A method of detecting picric acid

Abstract

The application discloses a polydiphenylacetylene derivative capable of rapidly detecting nitrobenzene explosives, a synthesis method and application thereof, and is characterized in that, in view of the electron-deficient characteristics of the nitrobenzene explosives, a polydiphenylacetylene derivative with rich active sites and strong electron-donating capacity is designed to achieve the purpose of rapidly and accurately detecting the nitrobenzene explosives, and an ultrathin fluorescent polymer sensing probe is designed, which is more conducive to the penetration of the analyte through the whole film and achieves good sensing effect. The polydiphenylacetylene derivative fluorescent probe synthesized by the application has high fluorescence intensity, high detection sensitivity and fast detection speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polymer fluorescent material sensors, and in particular to a polydiphenylacetylene derivative capable of rapidly detecting nitrobenzene explosives, a synthesis method and applications thereof. BACKGROUND

[0002] The most common explosives at present mainly include the following three types: peroxide, diazonium salt compound and nitrobenzene compound. The most widely used is nitrobenzene explosive, and the polynitro aromatic hydrocarbon compound has extremely strong explosiveness, so it is particularly important to detect 2, 4, 6-trinitrotoluene (TNT), nitrobenzene (NB), p-nitrotoluene (NT), 2, 6-dinitrotoluene (DNMT), 2, 4, 6-trinitrophenol (PA) and other polynitrobenzene explosives. The detection techniques for nitrobenzene explosives include chromatography-mass spectrometry, colorimetry, electrochemistry, surface plasmon resonance, chemiluminescence enzyme-linked immunoassay and the like, but the above detection methods have the disadvantages of long detection time, detection instrument not easy to carry, high detection cost and the like. The fluorescence detection method is relatively fast, low in detection cost and convenient to carry compared with other methods, and some researchers prepare the fluorescence sensing film for application in the detection of explosives: for example, some researchers prepare a double-emission type electro-polymerized film by successively depositing TCPC molecules with blue fluorescence emission and TCBzC molecules with green emission on ITO glass through electro-polymerization, but the preparation process of the electro-polymerized film is complex, the electro-polymerization conditions need to be accurately controlled, and the stability and repeatability of the film may be affected by the environment; some researchers prepare a low-molecular-weight diphenylsilane film self-assembled on a glass substrate, which can detect ultra-trace TNT and DNT, but there is no relevant experimental data to support the detection of picric acid PA; some researchers design and synthesize two fluoranthene derivatives TPFA and PO-TPFA with a "propeller" structure, but the synthesis steps of the fluoranthene derivatives with the "propeller" structure are complex and the cost is high. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a polydiphenylacetylene derivative capable of rapidly detecting nitrobenzene explosives, a synthesis method and applications thereof, and the specific technical solutions are as follows:

[0004] A polydiphenylacetylene derivative capable of rapidly detecting nitrobenzene explosives has the following structural formula:

[0005] or or; ;

[0006] Wherein, the imidazole unit in the three structural formulae is 1-alkyl imidazole, 1-alkyl 3-methyl imidazole and 1-alkyl-2,3-dimethyl imidazole respectively; wherein the alkyl is selected from any one of methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl; the anion X is selected from any one of chloride ion, bromide ion, iodide ion, tetrafluoroborate ion, hexafluorophosphate ion, acetate ion, bis-trifluoromethanesulfonylimide ion, nitrate ion, perchlorate ion, hydrogen sulfate ion, dihydrogen phosphate ion, trifluoromethanesulfonate ion, trifluoroacetate ion, p-toluenesulfonate ion, alkyl, amino, hydroxyl, alkoxy, trifluoromethanesulfonate group.

[0007] A preparation method of a polydiphenylacetylene derivative capable of rapidly detecting nitrobenzene explosives, comprising the following steps:

[0008] (1) mixing dichlorobis(triphenylphosphine)palladium, cuprous iodide and triphenylphosphine in a molar ratio of 1:2:2 to obtain a catalyst, adding trimethylsilyl acetylene and 1-bromo-4-trimethylsilylbenzene in a volume ratio of 1:1, and then adding tetrahydrofuran and triethylamine, and stirring and heating at 60-80 ℃ for 6-12 h, to obtain a product trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane after post-treatment;

[0009] (2) adding trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane and potassium carbonate in a molar ratio of 1:4 into methanol, stirring at room temperature for 2-6 h to make them completely dissolved and react, and obtaining a product (4-ethylphenyl)trimethylsilane after post-treatment;

