Nd (III) metal organic framework crystalline material and preparation method and fluorescence sensing application thereof

Abstract

The invention relates to the technical field of fluorescence sensing, in particular to an Nd (III) metal organic framework crystalline material as well as a preparation method and fluorescence sensing application thereof. According to the Nd (III) metal organic framework crystalline state material, Nd (III) serves as a central metal ion and is coordinated with eight oxygen atoms to form a dodecahedron structure, adjacent Nd (III) form a one-dimensional chain structure through [H (4-CPCA) 2] 3-bridging coordination, and one-dimensional chains are further stacked through intermolecular acting force to form a three-dimensional framework structure. The Nd (III) metal organic framework crystalline material has good fluorescent property and stability and can be applied to the field of fluorescence sensing.

Description

Technical Field

[0001] The present invention relates to the field of fluorescence sensing technology, and in particular, to a Nd(III) metal-organic framework crystalline material, a preparation method thereof, and a fluorescence sensing application. Background Art

[0002] With the development of human production and technological progress, this has also brought harm to the natural environment, especially the increasing pollutants discharged into the natural world. Pollutants refer to substances that can directly or indirectly harm humans after entering the environment. Harmful substances such as heavy metal ions and pharmaceutical antibiotics have seriously affected the healthy life of humans. Therefore, under the current situation, the detection of pollutants has become an important issue for providing people with a good living environment. Currently, the commonly used methods for detecting substances mainly include mass spectrometry (MS), atomic fluorescence spectrometry (AFS), inductively coupled plasma spectrometry (ICP-MS), gas chromatography (GC), electrochemical analysis (EA), electron paramagnetic resonance (EPR), etc. However, these methods still have certain limitations.

[0003] Therefore, it is necessary and urgent to develop a method with high sensitivity, rapidity, convenience and low cost. Rare earth elements can combine with organic ligands to form rare earth complexes. Whether it is a variety of coordination numbers or the frequent occurrence of rare coordination geometries, it reflects the richness and uniqueness of the coordination modes of rare earth elements. Due to the special electronic layer structure of rare earth elements and the "antenna effect" of ligands, rare earth complexes have spectral properties that are incomparable to those of general substances, such as high color purity, stable luminescence performance, strong specificity, wide emission wavelength and long fluorescence lifetime. In recent years, many rare earth complexes with good luminescence properties have been applied to the preparation of fluorescence sensors, such as detecting drugs, cations, anions, antibiotics and temperature sensing. Therefore, fluorescence sensing based on rare earth complexes has gradually become an important research tool in the fields of chemistry, life science, basic medicine and environmental detection. Summary of the Invention

[0004] The present invention provides a Nd(III) metal-organic framework crystalline material, a preparation method thereof, and a fluorescence sensing application. The pyridazine carboxylic acid derivative H2(4-CPCA) is selected as the organic ligand, and coordinated with the rare earth metal neodymium to obtain the Nd(III) metal-organic framework crystalline material. The chemical formula of its single molecule is {Nd[H(4-CPCA)2]} n , with Nd(III) as the central metal ion, coordinating with 8 oxygen atoms respectively to form a dodecahedron structure. Adjacent Nd(III) are connected by [H(4-CPCA)2] 3-Bridging coordination forms a one-dimensional chain structure, and the one-dimensional chains are further stacked through intermolecular forces to form a three-dimensional framework structure. It has good fluorescence properties and stability and can be applied in the field of fluorescence sensing.

[0005] To solve the above technical problems, the present invention provides a crystalline Nd(III) metal-organic framework material, and the single-molecule chemical formula of the crystalline Nd(III) metal-organic framework material is {Nd[H(4-CPCA)2]}. n .

[0006] The present invention also provides a preparation method of the above-mentioned crystalline Nd(III) metal-organic framework material, which includes the following steps: S1. Add neodymium salt and H2(4-CPCA) to H2O, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.1 - 6.3, and carry out a constant-temperature reaction to obtain a reaction product; S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product, and wash, filter, and dry the crystallization product in sequence to obtain the crystalline Nd(III) metal-organic framework material.

