Nanometer film based on azetidine hydrazide derivative and preparation method and fluorescence sensing application thereof

Abstract

The invention discloses a nano-film based on an azetidine hydrazide derivative and a preparation method and fluorescence sensing application thereof, and the nano-film is prepared by taking the azetidine hydrazide derivative and tetraformyl tetraphenylethylene as construction units through a dynamic confinement self-assembly reaction of a gas-liquid interface. By introducing azetidine into hydrazide, the molecular structure can be changed, the electronic configuration can be regulated and controlled, and meanwhile, the system is endowed with specific sensing recognition capability. The preparation method of the nano-film is simple and easy to implement and mild in condition, the size of the film can be accurately regulated and controlled by changing the size of the glass substrate, and convenience is provided for application of the nano-film in large-scale production. The nano-film not only has a flat and smooth surface and good flexibility and self-supporting capability, but also has excellent sensing performance of gaseous nerve poison simulants diethyl chlorophosphate (DCP) and thionyl chloride (SOCl2), shows fluorescence color change from dark to bright, and can realize field detection and distinguishing identification of DCP and SOCl2.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of gas phase sensing materials, and particularly relates to a nano-film prepared by a template-free gas-liquid interface self-assembly, and application of the nano-film in fluorescence sensing and detection of nerve agent simulants diethyl chlorophosphate (DCP) and thionyl chloride (SOCl2). BACKGROUND

[0002] Sensing technology plays an important role in modern industry, scientific research and daily life. Among them, optical sensing technology, as an important sensing method, is widely studied and applied. As a branch of optical sensing technology, fluorescence sensing technology is applied to the monitoring and detection of various chemical substances, biological molecules and physical quantities due to its high sensitivity to target substances and fast response capability.

[0003] In the field of fluorescence sensing technology, film-based fluorescence sensors (FSSs) have become one of the research hotspots due to their potential advantages such as device miniaturization, easy integration, and suitability for realizing portable and online monitoring. An ideal film-based fluorescence sensor should have high sensitivity, high selectivity, excellent stability and reversibility (3S+1R), and fast response speed. To achieve the above performance, the existing technology mainly focuses on the design and preparation of sensing film materials (such as the design of sensing fluorophores and the engineering design of active layer structure) and the optimization of sensor device structure. However, despite some progress has been made in the preparation and application of film-based fluorescence sensors, the existing technology still faces many challenges and limitations. For example, in the field of detecting nerve agent simulants and other hazardous chemicals using film-based fluorescence sensors, current film-based fluorescence sensors still have some problems, such as limited response and recovery speed, which makes it difficult to meet the real-time monitoring needs of transient or rapidly changing signals; weak anti-interference ability, easily affected by other substances in complex environments, affecting detection accuracy; and most of them are quenching type responses. For example, the inventors previously prepared a polymeric nano-film based on polyethylene glycol chains to detect DCP (CN 119192509 A), and a fluorescence nano-film based on tetraphenyl ethene derivatives to detect SOCl2 (ACS Appl. Mater. Interfaces 2024, 16, 62944-62951), both of which are quenching type responses and are easily disturbed in complex environments, which may produce false positive signals. These problems significantly restrict the wide application and performance of film-based fluorescence sensors in complex scenarios. Therefore, the existing technology still needs a film-based fluorescence sensing technology or sensing unit that can overcome the above limitations, especially in terms of anti-interference, sensitivity, and response speed. SUMMARY

[0004] The present application aims to provide a nano-film with fast response speed, high sensitivity and strong anti-interference.

[0005] To achieve the above-mentioned purpose, the present application provides a nano-film based on azetidine hydrazide derivative, which comprises a repeating structural unit formed by covalent connection of azetidine hydrazide derivative and tetraaldehyde tetraphenylethylene through acylhydrazone bond, and the structural unit is as shown below:

[0006]

[0007] Further, the present application provides a method for preparing the above-mentioned nano-film by template-free self-assembly, comprising the following steps:

[0008] Step 1, preparation of azetidine hydrazide derivative monomer

[0009] Under a nitrogen atmosphere, 2,5-dibromo diethyl phthalate, methanesulfonic acid (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl) palladium (II), 2-dicyclohexylphosphine-2',6'-diisopropoxy-1,1'-biphenyl and cesium carbonate are added to dry 1,4-dioxane, and azetidine is added under stirring, and the reaction is stirred at 100-120℃ for 24-48h, and then separated and purified to obtain 2,5-bis(azetidin-1-yl) diethyl terephthalate (DAz); then DAz is reacted with hydrazine hydrate in methanol at 60-70℃ for 36-72h, and then separated and purified to obtain 2,5-bis(azetidin-1-yl) terephthalic dihydrazide (DATH), i.e. azetidine-based hydrazide derivative monomer. The reaction equation is as follows:

