Nd (III)-based hydrogen bond 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 a preparation method and application of an Nd (III)-based hydrogen bond organic framework crystalline material. According to the Nd (III)-based hydrogen bond organic framework crystalline state material, Nd (III) serves as a central metal ion and is coordinated with 9 oxygen atoms, and adjacent Nd (III) are connected through H2 (4-CPCA) ligands to form a one-dimensional chain structure. One-dimensional chains are bridged through H2 (4-CPCA) ligands to form a two-dimensional double-layer planar structure, and two-dimensional surfaces are further stacked through the interaction of a large number of intermolecular hydrogen bonds to form a three-dimensional supramolecular structure. The Nd (III)-based hydrogen bond 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 technical field of fluorescence sensing, and in particular to an Nd(III)-based hydrogen-bonded organic framework crystalline material, a preparation method thereof, and a fluorescence sensing application. Background Art

[0002] Rare earth ions have special 4f electron orbits, with 1639 electron energy levels, and nearly 200,000 possible transition channels between energy levels, which is 1 - 3 orders of magnitude more than other elements. There are approximately 30,000 observable spectral lines in its spectrum, covering electromagnetic radiation of various wavelengths from ultraviolet light, visible light to infrared light region. Therefore, it is also called a treasure trove of luminescent materials. However, single rare earth ions usually hardly emit strong light. A common method is to form rare earth complexes by coordinating rare earth ions with suitable ligands. When excited by other energy, the energy is absorbed by the ligand and transferred to the rare earth ion. Subsequently, when the rare earth ion transitions back to the ground state, it releases energy in the form of luminescence.

[0003] The luminescence of LMOFs can be divided into two cases: one is the luminescence based on the material skeleton itself: with the metal center as the luminescence source, among which lanthanide metal-organic frameworks (Ln-MOFs) have attracted much attention due to their characteristic emission spectra and high luminescence efficiency. The luminescence of lanthanide ions mainly depends on the sensitization of organic ligands. Therefore, when designing the organic ligands of Ln-MOFs materials, in addition to having strong light absorption ability, it is also necessary to consider the matching degree between the triplet excited state of the selected organic ligand and the emission energy level of a specific lanthanide metal. With organic ligands containing p-conjugated systems as the luminescence source, among which LMOFs with porous structures can be constructed with strong fluorescent organic groups (such as biphenyl, porphyrin, pyrene, etc.) as the center. The luminescence properties of LMOFs are the same as those of the original ligands, unless metal-ligand charge transfer (MLCT) or ligand-metal charge transfer (LMCT) occurs, resulting in a slight shift in the emission wavelength. The other is the luminescence generated by host-guest interaction: LMOFs can combine with a variety of guest molecules to form a variety of composite materials. For example, dyes, quantum dots or luminescent nanomaterials are embedded or adsorbed inside or on the surface of LMOFs. The luminescence properties of these composite materials can exist independently or interact with each other. If the emission spectrum of the energy donor overlaps with the absorption spectrum of the energy acceptor and the distance is less than 10 nm, it can trigger Förster resonance energy transfer (FRET), resulting in the weakening of the donor fluorescence and simultaneously exciting the acceptor to luminesce. Summary of the Invention

[0004] The present invention provides a Nd(III)-based hydrogen-bonded organic framework crystalline material, its preparation method and fluorescence sensing application. A Nd(III)-based hydrogen-bonded organic framework crystalline material is prepared by using a pyridazine carboxylic acid derivative H2(4-CPCA) and 1,10-phenanthroline as organic ligands to coordinate with rare earth metal neodymium (Nd) to obtain a Nd(III)-based hydrogen-bonded organic framework crystalline material, and the chemical expression of its single molecule is {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} n , with Nd(III) as the central metal ion, coordinating with 9 oxygen atoms respectively. Adjacent Nd(III) are connected by the H2(4-CPCA) ligand to form a one-dimensional chain structure. The one-dimensional chains are bridged by the H2(4-CPCA) ligand to form a two-dimensional double-layer planar structure, and the two-dimensional planes are further stacked through a large number of intermolecular hydrogen bond interactions to form a three-dimensional supramolecular structure, which has good fluorescence properties and stability and can be applied to the field of fluorescence sensing.

[0005] To solve the above technical problems, the present invention provides a Nd(III)-based hydrogen-bonded organic framework crystalline material, and the chemical expression of the Nd(III)-based hydrogen-bonded organic framework crystalline material is {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} n .

