MOF (Metal Organic Framework) material, preparation method thereof, acid-loaded inorganic salt sol and peroxide explosive detection application

Abstract

The embodiment of the invention relates to an MOF (Metal Organic Framework) material, a preparation method thereof, acid-loaded inorganic salt sol and peroxide explosive detection application, and belongs to the technical field of fluorescence detection materials. The preparation method of the acid-loaded inorganic salt sol capable of cyclically detecting the peroxide explosive comprises the following steps: putting an MOF material and a film dispersion polymer into a solvent, so that the film dispersion polymer wraps the MOF material, and uniformly mixing to obtain gel; and adding acid into the gel, and reacting to load the acid on the gel to obtain the acid-loaded inorganic salt sol. The acid-loaded inorganic salt sol in the embodiment of the invention shows extremely high sensitivity, and the lowest detection limit can reach 10 nanograms (taking TATP as an example); in addition, the material shows excellent performance of resisting photooxidation quenching (namely resisting photobleaching) in a test environment, and can be quickly self-healed; even if the material is continuously tested for more than 500 times, the material can still keep activity and can be recycled without being damaged.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of fluorescent detection materials, and in particular to a MOF material and a preparation method thereof, an acid-loaded inorganic salt sol, and an application in the detection of peroxide explosives. Background Art

[0002] Energetic compounds (such as explosives, propellants, and fireworks) can trigger violent chemical reactions in military and civilian fields, releasing large amounts of heat, pressure, and gas. With the continuous development and increase in the variety of high-energy-density materials, how to effectively identify these materials has become a very challenging task. Therefore, it is particularly important to develop a variety of sensors that can detect these dangerous goods.

[0003] In traditional high-energy explosives, such as nitroaromatics, nitrate esters, nitramines, and nitroalkanes, the molecules usually contain one or more nitro groups. These nitro groups are prone to complexation reactions with electron-rich substances due to their lack of electrons, and are then detected through dipole-dipole interactions. However, peroxide-type dangerous substances (such as TATP, DADP, HMTD, etc.) are explosives that are easy to synthesize, easy to decompose, and highly explosive. Because they are mostly white and odorless and do not contain nitro groups, they are difficult to detect through broad-spectrum chemical reactions like nitro explosives. The explosion principle of peroxide explosives is to quickly release a large amount of gas in a limited space, resulting in a sharp increase in pressure and triggering an explosion, which makes it difficult to effectively detect them by conventional methods. Therefore, peroxide explosives are special among many explosives, and their identification is more difficult. Common peroxide explosives are as follows:

[0004]

[0005] In view of these aspects, the development of materials that can widely test peroxide explosives appears to have great advantages, and can detect various explosive mixtures based on peroxides, such as TATP / AN, Oil / AN, TATP / UrN, TATP / W and TATP / AN / W (ammonium nitrate-AN, urea nitrate-UrN, water-W and Oil-oil) based on triperoxide acetone. Some common examples of vapor detection of peroxide explosives are: using the specific reaction of hydrogen peroxide and borate esters to design and synthesize borate ester probes containing fluorescent chromophores. However, this method has the following obvious defects: first, the number of times the borate ester probe can be recycled is extremely limited, and it usually becomes invalid and scrapped after only a few uses; second, the stability of the borate ester itself is poor and it is difficult to store for a long time. In addition, another type of detection method uses acetone produced by the decomposition of TATP to develop an acetone probe to detect TATP. However, this method also has limitations and cannot detect explosives that cannot be decomposed into acetone, such as HMTD. In addition, when acetone is present in the mixture, false positives will be generated, resulting in inaccurate test results and the interference cannot be eliminated. Therefore, although existing detection methods can identify peroxide explosives to a certain extent, they often have significant deficiencies and further breakthroughs in materials and technologies are urgently needed to achieve more extensive and stable explosives detection.

[0006] Compared with other detection methods, the new MOF material has unique advantages. It is not damaged by strong high temperature, strong ultraviolet and strong heat conditions. It has good thermal stability and chemical stability. Its sensitivity is close to that of professionally trained detection dogs. It is low-cost, easy to make and easy to operate. These materials can not only detect the vapor of explosives, but also lay the foundation for the development of various on-site detection instruments. These instruments can be widely used in the security systems of high-speed rail stations, airports, bus stations, nuclear power plants and large conference sites, thereby effectively improving the fluorescent sensing detection capabilities of explosive gases and providing strong protection for national security and public safety.

