Application of europium-based metal-organic framework material in detection of trace energetic materials

Abstract

The application discloses application of a europium-based metal organic framework material in detection of trace energetic materials. The europium-based metal organic framework material Eu-MOF is synthesized by using europium salt and high conjugated organic ligand as raw materials through a hydrothermal method, and has obvious fluorescence characteristics. Under the same excitation wavelength, the high-efficiency sensing of trace energetic materials in an organic solvent is realized by the change of the fluorescence spectrum curve after adding energetic materials with different ppb concentration levels, and quantitative analysis is realized by the intensity change of the characteristic peak. The europium-based metal organic framework material synthesized by the application has the advantages of simple preparation, good stability, quick and simple detection method of trace energetic materials, no need of complex pretreatment, good selectivity, high sensitivity and the like, is sensitive to tetrazole energetic materials in particular, and is also effective for nitro aryl energetic materials.

Description

Technical Field

[0001] This invention relates to the application of europium-based metal-organic framework materials in the detection of trace energetic materials, belonging to the field of fluorescent detection technology for energetic materials. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of porous materials formed by the self-assembly of metal ions or metal clusters with organic ligands. They possess large specific surface areas, controllable pore structures, easily modifiable surfaces, and tunable chemical functions, leading to a wide range of applications, including gas separation and adsorption, drug delivery, and fluorescence sensing. In recent years, MOF-based fluorescence sensing technology has become a research hotspot in this field due to its significant advantages, such as fast response speed, excellent portability, and high visualization, which outperform traditional sensing methods. Lanthanide-based metal-organic frameworks (Ln-MOFs) are materials formed by the bonding of secondary structural units of lanthanide metal ions with organic ligands. Benefiting from the special ligand-metal energy transfer, lanthanide ions exhibit unique luminescence properties such as narrow emission peaks and long-lived excited states in their 4f-4f electronic transitions. They also possess large Stokes shifts, high quantum yields, and high luminescence efficiency. These properties make them excellent material candidates for the field of sensing, especially in the sensing of nitro-aromatic explosives.

[0003] Currently, most research on Ln-MOFs sensing focuses on nitro-based energetic materials, with limited research on non-nitro-based materials. Furthermore, most studies concentrate on ppm-level detection, exhibiting weak detection capabilities at ppb or ppt levels. Therefore, developing a fluorescent probe with trace detection capabilities for Ln-MOFs in the detection of energetic materials holds great promise for achieving trace detection and sensitive identification of energetic materials. Summary of the Invention

[0004] Based on the existing problems of using Ln-MOFs as fluorescent probes for the detection of energetic materials, the purpose of this invention is to provide a lanthanide metal-organic framework fluorescent probe for the detection of trace amounts of energetic materials. By combining the emission characteristics of lanthanide metals with fluorescence analysis technology, energetic materials can be detected at the ppb level.

[0005] To achieve the above objectives, this invention provides an application of europium-based metal-organic framework materials in the detection of trace energetic materials.

[0006] Furthermore, the chemical formula of this europium-based metal-organic framework material is [Eu2(Cu8I8)(C 12[H8NO2)6(H2O)4]·5C4H8O2, whose organic ligand is 3-pyridin-4-ylbenzoic acid (Hpba), is formed by six Hpba ligands connected by Cu8I8 clusters to form nodes, Eu 3+ Ions are bridged by carboxylic acid groups to form one-dimensional (1D) chains, which together construct a three-dimensional framework containing two different sizes of 1D channels, which can be occupied by guest molecules of different sizes.

[0007] Furthermore, the europium-based metal-organic framework material is prepared through the following steps:

[0008] S1. Weigh europium nitrate hexahydrate, 3-(pyridin-4-yl)benzoic acid, potassium iodide, and cuprous iodide. Dissolve the four in a mixed solvent and stir for 3-5 hours. Transfer the mixture to a reaction vessel.

[0009] S2. Place the reactor in a constant temperature oven and react at 100-120℃ for 3-5 days. After post-processing, Eu-MOFS is obtained. S3. After the reaction is complete, take out the product from the reactor, separate the solid and liquid, and centrifuge and wash.

[0010] S4. Dry in a vacuum drying oven at 100-120℃ for 6-8 hours to obtain the europium-based metal-organic framework material.

[0011] Specifically, in S1, the molar ratio of europium nitrate hexahydrate, 3-(pyridin-4-yl)benzoic acid, potassium iodide, and cuprous iodide is 1:2:1.5:1.

[0012] Specifically, in S1, the mixed solvent is 1,4-dioxane and deionized water in a volume ratio of 3:2.

[0013] Specifically, the concentrations of each raw material in the mixed solvent are: europium nitrate hexahydrate 0.02M, 3-(pyridin-4-yl)benzoic acid 0.03M, cuprous iodide 0.02M, and potassium iodide 0.04M.

