A fluorescent molecular probe with double-dynamic monitoring function and a preparation method and application thereof

Abstract

The present application relates to the technical field of organic small molecule material detection, in particular to a fluorescent molecular probe with double-dynamic monitoring function and a preparation method and application thereof. ‑ In DMF-water solution, the molecular probe presents a double-excitation-double-emission fluorescence with the increase of ClO ‑ concentration, and the fluorescence intensity presents a "on-off-on" double-transition dynamic detection response with the change of acid-base environment, which endows the molecular probe with double-dynamic monitoring function for ClO ‑ and the change of acid-base environment. ‑ The binary system has fluorescence emission "on-off" detection performance; and the detection is fast and sensitive. The molecular probe provided by the present application has the advantages of mild synthesis condition and simple preparation, which creates favorable conditions for its popularization and application.

Description

Technical Field

[0001] This invention relates to the field of organic small molecule material detection technology, specifically to a method for detecting ClO - Molecular probes and their applications exhibit dual-function dynamic monitoring characteristics, including dual excitation and dual emission of concentration changes with a "on-off-on-off" three-transformation fluorescence intensity and a "off-on-off" dual-transformation fluorescence intensity for changes in acid-base environment. Background Technology

[0002] Hypochlorous acid and sodium hypochlorite play an indispensable role in daily life and work due to their strong oxidizing properties and low cost. They are commonly used as bleaching agents, disinfectants, deodorizers, etc., and are widely applied in hygiene and disinfection in homes, hospitals, hotels, food processing plants, and other places, creating a healthy, safe, and convenient life for us. However, as highly effective chlorine-containing disinfectants, hypochlorous acid / sodium hypochlorite often produces chlorine gas, chlorates, and chlorites during the disinfection process. These chlorine-containing substances can pose potential hazards to the environment and human health. In biological systems, HClO / ClO... - As an important reactive oxygen species, HClO plays a vital role in physiological and biological processes, such as regulating cell life cycle, enhancing antigen immunity, and promoting wound repair and tissue regeneration. However, various studies have shown that the HClO / ClO ratio in vivo... - Abnormal concentrations of HClO / ClO can cause oxidative stress and tissue damage, leading to related diseases such as inflammation, neurodegeneration, cardiovascular disease, lung injury, rheumatoid arthritis, and even cancer. Therefore, whether in daily work and life or in physiological systems, the concentration of HClO / ClO is important. - Sensitive detection of concentration changes is essential.

[0003] Among various detection methods, fluorescent molecular detection, with its high sensitivity and low cost, is considered one of the ideal tools in environmental and biological research. Fluorescent molecular probes convert recognition at the molecular level into easily monitorable optical signals, offering advantages such as rapid detection, simple operation, high portability, and real-time detection capabilities. They have been widely applied in industrial and agricultural production, environmental engineering, medicine, and biological systems. Based on the different requirements of the analytes, numerous fluorescent molecular probes with diverse functions have been developed, including those with HClO / ClO... - Various fluorescent molecular probes for detecting performance have been reported. Due to HClO / ClO - HClO / ClO has strong oxidizing properties and a short lifespan. Currently, HClO / ClO is characterized by simple preparation, low cost, and sensitive on-site detection. - There are relatively few reports on fluorescent molecular probes, especially for ClO. - Fluorescent molecular probes with dynamic detection capabilities are even more unable to meet the growing market demand.

[0004] Furthermore, with rapid societal development, industrial and agricultural production processes that require specific acidic or alkaline environments to operate normally necessitate efficient pH detection technology to track processes, improve product quality, and enhance work efficiency. Simultaneously, the direct discharge of untreated waste alkalis and acids into the soil during production can cause changes in the surrounding environment's acidity and alkalinity, posing significant harm to human production and daily life. Therefore, sensitive analytical testing technologies are needed in industrial and agricultural production to constantly monitor the discharge of acidic and alkaline solutions that could pollute the water and soil resources upon which people depend for survival. Fluorescent molecular probes, due to their high sensitivity and ease of operation, have become a powerful tool for detecting pH changes in various fields. However, most reported pH molecular probe fluorescence signals increase / decrease with changes in acidity / alkalinity, exhibiting a single signal change. Meanwhile, the demand for sensitive detection of dynamic pH changes in people's work and daily lives is increasing. Therefore, to ensure the stability of acidic / alkaline working environments in specific processes, promote production, and improve efficiency, the development of easily prepared pH molecular probes capable of accurately monitoring acid-base environment transitions is an urgent need in various monitoring fields.