[0007] According to the preparation method of the crystalline Nd(III) metal-organic framework material provided by the present invention, the neodymium salt in S1 is any one of NdCl3·6H2O or Nd(NO3)3·6H2O, the temperature condition of the constant-temperature reaction is 110 °C, and the time condition of the constant-temperature reaction is 48 h.

[0008] According to the preparation method of the crystalline Nd(III) metal-organic framework material provided by the present invention, H2(4-CPCA) in S1 is 1-(4-carboxyphenyl-4-oxo-pyridazine)-3-carboxylic acid, and the structural formula of H2(4-CPCA) is: .

[0009] According to the preparation method of the crystalline Nd(III) metal-organic framework material provided by the present invention, the molar ratio of the neodymium salt and H2(4-CPCA) in S1 is 0.05 - 0.10 mmol: 0.05 - 0.10 mmol, and the volume of H2O is 2 mL.

[0010] According to the preparation method of the crystalline Nd(III) metal-organic framework material provided by the present invention, the solution used to adjust the pH value of the mixed solution in S1 is sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.3 mol / L.

[0011] According to the preparation method of the Nd(III) metal-organic framework crystalline material provided by the present invention, the filtration in S2 is vacuum filtration, the drying temperature is 30 °C, and the drying time is 3 h.

[0012] The present invention also provides an application of the above Nd(III) metal-organic framework crystalline material, and the Nd(III) metal-organic framework crystalline material is applied to fluorescence sensing.

[0013] The present invention has the following advantages compared with the prior art: In the present invention, the Nd(III) metal-organic framework crystalline material {Nd[H(4-CPCA)2]} is prepared by a one-pot thermal method. n , with Nd(III) as the central metal ion, coordinated with 8 oxygen atoms respectively to form a dodecahedron structure. Adjacent Nd(III) are bridged and coordinated by [H(4-CPCA)2] 3- to form a one-dimensional chain structure, and the one-dimensional chains are further stacked through intermolecular forces to form a three-dimensional framework structure. Because {Nd[H(4-CPCA)2]} n has good fluorescence properties and stability, it can be applied to the field of fluorescence sensing. Description of the Drawings

[0014] Figure 1 is the single molecule diagram of the Nd(III) metal-organic framework crystalline material; Figure 2 is the three-dimensional supramolecular stacking diagram of the Nd(III) metal-organic framework crystalline material; Figure 3 is the IR diagram of the Nd(III) metal-organic framework crystalline material; Figure 4 is the XRD diagram of the Nd(III) metal-organic framework crystalline material; Figure 5 is the solid-state fluorescence spectrum diagram of the Nd(III) metal-organic framework crystalline material; Figure 6 is the fluorescence spectrum after adding different volumes of Pb 2+ solution (0.1 mmol / L) to the Nd(III) metal-organic framework crystalline material; Figure 7 is the linear fitting diagram of the fluorescence change value of the Nd(III) metal-organic framework crystalline material in Pb 2+ solution; Figure 8 is the fluorescence spectrum after adding different volumes of tetracycline solution (0.01 mmol / L) to the Nd(III) metal-organic framework crystalline material; Figure 9It is a linear fitting diagram of the fluorescence change value of Nd(III) metal-organic framework crystalline material in Tetracycline solution; Figure 10 It is the anti-interference effect of Nd(III) metal-organic framework crystalline material on the specific fluorescence changes of Pb 2+ and Tetracycline. Specific implementation manners

[0015] Example 1

[0016] This example provides a preparation method of Nd(III) metal-organic framework crystalline material.

[0017] S1. Add 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) into a glass scintillation vial containing 2 mL of H2O, mix them evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.3 with a 0.3 mol / L sodium hydroxide solution, and carry out a solvothermal constant-temperature reaction on the mixed solution at 110 °C for 48 h to obtain a reaction product; Among them, H2(4-CPCA) is 1-(4-carboxyphenyl-4-oxopyridazine)-3-carboxylic acid, and the structural formula of the H2(4-CPCA) is: ; S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product, rinse the crystallization product with deionized water, then carry out vacuum filtration to obtain a transparent block crystal, and place the transparent block crystal in an oven at 30 °C for constant-temperature drying for 3 h to obtain Product 1, that is, Nd(III) metal-organic framework crystalline material, and the yield is about 82.7%.

