Preparation method and application of high-selectivity chemical warfare agent fluorescent probe based on free radicals

Abstract

The invention discloses a preparation method and application of a high-selectivity chemical warfare agent fluorescent probe based on free radicals, and belongs to the field of fluorescent probe materials. The invention aims to solve the problem that the existing fluorescent probe is seriously interfered by protonic acid. The method comprises the following steps: 1, preparing CZ-DTE-C1; and 2, preparing a filter paper strip membrane by using CZ-DTE-Cl doped polyoxyethylene. The high-selectivity chemical warfare agent fluorescent probe based on the free radicals is used for detecting mustard gas, phosgene or sarin and has high selectivity. Compared with the traditional fluorescent probes, such as an organic metal compound probe, a nitrogen-oxygen bifunctional nucleophilic reagent probe, a nitrogen-based nucleophilic reagent probe and an oxygen-based nucleophilic reagent probe, the fluorescent probe provided by the invention is a novel free radical-based sensing reaction, and can simultaneously realize visual-fluorescent dual-mode detection of mustard gas, phosgene and sarin simulants; the selectivity is high.

Description

Technical Field

[0001] The present invention belongs to the field of fluorescent probe materials. Background Art

[0002] Since World War I, chemical warfare agents (CWA S ) have become one of the most dangerous chemical weapons threatening global security due to their terrifying properties and unpredictable hazards. These chemicals are notorious for their extremely low biocompatibility and the potential to cause mass casualties. Chemical warfare agents are mainly divided into: nerve agents (NA S ), blister agents (BA S ), and choking agents (PA S ). Among these three types of agents, sarin, mustard gas, and phosgene are the most representative. Mustard gas, as a blister agent, can enter the human body through the eyes, skin, and respiratory tract, causing great harm. Phosgene, as a choking agent, can stimulate the human lungs, leading to pulmonary edema and respiratory failure, and eventually death. Among them, NA S is recognized as the most harmful chemical warfare agent due to its extreme toxicity and rapid lethality. Sarin, as one of the representative NAs, is volatile and can bind to the serine hydroxyl group of acetylcholinesterase (AChE) in the human body. After inhalation, it can inhibit the activity of AChE. This inhibition disrupts nerve conduction and ultimately leads to death. Although international bans on the use of chemical warfare agents have been promulgated, in the past few decades, they have still been employed in wars and conflicts, posing a major threat to national and public security. Therefore, the development of fluorescent probes that can be used to rapidly and accurately detect these three chemical warfare agents simultaneously has always been the main focus of research. Since sarin, mustard gas, and phosgene can cause serious harm to the human body, their analogs are usually selected for testing during experimental tests, such as: diethyl chlorophosphate (DCP), 2-chloroethyl ethyl sulfide (CEES), and triphosgene (TPG).

[0003] Due to the significant nucleophilicity of DCP, its detection can usually be achieved by phosphorylating or protonating hydroxyl groups, amino groups, and pyridines to change processes such as intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), excited-state intramolecular proton transfer (ESIPT), and photoinduced electron transfer (PET). However, for this type of fluorescent probe, it usually exhibits a rapid fluorescence response to DCP, but is severely interfered by proton acids, resulting in false positives in practical applications. Therefore, there is an urgent need to develop a new type of fluorescent probe to solve the interference of proton acids on DCP detection. Summary of the Invention

[0004] The object of the present invention is to solve the problem that existing fluorescent probes are seriously interfered by protonic acids, and to provide a preparation method and application of a highly selective fluorescent probe for chemical warfare agents based on free radicals.

[0005] A preparation method of a highly selective fluorescent probe for chemical warfare agents based on free radicals is specifically completed according to the following steps:

[0006] I. Preparation of CZ-DTE-Cl:

[0007] ①. Preparation of intermediate 1-1:

[0008] Glutaryl chloride and anhydrous aluminum trichloride are added to a round-bottom flask, then dichloromethane is added and stirred evenly. Then the round-bottom flask is placed in an ice-water bath and magnetically stirred for a period of time. Then a dichloromethane solution of 2-chloro-5-methylthiophene is added dropwise to the round-bottom flask. After the addition is completed, the ice bath is removed, and the system is allowed to react at room temperature for a period of time. After the reaction ends, the reaction is slowly quenched with ice water, and then extracted with a solvent. The organic phases are combined and washed with a solvent. The obtained organic layer is dried, concentrated, and passed through a column to obtain a pale yellow solid, which is intermediate 1-1.

[0009] ②. Preparation of intermediate 1-2:

[0010] Ⅰ. Intermediate 1-1 is dissolved in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-1.

[0011] Ⅱ. Zinc powder is added to a three-necked flask, then tetrahydrofuran is added and stirred evenly. Then the three-necked flask is placed in an ice-water bath, and titanium tetrachloride is added dropwise under a nitrogen atmosphere. After the addition is completed, nitrogen is filled and released three times to make the system under a nitrogen atmosphere. The temperature is raised to 68 °C and refluxed for a period of time, then the temperature is lowered to 40 °C, and then the tetrahydrofuran solution of intermediate 1-1 is added. The mixture is refluxed at 40 °C for a period of time. After the reaction ends, it is extracted with a solvent. The organic phases are combined and washed with a solvent. The obtained organic layer is dried, concentrated, and passed through a column to obtain intermediate 1-2.

