Cd (II)-based metal organic framework crystalline material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fluorescence sensing development, in particular to a Cd (II)-based metal organic framework crystalline material as well as a preparation method and application thereof. The chemical formula of the Cd (II)-based metal organic framework crystalline material is {[Cd3 (H2O) 2 (DMA) 2 (5-CMOIA) 2]. 6 / 5H2O} n, the organic framework material is characterized by an X-ray single crystal diffractometer, and the result shows that the organic framework material is crystallized in a triclinic system P-1 space group, the asymmetric unit of the organic framework material is composed of three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions, three Cd (II) ions and three The complex is composed of two deprotonated (5-CMOIA) 3-ligands, two coordinated DMA solvent molecules, two coordinated water molecules and six fifths of crystal water molecules. The solid fluorescence spectrum of the Cd (II)-based metal organic framework crystalline material is measured, the fluorescence response of the Cd (II)-based metal organic framework crystalline material to metal ions in a solution is explored, and the result shows that the Cd (II)-based metal organic framework crystalline material can effectively recognize Hg < 2 + > from different ions 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 development, and in particular to a Cd(II)-based metal organic framework crystalline material and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of industrialization, the pollution problem of heavy metal ions in water bodies has become increasingly serious. 3 ⁺、Copper(Cu 2 ⁺、Hg 2 Heavy metal ions such as Fe⁺ pose a serious threat to the ecological environment and human health due to their high toxicity, bioaccumulation and poor degradability. 3 ⁺Excessive doses can cause neurodegenerative diseases, Hg 2 Long-term exposure to ⁺ can cause kidney damage and nervous system disorders, while Cu 2 The imbalance of ⁺ is closely related to Alzheimer's disease. Therefore, the development of efficient, sensitive and selective heavy metal ion detection technology has important scientific significance and practical application value.

[0003] Traditional heavy metal detection methods, such as atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS) and electrochemical analysis, have high precision, but have limitations such as expensive instruments, complex operations, and cumbersome pretreatment. In contrast, fluorescence sensing technology has become a hot topic of research in recent years due to its advantages such as high sensitivity, real-time response, low cost and portability. However, existing fluorescence sensors still face challenges such as insufficient selectivity, weak anti-interference ability, and poor material stability. In particular, they are susceptible to interference from coexisting ions in complex water environments, which limits their practical applications.

[0004] Metal-Organic Frameworks (MOFs) are emerging porous crystalline materials that have great potential in the field of sensing due to their designable pore structure, high specific surface area and abundant active sites. MOFs form a periodic network through the coordination of metal nodes and organic ligands, and their fluorescence properties can be achieved through metal-ligand charge transfer (MLCT) or the luminescence properties of the ligands themselves. Cadmium (Cd)-based coordination polymers have unique d 10 The electronic configuration, high radiation luminescence efficiency and structural adjustability make it an ideal candidate for fluorescent sensing materials. The present invention constructs a Cd(II)-based metal organic framework crystalline material through the design and synthesis strategy of pyridazine derivative ligands, and at the same time uses the synergistic chelating effect of the ligands to achieve the heavy metal ion Hg 2+ Specific recognition of Hg in complex environments 2+ A new solution is provided for efficient monitoring of ionic pollutants. Summary of the invention

[0005] The present invention provides a Cd(II)-based metal organic framework crystalline material and a preparation method and application thereof, wherein a Cd(II)-based metal organic framework crystalline material is prepared, and the chemical formula thereof is {[Cd 3 (H 2 O) 2 (DMA) 2 (5-CMOIA) 2 ]·6 / 5H 2 O} n The asymmetric unit consists of three Cd(II) ions, two deprotonated (5-CMOIA) 3- The Cd(II)-based metal organic framework crystalline material is composed of a ligand, two coordinated DMA solvent molecules, two coordinated water molecules and six fifths of crystal water molecules. Along the a-axis, two crystallographically independent Cd(II) ions form a ring structure through six ligands, and the ring structure is connected and extended through the ligands to form a two-dimensional double-layer structure. Finally, a three-dimensional supramolecular structure is formed along the a-axis through intermolecular forces. The Cd(II)-based metal organic framework crystalline material has good dispersibility in solution and can effectively identify Hg from different ions. 2+ , which can be applied in the field of fluorescence sensing.

