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

Abstract

The present invention relates to the field of fluorescence sensing technology, and in particular to a Cd(II)-based metal organic framework crystalline material, its preparation method, and its application. The present invention prepares a Cd(II)-based metal organic framework crystalline material, whose chemical formula is {[Cd3(H2O)2(DMA)2(5-CMOIA)2]·6 / 5H2O} n The organic framework material was characterized by X-ray single crystal diffractometry. The results showed that the organic framework material crystallized in the triclinic P-1 space group, and its asymmetric unit was composed of three Cd(II) ions, two deprotonated (5-CMOIA) 3‑ The present invention measured its solid fluorescence spectrum and explored its fluorescence response to metal ions in solution. The results showed that the Cd(II)-based metal organic framework crystalline material can effectively identify Hg from different ions. 2+ , which can be applied in 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, a preparation method and an 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 ⁺), mercury (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 difficulty in degradation. 3 ⁺Excessive amounts can cause neurodegenerative diseases, Hg 2 Long-term exposure to Cu⁺ can cause kidney damage and nervous system disorders, while 2 An 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, while highly accurate, suffer from limitations such as expensive instrumentation, complex operation, and tedious pretreatment. In contrast, fluorescence sensing technology, with its advantages of high sensitivity, real-time response, low cost, and portability, has become a research hotspot in recent years. However, existing fluorescence sensors still face challenges such as insufficient selectivity, weak anti-interference capabilities, and poor material stability. In particular, they are susceptible to interference from coexisting ions in complex aqueous environments, limiting their practical application.

[0004] Metal-Organic Frameworks (MOFs), as emerging porous crystalline materials, have shown 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. 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 radiant luminescence efficiency and structural adjustability make it an ideal candidate for fluorescent sensing materials. This 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+ It provides a new solution for the efficient monitoring of ionic pollutants. Summary of the Invention

[0005] The present invention provides a Cd(II)-based metal organic framework crystalline material and its preparation method and application. A Cd(II)-based metal organic framework crystalline material is prepared, and its chemical formula is {[Cd3(H2O)2(DMA)2(5-CMOIA)2]·6 / 5H2O} n , whose 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 a crystal water molecule. 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 by 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 {[Cd3(H2O)2(DMA)2(5-CMOIA)2]·6 / 5H2O} n .

[0007] The present invention also provides a method for preparing the above-mentioned Cd(II)-based metal organic framework crystalline material, comprising the following steps:

[0008] S1. Adding cadmium salt and H3(5-CMOIA) to DMA to obtain a mixed solution, adjusting the pH value of the mixed solution to 2.5-2.9, and fully reacting the reaction product at a constant temperature;

[0009] S2. Cooling the reaction product obtained in S1 to crystallize, and washing, filtering and drying the crystallized product in sequence to obtain a Cd(II)-based metal organic framework crystalline material.

[0010] According to the preparation method of the 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.

[0011] According to the preparation method of the Cd(II)-based metal organic framework crystalline material provided by the present invention, 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.

[0012] 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.

[0013] According to the preparation method of the Cd(II)-based metal organic framework crystalline material 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 a temperature of 50° C. for 3 h.

[0014] 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.

[0015] H3(5-CMOIA) is 5-[3-carboxy-5-methyl-4-oxopyridazin-1(4H)-yl]isophthalic acid. The structural formula of H3(5-CMOIA) is:

[0016] .

[0017] The asymmetric unit of the Cd(II)-based metal organic framework crystalline material of the present invention is composed of three Cd(II) ions, two deprotonated (5-CMOIA) 3- The structure consists of a ligand, two coordinated DMA solvent molecules, two coordinated water molecules, and six-fifths of a crystallographic water molecule. Along the a-axis, two crystallographically independent Cd(II) ions form a ring structure through the six ligands. This ring structure is then connected and extended by the ligands to form a two-dimensional bilayer structure. Finally, intermolecular forces form a three-dimensional supramolecular structure along the a-axis.

[0018] 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 .

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention adopts a one-pot solvent thermal reaction method to prepare Cd(II)-based metal organic framework crystalline materials. This preparation method has the advantages of simple process, convenient operation, high yield and good reproducibility.

[0021] 2. The Cd(II)-based metal organic framework crystalline material of the present invention has good dispersibility in 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

[0022] Figure 1 This is a single molecule image of the Cd(II)-based metal organic framework crystalline material prepared in Example 2;

[0023] Figure 2 is a two-dimensional double-layer structure diagram of the Cd(II)-based metal organic framework crystalline material prepared in Example 2;

[0024] Figure 3 is a three-dimensional supramolecular structure diagram of the Cd(II)-based metal organic framework crystalline material prepared in Example 2;

[0025] Figure 4 is the IR spectrum of the Cd(II)-based metal organic framework crystalline material measured in Example 5;

[0026] Figure 5 is the XRD pattern of the Cd(II)-based metal organic framework crystalline material measured in Example 5;