[0018] Example 2 This example provides a preparation method of Nd(III) metal-organic framework crystalline material.

[0019] S1. Add 0.1 mmol of Nd(NO3)3·6H2O and 0.1 mmol of H2(4-CPCA) into a glass scintillation vial containing 2 mL of H2O, mix them evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.7 with a 0.3 mol / L sodium hydroxide solution, and carry out a solvothermal constant-temperature reaction on the mixed solution at 110 °C for 48 h to obtain a reaction product; S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product. Rinse the crystallization product with deionized water, then perform vacuum filtration to obtain transparent blocky crystals. Place the transparent blocky crystals in an oven at 30 °C for constant-temperature drying for 3 h to obtain the product Nd(III) metal-organic framework crystalline material, with a yield of approximately 83.6%.

[0020] Example 3 This example provides a preparation method for Nd(III) metal-organic framework crystalline material.

[0021] S1. Add 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) to a glass scintillation vial containing 2 mL of H2O, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.9 with a 0.3 mol / L sodium hydroxide solution, and carry out a solvothermal constant-temperature reaction on the mixed solution at 110 °C for 48 h to obtain a reaction product. S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product. Rinse the crystallization product with deionized water, then perform vacuum filtration to obtain transparent blocky crystals. Place the transparent blocky crystals in an oven at 30 °C for constant-temperature drying for 3 h to obtain the product Nd(III) metal-organic framework crystalline material, with a yield of approximately 83.1%.

[0022] Example 4 This example provides a preparation method for Nd(III) metal-organic framework crystalline material.

[0023] S1. Add 0.1 mmol of Nd(NO3)3·6H2O and 0.1 mmol of H2(4-CPCA) to a glass scintillation vial containing 2 mL of H2O, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 6.2 with a 0.3 mol / L sodium hydroxide solution, and carry out a solvothermal constant-temperature reaction on the mixed solution at 110 °C for 48 h to obtain a reaction product. S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product. Rinse the crystallization product with deionized water, then perform vacuum filtration to obtain transparent blocky crystals. Place the transparent blocky crystals in an oven at 30 °C for constant-temperature drying for 3 h to obtain the product Nd(III) metal-organic framework crystalline material, with a yield of approximately 83.5%.

[0024] Example 5 This example provides a preparation method for Nd(III) metal-organic framework crystalline material.

[0025] S1. Add 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) into a glass scintillation vial containing 2 mL of H2O, mix them evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 6.3 with 0.3 mol / L sodium hydroxide solution, and carry out a solvothermal constant-temperature reaction on the mixed solution at 110 °C for 48 h to obtain a reaction product; S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product, rinse the crystallization product with deionized water, then carry out vacuum filtration to obtain a transparent block crystal, place the transparent block crystal in an oven at 30 °C for constant-temperature drying for 3 h to obtain the product Nd(III) metal-organic framework crystalline material, and the yield is about 82.4%.

[0026] Example 6 Take the final product 1 prepared in Example 1, that is, the Nd(III) metal-organic framework crystalline material, for characterization.

[0027] (1)Crystal structure determination of Nd(III) metal-organic framework crystalline material Select a single crystal with a size of 0.12×0.11×0.11 under a microscope and carry out X-ray diffraction experiments at room temperature.

