An ultra-sensitive dual-responsive fluorescent imine material, a preparation method thereof and application thereof in gaseous iodine fluorescence detection

Abstract

The application discloses a kind of super-sensitive dual-response fluorescence imine materials and its preparation method and application in gaseous iodine fluorescence detection, comprising: using anhydrous ethanol to soak sponge matrix, ultrasonic oscillation, wash impurities, dry.The dialdehyde monomer and azo type diamine monomer are added in organic solvent, oscillation after mixing, to obtain precursor solution;Crosslinking agent dissolved in organic solvent is added to precursor solution, ultrasonic constant volume, shake uniformly after standing, to obtain functional reagent;Sponge matrix is soaked in functional reagent, ultrasonic extrusion expels bubble in sponge matrix, and the sponge matrix soaked in functional reagent is dried, to obtain super-sensitive dual-response fluorescence imine material.The super-sensitive dual-response fluorescence imine material prepared by the application has super-sensitive dual-switch response for gaseous iodine fluorescence detection, can realize ultrafast early warning and quantitative detection to gaseous iodine leaked in nuclear energy utilization process, is portable and easy to operate, and has great commercial value.

Description

Technical Field

[0001] This invention belongs to the field of exhaust gas detection technology. More specifically, this invention relates to an ultrasensitive dual-response fluorescent imine material, its preparation method, and its application in gaseous iodine fluorescence detection. Background Technology

[0002] With technological advancements and policy support, the comprehensive utilization of nuclear energy is playing an increasingly important role in achieving energy security, reducing carbon emissions, and supporting sustainable development. However, radioactive iodine leakage remains a persistent environmental pollution problem during nuclear energy utilization. The main hazard of radioactive iodine lies in its high affinity for the thyroid gland, leading to radiation damage to thyroid cells and increasing the risk of thyroid cancer and other thyroid diseases. Internal exposure through inhalation and the food chain makes the hazards of radioactive iodine widespread and long-lasting. Therefore, timely and effective detection of leaked radioactive iodine is crucial.

[0003] Current off-site detection of leaked radioactive iodine largely relies on sampling and subsequent laboratory analysis. While this method offers high accuracy, it suffers from poor timeliness, failing to meet real-time monitoring requirements. In-situ detection, on the other hand, offers advantages such as rapid response and ease of operation, but generally suffers from insufficient sensitivity, poor selectivity, and weak environmental tolerance. Developing detection materials that combine high sensitivity, rapid response, and good stability has become a key breakthrough for achieving efficient detection of gaseous iodine. In recent years, sensing systems based on organic fluorescent molecules have attracted widespread attention because they can achieve selective recognition and signal output of specific analytes through molecular structure modulation. Azodiamine compounds, due to their unique chemical structure and physicochemical properties, are widely used in optics, dyes, pharmacology, and functional materials. They inherently possess azo bonds, which can produce fluorescence peaks at specific excitation wavelengths. When reacting with dialdehyde monomers under the action of crosslinking agents, they form Schiff base structures, simultaneously forming a larger π-conjugated system with the original azo bonds, naphthalene rings, and biphenyls of the azodiamine monomers, generating new fluorescence peaks at specific excitation wavelengths.

