Zinc-based porous coordination polymer for ethidene diamine fluorescence detection and preparation method and application of zinc-based porous coordination polymer

Abstract

The invention discloses a zinc-based porous coordination polymer for ethylenediamine fluorescence detection as well as a preparation method and application of the zinc-based porous coordination polymer. The chemical formula of the polymer is [Zn2 (2, 6-ndc) 2 (pvq)]. 4.5 DMF. 0.5 H2O, 2, 6-ndc < 2-> is a 2, 6-naphthalene dicarboxylic acid anion, pvq is a 5-(2-(pyridine-4-yl) vinyl) quinoline organic ligand, and the polymer belongs to a triclinic system and a P-1 space group. The polymer structure contains binuclear [Zn2 (COO) 4] paddle-wheel-shaped secondary building units, a square lattice network is formed through bridging of 2, 6-ndc2-ligand, a three-dimensional framework with pcu topology is formed through pvq ligand pillared, the three-dimensional framework is of a double interpenetrating structure, three-dimensional pore channels are formed, and the porosity is 50.2%. The preparation method comprises the following steps: mixing the raw materials, and carrying out solvothermal reaction at 90-120 DEG C for 12-24 hours to obtain the light yellow transparent square crystal. The polymer can be used for fluorescence sensing detection of ethylenediamine, specific recognition is realized through a fluorescence quenching effect, the response time is less than 15 seconds, and the detection limit is a micromole level.

Description

Technical Field

[0001] The present invention relates to the field of zinc-based porous coordination polymer materials, and in particular to a zinc-based porous coordination polymer for ethylenediamine fluorescence detection, a preparation method thereof, and applications thereof. Background Art

[0002] Ethylenediamine is an important organic compound widely used in the synthesis of pharmaceuticals, pesticides, dyes, resins, and other fields. However, it is also a toxic substance, posing a potential threat to human health and environmental safety. This colorless, volatile substance with a pungent odor can cause persistent damage to the liver, kidneys, and respiratory system after entering the body through inhalation or ingestion. Therefore, the development of efficient, sensitive, and highly selective methods for detecting ethylenediamine is of great significance.

[0003] Currently, conventional analytical methods for ethylenediamine detection primarily include high-performance liquid chromatography, gas chromatography-mass spectrometry, capillary electrophoresis, Raman spectroscopy, and electrochemical sensing. While these methods offer a certain degree of sensitivity and accuracy, they suffer from common shortcomings such as cumbersome experimental procedures, high equipment costs, the need for specialized operating techniques, and the difficulty in achieving real-time on-site detection, limiting their widespread adoption in practical applications.

[0004] In recent years, porous coordination polymers (PCPs) or metal-organic frameworks (MOFs) have shown broad application prospects in gas adsorption and separation, catalysis, and sensing due to their structural designability, pore controllability, and multifunctionality. In particular, fluorescent probes based on MOFs have attracted widespread attention due to their high sensitivity, rapid response, and visual detection capabilities.

[0005] For example, CN106749348B discloses a fluorescent metal-organic framework based on 2,6-naphthalenedicarboxylic acid. This material, synthesized using a solvothermal method, uses 2,6-naphthalenedicarboxylic acid as the primary ligand and p-aminotetrazolyl as the auxiliary ligand to create a doubly interpenetrating three-dimensional structure. This material can be used as a highly efficient fluorescent probe for detecting the explosive nitrobenzene. This material exhibits excellent chemical stability, high sensitivity, short reaction time, and high reusability, but it is primarily targeted at detecting nitrobenzene-based explosives and does not address the detection of ethylenediamine.

[0006] CN105017292A discloses a fluorescent probe for rapid identification of methanol molecules. The fluorescent probe is a coordination polymer with a chemical formula of C 39 H 25 N2O8Zn2, which crystallizes in the monoclinic system and has a C2 / c space group, is a fluorescent probe that can easily and quickly qualitatively identify methanol molecules and can be reused multiple times. However, its detection is limited to methanol and does not involve the detection of ethylenediamine.