[0010]

[0011] Step 2, preparation of precursor solution

[0012] The azetidine-based hydrazide derivative monomer prepared in step 1 and tetraaldehyde tetraphenylethylene (TFPE) are added to dimethyl sulfoxide (DMSO) according to a molar ratio of 2:1-3:1, and after ultrasonic treatment at 40-90Hz for 2-10min, the solid phase is repeatedly heated and shaken until complete dissolution, and then filtered through a 0.45μm organic filter membrane to remove small particles, and then acetic acid is added as a catalyst, and the mixture is uniformly mixed to obtain a precursor solution.

[0013] Step 3, dynamic assembly of nano-film at gas-liquid interface

[0014] The precursor solution of step 2 is dropped on the pre-cleaned glass sheet to uniformly spread the precursor solution, and then the DATH and TFPE are allowed to undergo condensation reaction of acylhydrazone bond in a constant temperature and humidity environment with a temperature of 20-30℃ and a relative humidity of 55%-70% for 4-8 hours, and a nano film is formed at the gas-liquid interface and cleaned with deionized water.

[0015]

[0016] In the above step 1, the molar ratio of the 2,5-dibromophthalic acid diethyl ester, methylsulfonic acid (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl) (2-amino-1,1'-biphenyl-2-yl) palladium (II), 2-dicyclohexylphosphine-2',6'-diisopropoxy-1,1'-biphenyl, cesium carbonate, and azetidine is preferably 1:0.1-0.2:0.1-0.2:2-4:4-6.

[0017] In the above step 1, the molar ratio of the 2,5-dibromophthalic acid diethyl ester, methylsulfonic acid (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl) (2-amino-1,1'-biphenyl-2-yl) palladium (II), 2-dicyclohexylphosphine-2',6'-diisopropoxy-1,1'-biphenyl, cesium carbonate, and azetidine is preferably 1:0.1-0.2:0.1-0.2:2-4:4-6.

[0018] In the above step 2, the molar ratio of the azetidine-based hydrazine derivative monomer and tetraaldehyde tetraphenylethylene is preferably 2-3:1, the concentration of the precursor solution tetraaldehyde tetraphenylethylene is 2-15 mmol / L, and the volume fraction of acetic acid is 0.3%-1.0%.

[0019] In the above step 2, the total concentration of the azetidine-based hydrazine derivative monomer and tetraaldehyde tetraphenylethylene in the precursor solution is 2.5-15 mg / mL.

[0020] Further, in the above step 2, the total concentration of the azetidine-based hydrazine derivative monomer and tetraaldehyde tetraphenylethylene in the precursor solution is preferably 5-10 mg / mL.

[0021] The application also provides the use of the above nano film in fluorescence sensing detection of nerve agent analog DCP.

[0022] The application also provides the use of the above nano film in fluorescence sensing detection and identification of SOCl2.

[0023] The application has the following beneficial effects:

[0024] 1. The application takes DATH and TFPE as core units, and prepares a nanofilm through dynamic self-assembly at an air / DMSO interface. The TFPE unit contains multiple reaction groups, can react with DATH to crosslink to form a nanofilm, and its non-planar structure can enhance the porosity of the nanofilm at the molecular level, promote the contact response between the nanofilm and the analyte molecules; the DATH unit has a relatively stable rigid structure, and the hydrazide group acts as a reaction binding site.

[0025] 2. The application adopts an air / DMSO gas-liquid interface self-assembly strategy, and uses the acylhydrazone bond in the reversible dynamic covalent bond as a crosslinking method to prepare a nanofilm. The obtained nanofilm has excellent stability, good uniformity and repeatability and no matrix effect. Through the self-aggregation behavior of the acylhydrazone bond at the interface, the use of a complex template is avoided, the macroscopic morphology of the nanofilm can be controlled by regulating the size and shape of the substrate, and the thickness of the nanofilm can also be controlled by regulating the drop coating amount of the precursor solution. Therefore, the preparation method of the application is simple in operation, mild in reaction conditions and does not require complex equipment, and the process is controllable, which provides convenience for large-scale production application.

