Preparation method and application of flexible fluorescent sensing film based on fluorescent probe

Abstract

The invention discloses a preparation method of a flexible fluorescent sensing film based on a fluorescent probe, which is characterized in that molecules of the fluorescent probe take a 1, 8-naphthalimide derivative as a core unit, azetidine modified naphthylacetylene is introduced to one end of the core unit, and alkyl chains with different lengths are keyed into the other end of the core unit through condensation reaction; the preparation method comprises the following steps: uniformly mixing a fluorescent probe and cellulose triacetate by adopting a physical mixing method to prepare a spinning solution, and preparing the flexible fluorescent sensing film by adopting an electrostatic spinning technology. The preparation method of the flexible fluorescent sensing film based on the fluorescent probe is used for sensitive detection of peroxide explosives TATP.

Description

Technical Field

[0001] The invention belongs to the technical field of hidden explosive detection, and in particular relates to a preparation method and application of a flexible fluorescent sensor film based on a fluorescent probe. Background Art

[0002] TATP (triacetone triperoxide, chemical formula C9H6O6) is a high-energy compound, also known as triacetone triperoxide. It is a white or pale yellow crystal that is highly explosive and sensitive, so extreme caution is required when handling and storing it. In contrast to its destructive power, the preparation of TATP is relatively simple and can be directly generated by the reaction of hydrogen peroxide (H2O2) and acetone (C3H6O) under acidic conditions. The explosiveness of TATP mainly comes from the peroxide bonds in its molecules. Such chemical bonds are easily broken when subjected to impact, friction or high temperature, resulting in rapid decomposition and the release of large amounts of gas and energy, thereby causing an explosion. Because it is easy to prepare, has great destructive power and does not contain nitrogen, it can easily escape detection by most explosives detectors, so TATP is one of the key inspection objects in safety inspections.

[0003] Fluorescent molecular probe technology has gradually become an important means of detecting trace amounts of high-risk chemicals due to its advantages such as high sensitivity and fast response speed. The fluorescent sensor film prepared by fixing the sensor unit on the surface of a flexible matrix by physical or chemical methods is a trace substance detection device with great development potential. It has the advantages of simple operation, easy to carry, adjustable size and no pollution to the test system. It has a great promoting effect on the research of smart wearable materials that has attracted widespread attention. In particular, the nanofiber fluorescent sensor film prepared by combining fluorescent sensing technology with electrospinning technology has been a hot topic in recent years.

[0004] TATP has poor stability at room temperature and is easily decomposed into acetone and H2O2. Therefore, researchers often detect TATP by detecting acetone or H2O2. For example, the research group of Cheng Jiangong and He Qingguo from the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences developed a new type of fluorescent hyperbranched polymer with a boronate-terminated pyrene-fluorene alternating copolymer skeleton, which can achieve rapid and sensitive detection of TATP through sensitive response to H2O2 vapor. The research group of Fang Yu from Shaanxi Normal University synthesized a fluorescent compound (DNNDI) based on the naphthalene diimide structure and used it in the preparation of fluorescent sensing film. They successfully developed a low-cost, highly sensitive, portable and reusable paper-based fluorescent sensor for detecting TATP through vapor sampling.

[0005] Although film-based fluorescent sensors have made some progress in the field of explosive detection, there are still many problems, such as the limited types of explosives that can be detected, the poor photochemical stability of the film, and the low ability to distinguish and identify complex samples. Therefore, it is urgent to develop a fluorescent sensing film with good photochemical stability, reusability, and strong anti-interference ability, and to accelerate the deviceization and integration of film-based fluorescent sensors to promote their industrial application. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a flexible fluorescent sensor film based on a fluorescent probe for sensitive detection of peroxide explosives TATP.

[0007] In order to solve the above technical problems, the present invention discloses a method for preparing a flexible fluorescent sensor film based on a fluorescent probe. The molecule of the fluorescent probe is based on a 1,8-naphthalimide derivative as a core unit, an azetidine-modified naphthylacetylene is introduced at one end, and an alkyl chain of different lengths is typed at the other end through a condensation reaction; the fluorescent probe is evenly mixed with triacetyl cellulose by a physical mixing method to prepare a spinning solution, and a flexible fluorescent sensor film is prepared by an electrostatic spinning technology; the structural formula of the fluorescent probe is as follows:

[0008]

[0009] In the structural formula, n is 1, 2, 3 or 4.

[0010] The technical solution of the present invention also has the following characteristics:

[0011] As a preferred embodiment of the present invention, the synthesis of the fluorescent probe is specifically carried out according to the following steps:

[0012] Step 1, synthesizing compound N2: weigh 6-bromo-2-naphthol and place it in a round-bottom flask, add redistilled dichloromethane and anhydrous pyridine, add trifluoromethanesulfonate dropwise to the reaction solution under ice bath conditions, and stir at room temperature for 12 hours, the molar ratio of 6-bromo-2-naphthol, trifluoromethanesulfonate, pyridine and dichloromethane is 1: (1-2): (5-10): (10-30); track the entire reaction process with a TLC plate, transfer the reaction solution to a pear-shaped bottle after the reactants are completely reacted, and spin-dry the solvent; add ethyl acetate for dilution, extract, dry, concentrate, and then separate and purify by column chromatography to obtain compound N2:

[0013]

[0014] Step 2, synthesis of compound N3: Compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bis(diphenylphosphine) (BINAP) and cesium carbonate were weighed and placed in a two-necked flask with a condenser, the reaction device was sealed and connected to a double-row pipe system to evacuate nitrogen three times to ensure that the reaction system was in an anhydrous and oxygen-free environment, and then toluene and azetidine were injected respectively. The molar ratio of compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bis(diphenylphosphine) (BINAP), cesium carbonate, azetidine and toluene was 2.5:1. The reaction was observed to be 1: (0.1-0.3): (0.2-0.4): (1.5-3): (1.5-3): (30-50); the reaction was observed to be heated to 100°C in an oil bath and then stirred for 18 hours after the system refluxed. The reaction was carried out in a nitrogen atmosphere throughout the process. The TLC plate was used to track the entire reaction process. The reaction was terminated after the reactants were completely reacted. After the reaction solution naturally cooled to room temperature, it was transferred to a pear-shaped bottle and the solvent was dried by rotary evaporation. After dilution with dichloromethane, extraction, drying, concentration, and separation and purification by column chromatography were performed to obtain compound N3:

[0015]