[0006] The present invention also provides a preparation method of the above Nd(III)-based hydrogen-bonded organic framework crystalline material, including the following steps: S1. Add neodymium salt, H2(4-CPCA) and 1,10-phenanthroline into H2O, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.2 - 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 a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0007] According to the preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material provided by the present invention, it is characterized in that 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 Nd(III)-based hydrogen-bonded organic framework crystalline material provided by the present invention, H2(4-CPCA) in S1 is 1-(4-carboxyphenyl-4-oxopyridazine)-3-carboxylic acid, and the structural formula of H2(4-CPCA) is:

[0009] According to the preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material provided by the present invention, the molar ratio of the neodymium salt, H2(4-CPCA), and 1,10-phenanthroline in S1 is 0.10 mmol to 0.15 mmol: 0.05 mmol to 0.10 mmol: 0.05 mmol to 0.10 mmol, and the volume of the H2O solvent is 2 mL.

[0010] According to the preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material provided by the present invention, the solution for adjusting the pH in S1 is a 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)-based hydrogen-bonded 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)-based hydrogen-bonded organic framework crystalline material, and the Nd(III)-based hydrogen-bonded 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)-based hydrogen-bonded organic framework crystalline material {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} is prepared by a one-pot hydrothermal method n , and in this Nd(III)-based hydrogen-bonded organic framework crystalline material, Nd(III) is used as the central metal ion, which coordinates with 9 oxygen atoms respectively. Adjacent Nd(III) are connected by the H2(4-CPCA) ligand to form a one-dimensional chain structure. The one-dimensional chains are bridged by the H2(4-CPCA) ligand to form a two-dimensional bilayer planar structure, and the two-dimensional planes are further stacked through a large number of intermolecular hydrogen bond interactions to form a three-dimensional supramolecular structure. Due to its good fluorescence properties and stability, it can be applied to the field of fluorescence sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the single molecule diagram of the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 2 is the three-dimensional supramolecular stacking diagram of the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 3 is the IR diagram of the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 4 is the XRD diagram of the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 5 It is the solid-state fluorescence spectrum of the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 6 It is the fluorescence spectrum after adding different volumes of Fe 3+ solution (0.1 mmol / L) to the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 7 It is the linear fitting graph of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in Fe 3+ solution; Figure 8 It is the fluorescence spectrum after adding different volumes of La 3+ solution (0.1 mmol / L) to the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 9 It is the linear fitting graph of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in La 3+ solution; Figure 10 It is the fluorescence spectrum after adding different volumes of Mn 2+ solution (0.1 mmol / L) to the Nd(III)-based hydrogen-bonded organic framework crystalline material; Figure 11 It is the linear fitting graph of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in Mn 2+ solution; Figure 12 It is the anti-interference effect of the Nd(III)-based hydrogen-bonded organic framework crystalline material on the specific fluorescence changes of Fe 3+ , La 3+ and Mn 2+ ; Specific implementation mode

[0015] Example 1 This example provides a preparation method of a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0016] S1. Add 0.10 mmol of NdCl3·6H2O, 0.05 mmol of H2(4-CPCA) and 0.05 mmol of 1,10-phenanthroline 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 5.2 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; Among them, H2(4-CPCA) is 1-(4-carboxyphenyl-4-oxo-pyridazine)-3-carboxylic acid, and the structural formula of the H2(4-CPCA) is:

[0017] 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 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, namely the Nd(III)-based hydrogen-bonded organic framework crystalline material, with a yield of approximately 84.2%.

[0018] Example 2 This example provides a method for preparing a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0019] S1. Add 0.10 mmol of Nd(NO3)3·6H2O, 0.05 mmol of H2(4-CPCA), and 0.05 mmol of 1,10-phenanthroline to a glass scintillation vial containing 2 mL of H2O, mix well to obtain a mixed solution, adjust the pH value of the mixed solution to 5.5 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 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 the Nd(III)-based hydrogen-bonded organic framework crystalline material, with a yield of approximately 83.5%.

[0020] Example 3 This example provides a method for preparing a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0021] S1. Add 0.10 mmol of NdCl3·6H2O, 0.05 mmol of H2(4-CPCA), and 0.05 mmol of 1,10-phenanthroline to a glass scintillation vial containing 2 mL of H2O, mix well to obtain a mixed solution, adjust the pH value of the mixed solution to 5.8 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 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 the Nd(III)-based hydrogen-bonded organic framework crystalline material, with a yield of approximately 82.6%.