[0007] For example, MOF materials show great potential for different explosives. For example, Professor Li Jing of Rutgers University published a MOF material [Zn2(oba)2(bpy)]·DMA for testing aromatic explosives in New Microporous Metal-Organic Framework Demonstrating Unique Selectivity for Detection of High Explosives and Aromatic Compounds, J.Am.Chem.Soc.2011,133,4153-4155, and a MOF material [Zn2(oba)2(bpy)]·DMA for testing aromatic explosives in Selective, Sensitive, and Reversible Detection of Vapor-Phase High Explosives via Two-Dimensional Mapping:A New Strategy for MOF-Based Sensors, Cryst.Growth. Des. 2013, 13, 4204-4207, published a test material (Zn)2(ndc)2P·xG [ndc=2,6-naphthalenedicarboxylate;P=1,2-bis(4-pyridyl)ethane(bpe)or 1,2-bis(4-pyridyl)-ethylene(bpee);G=guest / solvent molecule], José M. Pedrosa et al. in A lanthanide MOF immobilized in PMMA transparent films as a selective fluorescence sensor for nitroaromatic explosives vapours, J. Mater. Chem. C. 2020, 8, 3626-3630, introduces a highly selective and sensitive luminescent sensor based on a simple hybrid of Tb(III)-based luminescent metal-organic framework and poly(methyl methacrylate) that can correctly detect nitroaromatic vapors in the sub-ppb range.In addition, since TATP and its analogs can be decomposed into acetone under heating conditions, Zhang Ensheng et al. synthesized a novel high-sensitive Cd-MOF fluorescent probe [(CH3)2NH2]2Cd3(ptptc)2 for detecting acetone vapor in air and picric acid in water:Synthesis,structure and sensingproperties,Spectrochim.ActaA Mol.Biomol.Spectrosc.2021,246,118962, which is used to detect acetone vapor. It shows a highly sensitive fluorescence quenching response to trace acetone vapor. In the acetone concentration range of 0 to 430 ppm, there is a good linear relationship between the fluorescence change and the acetone vapor concentration. The detection limit of acetone is 86 ppm, showing good reusability and suitable for practical applications. Professor Yan Bing used A novel fluorescence probe for sensing organic amine vaporsfrom Eu. 3+ β-diketonate functionalized bio-MOF-1 hybrid system, J. Name. 2013, 00, 1-3. A bio-MOF-1, Zn8(ad)4(BPDC)6O·2Me2NH2 (BPDC=biphenyl-4,4'-dicarboxylate, Ad=adeninate) is described, which can be used to test organic small molecule amine vapor, and HMTD thermal decomposition can produce small molecule amine. The above results provide a theoretical and practical basis for MOF fluorescent vapor detection of various explosives, but there are still some shortcomings, some of which have serious disadvantages, such as acetone and small molecule organic amine test instead of TATP and HMTD, which cannot eliminate the interference of acetone and small molecule amine itself, thus leading to misjudgment, or the test of the above energetic explosives cannot be repeated for multiple cycles, and can only be tested once. Therefore, it is of practical significance to develop a type of peroxide explosive fluorescent probe with specificity, fast response, recoverability, high sensitivity, wide detection range and strong anti-interference ability. Summary of the invention

[0008] In view of this, the embodiments of the present application provide a MOF material and a preparation method thereof, an acid-loaded inorganic salt sol, and a peroxide explosive detection application, which can effectively overcome the defects existing in the above-mentioned prior art.

[0009] The first aspect of the embodiment of the present application provides a MOF material, wherein the MOF material is linked with metal ions or inorganic clusters as nodes and organic ligands as connectors, and the structure of the MOF material is composed of 2 ligands, 1 metal core center, and 4 / 2 halogen ligands. The structural formula of the MOF material is as follows:

[0010]

[0011] Wherein, Ligand_A and Ligand_B are both organic ligands; X is Cl or Br; M is selected from at least one of Pb, Zn, Cd, Mn, Sb, Ge, and Sn, and the M salt is a chloride metal salt or a bromide metal salt.

[0012] In some embodiments that may include the above embodiments, the Ligand_A is a neutral ligand, and its structural formula is as follows:

[0013]

[0014] Wherein, Ar is a substituted phenyl group or a phenyl group, and the substituent in the substituted phenyl group is selected from at least one of N(CH3)2, CF3, OCOCH3, NHCOCH3, and NCH3COCH3;

[0015] Wherein, Z represents -NN-, and N represents an aryl group or a condensed ring, the aryl group is selected from one of a para-disubstituted trifluoromethylphenyl, a dimethylaminophenyl, and a halogenated phenyl, and the condensed ring is selected from one of naphthalene, anthracene, phenanthrene, phenazine, and phenoxazine;

[0016] The Ligand_B is an ionic liquid containing N, S, and P, and its structural formula is as follows:

[0017]

[0018] Wherein, R1, R2, R3, R4 are each independently selected from alkyl C n H 2n+1 , alkenyl C n H 2n-1 , alkynyl C n H 2n-3 At least one of aryl, fluorenyl, n is 1-25 and is an integer; when it is alkenyl, n is 2-25 and is an integer.

[0019] The second aspect of the embodiment of the present application further provides a method for preparing the above-mentioned MOF material, comprising the following steps:

[0020] First, different ligands are synthesized, and then the different ligands are reacted with the metal core center through solvothermal reaction to obtain MOF materials.