[0012] ③. Preparation of the fluorescent probe-containing compound:

[0013] Ⅰ. Intermediate 1-2 is dissolved in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-2.

[0014] Ⅱ. The tetrahydrofuran solution of intermediate 1-2 is added to a three-necked flask, and nitrogen is evacuated and filled three times to make the system under a nitrogen atmosphere. Then the system is cooled to -78 °C and n-butyllithium is added. After the addition, the mixture is reacted at room temperature for a period of time, and then tributyl borate is added. Stirring is continued at room temperature for a period of time to obtain a reaction mixture.

[0015] III. Take a two-necked flask, add the carbazole derivative and tetrakis(triphenylphosphine)palladium, add a 20% potassium carbonate solution to the system. Under nitrogen protection, pour the reaction mixture in the three-necked flask in II into the two-necked flask, then react at 80 °C for a period of time, stop the reaction, cool to room temperature, filter off the tetrakis(triphenylphosphine)palladium, extract the filtered mixed solution with a solvent, combine the organic phases and wash with a solvent, dry the obtained organic layer, concentrate and pass through a column to obtain a white solid, which is CZ-DTE-Cl, that is, a fluorescent probe-containing substance;

[0016] II. Prepare a filter paper membrane by doping polyethylene oxide with CZ-DTE-Cl:

[0017] ①. Dissolve CZ-DTE-Cl in dichloromethane to obtain a dichloromethane solution of CZ-DTE-Cl;

[0018] ②. Add polyethylene oxide to the dichloromethane solution of CZ-DTE-Cl, and then stir until the solution is transparent and uniform to obtain a CZ-DTE-Cl-doped polyethylene oxide solution;

[0019] ③. Immerse the filter paper strip into the CZ-DTE-Cl-doped polyethylene oxide solution, stir for a period of time, take it out and spread it on a glass plate, and dry it naturally to obtain a highly selective chemical warfare agent fluorescent probe based on free radicals.

[0020] A highly selective chemical warfare agent fluorescent probe based on free radicals is used to detect mustard gas, phosgene or sarin, and has high selectivity.

[0021] The principle of the present invention:

[0022] The reaction involved in Step I① is the Friedel-Crafts acylation reaction. The reaction principle is that in the presence of a Lewis acid such as anhydrous aluminum trichloride, 2-chloro-5-methylthiophene reacts with glutaroyl chloride, and the hydrogen atom on the aromatic ring is replaced by an acyl group to form an aromatic ketone;

[0023] The reaction involved in Step I② is the McMurry reaction. The reaction principle is that first, titanium tetrachloride is reduced by zinc powder to low-valent titanium, and the titanium single electron transfers to the carbonyl group of intermediate 1-1 to initiate the reaction. Two electron-bearing carbonyl groups couple to obtain 1,2-diol, and then the diol continues to react with the complexed low-valent titanium to obtain an alkene;

[0024] The reaction involved in Step 1③ is lithiation borylation and Suzuki reaction. The reaction principle is that first, n-butyllithium is used as a catalyst to replace one chlorine on Intermediate 1-2 with tributyl borate to obtain the borylated Intermediate 1-2. Subsequently, the carbazole derivative undergoes oxidative addition with tetrakis(triphenylphosphine)palladium, and the palladium is oxidized from zero valence to +2 valence. The potassium carbonate solution is alkaline and reacts with the oxidative addition product to generate a highly active intermediate. Then, it undergoes transmetalation with the borylated Intermediate 1-2 to form a new intermediate, and after reductive elimination, CZ-DTE-Cl and zero-valent palladium are obtained.

[0025] The beneficial effects of the present invention are as follows:

[0026] First, compared with traditional fluorescent probes, the present invention is a novel radical-based sensing reaction;

[0027] Second, the present invention is a multifunctional fluorescent probe that can simultaneously achieve visual-fluorescent dual-mode detection of mustard gas, phosgene, and sarin mimics, with high selectivity;

[0028] Third, the probe of the present invention can distinguish between protonic acids and diethyl chlorophosphate (DCP), and there are obvious differences in both visible light and fluorescence colors between the two, solving the interference problem of protonic acids for DCP detection. Description of the Drawings

[0029] Figure 1 1H NMR spectrum of CZ-DTE-Cl prepared in Example 1;

[0030] Figure 2 High-resolution mass spectrum of CZ-DTE-Cl prepared in Example 1;

[0031] Figure 3 Electron paramagnetic resonance spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of DCP;

[0032] Figure 4 UV absorption spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of different analytes;

[0033] Figure 5 Fluorescence spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of different analytes;

[0034] Figure 6 Fluorescence spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of different interferents;

[0035] Figure 7 Fluorescence spectrum of CZ-DTE-Cl@PEO filter paper strip prepared in Example 1 in the presence of DCP;

[0036] Figure 8 The fluorescence spectrum of the CZ-DTE-Cl@PEO filter paper strip prepared in Example 1 in the presence of different interfering substances. Detailed implementation manners

[0037] Detailed implementation manner 1: A preparation method of a highly selective chemical warfare agent fluorescence probe based on free radicals is specifically completed according to the following steps:

[0038] I. Preparation of CZ-DTE-Cl:

[0039] ①. Preparation of intermediate 1-1:

[0040] Add glutaroyl chloride and anhydrous aluminum trichloride to a round-bottom flask, then add dichloromethane, stir evenly, then place the round-bottom flask in an ice-water bath, magnetically stir for a period of time, and then dropwise add the dichloromethane solution of 2-chloro-5-methylthiophene to the round-bottom flask. After the dropping is completed, remove the ice bath, allow the system to react at room temperature for a period of time. After the reaction ends, slowly quench the reaction with ice water, then perform solvent extraction, combine the organic phases and wash with a solvent, dry the obtained organic layer, concentrate and pass through a column to obtain a pale yellow solid, which is intermediate 1-1;

[0041] ②. Preparation of intermediate 1-2:

[0042] Ⅰ. Dissolve intermediate 1-1 in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-1;

[0043] Ⅱ. Add zinc powder to a three-necked flask, then add tetrahydrofuran, stir evenly, then place the three-necked flask in an ice-water bath, and dropwise add titanium tetrachloride under a nitrogen atmosphere. After the dropping is completed, purge nitrogen three times to make the system in a nitrogen atmosphere, heat up to 68 °C and reflux for a period of time, then lower the temperature to 40 °C, and then add the tetrahydrofuran solution of intermediate 1-1, reflux at 40 °C for a period of time. After the reaction ends, perform solvent extraction, combine the organic phases and wash with a solvent, dry the obtained organic layer, concentrate and pass through a column to obtain intermediate 1-2;

[0044] ③. Preparation of the fluorescence probe:

[0045] Ⅰ. Dissolve intermediate 1-2 in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-2;

[0046] Ⅱ. Add the tetrahydrofuran solution of intermediate 1-2 to a three-necked flask, purge and fill nitrogen three times to make the system in a nitrogen atmosphere, then cool the system to -78 °C and add n-butyllithium. After adding, react at room temperature for a period of time, then add tributyl borate, and continue to stir at room temperature for a period of time to obtain a reaction mixture;

[0047] III. Take a two-necked flask, add the carbazole derivative and tetrakis(triphenylphosphine)palladium, add a 20% potassium carbonate solution to the system. Under nitrogen protection, pour the reaction mixture in the three-necked flask in II into the two-necked flask, then react at 80 °C for a period of time, stop the reaction, cool to room temperature, filter off the tetrakis(triphenylphosphine)palladium, extract the filtered mixed solution with a solvent, combine the organic phases and wash with a solvent, dry the obtained organic layer, concentrate and column chromatograph to obtain a white solid, which is CZ-DTE-Cl, i.e., a fluorescent probe-containing substance;

[0048] II. Prepare a filter paper membrane by doping polyethylene oxide with CZ-DTE-Cl:

[0049] ①. Dissolve CZ-DTE-Cl in dichloromethane to obtain a dichloromethane solution of CZ-DTE-Cl;

[0050] ②. Add polyethylene oxide to the dichloromethane solution of CZ-DTE-Cl, and then stir until the solution is transparent and uniform to obtain a CZ-DTE-Cl-doped polyethylene oxide solution;

[0051] ③. Immerse the filter paper strip into the CZ-DTE-Cl-doped polyethylene oxide solution, stir for a period of time, take it out and spread it on a glass plate, and dry it naturally to obtain a highly selective fluorescent probe for chemical warfare agents based on free radicals.

[0052] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the molar ratio of glutaroyl chloride to aluminum trichloride in step ① of step one is 1:2; the molar ratio of glutaroyl chloride to 2-chloro-5-methylthiophene in step ① of step one is 1:(1-2); the molar amount of glutaroyl chloride in step ① of step one to the volume of dichloromethane is 0.1 mmol:(28.5 mL - 57 mL); the magnetic stirring time in step ① of step one is 20 min - 40 min; after the dropping is completed in step ① of step one, remove the ice bath and let the system react at room temperature for 1 h - 3 h; use a mixed solution of dichloromethane and water for extraction in step ① of step one, combine the organic phases and wash with deionized water, dry the obtained organic layer with anhydrous magnesium sulfate, concentrate and column chromatograph, and the eluent is a mixed solution of ethyl acetate and petroleum ether to obtain a pale yellow solid, which is Intermediate 1-1; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the volume ratio of ethyl acetate to petroleum ether in the mixed solution of ethyl acetate and petroleum ether is 1:10. Other steps are the same as those in Specific Embodiment 1.

[0053] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is as follows: In step 1②Ⅰ, the mass ratio of the intermediate 1-1 described to the volume of tetrahydrofuran is 1 g:(15 mL - 30 mL); in step 1②Ⅱ, the molar ratio of zinc powder to titanium tetrachloride is (2 - 3):1; in step 1②Ⅱ, the molar ratio of the intermediate 1-1 in the tetrahydrofuran solution of the intermediate 1-1 to titanium tetrachloride is 1:(3 - 4); in step 1②Ⅱ, the amount of substance of titanium tetrachloride to the volume of tetrahydrofuran is 1 mmol:(1 mL - 2 mL); in step 1②Ⅱ, a mixed solution of dichloromethane and water is used for extraction, the organic phases are combined and washed with deionized water, the obtained organic layer is dried with anhydrous magnesium sulfate, concentrated and passed through a column, and the eluent is petroleum ether to obtain the intermediate 1-2; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; in step 1②Ⅱ, the heating and temperature rising to 68 °C for refluxing is for 1 h - 2 h; in step 1②Ⅱ, the refluxing at 40 °C is for 1 h - 2 h. Other steps are the same as those in Specific Embodiment 1 or 2.