[0016] Step 3, synthesizing compound N4: Compound N3, tetrakistriphenylphosphine palladium, and cuprous iodide are weighed separately and placed in a two-necked flask with a condenser, the reaction device is connected to a double-row pipe system and evacuated and replaced with nitrogen three times to ensure that the reaction system is in an anhydrous and oxygen-free environment, and diisopropylamine, toluene and trimethylsilylacetylene are injected into the two-necked flask in sequence, and the molar ratio of compound N3, tetrakistriphenylphosphine palladium, cuprous iodide, trimethylsilylacetylene, diisopropylamine and toluene is 1:(0.05-0.2):( 0.05~0.2):(1.5~2):(10~20):(30~50), the oil bath was heated to 100°C and the system was refluxed and then stirred for 12 hours. The whole reaction was carried out in a nitrogen atmosphere. The TLC plate was used to track the whole reaction. The reaction was terminated after the reactants were completely reacted. After the reaction solution naturally reached room temperature, it was transferred to a pear-shaped bottle and the solvent was dried by spin drying. After dilution with dichloromethane, it was extracted, dried, concentrated, and separated and purified by column chromatography to obtain compound N4:

[0017]

[0018] Step 4, synthesis of compound N5: weigh compound N4 and place it in a round-bottom flask, dissolve it in anhydrous tetrahydrofuran, then inject 1 mol / L tetrabutylammonium fluoride tetrahydrofuran solution, the molar ratio of compound N4, tetrabutylammonium fluoride and tetrahydrofuran is 1: (5-10): (30-50), stir at room temperature for 4 hours, track the whole reaction process with a TLC plate, terminate the reaction after the reactants are completely reacted, dilute with dichloromethane, extract, dry, concentrate, and then separate and purify by column chromatography to obtain compound N5:

[0019]

[0020] Step 5, synthesis of compound 2: 4-bromo-1,8-naphthalene dicarboxylic anhydride was weighed and placed in a two-necked flask with a condenser, anhydrous ethanol and N-Boc-diaminoalkane were added in sequence, the molar ratio of 4-Br-1,8-naphthalene dicarboxylic anhydride, N-Boc-diaminoalkane and anhydrous ethanol was 1:(1.5-2):(30-50), the oil bath was heated to 100°C, the system was refluxed and stirred for 12 hours; the whole reaction process was tracked by TLC plate, the reaction was terminated after the reactants were completely reacted, and the mixture was naturally cooled to room temperature and then filtered, washed, and the filter cake was collected and transferred to a pear-shaped bottle for rotary evaporation to remove residual dichloromethane and ethanol solvent to obtain compound 2:

[0021]

[0022] In the above formula, n is 1 or 2 or 3 or 4.

[0023] Step 6, synthesizing compound NADCA: weigh compound 2, compound N5, tetrakistriphenylphosphine palladium, and cuprous iodide respectively and place them in a two-necked flask, connect the reaction device to a double-row pipe system to evacuate and replace nitrogen three times, inject toluene and triethylamine into the reaction flask respectively, the molar ratio of compound N5, compound 2, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine and toluene is 1: (1.2-1.5): (0.1-0.2): (0.1-0.3): (10-20): (30-50), heat the oil bath to 100°C, reflux the system and continue stirring for 12 hours, and the reaction is carried out in a nitrogen atmosphere throughout the process; track the reaction with a TLC plate, terminate the reaction after the reactants are completely reacted, transfer the reaction solution to a pear-shaped flask after naturally cooling to room temperature, and spin-dry the solvent; dilute with dichloromethane, extract, dry, concentrate, and then separate and purify by column chromatography to obtain compound NADCA.

[0024] As a preferred solution of the present invention, the flexible fluorescent sensor film is prepared as follows:

[0025] Step 7, weigh the fluorescent compound NADCA and cellulose triacetate (CTA), respectively, dissolve them in a mixed solvent of dimethyl sulfoxide and dichloromethane, stir at room temperature, and obtain CTA@NADCA spinning solutions with different mass fractions after standing / ultrasonic degassing.

[0026] Step 8, using JDF 05 electrospinning instrument, extract CTA@NADCA spinning solution with a syringe and fix it on the syringe pump; adjust the distance between the needle and the receiver, select the receiving roller as the receiving device, and wrap a layer of release paper on the receiving roller. Close the spinning box door, set the origin of the needle movement and adjust the spinning parameters, then start the electrospinning machine, and collect for 4 hours at room temperature; after the collection is completed, turn off the power, remove the release paper, put it in a vacuum oven at 40°C and dry it for more than 2 hours to remove the solvent, and finally place the prepared film in a dark and dry place for use.

[0027] As a preferred embodiment of the present invention, in step 1, the extraction is performed sequentially using 5% hydrochloric acid aqueous solution, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution; the drying is performed using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is performed using petroleum ether as an eluent for column separation;

[0028] In the step 2, the extraction is performed by distilled water and saturated sodium chloride solution in sequence; the drying is performed by drying with anhydrous sodium sulfate for 2 hours; the column chromatography separation and purification is performed by using a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of (15-30):1 as an eluent for column separation;

[0029] In the step 3, the extraction is carried out using saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence; the drying is carried out using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is carried out using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of (6 to 10):1 as an eluent for column separation.

[0030] As a preferred embodiment of the present invention, in step 4, the extraction is performed using a saturated sodium bicarbonate solution and a saturated sodium chloride solution in sequence; the drying is performed using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is performed using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of (6 to 10):1 as an eluent for column separation.

[0031] As a preferred embodiment of the present invention, in step 5, the washing is performed 6 to 7 times with ethanol and dichloromethane. The N-Boc-diaminoalkane is any one of N-Boc-1,2-diaminoethane, N-Boc-1,4-diaminobutane, N-Boc-1,6-diaminohexane and N-Boc-1,8-diaminooctane.

[0032] As a preferred embodiment of the present invention, in step 6, the extraction is performed using saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence; the drying is performed using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is performed using a mixed solvent of dichloromethane and ethyl acetate in a volume ratio of (10-20):1 as an eluent for column separation.

[0033] As a preferred embodiment of the present invention, in step 7, the stirring time is 12 h to 20 h.

[0034] As a preferred embodiment of the present invention, in step 8, the extraction volume is 6ml~8mL; the receiving distance is (10cm~15cm); the spinning parameters are: the drum speed is 300r / min, the spinning voltage is (14kV~20kV), the needle reciprocating movement distance is (80mm~100mm), and the syringe thrust speed is (0.6mL / h~1.0mL / h).

[0035] As a preferred embodiment of the present invention, a flexible fluorescent sensor film obtained by a preparation method of a flexible fluorescent sensor film based on a fluorescent probe is used in the detection of peroxide explosives, wherein the explosive is triacetone triperoxide (TATP).