[0021] The third aspect of the embodiment of the present application also provides a method for preparing an acid-loaded inorganic salt sol capable of cyclically detecting peroxide explosives, using the above-mentioned MOF material, comprising the following steps:

[0022] The MOF material and the membrane-dispersed polymer are dissolved in a solvent so that the membrane-dispersed polymer wraps the MOF material, and a gel is obtained after uniform mixing; an acid is added to the gel to react so that the acid is loaded on the gel to obtain an acid-loaded inorganic salt sol.

[0023] In some embodiments that may include the above embodiments, the acid is at least one of an inorganic acid, a heteropoly acid, and an organic acid; and the membrane dispersing polymer is at least one of PAM, PAN, and PEG.

[0024] In some embodiments that may include the above embodiments, nitride red phosphor is added to the acid-loaded inorganic salt sol to adjust its emission wavelength.

[0025] In some embodiments, which may include the above embodiments, the solvent is DMSO and / or DMF.

[0026] A fourth aspect of the embodiment of the present application further provides a vapor sensing membrane, wherein the acid-loaded inorganic salt sol prepared by the above-mentioned preparation method comprises the following steps:

[0027] The acid-loaded inorganic salt sol is prepared into a vapor sensing membrane by drop casting or spin coating.

[0028] A fifth aspect of the embodiments of the present application also provides application of the above-mentioned vapor sensing membrane in the detection of peroxide explosives.

[0029] In some embodiments that may include the above embodiments, the peroxide explosive is selected from at least one of triacetone triperoxide, diacetone diperoxide, hexamethylene triperoxide diamine, and tetramethylene diperoxide diurea.

[0030] This application uses the interaction between MOF materials and hydrogen peroxide and acetone for detection. Hydrogen peroxide has oxidizing properties because it contains multiple oxygen atoms and peroxide bonds, and can undergo oxidation reactions with MOF materials. There is also an interaction between heteroatoms (such as N, S, O, P) in MOF materials and hydrogen peroxide; and the effect of acetone within the framework of MOF materials will cause the solid-state fluorescence of MOF materials to change. This principle can be used to detect a variety of peroxide explosives, including triacetone triperoxide (TATP), diacetone diperoxide (DADP), hexamethylene triperoxide diamine (HMTD) and tetramethylene diperoxide diurea (TMDD).

[0031] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0032] During the detection process, the vapor sensing film prepared by the acid-loaded inorganic salt sol in the embodiment of the present application shows extremely high sensitivity, and the minimum detection limit can reach 10 nanograms (taking TATP as an example); in addition, the acid-loaded inorganic salt sol material shows excellent performance of resisting photooxidative quenching (i.e., resisting photobleaching) under the test environment, and can quickly self-heal; even if tested continuously for more than 500 times, the acid-loaded inorganic salt sol material can still maintain activity and can be recycled without damage; therefore, the vapor sensing film prepared by the acid-loaded inorganic salt sol material is very suitable for on-site alarm and steam sensing in harsh environments, with the advantages of fast response, recoverability, high sensitivity, wide detection range and strong anti-interference ability. In addition, considering the actual application needs, commercial nitride red phosphor can also be added to the acid-loaded inorganic salt sol material to adjust its color wavelength, thereby further expanding the application field of the acid-loaded inorganic salt sol material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 Schematic diagram of the acid-loaded inorganic salt sol, glass substrate luminescence and acrylic film luminescence of the embodiment of the present application;

[0035] Figure 2 The MOF_B material itself and its excited fluorescence luminescence image of the embodiment of the present application;

[0036] Figure 3 For SM1 1 H NMR: spectrum of CDCl3 distilled and dried;

[0037] Figure 4 TATP 1 HNMR: spectrum of CDCl31 / 1000 self-decomposition (1 / 1000 acetone);

[0038] Figure 5 For HMT 1 H NMR: CDCl3 spectrum;

[0039] Figure 6 HMTD 1 H NMR: CDCl3 spectrum to be prepared;

[0040] Figure 7In-situ UV absorption and excitation spectra of MOF_B material;

[0041] Figure 8 It is the UV excitation spectrum of acid-loaded inorganic salt sol;

[0042] Fig. 9 The fluorescence quenching images of the obtained film stained with TATP and unstained;

[0043] Fig.10 is the fluorescence spectrum of the film measured at different temperatures;

[0044] Fig.11 It is the TATP response test image;

[0045] Fig.12 Real-time response signal image of pure DADP;

[0046] Fig.13 It is the real-time response signal image of HMTD steam;

[0047] Fig.14 It is a real-time response signal image of TATP steam;

[0048] Fig.15 It is a real-time response signal image of trace TATP vapor;

[0049] Fig.16 Real-time response image of recoverable and highly sensitive TPAP vapor fluorescence quenching;