[0010] (3) adding 4-iodophenethyl alcohol, dichlorobis(triphenylphosphine)palladium, triphenylphosphine and cuprous iodide in a molar ratio of 360:1:4:5.5 into triethylamine to obtain a mixed solution one; at the same time, dissolving (4-ethylphenyl)trimethylsilane in triethylamine to obtain a mixed solution two; mixing and stirring the mixed solution one and the mixed solution two in an inert gas atmosphere at room temperature according to a molar ratio of (4-ethylphenyl)trimethylsilane to 4-iodophenethyl alcohol of 1.2:1, and obtaining 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene after cooling to room temperature and post-treatment;

[0011] (4) adding 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene, carbon tetrabromide and triphenylphosphine in a molar ratio of 1:1.2:1.2 into anhydrous ether, stirring and reacting at room temperature for 6-12 h, and obtaining a white needle-shaped polymer monomer after post-treatment;

[0012] (5) polymerizing the white needle-shaped polymer monomer obtained in step (4) to obtain a polydiphenylacetylene derivative precursor;

[0013] (6) The polydibenzotetrafulvalene derivative precursor obtained in step (5) is reacted with 1-alkyl imidazole, 1-alkyl 3-methyl imidazole, and 1-alkyl-2,3-dimethyl imidazole, respectively, to attach the imidazole unit to the polydibenzotetrafulvalene chain, to obtain a product; the product is reacted with lithium bis-trifluoromethyl sulfonimide in a methanol solution, and post-processing is performed to obtain the polydibenzotetrafulvalene derivative.

[0014] A fluorescent probe made of a polydibenzotetrafulvalene derivative capable of rapidly detecting nitrobenzene explosives.

[0015] A method for preparing a fluorescent probe capable of rapidly detecting nitrobenzene explosives by using a polydibenzotetrafulvalene derivative, comprising the following steps:

[0016] S1: The silicon wafer is cleaned with a first organic solvent and deionized water to remove dust and particle contaminants on the surface, and then vacuum dried;

[0017] S2: The polydibenzotetrafulvalene derivative is dissolved in a second organic solvent, and after ultrasonic treatment, a polydibenzotetrafulvalene derivative solution of 2-8 mg / mL is obtained;

[0018] S3: The polydibenzotetrafulvalene derivative solution obtained in step S2 is uniformly dropped and coated on the surface of the silicon wafer obtained in step S1, and a high-speed spin coating instrument is used to rotate to obtain a silicon wafer with a uniform polydibenzotetrafulvalene derivative coating on the surface;

[0019] S4: The silicon wafer coated with the polydibenzotetrafulvalene derivative obtained in step S3 is placed in an oven for drying, so that the organic solvent on the silicon wafer volatilizes, to obtain the fluorescent probe.

[0020] Further, the second organic solvent is selected from any one of acetone, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, and methanol.

[0021] The detection principle of using the polydibenzotetrafulvalene derivative as a fluorescent probe for nitrobenzene explosive detection is as follows: The recognition unit of the polydibenzotetrafulvalene derivative is an imidazole cation, which can form a strong electrostatic interaction with the nitro explosive molecule, the signal sensing unit is a diphenyl ethylene group, which is connected by an alkyl chain, so that the diphenyl ethylene and the imidazole group and its ion are in the same plane, forming a π-π conjugated molecular wire structure, which can emit very strong yellow-green fluorescence. The polydibenzotetrafulvalene derivative has strong electron-donating ability and can combine with electron-deficient nitro explosives, and static quenching and dynamic quenching exist simultaneously in the fluorescence detection process, so that the nitro explosives can be rapidly and sensitively detected.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1.The polydiphenylacetylene derivative of the present application is an important luminescent material due to its unique pi-pi conjugated molecular wire structure;

[0024] 2.The fluorescent probe containing the polydiphenylacetylene derivative prepared by the present application has high fluorescence intensity and high detection sensitivity, and is a good fluorescent material for detecting nitrobenzene explosives;

[0025] 3.The present application has fast detection speed and is convenient to use, and the explosive detector can display the fluorescence intensity in real time, and the real-time monitoring of nitrobenzene explosives can be realized according to the fluorescence drop value, so that the present application can be used for detecting nitrobenzene explosives in water environment systems and solid systems, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a Fourier transform infrared spectrum of the polydiphenylacetylene derivative.

