A Zn(II)-based metal-organic framework crystalline material, its preparation method and application

Abstract

The present invention relates to the field of fluorescence sensing technology, and particularly to a Zn(II)-based metal-organic framework crystalline material, a preparation method thereof, and an application thereof. In the present invention, zinc chloride and H3(5-COIA) ligand are added to DMA, the pH is adjusted, and a Zn(II)-based metal-organic framework material with a novel structure is prepared by a solvothermal method. The preparation method has the advantages of convenient operation, high yield, good reproducibility, etc. The Zn(II)-based metal-organic framework material has strong fluorescence emission performance and good water stability, and has been studied for selectively and sensitively detecting La 3+ ions in aqueous solution, thereby further protecting human health and the environment from the harm of these pollutants.

Description

Technical Field

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

[0002] Metal-organic frameworks (MOFs) are organic-inorganic hybrid materials with a crystalline porous network structure formed by the coordination of metal ions and organic ligands. They combine the rigidity of inorganic materials with the flexibility of organic materials, showing great potential in attractive applications. So far, MOFs with high porosity, adjustable size, and controllable structure have been rapidly developed and have extensive applications in the fields of separation, catalysis, energy, biomedicine, and sensing.

[0003] A sensor is a device that can perform simple, rapid, selective, and sensitive detection. As an ideal sensing material, it should be stable, highly sensitive to the target analyte, and not interfered by other possible substances. MOFs have great tunability and functionalization potential. By changing the metal ions and organic ligands, the porosity and composition of MOFs can be adjusted, thereby changing their luminescence and chemical-physical properties.

[0004] La 3+ is a transition metal ion that can be used in radiotherapy applications, catalysis, and the synthesis of nanomaterials. In addition, due to its equal size, La 3+ strongly binds to the Ca 2+ binding sites in proteins. Due to the increasing use of lanthanum compounds in industry, their emissions into the environment pose a greater threat to life. Therefore, the accurate determination of La 3+ is of great significance for human health and environmental monitoring. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a Zn(II)-based metal-organic framework crystalline material, a preparation method thereof, and an application thereof in view of the deficiencies of the above-mentioned prior art. The space group of the Zn(II)-based metal-organic framework crystalline material is P-1, belonging to the triclinic system. The smallest asymmetric unit consists of three Zn(II) ions, two deprotonated 5-COIA 3- ligands, and four monodentate coordinated water molecules. Zn1 is six-coordinated with two oxygen atoms of two monodentate coordinated water molecules and four oxygen atoms from four 5-COIA 3- ligands. Zn2 is coordinated with the oxygen in one monodentate coordinated water molecule and three 5-COIA 3-The oxygen atom of the ligand is hexacoordinated with the N atom on one pyridazine ring, and Zn3 is coordinated with the oxygen in a monodentate coordinated water molecule and two 5-COIA 3- The oxygen atom of the ligand is pentacoordinated with the N atom on one pyridazine ring. Each independent Zn2 and Zn3 has the same connection mode and is both connected through 5-COIA 3- ligand. Zn2 and Zn3 are connected through 5-COIA 3- Two carboxyl oxygen atoms on the benzene ring of the ligand are coordinated to form a one-dimensional chain, and Zn3 and Zn2 between the chains are linked through Zn1 to form a two-dimensional plane.

[0006] The present invention provides a Zn(II)-based metal-organic framework crystalline material, and the chemical expression of the Zn(II)-based metal-organic framework crystalline material is [Zn3(H2O)4(5-COIA)2] n , and the molecular formula of the Zn(II)-based metal-organic framework crystalline material is C 26 H 18 N4O 18 Zn3.

[0007] The present invention provides a preparation method of the above-mentioned Zn(II)-based metal-organic framework crystalline material, including the following steps:

[0008] S1. Add zinc chloride and H3(5-COIA) to DMA to obtain a mixed solution. After adjusting the pH value of the mixed solution to 3.6 - 4.2, fully react at a temperature of 90 - 95 °C to obtain a primary product;

[0009] S2. Cool the primary product prepared in S1 for crystallization, and wash, filter, and dry the precipitated crystals in sequence to obtain the Zn(II)-based metal-organic framework crystalline material.

[0010] According to the preparation method of the Zn(II)-based metal-organic framework crystalline material provided by the present invention, in S1, the molar volume ratio of zinc chloride, H3(5-COIA), and DMA is 0.4 mmol: 0.1 mmol: 2 mL, and the time for the full reaction is 50 - 54 h.

[0011] According to the preparation method of the Zn(II)-based metal-organic framework crystalline material provided by the present invention, in S2, the rinsing agent for rinsing is deionized water, the filtration is vacuum filtration, and the drying is constant temperature drying in an oven at 40 °C for 3 - 5 h.