[0006] The present invention provides a Cd(II)-based metal organic framework crystalline material, wherein the chemical formula of the Cd(II)-based metal organic framework crystalline material is {[Cd 3 (H 2 O) 2 (DMA) 2 (5-CMOIA) 2 ]·6 / 5H 2 O} n .

[0007] The present invention also provides a method for preparing the above Cd(II)-based metal organic framework crystalline material, comprising the following steps: S1, cadmium salt, H 3 (5-CMOIA) is added to DMA to obtain a mixed solution, the pH value of the mixed solution is adjusted to 2.5-2.9, and the reaction product is fully reacted at a constant temperature; S2. Cooling the reaction product obtained in S1 for crystallization, and washing, filtering and drying the crystallized product in sequence to obtain a Cd(II)-based metal organic framework crystalline material.

[0008] According to the method for preparing a Cd(II)-based metal organic framework crystalline material provided by the present invention, the cadmium salt in S1 is any one of cadmium nitrate, cadmium sulfate and cadmium chloride.

[0009] According to the method for preparing a Cd(II)-based metal organic framework crystalline material provided by the present invention, the cadmium salt and H 3 The molar ratio of (5-CMOIA) was 0.50 mmol:0.15 mmol, and the amount of DMA solvent used was 2 mL.

[0010] According to the preparation method of the Cd(II)-based metal organic framework crystalline material provided by the present invention, the solution for adjusting the pH in S1 is a concentrated nitric acid solution, the concentration of the concentrated nitric acid solution is 8 mol / L, the temperature for the full reaction is 100°C, and the time for the full reaction is 40 h.

[0011] According to the method for preparing Cd(II)-based metal organic framework crystalline materials provided by the present invention, the filtration in S2 is reduced pressure filtration, and the drying condition is: constant temperature drying in an oven at 50° C. for 3 h.

[0012] The present invention also provides an application of the Cd(II)-based metal organic framework crystalline material, wherein the Cd(II)-based metal organic framework crystalline material is used for fluorescent identification of Hg 2+ ion.

[0013] H 3 (5-CMOIA) is 5-[3-carboxy-5-methyl-4-oxopyridazin-1(4H)-yl]isophthalic acid, H 3 The structural formula of (5-CMOIA) is: .

[0014] The Cd(II)-based metal organic framework crystalline material of the present invention has an asymmetric unit composed of three Cd(II) ions, two deprotonated (5-CMOIA) 3- The structure of the Cd(II) ion complex is composed of a ligand, two coordinated DMA solvent molecules, two coordinated water molecules and six fifths of crystal water molecules. Along the a-axis, two crystallographically independent Cd(II) ions form a ring structure through six ligands, and the ring structure is connected and extended through the ligands to form a two-dimensional double-layer structure. Finally, a three-dimensional supramolecular structure is formed along the a-axis through intermolecular forces.

[0015] The Cd(II)-based metal organic framework crystalline material of the present invention belongs to the triclinic system and the P-1 space group, and the unit cell parameters are a=8.0031(3) Å, b=8.2793(2) Å, c=16.6387(5) Å, α=93.4680(10)°, β=100.1400(10)°, γ=102.7780(10)°, V=1052.69(6) Å 3 .

[0016] Compared with the prior art, the present invention has the following advantages: 1. The present invention adopts a one-pot solvent thermal reaction method to prepare Cd(II)-based metal organic framework crystalline materials. The preparation method has the advantages of simple process, convenient operation, high yield and good reproducibility.

