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

Abstract

The invention relates to the field of fluorescence sensing technology, and in particular to a Nd(III) metal organic framework crystalline material, its preparation method, and fluorescence sensing application. In the present invention, the Nd(III) metal organic framework crystalline material uses Nd(III) as the central metal ion, which is coordinated with 8 oxygen atoms to form a dodecahedral structure. Adjacent Nd(III) atoms are connected by [H(4-CPCA)2] 3‑ The bridging coordination forms a one-dimensional chain structure, which is then further stacked through intermolecular forces to form a three-dimensional framework structure. Nd(III) metal-organic framework crystalline materials have excellent fluorescence properties and stability, and can be used in 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 fluorescence sensing applications. Background Art

[0002] With the development of human production and the advancement of technology, the natural environment has also been harmed, especially the increasing number of 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 antibiotics have seriously affected human health and life. Therefore, under the current situation, the detection of pollutants has become an important issue in providing people with a good living environment. The commonly used methods for detecting substances 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., but these methods still have certain limitations.

[0003] Therefore, developing a highly sensitive, rapid, convenient, and low-cost method is essential and urgent. Rare earth elements can combine with organic ligands to form rare earth complexes. The diverse coordination numbers and frequent occurrence of unusual coordination geometries reflect the richness and uniqueness of rare earth coordination modes. Due to the unique electronic structure of rare earth elements and the "antenna effect" of the ligands, rare earth complexes possess spectral properties unmatched by conventional substances, including high color purity, stable luminescence, strong specificity, broad emission wavelengths, and long fluorescence lifetimes. In recent years, numerous rare earth complexes with excellent luminescence properties have been applied to the preparation of fluorescent sensors for detecting drugs, cations, anions, antibiotics, and temperature sensing. Consequently, fluorescence sensing based on rare earth complexes has gradually become an important research tool in fields such as chemistry, life sciences, basic medicine, and environmental monitoring. 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 thereof. The Nd(III) metal organic framework crystalline material is obtained by using a pyridazine carboxylic acid derivative H2(4-CPCA) as an organic ligand to coordinate with the rare earth metal neodymium. The chemical expression of the single molecule is {Nd[H(4-CPCA)2]} n , with Nd(III) as the central metal ion, it coordinates with 8 oxygen atoms to form a dodecahedral structure, and adjacent Nd(III) are connected by [H(4-CPCA)2] 3-The bridging coordination forms a one-dimensional chain structure, which is further stacked through intermolecular forces to form a three-dimensional skeleton structure. It has excellent fluorescence properties and stability and can be used in the field of fluorescence sensing.

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

[0006] The present invention also provides a method for preparing the above-mentioned Nd(III) metal organic framework crystalline material, comprising the following steps:

[0007] S1. Adding neodymium salt and H2(4-CPCA) to H2O and mixing uniformly to obtain a mixed solution, adjusting the pH value of the mixed solution to 5.1-6.3, and reacting at a constant temperature to obtain a reaction product;

[0008] S2. Cooling the reaction product obtained in S1 to crystallize to obtain a crystallized product, and sequentially washing, filtering and drying the crystallized product to obtain a Nd(III) metal organic framework crystalline material.

[0009] According to the present invention, a method for preparing a Nd(III) metal organic framework crystalline material is provided, wherein the neodymium salt in S1 is either NdCl3·6H2O or Nd(NO3)3·6H2O, the temperature condition of the isothermal reaction is 110°C, and the time condition of the isothermal reaction is 48 h.

[0010] According to the preparation method of the Nd(III) metal organic framework crystalline material provided by the present invention, the H2(4-CPCA) in S1 is 1-(4-carboxyphenyl-4-oxopyridazine)-3-carboxylic acid, and the structural formula of the H2(4-CPCA) is:

[0011] .

[0012] According to the preparation method of the Nd(III) metal organic framework crystalline 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 the H2O is 2 mL.

[0013] According to the preparation method of the Nd(III) metal organic framework crystalline material provided by the present invention, 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.

[0014] According to the preparation method of the Nd(III) metal organic framework crystalline material provided by the present invention, the filtration in S2 is reduced pressure filtration, the drying temperature is 30° C., and the drying time is 3 h.