[0007] CN117024769A discloses a three-dimensional porous Zn(II) mixed coordination polymer, the chemical formula of which is [Zn9(C 18 H18N6)6(C8H 10 O4)9], belonging to the orthorhombic system and Pnna space group. This coordination polymer has good stability and fluorescent properties, and is expected to be used as a fluorescent material, but it has not been specifically applied to the detection of ethylenediamine.

[0008] In summary, various fluorescent sensing materials based on porous coordination polymers have been reported in the prior art. However, these materials are primarily used for the detection of nitrobenzene explosives, metal ions, or simple organic molecules, lacking efficient and selective detection methods for ethylenediamine. Furthermore, existing ethylenediamine detection methods generally suffer from complex procedures, expensive equipment, and difficulty in achieving rapid on-site detection. Therefore, the development of a porous coordination polymer-based fluorescent sensing material for ethylenediamine that combines high sensitivity, excellent selectivity, ease of operation, and suitability for on-site detection has important scientific significance and application value. Summary of the Invention

[0009] The present invention aims to address the problems of the prior art by providing a zinc-based porous coordination polymer, its preparation method, and its application. This coordination polymer exhibits distinct blue fluorescence and can efficiently identify ethylenediamine through a specific fluorescence quenching effect. Based on this, the present invention further constructs a portable fluorescence sensing system that combines smartphone RGB analysis technology. This system enables rapid, highly selective, and highly sensitive visual detection of ethylenediamine, and has promising application prospects in the field of materials science.

[0010] The present invention is achieved through the following technical solutions: First, the present invention provides a zinc-based porous coordination polymer material, the chemical formula of which is: [Zn2(2,6-ndc)2(pvq)]·4.5DMF·0.5H2O, wherein 2,6-ndc 2- The anion of 2,6-naphthalene dicarboxylate is PVQ, the organic ligand is 5-(2-(pyridin-4-yl)vinyl)quinoline. The polymer material belongs to the triclinic system, the space group P-1, the unit cell parameters are a = 13.058(3) Å, b = 13.079(3) Å, c = 17.093(3) Å, α = 103.75(3)º, β = 96.51(3)º, γ = 92.31(3)º, and the unit cell volume V = 2810.4(10) Å. 3 .

[0011] Preferably, the polymer structure contains a binuclear [Zn2(COO)4] paddle wheel secondary building block, which is formed by 2,6-ndc 2- The ligands are bridged to form a square lattice network, which is connected by PVQ ligand pillars to form a three-dimensional framework structure with PCU topology. Two identical three-dimensional frameworks are interpenetrated to form a double interpenetrated structure with three-dimensional channels. The porosity calculated by Platon is 50.2%.

[0012] Secondly, the present invention also provides a method for preparing the above-mentioned zinc-based porous coordination polymer, comprising the following steps: (1) Add 2,6-naphthalene dicarboxylic acid, 5-(2-(pyridin-4-yl)vinyl)quinoline and zinc nitrate hexahydrate to -Mix evenly in dimethylformamide solvent; (2) The mixture obtained above was sealed and subjected to a solvothermal reaction at 90-120°C for 12-24 hours, and then naturally cooled to room temperature to obtain light yellow transparent square crystals; (3) Use The square crystals are washed with dimethylformamide and dried naturally to obtain the zinc-based porous coordination polymer.

[0013] Preferably, the molar ratio of 2,6-naphthalenedicarboxylic acid, zinc nitrate hexahydrate, and 5-(2-(pyridin-4-yl)vinyl)quinoline in step (1) is 1:1:0.5 to 1:1:1. The molar ratio can be adjusted arbitrarily within this range, for example, a molar ratio of 1:1:0.5, 1:1:0.8, or 1:1:1 can be selected. When the molar ratio is 1:1:0.5, the crystal morphology of the product is more regular, but the yield is slightly low; when the molar ratio is 1:1:1, the yield is higher, but the crystal size is relatively small.

[0014] Preferably, the molar volume ratio of the 2,6-naphthalenedicarboxylic acid to the solvent in step (1) is 0.1:3, expressed in mmol / mL.