[0054] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is as follows: In step 1③Ⅰ, the dosage of the intermediate 1-2 described to the volume of tetrahydrofuran is 1 g:(4 mL - 6 mL); in step 1③Ⅱ, the volume ratio of n-butyllithium to tributyl borate is 1:1; in step 1③Ⅱ, the molar ratio of the amount of substance of the intermediate 1-2 in the tetrahydrofuran solution of the intermediate 1-2 to n-butyllithium is 1 mmol:(0.4 mL - 0.5 mL); in step 1③Ⅱ, the molar ratio of the intermediate 1-2 in the tetrahydrofuran solution of the intermediate 1-2 to the carbazole derivative described in step 1③Ⅲ is 1:1; in step 1③Ⅲ, the carbazole derivative is 3-bromo-9-phenylcarbazole, N-(2-naphthyl)-3-bromocarbazole or 9-(4-bromophenyl)carbazole. Other steps are the same as those in Specific Embodiments 1 to 3.

[0055] Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is as follows: In step 1③Ⅲ, the molar ratio of tetrakis(triphenylphosphine)palladium to the carbazole derivative is 1:(10 - 15); in step 1③Ⅲ, the volume ratio of the 20% potassium carbonate solution by mass to the n-butyllithium described in step 1③Ⅱ is (5 - 10):1; in step 1③Ⅱ, the system is cooled to -78 °C and then n-butyllithium is added. After adding, the reaction is carried out at room temperature for 10 min - 20 min, and then tributyl borate is added, and the mixture is continuously stirred at room temperature for 2 h - 4 h to obtain a reaction mixture. Other steps are the same as those in Specific Embodiments 1 to 4.

[0056] Specific Embodiment VI: The difference between this embodiment and any one of Specific Embodiments I to V is as follows: In step 1③Ⅲ, the reaction is carried out at 80 °C for 20 h to 24 h, then the reaction is stopped, cooled to room temperature, filtered, extracted with a mixed solution of dichloromethane and water, the organic phases are combined and washed with deionized water, the obtained organic layer is dried with anhydrous magnesium sulfate, concentrated and passed through a column, and the eluent is a mixed solution of dichloromethane and petroleum ether to obtain a white solid, which is CZ-DTE-Cl; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the volume ratio of dichloromethane to petroleum ether in the mixed solution of dichloromethane and petroleum ether is 1:10. Other steps are the same as those in Specific Embodiments I to V.

[0057] Specific Embodiment VII: The difference between this embodiment and any one of Specific Embodiments I to VI is as follows: In step 2①, the mass-volume ratio of CZ-DTE-Cl to dichloromethane is 1 mg:(5 mL to 15 mL); in step 2②, the volume ratio of CZ-DTE-Cl in the dichloromethane solution of CZ-DTE-Cl to polyethylene oxide is 1:200; in step 2③, the stirring time is 2 h to 3 h. Other steps are the same as those in Specific Embodiments I to VI.

[0058] Specific Embodiment VIII: This embodiment is a highly selective chemical warfare agent fluorescent probe based on free radicals for detecting mustard gas, phosgene or sarin, with high selectivity.

[0059] Specific Embodiment IX: The difference between this embodiment and any one of Specific Embodiments I to VIII is as follows: A highly selective chemical warfare agent fluorescent probe based on free radicals can distinguish protonic acid and diethyl chlorophosphate, and there is an obvious difference in their fluorescence colors. Other steps are the same as those in Specific Embodiments I to VIII.

[0060] Specific Embodiment X: The difference between this embodiment and any one of Specific Embodiments I to IX is as follows: When a highly selective chemical warfare agent fluorescent probe based on free radicals detects mustard gas, phosgene or sarin, visual-fluorescent dual-mode detection can be achieved. Other steps are the same as those in Specific Embodiments I to IX.

[0061] The following examples are used to verify the beneficial effects of the present invention:

[0062] Example 1: A preparation method of a highly selective chemical warfare agent fluorescent probe based on free radicals is specifically completed according to the following steps:

[0063] I. Preparation of CZ-DTE-Cl:

[0064] ①. Preparation of intermediate 1-1:

[0065] Glutaryl chloride and anhydrous aluminum trichloride were added to a round-bottom flask, followed by dichloromethane. The mixture was stirred evenly, and then the round-bottom flask was placed in an ice-water bath and magnetically stirred for 30 min. Then, a dichloromethane solution of 2-chloro-5-methylthiophene was added dropwise to the round-bottom flask. After the addition was complete, the ice bath was removed, and the system was allowed to react at room temperature for 2 h. After the reaction was completed, the reaction was slowly quenched with ice water, and extraction was carried out using a mixed solution of dichloromethane and water. The organic phases were combined and washed with deionized water. The obtained organic layer was dried over anhydrous magnesium sulfate, concentrated, and purified by column chromatography. The eluent was a mixed solution of ethyl acetate and petroleum ether, and a pale yellow solid, namely intermediate 1-1 (yield 80%), was obtained.

[0066] In the mixed solution of dichloromethane and water described in step ①, the volume ratio of dichloromethane to water is 3:1; in the mixed solution of ethyl acetate and petroleum ether, the volume ratio of ethyl acetate to petroleum ether is 1:10.

[0067] In step ①, the molar ratio of glutaryl chloride to aluminum trichloride is 1:2.