[0026] 3. The nanofilm prepared by the application is smooth and uniform, and has high mechanical strength, and is an excellent nanofilm-based sensing material. The prepared nanofilm is washed clean, and a thin film sensing unit is formed by being loaded on a quartz sheet, which has excellent "Turn On" response to nerve agent simulants DCP and SOCl2. Compared with the quenching response, it has lower background interference, high tolerance to non-specific interference and easier visual identification from dark to bright, and is suitable for the field detection of DCP and SOCl2, and can realize the detection and differential identification of DCP and SOCl2. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 1 is an optical picture of the nanofilm prepared in Example 1. Wherein (a) is an optical photo of the nanofilm under a daylight lamp; (b) is an optical photo of a sharp object exerting force on the surface of the nanofilm; (c) is an optical photo of the nanofilm self-supporting on a iron ring.

[0028] Figure 2 Figure 2 is a scanning electron microscope photo of the nanofilm prepared in Example 1. Wherein (a) is a photo of the nanofilm attached to a silicon wafer; (b) is an energy dispersive X-ray spectroscopy mapping photo of the nanofilm.

[0029] Figure 3 Figure 3 is an infrared spectrum of the nanofilm prepared in Example 1.

[0030] Figure 4X-ray photoelectron spectroscopy of the nanofilm prepared in Example 1, including full spectrum, C spectrum, N spectrum, and O spectrum.

[0031] Figure 5 Atomic force microscopy images of the nanofilm prepared in Example 1. (a) is the surface topography of the nanofilm; (b) is the cross-section of the nanofilm; (c) is the thickness information of the nanofilm.

[0032] Figure 6 Atomic force microscopy images of the nanofilm prepared in Example 2. (a) is the surface topography of the nanofilm; (b) is the cross-section of the nanofilm; (c) is the thickness information of the nanofilm.

[0033] Figure 7 Atomic force microscopy images of the nanofilm prepared in Example 3. (a) is the surface topography of the nanofilm; (b) is the cross-section of the nanofilm; (c) is the thickness information of the nanofilm.

[0034] Figure 8 Atomic force microscopy images of the nanofilm prepared in Example 4. (a) is the surface topography of the nanofilm; (b) is the cross-section of the nanofilm; (c) is the thickness information of the nanofilm.

[0035] Figure 9 Optical images of the nanofilm prepared in Example 5 supported on filter paper.

[0036] Figure 10 Optical images of the nanofilm prepared in Example 6 supported on filter paper.

[0037] Figure 11 Fluorescence emission spectra of the nanofilm prepared in Example 1 for different analyte saturated vapors (a) and visualized images before and after DCP, hydrochloric acid (HC1), trifluoroacetic acid (TFA), and SOCl2 responses (b).

[0038] Figure 12 Kinetic curve of the nanofilm prepared in Example 1 for gaseous DCP (sensor monitoring wavelength is 550 nm).

[0039] Figure 13 Response data of the nanofilm prepared in Example 1 for different concentrations of DCP, and the inset is the linear relationship between the response signal of the nanofilm for different concentrations of DCP and the concentration of DCP.

[0040] Figure 14 Comparison of the response signals of the nanofilm prepared in Example 1 for DCP and potential interferents, and the inset is the comparison of the response signals of the interferents in the saturated state with more obvious interference.

[0041] Figure 15 is a repeatability test of 40 consecutive responses of the nanofilm prepared in Example 1 to 1.32 ppm DCP.

[0042] Figure 16 is a response kinetics curve of the nanofilm prepared in Example 1 to gaseous SOCl2(the sensor monitoring wavelength is 620 nm).

[0043] Figure 17 is response data of the nanofilm prepared in Example 1 to SOCl2of different concentrations, and the inset is a linear relationship between the response signal of the nanofilm to SOCl2of different concentrations and the concentration of SOCl2.

[0044] Figure 18 is a response signal comparison of the nanofilm prepared in Example 1 to SOCl2and potential interferents, and the inset is a response signal comparison of the interferents in a saturated state with more obvious interference.