[0027] Figure 2 It is a fluorescence emission spectrum of the polydiphenylacetylene derivative in different organic solutions.

[0028] Figure 3 It is a fluorescence probe prepared by the polydiphenylacetylene derivative prepared in Example 1, and the observation result under the 20 times lens of the optical microscope.

[0029] Figure 4 It is a fluorescence intensity change graph of the sensing probe of the polydiphenylacetylene derivative when detecting picric acid in the explosive detector.

[0030] Figure 5 It is a stability test graph of the sensing probe of the polydiphenylacetylene derivative in the explosive detector. DETAILED DESCRIPTION

[0031] The present application will be described in detail below according to the drawings and preferred embodiments, and the purposes and effects of the present application will become more apparent, and it should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0032] Example 1

[0033] The reaction process for preparing the polydiphenylacetylene derivative in the present embodiment is as follows:

[0034] (1) Put 21 mg of dichlorobis(triphenylphosphine) palladium, 11.4 mg of cuprous iodide and 15.7 mg of triphenylphosphine (molar ratio of 1:2:2) into a double-tube as a catalyst, inject 3 mL of super dry tetrahydrofuran and 3 mL of triethylamine using a syringe, then inject 0.5 mL of ethynyltrimethylsilane and 0.5 mL of 1-bromo-4-trimethylsilylbenzene, and stir and heat at 70°C under nitrogen protection for 12 h, and obtain the product trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane after post-processing;

[0035] (2) Put 0.62 g of trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane and 1.38 g of potassium carbonate (molar ratio of 1:4) into a round-bottom flask, add 10 mL of methanol, and stir at room temperature for 5 h, and obtain the product (4-ethylphenyl)trimethylsilane after post-processing;

[0036] (3) Put 12.4 g of 4-iodophenethyl alcohol, 0.0964 g of dichlorobis(triphenylphosphine) palladium, 0.157 g of triphenylphosphine and 0.149 g of cuprous iodide into a three-necked flask, then add 150 mL of triethylamine to stir and obtain a mixed solution one; at the same time, dissolve 11.2 g of (4-ethylphenyl)trimethylsilane in 50 mL of triethylamine to obtain a mixed solution two; then mix the mixed solution one and the mixed solution two, stir and reflux under nitrogen for 24 h, cool to room temperature, and obtain 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene after post-processing operations such as extraction, column chromatography and recrystallization;

[0037] (4) Put 4.4 g of 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene, 6.1 g of carbon tetrabromide and 4.7 g of triphenylphosphine (molar ratio of 1:1.2:1.2) in 100 mL of anhydrous ether at room temperature for 12 h, and obtain a white needle-shaped polymer monomer after post-processing;

[0038] (5) Polymerize the white needle-shaped polymer monomer to obtain a polydiacetylene derivative precursor;

[0039] (6) React the polydiacetylene derivative precursor obtained in step (5) with 1-methylimidazole to attach imidazole units to the side chain of the polydiacetylene, obtain the product, and then react it with lithium bis(trifluoromethylsulfonyl)imide in a methanol solution to obtain a polydiacetylene derivative after post-processing.

[0040] In order to explore the structural characteristics of the polydiacetylene derivative and the influence of solvent effect on its optical properties, the chemical structure of the polydiacetylene derivative obtained in Example 1 was systematically characterized by Fourier transform infrared spectroscopy (FTIR), and the results are shown in Figure 1 Figure 1 ​From the infrared spectrum, it can be seen that the synthesized polymer is a polyphenylenevinylene derivative.

[0041] Further, to illustrate the regulation of solvent polarity on the fluorescence properties of polyphenylenevinylene derivatives, acetone, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide and methanol are selected as the solvent system, and the fluorescence intensity change is analyzed by fluorescence spectroscopy, which proves that the strong polarity solvent has a significant regulation mechanism on the luminescent properties of the conjugated polymer, and the results are shown in Figure 2 .