[0015] The present invention also provides an application of the above-mentioned Nd(III) metal organic framework crystalline material, wherein the Nd(III) metal organic framework crystalline material is applied to fluorescence sensing.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 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, it coordinates with 8 oxygen atoms to form a dodecahedral structure, and adjacent Nd(III) are connected by [H(4-CPCA)2] 3- The bridging coordination forms a one-dimensional chain structure, and the one-dimensional chains are further stacked to form a three-dimensional skeleton structure through intermolecular forces. n It has good fluorescence properties and stability and can be used in the field of fluorescence sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a single molecule image of Nd(III) metal organic framework crystalline material;

[0019] Figure 2 This is a three-dimensional supramolecular stacking diagram of Nd(III) metal organic framework crystalline material;

[0020] Figure 3 This is the IR spectrum of Nd(III) metal organic framework crystalline material;

[0021] Figure 4 This is the XRD pattern of Nd(III) metal organic framework crystalline material;

[0022] Figure 5 This is the solid-state fluorescence spectrum of Nd(III) metal-organic framework crystalline material;

[0023] Figure 6 The addition of different volumes of Pb into the Nd(III) metal organic framework crystalline material 2+ Fluorescence spectrum after solution (0.1mmol / L);

[0024] Figure 7 It is a Nd(III) metal organic framework crystalline material in Pb 2+ Linear fitting graph of fluorescence change values ​​in solution;

[0025] Figure 8 This is the fluorescence spectrum after adding different volumes of tetracycline solution (0.01mmol / L) into Nd(III) metal organic framework crystalline material;

[0026] Figure 9 This is the linear fitting diagram of the fluorescence change value of Nd(III) metal organic framework crystalline material in Tetracycline solution;

[0027] Figure 10 The Nd(III) metal organic framework crystalline material is Pb 2+ And the anti-interference effect of the specific changes in tetracycline fluorescence. DETAILED DESCRIPTION

[0028] Example 1

[0029] This embodiment provides a method for preparing a Nd(III) metal organic framework crystalline material.

[0030] S1. 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) were added to a glass scintillation vial containing 2 mL of H2O and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 5.3 with a 0.3 mol / L sodium hydroxide solution. The mixed solution was subjected to a solvothermal isothermal reaction at 110°C for 48 h to obtain a reaction product.

[0031] Wherein, H2(4-CPCA) is 1-(4-carboxyphenyl-4-oxopyridazine)-3-carboxylic acid, and the structural formula of H2(4-CPCA) is:

[0032] ;

[0033] S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallized product. Rinse the crystallized product with deionized water, and then filter it under reduced pressure to obtain transparent block crystals. Place the transparent block crystals in an oven at a temperature of 30° C. and dry them at a constant temperature for 3 h to obtain product 1, i.e., Nd(III) metal-organic framework crystalline material, with a yield of approximately 82.7%.

[0034] Example 2

[0035] This embodiment provides a method for preparing a Nd(III) metal organic framework crystalline material.

[0036] S1. 0.1 mmol of Nd(NO3)3·6H2O and 0.1 mmol of H2(4-CPCA) were added to a glass scintillation vial containing 2 mL of H2O and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 5.7 with a 0.3 mol / L sodium hydroxide solution. The mixed solution was subjected to a solvothermal isothermal reaction at 110°C for 48 h to obtain a reaction product.

[0037] S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallized product. Rinse the crystallized product with deionized water, and then filter it under reduced pressure to obtain transparent block crystals. Place the transparent block crystals in an oven at a temperature of 30° C. and dry them at a constant temperature for 3 h to obtain the product Nd(III) metal-organic framework crystalline material with a yield of approximately 83.6%.

[0038] Example 3

[0039] This embodiment provides a method for preparing a Nd(III) metal organic framework crystalline material.

[0040] S1. 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) were added to a glass scintillation vial containing 2 mL of H2O and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 5.9 with a 0.3 mol / L sodium hydroxide solution. The mixed solution was subjected to a solvothermal isothermal reaction at 110°C for 48 h to obtain a reaction product.