[0045] Figure 19 is a repeatability test of 40 consecutive responses of the nanofilm prepared in Example 1 to 1.31 ppb SOCl2. DETAILED DESCRIPTION

[0046] In order to make the person skilled in the art better understand the present application, the technical solutions of the present application will be described clearly and completely in combination with the embodiments and the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0047] Example 1

[0048] Step 1, preparation of azetidine hydrazide derivative monomer

[0049] Under nitrogen atmosphere, 5.0 g (13.16 mmol) of diethyl 2,5-dibromophthalate, 1.1 g (1.32 mmol) of (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate, 0.6 g (1.32 mmol) of 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl, and 12.9 g (39.48 mmol) of cesium carbonate were added to a flask, followed by the addition of 50 mL of dry 1,4-dioxane, and 4.5 mL (65.80 mmol) of azetidine was added under stirring, and the reaction was stirred at 110°C for 36 h. After the reaction was completed, the product was separated and purified to obtain diethyl 2,5-bis(azetidin-1-yl)terephthalate (DAz). Then, 0.1 g (0.30 mmol) of DAz and 0.2 mL (4.52 mmol) of hydrazine hydrate were added to 8 mL of methanol, and the reaction was stirred at 67°C for 48 h. After the reaction was completed, the product was separated and purified to obtain 2,5-bis(azetidin-1-yl)terephthalohydrazide (DATH), which is an azetidine-based hydrazide derivative monomer. The reaction equation thereof is as follows:

[0050]

[0051] The NMR and mass spectrometry data of the above DATH are as follows: 1 H NMR (600 MHz, DMSO-d6): δ 9.32 (s, 2H), 6.31 (d, J = 25.0 Hz, 2H), 4.39 (s, 4H), 3.75-3.58 (m, 8H), 2.23-2.10 (m, 4H); MS (m / z) (C 14 H 20 N6O2): Theoretical value 304.16, measured value 304.15.

[0052] Step 2, preparation of a precursor solution

[0053] After 0.58 mg (1.90 x 10 -3 mmol) of DATH and 0.42 mg (9.50 x 10 -4 mmol) of TFPE were uniformly mixed in a 1.5 mL dropper, 200 μL of DMSO was added, and the mixture was ultrasonicated at 80 Hz for 3 min. Then, the mixture was heated and shaken alternately at 50-60°C until DATH and TFPE were completely dissolved, and then the mixture was cooled to room temperature. The mixture was filtered through a 0.45 μm organic filter membrane to remove fine particles, 1 μL of acetic acid was added to the filtrate, and the mixture was uniformly shaken to obtain a precursor solution.

[0054] Step 3, dynamic assembly of a nanofilm at a gas-liquid interface

[0055] A square glass slide with a side length of 18 mm was subjected to surface plasma cleaning for 2 minutes to ensure that the precursor solution could be uniformly spread on the glass slide surface. Then, 100 μL of the precursor solution from step 2 was drop-coated onto the glass slide, ensuring uniform spread. The slide was then transferred to a constant temperature and humidity chamber and subjected to an acylhydrazone condensation reaction at 25 °C and 65% RH for 4 hours, resulting in the self-assembly of a nanofilm at the gas-liquid interface. After the reaction was complete, a complete, uniform, and transparent nanofilm was observed on the glass slide surface. This nanofilm was then transferred to a petri dish containing deionized water. The nanofilm detached from the glass slide and floated on the water surface. The film was repeatedly washed with deionized water to remove solid particles, thus obtaining the nanofilm.

[0056] from Figure 1 As seen in the optical photograph (a), the nanofilm appears pale yellow and transparent under fluorescent light, with a smooth and uniform surface. When pressure is applied to the surface of the nanofilm with a sharp object (tweezers), significant deformation is observed, but the film does not rupture. Figure 1 (b) indicates that the nanofilm possesses good flexibility. Further examination using a hollow iron ring to retrieve the film revealed that the nanofilm can self-support in air. Figure 1 (c) indicates that it has good mechanical toughness.

[0057] The surface morphology of the nanofilm was characterized using field emission scanning electron microscopy, and the results are as follows: Figure 2 As shown in (a), the surface of the nanofilm in the microscopic state is smooth and flat, without defects. Figure 2 (b) is the EDS-Mapping elemental mapping spectrum, which shows that the main elements C, N and O on the surface of the nanofilm are uniformly distributed.