[0022] Example 4 This example provides a method for preparing a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0023] S1. Add 0.10 mmol of Nd(NO3)3·6H2O, 0.05 mmol of H2(4-CPCA), and 0.05 mmol of 1,10-phenanthroline to a glass scintillation vial containing 2 mL of H2O solvent, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 6.1 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 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 the product Nd(III)-based hydrogen-bonded organic framework crystalline material, with a yield of approximately 82.3%.

[0024] Example 5 This example provides a method for preparing a Nd(III)-based hydrogen-bonded organic framework crystalline material.

[0025] S1. Add 0.10 mmol of NdCl3·6H2O, 0.05 mmol of H2(4-CPCA), and 0.05 mmol of 1,10-phenanthroline to a glass scintillation vial containing 2 mL of H2O solvent, mix evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 6.3 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. 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 the product Nd(III)-based hydrogen-bonded organic framework crystalline material, with a yield of approximately 81.6%.

[0026] Example 6 Take the final product Nd(III)-based hydrogen-bonded organic framework crystalline material prepared in Example 1 for characterization.

[0027] (1) Crystal structure determination of the Nd(III)-based hydrogen-bonded organic framework crystalline material Select a single crystal with dimensions of 0.20×0.11×0.05 under a microscope and carry out an X-ray diffraction experiment at room temperature.

[0028] Diffraction data were collected on a Bruker-Apex II X-ray single crystal diffractometer using Mo-Kα radiation (λ = 0.71073 Å) monochromatized by a graphite monochromator. Diffraction points were collected in the ω-2θ scan mode. All data were corrected for factors and empirical absorption. The crystal structure was solved by direct methods using a program, and hydrogen atoms were determined by difference Fourier synthesis and fixed at the calculated optimal positions. Using the SHELX-97 program, full-matrix least-squares refinement was performed on all non-hydrogen atoms and their anisotropic thermal parameters. The main crystallographic determination data of the Nd(III)-based hydrogen-bonded organic framework crystalline material are shown in Tables 1 and 2, and the important bond length and bond angle data of the Nd(III)-based hydrogen-bonded 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 hydrogen-bonded organic framework crystalline material is as Figure 2 shown.

[0029] Table 1

[0030] Table 2

[0031] In Table 1, a, b, and c represent the edge lengths of the crystal along the three crystallographic axes, and α, β, and γ represent the angles between the a and b, a and c, and b and c axes, respectively; Z Z is the number of molecules 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 consistency factor; R1 and wR2 are both weighted consistency factors; In Table 2, Nd1 in the first row refers to Nd atom 1 in the single crystal of the Nd(III)-based hydrogen-bonded organic framework crystalline material, O4 refers to O atom 4 in the single crystal of the Nd(III)-based hydrogen-bonded organic framework crystalline material, and Nd1-O4 represents the bond length between Nd atom 1 and O atom 4, with a bond length of 2.440 ± 2, where 2 is the standard deviation; O4-Nd1-O3 represents the bond angle between O atom 4, Nd atom 1, and O atom 3, with a bond angle of 76.30 ± 7; Figure 1 is the single molecule diagram of Product 1, Figure 2 is the three-dimensional supramolecular diagram of Product 1; The molecular formula of the Nd(III)-based hydrogen-bonded organic framework crystalline material is {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} n .

[0032] From Figure 1 and Figure 2It can be seen that the Nd(III)-based hydrogen-bonded organic framework crystalline material prepared in this example uses Nd(III) as the central metal ion, which coordinates with 9 oxygen atoms respectively. Adjacent Nd(III) are connected by H2(4-CPCA) ligands to form a one-dimensional chain structure. The one-dimensional chains are bridged by H2(4-CPCA) ligands to form a two-dimensional bilayer planar structure, and the two-dimensional planes are further stacked through a large number of intermolecular hydrogen bond interactions to form a three-dimensional supramolecular structure.

[0033] {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} n Crystallizes in the space group C2 / c and belongs to the monoclinic system. Its asymmetric structural unit includes 1 Nd 3+ , 1 deprotonated H2(4-CPCA) molecule, 1 hydrogen-depleted H2(4-CPCA) molecule, 3 monodentate coordinated H2O molecules and 1 free H2O molecule. The central metal ion Nd 3+ coordinates with 9 oxygen atoms, among which 4 oxygen atoms (O5, O6, O7, O9) come from the carboxyl and carbonyl groups in the chelating coordinated H2(4-CPCA), 2 oxygen atoms (O2, O3) come from the carboxyl group in the chelating coordinated H2(4-CPCA), and 3 oxygen atoms (O1, O4, O8) come from three monodentate coordinated H2O molecules. Along the a-axis direction, adjacent Nd 3+ are connected by H2(4-CPCA) ligands to form a one-dimensional chain structure. The one-dimensional chains are bridged by H2(4-CPCA) ligands to form a two-dimensional bilayer planar structure, and the two-dimensional planes are further stacked through a large number of intermolecular hydrogen bond interactions to form a three-dimensional supramolecular structure.

