Polymer fluorescent sensing film for detecting neurotoxic agent sarin simulant as well as preparation method and application of polymer fluorescent sensing film

Abstract

The invention discloses a polymer fluorescent sensing film for detecting a neurotoxic agent sarin simulant as well as a preparation method and application of the polymer fluorescent sensing film. The polymer fluorescent sensing film is prepared by crosslinking an acylhydrazone bond formed by bis-p-phenylene dihydrazide connected with a polyethylene glycol chain and tetraphenyl ethylene terephthalaldehyde through a Schiff base reaction. The polymer fluorescent sensing film has the excellent properties of both the polyethylene glycol chain and the tetraphenyl ethylene, the introduction of the polyethylene glycol chain enables the film to have more excellent flexibility, and the introduction of the tetraphenyl ethylene enables the film to have richer luminescent properties and better photochemical stability. The polymer fluorescent sensing film shows ultra-sensitive, high-selectivity, rapid and recoverable response to a nerve toxic agent sarin simulant diethyl chlorophosphate, has a detection limit of 1 ppt for diethyl chlorophosphate, has high anti-interference capability for hydrochloric acid and other volatile organic compounds, and can be used for detecting the nerve toxic agent sarin.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent sensor films, and in particular relates to a polymer fluorescent sensor film for detecting diethyl chlorophosphate, a neurotoxin simulant. The polymer fluorescent sensor film is prepared by cross-linking acylhydrazone bonds formed by Schiff base reaction of bis(terephthaloyl)hydrazide and tetraphenylethylene terephthalate tetracarboxaldehyde connected by polyethylene glycol chains. Background Art

[0002] Sarin is a highly toxic volatile nerve agent. After inhalation or skin contact, its active phosphorus-containing group will react irreversibly with the hydroxyl group of acetylcholinesterase in the body, resulting in the inactivation of acetylcholinesterase. Real-time, online, rapid and selective detection of sarin is of great significance to national security, public safety and international peace. The development and improvement of detection methods are crucial to prevent the use of sarin, protect people from harm, and maintain international agreements aimed at prohibiting chemical weapons. A variety of detection methods have been used to detect nerve agents such as sarin, including colorimetry, interferometry, electrochemistry, surface acoustic wave devices, photoacoustic spectroscopy, enzyme assays, and gas chromatography-mass spectrometry. However, these methods have their limitations, such as low reactivity and sensitivity, limited selectivity, lack of specificity, inconvenience in portability, difficulty in real-time detection, false positive display, and complex operation.

[0003] According to the list of the top ten emerging technologies in chemistry released by the International Union of Pure and Applied Chemistry in 2022, thin-film fluorescence sensors were rated as "tunable and versatile alternative technologies that provide miniaturized detector solutions", and thus have become a highly anticipated technology in the current field of chemical research. This sensor has the advantages of simple operation, high sensitivity, low cost and real-time response. Due to its effectiveness in a variety of media, it is widely used in chemical analysis and detection in different fields. Compared with traditional solutions, thin-film, sheet or strip sensors are easier to install and more fully contact with the gas to be measured, so they have significant advantages in gas detection. Summary of the invention

[0004] The present invention aims to provide a polymer fluorescent nanofilm cross-linked by acylhydrazone bonds formed by Schiff base reaction of bis(terephthaloyl)hydrazide connected by polyethylene glycol chains and tetraphenylethylene terephthalaldehyde as a chromophore. The fluorescent sensing film achieves sensitive response to diethyl chlorophosphate (DCP), a sarin simulant, and has fast response speed, good selectivity and good recovery.

[0005] The structural unit of the polymer in the polymer fluorescent sensor film provided by the present invention is as follows:

[0006]

[0007] The preparation method of the polymer fluorescent sensor film comprises the following steps:

[0008] Step 1: Add PEG-400, p-toluenesulfonyl chloride and potassium hydroxide to dichloromethane, react at room temperature for 12 to 24 hours in a nitrogen atmosphere, quench the reaction with water after the reaction is completed, separate and purify to obtain compound 1 based on polyethylene glycol chain connection;

[0009]

[0010] Step 2: Compound 1, 2-hydroxyterephthalate and potassium carbonate are added to acetone, and the mixture is reacted at 60-80° C. for 48-60 hours in a nitrogen atmosphere. After the reaction is completed, the mixture is cooled to room temperature, separated and purified to obtain diterephthalate connected by a polyethylene glycol chain, which is recorded as DTH-dimer-400-ester;

[0011]