[0014] Furthermore, the application includes the following steps:

[0015] S1. Dissolve the europium-based metal-organic framework material in a solvent and ultrasonically disperse it for 30 minutes to prepare a stable suspension;

[0016] S2. Take the energetic material solution and dilute it with a solvent to make standard solutions of different concentrations;

[0017] S3. Take the suspension from S1 into a 5mL centrifuge tube, add an equal volume of standard solution, and mix.

[0018] S4. Transfer the mixture from S3 to a cuvette and place it in a fluorescence spectrometer to scan the fluorescence spectrum and obtain the fluorescence spectrum.

[0019] S5. Using fluorescence spectra, a standard curve is plotted between fluorescence intensity and the concentration of energetic materials. The standard curve is then used to detect energetic materials at the desired concentration.

[0020] Specifically, energetic materials include nitro aromatics, nitrate esters, nitramines, nitrates, perchlorates, and high-nitrogen and all-nitrogen energetic materials.

[0021] More specifically, the energetic material may be a di-based drug, ammonium nitrate, ammonium perchlorate, 2,4-dinitroanisole, nitroguanidine, cyclotetramethylenetetranitramine, pentaerythritol tetranitrate, cyclotrimethylenetrinitramine, 2,4,6-trinitrotoluene, or 1,1′-dihydroxy-5,5′-bitetrazolium dihydroxyamine salt.

[0022] Specifically, the fluorescence excitation wavelength for the fluorescence analysis is 350 nm, and the scanning range is 380-680 nm.

[0023] Specifically, the Eu 3+ The wavelength at the peak of the emitted light is 620nm.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. Ln-MOF is prepared by hydrothermal synthesis, which is simple.

[0026] 2. The obtained Eu-MOF fluorescent probe exhibits good fluorescence properties in DMF.

[0027] 3. The prepared Eu-MOF molecules have good fluorescence response to trace energetic materials and are capable of detecting non-nitro energetic materials that are rarely seen in current research, such as TKX-50.

[0028] 4. Simple detection, capable of testing trace levels. The energetic material solution is directly added to the probe solution, and the change in fluorescence spectrum is used to sense trace amounts of the energetic material. Attached Figure Description

[0029] Figure 1 This is the XRD spectrum of the europium-based metal-organic framework fluorescent probe (Eu-MOF) synthesized in this invention for detecting energetic materials.

[0030] Figure 2 The images show (a) ppb-level fluorescence emission spectra and (b) ppb-level relative emission intensity trends of Eu-MOF after adding different concentrations of TKX-50 (based on the emission intensity in DMF).

[0031] Figure 3The images show (a) ppb-level fluorescence emission spectra and (b) ppb-level relative emission intensity trends of Eu-MOF after adding different concentrations of NQ (based on the emission intensity in DMF).

[0032] Figure 4 The images show (a) ppb-level fluorescence emission spectra and (b) ppb-level relative emission intensity trends of Eu-MOF after the addition of different concentrations of DNAN (based on the emission intensity in DMF). Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments and accompanying drawings. These embodiments are only described as preferred embodiments of the present invention and are not limited to the scope of the present invention.

[0034] Example 1

[0035] Synthesis of lanthanide metal-organic framework materials: 0.045 g europium nitrate hexahydrate, 0.030 g 3-(pyridin-4-yl)benzoic acid, 0.019 g cuprous iodide, and 0.032 g potassium iodide were weighed and placed in the liner of a 25 mL reaction vessel. 2.0 mL of deionized water and 3.0 mL of 1,4-dioxane were added, and the mixture was stirred at room temperature for 3 h to dissolve, yielding an orange-yellow solution. The vessel was sealed and the reaction vessel was transferred to a 100 °C constant temperature oven for 3 days. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. The product was filtered and washed three times with DMF and 1,4-dioxane to obtain a yellow solid sample. The solid sample was vacuum dried at 100 °C for 6 h to obtain the europium-based metal-organic framework material described in this invention.

[0036] Figure 1 This is the PXRD spectrum of the Eu-MOF obtained in Example 1. (From...) Figure 1 The XRD diffraction curves showed diffraction peaks at positions 4, 6, 8, and 9, confirming the successful synthesis of europium-based metal-organic frameworks (Eu-MOFs). The prepared europium-based metal-organic frameworks were then used to detect energetic materials.

[0037] Weigh 2 mg of finely ground Eu-MOF and disperse it in 1.5 mL of DMF, then sonicate for 30 min. Prepare equal volumes of TKX-50 / DMF solutions of different concentrations and add them to the solution to form stable suspensions. Simultaneously, prepare a suspension with an equal volume of DMF as a blank control. After shaking, set the excitation wavelength to 350 nm and perform fluorescence spectroscopy. Compare the fluorescence intensity of Eu-MOF with different concentrations of TKX-50 with that of Eu-MOF with only pure solvent. The measured fluorescence results are as follows: Figure 2 As shown. By Figure 2From (a), we can see that Eu-MOF exists at 592nm, 613nm, and 620nm, respectively. 5 D0→ 7 F1 5 D0→ 7 F2 Eu 3+ The characteristic emission peak is located at 620 nm, with the strongest emission peak at that point. Figure 2 As shown in (b), Eu-MOF exhibits a slight enhancement trend when ppb-level TKX-50 is added, and this enhancement generally increases with increasing concentration. This demonstrates a trend not seen in other MOFs. Overall, there is ppb-level fluorescence enhancement for TKX-50.