[0005] Schiff bases are a class of compounds containing imine functional groups. Their C=N double bond groups act as proton complexing sites and are sensitive to acidic environments. Furthermore, the C=N functional group is also the HClO / ClO group. - The specific recognition site, which is located in HClO / ClO - In its presence, it can be oxidized and broken down, leading to changes in intramolecular conjugation and inducing sensitive changes in optical signals. It is an ideal acid, HClO / ClO - One of the building blocks of molecular probes. During this period, the hydroxyl functional group, as a deprotonation site in an alkaline environment, has attracted much attention in the construction of pH-fluorescent molecular probes in alkaline environments. However, currently, there is a lack of readily available and simultaneously effective methods for constructing ClO₂-based probes. - Schiff base fluorescent molecular probes with dynamic detection capabilities for multiple "on-off" conversions of fluorescence signals in response to changes in acid-base environments have not yet been developed. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a dynamic detection method for ClO with dual-wavelength excitation, dual emission light conversion, and fluorescence intensity exhibiting a "on-off-on-off" three-conversion response. - A bifunctional molecular probe for dynamic detection of acid-base environment changes by red fluorescence "off-on-off" dual conversion, wherein the molecular probe is an asymmetric 4-hydroxy-m-phenylenedialdehyde-maleic anhydride dimer molecular probe.

[0007] This invention is achieved through the following technical solution: A fluorescent molecular probe with dual-dynamic monitoring function, wherein the probe is an asymmetric 4-hydroxy-m-phenylenedialdehyde-maleic anhydride dimer with the following structure: .

[0008] The molecular probe is easy to prepare and, based on the "on-off" multiple conversion of fluorescence emission signals, can achieve the detection of ClO₂. - It exhibits sensitive and rapid dynamic detection performance in response to changes in acidic and alkaline environments.

[0009] Another object of the present invention is to provide a method for preparing the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecule, comprising the following steps: 4-Hydroxy-m-phenylenedialdehyde was placed in a round-bottom flask containing a mixed solvent of N,N-dimethylformamide and anhydrous ethanol. Diaminomaleitrile and concentrated sulfuric acid were added sequentially, and the mixture was heated to reflux for 6-8 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to obtain an orange-yellow 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer.

[0010] Furthermore, in the above steps, the molar ratio of 4-hydroxy-m-phenylenedialdehyde and diaminomaleitrile is 1:2, the volume ratio of N,N-dimethylformamide and anhydrous ethanol in the mixed solvent is 1:4, the amount of mixed solvent added is limited to 15 mL of mixed solvent for every 1 mmol of 4-hydroxy-m-phenylenedialdehyde, and the amount of concentrated sulfuric acid added is 200 μL of concentrated sulfuric acid for every 1 mmol of 4-hydroxy-m-phenylenedialdehyde.

[0011] The reaction formula for preparing the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer is as follows: .

[0012] A third objective of this invention is to provide the asymmetric 4-hydroxy-m-phenylenealdehyde-maleitrile dimer in ClO - Applications of detection.

[0013] Specifically, the following is observed: In DMF- aqueous solution, as ClO... - With increasing concentration, under 520 nm excitation, the maximum fluorescence emission of the molecular probe near 612 nm gradually decreased until quenched; under 380 nm excitation, its maximum fluorescence emission at 612 nm gradually decreased, but the fluorescence emission at 468 nm initially increased significantly, and then decreased with the addition of ClO. - The concentration increases and then decreases, causing its fluorescence emission to exhibit a dynamic detection response with double excitation-double peak emission and intensity exhibiting a three-transition "on-off-on-off" pattern.

[0014] A fourth objective of this invention is to provide the application of the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer in the detection of acidic and alkaline environments.

[0015] Specifically, the molecular probe exhibits the following characteristics: In DMF-water solution, the molecular probe has a maximum fluorescence emission at 612 nm; as the NaOH concentration increases, its maximum fluorescence emission gradually decreases until quenching; as the HCl concentration increases, its fluorescence emission at 612 nm significantly decreases until quenching; the molecular fluorescence emission exhibits a "off-on-off" dual-conversion detection response with changes in acid-base environment.

[0016] A fifth object of the present invention is to provide the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecule in H2PO4. - Applications in detection.

[0017] Specifically, the molecular probe reacts with ClO in DMF-water solution. - The binary system exhibits maximum fluorescence emission near 612 nm after the addition of H2PO4. - Subsequently, the maximum fluorescence emission of the binary system decreases and eventually quenches, affecting H2PO4. - It has fluorescence emission "on-off" detection performance.