[0050] Fig.17 This is the real-time response signal image of di-tert-butyl hydroperoxide vapor. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] (1) The fluorescence detection sensing principle of the embodiment of the present application is:

[0053] 1. Since MOF materials are porous organic framework materials, the metal centers are Pb, Zn, Cd, Mn, Sb, Ge, and Sn ions, which can be excited to have strong fluorescence. The absorption wavelength is 360-370nm, and the excitation wavelength is about 480-800nm ​​(wavelength red shift). In addition, since they are porous organic frameworks, they can prevent them from stacking up with each other to form a hollow stacked structure, which helps to weaken their aggregation-induced fluorescence quenching (ACQ), thereby meeting the basic conditions for realizing fluorescence detection;

[0054] 2. Peroxide explosives, including triacetone triperoxide (TATP), diacetone diperoxide (DADP), hexamethylene triperoxide diamine (HMTD) and tetramethylene diurea peroxide (TMDD), all contain peroxide bonds and can be decomposed into hydrogen peroxide, acetone and small molecule organic amines under acidic conditions. The MOF material has a fluorescence quenching effect on all three of the above, and can respond cyclically, which is more advantageous than the single detection of hydrogen peroxide or acetone or small molecule organic amines. The decomposition of explosives into hydrogen peroxide, acetone and small molecule organic amines is shown below:

[0055]

[0056] 3. Since the MOF structure of MOF materials can form pillar channels, MOF_A or MOF_B materials are arranged to form a topological structure, which can further form a gas path to promote the entry of explosive molecules. The channel has a certain diameter or radius, and can only pass molecules of a certain volume, restricting other molecules that do not meet the requirements (large volume) from entering, thereby more specifically testing small molecule vapor. The schematic diagram of the topological arrangement of MOF is shown below:

[0057]

[0058] 4. Since the acid-loaded inorganic salt sol is relatively viscous, the spin-coated film can form a porous structure due to the action of the air and water phase, and then fully contact with the generated small molecules to produce a fluorescent reaction. The polymer is hydroperoxide- or amine- and acetone-philic, which can further increase the sensitivity and facilitate the preparation of the film, making it convenient for vapor sensing. The reaction of the formed topologically arranged ordered structure to peroxide explosives is shown below:

[0059]

[0060] Among them, the expanded molecular circle represents the membrane-dispersed polymer, the two horizontal lines below the molecule represent the superacid, and the entire structure indicates that the MOF material is wrapped by the membrane-dispersed polymer and loaded with superacid.

[0061] (2) Sources of raw materials and detection methods of the examples of this application:

[0062] 1. Most of the main raw material ligands are directly commercially available from reagent companies, and only a small amount is synthesized, as can be seen in the Examples section; the tested triacetone triperoxide (TATP), diacetone diperoxide (DADP) and hexamethylene triperoxide diamine (HMTD) etc., because they are easily decomposed and deteriorated at room temperature, they all need to be synthesized, and a small amount of synthesis is completed and used immediately, and the specific synthesis can be seen in the Examples section.

[0063] 2. In CDCl3 solution, the Varian liquid NMR instrument (400MHz) of West Lake University was used to record the 1 HNMR and 13 C NMR spectra, chemical shifts are based on residual protonated solvent. TMS (δ = 0.00 ppm) was used as an internal reference. 1 HNMR spectrum; recorded using CDCl3 (δ = 77.00 ppm) / DMSO-d6 (δ = 39.52 ppm) as an internal reference 13 C NMR spectroscopy. 1 HNMR and 13 C NMR peak type abbreviations: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, br = broad.

[0064] 3. Elemental analysis was performed using German Elementar Unicube & Shimadzu TOC-L, IR infrared detection was tested using Thermo Fisher Scientific Nicolet iS50, and UV lamp was tested using 365nm irradiation from Shanghai Shuyuan Analytical Instrument Factory.

[0065] 4. Special attention should be paid to the synthesis of TATP, DADP and HMTD. Keep the temperature low or at room temperature, perform small amounts and multiple times, make necessary explosion-proof preparations, eliminate static electricity and retain a small amount of water during purification to prevent danger.

[0066] 5. Other chemical related parts not described in detail in the examples of this application are all conventional technical contents.

[0067] (3) Overall synthesis route: linear synthesis

[0068] First, different ligands are synthesized (through a series of reactions of A and B), and then different ligands are combined with the metal core center by solvent thermal synthesis to obtain the desired MOF material under high pressure. Then, a membrane-dispersed polymer is added, and then a loaded acid is added, and the reaction is performed under high pressure again to finally obtain an acid-loaded inorganic salt sol, and its emission wavelength can be controlled by adding a nitride red phosphor. The linear synthesis route is shown below:

[0069]

[0070] (4) Implementation process of some typical molecules:

[0071] 1. Synthesis of compound SM1:

[0072]

[0073] R1=C6H 13 ;

[0074] General approach:

[0075] 1-Bromohexane (87.47 g, 529.9 mmol) was added dropwise to a stirred solution of azepane (49.97 g, 503.8 mmol) in ethanol (220 mL) cooled in an ice-water bath. Cesium carbonate (170.72 g, 524 mmol) was then added and the mixture was stirred vigorously at 0 ° C for 24 hours to reduce the formation of dialkylated products. The resulting suspension was filtered through a sand core funnel and the lower filtrate was concentrated under reduced pressure on a rotary evaporator at 40 ° C. A pale yellow suspension was thus obtained and vacuum distilled (80-95 ° C, 20 pa) to obtain the desired colorless liquid product SM1 (84.05 g, 91%).