[0012] The present invention also provides an application of the above-mentioned Zn(II)-based metal-organic framework crystalline material, and the Zn(II)-based metal-organic framework crystalline material is used to selectively and sensitively detect La 3+ ions in aqueous solution.

[0013] [Zn3(H2O)4(5-COIA)2] n The minimum asymmetric unit consists of three Zn(II) ions, two deprotonated 5-COIA 3- ligands and four monodentate coordinated water molecules. Zn1 is hexacoordinated with two oxygen atoms of two monodentate coordinated water molecules and four oxygen atoms from four 5-COIA 3- ligands. Zn2 is hexacoordinated with the oxygen in a monodentate coordinated water molecule, oxygen atoms from three 5-COIA 3- ligands and an N atom on a pyridazine ring. Zn3 is pentacoordinated with the oxygen in a monodentate coordinated water molecule, oxygen atoms of two 5-COIA 3- ligands and an N atom on a pyridazine ring. Each independent Zn2 and Zn3 has the same connection mode and is connected by 5-COIA 3- ligands. Between Zn2 and Zn3, they are coordinated by two carboxyl oxygen atoms on the benzene ring of 5-COIA 3- to form a one-dimensional chain. Between the chains, Zn3 and Zn2 are linked by Zn1 to form a two-dimensional plane. This crystalline Zn(II)-based metal-organic framework material belongs to the triclinic system, space group P-1, with unit cell parameters a = 8.0250(14) Å, b = 15.965(2) Å, c = 17.301(3) Å, α = 66.649(5)°, β = 82.852(9)°, γ = 75.924(7)°, V = 1973.0(5) Å 3 .

[0014] The present invention has the following advantages compared with the prior art:

[0015] (1) The present invention uses a one-pot solvothermal reaction to prepare the crystalline Zn(II)-based metal-organic framework material [Zn3(H2O)4(5-COIA)2] n , and this preparation method has the advantages of simple process, convenient operation, high yield, good reproducibility, etc.

[0016] (2) The crystalline Zn(II)-based metal-organic framework material in the present invention has strong fluorescence emission performance and good water stability, and has been studied for selectively and sensitively detecting La 3+ ions in aqueous solution, thereby further protecting human health and the environment from the harm of these pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the single molecule diagram of the crystalline Zn(II)-based metal-organic framework material prepared in Example 2;

[0018] Figure 2It is the three-dimensional supramolecular structure diagram of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2;

[0019] Figure 3 It is the IR diagram of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2;

[0020] Figure 4 It is the XRD diagram of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2;

[0021] Figure 5 It is the fluorescence enhancement diagram of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2;

[0022] Figure 6 It is the fitting diagram of the fluorescence change value of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2;

[0023] Figure 7 It is the anti-interference diagram of other ions of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2. Detailed implementation manners

[0024] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with specific embodiments.

[0025] The present invention provides a preparation method of a Zn(II)-based metal-organic framework crystalline material, which specifically includes the following steps:

[0026] S1. Add 0.4 mmol of zinc chloride and 0.1 mmol of H3(5-COIA) to 2 mL of DMA (dimethylacetamide) to obtain a mixed solution. After adjusting the pH value of the mixed solution to 3.6 - 4.2, perform a solvothermal reaction in a glass scintillation vial at a temperature of 90 - 95 °C for 50 - 54 h to obtain an intermediate product;

[0027] S2. Naturally cool the intermediate product prepared in S1 for crystallization. Wash the precipitated crystals with deionized water and perform vacuum filtration in sequence to obtain transparent block-shaped crystals, and then place them in an oven at a temperature of 40 °C for constant-temperature drying for 3 - 5 h to obtain the Zn(II)-based metal-organic framework crystalline material [Zn3(H2O)4(5-COIA)2] n .

[0028] The preparation method provided by the present invention has the advantages of convenient operation, high yield, good reproducibility, etc. The Zn(II)-based metal-organic framework crystalline material prepared has strong solid fluorescence emission performance and good water stability, and has been studied for selectively and sensitively detecting La in aqueous solution 3+ions, thereby further protecting human health and the environment from the harm of these pollutants.

[0029] Example 1

[0030] This example provides a method for preparing a Zn(II)-based metal-organic framework crystalline material, and the specific steps are as follows:

[0031] S1. Add 0.4 mmol of zinc chloride and 0.1 mmol of H3(5-COIA) to 2 mL of DMA (dimethylacetamide) to obtain a mixed solution, and adjust the pH value of the mixed solution to 3.6 with a 0.3 mol / L nitric acid solution. Carry out a solvothermal reaction in a glass scintillation vial at a temperature of 90 °C for 54 h to obtain an intermediate product;

[0032] S2. Naturally cool the intermediate product prepared in S1 for crystallization. Wash the precipitated crystals with deionized water and filter them under reduced pressure to obtain transparent block-shaped crystals. Then place them in an oven at a temperature of 40 °C for constant-temperature drying for 3 h to obtain the Zn(II)-based metal-organic framework crystalline material, and the yield is 76.4%.