[0034] (2)Infrared (IR) spectrum characterization Figure 3 The IR spectra of the Nd(III)-based hydrogen-bonded organic framework crystalline material and H2(4-CPCA) are shown. The sample infrared spectrum data were collected in the range of 500 - 4000 cm -1 , using KBr pressing tablets. It can be seen from Figure 3 that the bending vibration peak of C-H in the benzene ring is at 1450 cm -1 , the stretching vibration peak of the C-H bond is at 2960 cm -1 , the stretching vibration peak of C=O is at 1655 cm -1 . The strong peak at 1601 cm -1 in H2(4-CPCA) accurately indicates the presence of C-N. Infrared spectroscopy studies show that the vibration peaks of -COO - and C=O shift to lower wavenumbers, indicating the existence of coordination between the ligand and the metal ion.

[0035] (3)Phase purity characterization of Nd(III)-based hydrogen-bonded organic framework crystalline materials The powder XRD characterization results of Nd(III)-based hydrogen-bonded organic framework crystalline materials using a Bruker / D8 Advance X-ray diffractometer show that they have reliable phase purity, as Figure 4 shown.

[0036] (4)Fluorescent sensing properties of Nd(III)-based hydrogen-bonded organic framework crystalline materials Since heavy metal ions are often distributed in water, it is more convenient to study the fluorescent sensing properties of Nd(III)-based hydrogen-bonded organic framework crystalline materials for Fe 3+ , La 3+ and Mn 2+ ions in aqueous solution.

[0037] The photoluminescence (PL) properties of Nd(III)-based hydrogen-bonded organic framework crystalline materials were studied at room temperature, and fluorescent sensing experiments were carried out in a DMA suspension. Figure 5 is the solid-state fluorescence spectrum of Nd(III)-based hydrogen-bonded organic framework crystalline materials. It can be seen from Figure 5 that the maximum emission peak of Nd(III)-based hydrogen-bonded organic framework crystalline materials is 424 nm.

[0038] 2 mg of the Nd(III)-based hydrogen-bonded organic framework crystalline material powder sample was immersed in 4 mL of DMA and dissolved, and then ultrasonically treated for 20 min to obtain a stable suspension. According to the above method, Na solutions with a concentration of 0.1 mol / L were prepared respectively + , K + , Pb 2 + , Cd 2+ , Zn 2+ , Mn 2+ , Ba 2+ , Hg 2+ , Ca 2+ , Co 2+ , Ag + , Ni 2+ , Cu 2+ , Eu 3+ , Sm 3+ , Nd 3+ , Gd 3+ , Pr 3+ , Dy 3+ , La 3+ , Ho 3 + , Lu 3+Metal cations such as and tetracycline, ascorbic acid, and dopamine suspension solutions are used for qualitative and anti-interference studies. Each time, 3 μL of the above-prepared suspension solution is used for quantitative titration studies, and the fluorescence spectrum is recorded and collected under excitation at a wavelength of 378 nm.

[0039] For the Nd(III)-based hydrogen-bonded organic framework crystalline material, at an excitation wavelength of 378 nm, the corresponding fluorescence emission intensity is as Figure 6 shown. Comparing the changes in luminescence intensity caused by each metal ion, with the addition of Fe 3+ , La 3+ and Mn 2+ ions, a fluorescence quenching effect occurs.

[0040] To study the ability of the Nd(III)-based hydrogen-bonded organic framework crystalline material as a fluorescence probe to detect Fe 3+ , La 3+ and Mn 2 + , based on the obtained experimental data, further analysis is carried out. Figure 6 This is the fluorescence spectrum of the Nd(III)-based hydrogen-bonded organic framework crystalline material after adding different volumes of Fe 3+ solution (0.1 mmol / L). Figure 7 This is the linear fitting graph of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in the Fe 3+ solution. It can be seen from Figure 6 and Figure 7 that the fluorescence intensity of the Nd(III)-based hydrogen-bonded organic framework crystalline material at a wavelength of 424 nm decreases with the increase in the concentration of Fe 3+ ions, and shows a good linear relationship in a certain concentration range (R 2 = 0.9907).