[0076]

[0077] 1 H NMR: (CDCl3, 400MHz): δ (ppm) = δ2.62 (m) 1.64 (br, m) 1.59 (br, m); 13 C NMR: (CDCl3, 100MHz): δ (ppm) = δ55.7, 28.0, 27.1; HRMS: C 34 H 22 (M+H + ),Calculate:430.17;Find430.21. HRMS:calc.for C 12 H 26 N + :184.2060,Find 184.2072([M+H]+,100%). SM1 1 HNMR: The spectrum of CDCl3 distillation and drying is as follows Figure 3 shown.

[0078] 2. Synthesis of compound SM2:

[0079]

[0080] R1=C6H 13 , R2=CH3;

[0081] General approach:

[0082] Take a 250mL three-necked flask, add a stirrer, and connect a double-row tube for nitrogen protection. Add 20g SM1 (22.73g, 124mmol), add 100mL of acetone: ethyl acetate = 2:1 mixed solvent to dissolve, then add an excess of about 5% methyl bromide (12.44g, 131mmol) dissolved in 50mL acetone, react for 72 hours at ambient temperature, and then put the flask in a refrigerator for 24 hours. The obtained product is vacuum filtered and washed with a small amount of cold acetone. The obtained light yellow solid compound with methyl substituents is dried in a vacuum dryer or dried at 50°C in a vacuum oven for 24h. The yield of the obtained compound is shown in Table 1 below, and the purity is above 97%.

[0083]

[0084] 1 H NMR (400MHz, DMSO-d6): δ (ppm) = δ0.92 (t, J = 6.4Hz, 3H), 1.20-1.38 (m, 6H), 1. 55(m,2H),1.79(m,4H),2.48(t,J=6.8Hz,2H),3.03(s,3H),3.25-3.40(m,4H). 13 Calc.for C 13 H 28 IN:C,48.00;H,8.68;N,4.31%,Found:C,47.9;H,8.2;N,4.2%.HRMS;calc.for C 13 H 29 N + :199.2299,Find 199.2295([M+H]+,100%).

[0085] Table 1

[0086]

[0087]

[0088] The synthesis and purification methods of various other substituent salts are similar.

[0089] 3. Synthesis of compound MOF_A:

[0090]

[0091] X=OCH3, M=Sn; other X groups are similar, for example, X=N(CH3)2, CF3, OCOCH3, NHCOCH3, NCH3COCH3, etc.

[0092] General approach:

[0093] Take 50mL of anhydrous dichloromethane, protect with nitrogen, and use nitrogen bubbling method to bubble in the Shrek reaction bottle for half an hour to remove oxygen. Select a 200mL Hinville thick-walled pressure-resistant reaction bottle, weigh SMA (11.84g, 35mmol) and add it, use the above-mentioned pre-deoxygenated anhydrous dichloromethane (50mL) to dissolve, and under nitrogen protection, quickly add anhydrous SnBr2 (tin (II) bromide, 4.874g, 17.5mmol), under vigorous stirring, while keeping the temperature at room temperature and stirring for 24 hours, open the reaction bottle stopper, continue to maintain 40℃ for about 48h, cool to room temperature, filter and concentrate the filtrate, add a small amount of n-hexane or petroleum ether, collect and filter after a few days to obtain the light green solid product MOF_A (13.35g, 77%).

[0094]

[0095] 4. Synthesis of compound MOF_B:

[0096]

[0097] M=Sn,R1=C6H 13 , R2=CH3; other substituents are similar to the metal core center.

[0098] General approach:

[0099] First, prepare 50mL of a mixed solution of CH3CN:H2O=1:1, and use nitrogen bubbling for half an hour to remove oxygen. Select a 200mL Hinville thick-walled pressure-resistant reaction bottle, weigh SM2 (9.379g, 35mmol) and add it. Use the above-mentioned pre-deoxygenated CH3CN:H2O=1:1 mixed solvent (50mL) to dissolve it. Under nitrogen protection, quickly add anhydrous SnBr2 (tin bromide (II), 4.874g, 17.5mmol), and under vigorous stirring, keep the temperature at room temperature and slowly add HBr (48%, 35mL). Then heat it to 100℃ and stir for 24 hours, open the reaction bottle stopper, continue to maintain 100℃ for about 48h, then cool it down and slowly cool it to room temperature. Collect and filter the resulting yellow-green precipitate as MOF_B (11.44g, 81%). The MOF_B material itself and its excited fluorescent luminescence image are shown as follows. Figure 2 shown.