[0068] In step ①, the molar ratio of glutaryl chloride to 2-chloro-5-methylthiophene is 1:1.5.

[0069] In step ①, the molar amount of glutaryl chloride to the volume of dichloromethane is 0.1 mmol:28.5 mL.

[0070] The reaction equation of step ① is as follows:

[0071]

[0072] ②. Preparation of intermediate 1-2:

[0073] Ⅰ. Dissolve intermediate 1-1 (1.8 g, 5.0 mmol) in 36 mL of tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-1.

[0074] II. Add zinc powder (3.0 g, 46.15 mmol) into a three-necked flask, then add 20 mL of tetrahydrofuran, stir evenly, and place the three-necked flask in an ice-water bath. Under a nitrogen atmosphere, add titanium tetrachloride (4.0 mL, 18.6 mmol) dropwise. After the addition is completed, purge nitrogen three times to make the system under a nitrogen atmosphere. Heat up to 68 °C and reflux for 1 h, then cool the temperature to 40 °C. Then add the tetrahydrofuran solution of intermediate 1-1 obtained in I, reflux at 40 °C for 1 h. After the reaction is completed, extract with a mixed solution of dichloromethane and water (3 × 45 mL), combine the organic phases and wash with deionized water. Dry the obtained organic layer with anhydrous magnesium sulfate, concentrate and column chromatograph (200 - 300 mesh silica gel), and the eluent is petroleum ether to obtain intermediate 1-2 (1.2 g, yield 80%); the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1;

[0075] The reaction equation of step 1② is as follows:

[0076]

[0077] ③. Prepare the fluorescent probe:

[0078] I. Dissolve intermediate 1-2 (1.32 g, 4.0 mmol) in 5.5 mL of tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-2;

[0079] II. Add the tetrahydrofuran solution of intermediate 1-2 into a three-necked flask, purge nitrogen three times to make the system under a nitrogen atmosphere, then cool the system to -78 °C and add n-butyllithium (1.6 mL). After the addition, react at room temperature for 15 min, then add tributyl borate (1.6 mL), and continue to stir at room temperature for 3 h to obtain a reaction mixture;

[0080] Ⅲ. Take a two-necked flask, add 3-bromo-9-phenylcarbazole (1.29 g, 4 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.28 g, 0.24 mmol), add 12 mL of a 20% potassium carbonate solution to the system. Under nitrogen protection, pour the reaction mixture in the three-necked flask in II into the two-necked flask, then react at 80 °C for 24 h, stop the reaction, cool to room temperature, filter off tetrakis(triphenylphosphine)palladium(0). The filtered mixed solution is extracted with a mixed solution of dichloromethane and water (3 × 45 mL), the organic phases are combined and washed with deionized water (45 mL), the obtained organic layer is dried with anhydrous magnesium sulfate, concentrated and passed through a column (200 - 300 mesh silica gel), and the eluent is a mixed solution of dichloromethane and petroleum ether to obtain a white solid (0.6 g, yield 50%), which is CZ-DTE-Cl; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the volume ratio of dichloromethane to petroleum ether in the mixed solution of dichloromethane and petroleum ether is 1:10;

[0081] The reaction equation of Step ①③ is as follows:

[0082]

[0083] II. Prepare a filter paper membrane by doping polyethylene oxide with CZ-DTE-Cl:

[0084] ①. Dissolve 3 mg of CZ-DTE-Cl in 30 mL of dichloromethane to obtain a dichloromethane solution of CZ-DTE-Cl;

[0085] ②. Add 600 mg of polyethylene oxide to the dichloromethane solution of CZ-DTE-Cl, and then stir until the solution is transparent and uniform to obtain a CZ-DTE-Cl doped polyethylene oxide solution;

[0086] ③. Immerse the filter paper strip into the CZ-DTE-Cl doped polyethylene oxide solution, stir for 2 h, take it out and spread it on a glass plate, and dry it naturally to obtain a high-selectivity chemical warfare agent fluorescent probe based on free radicals (CZ-DTE-Cl@PEO filter paper strip).

[0087] The ¹H NMR spectrum of CZ-DTE-Cl prepared in Example 1 is as Figure 1 shown;

[0088] Figure 1 is the ¹H NMR spectrum of CZ-DTE-Cl prepared in Example 1;

[0089] The ¹H NMR spectrum was recorded using deuterated chloroform as the deuterated reagent. After integration, the doublets at 8.12 ppm, 8.02 ppm, the multiplets at 7.60 - 7.30 ppm, 7.32 - 7.27 ppm, and the multiplets at 7.21 ppm and 7.15 ppm were attributed to the hydrogens on benzocarbazole. The singlets at 6.91 ppm, 6.54 ppm, the doublet at 1.90 ppm, and the singlet at 1.79 ppm were attributed to the hydrogens of the two thiophenes. The multiplets at 2.76 - 2.69 ppm, 2.65 - 2.58 ppm, the multiplet at 1.96 - 1.91 ppm, and the singlet at 1.79 ppm were attributed to the hydrogens of cyclopentene. And the total number of hydrogens after integration was 26, corresponding to the number of hydrogens in the molecule, indicating that CZ-DTE-Cl was successfully synthesized.