[0004] Among existing fluorescent detection gas technologies, CN117534660B discloses a H2O targeting mitochondria. + / ONOO -Dual-response organic fluorescent compounds belong to the field of organic fluorescent compound preparation and biodetection. However, for gaseous iodine, a typical inorganic pollutant in nuclear industry environments (such as nuclear reactor leaks and iodine chemical tail gas), there is a gap in the detection industry due to the lack of important target materials. CN106908430B discloses a quantitative fluorescence sensing material for CO2, involving a CO2 detection technology field. This material solves the industry pain points of traditional CO2 detection, such as susceptibility to interference from CO and moisture, complex operation, and poor field applicability, achieving rapid and accurate quantitative detection of CO2 concentration. However, the preparation process of this material has strict requirements for multiple parameters such as raw material concentration, temperature and humidity, and sealed environment. Deviation in any step may damage the crystal structure and sensing performance. At the same time, its crystal formation relies on the self-assembly of ligands and metal ions, which is highly uncontrollable, making it difficult to ensure the reproducibility and success rate of preparation. CN120248866A utilizes COF materials with a specific structure, which, after being ground into powder, can perform fluorescent detection of iodomethane in ethanol solutions. However, this fluorescence detection method limits its application scenarios, requiring liquid phase conditions or conditions necessitating liquid extraction. It cannot achieve in-situ gaseous sampling, making separation and recovery difficult, and is extremely inconvenient for rapid on-site detection. Even when COF fluorescent test paper is made for the detection of gaseous iodomethane, problems such as easy folding and damage during gaseous sampling persist. Furthermore, the relatively low porosity of the paper restricts gas diffusion, resulting in a slow response time and making it unsuitable for complex industrial environments. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] To achieve these and other advantages according to the present invention, the present invention provides an ultrasensitive dual-response fluorescent imine material, the structural formula of which is: Wherein, TPA is terephthalaldehyde, TREN is tris(2-aminoethyl)amine, and n≥1.

[0007] A method for preparing an ultrasensitive dual-response fluorescent imine material includes the following steps: S1. Cut the sponge matrix into cuboids with a length of 20-30 mm and a width and thickness of 5-15 mm to obtain an unmodified sponge matrix; soak the sponge matrix in anhydrous ethanol, vibrate it in an ultrasonic oscillator for 3-5 minutes, repeat 2-3 times, wash away impurities, and dry it for later use. S2. Add dialdehyde monomer and azo diamine monomer to an organic solvent, mix and then vibrate in an ultrasonic oscillator to mix them evenly to obtain a precursor solution; then add a crosslinking agent dissolved in an organic solvent to the precursor solution, so as to make up the volume by ultrasonication, and finally shake evenly and let stand to obtain a functionalized reagent. S3. Immerse the unmodified sponge matrix in a well-shaken functionalized reagent. Under conditions of 20~30℃, use ultrasound and compression to remove air bubbles from the sponge matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, dry the sponge matrix that has been immersed in the functionalized reagent at a certain temperature. During the drying process, turn the sponge matrix over every 3~10 minutes. After thorough drying, the ultrasensitive dual-response fluorescent imine material is obtained.

[0008] Preferably, in step S2, the crosslinking agent includes any one or a combination of two or more of spermidine, triethylenetetramine, diethylenetriamine, tri(2-aminoethyl)amine, and trimethylenetriamine.

[0009] Preferably, in S2, the azo diamine monomer is Congo red.

[0010] Preferably, in S2, the dialdehyde monomer includes any one or a combination of two or more of pyromellitic methyl methacrylate, terephthalic acid, adipaldehyde, biphenyl dimethyl methacrylate, and bipyridine dimethyl methacrylate.

[0011] Preferably, in S1 and S2, the organic solvent includes any one or a combination of two or more of dichloromethane, acetonitrile, ethanol, and ethyl acetate.

[0012] Preferably, in S2, the volume of the organic solution is 5-10 mL; the ratio of dialdehyde monomer, azodiamine monomer, crosslinking agent, and organic solvent is 1-10 mmol: 1-5 mmol: 1-5 mmol: 20-40 mL; the reaction time after adding the crosslinking agent and ultrasonically adjusting the volume is 15-30 min; and the reaction temperature is 20-30 °C.

[0013] Preferably, in step S3, the drying temperature is 70–80°C and the drying time is 2–5 hours.

[0014] An application of an ultrasensitive dual-response fluorescent imine material is disclosed. This material is used for the fluorescence detection of gaseous iodine. The specific method for fluorescence detection of gaseous iodine using the ultrasensitive dual-response fluorescent imine material includes: placing the ultrasensitive dual-response fluorescent imine material in a small beaker, then placing the small beaker in a wide-mouth bottle, heating it in an oven, taking samples at different times, and performing fluorescence detection. The fluorescence peak values ​​of the ultrasensitive dual-response fluorescent imine material after adsorption are compared with those before adsorption, thus achieving ultrafast early warning and quantitative detection of gaseous iodine using the ultrasensitive dual-response fluorescent imine material.