[0012] Step 3: Add DTH-dimer-400-ester and excess hydrazine hydrate into methanol, react at 70-80° C. in a nitrogen atmosphere for 5-6 days, cool to room temperature after the reaction is completed, separate and purify to obtain bis(terephthaloyl)hydrazide connected by polyethylene glycol chains, recorded as DTH-dimer-400;

[0013]

[0014] Step 4: Dissolve DTH-dimer-400 and tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TTPE) in DMSO, and drip the resulting mixed solution onto a glass plate to spread it completely; then place the glass plate in a constant temperature and humidity biochemical incubator for film-forming reaction; take out the plate after reacting for 24 to 36 hours, and after the solution is completely evaporated, place the glass plate in deionized water to obtain the polymer fluorescent sensing film;

[0015]

[0016] In the above step 1, the molar ratio of PEG-400, p-toluenesulfonyl chloride and potassium hydroxide is preferably 1:2-2.5:3-4.

[0017] In the above step 2, the molar ratio of the compound 1, 2-hydroxyterephthalate and potassium carbonate is preferably 1:2.8-3.5:4-4.5.

[0018] In the above step 3, the molar ratio of the DTH-dimer-400-ester to hydrazine hydrate is preferably 1:50-80.

[0019] In the above step 4, the molar ratio of DTH-dimer-400 to tetrakis-(4-formyl-(1,1-biphenyl))ethylene is preferably 1 to 1.5:1.

[0020] The present invention also provides the use of the polymer fluorescent sensor film for detecting diethyl chlorophosphate, a neurotoxin simulant of sarin.

[0021] The beneficial effects of the present invention are as follows:

[0022] The polymer fluorescent sensor film of the present invention, which is based on bis-terephthaloyl hydrazide synthesized by polyethylene glycol and connected with tetraphenylethylene tetrabenzaldehyde as a chromophore, realizes sensitive response to diethyl chlorophosphate, a nerve agent sarin simulant, and the detection limit of diethyl chlorophosphate can be as low as 1ppt, and the response speed is fast, the selectivity is good, and the recovery is good. It not only provides a basis for the real-time visual detection of the nerve agent sarin, but also the low detection limit of 1ppt and the anti-interference ability to other volatile organic compounds are lower than the detection limit of the nerve agent sarin by the self-supporting flexible film reported in previous studies, and far lower than the concentration of 7ppb at which the nerve agent sarin poses a direct threat to human life and health, so that the fluorescent sensor film is expected to construct a new type of portable sensor for the nerve agent sarin monitoring, thereby realizing the early diagnosis of the nerve agent sarin. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the compound 1 prepared in Example 1 1 H NMR spectrum.

[0024] Figure 2 is the DTH-dimer-400-ester prepared in Example 1 1 H NMR spectrum.

[0025] Figure 3 It is DTH-dimer-400 prepared in Example 1 1 H NMR spectrum.

[0026] Figure 4 The fluorescence excitation and emission spectra of the polymer fluorescence sensing film TTPE-DTH-400-G prepared in Example 1 are shown.

[0027] Figure 5 1 is the emission spectrum of the polymer fluorescent sensing film TTPE-DTH-400-G prepared in Example 1 before and after DCP vapor purge.

[0028] Figure 6 This is a field emission scanning electron microscope image of the polymer fluorescent sensor film TTPE-DTH-400-G prepared in Example 1.

[0029] Figure 7 FT-IR spectra of the polymer fluorescent sensing film TTPE-DTH-400-G and the monomer prepared in Example 1.

[0030] Figure 8 This is the XPS spectrum of the polymer fluorescent sensing film TTPE-DTH-400-G prepared in Example 1.

[0031] Fig. 9 This is the fluorescence intensity variation spectrum of the polymer fluorescent sensor film TTPE-DTH-400-G prepared in Example 1 at a specified wavelength when detecting DCP gas of different concentrations (excitation light 440nm, monitoring wavelength 525nm).