[0042] Example 2

[0043] (1) Put 42 mg of dichlorobis(triphenylphosphine)palladium, 22.8 mg of cuprous iodide and 31.4 mg of triphenylphosphine into a double-tube as a catalyst, inject 6 mL of ultradry tetrahydrofuran and 6 mL of triethylamine using a syringe, then inject 3 mL of ethynyltrimethylsilane and 3 mL of 1-bromo-4-trimethylsilylbenzene, and stir and heat under nitrogen protection at 70°C for 8 h, and after post-treatment, the product trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane is obtained;

[0044] (2) Put 1.24 g of trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane and 2.76 g of potassium carbonate into a round-bottom flask, add 10 mL of methanol, stir at room temperature for 4 h, and after post-treatment, the product (4-ethylphenyl)trimethylsilane is obtained

[0045] (3) Put 24.8 g of 4-iodophenethyl alcohol, 0.1928 g of dichlorobis(triphenylphosphine)palladium, 0.314 g of triphenylphosphine and 0.3 g of cuprous iodide into a three-necked flask, then add 150 mL of triethylamine, and then add 50 mL of triethylamine dissolving 22.4 g of (4-ethylphenyl)trimethylsilane, stir and reflux under nitrogen for 24 h, cool to room temperature, and after post-treatment operations such as extraction, column passing and recrystallization, 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene is obtained;

[0046] (4) Put 8.8 g of 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene, 12.2 g of carbon tetrabromide and 9.4 g of triphenylphosphine into 100 mL of anhydrous diethyl ether at room temperature for 12 h, and after post-treatment, a white needle-shaped polymer monomer is obtained;

[0047] (5) The white needle-shaped polymer monomer is subjected to a polymerization reaction to obtain a polyphenylenevinylene derivative precursor

[0048] (6) The polydiacetylene derivative precursor obtained in step (5) is reacted with 1-methylimidazole to attach imidazole units to the polydiacetylene chain, and the product is reacted with lithium bis(trifluoromethylsulfonyl)imide in a methanol solution to obtain the polydiacetylene derivative after work-up.

[0049] Example 3

[0050] The reaction process for preparing the polydiacetylene derivative in this example is as follows:

[0051] (1) 21 mg of bis(triphenylphosphine)palladium dichloride, 11.4 mg of cuprous iodide, and 15.7 mg of triphenylphosphine are placed into a double-tube as a catalyst, 3 mL of ultradry tetrahydrofuran and 3 mL of triethylamine are injected using a syringe, followed by injection of 0.5 mL of ethynyltrimethylsilane and 0.5 mL of 1-bromo-4-trimethylsilylbenzene, and the mixture is stirred and heated at 70°C under nitrogen protection for 12 h, and the product trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane is obtained after work-up.

[0052] (2) 0.62 g of trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane and 1.38 g of potassium carbonate are placed into a round-bottom flask, 10 mL of methanol is added, and the mixture is stirred at room temperature for 5 h, and the product (4-ethylphenyl)trimethylsilane is obtained after work-up.

[0053] (3) 12.4 g of 4-iodophenethyl alcohol, 0.0964 g of bis(triphenylphosphine)palladium dichloride, 0.157 g of triphenylphosphine, and 0.149 g of cuprous iodide are added into a three-necked flask, followed by addition of 150 mL of triethylamine, and then 50 mL of triethylamine in which 11.2 g of (4-ethylphenyl)trimethylsilane is dissolved is added, and the mixture is stirred and refluxed under nitrogen for 24 h, and the mixture is cooled to room temperature, and the product 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene is obtained after work-up operations such as extraction, column chromatography, and recrystallization.

[0054] (4) 4.4 g of 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene, 6.1 g of carbon tetrabromide, and 4.7 g of triphenylphosphine are reacted in 100 mL of anhydrous diethyl ether at room temperature for 12 h, and a white needle-shaped polymer monomer is obtained after work-up.

[0055] (5) The white needle-shaped polymer monomer is subjected to a polymerization reaction to obtain a polydiacetylene derivative precursor.

[0056] (6) The bromoethyl group in the polydiacetylene derivative precursor obtained in step (5) is reacted with 1-methyl 3-methylimidazole to attach imidazole units to the polydiacetylene chain, and the product is reacted with lithium bis(trifluoromethylsulfonyl)imide in a methanol solution to obtain the polydiacetylene derivative after work-up.