[0058] The composition and structure of the nanofilm were characterized using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Figure 3 The infrared spectrum clearly shows that the characteristic absorption peak signals of the monomers changed significantly before and after the reaction, such as the 3500 cm⁻¹ peak in DATH after the reaction was complete. -1 and 3300cm -1 The disappearance of the stretching vibration peaks of the -NH- and -NH2 groups and the 1690 cm⁻¹ -1 The broadening of the -CH=O peak at 1600 cm⁻¹ -1 The new sharp absorption peak observed is attributed to -C=N-. This phenomenon indicates that an acylhydrazone condensation reaction occurred between the acylhydrazine group and the aldehyde group. Figure 4The XPS spectra revealed that the main constituent elements of the nanofilm were C, N, and O. Subsequent fine-tuning of the chemical bond composition was performed. The results were consistent with those obtained from the infrared spectroscopy analysis, further confirming the formation of acylhydrazone bonds during the nanofilm formation process from different perspectives.

[0059] Example 2

[0060] Step 1: Preparation of aza-butane hydrazine derivative monomers

[0061] This step is the same as step 1 in Example 1.

[0062] Step 2: Preparation of precursor solution

[0063] 0.29mg (9.45×10) -4 0.21 mg (4.72 × 10 mmol) DATH and 0.21 mg (4.72 × 10 mmol) DATH -4 After mixing 1 mmol TFPE in a 1.5 mL spotting tube, add 200 μL DMSO, sonicate at 80 Hz for 3 min, then heat at 50–60 °C with alternating shaking to completely dissolve DATH and TFPE. Then cool to room temperature, filter through a 0.45 μm organic filter membrane to remove small particles, add 1 μL acetic acid to the filtrate, shake well to obtain the precursor solution.

[0064] Step 3: Dynamic assembly of nanofilms at the gas-liquid interface

[0065] This step is the same as step 3 in Example 1.

[0066] Example 3

[0067] Step 1: Preparation of aza-butane hydrazine derivative monomers

[0068] This step is the same as step 1 in Example 1.

[0069] Step 2: Preparation of precursor solution

[0070] 1.16mg (3.78×10) -3 0.84 mg (1.89 × 10 mmol) DATH and 0.84 mg (1.89 × 10 mmol) DATH -3 After mixing 1 mmol TFPE in a 1.5 mL spotting tube, add 200 μL DMSO, sonicate at 80 Hz for 3 min, then heat at 50–60 °C with alternating shaking to completely dissolve DATH and TFPE. Then cool to room temperature, filter through a 0.45 μm organic filter membrane to remove small particles, add 1 μL acetic acid to the filtrate, shake well to obtain the precursor solution.

[0071] Step 3: Dynamic assembly of nanofilms at the gas-liquid interface

[0072] This step is the same as step 3 in Example 1.

[0073] Example 4

[0074] Step 1: Preparation of aza-butane hydrazine derivative monomers

[0075] This step is the same as step 1 in Example 1.

[0076] Step 2: Preparation of precursor solution

[0077] 1.73mg (5.70×10) -3 1.27 mg (2.85 × 10 mmol) DATH and 1.27 mg (2.85 × 10 mmol) DATH -3 After mixing 1 mmol TFPE in a 1.5 mL spotting tube, add 200 μL DMSO, sonicate at 80 Hz for 3 min, then heat at 50–60 °C with alternating shaking to completely dissolve DATH and TFPE. Then cool to room temperature, filter through a 0.45 μm organic filter membrane to remove small particles, add 1 μL acetic acid to the filtrate, shake well to obtain the precursor solution.

[0078] Step 3: Dynamic assembly of nanofilms at the gas-liquid interface

[0079] This step is the same as step 3 in Example 1.

[0080] Figures 5-8 The images show the surface roughness and cross-sectional thickness correlation spectra of the nanofilms prepared in Examples 1-4 above, characterized by AFM. Experimental results demonstrate that the film thickness can be controlled from 70 nm to 395 nm by adjusting the total concentration of DATH and TFPE in the precursor solution. Furthermore, the nanofilm surface remains smooth and uniform throughout the thickness range, fully confirming the precision and controllability of the nanofilm preparation process.

[0081] Example 5

[0082] Step 1: Preparation of aza-butane hydrazine derivative monomers

[0083] This step is the same as step 1 in Example 1.

[0084] Step 2: Preparation of precursor solution

[0085] 4.61mg (1.52×10 -2 3.39 mg (7.63 × 10 mmol) DATH and 3.39 mg (7.63 × 10 mmol) DATH -3After mixing 1 mmol TFPE in a 5.0 mL spotting tube, add 1600 μL DMSO, sonicate at 80 Hz for 3 min, then heat at 50–60 °C with alternating shaking to completely dissolve DATH and TFPE. Then cool to room temperature and filter through a 0.45 μm organic filter membrane to remove small particles. Add 8 μL acetic acid to the filtrate, shake well to obtain the precursor solution.