[0038] Example 2

[0039] This embodiment is the same as Embodiment 1, except that the energetic material to be tested is NQ, and the fluorescence test results are as follows. Figure 3 As shown. By Figure 3 It can be seen that when ppb-level NQ is added, the change trend of Eu-MOF is not significant, and it does not show enhancement; on the contrary, the fluorescence intensity decreases. Figure 2 Compared to TKX-50 detected in Example 2, the change in NQ was weaker, and the detection effect was not as strong as that of TKX-50.

[0040] Example 3

[0041] This embodiment is the same as Example 1, except that the energetic material to be tested is DNAN, and the fluorescence test results are as follows. Figure 4 As shown. By Figure 4 It can be seen that, overall, when ppb-level DNAN is added, Eu-MOF exhibits a slight enhancement trend. Furthermore, the relative fluorescence intensity generally increases with increasing DNAN concentration. Overall, a ppb-level fluorescence enhancement phenomenon also exists for DNAN. (Comparison) Figure 2 and Figure 3 Compared to TKX-50 detected in Example 2, the fluorescence change effect was weaker. Compared to NQ detected in Example 3, DNAN achieved a more significant fluorescence change effect, with an enhancement of 20%.

Claims

1. Application of a europium-based metal-organic framework material in the detection of trace energetic materials.

2. The application as described in claim 1, characterized in that, The chemical formula of this europium-based metal-organic framework material is [Eu2(Cu8I8)(C 12 [H8NO2)6(H2O)4]·5C4H8O2, whose organic ligand is 3-pyridin-4-ylbenzoic acid Hpba, is formed by six Hpba ligands connected by Cu8I8 clusters to form nodes, Eu 3+ Ions are bridged by carboxylic acid groups to form one-dimensional chains, which together construct a three-dimensional framework containing two different sizes of one-dimensional channels, which can be occupied by guest molecules of different sizes.

3. The application as described in claim 1 or 2, characterized in that, The europium-based metal-organic framework material is prepared through the following steps: S1. Weigh europium nitrate hexahydrate, 3-(pyridin-4-yl)benzoic acid, potassium iodide, and cuprous iodide. Dissolve the four in a mixed solvent and stir for 3-5 hours. Transfer the mixture to a reaction vessel. S2. Place the reactor in a constant temperature oven and react at 100-120℃ for 3-5 days. After post-processing, Eu-MOFS is obtained. S3. After the reaction is complete, take out the product from the reactor, separate the solid and liquid, and centrifuge and wash. S4. Dry in a vacuum drying oven at 100-120℃ for 6-8 hours to obtain the europium-based metal-organic framework material.

4. The application as described in claim 3, characterized in that, In S1, the molar ratio of europium nitrate hexahydrate, 3-(pyridin-4-yl)benzoic acid, potassium iodide, and cuprous iodide is 1:2:1.5:

1.

5. The application as described in claim 3, characterized in that, In S1, the mixed solvent is 1,4-dioxane and deionized water in a volume ratio of 3:

2.

6. The application as described in claim 3, characterized in that, The concentrations of each raw material in the mixed solvent are: europium nitrate hexahydrate 0.02M, 3-(pyridin-4-yl)benzoic acid 0.03M, cuprous iodide 0.02M, and potassium iodide 0.04M.

7. The application as described in claim 1, characterized in that, The application has the following steps: S1. Dissolve the europium-based metal-organic framework material in a solvent and ultrasonically disperse it for 30 minutes to prepare a stable suspension; S2. Take the energetic material solution and dilute it with a solvent to make standard solutions of different concentrations; S3. Take the suspension from S1 into a 5mL centrifuge tube, add an equal volume of standard solution, and mix. S4. Transfer the mixture from S3 to a cuvette and place it in a fluorescence spectrometer to scan the fluorescence spectrum and obtain the fluorescence spectrum. S5. Using fluorescence spectra, a standard curve is plotted between fluorescence intensity and the concentration of energetic materials. The standard curve is then used to detect energetic materials at the desired concentration.

8. The application as described in claim 7, characterized in that, Energetic materials include nitro aromatics, nitrate esters, nitramines, nitrates, perchlorates, high-nitrogen and all-nitrogen energetic materials.

9. The application as described in claim 8, characterized in that, The energetic material is any one of the following: a dual-base drug, ammonium nitrate, ammonium perchlorate, 2,4-dinitroanisole, nitroguanidine, cyclotetramethylenetetranitramine, pentaerythritol tetranitrate, cyclotrimethylenetrinitramine, 2,4,6-trinitrotoluene, and 1,1′-dihydroxy-5,5′-bitetrazolium dihydroxyamine salt.

10. The application as described in claim 7, characterized in that, The fluorescence excitation wavelength for the fluorescence analysis is 350 nm, and the scanning range is 380-680 nm.

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