[0057] Example 4

[0058] The reaction process for preparing the polydiphenylacetylene derivative in this example is as follows:

[0059] (1) Put 21 mg of bis-triphenylphosphine palladium dichloride, 11.4 mg of cuprous iodide, and 15.7 mg of triphenylphosphine into a double-tube as a catalyst, inject 3 mL of super-dry tetrahydrofuran and 3 mL of triethylamine using a syringe, then inject 0.5 mL of ethynyltrimethylsilane and 0.5 mL of 1-bromo-4-trimethylsilylbenzene, and stir and heat under nitrogen protection at 70°C for 12 h, and obtain the product trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane after post-treatment;

[0060] (2) Put 0.62 g of trimethyl(4-(trimethylsilyl)ethyl)phenyl)silane and 1.38 g of potassium carbonate into a round-bottom flask, add 10 mL of methanol, stir at room temperature for 5 h, and obtain the product (4-ethylphenyl)trimethylsilane after post-treatment

[0061] (3) Put 12.4 g of 4-iodophenethyl alcohol, 0.0964 g of bis-triphenylphosphine palladium dichloride, 0.157 g of triphenylphosphine, and 0.149 g of cuprous iodide into a three-necked flask, then add 150 mL of triethylamine, and then add 50 mL of triethylamine in which 11.2 g of (4-ethylphenyl)trimethylsilane is dissolved, stir and reflux under nitrogen for 24 h, cool to room temperature, and obtain 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene after post-treatment operations such as extraction, column chromatography, and recrystallization;

[0062] (4) React 4.4 g of 1-(p-trimethylsilyl)phenyl-2-(p-hydroxyethyl)phenylacetylene, 6.1 g of carbon tetrabromide, and 4.7 g of triphenylphosphine in 100 mL of anhydrous diethyl ether at room temperature for 12 h, and obtain a white needle-shaped polydiphenylacetylene derivative precursor after post-treatment;

[0063] (5) Polymerize the white needle-shaped polymer monomer to obtain a polydiphenylacetylene derivative precursor;

[0064] (6) React the bromoethyl groups in the polydiphenylacetylene derivative precursor obtained in step (5) with 1-methyl-2,3-dimethylimidazole, respectively, attach the imidazole units to the polydiphenylacetylene chain to obtain a product, and react the product with sodium trifluoromethanesulfonate in a methanol solution to obtain a polydiphenylacetylene derivative after post-treatment.

[0065] Example 5

[0066] The detection steps of the fluorescent probe obtained from the polydiphenylacetylene derivative prepared above for detecting nitrobenzene explosives are as follows:

[0067] (1) The silicon wafer is cleaned with organic solvent and deionized water to remove dust and particle contaminants on the surface, and is dried in a vacuum drying oven and placed for use;

[0068] (2) The poly (diphenylacetylene) derivative obtained in Example 1 is dissolved in methanol, and is completely dissolved by ultrasonic at room temperature to prepare a poly (diphenylacetylene) derivative solution of 8 mg / mL;

[0069] (3) The poly (diphenylacetylene) derivative solution obtained in step (2) is uniformly dropped and coated on the surface of the cleaned silicon wafer obtained in step (1), and is rotated by a spin coater under the condition of 1000 r / min and 40 s to obtain a silicon wafer uniformly coated with poly (diphenylacetylene) derivative on the surface;

[0070] (4) The silicon wafer coated with poly (diphenylacetylene) derivative obtained in step (3) is placed in a 80 ℃ vacuum drying oven for drying for 24 h to volatilize the organic solvent on the silicon wafer, and a fluorescent probe of poly (diphenylacetylene) derivative is obtained. The observation result of the fluorescent probe obtained in this example under 20 times magnification of an optical microscope is shown in FIG. 1, and it can be seen from FIG. 1 that the poly (diphenylacetylene) material coating film attached to the silicon wafer has good void rate reduction and π-π stacking, which is beneficial to the detection of explosive gas. Figure 3 Figure 3

[0071] (5) The silicon wafer containing poly (diphenylacetylene) derivative dried in step (4) is used as a fluorescent probe and is placed in an explosive detector, and the fluorescence intensity of the detection system changes with the concentration of nitrobenzene explosive, and the presence of nitrobenzene explosive is determined according to the size of the fluorescence quenching value.

[0072] The use method of the explosive detector is as follows: (1) the sampling paper is dipped in the nitrobenzene explosive or the solution containing the nitrobenzene explosive is dropped on the sampling paper, and the solution is volatilized completely; (2) the sampling paper containing the nitrobenzene explosive is inserted into the explosive detector; (3) whether the explosive exists is determined according to the fluorescence intensity displayed by the explosive detector.

[0073] Further, the detection sensitivity and the detection limit can be calculated according to the change of the fluorescence intensity in the explosive detector with the concentration of the explosive.