[0015] Furthermore, the present invention also provides the application of the above-mentioned zinc-based porous coordination polymer in fluorescence sensing detection of ethylenediamine.

[0016] Preferably, the detection method is: disperse the polymer in -dimethylformamide to form a suspension, add the analyte to the suspension, and identify ethylenediamine through the fluorescence quenching effect.

[0017] Finally, the present invention also provides a portable ethylenediamine fluorescence sensing system, comprising: (i) The above-mentioned zinc-based porous coordination polymer is used as a sensing material; (ii) Smartphone RGB analysis platform; (iii) A visualization detection module based on fluorescence quenching response enables specific detection of ethylenediamine.

[0018] Preferably, the response time of the sensing system is less than 15 seconds, and the detection limit is at the micromolar level.

[0019] The beneficial effects of the present invention are: 1. The zinc-based porous coordination polymer material provided by the present invention exhibits a specific fluorescence quenching response to ethylenediamine, showing excellent selective recognition ability, which can effectively distinguish ethylenediamine from other similar molecules, solving the problem of insufficient selectivity of existing detection methods.

[0020] 2. The zinc-based porous coordination polymer material of the present invention has excellent fluorescence stability, a simple preparation process, a short reaction cycle, and easy product recovery. The crystal yield is greater than 40%, which greatly reduces the preparation cost and difficulty compared to the complex preparation process in the prior art.

[0021] 3. The zinc-based porous coordination polymer material of the present invention exhibits unique selective recognition ability for ethylenediamine molecules, with a response time of less than 15 seconds and a detection limit of 5.78μM, which is significantly lower than the detection limit of coordination polymer sensors reported in the literature (19.9μM), and has higher sensitivity.

[0022] 4. This portable fluorescence sensing system, built by combining smartphone RGB analysis technology, enables rapid, highly selective, and highly sensitive visual detection of ethylenediamine, with a detection limit of 9.97 μM. This portable smartphone-UV detection platform offers advantages such as ease of operation and rapid response, providing an efficient and reliable solution for on-site detection of ethylenediamine, overcoming the limitations of traditional detection methods that hinder real-time on-site detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Figure 1 is a diagram showing the coordination structure of the zinc-based porous coordination polymer of the present invention (for clarity, hydrogen atoms are not shown); Figure 2 3D structure diagram of the pores of the zinc-based porous coordination polymer of the present invention (for clarity, hydrogen atoms are not shown); Figure 3 The experimental and simulated powder X-ray diffraction patterns of the zinc-based porous coordination polymer of the present invention; Figure 4 The powder X-ray diffraction patterns of the zinc-based porous coordination polymer of the present invention immersed in different organic solvents; Figure 5 is a thermogravimetric analysis curve of the zinc-based porous coordination polymer of the present invention; Figure 6The excitation and emission spectra of the zinc-based porous coordination polymer (3 mg) of the present invention dispersed in DMF (5 mL) solvent; Figure 7 The fluorescence emission spectra of the zinc-based porous coordination polymer (3 mg) of the present invention dispersed in DMF (5 mL) and 130 μL of various organic solvents (10 mM) were added (excitation wavelength: 374 nm). Figure 8 The figure shows the fluorescence emission intensity comparison of the zinc-based porous coordination polymer (3 mg) of the present invention dispersed in DMF (5 mL) and after adding 130 μL of various organic solvents (10 mM) (excitation wavelength is 374 nm). Figure 9 The following are photos of the zinc-based porous coordination polymer (3 mg) of the present invention dispersed in DMF (5 mL) and then added with 130 μL of various organic solvents (10 mM) under UV light. Figure 10 The zinc-based porous coordination polymer (3 mg) of the present invention was dispersed in DMF (5 mL). Different concentrations of ethylenediamine (8×10 -3 M) Fluorescence emission spectrum in DMF solution (excitation wavelength is 374 nm); Figure 11 The fluorescence intensity ratio I0 / I versus ethylenediamine concentration curve and Stern-Volmer curve of the zinc-based porous coordination polymer of the present invention are shown; Figure 12 is the time response curve of the zinc-based porous coordination polymer of the present invention to ethylenediamine; Figure 13 a is the sensor image capture and RGB value extraction of the zinc-based porous coordination polymer of the present invention based on a smartphone under ultraviolet light; b is the linear relationship between the grayscale value and the ethylenediamine concentration. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0025] The processes, conditions, reagents, experimental methods, etc. for carrying out the present invention, except for the contents specifically mentioned below, are all common knowledge and common general knowledge in the field and are not particularly limited by the present invention. The experimental methods without specific conditions in the examples are generally based on conventional conditions or conditions recommended by the manufacturer.