[0041] S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallized product. Rinse the crystallized product with deionized water, and then filter it under reduced pressure to obtain transparent block crystals. Place the transparent block crystals in an oven at a temperature of 30° C. and dry them at a constant temperature for 3 h to obtain the product Nd(III) metal-organic framework crystalline material with a yield of approximately 83.1%.

[0042] Example 4

[0043] This embodiment provides a method for preparing a Nd(III) metal organic framework crystalline material.

[0044] S1. 0.1 mmol of Nd(NO3)3·6H2O and 0.1 mmol of H2(4-CPCA) were added to a glass scintillation vial containing 2 mL of H2O and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 6.2 with a 0.3 mol / L sodium hydroxide solution. The mixed solution was subjected to a solvothermal isothermal reaction at 110°C for 48 h to obtain a reaction product.

[0045] S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallized product. Rinse the crystallized product with deionized water, and then filter it under reduced pressure to obtain transparent block crystals. Place the transparent block crystals in an oven at a temperature of 30° C. and dry them at a constant temperature for 3 h to obtain the product Nd(III) metal-organic framework crystalline material with a yield of approximately 83.5%.

[0046] Example 5

[0047] This embodiment provides a method for preparing a Nd(III) metal organic framework crystalline material.

[0048] S1. 0.1 mmol of NdCl3·6H2O and 0.1 mmol of H2(4-CPCA) were added to a glass scintillation vial containing 2 mL of H2O and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 6.3 with a 0.3 mol / L sodium hydroxide solution. The mixed solution was subjected to a solvothermal isothermal reaction at 110°C for 48 h to obtain a reaction product.

[0049] S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallized product. Rinse the crystallized product with deionized water, and then filter it under reduced pressure to obtain transparent block crystals. Place the transparent block crystals in an oven at a temperature of 30° C. and dry them at a constant temperature for 3 h to obtain the product Nd(III) metal-organic framework crystalline material with a yield of about 82.4%.

[0050] Example 6

[0051] The final product 1 prepared in Example 1, ie, the Nd(III) metal organic framework crystalline material, was characterized.

[0052] (1) Crystal structure determination of Nd(III) metal-organic framework crystalline materials

[0053] A single crystal with a size of 0.12×0.11×0.11 was selected under a microscope and X-ray diffraction experiments were carried out at room temperature.

[0054] Diffraction data were collected on a Bruker-ApexП X-ray single crystal diffractometer. Diffraction points were collected in ω-2θ scanning mode using Mo-Kα radiation (λ = 0.71073 Å) monochromated with a graphite monochromator. All data were corrected for factors and empirical absorption. The crystal structure was solved by a direct method using a program. Hydrogen atoms were determined by difference Fourier synthesis and fixed at the calculated optimal positions. All non-hydrogen atoms and their anisotropic thermal parameters were corrected by full-matrix least squares method using the SHELX-97 program. The main crystallographic measurement data of Nd(III) metal organic framework crystalline materials are shown in Tables 1 and 2. The important bond length and bond angle data of Nd(III) metal organic framework crystalline materials are shown in Table 2. The crystal structure is shown in Table 2. Figure 1 As shown, the three-dimensional supramolecular structure of metal organic framework crystalline materials is as follows Figure 2 shown.

[0055] Table 1

[0056]

[0057] Table 2

[0058]

[0059] Symmetric code: #1 x, y, z; #2 -x, y, -z+1 / 2; #3 x+1 / 2, y+1 / 2, z;

[0060] In Table 1, a, b, and c represent the edge lengths of the crystal in the directions of the three crystal axes, and α, β, and γ represent the angles between a and b, a and c, and b and c, respectively; Z is the number of molecules contained in the unit cell; the diffraction index range of the limiting factor is (h, k, l); F(000) is the number of electrons in the unit cell; Final 1 R indices [I>2σ(I)] is the residual factor R value for the observable diffraction point; R is the non-weighted consistency factor; R1 and wR2 are both weighted consistency factors;

[0061] In the first row of Table 2, Nd(1) refers to Nd atom 1 in the Nd(III) metal organic framework crystalline material single crystal, O(5) refers to O atom 5 in the Nd(III) metal organic framework crystalline material single crystal, Nd(1)-O(5) represents the bond length between Nd atom 1 and O atom 5, and its bond length is 2.422±2, with 2 being the standard deviation; O(5)-Nd(1)-O(2)#2 represents the bond angle between the two symmetrical atoms of O atom 5, Nd atom 1, and O atom 2, and its bond angle is 146.11±8;

[0062] Figure 1 is the single molecule image of product 1, Figure 2is 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 , namely Nd(III) metal organic framework crystalline material.