[0090] The high-resolution mass spectrum of CZ-DTE-Cl prepared in Example 1 is as Figure 2 shown;

[0091] Figure 2 is the high-resolution mass spectrum of CZ-DTE-Cl prepared in Example 1;

[0092] From Figure 2 it can be seen that the peak data in the high-resolution mass spectrum are test data, and the molecular weight result is 535.142, which is basically consistent with the actual molecular weight M = 536, proving that the CZ-DTE-Cl product was successfully synthesized.

[0093] The electron paramagnetic resonance spectrum (EPR) of CZ-DTE-Cl in the presence of DCP is as Figure 3 shown; Figure 3 is the electron paramagnetic resonance spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of DCP;

[0094] The toluene solution (20 g / mL) of CZ-DTE-Cl prepared in Example 1 could recognize a tiny EPR signal in the dark. Meanwhile, with the stimulation of ultraviolet light, the luminescent free radical signal gradually increased. The g value of the free radical signal was 2.0029, close to the signal of free electrons (2.0023). After adding 50 μL of DCP solution to the toluene solution of CZ-DTE-Cl, a weak EPR signal also existed under dark conditions. After ultraviolet light stimulation, fluorescence quenched but the same free radical signal as the luminescent free radical was generated, with the same g value. This indicates that the same free radical species were generated before and after adding DCP.

[0095] The ultraviolet absorption spectrum of CZ-DTE-Cl in the presence of different analytes is as Figure 4 shown; Figure 4The UV absorption spectra of CZ-DTE-Cl prepared in Example 1 in the presence of different analytes;

[0096] After the dichloro solution of CZ-DTE-Cl (1×10 -5 mol / L) was irradiated with ultraviolet light for 20 s, the solution changed from colorless to red, and a new absorption peak appeared at 450 - 550 nm, which corresponded to the absorption peak of the photoproduct of dithienylethene. At the same time, the UV absorption intensity increased at 550 - 700 nm, indicating the generation of new radical species in the solution. 50 μL of diethyl chlorophosphate (DCP), 2-chloroethyl ethyl sulfide (CEES), triphosgene (TPG), and hydrochloric acid (HCl) at 1×10 -2 mol / L were respectively added to the original solution and irradiated with ultraviolet light for the same time. The solutions changed from colorless to blue, colorless to purple, colorless to purple, and colorless to red, respectively. At the same time, it was found that the same red-shifted absorption peak as that of the original solution without analytes under light irradiation appeared in the solution, proving that the same radical species were generated in the solution after adding analytes.

[0097] The fluorescence spectra of CZ-DTE-Cl in the presence of different analytes are as Figure 5 shown; Figure 5 The fluorescence spectra of CZ-DTE-Cl prepared in Example 1 in the presence of different analytes; After the dichloro solution of CZ-DTE-Cl (1×10 -5 mol / L) was irradiated with ultraviolet light for 20 s, the fluorescence color of the solution changed from bright blue to bright orange, and two emission peaks appeared at 475 nm and 600 nm. When 15 μL, 18 μL, and 21 μL (1×10 -2 mol / L) of DCP solution were respectively added to the dichloro solution of CZ-DTE-Cl and irradiated for the same time, the fluorescence color of the solution changed from bright blue to light blue. Compared with the dichloro solution of CZ-DTE-Cl without DCP after light irradiation, the peak at 600 nm disappeared, and only a weak emission peak at 475 nm remained. When 15 μL, 18 μL, and 21 μL (1×10 -2 mol / L) of HCl solution were respectively added to the dichloro solution of CZ-DTE-Cl and irradiated for the same time, the fluorescence color of the solution changed from bright blue to bright orange. Compared with the dichloro solution of CZ-DTE-Cl without HCl after light irradiation, the peak at 600 nm was slightly enhanced, and the emission peak at 475 nm remained unchanged. When 15 μL, 18 μL, and 21 μL (1×10 - 2After adding the TPG solution ( -2 mol / L) and irradiating for the same time, the fluorescence color of the solution changed from bright blue to orange-yellow. Compared with the emission peak at 600 nm of the dichloromethane solution of CZ-DTE-Cl without TPG after irradiation, the emission peak decreased, and the emission peak at 475 nm remained unchanged. When 15 μL, 18 μL, and 21 μL (1×10

[0098] The fluorescence spectra of CZ-DTE-Cl in the presence of different interferents are as Figure 6 shown; Figure 6 This is the fluorescence spectrum of CZ-DTE-Cl prepared in Example 1 in the presence of different interferents. Through fluorescence titration tests, it was found that the fluorescence response of the dichloromethane solution of CZ-DTE-Cl (1×10 -5 mol / L) to other phosphorus-containing interferents was significantly lower than that to DCP. Moreover, when CZ-DTE-Cl was exposed to hydrochloric acid, the emission peak at 600 nm showed an increasing trend, indicating that this fluorescent probe has high selectivity for DCP detection.

[0099] The fluorescence spectrum of CZ-DTE-Cl@PEO paper strip in the presence of DCP is as Figure 7 shown; Figure 7 This is the fluorescence spectrum of the CZ-DTE-Cl@PEO filter paper strip prepared in Example 1 in the presence of DCP. Eleven CZ-DTE-Cl PEO filter paper strips of the same size were taken and kept under the same irradiation conditions, and different amounts of DCP vapor were introduced. By observing the fluorescence spectra, it can be seen that as the amount of DCP vapor increased, the emission peak at 600 nm in the fluorescence spectra decreased. When DCP was not added, with ultraviolet light irradiation, the CZ-DTE-Cl@PEO filter paper strip produced an emission peak at 600 nm, indicating that luminescent radical species were generated in the system. When DCP was added, with ultraviolet light irradiation, the emission peak at 600 nm quenched, indicating that after adding DCP, DCP combined with the fluorescent probe, making the radical species non-luminescent.