[0086] Step 3: Dynamic assembly of nanofilms at the gas-liquid interface

[0087] A circular glass slide with a diameter of 8 cm was subjected to surface plasma cleaning for 2 minutes to ensure that the precursor solution could be uniformly spread on the glass slide surface. Then, 1600 μL of the precursor solution from step 2 was drop-coated onto the glass slide, ensuring uniform spread. The slide was then transferred to a constant temperature and humidity chamber and subjected to an acylhydrazone condensation reaction at 25°C and 65% RH for 4 hours, resulting in the self-assembly of a nanofilm at the gas-liquid interface. After the reaction was complete, a complete, uniform, and transparent nanofilm was observed on the glass slide surface. This nanofilm was then transferred to a suitably sized container, and water was slowly poured into the container. The nanofilm detached from the glass slide and floated on the water surface. The film was repeatedly washed with deionized water to remove solid particles, thus obtaining the nanofilm. It was then loaded onto filter paper and dried.

[0088] Example 6

[0089] Step 1: Preparation of aza-butane hydrazine derivative monomers

[0090] This step is the same as step 1 in Example 1.

[0091] Step 2: Preparation of precursor solution

[0092] 9.24mg (3.04×10) -2 6.76 mg (1.52 × 10 mmol) DATH and 6.76 mg (1.52 × 10 mmol) DATH -2 After mixing 1 mmol TFPE in a 5.0 mL spotting tube, add 3200 μL DMSO, sonicate at 80 Hz for 3 min, then heat at 50–60 °C with alternating shaking to completely dissolve DATH and TFPE. Then cool to room temperature and filter through a 0.45 μm organic filter membrane to remove small particles. Add 16 μL acetic acid to the filtrate, shake well to obtain the precursor solution.

[0093] Step 3: Dynamic assembly of nanofilms at the gas-liquid interface

[0094] A 10 cm square glass slide was surface plasma cleaned for 2 min to ensure the precursor solution could spread evenly on the glass surface. Then 3200 μL of the precursor solution in step 2 was dropped on the glass slide to make the precursor solution spread evenly, and then it was transferred to a constant temperature and humidity chamber to perform the acylhydrazone bond condensation reaction at a temperature of 25 °C and a relative humidity of 65% RH for 4 h to form a nanofilm by self-assembly at the gas-liquid interface. The other steps of this step were the same as those of Example 5.

[0095] As shown in Figure 9 , 10 , the size and shape of the nanofilm can be controlled by controlling the size and shape of the glass substrate in Examples 5 and 6.

[0096] Example 7

[0097] Application of the nanofilm prepared in Example 1 in sensing and detecting gaseous DCP and SOCl2

[0098] The nanofilm prepared in Example 1 and its response to saturated vapors of different analytes were studied by a fluorescence spectrometer, as shown in Figure 11 (a). The initial film had no fluorescence, but after the addition of DCP vapor, the film showed a significant emission peak at 530 nm, while after the addition of hydrochloric acid (HCl), trifluoroacetic acid (TFA) and SOCl2 vapor, the optimal emission was at 620 nm and the fluorescence could be restored to the initial intensity by the addition of NH3; there was no obvious change after the addition of acetic acid (HAc) and trifluoromethanesulfonic acid (TfOH). Figure 11 The visualized photos of (b) further confirmed that DCP, HCl, TFA and SOCl2 vapor could cause the fluorescence of the nanofilm to change from dark to light, thereby realizing a "Turn On" response. The above data show that the nanofilm is expected to realize rapid detection of gaseous DCP, HCl, TFA and SOCl2.

[0099] The nanofilm after washing in step 2 of Example 1 was fished with a 12 mm diameter high-transmittance quartz glass disc, and after natural air drying, a thin film-based sensing unit for sensing test was obtained. Then it was integrated into a sensing platform, and the excitation wavelength and detection wavelength range of the sensor were adjusted. DCP vapor or SOCl2 vapor injected into a gas bag was connected to the sensing platform as an analyte, and in order to ensure that the sensing unit could successfully realize accurate signal collection in a stable and constant environment, NH3 was alternately introduced into the sensing unit as a signal recovery medium to maintain the normal working state of the sensing unit, thereby realizing real-time detection of the analyte multiple times.