[0041] Figure 8 This is the fluorescence spectrum of the Nd(III)-based hydrogen-bonded organic framework crystalline material after adding different volumes of La 3+ solution (0.1 mmol / L). With the increase in the concentration of La 3+ , the fluorescence intensity of the hydrogen-bonded organic framework crystalline material gradually weakens.

[0042] Figure 9 This is the linear fitting graph of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in the La 3+ solution; according to the Stern-Volmer equation (I0 - I) / I = K sv φ (I0 and I are the fluorescence intensities before and after adding La 3+ respectively, φ is the volume fraction of La 3+ , and K sv(where \(k_q\) is the quenching constant), the linear correlation coefficient \(R\) was obtained by fitting 2 = 0.9996.

[0043] Figure 10 Figure 2+ shows the fluorescence spectra of the Nd(III)-based hydrogen-bonded organic framework crystalline material after adding different volumes of Mn 2+ solution (0.1 mmol / L). Figure 11 Figure 2+ is the linear fitting diagram of the fluorescence change value of the Nd(III)-based hydrogen-bonded organic framework crystalline material in the Mn 2+ solution. It can be seen from Figure 10 and Figure 11 that the fluorescence intensity of the Nd(III)-based hydrogen-bonded organic framework crystalline material at 424 nm wavelength gradually weakens with the increase of the Mn 2+ concentration. And there is a good linear relationship in a certain concentration range (\(R\) 2 = 0.9985).

[0044] 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 \(3\sigma / K\) sv . (where \(\sigma\) is the standard deviation value of the fluorescence intensity of 11 blank experiments of the test complex without adding any ions). Calculated from the limit of detection formula: The limit of detection of the Nd(III)-based hydrogen-bonded organic framework crystalline material for Fe 3+ is: \(1.74\times10\) -4 \(mol\cdot L\) -1 , for La 3+ is: \(1.88\times10\) -4 \(mol\cdot L\) -1 , for Mn 2+ is: \(3.57\times10\) -4 \(mol\cdot L\) -1 . Compared with the fluorescence sensors of other hydrogen-bonded organic framework crystalline materials, the Nd(III)-based hydrogen-bonded organic framework crystalline material has a lower limit of detection and a wider linear detection range.

[0045] To further explore whether the Nd(III)-based hydrogen-bonded organic framework crystalline material can selectively detect Fe 3+ , La 3+ and Mn 2+ , Na + with a concentration of 0.1 mmol / L, K + , Cd 2 + , Zn 2+ , Ca 2+ , Co were added to the suspension of the Nd(III)-based hydrogen-bonded organic framework crystalline material.2+ 、Ag + 、Al 3+ 、Cu 2+ 、Eu 3+ 、Sc 3+ 、Nd 3+ 、Er 3+ 、Yb 3+ 、Sm 3+ 、Lu 3+ and other metal ions. After ultrasonic treatment to form a stable suspension, Nd(III)-based hydrogen-bonded 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 12 shown. It can be seen that even in the presence of other interfering metal ions, the Nd(III)-based hydrogen-bonded organic framework crystalline material can still selectively detect Fe 3+ 、La 3+ and Mn 2+ ions.

[0046] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modification, change, and equivalent change 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 Nd(III)-based hydrogen-bonded organic framework crystalline material, characterized in that The chemical formula of the Nd(III)-based hydrogen-bonded organic framework crystalline material is {Nd(H2O)3(4-CPCA)[H(4-CPCA)]∙H2O} n .

2. A method for preparing the Nd(III)-based hydrogen-bonded organic framework crystalline material as described in claim 1, characterized in that, It includes the following steps: S1. Add neodymium salt, H2(4-CPCA) and 1,10-phenanthroline into H2O, mix them evenly to obtain a mixed solution, adjust the pH value of the mixed solution to 5.2 - 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 a crystalline Nd(III)-based hydrogen-bonded organic framework material.

3. The preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material according to claim 2, wherein, 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)-based hydrogen-bonded organic framework crystalline material according to claim 2, wherein, H2(4-CPCA) described in S1 is 1-(4-carboxyphenyl-4-oxo-pyridazine)-3-carboxylic acid, and the structural formula of H2(4-CPCA) is: 。 5. The preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material according to claim 2, wherein, The molar ratio of the neodymium salt, H2(4-CPCA) and 1,10-phenanthroline described in S1 is 0.10 - 0.15 mmol: 0.05 - 0.10 mmol: 0.05 - 0.10 mmol, and the volume of H2O is 2 mL.

6. The preparation method of the Nd(III)-based hydrogen-bonded organic framework crystalline material according to claim 2, wherein, 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.

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

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

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