[0026] Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those generally understood by those skilled in the art to which this invention belongs. However, in the event of any conflict, the present specification, including the definitions, shall prevail.

[0027] In this invention, the organic ligand 5-(2-(pyridin-4-yl)vinyl)quinoline (PVQ) was synthesized according to the literature [Inorg. Chem. 2018, 57, 8627-8633]. All chemical reagents used in the experiment were commercially available analytical grade products without further purification. The specific raw materials were obtained as follows: zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) was purchased from Chengdu Kelong Chemical Co., Ltd. with analytical purity; 2,6-naphthalenedicarboxylic acid (H₂NDC) was purchased from Shanghai Titan Technology Co., Ltd. with a purity of ≥98%. -Dimethylformamide (DMF) was purchased from Zhejiang Hannuo Chemical Technology Co., Ltd. with a purity of ≥99.5%.

[0028] Example 1 Preparation, structure identification, and performance testing of zinc-based porous coordination polymer materials (1) Preparation of zinc-based porous coordination polymer materials 12 mg (0.05 mmol) of 5-(2-(pyridin-4-yl)vinyl)quinoline organic ligand, 22 mg (0.1 mmol) of 2,6-naphthalenedicarboxylic acid and 30 mg (0.1 mmol) of Zn(NO3)2·6H2O were dissolved in 3 ml -dimethylformamide (DMF) solvent, fully mixed and sealed, reacted at 105°C for 16 hours, and then cooled to room temperature. The final light yellow transparent square crystals were washed with DMF and naturally dried to obtain zinc-based porous coordination polymer material (Zn-MOF), with a crystal yield of 51.4% (based on Zn).

[0029] (2) Determination of the structure of zinc-based porous coordination polymers The single crystal of the polymer prepared in (1) was taken out from the mother liquor, and the crystal was sealed in a 0.2 mm boron glass tube under a microscope so that it was just stuck. The mother liquor was injected above and below the crystal, and AB mixed glue was sealed above and below the mother liquor so that the frame coordination polymer could remain stable for a long time at room temperature. Crystal data were collected at room temperature using a Rigaku R-AXISPIDER X-ray diffractometer (MoKα,λ= 0.71073 Å) produced in Japan. After collecting the data, the reduction operation was performed using RAPID Offline software, and the absorption correction (multi-scan method) was performed on SADABS. The space group was determined using RAPID Offline software, and the structure was solved using SHELXT software. The F was analyzed using the SHELXTL program.2 Refinement (nonlinear least squares technique) was performed. Platon software could not directly resolve the framework structure without the guest molecule, so the Platon software's Squeeze program was used to obtain the framework structure without the guest molecule. Some parameters for crystallographic diffraction point data collection and structure refinement are shown in Table 1 below.

[0030] Table 1 Parameters of zinc-based porous coordination polymer crystals

[0031] Figure 1 、 2 is a schematic diagram of the coordination structure of the zinc-based porous coordination polymer, wherein Figure 1 The coordination mode of the metal zinc ion is shown in Figure 2 This is the three-dimensional structure diagram of the zinc-based porous coordination polymer.

[0032] (3) Powder diffraction characterization of phase purity Powder diffraction measurements were performed using a MiniFlex 600 automated X-ray diffractometer using Cu Kα radiation (graphite monochromator, 40 kV, 15 mA), a scan range of 3–50° (2θ), and a scan rate of 5° / min. Powder diffraction patterns were simulated using Mercury 1.4.2 software.