[0100] 1. Sensing test of gaseous DCP (monitoring wavelength 550 nm)

[0101] Figure 12 is the response kinetics curve of the nanometer film to DCP, from which it can be observed that the fluorescence intensity signal changes rapidly at the moment of DCP vapor being introduced, and returns to the initial signal intensity within 2s after alternating NH3 being introduced, indicating that the nanometer film has a fast response speed to DCP vapor, and is expected to realize real-time online detection of DCP. Considering the subsequent continuous testing of high-concentration DCP vapor, the sampling time is finally determined to be 2s, and the NH3 introduction time is determined to be 4s.

[0102] Subsequently, in order to further explore the internal relationship between the fluorescence intensity signal change and the DCP concentration, the response of the nanometer film to DCP vapor of different concentrations was tested, and the results are shown in Figure 13 The nanometer film has a low detection limit of 0.52ppm, and within the concentration range of 0.52ppm to 8.8ppm, the fluorescence intensity signal change and the DCP concentration show good linear correlation.

[0103] In addition, the application also systematically evaluates the specific response ability of the obtained nanometer film to DCP vapor. Some common potential interferents such as HCl, TFA and SOCl2 vapor are introduced into the sensing platform as analytes, and the concentration is saturated gas, and the relevant signal is collected under the condition that the remaining test conditions are kept unchanged, and the test results are shown in Figure 14 It can be seen from the figure that the nanometer film can realize the identification of DCP, HCl, TFA and SOCl2 by the significant difference of the response kinetics curve, as shown in the inserted figure, which proves that the nanometer film of the application has excellent selectivity and anti-interference ability to DCP in a complex gas phase environment.

[0104] Reusability is also an important aspect of performance evaluation of sensing materials, therefore, 1.32ppm DCP vapor is selected for 40 continuous response cycle tests, as shown in Figure 15 The change of the fluorescence intensity signal is small during the test, indicating that the nanometer film has good reusability in the gaseous DCP test.

[0105] 2, sensing test of gaseous SOCl2 (monitoring wavelength is 620nm)

[0106] Figure 16 is the response kinetics curve of the nanometer film to SOCl2, from which it can be observed that the fluorescence intensity signal changes rapidly at the moment of SOCl2 vapor being introduced, and returns to the initial signal intensity within 4s after alternating NH3 being introduced, indicating that the nanometer film has a fast response speed to SOCl2 vapor, and is expected to realize real-time online detection of SOCl2. Considering the subsequent continuous testing of high-concentration SOCl2 vapor, the sampling time is finally determined to be 3s, and the NH3 introduction time is determined to be 4s.

[0107] In order to further explore the internal relationship between the change of fluorescence intensity signal and the concentration of SOCl2, the response of the nanofilm to SOCl2 vapor with different concentrations was tested, and the results are shown in Figure 17 It can be observed from the figure that the nanofilm has a low detection limit of 1.31 ppt, and the change of fluorescence intensity signal and the concentration of SOCl2 shows good linear correlation in the concentration range of 1.31 ppt to 131.30 ppb.

[0108] In addition, the specific response ability of the obtained nanofilm to SOCl2 vapor was also systematically evaluated. Some common potential interferents such as HCl, TFA and DCP vapor were introduced into the sensing platform as analytes, and the concentration was saturated gas. The related signals were collected under the condition that the remaining test conditions were kept consistent, and the test results are shown in Figure 18 It can be seen from the figure that the nanofilm can realize the identification and recognition of DCP, HCl, TFA and SOCl2 by the significant difference in response kinetics, as shown in the inserted figure. It is proved that the nanofilm of the present application has excellent selectivity and anti-interference ability to SOCl2 in complex gas phase environment.

[0109] Further, 1.31 ppb of SOCl2 vapor was selected for 40 times of continuous response cycle test, as shown in Figure 19 The change of fluorescence intensity signal in this test process is very small, indicating that the nanofilm has good reusability in the test of SOCl2 vapor.

[0110] In summary, the nanofilm prepared by the present application uses azetidine hydrazide derivative and tetraaldehyde-based tetraphenylethylene as building blocks, and is prepared by using the dynamic self-assembly strategy of air / DMSO interface. The obtained nanofilm has smooth surface and certain mechanical toughness. At the same time, the size and shape of the nanofilm can be controlled by changing the size and shape of the glass substrate. The nanofilm shows excellent "TurnOn" response to gas phase DCP and SOCl2, has high sensitivity, high selectivity and good repeatability. Therefore, the nanofilm of the present application is suitable for the field detection of DCP and SOCl2, and can realize the detection and identification of DCP and SOCl2.