[0017] 2. The Cd(II)-based metal organic framework crystalline material of the present invention has good dispersibility in the solution and can effectively identify Hg from different ions. 2+ , which can be applied in the field of fluorescence sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a single molecule image of the Cd(II)-based metal organic framework crystalline material prepared in Example 2; Figure 2 is a two-dimensional double-layer structure diagram of the Cd(II)-based metal organic framework crystalline material prepared in Example 2; Figure 3 is a three-dimensional supramolecular structure diagram of the Cd(II)-based metal organic framework crystalline material prepared in Example 2; Figure 4 is the IR graph of the Cd(II)-based metal organic framework crystalline material measured in Example 5; Figure 5 is the XRD pattern of the Cd(II)-based metal organic framework crystalline material measured in Example 5; Figure 6 is a solid fluorescence spectrum of the Cd(II)-based metal organic framework crystalline material measured in Example 5; Figure 7 is the fluorescence spectra of the Cd(II)-based metal organic framework crystalline material in different solvents measured in Example 5; Figure 8 The Cd(II)-based metal organic framework crystalline material to Hg 2+ Interference plot of fluorescence intensity changes; Fig. 9 The Cd(II)-based metal organic framework crystalline material measured in Example 5 was added with 0.1 mol / L of Hg 2+ Fluorescence enhancement diagram after ion solution; Fig.10 The Cd(II)-based metal organic framework crystalline material measured in Example 5 was added with 0.1 mol / L of Hg 2+ Fluorescence enhancement fitting curve after ion solution. DETAILED DESCRIPTION

[0019] Example 1

[0020] This embodiment provides a H 3The preparation method of (5-CMOIA) comprises the following specific steps: S1. Add 25 g of the reactant 5-aminoisophthalic acid to a 250 mL single-mouth bottle, then add 200 mL of anhydrous ethanol, and stir to obtain reaction solution 1; add 25 mL of thionyl chloride dropwise, and the solution gradually becomes clear as thionyl chloride is added, and after a period of dropwise addition, it becomes a white turbid solution. After the dropwise addition is completed, reflux at 80 °C with stirring, react for 5 h, and after cooling to room temperature, a large amount of white solid precipitates, which is concentrated to obtain a white solid crude product; After concentration, add ethyl acetate to dissolve it and adjust the pH of the solution to neutral. Transfer the solution to a separatory funnel and let it stand for separation. Extract the aqueous phase three times, combine the organic phases, and then extract the combined organic phases with water. The aqueous phase flows out from the bottom and the organic phase is poured out from the mouth. Remove water from the separated organic phase, filter it with suction, and concentrate it to obtain white solid 5-aminoisophthalic acid diethyl ester; S2. Add 6 g (0.025 mol) of 5-aminoisophthalic acid diethyl ester to a 500 mL single-necked bottle, then add 100 ml of distilled water and stir. Add 30 mL of 40% concentrated hydrochloric acid dropwise under ice bath, then add NaNO 2 Solution (2.7 g NaNO 2 Dissolve in 50 mL distilled water) and add dropwise to obtain a yellow clear reaction solution 2; S3. Add 13.5 g of sodium acetate to a 1000 mL flask, dissolve it with 100 ml of distilled water, and then add 175 mL of anhydrous ethanol. Stir at 0 °C. After 25 min, add 10 g of ethyl propionyl acetate. Continue stirring for 20 min, then add reaction solution 2 dropwise. The solution gradually turns yellow. As the diazonium salt is added, a bright yellow solid precipitates. After 3 h, the reaction is completed to obtain a yellow turbid reaction solution 3. Filter and wash the filter cake until it is neutral to obtain a bright yellow filter cake. Dry at room temperature to obtain a bright yellow solid diethyl (E)-5-[2-(1-ethoxy-1,3-dioxaalkane-2-ylidene) hydrazide] isophthalate; S4. Add 10.5 g of diethyl (E)-5-[2-(1-ethoxy-1,3-dioxaalkane-2-ylidene) hydrazide] isophthalate to a 500 mL single-necked bottle, add 100 mL of toluene and dissolve by ultrasonication to obtain a yellow clear reaction solution 4. Add 4.3 g of DMF-DMA, the solution color turns dark purple, reflux at 90 °C, monitor by TLC, and the reaction ends after 12 h. Add appropriate amount of CH 2 Cl 2Dissolve, ultrasonicate to precipitate a white solid, reflux, stir, and stand for 10 h, filter, and wash the filter cake with petroleum ether to obtain a white-yellow solid 5-[3-(ethoxycarbonyl)-5-methyl-4-oxopyrazine-1(4H)-yl]isophthalate; S5. Add 9.5 g of 5-[3-(ethoxycarbonyl)-5-methyl-4-oxopyrazine-1(4H)-yl]isophthalic acid ester and 150 ml of distilled water to a 500 mL single-necked bottle, stir, add 6.2 g of sodium hydroxide, heat to 60°C, reflux to obtain a reddish brown solution reaction solution 5. The reaction is completed after 3 h, and the solution turns purple-red. Cool to room temperature, add 150 mL of distilled water to the reaction bottle, and adjust the pH of the solution to 2. Flesh-colored solid 5-[3-carboxy-5-methyl-4-oxopyridazine-1(4H)-yl]isophthalic acid precipitates in the solution. Filter with suction, wash the filter cake until it is neutral, and dry to obtain a flesh-colored powder.