[0015] Preferably, the oven heating temperature is 50~100℃, and the gaseous iodine concentration in the wide-mouth bottle ranges from 1-1000mg / L.

[0016] The present invention has at least the following beneficial effects: 1. The present invention provides an ultrasensitive dual-response fluorescent imine material by in-situ polymerization of functionalized imine material on a porous matrix through solution processing. The material has good uniformity and structural stability and presents an overall porous bulk structure.

[0017] 2. The method for synthesizing ultrasensitive dual-response fluorescent imine materials provided by this invention is simple, mild, and environmentally friendly. It does not require the introduction of other external conditions and can achieve batch synthesis.

[0018] 3. The ultrasensitive dual-response fluorescent imine material exhibits an ultrasensitive dual-switch response for the fluorescence detection of gaseous iodine, enabling ultrafast early warning and quantitative detection of leaked gaseous iodine during nuclear energy utilization. It is portable, easy to operate, and has enormous commercial value.

[0019] Congo red, a classic azo dye, possesses a characteristic fluorescence emission peak. When Congo red undergoes a Schiff base condensation reaction with a dialdehyde monomer via a crosslinking agent to form a covalent network structure linked by imine bonds (-C=N-), the constructed ultrasensitive dual-response fluorescent imine material not only retains the original fluorescence properties of Congo red but also generates a second new fluorescence emission peak due to intramolecular charge transfer (ICT) effects or changes in aggregate structure. This synergistic response mechanism of dual fluorescence peaks endows the material with extremely high detection sensitivity for gaseous iodine and dual signal output capabilities. In practical applications, the material only needs to be exposed to trace amounts of gaseous iodine; its characteristic fluorescence peak at a longer wavelength (~670 nm) disappears rapidly. This "on-off" response can serve as a highly sensitive, visually perceptible early warning signal for iodine vapor leakage. Simultaneously, the intensity of another characteristic fluorescence peak at a shorter wavelength (~378 nm) gradually decreases with increasing iodine adsorption, thereby enabling quantitative analysis of gaseous iodine concentration. This dual-response synergistic detection strategy effectively improves the reliability of detection results and its resistance to environmental interference. Furthermore, the material can be directly placed in a gaseous environment for real-time, in-situ detection in the form of a solid film / bulk sponge without complex pretreatment. Its excellent mechanical stability, rapid response, and good reversibility demonstrate significant advantages in portable detection applications in scenarios such as nuclear facility safety monitoring, radioactive iodine leak early warning, and environmental emergency response.

[0020] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0022] Figure 1 Physical images of ultrasensitive dual-response fluorescent imine material samples prepared for this invention with concentrations of CR@MF100%, CR@MF50%, CR@MF20%, CR@MF10%, and CR@MF0%, respectively. Figure 2 This is a scanning electron microscope image of the ultrasensitive dual-response fluorescent imine material prepared in Example 1 of the present invention; Figure 3 This is a diagram of the adsorption of iodine vapor by the ultrasensitive dual-response fluorescent imine material in Application Example 1 of the present invention; Figure 4 The image shows fluorescence data of the ultrasensitive dual-response fluorescent imine material adsorbing gaseous iodine at different times in Application Example 3 of the present invention. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0024] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1 This embodiment provides a method for preparing an ultrasensitive dual-response fluorescent imine material, including the following steps: Step 1: Cut the original sponge into a cuboid with a length of 30mm and a width and thickness of 10mm to obtain an unmodified sponge matrix; immerse the sponge matrix in anhydrous ethanol, then place it in an ultrasonic oscillator and vibrate for 3 minutes. Repeat this process 3 times to wash away any impurities that may be present. Finally, dry it in an oven at a temperature of 75℃.