[0028] Collect diffraction data on a Bruker-ApexП X-ray single crystal diffractometer, use Mo-Kα radiation (λ = 0.71073 Å) monochromatized by a graphite monochromator, collect diffraction points in the ω-2θ scanning mode, all data are corrected by factors and empirical absorption, the crystal structure is solved by a direct method using a program, hydrogen atoms are determined by difference Fourier synthesis and fixed at the calculated optimal positions, and the SHELX-97 program is used to perform full-matrix least-squares refinement on all non-hydrogen atoms and their anisotropic thermal parameters. The main crystallographic determination data of the Nd(III) metal-organic framework crystalline material are shown in Tables 1 and 2, and the important bond lengths and bond angles data of the Nd(III) metal-organic framework crystalline material are shown in Table 2. The crystal structure is as Figure 1 shown, and the three-dimensional supramolecular structure of the metal-organic framework crystalline material is as Figure 2 shown.

[0029] Table 1

[0030] Table 2

[0031] Symmetry codes: #1 x, y, z; #2 -x, y, -z + 1 / 2; #3 x + 1 / 2, y + 1 / 2, z; In Table 1, a, b, and c represent the edge lengths of the crystal in the three crystallographic axis directions, and α, β, and γ represent the angles between the three axes of a and b, a and c, and b and c, respectively; Z Z is the number of molecules contained in the unit cell; the diffraction index range of the restraint factor is (h, k, l); F(000) is the number of electrons in the unit cell; Final 1 R indices [I>2σ(I)] are the residual factor R values for observable diffraction points; R is the non-weighted goodness-of-fit factor; both R1 and wR2 are weighted goodness-of-fit factors; In Table 2, Nd(1) in the first row refers to Nd atom 1 in the single crystal of the Nd(III) metal-organic framework crystalline material, O(5) refers to O atom 5 in the single crystal of the Nd(III) metal-organic framework crystalline material, and Nd(1)-O(5) represents the bond length between Nd atom 1 and O atom 5, and its bond length is 2.422±2, where 2 is the standard deviation; O(5)-Nd(1)-O(2)#2 represents the bond angle between O atom 5, Nd atom 1, and the symmetry atom 2 of O atom 2, and its bond angle is 146.11±8; Figure 1 is the single-molecule diagram of Product 1, Figure 2 is the three-dimensional supramolecular diagram of Product 1. According to Figure 1 and Figure 2 it can be seen that the molecular formula of the product is {Nd[H(4-CPCA)2]} n , that is, the Nd(III) metal-organic framework crystalline material.

[0032] From Figure 1 and Figure 2 it can be seen that the Nd(III) metal-organic framework crystalline material prepared in this example uses Nd 3+ as the central metal ion, which coordinates with 8 oxygen atoms respectively to form a dodecahedron structure. Adjacent Nd(III) are bridged and coordinated through [H(4-CPCA)2] 3- to form a one-dimensional chain structure, and the one-dimensional chains are further stacked through intermolecular forces to form a three-dimensional framework structure.

[0033] The metal-organic framework crystalline material {Nd[H(4-CPCA)2]} n crystallizes in the space group C2 / c and belongs to the monoclinic system. Its asymmetric structural unit includes 1 Nd 3+ , 2 H(4-CPCA) - that have lost one hydrogen. The central metal ion Nd 3+It coordinates with 8 oxygen atoms to form a dodecahedral structure. Among them, 4 oxygen atoms (O1, O2, O1, O2) come from the carboxyl and carbonyl groups on the chelating ligand H2(4-CPCA), and the other 4 oxygen atoms (O3, O5, O3, O5) come from the carboxyl groups on the chelating ligand H2(4-CPCA). Along the b-axis direction, it coordinates with 8 oxygen atoms respectively to form a dodecahedral structure. The adjacent Nd(III) are bridged and coordinated to form a one-dimensional chain structure, and the one-dimensional chains are further stacked through intermolecular forces to form a three-dimensional framework structure. Due to its good fluorescence properties and good stability, it can be applied in the field of fluorescence sensing. 3- The bridging coordination forms a one-dimensional chain structure, and the one-dimensional chains are further stacked through intermolecular forces to form a three-dimensional framework structure. Due to its good fluorescence properties and good stability, it can be applied in the field of fluorescence sensing.