[0021] Example 2 This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows: S1. Mix 0.50 mmol of cadmium nitrate tetrahydrate and 0.15 mmol of H 3 (5-CMOIA) was added to a glass scintillation vial containing 2 mL of DMA solvent and mixed evenly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 2.6 with a concentrated nitric acid solution with a concentration of 8 mol / L. The mixed solution was subjected to solvothermal isothermal reaction at 100 °C for 40 h to obtain a reaction product. S2. Cool the reaction product obtained in S1 to crystallize to obtain a crystallized product, rinse the crystallized product with deionized water, and then perform vacuum filtration to obtain transparent flaky crystals, place the transparent flaky crystals in an oven at a temperature of 50°C for 3 h to obtain a Cd(II)-based metal organic framework crystalline material. The chemical formula of the Cd(II)-based metal organic framework crystalline material is {[Cd 3 (H 2 O) 2 (DMA) 2 (5-CMOIA) 2 ]·6 / 5H 2 O} n , the yield is about 75.6%.

[0022] The Cd(II)-based metal organic framework crystalline material prepared in this example has an asymmetric unit composed of three Cd(II) ions, two deprotonated (5-CMOIA) 3-The structure of the Cd(II) ion complex is composed of a ligand, two coordinated DMA solvent molecules, two coordinated water molecules and six fifths of crystal water molecules. Along the a-axis, two crystallographically independent Cd(II) ions form a ring structure through six ligands, and the ring structure is connected and extended through the ligands to form a two-dimensional double-layer structure. Finally, a three-dimensional supramolecular structure is formed along the a-axis through intermolecular forces.

[0023] Example 3 This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows: S1, 0.50 mmol of cadmium sulfate, 0.15 mmol of H 3 (5-CMOIA) was added to a glass scintillation vial containing 2 mL of DMA solvent and mixed evenly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 2.8 with a concentrated nitric acid solution with a concentration of 8 mol / L. The mixed solution was subjected to solvothermal isothermal reaction at 100 °C for 40 h to obtain a reaction product. S2. Cool the reaction product obtained in S1 and crystallize it to obtain a crystallization product. Rinse the crystallization product with deionized water, and then filter it under reduced pressure to obtain transparent flaky crystals. Place the transparent flaky crystals in an oven at a temperature of 50°C for 3 h to obtain a Cd(II)-based metal organic framework crystalline material with a yield of about 71.4%.