[0025] Step 3: Dissolve 1.5 mmol of terephthalaldehyde in 5 ml of ethanol to obtain an ethanol solution of terephthalaldehyde. Then add 0.75 mmol of Congo red to the ethanol solution of terephthalaldehyde and sonicate the solution for 5 min to promote the dissolution of Congo red, obtaining a mixed ethanol solution A of terephthalaldehyde and Congo red. Dissolve 0.5 mmol of tris(2-aminoethyl)amine in 5 ml of ethanol to obtain solution B. Mix solution A and solution B, sonicate for 5 min to allow solution A and solution B to react fully, then add ethanol solution to make up to 40 ml. Sonicate again for 3 min, then take out 20 ml, shake well at 25 °C, and let stand for 15 min to obtain the functionalized reagent.

[0026] Step 4: Place the sponge matrix from Step 1 into the functionalized reagent that was shaken evenly in Step 2, and let it stand at 25°C for 5 minutes. During this process, use ultrasound and compression to remove air bubbles from the matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, place the sponge matrix soaked in the functionalized reagent in an oven at 75°C to allow the ethanol solvent to evaporate. During the drying process, turn the sponge matrix over every 5 minutes. After 5 hours of thorough drying, a 100% concentration of ultrasensitive dual-response fluorescent imine material is obtained.

[0027] A photograph of the ultrasensitive dual-response fluorescent imine material prepared in this embodiment is shown below. Figure 1 As shown on the far left.

[0028] The microstructure of the ultrasensitive dual-response fluorescent imine material in the embodiments of the present invention was observed using a scanning electron microscope, such as... Figure 2 As shown, the functionalized reagents were successfully loaded onto the sponge matrix and distributed relatively evenly and densely on the sponge skeleton.

[0029] Application Example 1 An application of an ultrasensitive dual-response fluorescent imine material for the adsorption of gaseous iodine includes: The ultrasensitive dual-response fluorescent imine material prepared in Example 1 was weighed and placed in a small beaker. The beaker was then placed in a wide-mouthed bottle containing elemental iodine and heated in an oven at 75°C. The iodine vapor concentration was approximately 551 μM. Samples were taken and weighed at different times, and the adsorption performance of the material for iodine vapor was calculated using the gravimetric method. The adsorption capacity of the ultrasensitive dual-response fluorescent imine material at 75°C is as follows: Figure 3 As shown, the ultrasensitive dual-response fluorescent imine material prepared in Example 1 has an adsorption capacity of up to 2 g·g⁻¹ for iodine vapor. -1 . Figure 3 In the text, CR@MF0%, CR@MF10%, CR@MF20%, CR@MF50%, and CR@MF100% represent ultrasensitive dual-response fluorescent imine materials obtained by soaking in functionalized reagents at concentrations of 0%, 10%, 20%, 50%, and 100%, respectively. Figure 1 The images in the middle, from left to right, show actual products of CR@MF100%, CR@MF50%, CR@MF20%, CR@MF10%, and CR@MF0%.

[0030] Example 2 This embodiment provides a method for preparing an ultrasensitive dual-response fluorescent imine material, including the following steps: Step 1: Cut the original sponge into a cuboid with a length of 30mm and a width and thickness of 10mm to obtain an unmodified sponge matrix; immerse the sponge matrix in anhydrous ethanol, then place it in an ultrasonic oscillator and vibrate for 3 minutes. Repeat this process 3 times to wash away any impurities that may be present. Finally, dry it in an oven at a temperature of 75℃.

[0031] Step 3: Dissolve 1.5 mmol of terephthalaldehyde in 5 ml of ethanol solution, then add 0.75 mmol of Congo red to the terephthalaldehyde ethanol solution. Sonicate the solution for 5 min to promote the dissolution of Congo red, obtaining a mixed ethanol solution A. Dissolve 0.5 mmol of tris(2-aminoethyl)amine in 5 ml of ethanol solution to obtain solution B. Mix solution A and solution B, sonicate for 5 min to allow solution A and solution B to react fully, then add ethanol solution to make up to 40 ml. Sonicate again for 3 min, then take 2 ml and add ethanol solution to make up to 20 ml. Shake well at 25°C and let stand for 15 min to obtain the functionalized reagent.