[0033] Figure 3 The experimental and simulated powder X-ray diffraction patterns of the zinc-based porous coordination polymer Zn-MOF are shown in Figure 1. The experimental diffraction pattern of the prepared Zn-MOF is highly consistent with the theoretical pattern based on single crystal structure simulation, confirming the high phase purity of the material.

[0034] The powder X-ray diffraction patterns of the zinc-based porous coordination polymer after being immersed in different organic solvents are shown in FIG. Figure 4 The analysis found that the diffraction peak positions of all samples were highly consistent with those of the original samples. This result shows that after being treated with different organic solvents, the zinc-based porous coordination polymer can still maintain its original crystal framework structure.

[0035] (4) Thermal stability of zinc-based porous coordination polymers The thermal stability of the Zn-based porous coordination polymer was tested by thermogravimetric analysis. The samples were analyzed using a TA Instrument SDT-650 thermogravimetric analyzer under the following conditions: a nitrogen atmosphere, a temperature range of 25–650°C, and a heating rate of 10°C / min.

[0036] See the results Figure 5Thermogravimetric analysis results show that the prepared zinc-based porous coordination polymer has excellent thermal stability, and its skeleton structure remains stable below 370°C. Thermogravimetric curve analysis and calculations show that each structural unit contains 4.5 DMF molecules and 0.5 water molecules.

[0037] (IV) Fluorescence properties of zinc-based porous coordination polymers Fluorescence spectroscopy experiments were performed using a Hitachi FL-4600 fluorescence spectrophotometer. The fluorescence of zinc-based porous coordination polymer (Zn-MOF) in DMF solution. After excitation at 374 nm, the compound exhibited a maximum emission peak at 436 nm ( Figure 6 ).

[0038] Example 2 Preparation of zinc-based porous coordination polymer This embodiment differs from Example 1 in that the molar ratio of 2,6-naphthalene dicarboxylic acid, zinc nitrate hexahydrate, and 5-(2-(pyridin-4-yl)vinyl)quinoline is 1:1:1, the reaction temperature is 120° C., and the reaction time is 12 hours. The rest is the same as Example 1.

[0039] The structural characteristics of the zinc-based porous coordination polymer prepared in this example are the same as those described in Example 1, belonging to the triclinic system, P-1 space group, with the same unit cell parameters and structural characteristics, and the crystal yield is 58.4% (based on Zn).

[0040] Example 3 Preparation of zinc-based porous coordination polymer This embodiment differs from Example 1 in that the molar ratio of 2,6-naphthalene dicarboxylic acid, zinc nitrate hexahydrate, and 5-(2-(pyridin-4-yl)vinyl)quinoline is 1:1:0.8, the reaction temperature is 90° C., and the reaction time is 24 hours. The rest is the same as Example 1.

[0041] The structural characteristics of the zinc-based porous coordination polymer prepared in this example are the same as those described in Example 1, belonging to the triclinic system, P-1 space group, with the same unit cell parameters and structural characteristics, and the crystal yield is 40.7% (based on Zn).

[0042] Example 4 Application of a zinc-based porous coordination polymer in fluorescence sensing of ethylenediamine 3 mg of the zinc-based porous coordination polymer (prepared in Example 1) was dispersed in 5 mL of DMF solution and sonicated for 30 minutes to prepare a uniform suspension. Then, 130 μL of DMF solution of organic solvents (including methanol, ethanol, ether, acetonitrile, acetone, chloroform, DMA, triethylamine, diethylamine, and ethylenediamine) was added to the 3 mL suspension. The luminescence spectra after adding various organic solvents were measured using a fluorescence spectrometer at an excitation wavelength of 374 nm and compared with the peak intensity of the maximum emission.

[0043] See the results Figure 7 and Figure 8 The results showed that after adding other organic solvents, the luminescence intensity of the compound remained basically unchanged, while after adding ethylenediamine solution, the fluorescence intensity of the zinc-based porous coordination polymer (Zn-MOF) showed a significant quenching phenomenon. At the same time, direct observation under ultraviolet light further confirmed this specific response ( Figure 9 ), which shows that Zn-MOF has selective recognition ability for ethylenediamine.