[0027] Figure 6 This is a solid-state fluorescence spectrum of the Cd(II)-based metal-organic framework crystalline material measured in Example 5;

[0028] Figure 7 1 is a fluorescence spectrum of the Cd(II)-based metal organic framework crystalline material in different solvents measured in Example 5;

[0029] Figure 8 The Cd(II)-based metal organic framework crystalline material to Hg 2+ Interference plot of fluorescence intensity changes;

[0030] Figure 9 The Cd(II)-based metal organic framework crystalline material measured in Example 5 was added with 0.1 mol / L Hg 2+ Fluorescence enhancement diagram after ion solution;

[0031] Figure 10 The Cd(II)-based metal organic framework crystalline material measured in Example 5 was added with 0.1 mol / L Hg 2+ Fluorescence enhancement fitting curve after ion solution. DETAILED DESCRIPTION

[0032] Example 1

[0033] This embodiment provides a method for preparing H3(5-CMOIA), and the specific steps are as follows:

[0034] S1. Add 25 g of the reactant 5-aminoisophthalic acid to a 250 mL single-necked flask, followed by 200 mL of anhydrous ethanol, and stir to obtain reaction solution 1. Add 25 mL of thionyl chloride dropwise. The solution gradually becomes clear with the addition of thionyl chloride, but after a period of addition, it becomes a white, turbid solution. After the addition is complete, reflux at 80°C with stirring for 5 h. After cooling to room temperature, a large amount of white solid precipitates, which is concentrated to obtain a crude white solid product.

[0035] 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 to separate. 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. The separated organic phase is dehydrated, filtered, and concentrated to obtain white solid diethyl 5-aminoisophthalate.

[0036] S2. Add 6 g (0.025 mol) of diethyl 5-aminoisophthalate to a 500 mL single-necked flask, followed by 100 mL of distilled water and stir. Add 30 mL of 40% concentrated hydrochloric acid dropwise under an ice bath, followed by a NaNO₂ solution (2.7 g of NaNO₂ dissolved in 50 mL of distilled water) dropwise to obtain a clear yellow reaction solution 2.

[0037] S3. Add 13.5 g of sodium acetate to a 1000 mL flask, dissolve it in 100 ml of distilled water, and then add 175 mL of anhydrous ethanol. Stir at 0°C. After 25 minutes, add 10 g of ethyl propionyl acetate. Continue stirring for 20 minutes, then add reaction solution 2 dropwise. The solution gradually turns yellow. As the diazonium salt is added, a bright yellow solid precipitates. The reaction is complete after 3 hours, yielding a yellow, turbid reaction solution 3. Filter and wash the filter cake until 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-dioxane-2-ylidene)hydrazide]isophthalate.

[0038] S4. Add 10.5 g of diethyl (E)-5-[2-(1-ethoxy-1,3-dioxane-2-ylidene)hydrazide]isophthalate to a 500 mL single-necked flask and dissolve in 100 mL of toluene by ultrasonication to obtain a yellow, clear reaction solution 4. Add 4.3 g of DMF-DMA, and the solution will turn dark purple. Reflux at 90°C and monitor with TLC. The reaction is complete after 12 h.

[0039] Add appropriate amount of CH2Cl2 to dissolve, ultrasonicate to precipitate a white solid, reflux, stir, and after 10 h, let it stand, filter with suction, and wash the filter cake with petroleum ether to obtain a white-yellow solid 5-[3-(ethoxycarbonyl)-5-methyl-4-oxopyrazin-1(4H)-yl]isophthalate;

[0040] 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 flask, stir, then 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 flask, 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.

[0041] Example 2

[0042] This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows:

[0043] S1. Add 0.50 mmol of cadmium nitrate tetrahydrate and 0.15 mmol of H3(5-CMOIA) into a glass scintillation vial containing 2 mL of DMA solvent and mix well to obtain a mixed solution. Adjust the pH value of the mixed solution to 2.6 with 8 mol / L concentrated nitric acid solution. The mixed solution is subjected to solvothermal reaction at 100°C for 40 h to obtain a reaction product.

[0044] S2. Cooling the reaction product obtained in S1 and performing crystallization to obtain a crystallized product, rinsing the crystallized product with deionized water, and then performing reduced pressure filtration to obtain transparent flaky crystals, placing the transparent flaky crystals in an oven at a temperature of 50° C. and maintaining the temperature 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 {[Cd3(H2O)2(DMA)2(5-CMOIA)2]·6 / 5H2O} n , the yield is about 75.6%.

[0045] The asymmetric unit of the Cd(II)-based metal organic framework crystalline material prepared in this example consists of three Cd(II) ions, two deprotonated (5-CMOIA) 3-The structure consists of a ligand, two coordinated DMA solvent molecules, two coordinated water molecules, and six-fifths of a crystallographic water molecule. Along the a-axis, two crystallographically independent Cd(II) ions form a ring structure through the six ligands. This ring structure is then connected and extended by the ligands to form a two-dimensional bilayer structure. Finally, intermolecular forces form a three-dimensional supramolecular structure along the a-axis.