[0032] Step 4: Place the sponge matrix from Step 1 into the functionalized reagent that was shaken evenly in Step 2, and let it stand at 25°C for 5 minutes. During this process, use ultrasound and compression to remove air bubbles from the sponge matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, place the sponge matrix soaked in the functionalized reagent in an oven at 75°C to allow the ethanol solvent to evaporate. During the drying process, turn the sponge matrix over every 5 minutes. After 5 hours of thorough drying, a 10% concentration of ultrasensitive dual-response fluorescent imine material is obtained.

[0033] Application Example 2 An application of an ultrasensitive dual-response fluorescent imine material for the fluorescent adsorption of gaseous iodine includes: The ultrasensitive dual-response fluorescent imine material prepared in Example 2 was weighed and placed in a small beaker. The small beaker was then placed in a wide-mouth bottle containing elemental iodine and heated in an oven at 75°C. The iodine vapor concentration was approximately 551 μM. Samples were taken and weighed at different times, and the adsorption performance of the material for iodine vapor was calculated using the gravimetric method.

[0034] Application Example 3 An application of an ultrasensitive dual-response fluorescent imine material for the fluorescence detection of gaseous iodine includes: The ultrasensitive dual-response fluorescent imine material prepared in Example 2 was placed in a small beaker, which was then placed in a wide-mouth bottle and heated in an oven at 75°C. Samples were taken at different times for fluorescence detection. The fluorescence intensity of the ultrasensitive dual-response fluorescent imine material after adsorbing iodine vapor for different times at 75°C was compared with that of the sample. Figure 4 As shown, at an excitation wavelength of 280 nm, the material exhibits two fluorescence peaks when no iodine is adsorbed, at 378 nm and 640 nm. However, when a very small amount of iodine vapor is adsorbed by the material, the fluorescence peak at 640 nm disappears immediately. The fluorescence intensity at 378 nm generally decreases with the amount of adsorbed iodine. This indicates that the ultrasensitive dual-response fluorescent imine material possesses an ultrasensitive dual-switch response for the fluorescence detection of gaseous iodine, enabling ultrafast early warning and quantitative detection of leaked gaseous iodine during nuclear energy utilization.

[0035] Example 3 This embodiment provides a method for preparing an ultrasensitive dual-response fluorescent imine material, including the following steps: Step 1: Cut the original sponge into a cuboid with a length of 30mm and a width and thickness of 10mm to obtain an unmodified sponge matrix; immerse the sponge matrix in anhydrous ethanol, then place it in an ultrasonic oscillator and vibrate for 3 minutes. Repeat this process 3 times to wash away any impurities that may be present. Finally, dry it in an oven at a temperature of 75℃.

[0036] Step 3: Dissolve 1.5 mmol of terephthalaldehyde in 5 ml of ethanol solution, then add 0.75 mmol of Congo red to the terephthalaldehyde ethanol solution. Sonicate the solution for 5 min to promote the dissolution of Congo red, obtaining a mixed ethanol solution A. Dissolve 0.5 mmol of tris(2-aminoethyl)amine in 5 ml of ethanol solution to obtain solution B. Mix solution A and solution B, sonicate for 5 min to allow solution A and solution B to react fully, then add ethanol solution to make up to 40 ml. Sonicate again for 3 min, then take 1 ml and add ethanol solution to make up to 20 ml. Shake well at 25°C and let stand for 15 min to obtain the functionalized reagent.