[0034] (2)Characterization by infrared (IR) spectrum Figure 3 The IR spectra of the Nd(III) metal-organic framework crystalline material and H2(4-CPCA) are shown. The infrared spectral data of the sample were collected in the range of 500 - 4000 cm -1 , using KBr pellet pressing. It can be seen from Figure 3 that the three peaks between 1510 - 1596 cm -1 are the stretching vibration peaks of the benzene ring, and the stretching vibration peak of the carbonyl group is at 1652 cm -1 . In addition, the strong peak at 1600 cm -1 in H2(4-CPCA) accurately indicates the presence of C-N.

[0035] (3)Characterization of the phase purity of the Nd(III) metal-organic framework crystalline material The powder XRD characterization results of the Nd(III) metal-organic framework crystalline material using a Bruker / D8 Advance X-ray diffractometer show its reliable phase purity, as Figure 4 shown.

[0036] (4)Fluorescence sensing performance of the Nd(III) metal-organic framework crystalline material Since heavy metal ions are often distributed in water, it is more convenient to study the fluorescence sensing performance of the Nd(III) metal-organic framework crystalline material towards Pb 2+ and Tetracycline ions in aqueous solution.

[0037] The photoluminescence (PL) properties of the Nd(III) metal-organic framework crystalline material were studied at room temperature, and fluorescence sensing experiments were carried out in an aqueous suspension. Figure 5 is the solid-state fluorescence spectrum of the Nd(III) metal-organic framework crystalline material. It can be seen from Figure 5 that the maximum emission peak of the Nd(III) metal-organic framework crystalline material is 423 nm.

[0038] A 2 mg powder sample of the Nd(III) metal-organic framework crystalline material was immersed in 4 mL of water for dissolution, and then ultrasonically treated for 20 min to obtain a stable suspension. Sodium + , potassium + , lead 2+ , cadmium 2 + , zinc 2+ , manganese 2+ , barium 2+ , mercury 2+ , calcium 2+ , cobalt 2+ , silver + , nickel 2+ , copper 2+ , europium 3+ , samarium 3+ , gadolinium 3+ , praseodymium 3+ , dysprosium 3+ , lanthanum 3+ , holmium 3+ , lutetium 3+ and other metal cations and suspension solutions of tetracycline, ascorbic acid, and dopamine were prepared for qualitative and anti-interference studies. Each time, 3 μL of the above-prepared suspension solution was used for quantitative titration studies, and the fluorescence spectra were recorded and collected under excitation at a wavelength of 378 nm.

[0039] At an excitation wavelength of 378 nm, the corresponding fluorescence emission intensity of the Nd(III) metal-organic framework crystalline material was as Figure 6 shown. By comparing the changes in luminescence intensity caused by each metal ion, fluorescence quenching effects occurred with the addition of Pb 2+ and tetracycline.

[0040] To study the ability of the Nd(III) metal-organic framework crystalline material to act as a fluorescence probe for detecting Pb 2+ and tetracycline, further analysis was carried out based on the obtained experimental data. Figure 6 shows the fluorescence spectra of the Nd(III) metal-organic framework crystalline material after adding different volumes of Pb 2+ solution (0.1 mmol / L). As the concentration of Pb 2+ increased, the fluorescence intensity of the metal-organic framework crystalline material gradually decreased. Figure 7 is the linear fitting graph of the fluorescence change value of the Nd(III) metal-organic framework crystalline material in the Pb 2+ solution; according to the Stern-Volmer equation (I0 - I) / I = K svφ (I0 and I are the fluorescence intensities before and after adding Pb 2+ respectively, and φ is the volume fraction of Pb 2+ , and K sv is the quenching constant), and the linear correlation coefficient R 2 = 0.9995 is obtained by fitting.

[0041] Figure 8 are the fluorescence spectra of the crystalline Nd(III) metal-organic framework material after adding different volumes of Tetracycline solution (0.01 mmol / L), Figure 9 is the linear fitting graph of the fluorescence change value of the crystalline Nd(III) metal-organic framework material in the Tetracycline solution. It can be seen from Figure 8 and Figure 9 that the fluorescence intensity of the crystalline Nd(III) metal-organic framework material at 423 nm wavelength gradually weakens with the increase of the Tetracycline concentration. And there is a good linear relationship in a certain concentration range (R 2 = 0.9958).