[0024] Example 4 This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows: S1, 0.50 mmol of cadmium chloride, 0.15 mmol of H 3 (5-CMOIA) was added to a glass scintillation vial containing 2 mL of DMA solvent and mixed evenly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 2.7 with a concentrated nitric acid solution with a concentration of 8 mol / L. The mixed solution was subjected to solvothermal isothermal reaction at 100 °C for 40 h to obtain a reaction product. S2. The reaction product obtained in S1 is cooled and crystallized to obtain a crystallized product, the crystallized product is rinsed with deionized water, and then filtered under reduced pressure to obtain transparent flaky crystals, and the transparent flaky crystals are placed in an oven at a temperature of 50° C. for 3 h to obtain a Cd(II)-based metal organic framework crystalline material with a yield of about 72.5%.

[0025] Example 5 The Cd(II)-based metal organic framework crystalline material prepared in Example 2 was characterized.

[0026] (1) Crystal structure determination of Cd(II)-based metal-organic framework crystalline materials A single crystal with a size of 0.180×0.190×0.230 mm was selected under a microscope and X-ray diffraction experiments were carried out at room temperature.

[0027] 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 rays (λ = 0.71073 Å) monochromatized by a graphite monochromator. All data were corrected by 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 based on the full-matrix least squares method using the SHELX-97 program. The main crystallographic measurement data of Cd(II)-based metal-organic framework crystalline materials are shown in Table 1. The important bond length and bond angle data of Cd(II)-based metal-organic framework crystalline materials are shown in Table 2. The asymmetric unit is shown in Table 2. Figure 1 As shown, Figure 2 This is a two-dimensional double-layer structure diagram of Cd(II)-based metal organic framework crystalline material. The three-dimensional supramolecular structure is observed from the a-axis direction, such as Figure 3 shown.

[0028] Table 1

[0029] Table 2

[0030] In Table 1, a, b and c represent the edge lengths of the crystal in the directions of the three crystal axes, 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 R indices [I>2σ (I)] is the residual factor R value for the observable diffraction point; R is the non-weighted consistency factor; R 1 and wR 2 All are weight consistency factors; In the first row of Table 2, Cd1 refers to Cd atom 1 in the Cd(II)-based metal organic framework crystalline material single crystal, O8#1 refers to the symmetric atom 1 of O atom 8 in the Cd(II)-based metal organic framework crystalline material single crystal, and Cd1-O8#1 represents the bond length between Cd atom 1 and the symmetric atom 1 of O atom 8, and the bond length is 2.2138±17, with 17 being the standard deviation; O8#1- Cd1-O2 represents the bond angle between the symmetric atom 1 of O atom 8, Cd atom 1 and O atom 2, and its bond angle is 135.53±8; (2) Infrared (IR) spectrum characterization Figure 4 Cd(II)-based metal organic framework crystalline materials and H 3 IR spectrum of (5-CMOIA), the sample was pressed into KBr pellets, and the infrared spectrum data was collected at 4000-500 cm -1 ,Depend on Figure 4 It can be seen that at about 3600-3300 cm -1 The stretching vibration peak of -OH can be observed at 3 (5-CMOIA) carboxylate group (-COO - ) corresponds to the vibrations at 1420-1300 cm -1 Strong peak at.

[0031] (3) Phase purity characterization of Cd(II)-based metal-organic framework crystalline materials The powder XRD characterization of Cd(II)-based metal organic framework crystalline materials using Bruker / D8Advance X-ray diffractometer showed that the diffraction peak positions of the simulated data were highly consistent with the experimental data, further verifying the high phase purity of the samples. Figure 5 shown.