[0037] Step 4: Place the sponge matrix from Step 1 into the functionalized reagent that was shaken evenly in Step 2, and let it stand at 25°C for 5 minutes. During this process, use ultrasound and compression to remove air bubbles from the sponge matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, place the sponge matrix soaked in the functionalized reagent in an oven at 75°C to allow the ethanol solvent to evaporate. During the drying process, turn the sponge matrix over every 5 minutes. After 5 hours of thorough drying, a 5% concentration of ultrasensitive dual-response fluorescent imine material is obtained.

[0038] Application Example 4 An application of an ultrasensitive dual-response fluorescent imine material for the fluorescence detection of gaseous iodine includes: The ultrasensitive dual-response fluorescent imine material prepared in Example 3 was placed in a small beaker, which was then placed in a wide-mouth bottle and heated in an oven at 75°C. Samples were taken at different times for fluorescence detection. It was found that at an excitation wavelength of 280 nm, the material exhibited two fluorescence peaks in the absence of iodine absorption, at 378 nm and 640 nm. In an atmosphere with an iodine vapor concentration of approximately 551 μM, the fluorescence peak at 640 nm disappeared immediately after 1 second. The fluorescence intensity at 378 nm also decreased to some extent. This indicates that the ultrasensitive dual-response fluorescent imine material exhibits extremely sensitive dual-switch response to the fluorescence detection of gaseous iodine, enabling ultrafast early warning and quantitative detection of leaked gaseous iodine during nuclear energy utilization.

[0039] Comparative Example 1 This comparative example provides a method for preparing a fluorescent imine material, including the following steps: Step 1: Cut the original sponge into a cuboid with a length of 30mm and a width and thickness of 10mm to obtain an unmodified sponge matrix; immerse the sponge matrix in anhydrous ethanol, then place it in an ultrasonic oscillator and vibrate for 3 minutes. Repeat this process 3 times to wash away any impurities that may be present. Finally, dry it in an oven at a temperature of 75℃.

[0040] Step 3: Dissolve 1.5 mmol of terephthalaldehyde in 5 ml of ethanol solution, then add 0.75 mmol of lysine to the terephthalaldehyde ethanol solution. Sonicate the solution for 5 min to promote the dissolution of Congo red, obtaining a mixed ethanol solution A. Dissolve 0.5 mmol of tris(2-aminoethyl)amine in 5 ml of ethanol solution to obtain solution B. Mix solution A and solution B, sonicate for 5 min to allow solution A and solution B to react fully, then add ethanol solution to make up to 40 ml. Sonicate again for 3 min, then take 2 ml and add ethanol solution to make up to 20 ml. Shake well at 25°C and let stand for 15 min to obtain the functionalized reagent.

[0041] Step 4: Place the sponge matrix from Step 1 into the functionalized reagent that was shaken evenly in Step 2, and let it stand at 25°C for 5 minutes. During this process, use ultrasound and compression to remove air bubbles from the sponge matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, place the sponge matrix soaked in the functionalized reagent in an oven at 75°C to allow the ethanol solvent to evaporate. During the drying process, turn the sponge matrix over every 5 minutes. After 5 hours of thorough drying, a 10% fluorescent imine material is obtained.

[0042] Application Example 5 An application of a fluorescent imine material for the fluorescence detection of gaseous iodine includes: The ultrasensitive dual-response fluorescent imine material prepared in Comparative Example 1 was placed in a small beaker, which was then placed in a wide-mouth bottle and heated in an oven at 75°C. Samples were taken at different times for fluorescence detection. Using the fluorescence intensity of the ultrasensitive dual-response fluorescent imine material after adsorbing iodine vapor at 75°C for different times, a fluorescence peak at 526 nm was found. The fluorescence intensity at 526 nm decreased with increasing adsorbed iodine content. This indicates that, compared to the ultrasensitive dual-response fluorescent imine material prepared in Example 2, although the fluorescent imine material in Comparative Example 1 can quantitatively detect gaseous iodine, it lacks a second type of fluorescence peak and therefore cannot achieve ultrafast early warning of leaked gaseous iodine during nuclear energy utilization, thus failing to achieve the ultrasensitive dual-switch response effect similar to that of the ultrasensitive dual-response fluorescent imine material.