[0032] Fig.10 This is the selectivity test result of the polymer fluorescent sensing film TTPE-DTH-400-G prepared in Example 1, wherein 1 is acetone, 2 is dichloromethane, 3 is 1,4-dioxane, 4 is ethyl acetate, 5 is methanol, 6 is acetonitrile, 7 is chloroform, 8 is tetrahydrofuran, 9 is toluene, 10 is benzaldehyde, 11 is ethanol, 12 is triethylamine, 13 is ammonia, 14 is acetic acid, 15 is formic acid, 16 is hydrochloric acid, and 17 is diethyl chlorophosphate, all of which are vapors with a concentration of 100 ppm. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0034] Example 1

[0035] Step 1: Accurately weigh 2g (5mmol, 1eq) of PEG-400 and put it into a dry 100mL double-mouth round-bottom flask. Use a double-row tube system to thoroughly deoxygenate the system and introduce nitrogen to ensure that the entire reaction process is carried out under nitrogen protection. Then add 10mL of dichloromethane as a solvent, followed by 2.39g (12.5mmol, 2.5eq) of p-toluenesulfonyl chloride, place the reaction system in an ice bath at 0°C, add 1.12g (20mmol, 4eq) of dry potassium hydroxide, and continue stirring at room temperature for 12 hours. After the reaction is completed, add 25mL of ultrapure water to the system, continue stirring to quench the reaction, and then separate the organic phase from the aqueous phase through a separatory funnel, and retain the organic phase. The organic phase was extracted from the aqueous phase three times with dichloromethane, and the organic phases were combined; the organic phase was then extracted and washed three times with hydrochloric acid, and then extracted three times with sodium chloride aqueous solution, and the extracted organic phase was dried with anhydrous magnesium sulfate, the magnesium sulfate was removed by suction filtration, and the dichloromethane was completely removed by rotary evaporation, and finally a colorless viscous liquid compound 1 was obtained. It was determined that the yield of compound 1 was 72%.

[0036] The structural characterization data of the obtained compound 1 are: 1 H NMR (600 MHz, CDCl 3 ,298K)δ(ppm):7.79(d,J=7.6Hz,4H),7.34(d,J=7.9Hz,4H),4.15(dd,J=9.0,4.4Hz,4H),3.69-3.57(m,32H),2.44(d,J=4.0Hz,6H), see Figure 1 .

[0037] Step 2: 750 mg (1.04 mmol, 1 eq) of compound 1, 651 mg (3.17 mmol, 3 eq) of 2-hydroxyterephthalate and 575 mg (4.16 mmol, 4 eq) of potassium carbonate were added to a 50 mL double-necked round-bottom flask, and the oxygen in the system was removed and replaced with nitrogen using a double-row tube system. 10 mL of acetone was added, and the reaction was stirred at 60 ° C for 48 hours, cooled to room temperature, and the acetone was removed by rotary evaporation. Dichloromethane was added to completely dissolve the product, and then 1 mol / L potassium hydroxide aqueous solution was added as the aqueous phase for extraction and washing. The organic phases were combined and dried with anhydrous magnesium sulfate, and magnesium sulfate was removed by suction filtration. The filtrate was subjected to rotary evaporation to remove dichloromethane. The product was purified using column chromatography, and the developing solvent volume ratio was gradually increased from dichloromethane: methanol = 150: 1 to 50: 1. The purified product was vacuum dried to obtain a yellow-brown viscous liquid DTH-dimer-400-ester with a yield of 53%.

[0038] The structural characterization data of the obtained DTH-dimer-400-ester are: 1 H NMR (600 MHz, CDCl 3 ,298K)δ(ppm):7.79(d,J=7.8Hz,2H),7.64(dd,J=7.8Hz,3.7Hz,4H),4.26(dd,J=9.0,4.4Hz,4H),3.96-3.86(m,16H),3.80-3.58(m,27H), see Figure 2 .

[0039] Step 3: Weigh 250 mg (0.3 mmol, 1 eq) of DTH-dimer-400-ester into a 50 mL round-bottomed double-necked flask, use a double-row tube system to remove oxygen in the system and replace it with nitrogen, add 10 mL of methanol, then inject 2 mL (16 mmol, 50 eq) of hydrazine hydrate into it, and stir and react at 70 ° C under nitrogen protection for 6 days. After the reaction system is cooled to room temperature, the methanol and part of the hydrazine hydrate are removed by rotary evaporation, and then freeze-dried to remove the remaining hydrazine hydrate, and finally a brown colloidal solid product DTH-dimer-400 is obtained with a yield of 80%.

[0040] The structural characterization data of the obtained DTH-dimer-400 are: 1 H NMR (600 MHz, DMSO-d 6 ,298K)δ(ppm):9.90(s,2H),9.28(s,2H),7.81(d,J=8.0Hz,2H),7.55(s,2H),7.49(d,J=8.0H z, 2H), 4.58 (s, 8H), 4.29 (dd, J = 9.0, 4.4Hz, 4H), 3.81 (d, J = 3.7Hz, 4H), 3.65-3.43 (m, 28H), see Figure 3 .