[0100]

[0101] 5. Preparation of gel using MOF_B:

[0102]

[0103] M=Sn,R1=C6H 13 , R2=CH3;

[0104] General approach:

[0105] Weigh about 10 g of PAM / PAN / PEG, and dissolve it in anhydrous DMSO / DMF (10 mL) at 60 °C under vigorous stirring. Then weigh anhydrous MOF_B (3 g) and add it. Raise and maintain the temperature to 80 °C, stir for 6 h, wait for the inorganic salt MOF and polymer to become gel, and cool to room temperature for use.

[0106]

[0107] In order to facilitate wavelength adjustment, commercial nitride red phosphor can be added in this step, and by adjusting the addition ratio, products with different excitation wavelengths as required can be achieved.

[0108] 6. Preparation of acid-loaded inorganic salt sol:

[0109]

[0110] M=Sn,R1=C6H 13 , R2=CH3; Taking polyphenylene sulfonic acid as an example:

[0111] General approach:

[0112] Take two 20mL glass bottles, add a stirrer, and measure 10mL (M w ~75000, 30wt.%inH2O) is dried in one of the bottles A to remove the water contained, and converted into a basically water-free polymer, and stirred vigorously; in another bottle B, about 5mL of the gel obtained in 5 is measured and heated to 60°C, and the sol is slowly dripped into bottle A until the dripping is completed, and its yellow-green fluorescence is observed by irradiating with a 365nm ultraviolet lamp. By changing the different proportions of the required acid, MOF salt and polymer in the above method until it contains stronger fluorescence, an acid-loaded inorganic salt sol is finally prepared. The schematic diagram of the acid-loaded inorganic salt sol, glass substrate luminescence and acrylic film luminescence is shown in the figure. Figure 1 shown.

[0113]

[0114] 7. Synthesis of explosive TATP:

[0115]

[0116] General approach:

[0117] Take a 250mL single-mouth flask and mix acetone (2mL, 27mmol) and hydrogen peroxide (2.5mL, 30%, 32mmol.). Keep the system at 0°C in an ice-water bath, slowly add concentrated sulfuric acid (5 drops), and continue stirring the mixture at room temperature for 6 hours, then add 2mL concentrated hydrochloric acid, and continue stirring at room temperature for 18h overnight. Collect the resulting precipitate by sand core filtration, be careful not to drain it completely without water to prevent explosion caused by static friction, etc., wash with distilled water to obtain TATP (4.86g, 81%) in the form of white crystals. This operation procedure can be expanded to the production level of tens of grams, and it is safe and efficient.

[0118]

[0119] 1 H NMR: (CDCl3, 400MHz): δ (ppm) = δ 1.43-1.49 (s, 18H), slightly contains 1 / 1000 acetone (TATP decomposition product). TATP 1 H NMR: The spectrum of CDCl3 1 / 1000 self-decomposition (1 / 1000 acetone) is as follows Figure 4 shown.

[0120] 8. Synthesis of explosive DADP:

[0121]

[0122] General approach:

[0123] Method A: TATP (0.5 g) was dissolved in anhydrous DCM, a catalytic amount of TsOH was added, and the mixture was stirred at room temperature for one week. After the reaction was completed, the solvent was removed under reduced pressure. The residue was recrystallized from hot methanol to obtain DADP compound (0.3 g) as a white powder.

[0124] Method B: In a 1L flask, add a mixture of acetone (62.5mL, 0.85mol), CH3OH (3mL) and DCM (250mL) and stir vigorously at room temperature for 10min. Then, cool the solution to -5°C and slowly add hydrogen peroxide (30%, 90mL, 0.88mol) over 15min. Continue stirring at the same temperature for 30 minutes and then cool to -20°C. Transfer the mixture to a separatory funnel, separate the organic layer, and use Molecular sieves (50 g, activated at 200 ° C for 24 h) were dried for 10 min and then filtered. In a 2L flask, DCM: CH3SO3H dichloromethane (175 mL: 35 mL) was added and cooled to -5 ° C. The dried organic mixture was added to this solution and stirred for 40 minutes. Subsequently, the mixture was transferred to a separatory funnel and washed three times with ice water (600 mL). The solvent was removed under reduced pressure to obtain a crude product of 24 g white powder. The crude product was recrystallized with hot methanol (per 1 g crude product / 12 mL MeOH) and dried under reduced pressure to obtain a purified compound DADP (20.5 g, yield 32%).

[0125]

[0126] 1 H NMR: (CDCl3, 400MHz): δ (ppm) = δ1.80 (s), 1.35 (s) ppm; 13 C NMR (CDCl3, 100MHz): δ (ppm) = 107.5, 22.4, 20.6. IR:2956,1375,1201,940,858,814,687cm - 1.