[0043] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0044] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A supersensitive dual-response fluorescent imine material, characterized in that, The structural formula of the ultrasensitive dual-response fluorescent imine material is: Wherein, TPA is terephthalaldehyde, TREN is tris(2-aminoethyl)amine, and n≥1.

2. A method for preparing the ultrasensitive dual-response fluorescent imine material as described in claim 1, characterized in that, Includes the following steps: S1. Cut the sponge matrix into cuboids with a length of 20-30 mm and a width and thickness of 5-15 mm to obtain an unmodified sponge matrix; soak the sponge matrix in anhydrous ethanol, vibrate it in an ultrasonic oscillator for 3-5 minutes, repeat 2-3 times, wash away impurities, and dry it for later use. S2. Add dialdehyde monomer and azo diamine monomer to an organic solvent, mix and then vibrate in an ultrasonic oscillator to mix them evenly to obtain a precursor solution; then add a crosslinking agent dissolved in an organic solvent to the precursor solution, so as to make up the volume by ultrasonication, and finally shake evenly and let stand to obtain a functionalized reagent. S3. Immerse the unmodified sponge matrix in a well-shaken functionalized reagent. Under conditions of 20~30℃, use ultrasound and compression to remove air bubbles from the sponge matrix, allowing the functionalized reagent to fully enter the cavity of the sponge matrix. Finally, dry the sponge matrix that has been immersed in the functionalized reagent at a certain temperature. During the drying process, turn the sponge matrix over every 3~10 minutes. After thorough drying, the ultrasensitive dual-response fluorescent imine material is obtained.

3. The preparation method of the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In S2, the crosslinking agent includes any one or a combination of two or more of spermidine, triethylenetetramine, diethylenetriamine, tri(2-aminoethyl)amine, and trimethylenetriamine.

4. The preparation method of the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In S2, the azo diamine monomer is Congo red.

5. The method for preparing the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In S2, the dialdehyde monomer includes any one or a combination of two or more of the following: pyromellitic methyl ether, terephthalic acid, hexamethylenedialdehyde, biphenyl dimethyl ether, and bipyridine dimethyl ether.

6. The method for preparing the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In S1 and S2, the organic solvent includes any one or a combination of two or more of dichloromethane, acetonitrile, ethanol, and ethyl acetate.

7. The method for preparing the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In S2, the volume of the organic solution is 5-10 mL; the ratio of dialdehyde monomer, azodiamine monomer, crosslinking agent, and organic solvent is 1-10 mmol: 1-5 mmol: 1-5 mmol: 20-40 mL; the reaction time after adding the crosslinking agent and ultrasonically adjusting the volume is 15-30 min; and the reaction temperature is 20-30 °C.

8. The method for preparing the ultrasensitive dual-response fluorescent imine material as described in claim 2, characterized in that, In step S3, the drying temperature is 70–80°C and the drying time is 2–5 hours.

9. An application of the ultrasensitive dual-response fluorescent imine material as described in claim 1, characterized in that, The aforementioned ultrasensitive dual-response fluorescent imine material is used for fluorescence detection of gaseous iodine. The specific method for fluorescence detection of gaseous iodine using the ultrasensitive dual-response fluorescent imine material includes: placing the ultrasensitive dual-response fluorescent imine material in a small beaker, then placing the small beaker in a wide-mouth bottle, heating it in an oven, taking samples at different times, and performing fluorescence detection. The fluorescence peak of the ultrasensitive dual-response fluorescent imine material after adsorption is compared with that before adsorption, thereby achieving ultrafast early warning and quantitative detection of gaseous iodine using the ultrasensitive dual-response fluorescent imine material.

10. The application of the ultrasensitive dual-response fluorescent imine material as described in claim 9, characterized in that, The oven heating temperature is 50~100℃, and the gaseous iodine concentration in the wide-mouth bottle ranges from 1~1000mg / L.

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