[0041] Step 4: Add 1.023 mg (0.13 mmol, 1 eq) of DTH-dimer-400 and 0.977 mg (0.13 mmol, 1 eq) of tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TTPE) into 0.4 mL of DMSO. After completely dissolving the two compounds by ultrasound, drop the resulting mixed solution onto a glass plate to spread it completely. Then, place the glass plate in a constant temperature and humidity biochemical incubator for film-forming reaction. After 20 hours of reaction, take it out and control the solution to completely evaporate. Then, place the glass plate in deionized water to obtain a polymer fluorescent sensing film, named TTPE-DTH-400-G film.

[0042] The excitation emission spectrum of the obtained TTPE-DTH-400-G film is tested, and the results are shown in Figure 4 .Depend on Figure 4 The excitation emission spectrum in the figure shows that the excitation wavelength of the TTPE-DTH-400-G film is 440nm and the emission wavelength is 525nm. The film was purged with DCP vapor, and the changes in the emission spectrum of the film under 440nm excitation light were recorded. During the DCP vapor purge process, the emission intensity of the TTPE-DTH-400-G film changed significantly, and the emission intensity continued to decrease. The results are shown in Figure 5 .Depend on Figure 5 It can be seen that the TTPE-DTH-400-G film has an obvious response to DCP, and the DCP detection can be judged according to the fluorescence intensity at 525 nm.

[0043] The TTPE-DTH-400-G film was tested by field emission scanning electron microscope. The results are shown in Figure 6 .Depend on Figure 6 It can be seen that the surface of TTPE-DTH-400-G film is relatively smooth in macroscopic observation, and its microscopic structure observation shows that its surface has certain pores. The TTPE-DTH-400-G film was subjected to infrared testing, and the results are shown in Figure 7 .from Figure 7 It can be clearly observed that the 1500cm -1 3300cm -1 The NH bond stretching peaks around 1190cm-1 decreased in intensity after film formation, indicating that the relative content of -NH bonds in DTH-dimer-400-ester decreased. -1 The peak intensity of the CN bond stretching vibration at 1699cm also decreased, indicating that the CN bond stretching vibration of DTH-dimer-400-ester is restricted, which may be due to the restricted vibration after combining with TTPE. -1 The absorption peak at 1602 cm is the characteristic vibration absorption peak of carbonyl group. It has slightly moved in TTPE-DTH-400-G film. It is speculated that the aldehyde group in DTH-dimer-400-ester is converted into ketone after reaction with TTPE. -1 The strong absorption peak at 1213 cm -1 The absorption peak at is attributed to the C=N double bond generated by the reaction, proving that its relative content decreases after the formation of the TTPE-DTH-400-G film. The above infrared results show that DTH-dimer-400-ester and TTPE monomer undergo Schiff base reaction to polymerize and form an acylhydrazone bond. In addition, the surface element analysis of the TTPE-DTH-400-G film was performed by X-ray photoelectron spectroscopy (XPS), and the distribution of elements and functional groups on the surface of the TTPE-DTH-400-G film was obtained to further confirm whether the two monomers in the obtained film reacted to form an acylhydrazone bond. Figure 8 As shown in a, the XPS spectrum shows that there are almost no impurity peaks, judging that the surface of the film prepared by the gas-liquid interface method is very clean, and the TTPE-DTH-400-G film is mainly composed of three elements: C, N, and O. This result is consistent with the elemental composition of the two monomers. The C1s peak in the XPS spectrum of the TTPE-DTH-400-G film was split to obtain four single peaks (see Figure 8 b), it can be seen that the peak with a binding energy of 284.65 eV can be attributed to C=C, CC, the peak at 288.25 eV can be attributed to C=O in the acylhydrazone group, the peak at 285.25 eV can be attributed to C=N in the acylhydrazone group, and the peak at 286.45 eV can be attributed to CO in the PEG chain. The N1s peak in the XPS spectrum of the TTPE-DTH-400-G film was split to obtain two single peaks (see Figure 8c), it can be seen that the peak with a binding energy of 399.45 eV can be attributed to the C=N in the acylhydrazone group, and the peak of 400.05 eV can be attributed to the formation of the imine bond CN in the acylhydrazone bond. The O1s peak in the XPS spectrum of the TTPE-DTH-400-G film was split to obtain two single peaks (see Figure 8 d), it can be seen that the peak with a binding energy of 533.05 eV can be attributed to CO in the PEG chain, and the peak of 531.95 eV can be attributed to C=O in the acylhydrazone bond. Figure 8 By summarizing and analyzing the data in, it can be determined that DTH-dimer-400-ester and TTPE monomer condense through Schiff base reaction to form acylhydrazone bond, forming TTPE-DTH-400-G film.

