu-MOF; where C8H5NO4 2- The DMF was obtained by deprotonating the ligand 2-aminoterephthalic acid, and the DMF was N,N-dimethylformamide. The resulting Eu-MOF ratiometric fluorescent probe crystal belongs to the triclinic crystal system, space group P-1, and its unit cell parameters are as follows: α = 104.553(5), b = 109.857(4), γ = 95.438(5). The asymmetric unit cell of this Eu-MOF material contains one crystallographically independent Eu... 3+ 1.5 independent C8H5NO4 2- It contains ions and 2 DMF molecules, including 2 free water molecules and 1 free DMF molecule.

[0060] Experimental Example 2

[0061] Figure 3 The image shows a microscope photograph of the Eu-MOF material of this invention. It can be seen that Eu-MOF is a bulk crystal with a size of approximately 0.18 μm and uniform size.

[0062] Experimental Example 3

[0063] Figure 4 The thermogravimetric curve of the Eu-MOF material of this invention shows that Eu-MOF begins to lose weight at around 160℃. In the first stage (160-230℃), approximately 18.1% weight is lost (theoretical value is 16.1%), mainly due to free water molecules and DMF molecules in Eu-MOF. In the second stage (230-580℃), approximately 22.2% weight is lost (theoretical value is 21.6%), mainly due to DMF molecules coordinated in Eu-MOF. After that, the remaining structure begins to decompose, indicating that the main framework structure of the Eu-MOF ratiometric fluorescent probe has good thermal stability.

[0064] Test Example 4

[0065] The application of the above-mentioned Eu-MOF ratiometric fluorescent probe in the detection of formaldehyde includes the following steps: The obtained Eu-MOF ratiometric fluorescent probe is ground for 40 min; 10 mg of the ground Eu-MOF is dispersed in 100 mL of DMF; and the mixture is sonicated (ultrasonic power 60-70 Hz) for 40 min to prepare a well-dispersed and stable Eu-MOF suspension. Then, 3 mL of the Eu-MOF suspension is added to a cuvette, and its fluorescence spectrum is measured using a fluorescence spectrometer. The results are as follows: Figure 5 As shown. By Figure 5 The excitation and emission spectra show that Eu-MOF has dual emission peaks at λ=430nm (blue light) and λ=617nm (red light), providing a good platform for ratiometric fluorescence detection of formaldehyde.

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

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

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

[0069] Figure 8 The filter paper is used as a self-supporting film, the filter paper is immersed in the Eu-MOF suspension, ultrasonic dispersion, and air natural drying. The Eu-MOF probe loading film is obtained. The probe loaded film is exposed to formaldehyde solutions with different concentrations (10μM, 20μM, 30μM, 40μM, 50μM, 60μM, 70μM, 80μM, 90μM, 100μM, 200μM, 400μM, 1000μM), and under ultraviolet irradiation, the color change from red to blue can be directly observed, indicating that the probe can detect formaldehyde with high sensitivity and high selectivity, and realize visual detection.

[0070] Figure 9 The relative intensity change of the fluorescence spectrum of the Eu-MOF material of the application as a ratio fluorescence probe for detecting formaldehyde within 1 week of storage time is Figure 9 It can be known that the Eu-MOF fluorescence ratio probe of the application shows good stability when detecting the formaldehyde concentration.

[0071] The above is only the preferred embodiment of the application, which is not limited to the above examples, and for those skilled in the art, various modifications and changes can be made under the principle of the application. Any modification, improvement, etc. shall be considered within the protection scope of the application.

Claims

1. A method for preparing a Eu-MOF ratiometric fluorescent probe, characterized in that, The method comprises the following steps: The Eu-acetate solution is added to the 2-amino terephthalic acid solution, and after standing, washing and drying, the Eu-MOF ratio fluorescent probe is obtained; the concentration of the Eu-acetate solution is 10-20 mmol / L, the concentration of the 2-amino terephthalic acid solution is 20 mmol / L, the volume ratio of the Eu-acetate solution to the 2-amino terephthalic acid solution is 1:(1-3), and the solvent of the Eu-acetate solution and the 2-amino terephthalic acid solution is N,N-dimethylformamide, ethanol and water mixed in a volume ratio of 15:1:1; The Eu-acetate solution is added to the 2-amino terephthalic acid solution in a dropwise manner, and the dropwise adding speed is 0.2-0.6 μL / s; the standing is carried out at room temperature for 24 h. The Eu-MOF ratio fluorescent probe has a chemical formula of {[Eu(C8H5NO4) 1.5 (DMF)2]•2H2O•DMF}n, wherein n is an integer greater than 1; wherein C8H5NO4 2- is a ligand obtained by deprotonating 2-amino terephthalic acid; and the Eu-MOF ratio fluorescent probe crystal belongs to a triclinic system, a space group is P-1, and cell parameters are: a = 10.3844(17) Å, b = 11.1765(18) Å, c = 12.693(2) Å, α = 104.553(5), b = 109.857(4), and γ = 95.438(5).

2. A Eu-MOF ratiometric fluorescent probe, characterized in that, The Eu-MOF ratio fluorescent probe is prepared by the preparation method according to claim 1.

3. The application of the Eu-MOF ratio fluorescent probe according to claim 2 in detecting formaldehyde. 4.The Eu-MOF ratiometric fluorescent probe for detecting formaldehyde according to claim 3, characterized in that, The Eu-MOF ratio fluorescent probe is ground and then ultrasonically dispersed in DMF to prepare an Eu-MOF suspension, and then the to-be-detected substance is added to obtain a to-be-detected sample solution, and the fluorescence spectrum is tested. 5.The Eu-MOF ratiometric fluorescent probe for detecting formaldehyde according to claim 4, characterized in that, The detection specifically comprises the following steps: grinding the Eu-MOF ratio fluorescent probe, ultrasonic dispersion in DMF to prepare an Eu-MOF suspension, adding formaldehyde to the suspension to prepare formaldehyde sample solutions with different concentrations; testing the fluorescence spectrum, calculating the ratio I 430 / I 617 of the fluorescence intensity at wavelengths of 430 nm and 617 nm, and obtaining a standard curve of the fluorescence intensity ratio and the formaldehyde concentration. The substance to be tested is added to the Eu-MOF suspension to obtain a sample solution to be tested, the fluorescence spectrum is tested, and I is recorded 430 / I 617 The formaldehyde content in the substance to be tested is calculated according to the standard curve.

6. The use of the Eu-MOF ratiometric fluorescent probe according to claim 4 or 5 in detecting formaldehyde, characterized in that, The Eu-MOF ratio fluorescent probe is ground to 60-80 mesh, and the concentration of the Eu-MOF suspension is 0.1 mg / mL.

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