[0036] Compared with the prior art: The present invention is a method for preparing a flexible fluorescent sensor film based on a fluorescent probe. The 1,8-naphthalene imide derivative has the characteristics of large Stokes shift, good photochemical stability, easy modification, sensitivity to the microenvironment, and rich fluorescent output signals. It is an ideal sensing unit for preparing fluorescent sensor films. We connected naphthylacetylene with azetidine at one end to the 4th position of 1,8-naphthalene imide, designed and synthesized a D-π-A type fluorescent molecular probe (NADCA). The study of photophysical properties showed that the fluorescent compound showed strong sensitivity to the polarity of the environment. Subsequently, the film was prepared by electrospinning technology, and the photophysical properties of the film were systematically tested. In addition, the film CTA@NADCA can achieve rapid (<1s), sensitive (detection limit as low as 10.9ppb), and highly selective response to trace acetone vapor, and can be reused many times. Since acetone is the main decomposition product of peroxide explosive TATP, we investigated the sensing behavior of the film to trace amounts of TATP. The results showed that the prepared film CTA@NADCA can be used for on-site detection of the explosive TATP. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 This is a UV-visible absorption spectrum of a fluorescent probe based on 1,8-naphthalimide derivatives prepared in Example 1 of the present invention;

[0039] Figure 2 This is a fluorescence spectrum of a fluorescent probe based on 1,8-naphthalimide derivatives prepared in Example 1 of the present invention;

[0040] Figure 3 is a sensitivity experimental spectrum diagram of the flexible fluorescent film prepared in Example 1 of the present invention to acetone vapor;

[0041] Figure 4 This is a repeatability experimental spectrum diagram of the flexible fluorescent film prepared in Example 1 of the present invention to acetone vapor;

[0042] Figure 5 This is an experimental spectrum diagram of the anti-interference performance of the flexible fluorescent film prepared in Example 1 of the present invention to acetone vapor;

[0043] Figure 6 This is a spectrum diagram of the sensitivity experiment of the flexible fluorescent film prepared in Example 1 of the present invention to TATP. DETAILED DESCRIPTION

[0044] The flexible fluorescent sensor film obtained by the preparation method of the flexible fluorescent sensor film based on a fluorescent probe of the present invention has high sensitivity, good selectivity and rapid response; the synthesis method of the fluorescent probe and the preparation method of the film are simple to operate, have low requirements on equipment, and are suitable for scaled-up production; the fluorescent film can be widely used in the detection of TATP.

[0045] The present invention is achieved through the following technical solutions:

[0046] First, the synthesis of 1,8-naphthalimide derivative fluorescent probe was carried out. The structural formula of the fluorescent probe is as follows:

[0047]

[0048] Wherein, n is 1 or 2 or 3 or 4. The specific synthesis route is as follows:

[0049]

[0050] The method for synthesizing the 1,8-naphthalimide derivative fluorescent probe of the present invention comprises the following steps:

[0051] Step 1, synthesizing compound N2;

[0052] Weigh 6-Br-2-naphthol and place it in a 100mL round-bottom flask, add redistilled dichloromethane (25mL) and anhydrous pyridine (3.6mL), add trifluoromethanesulfonate dropwise to the reaction solution under ice bath conditions, the molar ratio of 6-bromo-2-naphthol, trifluoromethanesulfonate, pyridine and dichloromethane used in the reaction is 1: (1-2): (5-10): (10-30), and stir at room temperature for 12h. Track the entire reaction process through TLC plates, and after the reactants are completely reacted, transfer the reaction solution to a pear-shaped bottle and spin dry the solvent. Add ethyl acetate (200mL) for dilution, then extract with 5% hydrochloric acid aqueous solution, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution in sequence, collect the organic phase and dry it with anhydrous sodium sulfate for 2h, and after drying, use a sand core funnel for suction filtration, collect the filtrate, concentrate it, and separate it by column chromatography (eluent: petroleum ether) to obtain compound N2:

[0053]

[0054] Step 2, synthesizing compound N3;

[0055] Compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bisdiphenylphosphine (BINAP) and cesium carbonate were weighed and placed in a 250 mL two-necked flask with a condenser. The reaction device was sealed and connected to a double-row pipe system to evacuate nitrogen three times to ensure that the reaction system was in an anhydrous and oxygen-free environment. Toluene and azetidine were then injected respectively. The molar ratio of compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bisdiphenylphosphine (BINAP), cesium carbonate, azetidine and toluene used in the reaction was 1: (0.1-0.3): (0.2-0.4): (1.5-3): (1.5-3): (30-50). The reaction was observed to be heated to 100°C in an oil bath and then stirred for 18 hours after reflux. The reaction was carried out in a nitrogen atmosphere throughout. The whole process of the reaction was tracked by TLC plate. The reaction was terminated after the reactants were completely reacted. After the temperature naturally dropped to room temperature, the reaction solution was transferred to a pear-shaped bottle and the solvent was dried by spin drying. After dilution with dichloromethane (100 mL), it was extracted with distilled water and saturated sodium chloride solution in turn. The organic phase was dried with anhydrous sodium sulfate for 2 h. After drying, it was filtered using a sand core funnel. The filtrate was collected and concentrated, and then separated by column chromatography (eluent: petroleum ether: ethyl acetate = 15-30:1) to obtain compound N3:

[0056]

[0057] Step 3, synthesizing compound N4;

[0058] Weigh compound N3, tetrakistriphenylphosphine palladium, and cuprous iodide respectively and place them in a 100mL two-necked flask with a condenser. Connect the reaction device to a double-row pipe system and evacuate and replace nitrogen three times to ensure that the reaction system is in an anhydrous and oxygen-free environment. Inject 10mL of diisopropylamine, 25mL of toluene, and trimethylsilylacetylene into the two-necked flask in turn. The molar ratio of compound N3, tetrakistriphenylphosphine palladium, cuprous iodide and trimethylsilylacetylene, diisopropylamine and toluene used in the reaction is 1: (0.05-0.2): (0.05-0.2): (1.5-2): (10-20): (30-50). After the oil bath is heated to 100°C and the system refluxes, stirring is continued for 12 hours. The reaction is carried out in a nitrogen atmosphere throughout the process. TLC plates are used to track the entire reaction process. The reaction is terminated after the reactants are completely reacted. After naturally reaching room temperature, the reaction solution is transferred to a pear-shaped flask and the solvent is dried. After dilution with dichloromethane (100 mL), the mixture was extracted with saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence. The organic phase was dried with anhydrous sodium sulfate for 2 h, and then filtered using a sand core funnel. The filtrate was collected and concentrated, and then separated by column chromatography (eluent: petroleum ether: dichloromethane = 6-10:1) to obtain compound N4:

[0059]

[0060] Step 4, synthesizing compound N5;

[0061] A certain amount of compound N4 was weighed and placed in a 50 mL round-bottom flask, dissolved in anhydrous tetrahydrofuran (15 mL), and then injected with a 1 mol / L tetrabutylammonium fluoride tetrahydrofuran solution (5 mL), the molar ratio of compound N4, tetrabutylammonium fluoride and tetrahydrofuran was 1: (5-10): (30-50), stirred at room temperature for 4 h, and the whole reaction process was tracked by TLC plate. After the reactants were completely reacted, the reaction was terminated, diluted with dichloromethane, and then extracted with saturated sodium bicarbonate solution and saturated sodium chloride solution in sequence, the organic phase was dried with anhydrous sodium sulfate for 2 h, and after drying, it was filtered using a sand core funnel, the filtrate was collected and concentrated, and then separated by column chromatography (eluent: petroleum ether: dichloromethane = 6-10: 1) to obtain compound N5:

[0062]

[0063] Step 5, synthesizing compound 2;

[0064] Weigh 4-Br-1,8-naphthalene dicarboxylic anhydride and place it in a 100mL two-necked flask with a condenser, and add anhydrous ethanol and N-Boc-diaminoalkane in sequence. The molar ratio of 4-Br-1,8-naphthalene dicarboxylic anhydride, N-Boc-diaminoalkane and anhydrous ethanol used in the reaction is 1:(1.5-2):(30-50). Heat the oil bath to 100°C and stir for 12 hours after the system refluxes. Track the entire reaction on a TLC plate. After the reactants have reacted completely, terminate the reaction. After naturally cooling to room temperature, filter and wash impurities with ethanol and dichloromethane, respectively. Collect the filter cake and transfer it to a pear-shaped bottle and evaporate it to remove the residual dichloromethane and ethanol solvents to obtain compound 2:

[0065]

[0066] The N-Boc-diaminoalkane is any one of N-Boc-1,2-diaminoethane, N-Boc-1,4-diaminobutane, N-Boc-1,6-diaminohexane and N-Boc-1,8-diaminooctane.

[0067] Step 6, synthesizing compound NADCA;

[0068] Compound N5, compound 2, tetrakistriphenylphosphine palladium and cuprous iodide were weighed and placed in a 25 mL two-necked flask at a molar ratio of 1: (1.2-1.5): (0.1-0.2): (0.1-0.3). The reaction apparatus was connected to a double-row pipe system and evacuated for nitrogen three times. Toluene and triethylamine were injected into the reaction flask respectively. The molar ratio of compound N5, compound 2, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine and toluene was 1: (1.2-1.5): (0.1-0.2): (0.1-0.3): (10-20): (30-50). The oil bath was heated to 100°C and the system was refluxed and stirred for 12 hours. The reaction was carried out in a nitrogen atmosphere throughout. After dilution with dichloromethane (50 mL), the mixture was extracted with saturated ammonium chloride solution, saturated sodium bicarbonate solution and saturated sodium chloride solution in sequence. The organic phase was dried over anhydrous sodium sulfate for 2 h. After drying, it was filtered using a sand core funnel. The filtrate was collected and concentrated, and then separated by column chromatography (eluent: dichloromethane: ethyl acetate = 10-20:1) to obtain the compound NADCA.

[0069] The method for preparing a flexible fluorescent sensor film comprises the following steps:

[0070] Step 7, preparation of spinning solution;

[0071] A mixed solution of dimethyl sulfoxide (DMSO) and dichloromethane (DCM) of fluorescent probe NADCA and cellulose triacetate (CTA) was prepared, wherein the mass ratio of NADCA, CTA, DMSO and DCM was 1: (300-400): (2000-2500): (700-800), and the mixture was stirred on a normal temperature stirrer for 12-20 hours. After standing / ultrasonic degassing, CTA@NADCA spinning solutions with different mass fractions were obtained.

[0072] Step 8, preparation of thin film;

[0073] Using the JDF 05 electrospinning instrument, 6-8 mL CTA@NADCA spinning solution was extracted with a 10 mL syringe and fixed on the injection pump. The spinneret needle used a 20G needle, and the distance between the needle and the receiver was adjusted to 10-15 cm. The receiving roller was selected as the receiving device, and a layer of release paper was applied to the receiving roller. Then the spinning box door was closed, the origin of the needle movement was set, and the spinning parameters were adjusted (the roller speed was 300 r / min, the spinning voltage was 14-20 kV, the needle reciprocating distance was 80-100 mm, and the syringe propulsion speed was 0.6-1.0 mL / h), and then the electrospinning machine was started and collected for 4 hours at room temperature and 45% humidity. After the collection was completed, the power was turned off and the release paper was carefully removed, and it was placed in a vacuum oven at 40 ° C for more than 2 hours to remove the solvent, and then collected and placed in a dark and dry place for later use.

[0074] The use of the electrospun film based on the 1,8-naphthalimide derivative fluorescent probe in detecting peroxide explosives, wherein the peroxide explosive is triacetone triperoxide (TATP), and the detection method is as follows:

[0075] 1. Preparation of TATP

[0076] Under ice bath conditions, add 0.2mL (2.7mmol) acetone to a 5mL test tube, add 0.348mL (3.375mmol) 30% hydrogen peroxide under magnetic stirring, then drop 0.225mL (2.7mmol) 37% concentrated hydrochloric acid under ice bath conditions, white flocculent precipitates appear in the test tube, keep ice bath and stir for 1h, then naturally warm to room temperature, continue stirring for 24h. After the reaction is completed, collect the filter cake after multiple washings and filtration, dry naturally at room temperature, then use a non-metallic medicine spoon to transfer TATP to a sample bottle and seal it in a refrigerator at 2-8℃ for use. All utensils used in the reaction, filtration and transfer process are washed with 5% hydrochloric acid aqueous solution to decompose the residual TATP.

[0077] 2. Detection of samples to be tested

[0078] We put different masses of TATP powder into multiple glass sample bottles with a volume of 500mL, and sealed them to prevent leakage. Then the sample bottle was sealed and placed in a light-proof dry place for 24h. The gas above the solid in the bottle was considered to be the saturated vapor of acetone and hydrogen peroxide volatilized by the decomposition of TATP. In order to carry out the sensing test, the FS5 fluorescence instrument was used for fluorescence characterization. The fluorescent film was cut into a suitable size and placed in a special four-way cuvette. The silicone sealing cover with a pinhole was assembled. A 20mL syringe equipped with a metal needle was used to extract the gas from the headspace of the sealed sample bottle, and then injected into the cuvette, and the gas to be tested was blown directly on the surface of the fluorescent film. After stabilization for a period of time, the fluorescence test was carried out. In order to ensure the accuracy and repeatability of the detection, the temperature, humidity and atmospheric pressure of the test environment were recorded in real time during the test, and the sensing test of each gas to be tested was repeated at least five times.

[0079] The electrospun film of the present invention based on the 1,8-naphthalimide derivative fluorescent probe has good chemical stability, fast response speed, good selectivity, can be directly detected, and can achieve efficient detection of TATP using FS5, a portable ultraviolet lamp or other similar optical detectors.

[0080] Example 1

[0081] The present invention provides a method for preparing a flexible fluorescent sensor film based on a fluorescent probe.