[0063] from Figure 1 and Figure 2 It can be seen that the Nd(III) metal organic framework crystalline material prepared in this embodiment is Nd 3+ As the central metal ion, it coordinates with 8 oxygen atoms to form a dodecahedral structure. The adjacent Nd(III) are connected by [H(4-CPCA)2] 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 skeleton structure.

[0064] Metal-organic framework crystalline material {Nd[H(4-CPCA)2]} n It crystallizes in space group C2 / c and belongs to the monoclinic system. Its asymmetric structural unit includes 1 Nd 3+ , 2 H (4-CPCA) that lost one hydrogen - . 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 chelate-coordinated H2(4-CPCA), and the other 4 oxygen atoms (O3, O5, O3, O5) come from the carboxyl groups on the chelate-coordinated H2(4-CPCA). Along the b-axis, it coordinates with 8 oxygen atoms to form a dodecahedral structure. Adjacent Nd(III) atoms are connected by [H(4-CPCA)2] 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 skeleton structure. Due to its good fluorescence properties and good stability, it can be used in the field of fluorescence sensing.

[0065] (2) Infrared (IR) spectrum characterization

[0066] Figure 3 This is the IR spectrum of Nd(III) metal organic framework crystalline material and H2(4-CPCA). The infrared spectrum of the sample was collected from 500 to 4000 cm -1 , using KBr pellets, Figure 3 It can be seen that 1510~1596cm -1 The three peaks between them are the stretching vibration peaks of the benzene ring, 1652 cm -1 The stretching vibration peak of carbonyl is at 1600 cm -1The strong peak at accurately indicates the presence of CN.

[0067] (3) Phase purity characterization of Nd(III) metal-organic framework crystalline materials

[0068] The powder XRD characterization results of Nd(III) metal organic framework crystalline materials using Bruker / D8Advance X-ray diffractometer showed that it has reliable phase purity, such as Figure 4 shown.

[0069] (4) Fluorescence sensing performance of Nd(III) metal-organic framework crystalline materials

[0070] Because heavy metal ions are often distributed in water, it is important to study the effect of Nd(III) metal organic framework crystalline materials on Pb 2+ , the fluorescence sensing performance of Tetracycline ions is more convenient.

[0071] The photoluminescence (PL) properties of Nd(III) metal organic framework crystalline materials were studied at room temperature, and fluorescence sensing experiments were carried out in aqueous suspension. Figure 5 This is the solid-state fluorescence spectrum of Nd(III) metal organic framework crystalline material. Figure 5 It can be seen that the maximum emission peak of the Nd(III) metal organic framework crystalline material is 423nm.

[0072] 2 mg of Nd(III) metal organic framework crystalline material powder sample was immersed in 4 mL of water to dissolve, and then ultrasonicated for 20 min to obtain a stable suspension. Na + , 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+ 、Gd 3+ 、Pr 3+ 、Dy 3+ 、La 3+ 、Ho 3+ 、Lu 3+The same metal cations and tetracycline, ascorbic acid and dopamine suspension solutions were used for qualitative and anti-interference studies. 3 μL of the above-prepared suspension solution was added each time for quantitative titration studies. The fluorescence spectra were recorded and collected under excitation at a wavelength of 378 nm.

[0073] The fluorescence emission intensity of Nd(III) metal organic framework crystalline material under the excitation wavelength of 378nm is as follows Figure 6 As shown in the figure, the changes in luminescence intensity caused by each metal ion are compared. 2+ The addition of Tetracycline causes fluorescence quenching effect.