[0127] 9. Synthesis of Hexamethylenetetramine:

[0128]

[0129] General approach:

[0130] Take a 50mL single-necked flask, add a rotor, and place it in an oil bath. Then take 18mL of 36% to 38% formaldehyde aqueous solution (19.46g, 240mmol) and add it. Slowly add 28% to 30% NH3·H2O (hydrated ammonia, 9.11g, 10mL, 155mmol) in batches of 1mL each time. A large amount of heat is released. After the addition is completed, the mixture is heated to 35°C and reacted overnight for 12h. The water in it is dried by rotary evaporator the next day. The obtained solid is the product. It is slightly washed with ethanol and ethyl acetate to obtain white solid HMT (Urotropin, 5g, 92%). HMT 1 H NMR: The spectrum of CDCl3 is as follows Figure 5 shown.

[0131]

[0132] 10. Synthesis of explosive HMTD:

[0133]

[0134] General approach:

[0135] Take a 250mL single-necked flask, then add a rotor, stir slowly, and maintain a 0°C salt ice bath, measure hydrogen peroxide (5mL, 30%, 64mmol) and add it, weigh 2g (14.2mmol) of dried urotropine and add it, then weigh citric acid (3g, 15.6mmol) and add it in 6 times with an interval of 10min, stir for about 3h and return it to room temperature, then continue stirring for a total of 12h, a large amount of solid precipitates appear, and the obtained product is slowly filtered with a sand core funnel, and it is noted that there is no need to completely drain the water to prevent explosion caused by static electricity or friction, and wash with distilled water to obtain a solid product HMTD (1.219g, 82%).

[0136]

[0137] 1 H NMR: (CDCl3, 400MHz): 4.81 (s, 12H). HMTD 1 H NMR: CDCl3 spectrum to be prepared is as follows Figure 6 shown.

[0138] It should be noted that: since peroxide itself is easy to self-decompose at room temperature, the content in the purchased standard solution may be inaccurate, so it is chosen to be made and used according to the literature method (J.Am.Chem.Soc.2005,127,1146-1159.andJ.Phys.Chem.A,2001,105,8763-8768.), and the MOF material itself is solid and cannot be directly used in vapor thin film sensors. It can only be evaporated or prepared as a sol and then spin-coated into a film, so a specific method is required for preparation.

[0139] (5) Fluorescence test data:

[0140] 1. Solid UV absorption of MOF materials, such as Figure 7 The figure shows the in-situ UV absorption and excitation spectra of MOF_B material. MOF_B material itself has strong fluorescence, and the optimal excitation wavelength is about 360-370nm.

[0141] 2. Acid-loaded inorganic salt sol (MOF_B material as raw material), spin-coated on acrylic substrate, about 1 mg / mL, the best absorption wavelength is 360-370nm for fluorescence related tests, if necessary, commercial nitride red phosphor can be added to change the excitation wavelength. Figure 8 The figure shows the ultraviolet excitation spectrum of the acid-loaded inorganic salt sol. It can be seen that the fluorescence of the material itself is relatively stable when irradiated at 360-370nm, which meets the basic conditions for being used as a fluorescent probe.

[0142] 3. Acid-loaded inorganic salt sol (MOF_B material as raw material), acrylic substrate spin coating, 1 mg / mL, at 365nm excitation wavelength, heated conditions (80℃) explosive TATP (slightly heated to promote decomposition) fumigation / unfumigation test results. Fig. 9 The fluorescence quenching images of the obtained film stained with TATP and unstained are shown. It can be seen from the figure that the film material can undergo obvious fluorescence quenching when stained with peroxide explosive vapor, which means that it can sensitively test this type of explosive.

[0143] Note: exc_x nm means x nm test at room temperature, exc_y s means ys test of fumigated explosive under heating condition (80℃), for example, exc_360nm means 360nm test at room temperature, spin coating 1mg / mL concentration for excitation, and so on; exc_3s means 365nm fumigated explosive test for 3s under heating condition (80℃), still spin coating 1mg / mL concentration for excitation, and so on.

[0144] (6) Explosive response data:

[0145] Test method:

[0146] 1. Spin coating: Heat the prepared acid-loaded inorganic salt sol to 50°C and keep it for 10 minutes before use. Use the test equipment and auxiliary components described in our company's patent CN105866091A / CN201720381260.7 / CN214584899U to spin the acid-loaded inorganic salt sol (very viscous) on a spin coater at a speed of 1500 rpm / min for a total time of 3 seconds. Spin it on a quartz wafer (Φ=5 mm) and use it after making a thin film. Consider covering it with spin coating again. The second change time is 5 seconds, for a total of two times.

[0147] 2. Drop casting method: Heat the prepared acid-loaded inorganic salt sol to 50°C and maintain for 10 min, attach it to the acrylic substrate by drop casting, and then age it in a vacuum dryer at 90°C for 24 h before use.