[0082] First, a 1,8-naphthalimide derivative fluorescent probe with the following structural formula was synthesized:

[0083]

[0084] Its synthesis method comprises the following steps:

[0085] Step 1, synthesizing compound N2;

[0086] Weigh 6-Br-2-naphthol and place it in a 100mL round-bottom flask, add redistilled dichloromethane (25mL) and anhydrous pyridine (3.6mL), add trifluoromethanesulfonate dropwise to the reaction solution under ice bath conditions, the molar ratio of 6-bromo-2-naphthol, trifluoromethanesulfonate, pyridine and dichloromethane used in the reaction is 1:1:5:10, and stir at room temperature for 12h. Track the entire reaction process through TLC plates, and after the reactants are completely reacted, transfer the reaction solution to a pear-shaped bottle and spin dry the solvent. Add ethyl acetate (200mL) for dilution, then extract with 5% hydrochloric acid aqueous solution, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution in sequence, collect the organic phase and dry it with anhydrous sodium sulfate for 2h, and after drying, use a sand core funnel for suction filtration, collect the filtrate, concentrate it, and separate it by column chromatography (eluent: petroleum ether) to obtain compound N2:

[0087]

[0088] Step 2, synthesizing compound N3;

[0089] Compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bisdiphenylphosphine (BINAP) and cesium carbonate were weighed and placed in a 250 mL two-necked flask with a condenser. The reaction device was sealed and connected to a double-row pipe system to evacuate nitrogen three times to ensure that the reaction system was in an anhydrous and oxygen-free environment. Toluene and azetidine were then injected respectively. The molar ratio of compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bisdiphenylphosphine (BINAP), cesium carbonate, azetidine and toluene used in the reaction was 1:0.1:0.2:1.5:1.5:30. The reaction was observed to be heated to 100°C in an oil bath and then stirred for 18 hours after the system refluxed. The reaction was carried out in a nitrogen atmosphere throughout the process. The TLC plate tracked the entire reaction process. The reaction was terminated after the reactants were completely reacted. After naturally cooling to room temperature, the reaction solution was transferred to a pear-shaped bottle and the solvent was dried. After dilution with dichloromethane (100 mL), the mixture was extracted with distilled water and saturated sodium chloride solution in sequence. The organic phase was dried with anhydrous sodium sulfate for 2 h. After drying, the mixture was filtered using a sand core funnel. The filtrate was collected and concentrated, and then separated by column chromatography (eluent: petroleum ether: ethyl acetate = 15:1) to obtain compound N3:

[0090]

[0091] Step 3, synthesizing compound N4;

[0092] Weigh compound N3, tetrakistriphenylphosphine palladium, and cuprous iodide respectively and place them in a 100mL two-necked flask with a condenser. Connect the reaction device to a double-row pipe system and evacuate nitrogen three times to ensure that the reaction system is in an anhydrous and oxygen-free environment. Inject 10mL of diisopropylamine, 25mL of toluene, and trimethylsilylacetylene into the two-necked flask in turn. The molar ratio of compound N3, tetrakistriphenylphosphine palladium, cuprous iodide, trimethylsilylacetylene, diisopropylamine, and toluene used in the reaction is 1:0.05:0.05:1.5:10:30. After the oil bath is heated to 100°C and the system refluxes, stirring is continued for 12 hours. The reaction is carried out in a nitrogen atmosphere throughout the process. TLC plates track the entire reaction process. The reaction is terminated after the reactants are completely reacted. After naturally reaching room temperature, the reaction solution is transferred to a pear-shaped flask and the solvent is dried. After dilution with dichloromethane (100 mL), the mixture was extracted with saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence. The organic phase was dried with anhydrous sodium sulfate for 2 h, and then filtered using a sand core funnel. The filtrate was collected, concentrated, and separated by column chromatography (eluent: petroleum ether: dichloromethane = 6:1) to obtain compound N4:

[0093]

[0094] Step 4, synthesizing compound N5;

[0095] A certain amount of compound N4 was weighed and placed in a 50 mL round-bottom flask, dissolved in anhydrous tetrahydrofuran (15 mL), and then injected with a 1 mol / L tetrabutylammonium fluoride tetrahydrofuran solution (5 mL), the molar ratio of compound N4, tetrabutylammonium fluoride and tetrahydrofuran was 1:5:30; stirred at room temperature for 4 h, and the whole reaction process was tracked by TLC plate. After the reactants were completely reacted, the reaction was terminated, diluted with dichloromethane, and then extracted with saturated sodium bicarbonate solution and saturated sodium chloride solution in sequence, the organic phase was dried with anhydrous sodium sulfate for 2 h, and after drying, it was filtered using a sand core funnel, the filtrate was collected and concentrated, and then separated by column chromatography (eluent: petroleum ether: dichloromethane = 6:1) to obtain compound N5:

[0096]

[0097] Step 5, synthesizing compound 2;

[0098] Weigh 4-Br-1,8-naphthalene dicarboxylic anhydride and place it in a 100mL two-necked flask with a condenser, and add anhydrous ethanol and N-Boc-diaminoalkane in sequence. The molar ratio of 4-Br-1,8-naphthalene dicarboxylic anhydride, N-Boc-diaminoalkane and anhydrous ethanol used in the reaction is 1:1.5:30. Heat the oil bath to 100°C and stir for 12 hours after the system refluxes. Track the entire reaction on a TLC plate. After the reactants have reacted completely, terminate the reaction. After naturally cooling to room temperature, filter and wash impurities with ethanol and dichloromethane, respectively. Collect the filter cake and transfer it to a pear-shaped bottle for rotary evaporation to remove the residual dichloromethane and ethanol solvents to obtain compound 2:

[0099]

[0100] Step 6, synthesizing NADCA;

[0101] Compound N5, compound 2, tetrakistriphenylphosphine palladium, and cuprous iodide were weighed and placed in a 25 mL two-necked flask at a molar ratio of 1:1.2:0.1:0.1, and the reaction device was connected to a double-row pipe system for three times of evacuation and nitrogen exchange. Toluene and triethylamine were injected into the reaction flask respectively. The molar ratio of compound N5, compound 2, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine and toluene was 1:1.2:0.1:0.1:10:30. The oil bath was heated to 100°C and the system was refluxed and stirred for 12 hours. The reaction was carried out in a nitrogen atmosphere throughout. After dilution with dichloromethane (50 mL), it was extracted with saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence. The organic phase was dried with anhydrous sodium sulfate for 2 hours, and after drying, it was filtered using a sand core funnel. The filtrate was collected and concentrated, and then separated by column chromatography (eluent: dichloromethane: ethyl acetate = 10:1) to obtain compound NADCA:

[0102]

[0103] The above NMR data of the fluorescent probe NADCA based on 1,8-naphthalimide derivatives are: 1 H NMR(400MHz,Chloroform-d)δ8.80(t,J=6.4Hz,1H),8.63(d,J=6.3Hz,1H),8.55(t,J=6.6Hz,1H),8.04(d, J=4.9Hz,1H),7.95(t,J=6.6Hz,1H),7.84(q,J=7.1Hz,1H),7.71(t,J=6.7Hz,1H),7.64(t,J=6.6Hz,1H),7. 57(t,J=6.7Hz,1H),6.83(t,J=6.6Hz,1H),6.64(s,1H),4.17(q,J=6.9Hz,2H),4.04(q,J=6.8Hz,4H),3.23– 2.99(m,2H),2.45(h,J=7.3,6.9Hz,2H),1.80–1.69(m,2H),1.44(d,J=4.9Hz,12H),0.85(d,J=22.3Hz,2H).