[0018] Compared with the prior art, the present invention has the following technical effects: In DMF-water solution, as ClO - With increasing concentration, the maximum fluorescence emission of the asymmetric 4-hydroxy-isophthalaldehyde-maleic nitrile dimer at 612 nm gradually decreases under 520 nm excitation. Under 380 nm excitation, its fluorescence emission decreases near 612 nm, while its fluorescence emission at 468 nm first significantly increases and then decreases. This effect is observed on ClO₂. - The molecule exhibits a dynamic detection response of dual excitation-dual emission fluorescence with a three-transition "on-off-on-off" pattern as concentration changes; with changes in acidity to alkalinity, the molecular probe shows a "off-on-off" dual-transition detection response at 612 nm fluorescence emission, which first increases and then decreases; the molecule is sensitive to ClO - The system achieves rapid, sensitive, real-time, and on-site dynamic detection of changes in acidic and alkaline environments, making it highly valuable for applications. Furthermore, the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecule -ClO... - Binary system for H2PO4 - It exhibits fluorescence emission "on-off" detection performance. The preparation process of the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecular probe provided by this invention has the advantages of low cost, high yield, and mild synthesis conditions, making it suitable for industrial implementation and creating favorable conditions for the widespread application of this asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecular probe. Attached Figure Description

[0019] Figure 1 The NMR spectrum is that of the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer.

[0020] Figure 2 Under 520 nm excitation, the asymmetric 4-hydroxy-isophthalaldehyde-maleic nitrile dimer molecules with different concentrations of ClO - Fluorescence detection response.

[0021] Figure 3 At 380 nm excitation, 0-100 equiv. ClO was added to the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecule. - Fluorescence detection response.

[0022] Figure 4 To induce an asymmetric 4-hydroxy-m-phenylene dialdehyde-maleic nitrile dimer at 380 nm excitation, 100-500 equiv. ClO - Fluorescence detection response.

[0023] Figure 5 Add 0-500 equiv. ClO to the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer. - Fluorescence intensity change trend graph.

[0024] Figure 6 The fluorescence response was detected by adding 0-2 equiv HCl to the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer.

[0025] Figure 7 The fluorescence detection response was obtained by adding 2-100 equiv HCl to the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer.

[0026] Figure 8 The fluorescence response was detected by adding 0-100 equiv. NaOH to the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer.

[0027] Figure 9 The fluorescence response was detected by adding 100-400 equiv. NaOH to the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer.

[0028] Figure 10 The graph shows the trend of fluorescence intensity changes after adding acid and base to the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer.

[0029] Figure 11 The selective fluorescence response is achieved by adding other anions to the asymmetric 4-hydroxy-isophthalaldehyde-maleic anion dimer.

[0030] Figure 12 ClO in the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer under 520 nm excitation - It competes with other anions for fluorescence detection response.

[0031] Figure 13 ClO in the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecule under 380 nm excitation - It competes with other anions for fluorescence detection response. Detailed Implementation

[0032] The present invention discloses a fluorescent molecular probe with dual-dynamic monitoring function, the molecular structure of which is as follows: .

[0033] It can be prepared by a one-step polymerization reaction using 4-hydroxy-m-phenylenedialdehyde and diaminomaleitrile as reactants. The synthesis reaction formula is as follows: .

[0034] Example 1 1 mmol of 4-hydroxy-m-phenylenedialdehyde was placed in a round-bottom flask containing 15 mL of N,N-dimethylformamide-anhydrous ethanol mixed solvent. 2 mmol of diaminomaleitrile and 200 μL of concentrated sulfuric acid were added sequentially, and the mixture was heated to reflux for 6 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to give 224.4 mg of orange-yellow compound A, with a yield of 68%.

[0035] Example 2 1 mmol of 4-hydroxy-m-phenylenedialdehyde was placed in a round-bottom flask containing 15 mL of N,N-dimethylformamide-anhydrous ethanol mixed solvent. 2 mmol of diaminomaleitrile and 200 μL of concentrated sulfuric acid were added sequentially, and the mixture was heated to reflux for 8 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to give 234.4 mg of orange-yellow compound B, with a yield of 71%.