[0044] Example 2

[0045] Application of the polymer fluorescent sensing film prepared in Example 1 to detect nerve agent sarin simulant

[0046] The TTPE-DTH-400-G film prepared in Example 1 was placed on a quartz substrate. Preliminary sensing tests showed that DCP could significantly reduce the fluorescence of the TTPE-DTH-400-G film at 525 nm. The sensing sensitivity test of the TTPE-DTH-400-G film showed that the TTPE-DTH-400-G film could detect the ppt-level sarin simulant DCP (see Fig. 9 ), indicating that the polymer fluorescent sensing film is expected to be used in the detection of ultra-low concentration nerve agent sarin.

[0047] The detection of DCP by the TTPE-DTH-400-G film is significantly different from that of some common VOCs gases (acetone, dichloromethane, 1,4-dioxane, ethyl acetate, methanol, acetonitrile, chloroform, tetrahydrofuran, toluene, benzaldehyde, ethanol, triethylamine, ammonia, acetic acid, formic acid, and hydrochloric acid). Fig.10 ), indicating that the obtained TTPE-DTH-400-G film has high sensitivity and responsiveness to the detection of DCP. The response intensity of the TTPE-DTH-400-G film to the common sarin detection interfering substance hydrogen chloride is much lower than that to DCP, achieving specific detection of the sarin simulant DCP.

[0048] In summary, the TTPE-DTH-400-G film of the present invention has good response speed, selectivity, and recoverability in the detection of the sarin simulant DCP, and the detection limit can be as low as 1ppt, which is lower than the detection limit of the self-supporting flexible film for the nerve agent sarin reported in previous studies, and is far lower than the concentration of 7ppb at which the nerve agent sarin poses a direct threat to human life and health, which is of great significance for the early detection of the nerve agent sarin.

Claims

1. A polymer fluorescent sensor film, characterized in that: The structural unit of the polymer is shown below:

2. A method for preparing the polymer fluorescent sensor film according to claim 1, characterized in that: The steps include: Step 1: Add PEG-400, p-toluenesulfonyl chloride and potassium hydroxide to dichloromethane, react at room temperature for 12 to 24 hours in a nitrogen atmosphere, quench the reaction with water after the reaction is completed, separate and purify to obtain compound 1 based on polyethylene glycol chain connection; Step 2: Compound 1, 2-hydroxyterephthalate and potassium carbonate are added to acetone, and the mixture is reacted at 60-80° C. for 48-60 hours in a nitrogen atmosphere. After the reaction is completed, the mixture is cooled to room temperature, separated and purified to obtain diterephthalate connected by a polyethylene glycol chain, which is recorded as DTH-dimer-400-ester; Step 3: Add DTH-dimer-400-ester and excess hydrazine hydrate into methanol, react at 70-80° C. in a nitrogen atmosphere for 5-6 days, cool to room temperature after the reaction is completed, separate and purify to obtain bis(terephthaloyl)hydrazide connected by polyethylene glycol chains, recorded as DTH-dimer-400; Step 4: Dissolve DTH-dimer-400 and tetrakis-(4-formyl-(1,1-biphenyl))ethylene in DMSO, and drip the resulting mixed solution onto a glass plate to spread it completely; then place the glass plate in a constant temperature and humidity biochemical incubator for film-forming reaction; take out the plate after reacting for 24 to 36 hours, and after the solution is completely evaporated, place the glass plate in deionized water to obtain the polymer fluorescent sensing film; 3. The method for preparing the polymer fluorescent sensor film according to claim 2, characterized in that: In step 1, the molar ratio of PEG-400, p-toluenesulfonyl chloride and potassium hydroxide is 1:2-2.5:3-4.

4. The method for preparing the polymer fluorescent sensor film according to claim 2, characterized in that: In step 2, the molar ratio of the compound 1, 2-hydroxyterephthalate and potassium carbonate is 1:2.8-3.5:4-4.

5.

5. The method for preparing the polymer fluorescent sensor film according to claim 2, characterized in that: In step 3, the molar ratio of the DTH-dimer-400-ester to the hydrazine hydrate is 1:50-80.

6. The method for preparing the polymer fluorescent sensor film according to claim 2, characterized in that: In step 4, the molar ratio of DTH-dimer-400 to tetrakis-(4-formyl-(1,1-biphenyl))ethylene is 1 to 1.5:

1.

7. Use of the polymer fluorescent sensor film according to claim 1 in detecting the nerve agent sarin simulant diethyl chlorophosphate.

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