[0074] In order to study the Nd(III) metal organic framework crystalline material as a fluorescent probe for the detection of Pb 2+ and Tetracycline, further analysis was conducted based on the experimental data obtained. Figure 6 The addition of different volumes of Pb into the Nd(III) metal organic framework crystalline material 2+ The fluorescence spectrum of the solution (0.1 mmol / L) after the Pb 2+ With the increase of concentration, the fluorescence intensity of the metal organic framework crystalline material gradually weakened. Figure 7 It is a Nd(III) metal organic framework crystalline material in Pb 2+ Linear fitting of fluorescence change values ​​in solution; according to the Stern-Volmer equation (I0-I) / I=K sv φ(I0 and I are respectively added Pb 2+ Fluorescence intensity before and after, φ is Pb 2+ Volume fraction, K sv is the quenching constant) and its linear correlation coefficient R 2 =0.9995.

[0075] Figure 8 This is the fluorescence spectrum after adding different volumes of Tetracycline solution (0.01mmol / L) into Nd(III) metal organic framework crystalline material. Figure 9 This is the linear fitting diagram of the fluorescence change value of Nd(III) metal organic framework crystalline material in Tetracycline solution. Figure 8 and Figure 9 It can be seen that the fluorescence intensity of the Nd(III) metal organic framework crystalline material at 423 nm gradually decreases with the increase of Tetracycline concentration. And it forms a good linear relationship within a certain concentration range (R 2 =0.9958).

[0076] The limit of detection (LOD) is also an important indicator for measuring the strength of fluorescence detection. The limit of detection (LOD) can be calculated by the formula 3σ / K sv Calculated. (where σ is the standard deviation of the fluorescence intensity of 11 blank experiments without adding any ions to the test complex) Calculated by the detection limit formula: Nd (III) metal organic framework crystalline material for Pb 2+ The detection limit is: 4.86× 10 -4 mol·L -1 The detection limit for Tetracycline is 1.95 × 10 -5 mol·L -1 Compared with other MOF-based fluorescence sensors, Nd(III) MOF-based fluorescence sensors have lower detection limits and wider linear detection ranges.

[0077] In order to further explore whether Nd(III) metal organic framework crystalline materials can selectively detect Pb 2+ and Tetracycline, and Na with a concentration of 0.1 mmol / L was added to the Nd(III) metal organic framework crystalline material suspension. + , 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+ After ultrasonic treatment to form a stable suspension, Nd(III) metal organic framework crystalline material ions were added. Under room temperature conditions, the fluorescence emission spectrum was detected at an excitation wavelength of 378 nm. The results are as follows: Figure 10 As shown in the figure, 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.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a Nd(III) metal organic framework crystalline material, characterized in that: The following steps are involved: S1. Add 0.05-0.10 mmol of neodymium salt NdCl3·6H2O or Nd(NO3)3·6H2O and 0.05-0.10 mmol of H2(4-CPCA) to 2 mL of H2O and mix well to obtain a mixed solution. Adjust the pH value of the mixed solution to 5.1-6.3, and react at a constant temperature of 110°C for 48 h to obtain a reaction product. The H2(4-CPCA) is 1-(4-carboxyphenyl-4-oxopyridazine)-3-carboxylic acid, and the structural formula of the H2(4-CPCA) is: ； S2. Cooling the reaction product obtained in S1 to crystallize to obtain a crystallized product, and sequentially washing, filtering and drying the crystallized product to obtain a Nd(III) metal organic framework crystalline material.

2. The method for preparing the Nd(III) metal organic framework crystalline material according to claim 1, 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.

3. The method for preparing the Nd(III) metal organic framework crystalline material according to claim 1, characterized in that: The filtration in S2 is reduced-pressure filtration, the drying temperature is 30° C., and the drying time is 3 h.

4. A Nd(III) metal organic framework crystalline material prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The molecular formula of the Nd(III) metal organic framework crystalline material is C 24 H 14 N4O 10 Nd.

5. A use of the Nd(III) metal organic framework crystalline material as claimed in claim 4, characterized in that: The Nd(III) metal organic framework crystalline material is applied to fluorescence sensing of tetracycline.

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