[0036] Compounds A and B obtained in Examples 1 and 2, respectively, were analyzed and determined. Their NMR spectra were... Figure 1 To, see Figure 1 The NMR data are as follows: 1 ¹H NMR (DMSO-d₆, 400 MHz): 11.14 (s, 1H), 8.61 (d, 2H), 8.21 (s, 1H), 8.11 (m, 1H), 7.98 (s, 2H), 7.80 (s, 2H), 7.04 (d, 1H); indicating that compounds A / B are basically consistent with the theoretical values ​​of 4-hydroxy-m-phenylenedialdehyde-maleic anhydride dimers. Therefore, the molecular structures of compounds A and B can be confirmed as follows: That is, the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleic nitrile dimer.

[0037] Example 3 Asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer pair ClO - Detection performance: In 90% DMF-water solution, at a concentration of 2×10 -5 Different concentrations of ClO were added to the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecule at mol / L. - Fluorescence emission tests revealed that, at an excitation wavelength of 520 nm, the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleic anhydride dimer exhibited maximum fluorescence emission near 612 nm; with the addition of ClO... - As the concentration gradually increases, ClO - After increasing the concentration of ClO2 by 50 times, the fluorescence emission of this molecule at 612 nm decreased significantly. Further increases in ClO2... - When the concentration reaches 100 times, its fluorescence spectrum remains essentially unchanged; see details below. Figure 2 Under the above conditions, at an excitation wavelength of 360 nm, ClO - When the concentration was increased 100-fold from 0, the weak fluorescence emission of the molecular probe at 612 nm was quenched, while its fluorescence emission at around 468 nm was significantly enhanced. (See details...) Figure 3 However, continuing to increase ClO - When the concentration is increased 500 times, its fluorescence emission at around 468 nm decreases significantly, as detailed in [reference needed]. Figure 4 These results indicate that the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer is associated with ClO - The concentration change exhibits a dynamic detection response with dual excitation and biphasic emission, and the fluorescence intensity displays a three-transition "on-off-on-off" pattern. See details... Figure 5 .

[0038] Example 4 Fluorescence detection performance of asymmetric 4-hydroxy-isophthalaldehyde-maleitrile dimer under acid-base changes: In 90% DMF aqueous solution, at a concentration of 2×10⁻⁶... -5 The fluorescence emission spectra of the asymmetric 4-hydroxy-isophthalaldehyde-maleitrile dimer molecule at mol / L under different acid and alkaline conditions are as follows: With increasing HCl concentration from 0 to 2 molar equivalents, the maximum fluorescence emission intensity near 612 nm of this molecule significantly decreases. See the detailed results below. Figure 6 When the HCl concentration was further increased to 100 molar equivalents, its fluorescence emission remained essentially unchanged; see the results below. Figure 7 During this period, as the concentration of NaOH increased from 0 to 50 molar equivalents, the maximum fluorescence emission intensity of the molecule near 612 nm decreased significantly; when the NaOH concentration increased from 50 to 100 molar equivalents, the decrease in fluorescence emission intensity was slower. Specific results can be found in [the table below]. Figure 8When the NaOH concentration was further increased to 400 molar equivalents, the fluorescence emission intensity remained essentially unchanged. See the results below. Figure 9 These results indicate that the fluorescence emission intensity of the asymmetric 4-hydroxy-isophthalaldehyde-maleic anhydride dimer exhibits a dynamic "off-on-off" detection response as the environmental conditions change from acidic to alkaline. See the detailed results below. Figure 10 .

[0039] Example 5 The selectivity of asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer for anionic fluorescence detection: In 90% DMF-water solution, at a concentration of 2×10⁻⁶ -5 Adding 20 times the amount of Cl to the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecule at a concentration of mol / L - ,Br - I - C2O4 2- CO3 2- HCO3 - H2PO4 - SO4 2- NO2 - NO3 - SCN - SiO3 2- Fluorescence emission tests revealed that under 520 nm excitation, the molecule exhibits a maximum fluorescence emission peak around 612 nm; Cl - ,Br - I - C2O4 2- CO3 2- HCO3 - H2PO4 - SO4 2- NO2 - NO3 - SCN - SiO3 2- After the addition of anions, its fluorescence emission spectrum showed almost no significant change; see the detailed results below. Figure 11 The fluorescence emission was significantly reduced when 20 times the concentration of NaClO was added, a stark contrast to the reduction observed with this addition. These results indicate that, among the anions tested above, the asymmetric 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer molecular probe is effective against ClO₂. - It exhibits good fluorescence selective response.