[0044] In order to better understand the recognition process of ethylenediamine by Zn-MOF, a fluorescence titration experiment was conducted. Ethylenediamine solution (8×10 -3 M), the fluorescence spectrum of the process was measured and recorded. Figure 10 As shown in Figure 3, the luminescence intensity of Zn-MOF gradually decreases with the increase of ethylenediamine concentration. When the concentration of ethylenediamine reaches 426.67 μM, the fluorescence of Zn-MOF is basically completely quenched.

[0045] The fluorescence quenching efficiency was further analyzed using the Stern–Volmer (SV) equation: I0 / I = 1+Ksv [A], where I0 is the initial fluorescence intensity before adding the analyte, I is the fluorescence intensity in the presence of the analyte, [A] is the molar concentration of the analyte, and Ksv is the quenching constant. When the EDTA concentration was lower than 53.33 μM, the curve was linear, and the calculated Ksv = 7.6×10 3 M -1 ( Figure 11 The detection limit (LOD) of ethylenediamine was calculated using the following formula: LOD = 3σ / slope, where σ is the standard deviation of the luminescence intensity of the blank solution. The detection limit of ethylenediamine for the Zn-MOF prepared in this invention reached 5.78 μM, which is significantly lower than that of the coordination polymer sensor {[Cd(L)(glu)]·3H2O} reported in the literature. ∞ The detection limit of Zn-MOF was 19.9 μM [Chem. Asian J. 2019, 14, 4420-4428.]. These results indicate that Zn-MOF shows promise as a selective fluorescent probe for ethylenediamine detection.

[0046] Figure 12 This is the time response curve of Zn-MOF to ethylenediamine. It can be seen that the Zn-MOF can quickly respond and recognize ethylenediamine in less than 15 seconds, indicating that Zn-MOF has high sensitivity to ethylenediamine and has the characteristics of rapid sensing.

[0047] Example 5 A portable ethylenediamine fluorescence sensing system To facilitate real-time monitoring, a portable ethylenediamine fluorescence sensing system integrating a UV lamp and a smartphone was constructed. This system consists of three main components: the sensing material (the porous polymer prepared in Example 1), a smartphone RGB analysis platform, and a visualization detection module based on fluorescence quenching response.

[0048] The smartphone RGB analysis platform consists of the following components: (1) Light source module: A UV LED light source with a wavelength of 365 nm and a power of 3 W is used to excite the fluorescence of the zinc-based porous coordination polymer; (2) Sample cell: Made of transparent quartz, with an inner diameter of 10 mm, capable of accommodating 0.5-5 mL of sample solution; (3) Mobile phone fixing bracket: The bracket adopts an adjustable angle design to ensure that the mobile phone camera maintains a fixed distance (about 10 cm) and angle (90°) with the sample pool; (4) Smartphone application: Using professional-grade image acquisition and RGB data analysis software (Color Recognition, developed by Kaifeng Lefan Network Technology Co., Ltd.), the fluorescence signal can be captured in real time and converted into RGB values.

[0049] The visualization detection module based on fluorescence quenching response includes: (1) Signal acquisition unit: The fluorescence images of the Zn-based porous coordination polymer at different EDTA concentrations are captured by a smartphone camera; (2) RGB analysis unit: converts the captured fluorescence image into RGB values ​​and calculates the relative fluorescence intensity change; (3) Data processing unit: establish a standard curve between fluorescence intensity and ethylenediamine concentration, and automatically calculate the ethylenediamine concentration in unknown samples through an algorithm; (4) Visual display unit: Displays the test results in the form of intuitive charts, including concentration values, change trends and warning information.

[0050] The working principle of this sensing system is based on the host-guest interaction between zinc-based porous coordination polymer and ethylenediamine. When ethylenediamine molecules enter the pores of zinc-based porous coordination polymer, they interact with the PVQ ligands and 2,6-NDC in the framework. 2-The ligand undergoes host-guest interaction, leading to fluorescence quenching. This fluorescence change is captured by the smartphone RGB analysis platform, and the visual detection module converts the signal into readable data, enabling rapid and accurate detection of ethylenediamine.