[0033] Example 2

[0034] This example provides a method for preparing a Zn(II)-based metal-organic framework crystalline material, and the specific steps are as follows:

[0035] S1. Add 0.4 mmol of zinc chloride and 0.1 mmol of H3(5-COIA) to 2 mL of DMA (dimethylacetamide) to obtain a mixed solution, and adjust the pH value of the mixed solution to 3.8 with a 0.3 mol / L nitric acid solution. Carry out a solvothermal reaction in a glass scintillation vial at a temperature of 93 °C for 52 h to obtain an intermediate product;

[0036] S2. Naturally cool the intermediate product prepared in S1 for crystallization. Wash the precipitated crystals with deionized water and filter them under reduced pressure to obtain transparent block-shaped crystals. Then place them in an oven at a temperature of 40 °C for constant-temperature drying for 3 h to obtain the Zn(II)-based metal-organic framework crystalline material, and the yield is 79.5%.

[0037] Example 3

[0038] This example provides a method for preparing a Zn(II)-based metal-organic framework crystalline material, and the specific steps are as follows:

[0039] S1. Add 0.4 mmol of zinc chloride and 0.1 mmol of H3(5 - COIA) into 2 mL of DMA (dimethylacetamide) to obtain a mixed solution. Adjust the pH value of the mixed solution to 4.2 with a 0.3 mol / L nitric acid solution, and carry out a solvothermal reaction in a glass scintillation vial at 95 °C for 50 h to obtain an intermediate product.

[0040] S2. Naturally cool the intermediate product prepared in S1 for crystallization. Wash the precipitated crystals successively with deionized water and carry out vacuum filtration to obtain transparent block crystals, and then place them in an oven at 40 °C for constant temperature drying for 3 h to obtain the Zn(II)-based metal-organic framework crystalline material with a yield of 77.3%.

[0041] Example 4

[0042] Take the Zn(II)-based metal-organic framework crystalline material prepared in Example 1 for characterization, specifically as follows:

[0043] ① Determination of the crystal structure of the coordination polymer:

[0044] Select a single crystal with a suitable size of 0.200×0.230×0.250 mm under a microscope to conduct an X-ray diffraction experiment at room temperature. 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, and collect diffraction points in the ω-2θ scanning mode. All data are corrected by factors and empirical absorption. The crystal structure is solved by the direct method using a program, and hydrogen atoms are determined by difference Fourier synthesis and fixed at the calculated optimal positions. Using the SHELX-97 program, a full matrix least squares refinement based on all non-hydrogen atoms and their anisotropic thermal parameters is carried out. The detailed crystal determination data are shown in Table 1, and the important bond length and bond angle data are shown in Table 2. The crystal structure is as Figure 1 shown. Observing the three-dimensional supramolecular structure of the polymer from the c-axis direction, obvious molecular pores can be seen, as Figure 2 shown.

[0045] Table 1 Main crystallographic data of the Zn(II)-based metal-organic framework crystalline material

[0046]

[0047] Table 2 Important bond lengths (Å) and bond angles (°) of the Zn(II)-based metal-organic framework crystalline material

[0048]

[0049] 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 a and b, a and c, and b and c axes, 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 R indices I >2σ( I )] is the residual factor R value for observable diffraction points; R is the non-weighted goodness-of-fit factor; R1 and wR2 are both weighted goodness-of-fit factors;

[0050] In Table 2, Zn(1) in the first row refers to Zn atom 1 in the single crystal of the Zn(II)-based metal-organic framework crystalline material, N(1) refers to N atom 1 in the single crystal of the Zn(II)-based metal-organic framework crystalline material, and Zn(1)-N(1) represents the bond length between Zn atom 1 and N atom 1, and its bond length is 2.431 ± 9, where 9 is the standard deviation;

[0051] O(2)-Zn(1)-N(2) represents the bond angle between O atom 2, Zn atom 1, and N atom 2, and its bond angle is 70.8 ± 3;