[0040] Example 6 ClO in the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecular probe - Optical competitiveness with other anions: In a 90% DMF- aqueous solution, at a concentration of 2 × 10⁻⁶ -5ClO was simultaneously added to the asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecular probe at a concentration of mol / L. - Fluorescence emission spectroscopy studies of mixed systems with different anions showed that at an excitation wavelength of 520 nm, the molecular probe containing 30 times the amount of ClO₂... - Subsequently, its binary system exhibits a maximum fluorescence emission near 612 nm; H2PO4 - After adding the above binary system, its fluorescence emission near 612 nm is significantly reduced; Cl - ,Br - I - C2O4 2- CO3 2- HCO3 - SCN - SO4 2- NO2 - NO3 - After the anion is added to the binary system, the ternary mixture reacts with the molecular probe-ClO - The fluorescence emission spectra of the binary system are similar; see [link to results] for details. Figure 12 Similarly, the above solution, under an excitation wavelength of 380 nm, produces H2PO4. - Adding asymmetric 4-hydroxy-m-phenylene dialdehyde-maleitrile dimer molecule-ClO - After the binary system, its fluorescence emission decreases and eventually quenches near the 612 nm position; other anions such as Cl - ,Br - I - C2O4 2- CO3 2- HCO3 - SCN - SO4 2- NO2 - NO3 - After adding the above binary system, its fluorescence emission spectrum remains essentially unchanged; see the attached table for details. Figure 13 These indicate that the asymmetric 4-hydroxy-isophthalaldehyde-maleic nitrile dimer not only affects ClO - It exhibits good selective detection performance, and it is similar to ClO - The resulting binary system is related to H2PO4 - It has fluorescence emission "on-off" detection performance.

Claims

1. A fluorescent molecular probe with dual-dynamic monitoring function, wherein the molecular probe is an asymmetric 4-hydroxy-m-phenylenedialdehyde-maleic anhydride dimer with the following structure: .

2. A method for preparing a fluorescent molecular probe with dual-dynamic monitoring function as described in claim 1, characterized in that: Includes the following steps: 4-Hydroxy-m-phenylenedialdehyde was placed in a round-bottom flask containing a mixed solvent of N,N-dimethylformamide and anhydrous ethanol. Diaminomaleitrile and concentrated sulfuric acid were added sequentially, and the mixture was heated to reflux for 6-8 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to obtain an orange-yellow 4-hydroxy-m-phenylenedialdehyde-maleitrile dimer.

3. The method for preparing the fluorescent molecular probe with dual-dynamic monitoring function according to claim 2, characterized in that: In the above steps, the molar ratio of 4-hydroxy-m-phenylenedialdehyde and diaminomaleitrile is 1:2, the volume ratio of N,N-dimethylformamide and anhydrous ethanol in the mixed solvent is 1:4, the amount of mixed solvent added is limited to 15 mL of mixed solvent for every 1 mmol of 4-hydroxy-m-phenylenedialdehyde, and the amount of concentrated sulfuric acid added is 200 μL of concentrated sulfuric acid for every 1 mmol of 4-hydroxy-m-phenylenedialdehyde.

4. A fluorescent molecular probe with dual-dynamic monitoring function as described in claim 1 in ClO - Applications in detection, wherein the applications do not involve the diagnosis and treatment of diseases, are characterized by: In DMF-aqueous solution, with ClO - As the concentration gradually increases, the fluorescence emission of the molecular probe gradually decreases around 612 nm under excitation at 520 nm; under excitation at 380 nm, with the increase of ClO... - As the concentration gradually increases, the maximum fluorescence emission at 612 nm gradually decreases, while the fluorescence emission at 468 nm first increases significantly and then decreases significantly, resulting in a dynamic detection response with double excitation-double peak emission and intensity exhibiting a "on-off-on-off" three-transition pattern.

5. The application of a fluorescent molecular probe with dual-dynamic monitoring function as described in claim 1 in the detection of acid-base environments, wherein the application does not involve the diagnosis and treatment of diseases, characterized in that: In DMF-water solution, the maximum fluorescence emission intensity of the molecular probe at 612 nm decreased significantly with increasing NaOH concentration; with the addition of HCl concentration, its fluorescence emission at 612 nm also decreased significantly; the fluorescence intensity of the molecule exhibited a "off-on-off" dual-conversion detection response with changes in acid-base environment.

6. A fluorescent molecular probe with dual-dynamic monitoring function as described in claim 1 in H2PO4 - Applications in detection, wherein the applications do not involve the diagnosis and treatment of diseases, are characterized by: Add H2PO4 to DMF-water solution - Then, the molecular probe reacted with ClO - The binary system exhibits a maximum fluorescence emission decreases and eventually quenches around 612 nm, with its fluorescence emission displaying an "on-off" detection response.

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