[0051] The experiment found that as the concentration of ethylenediamine increased, the fluorescence intensity of the material under ultraviolet light showed a regular decrease. The fluorescence images were taken with a smartphone and analyzed in RGB mode using professional color analysis software "Color Recognition", which improved the accuracy and reliability of visual inspection ( Figure 13 a). Furthermore, a quantitative relationship between gray value (calculation formula: 0.299R+ 0.587G + 0.114B) and ED concentration was established ( Figure 13 b) The linear equation is Y = 98.14 - 0.75 [ethylenediamine], with a good correlation coefficient and a detection limit of 9.97 μM. This portable smartphone-UV detection platform offers advantages such as ease of operation and rapid response, providing an efficient and reliable solution for on-site detection of ethylenediamine.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A zinc-based porous coordination polymer for fluorescence detection of ethylenediamine, the chemical formula of which is [Zn2(2,6-ndc)2(pvq)]·4.5DMF·0.5H2O, where 2,6-ndc 2- The anion of 2,6-naphthalene dicarboxylate is PVQ, the organic ligand is 5-(2-(pyridin-4-yl)vinyl)quinoline. The polymer material belongs to the triclinic system, the space group P-1, the unit cell parameters are a = 13.058(3) Å, b = 13.079(3) Å, c = 17.093(3) Å, α = 103.75(3)º, β = 96.51(3)º, γ = 92.31(3)º, and the unit cell volume V = 2810.4(10) Å. 3 .

2. The zinc-based porous coordination polymer according to claim 1, characterized in that: The polymer structure contains a binuclear [Zn2(COO)4] paddle-wheel secondary building block, which is connected to the 2,6-ndc 2- The ligands are bridged to form a square lattice network, and the PVQ ligands are used to support a three-dimensional framework with PCU topology. Two identical three-dimensional frameworks interpenetrate each other to form a double interpenetrating structure, forming a three-dimensional channel. The porosity calculated by Platon is 50.2%.

3. A method for preparing the zinc-based porous coordination polymer according to any one of claims 1 to 2, comprising the following steps: (1) Add 2,6-naphthalene dicarboxylic acid, 5-(2-(pyridin-4-yl)vinyl)quinoline and zinc nitrate hexahydrate to -Mix evenly in dimethylformamide solvent; (2) The mixture obtained above was sealed and subjected to a solvothermal reaction at 90-120°C for 12-24 hours, and then naturally cooled to room temperature to obtain light yellow transparent square crystals; (3) Use The square crystals are washed with dimethylformamide and dried naturally to obtain the zinc-based porous coordination polymer.

4. The method for preparing the zinc-based porous coordination polymer according to claim 3, wherein: The molar ratio of 2,6-naphthalenedicarboxylic acid, zinc nitrate hexahydrate and 5-(2-(pyridin-4-yl)vinyl)quinoline in step (1) is 1:1:0.5 to 1:1:

1.

5. The method for preparing the zinc-based porous coordination polymer according to claim 3, wherein: The molar volume ratio of 2,6-naphthalenedicarboxylic acid to the solvent in step (1) is 0.1:3, and the unit is mmol / mL.

6. Use of the zinc-based porous coordination polymer according to any one of claims 1 to 2 in fluorescence sensing of ethylenediamine.

7. The use according to claim 6, characterized in that: The detection method is as follows: the polymer is dispersed in -dimethylformamide to form a suspension, add the analyte to the suspension, and identify ethylenediamine through the fluorescence quenching effect.

8. A portable ethylenediamine fluorescence sensing system, characterized in that Include: (i) The zinc-based porous coordination polymer according to claims 1-2 is used as a sensing material; (ii) Smartphone RGB analysis platform; (iii) A visualization detection module based on fluorescence quenching response enables specific detection of ethylenediamine.

9. The sensing system according to claim 8, characterized in that: The response time is less than 15 seconds and the detection limit is at the micromolar level.

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