[0052] Each minimal asymmetric unit consists of three Zn(II) ions, two deprotonated 5-COIA 3- ligands and four monodentate coordinated water molecules. Zn1 is hexacoordinated with two oxygen atoms of two monodentate coordinated water molecules and four oxygen atoms from four 5-COIA 3- ligands. Zn2 is hexacoordinated with the oxygen in one monodentate coordinated water molecule, the oxygen atoms from three 5-COIA 3- ligands, and the N atom on one pyridazine ring. Zn3 is pentacoordinated with the oxygen in one monodentate coordinated water molecule, the oxygen atoms of two 5-COIA 3- ligands, and the N atom on one pyridazine ring. Each independent Zn2 and Zn3 has the same connection mode and is connected through 5-COIA 3- ligands. Zn2 and Zn3 are coordinated through two carboxylate oxygen atoms on the benzene ring of 5-COIA 3- ligands to form a one-dimensional chain. The Zn3 and Zn2 between the chains are linked through Zn1 to form a two-dimensional plane. The crystal of this Zn(II)-based metal-organic framework crystalline material belongs to the triclinic system, space group P-1, and the unit cell parameters are a = 8.0250(14) Å, b = 15.965(2) Å, c = 17.301(3) Å, α = 66.649(5)°, β = 82.852(9)°, γ = 75.924(7)°, V = 1973.0(5) Å 3 .

[0053] ②IR spectrum characterization:

[0054] Figure 3 This is the IR spectrum of the Zn(II)-based metal-organic framework crystalline material. The infrared spectrum data of the sample were collected in the range of 500 - 4000 cm -1 , using the KBr pellet method. From Figure 3 , it can be seen that the peaks between 1401 - 1631 cm -1 are the stretching vibration peaks of the benzene ring, and the peak at 3127 cm -1 is the stretching vibration peak of the O-H bond in water molecules.

[0055] The molecular formula of the Zn(II)-based metal-organic framework crystalline material prepared in Example 2 is [Zn3(H2O)4(5-COIA)2] n , where n ranges from 10 12 to 10 18 .

[0056] ③ Phase purity characterization of the Zn(II)-based metal-organic framework crystalline material:

[0057] Using a Bruker / D8 Advance X-ray diffractometer, the powder XRD characterization results of the Zn(II)-based metal-organic framework crystalline material show its reliable phase purity, providing a guarantee for its application as a catalyst, as Figure 4 shown.

[0058] ④ Fluorescent sensing characterization of the Zn(II)-based metal-organic framework crystalline material

[0059] La 3+ was added in gradients and uniformly dispersed in the aqueous solution of the Zn(II)-based metal-organic framework crystalline material. As Figure 5 shown, with the increase of the La 3+ concentration, the fluorescence emission intensity of the Zn(II)-based metal-organic framework crystalline material at 530 nm increased significantly. As Figure 6 shown, there is a good linear relationship between the fluorescence intensity of the Zn(II)-based metal-organic framework crystalline material for fluorescent sensing and the La 3+ concentration (R 2 = 0.9995). Meanwhile, the fluorescence changes of the Zn(II)-based metal-organic framework crystalline material in the presence of 13 interfering ions were evaluated. As Figure 7 shown, the fluorescence intensity of the Zn(II)-based metal-organic framework crystalline material in the interfering ions is almost the same as that when La 3+ exists alone. The results show that La 3+ ions in the aqueous solution of mixed metal ions can be effectively detected.

[0060] 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 based on the technical essence of the invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A Zn(II)-based metal-organic framework crystalline material, characterized in that The chemical formula of the Zn(II)-based metal-organic framework crystalline material is [Zn3(H2O)4(5-COIA)2] n , and the molecular formula of the Zn(II)-based metal-organic framework crystalline material is C 26 H 18 N4O 18 Zn3. The Zn(II)-based metal-organic framework crystalline material is triclinic, the space group of the Zn(II)-based metal-organic framework crystalline material is P-1, and the unit cell parameters of the Zn(II)-based metal-organic framework crystalline material are a = 8.0250(14) Å, b = 15.965(2) Å, c = 17.301(3) Å, α = 66.649(5)°, β = 82.852(9)°, and γ = 75.924(7)°.

2. A method for preparing the Zn(II)-based metal-organic framework crystalline material as described in claim 1, characterized in that, It includes the following steps: S1. Add 0.4 mmol of zinc chloride and 0.1 mmol of H3(5-COIA) into 2 mL of DMA to obtain a mixed solution. After adjusting the pH value of the mixed solution to 3.6 - 4.2, react fully at a temperature of 90 - 95 °C for 50 - 54 h to obtain a primary product; S2. Cool the primary product prepared in S1 for crystallization, and wash, filter and dry the precipitated crystals in sequence to obtain a Zn(II)-based metal-organic framework crystalline material.

3. The preparation method of the Zn(II)-based metal-organic framework crystalline material according to claim 2, characterized in that, The rinsing agent for rinsing in S2 is deionized water, the filtration is vacuum filtration, and the drying is constant-temperature drying in an oven at 40 °C for 3 - 5 h.

4. Use of the Zn(II)-based metal-organic framework crystalline material according to claim 1, characterized in that, The Zn(II)-based metal-organic framework crystalline material is used for selectively detecting La 3+ ions in an aqueous solution.

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