[0111] The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A nanofilm based on an azetidine hydrazide derivative, characterized in that: The nanofilm comprises repeating structural units formed by covalent linkage of azetidine hydrazide derivative and tetraaldehyde-based tetraphenyl ethylene via acylhydrazone bond, which is shown as follows:

2. A method for template-free self-assembly of the nanofilms of claim 1, characterized by: The method comprises the following steps: Step 1, preparation of azetidine hydrazide derivative monomer Under nitrogen atmosphere, 2,5-dibromo phthalate diethyl ester, methanesulfonic acid (2-dicyclohexyl phosphino-2',6'-diisopropoxy-1,1'-biphenyl) (2-amino-1,1'-biphenyl-2-yl) palladium (II), 2-dicyclohexyl phosphine-2',6'-diisopropoxy-1,1'-biphenyl, cesium carbonate and azetidine are added into dry 1,4-dioxane, and stirred under nitrogen atmosphere, and then stirred at 100-120℃ for 24-48h, and then separated and purified to obtain 2,5-di(azetidin-1-yl) terephthalate diethyl ester; then 2,5-di(azetidin-1-yl) terephthalate diethyl ester and hydrazine hydrate are stirred in methanol at 60-70℃ for 36-72h, and then separated and purified to obtain 2,5-bis(azetidin-1-yl) terephthalic dihydrazide, i.e. azetidine-based hydrazide derivative monomer; Step 2, preparation of precursor solution The azetidine-based hydrazide derivative monomer and tetraaldehyde-based tetraphenyl ethylene prepared in step 1 are completely dissolved in dimethyl sulfoxide, and then acetic acid is added, and then mixed uniformly to obtain the precursor solution; Step 3, dynamic assembly of nanofilm at gas-liquid interface The precursor solution of step 2 is dropped on a pre-cleaned glass sheet, and the precursor solution is uniformly spread, and then acylhydrazone bond condensation reaction is carried out in a constant temperature and humidity environment with temperature of 20-30℃ and relative humidity of 55%-70% for 4-8h, and then a nanofilm is formed at the gas-liquid interface, and then washed with deionized water.

3. The template-free self-assembly method for preparing the nanofilm of claim 1 according to claim 2, characterized in that: In step 1, the molar ratio of 2,5-dibromo phthalate diethyl ester, methanesulfonic acid (2-dicyclohexyl phosphino-2',6'-diisopropoxy-1,1'-biphenyl) (2-amino-1,1'-biphenyl-2-yl) palladium (II), 2-dicyclohexyl phosphine-2',6'-diisopropoxy-1,1'-biphenyl, cesium carbonate and azetidine is 1:0.1-0.2:0.1-0.2:2-4:4-6.

4. The template-free self-assembly method for preparing the nanofilm of claim 1 according to claim 2, characterized in that: In step 1, the molar ratio of 2,5-di(azetidin-1-yl) terephthalate diethyl ester and hydrazine hydrate is 1:15-20.

5. The template-free self-assembly method for preparing the nanofilm of claim 1 according to claim 2, wherein: In step 2, the molar ratio of azetidine-based hydrazide derivative monomer and tetraaldehyde-based tetraphenyl ethylene is 2-3:1, the concentration of tetraaldehyde-based tetraphenyl ethylene in the precursor solution is 2-15mmol / L, and the volume fraction of acetic acid is 0.3%-1.0%.

6. The template-free self-assembly method of claim 5, wherein: In step 2, the total concentration of azetidine-based hydrazide derivative monomer and tetraaldehyde-based tetraphenyl ethylene in the precursor solution is 2.5-15mg / mL.

7. The template-free self-assembly method for fabricating the nanofilm of claim 1 according to claim 5, wherein: In step 2, the total concentration of azetidine-based hydrazide derivative monomer and tetraaldehyde-based tetraphenyl ethylene in the precursor solution is 5-10mg / mL.

8. The nanofilm of claim 1 is used for fluorescent sensing detection of nerve toxic agent mimic diethyl chlorophosphate.

9. Use of the nanofilm of claim 1 in fluorescent sensing detection and discrimination of recognition of thionyl chloride.

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