[0074] Examples 6-9

[0075] The steps are the same as those in Example 5, except that the second organic solvent in step (2) is different, and the second organic solvents in Examples 6-9 are dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile and acetone, respectively.

[0076] ​​The detection method of nitrobenzene explosive using the fluorescent probe obtained from Example 5 was used to detect the explosive picric acid:

[0077] The dried silicon wafer containing poly (diphenylacetylene) derivatives was cut into small silicon pieces of 4 mm*4 mm as fluorescent sensing probes and placed into the explosive detector. Reducing the size of the fluorescent sensing probe is more conducive to saving detection costs and expanding product application range. Then, the sampling paper was dipped into the solution containing nitrobenzene explosive or the solution containing nitrobenzene explosive was dropped on the sampling paper. After the solution was completely volatilized, the sampling paper was inserted into the explosive detector. Whether the explosive existed was determined according to the fluorescence intensity displayed by the explosive detector. As shown in Figure 4 , the real-time fluorescence intensity change of the fluorescent sensing probe containing poly (diphenylacetylene) derivatives placed in the explosive detector to detect picric acid was shown. Regions a and c represent the fluorescence intensity self-decay curve of the fluorescent polymer sensing probe over time, and region c also represents the fluorescence change of the sensor after detecting the explosive, and the fluorescence intensity obviously rises from the lowest point of detecting the explosive. Region b represents the fluorescence intensity change of the fluorescent polymer sensing probe when it reacts with 1500 ng / μL picric acid. Region d represents the fluorescence intensity change of the fluorescent polymer sensing probe when it reacts with 3000 ng / μL picric acid. Points 1 and 2 are the moment when the explosive is detected by the sensing probe containing poly (diphenylacetylene) derivatives. Due to the fluorescence quenching reaction between the explosive and poly (diphenylacetylene) derivatives, the fluorescence intensity rapidly decreases. From the fluorescence intensity change in the figure, it can be concluded that the fluorescent polymer sensing probe prepared by containing poly (diphenylacetylene) derivatives can well detect nitrobenzene explosive.

[0078] In order to further ensure the stability of the fluorescent sensing material, the fluorescent probe prepared by the preparation method of the nitrobenzene explosive probe in Example 5 was tested empty without inserting the sampling paper containing the explosive, as shown in Figure 5 : Regions a and c represent the fluorescence change curve of the fluorescent polymer sensing probe under the condition of not adding the explosive for empty testing. Region b represents the fluorescence intensity self-decay curve of the fluorescent polymer sensing probe over time. The stability test mainly compares whether the fluorescence intensity of region a and region c decreases consistently under the condition of empty testing after the fluorescence self-decay in region b. After comparing the fluorescence intensity decrease value of region a and region c in Figure 5 , the fluorescence decrease value meets the requirement of consistency. Therefore, it can be concluded that the fluorescent sensing probe containing poly (diphenylacetylene) derivatives prepared by us has good stability and meets the experimental requirements.

[0079] Those skilled in the art can understand that the above description is only the preferred examples of the present application and is not used to limit the present application, and although the present application is described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features. Any modification, equivalent replacement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting picric acid, characterized in that, Includes the following steps: (1) Clean the silicon wafer with organic solvent and deionized water to remove dust and particulate contaminants from the surface, and dry it in a vacuum drying oven for later use; (2) Dissolve the polydiphenylacetylene derivative in methanol and sonicate it at room temperature to completely dissolve it, so as to prepare a polydiphenylacetylene derivative solution of 8 mg / mL. (3) After uniformly drop-coating the polydiphenylacetylene derivative solution obtained in step (2) onto the cleaned silicon wafer surface obtained in step (1), the silicon wafer with a uniformly coated polydiphenylacetylene derivative is obtained by spin coating at 1000 r / min and 40 s. (4) Place the silicon wafer coated with polydiphenylacetylene derivative obtained in step (3) into an 80 °C vacuum drying oven and dry for 24 h to allow the organic solvent on the silicon wafer to evaporate. (5) Cut the dried silicon wafer containing polydiphenylacetylene derivative into small silicon wafers of 4 mm*4 mm as fluorescent sensing probes and put them into the explosive detector. Then, use sampling paper to dip into the picric acid or drop the picric acid solution onto the sampling paper and wait for the solution to evaporate completely before inserting it into the explosive detector. Determine whether the explosive exists based on the fluorescence intensity displayed by the explosive detector. The structural formula of the polydiphenylacetylene derivative is: 。

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