[0104] Step 7, preparation of spinning solution;

[0105] A mixed solution of dimethyl sulfoxide (DMSO) and dichloromethane (DCM) of fluorescent probe NADCA and cellulose triacetate (CTA) was prepared, wherein the mass ratio of NADCA, CTA, DMSO and DCM was 1: (300-400): (2000-2500): (700-800), and the mixture was stirred on a normal temperature stirrer for 12-20 hours. After standing / ultrasonic degassing, CTA@NADCA spinning solutions with different mass fractions were obtained.

[0106] Step 8, preparation of thin film;

[0107] Using the JDF 05 electrospinning instrument, 6-8 mL CTA@NADCA spinning solution was extracted with a 10 mL syringe and fixed on the injection pump. The spinneret needle used a 20G needle, and the distance between the needle and the receiver was adjusted to 10-15 cm. The receiving roller was selected as the receiving device, and a layer of release paper was applied to the receiving roller. Then the spinning box door was closed, the origin of the needle movement was set, and the spinning parameters (spinning voltage 14-20 kV, needle reciprocating distance 40-100 mm, syringe propulsion speed 0.4-1.0 mL / h) were adjusted, and the electrospinning machine was started, and the samples were collected for 4 hours at room temperature and 45% humidity. After the collection was completed, the power was turned off and the release paper was carefully removed, and it was placed in a vacuum oven for drying for more than 2 hours to remove the solvent, and then collected and placed in a dark and dry place for use.

[0108] The photophysical properties of the synthesized fluorescent probe based on 1,8-naphthalimide derivatives were tested. The specific method is as follows:

[0109] (1) Prepare the solution.

[0110] The basic photophysical properties of NADCA in homogeneous phase were tested, and its UV / visible absorption spectra and fluorescence spectra in different solvents and different concentrations in the same solvent were tested. First, prepare the mother solution, weigh 1 mg of NADCA powder, put it in a 5 mL sample bottle, use a pipette to take 1.7 mL of good solvent dichloromethane to dissolve it, and prepare 1×10 -3 The stock solution of M was diluted as needed in subsequent experiments.

[0111] (2) UV-visible absorption spectrum test.

[0112] First, we investigated the effect of the compound at a concentration of 1×10 -5 UV-visible absorption spectra of M in different types of solvents. The results are as follows Figure 1 As shown in Figure a, it was found that the shape of the absorption spectrum of the compound in different solvents and the position of the strongest absorption peak did not show regular changes, indicating that the absorption properties of the compound were little affected by the polarity or structure of the solvent. Subsequently, its UV-visible absorption spectrum in 1,4-dioxane solutions of different concentrations was tested, as shown in Figure 5. Figure 1 As shown in Figure b, the absorption spectrum of NADCA is mainly distributed in the two bands of 280-340nm and 390-520nm, and the positions of its strongest absorption peaks are 330 and 440nm, corresponding to the electronic transition processes of π→π* and n→π*, respectively.

[0113] (3) Fluorescence spectrum test.

[0114] In order to investigate the fluorescence properties of NADCA in solution, we tested its fluorescence spectra in different solvent systems and in the same solvent system as the concentration changes, using 440nm as the excitation light. Figure 2 As shown in Figure a, as the polarity of the solvent increases, the fluorescence emission wavelength of NADCA undergoes a large red shift (500nm~603nm), proving that NADCA is very sensitive to changes in solvent polarity and will have a large fluorescence change with a slight change in polarity. Figure 2 As shown in Figure b, the fluorescence intensity of NADCA in 1,4-dioxane solvent changes with the solution concentration. Initially, the fluorescence intensity of compound NADCA gradually increases with the increase of solution concentration. When the concentration is 2×10 -5 M, and then its fluorescence intensity gradually weakened as the concentration continued to increase, proving the existence of aggregation-induced fluorescence quenching (ACQ) phenomenon.

[0115] The use of the electrospun film based on the 1,8-naphthalimide derivative fluorescent probe in detecting peroxide explosives, wherein the peroxide explosive is triacetone triperoxide (TATP), and the detection method is as follows:

[0116] (1) Preparation of TATP

[0117] Under ice bath conditions, add 0.2mL (2.7mmol) acetone to a 5mL test tube, add 0.348mL (3.375mmol) 30% hydrogen peroxide under magnetic stirring, then drop 0.225mL (2.7mmol) 37% concentrated hydrochloric acid under ice bath conditions, white flocculent precipitates appear in the test tube, keep ice bath and stir for 1h, then naturally warm to room temperature, continue stirring for 24h. After the reaction is completed, collect the filter cake after multiple washings and filtration, dry naturally at room temperature, then use a non-metallic medicine spoon to transfer TATP to a sample bottle and seal it in a refrigerator at 2-8℃ for use. All utensils used in the reaction, filtration and transfer process are washed with 5% hydrochloric acid aqueous solution to decompose the residual TATP.

[0118] (2) Detection of samples to be tested

[0119] In the study of the photophysical properties of NADCA, we detected different types of volatile organic gases and found that the prepared CTA@NADCA film had an obvious quenching response in acetone vapor. Since acetone is a decomposition product of the peroxide explosive TATP, we first examined the response of the film to acetone vapor and performed fluorescence sensing tests on the FS5 fluorescence instrument.

[0120] First, place the same mass of acetone in 10 glass sample bottles with a volume gradient of 20 to 500 mL, seal them with rubber stoppers to prevent gas leakage, and then place the sample bottles in a light-proof and dry place for 24 hours. Under this condition, the gas above the liquid in the bottle is considered to be its saturated vapor. Place the fluorescent film in a cuvette and inject different concentrations of acetone gas with a syringe. After stabilization for a period of time, perform a fluorescence test. In order to ensure the accuracy and repeatability of the test, the temperature, humidity and atmospheric pressure of the test environment are recorded in real time during the test, and the test of different concentrations of acetone gas is repeated at least five times.