[0046] Example 3

[0047] This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows:

[0048] S1. 0.50 mmol of cadmium sulfate and 0.15 mmol of H3(5-CMOIA) were added to a glass scintillation vial containing 2 mL of DMA solvent and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 2.8 with 8 mol / L concentrated nitric acid solution. The mixed solution was subjected to solvothermal isothermal reaction at 100°C for 40 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 flaky crystals. Place the transparent flaky crystals in an oven at a constant temperature of 50°C for 3 hours to obtain a Cd(II)-based metal-organic framework crystalline material with a yield of approximately 71.4%.

[0050] Example 4

[0051] This embodiment provides a method for preparing a Cd(II)-based metal organic framework crystalline material, and the specific steps are as follows:

[0052] S1. 0.50 mmol of cadmium chloride and 0.15 mmol of H3(5-CMOIA) were added to a glass scintillation vial containing 2 mL of DMA solvent and mixed uniformly to obtain a mixed solution. The pH value of the mixed solution was adjusted to 2.7 with 8 mol / L concentrated nitric acid solution. The mixed solution was subjected to solvothermal isothermal reaction at 100°C for 40 h to obtain a reaction product.

[0053] 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 flaky crystals. Place the transparent flaky crystals in an oven at a constant temperature of 50°C for 3 hours to obtain a Cd(II)-based metal-organic framework crystalline material with a yield of approximately 72.5%.

[0054] Example 5

[0055] The Cd(II)-based metal organic framework crystalline material prepared in Example 2 was characterized.

[0056] (1) Crystal structure determination of Cd(II)-based metal-organic framework crystalline materials

[0057] 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.

[0058] 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) monochromatized with 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 by 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. Its 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.

[0059] Table 1

[0060]

[0061] Table 2

[0062]

[0063] In Table 1, a, b, and c represent the edge lengths of the crystal in the directions of the three crystal axes, respectively; 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; R1 and wR2 are both weighted consistency factors;

[0064] 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, which is 2.2138±17, with 17 being the standard deviation;

[0065] 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;

[0066] (2) Infrared (IR) spectrum characterization

[0067] Figure 4 This is the IR spectrum of Cd(II)-based metal organic framework crystalline material and H3(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 - ) corresponds to the vibration of 1420-1300 cm -1 Strong peak at.

[0068] (3) Phase purity characterization of Cd(II)-based metal-organic framework crystalline materials

[0069] The powder XRD characterization of Cd(II)-based metal organic framework crystalline materials was carried out using a Bruker / D8Advance X-ray diffractometer. The results 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 sample. Figure 5 shown.

[0070] (4) Fluorescence sensing performance of Cd(II)-based metal-organic framework crystalline materials

[0071] 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 As shown. 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 into 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.

[0072] Next, the metal ion fluorescence sensing experiment was carried out in ethanol solvent. 2 mg of powder sample was immersed in 4 mL of ethanol solvent and ultrasonically dispersed for 20 min to make it into a uniform suspension. 3+ 、Lu 3+ 、Hg 2+ , Pb2+ 、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, along with Hg 2+ With the increase of concentration, the emission intensity of Cd(II)-based metal organic framework crystalline materials increases sharply, such as Figure 9 shown. Figure 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. Figure 9 and Figure 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).

[0073] Experimental data show that the Cd(II)-based metal organic framework crystalline material has a strong affinity for Hg 2+ The detection showed significant selective anti-interference characteristics, which enabled it to achieve high-precision Hg in mixed metal ion systems. 2 ⁺Specific recognition provides reliable guarantee.

[0074] 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 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 , wherein 5-CMOIA is H3(5-COIA) that has lost a hydrogen ion, the H3(5-COIA) is 1-(3, 5-dicarboxyphenyl)-4-oxo-1, 4-dihydropyridazine-3-carboxylic acid, the unit cell parameters of the Cd(II)-based metal organic framework crystalline material are a=8.0031(3) Å, b=8.2793(2) Å, c=16.6387(5) Å, α=93.4680(10) °, β=100.1400(10) ° and γ=102.7780(10) °, the space group of the Cd(II)-based metal organic framework crystalline material is P-1, the crystal system of the Cd(II)-based metal organic framework crystalline material is triclinic, and the structural formula of the H3(5-COIA) is: 。 2. A method for preparing a Cd(II)-based metal organic framework crystalline material according to claim 1, characterized in that: The method comprises the following steps: S1. Adding cadmium salt and H3(5-CMOIA) to DMA to obtain a mixed solution, adjusting the pH value of the mixed solution to 2.5-2.9, and reacting at a constant temperature of 100°C for 40 hours to obtain a reaction product; S2. Cooling the reaction product obtained in S1 to crystallize, 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, and the concentration of the concentrated nitric acid solution is 8 mol / L.

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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