[0042] The limit of detection (LOD) is also an important indicator to measure the fluorescence detection ability. The limit of detection (LOD) can be calculated by the formula 3σ / K sv . (where σ is the standard deviation value of the fluorescence intensity of 11 blank experiments of the test complex without adding any ions). It is calculated from the limit of detection formula that the limit of detection of the crystalline Nd(III) metal-organic framework material for Pb 2+ is: 4.86×10 -4 mol·L -1 , and the limit of detection for Tetracycline is: 1.95×10 -5 mol·L -1 . Compared with the fluorescence sensors of other crystalline metal-organic framework materials, the crystalline Nd(III) metal-organic framework material has a lower limit of detection and a wider linear detection range.

[0043] To further explore whether the crystalline Nd(III) metal-organic framework material can selectively detect Pb 2+ and Tetracycline, Na + with a concentration of 0.1 mmol / L, K + , Cd 2+ , Zn 2+ , Mn 2+ , Hg 2+ , Ca 2+ , Co 2+, Ag + , Ni 2+ , Cu 2+ , Eu 3+ , Sm 3+ , Gd 3+ , Pr 3+ , Dy 3+ , La 3+ , Ho 3+ , Lu 3+ and other metal ions. After ultrasonic treatment to form a stable suspension, Nd(III) metal-organic framework crystalline material ions are added. At room temperature, when the excitation wavelengths are 378 nm respectively, their fluorescence emission spectra are detected. The results are as Figure 10 shown. It can be seen that even in the presence of other interfering metal ions, the Nd(III) metal-organic framework crystalline material can still selectively detect Pb 2+ and Tetracycline.

[0044] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes and equivalent variations made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A crystalline Nd(III) metal-organic framework material, characterized in that, The single-molecule chemical formula of the Nd(III) metal-organic framework crystalline material is {Nd[H(4-CPCA)2]} n .

2. A preparation method of the Nd(III) metal-organic framework crystalline material as described in claim 1, characterized in that, It includes the following steps: S1. Add neodymium salt and H2(4-CPCA) into H2O, mix them evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.1 - 6.3, and carry out a constant-temperature reaction to obtain a reaction product; S2. Cool the reaction product obtained in S1 for crystallization to obtain a crystallization product, and successively wash, filter and dry the crystallization product to obtain a crystalline Nd(III) metal-organic framework material.

3. The preparation method of the Nd(III) metal-organic framework crystalline material according to claim 2, characterized in that, The neodymium salt described in S1 is any one of NdCl3·6H2O or Nd(NO3)3·6H2O, the temperature condition of the constant-temperature reaction is 110 °C, and the time condition of the constant-temperature reaction is 48 h.

4. The preparation method of the Nd(III) metal-organic framework crystalline material according to claim 2, wherein, The H2(4-CPCA) described in S1 is 1-(4-carboxyphenyl-4-oxo-pyridazine)-3-carboxylic acid, and the structural formula of the H2(4-CPCA) is: 。 5. The preparation method of the Nd(III) metal-organic framework crystalline material according to claim 2, wherein The molar ratio of the neodymium salt and H2(4-CPCA) described in S1 is 0.05 - 0.10 mmol:0.05 - 0.10 mmol, and the volume of the H2O is 2 mL.

6. The preparation method of the Nd(III) metal-organic framework crystalline material according to claim 2, characterized in that, The solution used to adjust the pH value of the mixed solution in S1 is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.3 mol / L.

7. The preparation method of the Nd(III) metal-organic framework crystalline material according to claim 2, wherein The filtration in S2 is vacuum filtration, the drying temperature is 30 °C, and the drying time is 3 h.

8. Use of the Nd(III) metal-organic framework crystalline material as described in claim 1, characterized in that, The crystalline Nd(III) metal-organic framework material is applied to fluorescence sensing.

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