[0121] The detection limit of acetone gas by the film is tested, such as Figure 3 As shown in the figure, when the concentration of acetone gas is 27ppb, the film still shows fluorescence quenching phenomenon, and as the concentration increases, it shows a more obvious quenching effect. In the concentration range of 27ppb to 3.4ppm, the fluorescence intensity of CTA@NADCA nanofiber membrane and acetone gas concentration show a good linear correlation. When the concentration increases to 221ppm, the film fluorescence is completely quenched. According to the test results, the theoretical detection limit of CTA@NADCA film for acetone gas DL = 10.9ppb can be calculated.

[0122] Repeatability test of film for acetone gas detection, such as Figure 4 As shown in the figure, we conducted more than ten detection / recovery cycle tests on the prepared CTA@NADCA fluorescent film, and recorded the data of the first ten times. It can be seen that the response of the CTA@NADCA film to acetone gas is almost instantaneous and completely quenched, and the sensing process is completely reversible. The fluorescence intensity can basically be completely restored to the initial value after each detection. After ten cycle tests, the fluorescence intensity of the film showed no obvious signs of attenuation, indicating that the film has excellent repeatability and meets the requirements of long-term use.

[0123] The film was used for the selectivity test of acetone gas detection. 18 possible interferences were selected for detection. The detection concentration of different gases was 300ppm. TATP was also tested. The results are as follows: Figure 5 As shown in the figure, it can be seen that the CTA@NADCA nanofiber film we prepared can achieve selective testing of acetone gas in practical applications. In addition, the film also shows a relatively sensitive response to TATP, with a quenching efficiency of about 51% and a quenching efficiency of 99% for acetone, indicating that the fluorescent film can achieve highly selective detection of trace amounts of TATP in the environment.

[0124] Through a systematic study of the sensing behavior of the prepared fluorescent film, it is shown that the CTA@NADCA film can achieve rapid, sensitive, repeatable and highly selective detection of acetone gas, and can be extended to the on-site detection of peroxide explosives TATP. In order to further determine the sensitivity of the film to TATP detection, we synthesized a trace amount of TATP and placed different masses of TATP in glassware of the same volume, kept it in a dark place for 24 hours to decompose it, and then conducted a sensitivity test. The results are as follows: Figure 6 As shown, it can at least achieve sensitive detection of more than 8 μg of TATP in the environment.

[0125] In summary, the electrospun nanofiber membrane based on 1,8-naphthalimide derivatives of the present invention has good photochemical stability and strong fluorescence quantum efficiency, can achieve highly selective and sensitive response to trace amounts of acetone gas and peroxide explosives TATP, and can be reused.

[0126] Example 2

[0127] The method for preparing a flexible fluorescent sensing film based on a fluorescent probe of the present invention is different from that of Example 1 in that the fluorescent probe based on a 1,8-naphthalimide derivative having the following synthetic structural formula is:

[0128]

[0129] The synthesis method steps are as follows:

[0130] In step 5 of the synthesis of 1,8-naphthaleneimide derivatives in Example 1, the N-Boc-diaminohexane used was replaced with N-Boc-1,2-diaminoethane of equal molar mass, and the other steps were the same as those in the corresponding Example 1.

[0131] Example 3

[0132] The method for preparing a flexible fluorescent sensing film based on a fluorescent probe of the present invention is different from that of Example 1 in that the fluorescent probe based on a 1,8-naphthalimide derivative having the following synthetic structural formula is:

[0133]

[0134] In step 5 of the synthesis of 1,8-naphthaleneimide derivatives in Example 1, the N-Boc-diaminohexane used was replaced with N-Boc-1,4-diaminobutane of equal molar mass, and the other steps were the same as those in the corresponding Example 1.

[0135] Example 4

[0136] The method for preparing a flexible fluorescent sensing film based on a fluorescent probe of the present invention is different from that of Example 1 in that the fluorescent probe based on a 1,8-naphthalimide derivative having the following synthetic structural formula is:

[0137]

[0138] In step 5 of the synthesis of 1,8-naphthaleneimide derivatives in Example 1, the N-Boc-diaminohexane used was replaced with N-Boc-1,8-diaminooctane of equal molar mass, and the other steps were the same as those in the corresponding Example 1.

Claims

1. A method for preparing a flexible fluorescent sensing film based on a fluorescent probe, characterized in that: The molecule of the fluorescent probe is based on a 1,8-naphthaleneimide derivative as a core unit, with azetidine-modified naphthylacetylene introduced at one end, and alkyl chains of different lengths are typed at the other end through a condensation reaction; the fluorescent probe is evenly mixed with triacetyl cellulose by a physical mixing method to prepare a spinning solution, and a flexible fluorescent sensing film is prepared by electrospinning technology; the structural formula of the fluorescent probe is as follows: In the structural formula, n is 1, 2, 3 or 4.

2. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 1, characterized in that: The synthesis of the fluorescent probe is specifically carried out according to the following steps: Step 1, synthesizing compound N2: weigh 6-bromo-2-naphthol and place it in a round-bottom flask, add redistilled dichloromethane and anhydrous pyridine, add trifluoromethanesulfonate dropwise to the reaction solution under ice bath conditions, and stir at room temperature for 12 hours, the molar ratio of 6-bromo-2-naphthol, trifluoromethanesulfonate, pyridine and dichloromethane is 1: (1-2): (5-10): (10-30); track the entire reaction process with a TLC plate, transfer the reaction solution to a pear-shaped bottle after the reactants are completely reacted, and spin-dry the solvent; add ethyl acetate for dilution, extract, dry, concentrate, and then separate and purify by column chromatography to obtain compound N2: Step 2, synthesis of compound N3: Compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bis(diphenylphosphine) (BINAP) and cesium carbonate were weighed and placed in a two-necked flask with a condenser, the reaction device was sealed and connected to a double-row pipe system to evacuate nitrogen three times to ensure that the reaction system was in an anhydrous and oxygen-free environment, and then toluene and azetidine were injected respectively. The molar ratio of compound N2, palladium acetate, 1,1′-binaphthyl-2,2′-bis(diphenylphosphine) (BINAP), cesium carbonate, azetidine and toluene was 2.5:

1. The reaction was observed to be 1: (0.1-0.3): (0.2-0.4): (1.5-3): (1.5-3): (30-50); the reaction was observed to be heated to 100°C in an oil bath and then stirred for 18 hours after the system refluxed. The reaction was carried out in a nitrogen atmosphere throughout the process. The TLC plate was used to track the entire reaction process. The reaction was terminated after the reactants were completely reacted. After the reaction solution naturally cooled to room temperature, it was transferred to a pear-shaped bottle and the solvent was dried by rotary evaporation. After dilution with dichloromethane, extraction, drying, concentration, and separation and purification by column chromatography were performed to obtain compound N3: Step 3, synthesizing compound N4: Compound N3, tetrakistriphenylphosphine palladium, and cuprous iodide are weighed separately and placed in a two-necked flask with a condenser, the reaction device is connected to a double-row pipe system and evacuated and replaced with nitrogen three times to ensure that the reaction system is in an anhydrous and oxygen-free environment, and diisopropylamine, toluene and trimethylsilylacetylene are injected into the two-necked flask in sequence, and the molar ratio of compound N3, tetrakistriphenylphosphine palladium, cuprous iodide, trimethylsilylacetylene, diisopropylamine and toluene is 1:(0.05-0.2):( 0.05~0.2):(1.5~2):(10~20):(30~50), the oil bath was heated to 100°C and the system was refluxed and then stirred for 12 hours. The whole reaction was carried out in a nitrogen atmosphere. The TLC plate was used to track the whole reaction. The reaction was terminated after the reactants were completely reacted. After the reaction solution naturally reached room temperature, it was transferred to a pear-shaped bottle and the solvent was dried by spin drying. After dilution with dichloromethane, it was extracted, dried, concentrated, and separated and purified by column chromatography to obtain compound N4: Step 4, synthesis of compound N5: weigh compound N4 and place it in a round-bottom flask, dissolve it in anhydrous tetrahydrofuran, then inject 1 mol / L tetrabutylammonium fluoride tetrahydrofuran solution, the molar ratio of compound N4, tetrabutylammonium fluoride and tetrahydrofuran is 1: (5-10): (30-50), stir at room temperature for 4 hours, track the whole reaction process with a TLC plate, terminate the reaction after the reactants are completely reacted, dilute with dichloromethane, extract, dry, concentrate, and then separate and purify by column chromatography to obtain compound N5: Step 5, synthesis of compound 2: 4-bromo-1,8-naphthalene dicarboxylic anhydride was weighed and placed in a two-necked flask with a condenser, anhydrous ethanol and N-Boc-diaminoalkane were added in sequence, the molar ratio of 4-Br-1,8-naphthalene dicarboxylic anhydride, N-Boc-diaminoalkane and anhydrous ethanol was 1:(1.5-2):(30-50), the oil bath was heated to 100°C, the system was refluxed and stirred for 12 hours; the whole reaction process was tracked by TLC plate, the reaction was terminated after the reactants were completely reacted, and the mixture was naturally cooled to room temperature and then filtered, washed, and the filter cake was collected and transferred to a pear-shaped bottle for rotary evaporation to remove residual dichloromethane and ethanol solvent to obtain compound 2: In the above formula, n is 1 or 2 or 3 or 4. Step 6, synthesizing compound NADCA: weigh compound 2, compound N5, tetrakistriphenylphosphine palladium, and cuprous iodide respectively and place them in a two-necked flask, connect the reaction device to a double-row pipe system to evacuate and replace nitrogen three times, inject toluene and triethylamine into the reaction flask respectively, the molar ratio of compound N5, compound 2, tetrakistriphenylphosphine palladium, cuprous iodide, triethylamine and toluene is 1: (1.2-1.5): (0.1-0.2): (0.1-0.3): (10-20): (30-50), heat the oil bath to 100°C, reflux the system and continue stirring for 12 hours, and the reaction is carried out in a nitrogen atmosphere throughout the process; track the reaction with a TLC plate throughout the process, terminate the reaction after the reactants are completely reacted, transfer the reaction solution to a pear-shaped flask after naturally reaching room temperature, and spin dry the solvent; After dilution with dichloromethane, extraction, drying, concentration and column chromatography separation and purification were performed to obtain the compound NADCA.

3. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 2, characterized in that: The preparation of the flexible fluorescent sensing film is specifically as follows: Step 7, weigh the fluorescent compound NADCA and cellulose triacetate (CTA), respectively, dissolve them in a mixed solvent of dimethyl sulfoxide and dichloromethane, stir at room temperature, and obtain CTA@NADCA spinning solutions with different mass fractions after standing / ultrasonic degassing. Step 8: Use JDF 05 electrospinning instrument, extract CTA@NADCA spinning solution with a syringe, and fix it on the syringe pump; adjust the distance between the needle and the receiver, select the receiving roller as the receiving device, and wrap a layer of release paper on the receiving roller. Close the spinning box door, set the origin of the needle movement, adjust the spinning parameters, and then start the electrospinning machine, and collect for 4 hours at room temperature; After the collection is completed, turn off the power, remove the release paper, put it into a vacuum oven and dry it at 40°C for more than 2 hours to remove the solvent. Finally, place the prepared film in a dark and dry place for use.

4. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 3, characterized in that: In the step 1, the extraction is performed using 5% hydrochloric acid aqueous solution, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution in sequence; the drying is performed using anhydrous sodium sulfate for 2 hours; the column chromatography separation and purification is performed using petroleum ether as an eluent for column separation; In the step 2, the extraction is performed by distilled water and saturated sodium chloride solution in sequence; the drying is performed by drying with anhydrous sodium sulfate for 2 hours; the column chromatography separation and purification is performed by using a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of (15-30):1 as an eluent for column separation; In the step 3, the extraction is carried out using saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence; the drying is carried out using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is carried out using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of (6 to 10):1 as an eluent for column separation.

5. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 4, characterized in that: In the step 4, the extraction is performed using a saturated sodium bicarbonate solution and a saturated sodium chloride solution in sequence; the drying is performed using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is performed using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of (6 to 10):1 as an eluent for column separation.

6. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 5, characterized in that: In the step 5, the washing is performed by washing with ethanol and dichloromethane for 6 to 7 times. The N-Boc-diaminoalkane is any one of N-Boc-1,2-diaminoethane, N-Boc-1,4-diaminobutane, N-Boc-1,6-diaminohexane and N-Boc-1,8-diaminooctane.

7. The method for preparing a flexible fluorescent sensing film based on a fluorescent probe according to claim 6, characterized in that: In step 6, the extraction is performed using saturated ammonium chloride solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution in sequence; the drying is performed using anhydrous sodium sulfate for 2 hours; and the column chromatography separation and purification is performed using a mixed solvent of dichloromethane and ethyl acetate in a volume ratio of (10-20):1 as an eluent for column separation.

8. The method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to claim 7, characterized in that: In step 7, the stirring time is 12 h to 20 h.

9. The method for preparing a flexible fluorescent sensing film based on a fluorescent probe according to claim 8, characterized in that: In step 8, the extraction volume is 6ml~8mL; the receiving distance is (10cm~15cm); the spinning parameters are: the drum speed is 300r / min, the spinning voltage is (14kV~20kV), the needle reciprocating movement distance is (80mm~100mm), and the syringe thrust speed is (0.6mL / h~1.0mL / h).

10. A flexible fluorescent sensor film obtained by the method for preparing a flexible fluorescent sensor film based on a fluorescent probe according to any one of claims 1 to 9, characterized in that: Application in the detection of peroxide explosives, the explosive is triacetone triperoxide (TATP).

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