[0148] 3. Temperature dependence: The fluorescence spectrum was measured at different temperatures. As the temperature increased, the fluorescence intensity of the film increased slightly and then slowly decayed. When the internal cavity temperature was 50°C, the fluorescence intensity of the film decreased by 40%, and then continued to slowly decrease, then slowly increased, and then stabilized. This result proves that the film is stable to temperature and air. Fig.10 As shown (the temperature inside the cavity is 50°C).

[0149] 4. Preparation of explosive standard solution: Weigh 10 mg of TATP / DADP / HMTD using a 1 / 10,000 internally calibrated four-decimal analytical balance, and prepare it with 10 mL of anhydrous dichloromethane to make a standard solution of 1 μg / μL = 1000 ng / μL. Then take out 1 mL and add it to 9 mL of anhydrous dichloromethane to dilute it tenfold to obtain a standard solution of 100 ng / μL. Repeat the above operation to dilute it 10 times to obtain a final standard solution of 10 ng / μL for standby use.

[0150] 5. Test results: Test the response images of different types of explosives. Figure 11-17 The acid-loaded inorganic salt sol material of the present application can not only prepare a good membrane, but also be applied in the field of peroxide explosive vapor sensing, and has a very good response to TATP, DADP, HMTD, and di-tert-butyl hydroperoxide. In particular, taking TATP as an example, it can even respond to a trace test as low as 10ng sensitivity.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A MOF material, characterized in that: The MOF material is linked with metal ions or inorganic clusters as nodes and organic ligands as connectors. The structure of the MOF material consists of 2 ligands, 1 metal core center, and 4 / 2 halogen ligands. The structural formula of the MOF material is as follows: Wherein, Ligand_A and Ligand_B are both organic ligands; X is Cl or Br; M is selected from at least one of Pb, Zn, Cd, Mn, Sb, Ge, and Sn, and the M salt is a chloride metal salt or a bromide metal salt.

2. The MOF material according to claim 1, characterized in that The Ligand_A is a neutral ligand, and its structural formula is shown below: Wherein, Ar is a substituted phenyl group or a phenyl group, and the substituent in the substituted phenyl group is selected from at least one of OCH3, N(CH3)2, CF3, OCOCH3, NHCOCH3, and NCH3COCH3; Wherein, Z represents -NN-, and N represents an aryl group or a condensed ring, the aryl group is selected from one of a para-disubstituted trifluoromethylphenyl, a dimethylaminophenyl, and a halogenated phenyl, and the condensed ring is selected from one of naphthalene, anthracene, phenanthrene, phenazine, and phenoxazine; The Ligand_B is an ionic liquid containing N, S, and P, and its structural formula is as follows: Wherein, R1, R2, R3, R4 are each independently selected from alkyl C n H 2n+1 , alkenyl C n H 2n-1 , alkynyl C n H 2n-3 At least one of aryl, fluorenyl, n is 1-25 and n is an integer.

3. A method for preparing the MOF material according to claim 1 or 2, characterized in that: The steps include: First, different ligands are synthesized, and then the different ligands are reacted with the metal core center through solvothermal reaction to obtain MOF materials.

4. A method for preparing an acid-loaded inorganic salt sol capable of cyclically detecting peroxide explosives, characterized in that: Utilizing the MOF material according to claim 1 or 2, comprising the following steps: The MOF material and the membrane-dispersed polymer are dissolved in a solvent so that the membrane-dispersed polymer wraps the MOF material, and a gel is obtained after uniform mixing; an acid is added to the gel to react so that the acid is loaded on the gel to obtain an acid-loaded inorganic salt sol.

5. The method for preparing the acid-loaded inorganic salt sol for cyclically detectable peroxide explosive according to claim 4, characterized in that: The acid is at least one of an inorganic acid, a heteropoly acid, and an organic acid; and the membrane-dispersed polymer is at least one of PAM, PAN, and PEG.

6. The method for preparing the acid-loaded inorganic salt sol for cyclically detectable peroxide explosive according to claim 4, characterized in that: Nitride red phosphor is added to the acid-loaded inorganic salt sol to adjust its color emission wavelength.

7. The method for preparing the acid-loaded inorganic salt sol for cyclically detectable peroxide explosive according to claim 4, characterized in that: The solvent is DMSO and / or DMF.

8. A vapor sensing membrane, characterized in that: The acid-loaded inorganic salt sol prepared by the preparation method according to any one of claims 4 to 7 comprises the following steps: The acid-loaded inorganic salt sol is prepared into a vapor sensing membrane by drop casting or spin coating.

9. Use of the vapor sensing membrane according to claim 8 in the detection of peroxide explosives.

10. The use according to claim 9, characterized in that: The peroxide explosive is selected from at least one of triacetone triperoxide, diacetone diperoxide, hexamethylene triperoxide diamine, and tetramethylene diperoxide diurea.

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