[0100] The fluorescence spectra of CZ-DTE-Cl@PEO filter paper strip in the presence of different interferents are as Figure 8 shown; Figure 8Fluorescence spectra of the CZ-DTE-Cl@PEO filter paper prepared in Example 1 in the presence of different interfering substances; it was found that the quenching degree of the emission peak at 600 nm of the CZ-DTE-Cl@PEO filter paper in the vapors of other phosphorus-containing interfering substances was lower than that of the DCP solution, and the emission peak at 600 nm was slightly enhanced in the vapor of HCl. This indicates that the fluorescence probe has high selectivity for DCP detection.

Claims

1. A preparation method of a radical-based highly selective fluorescent probe for chemical warfare agents, characterized in that The preparation method is specifically completed according to the following steps: I. Preparation of CZ-DTE-Cl: ①. Preparation of intermediate 1-1: Glutaroyl chloride and anhydrous aluminum trichloride are added to a round-bottom flask, and then dichloromethane is added and stirred evenly. Then the round-bottom flask is placed in an ice-water bath and magnetically stirred for a period of time. Then a dichloromethane solution of 2-chloro-5-methylthiophene is added dropwise to the round-bottom flask. After the addition is completed, the ice bath is removed, and the system is allowed to react at room temperature for a period of time. After the reaction ends, the reaction is slowly quenched with ice water, and then extracted with a solvent. The organic phases are combined and washed with a solvent. The obtained organic layer is dried, concentrated, and passed through a column to obtain a pale yellow solid, which is intermediate 1-1. ②. Preparation of intermediate 1-2: Ⅰ. Intermediate 1-1 is dissolved in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-1. Ⅱ. Zinc powder is added to a three-necked flask, and then tetrahydrofuran is added and stirred evenly. Then the three-necked flask is placed in an ice-water bath, and titanium tetrachloride is added dropwise under a nitrogen atmosphere. After the addition is completed, nitrogen is filled and released three times to make the system under a nitrogen atmosphere. The temperature is raised to 68 °C and refluxed for a period of time, and then the temperature is lowered to 40 °C. Then the tetrahydrofuran solution of intermediate 1-1 is added, and the mixture is refluxed at 40 °C for a period of time. After the reaction ends, it is extracted with a solvent. The organic phases are combined and washed with a solvent. The obtained organic layer is dried, concentrated, and passed through a column to obtain intermediate 1-2. ③. Preparation of the fluorescent probe-containing: Ⅰ. Intermediate 1-2 is dissolved in tetrahydrofuran to obtain a tetrahydrofuran solution of intermediate 1-2. Ⅱ. The tetrahydrofuran solution of intermediate 1-2 is added to a three-necked flask, and nitrogen is evacuated and filled three times to make the system under a nitrogen atmosphere. Then the system is cooled to -78 °C and n-butyllithium is added. After the addition, the mixture is allowed to react at room temperature for a period of time, and then tributyl borate is added, and the mixture is continuously stirred at room temperature for a period of time to obtain a reaction mixture. Ⅲ. Take a two-necked flask, add a carbazole derivative and palladium tetrakis(triphenylphosphine), and add a 20% potassium carbonate solution to the system. Under nitrogen protection, the reaction mixture in the three-necked flask in II is poured into the two-necked flask, and then the mixture is reacted at 80 °C for a period of time. The reaction is stopped and cooled to room temperature. Palladium tetrakis(triphenylphosphine) is filtered off. The filtered mixed solution is extracted with a solvent. The organic phases are combined and washed with a solvent. The obtained organic layer is dried, concentrated, and passed through a column to obtain a white solid, which is CZ-DTE-Cl, that is, the fluorescent probe-containing. II. Preparation of a filter paper membrane by doping polyethylene oxide with CZ-DTE-Cl: ①. CZ-DTE-Cl is dissolved in dichloromethane to obtain a dichloromethane solution of CZ-DTE-Cl. ②. Polyethylene oxide is added to the dichloromethane solution of CZ-DTE-Cl, and then stirred until the solution is transparent and uniform to obtain a CZ-DTE-Cl-doped polyethylene oxide solution. ③. The filter paper strip is immersed in the CZ-DTE-Cl-doped polyethylene oxide solution, stirred for a period of time, taken out and spread on a glass plate, and naturally dried to obtain a highly selective fluorescent probe for chemical warfare agents based on free radicals.

2. The preparation method of a high-selectivity chemical warfare agent fluorescent probe based on free radicals according to claim 1, wherein The molar ratio of glutaroyl chloride to aluminum trichloride described in Step 1① is 1:2; the molar ratio of glutaroyl chloride to 2-chloro-5-methylthiophene described in Step 1① is 1:(1 - 2); the molar ratio of the amount of substance of glutaroyl chloride described in Step 1① to the volume of dichloromethane is 0.1 mmol:(28.5 mL - 57 mL); the time of magnetic stirring described in Step 1① is 20 min - 40 min; after the dropping is completed in Step 1①, the ice bath is removed, and the reaction time of the system at room temperature is 1 h - 3 h; in Step 1①, a mixed solution of dichloromethane and water is used for extraction, the organic phases are combined and washed with deionized water, anhydrous magnesium sulfate is used to dry the obtained organic layer, concentrated and passed through a column, and the eluent is a mixed solution of ethyl acetate and petroleum ether to obtain a pale yellow solid, which is Intermediate 1-1; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the volume ratio of ethyl acetate to petroleum ether in the mixed solution of ethyl acetate and petroleum ether is 1:

10.