[0032] (4) Fluorescence sensing performance of Cd(II)-based metal-organic framework crystalline materials In order to evaluate the fluorescence sensing performance of Cd(II)-based metal organic framework crystalline materials, the solid-state photoluminescence (PL) characteristics of Cd(II)-based metal organic framework crystalline materials were studied at room temperature. Figure 6 2 mg of Cd(II)-based metal organic framework crystalline material powder sample was immersed in 4 mL of different solvents and ultrasonically dispersed for 20 min to make it a uniform suspension. The fluorescence spectrum of the Cd(II)-based metal organic framework crystalline material was tested, as shown in Figure 7 As shown, the results show that the Cd(II)-based metal organic framework crystalline material has the best fluorescence response in ethanol suspension.

[0033] Next, the metal ion fluorescence sensing experiment was carried out in ethanol solvent. 2 mg of the powder sample was immersed in 4 mL of ethanol solvent and ultrasonically dispersed for 20 min to make it a uniform suspension. 3+ 、Lu 3+ , Hg 2+ , Pb 2+ , Cu 2+ 、Co 2+ 、Al 3+ 、Ni 2+ 、Cd 2+ and K +The results showed that Cd(II)-based metal organic framework crystalline materials can specifically recognize Hg 2+ , and is not interfered by other ions, such as Figure 8 In addition, in the quantitative titration test, 3 μL of 0.1 mol / L Hg 2+ solution, with Hg 2+ With the increase of concentration, the emission intensity of Cd(II)-based metal organic framework crystalline materials increases sharply, such as Fig. 9 shown. Fig.10 Add 0.1 mol / L Hg to Cd(II)-based metal organic framework crystalline materials 2+ The fluorescence enhancement fitting curve after ion solution is observed. Fig. 9 and Fig.10 It can be seen that the fluorescence intensity of Cd(II)-based metal organic framework crystalline materials is similar to that of Hg 2+ The concentration showed a good linear relationship (R 2 =0.9933).

[0034] Experimental data show that the Cd(II)-based metal organic framework crystalline material has a strong affinity for metallic Hg 2+ The detection exhibits significant selective anti-interference characteristics, enabling high-precision Hg 2 ⁺Specific identification provides reliable guarantee.

[0035] The above 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 change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A Cd(II)-based metal organic framework crystalline material, characterized in that: The chemical formula of the Cd(II)-based metal organic framework crystalline material is {[Cd3(H2O)2(DMA)2(5-CMOIA)2]·6 / 5H2O} n .

2. A method for preparing a Cd(II)-based metal organic framework crystalline material as claimed in claim 1, characterized in that: The method comprises the following steps: S1. Add cadmium salt and H3(5-CMOIA) to DMA to obtain a mixed solution, adjust the pH value of the mixed solution to 2.5-2.9, and fully react the reaction product at a constant temperature; S2. Cooling the reaction product obtained in S1 for crystallization, and washing, filtering and drying the crystallized product in sequence to obtain a Cd(II)-based metal organic framework crystalline material.

3. The method for preparing a Cd(II)-based metal organic framework crystalline material according to claim 2, characterized in that: The cadmium salt described in S1 is any one of cadmium nitrate, cadmium sulfate and cadmium chloride.

4. The method for preparing a Cd(II)-based metal organic framework crystalline material according to claim 2, characterized in that: The molar ratio of the cadmium salt and H3(5-CMOIA) in S1 is 0.50 mmol:0.15 mmol, and the amount of DMA solvent used is 2 mL.

5. The method for preparing a Cd(II)-based metal organic framework crystalline material according to claim 2, characterized in that: The solution for adjusting the pH value in S1 is a concentrated nitric acid solution, the concentration of the concentrated nitric acid solution is 8 mol / L, the temperature for the full reaction is 100° C., and the time for the full reaction is 40 h.

6. The method for preparing a Cd(II)-based metal organic framework crystalline material according to claim 2, characterized in that: The filtration in S2 is reduced pressure filtration, and the drying condition is: constant temperature drying in an oven at 50°C for 3 h.

7. A use of the Cd(II)-based metal organic framework crystalline material as claimed in claim 1, characterized in that: The Cd(II)-based metal organic framework crystalline material is used for fluorescent recognition of Hg 2+ ion.

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