3. The preparation method of a highly selective chemical warfare agent fluorescent probe based on free radicals according to claim 1, characterized in that The mass-to-volume ratio of Intermediate 1-1 described in Step 1②Ⅰ is 1 g:(15 mL - 30 mL); the molar ratio of zinc powder to titanium tetrachloride described in Step 1②Ⅱ is (2 - 3):1; the molar ratio of Intermediate 1-1 to titanium tetrachloride in the tetrahydrofuran solution of Intermediate 1-1 described in Step 1②Ⅱ is 1:(3 - 4); the molar ratio of the amount of substance of titanium tetrachloride described in Step 1②Ⅱ to the volume of tetrahydrofuran is 1 mmol:(1 mL - 2 mL); in Step 1②Ⅱ, a mixed solution of dichloromethane and water is used for extraction, the organic phases are combined and washed with deionized water, anhydrous magnesium sulfate is used to dry the obtained organic layer, concentrated and passed through a column, and the eluent is petroleum ether to obtain Intermediate 1-2; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the reflux time when heating up to 68 °C in Step 1②Ⅱ is 1 h - 2 h; the reflux time at 40 °C in Step 1②Ⅱ is 1 h - 2 h.

4. The preparation method of a highly selective chemical warfare agent fluorescent probe based on free radicals according to claim 1, characterized in that The dosage-to-volume ratio of Intermediate 1-2 described in Step 1③Ⅰ is 1 g:(4 mL - 6 mL); the volume ratio of n-butyllithium to tributyl borate described in Step 1③Ⅱ is 1:1; the volume ratio of the amount of substance of Intermediate 1-2 in the tetrahydrofuran solution of Intermediate 1-2 described in Step 1③Ⅱ to n-butyllithium is 1 mmol:(0.4 mL - 0.5 mL); the molar ratio of Intermediate 1-2 in the tetrahydrofuran solution of Intermediate 1-2 described in Step 1③Ⅱ to the carbazole derivative described in Step 1③Ⅲ is 1:1; the carbazole derivative described in Step 1③Ⅲ is 3-bromo-9-phenylcarbazole, N-(2-naphthyl)-3-bromocarbazole or 9-(4-bromophenyl)carbazole.

5. A method for preparing a highly selective fluorescent probe for chemical warfare agents based on free radicals according to claim 1, characterized in that In Step 1(3)(III), the molar ratio of tetrakis(triphenylphosphine)palladium to the carbazole derivative is 1:(10 - 15); in Step 1(3)(III), the volume ratio of the potassium carbonate solution with a mass fraction of 20% to the n-butyllithium in Step 1(3)(II) is (5 - 10):1; in Step 1(3)(II), after cooling the system to -78 °C, n-butyllithium is added, and after the addition, the reaction is carried out at room temperature for 10 min - 20 min, then tributyl borate is added, and the mixture is continuously stirred at room temperature for 2 h - 4 h to obtain a reaction mixture.

6. The preparation method of a high-selectivity chemical warfare agent fluorescent probe based on free radicals according to claim 1, characterized in that In Step 1(3)(III), the reaction is carried out at 80 °C for 20 h - 24 h, the reaction is stopped, cooled to room temperature, filtered, extracted with a mixed solution of dichloromethane and water, the organic phases are combined and washed with deionized water, the obtained organic layer is dried with anhydrous magnesium sulfate, concentrated and passed through a column, and the eluent is a mixed solution of dichloromethane and petroleum ether to obtain a white solid, which is CZ-DTE-Cl; the volume ratio of dichloromethane to water in the mixed solution of dichloromethane and water is 3:1; the volume ratio of dichloromethane to petroleum ether in the mixed solution of dichloromethane and petroleum ether is 1:

10.

7. The preparation method of a radical-based highly selective chemical warfare agent fluorescent probe according to claim 1, characterized in that In Step 2(1), the mass-volume ratio of CZ-DTE-Cl to dichloromethane is 1 mg:(5 mL - 15 mL); in Step 2(2), the volume ratio of CZ-DTE-Cl in the dichloromethane solution of CZ-DTE-Cl to polyethylene oxide is 1:200; in Step 2(3), the stirring time is 2 h - 3 h.

8. Use of a radical-based highly selective chemical warfare agent fluorescent probe prepared by the preparation method according to claim 1, characterized in that A highly selective chemical warfare agent fluorescent probe based on free radicals is used for detecting mustard gas, phosgene or sarin and has high selectivity.

9. Use of a radical-based highly selective chemical warfare agent fluorescent probe according to claim 8, characterized in that A highly selective chemical warfare agent fluorescent probe based on free radicals can distinguish protonic acid and diethyl chlorophosphate, and there are obvious differences in their fluorescence colors.

10. Use of a radical-based highly selective chemical warfare agent fluorescent probe according to claim 8, characterized in that When a highly selective chemical warfare agent fluorescent probe based on free radicals detects mustard gas, phosgene or sarin, visual-fluorescence dual-mode detection can be achieved.

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