A molecular sensor with dual-mode pentad anion detection function and a preparation method and application thereof

Abstract

This invention relates to the field of organic small molecule material detection technology, specifically to a molecular sensor with dual-mode-pentaplex anion detection function, its preparation method, and its application. The multi-site complexation properties of the molecular sensor enable it to interact with HSO4. ‑ CrO4 2+ CO3 2+ SiO3 2‑ and OH ‑ After interaction, it exhibits a dual-mode signal detection response with varying fluorescence emission "on-off" and ultraviolet absorption changes; and this molecule -HSO4 ‑ / CrO4 2‑ The binary system reacts to CO3. 2‑ / SiO3 2‑ / CrO4 2‑ CO3 2‑ / SiO3 2‑ It features dual-signal detection capabilities of fluorescence emission and ultraviolet absorption, enabling not only precise and rapid detection of five molecules with a single-molecule sensor, but also achieving the detection of CO3. 2‑ SiO3 2‑ CrO4 2‑ The three / three / two multiple detection functions of ions, with accurate, fast and sensitive detection, have created favorable conditions for its widespread application.

Description

Technical Field

[0001] This invention relates to the field of organic small molecule material detection technology, specifically to a method for detecting HSO4⁻ and CrO4. 2+ CO3 2+ SiO3 2- and OH - The o-vanillin-thiadiazole molecular sensor and its application. Background Technology

[0002] Anions are negatively charged ions that are ubiquitous in nature and organisms, playing a vital role in biomedicine, chemical industry, agricultural production, and pollution control. Anions are prevalent in biological systems; amino acids and polypeptides are representative organic anionic compounds, while many inorganic anions such as nitrate, carbonate, and thiosulfate are also abundant and play important roles. However, excessive anions can cause significant harm to the ecological environment and human health. For example, carbonate readily hydrolyzes in water, making it more alkaline and helping to maintain the stability of the internal environment and the relative pH of the stomach. However, excessive intake usually causes alkalosis, leading to symptoms such as shallow and rapid breathing, rapid heart rate, and altered consciousness; in severe cases, it can cause coma and even death. CrO4²⁻ is highly water-soluble and mobile, entering the human body through the digestive tract, respiratory tract, and skin contact, causing dermatitis, ulcers, nasal septum perforation, and other lesions. Long-term exposure increases the risk of lung cancer. Chromium accumulation in the environment leads to soil degradation and aquatic ecological imbalance, amplifying its harmful effects through bioaccumulation in the food chain. Excessive intake of silicate ions can damage lung tissue, stimulate the proliferation of pulmonary fibroblasts, leading to pulmonary fibrosis, loss of elasticity, and ventilation disorders; in severe cases, it can even cause cancer. Silicate ions are also highly toxic to aquatic organisms. They combine with aluminum and iron ions in water to form colloids, affecting the respiration and photosynthesis of aquatic organisms, and in severe cases, causing death and disrupting the balance of the aquatic ecosystem. Therefore, developing sensitive and convenient methods for detecting anions is crucial.

[0003] Currently, anion analysis and detection mainly include ion chromatography, electrochemical analysis, and fluorescence analysis. Ion chromatography is primarily used for the sensitive detection of hydrophilic anions, but its widespread practical application is limited by the high cost of instruments, complex operation, and high detection costs. Electrochemical sensing mainly uses cyclic voltammetry to determine anions, utilizing changes in peak potential or peak current intensity before and after electrode binding with an anion to achieve anion identification and detection. While this method is convenient, fast, and has a low detection limit, it requires a large number of samples and suffers from poor selectivity. In contrast, fluorescent molecular sensors convert the detection at the molecular level into easily monitorable optical signals such as ultraviolet and fluorescence, achieving in-situ, real-time, rapid, and sensitive detection, and have been widely used in industrial and agricultural production, environmental monitoring, and other fields. Unlike the numerous and diverse cation molecular sensors, research on anion molecular sensors has only recently gained attention. This is mainly due to the structural characteristics of anions themselves: First, anions have a larger radius and relatively lower electron cloud density than isoelectronic cations, resulting in weaker complexation performance with molecular sensors; second, anions possess specific geometric configurations, such as spherical, linear, planar triangular, tetrahedral, and octahedral shapes, requiring molecular sensors to have matching spatial configurations; furthermore, anions exhibit a strong solvation tendency and are sensitive to the acidity or alkalinity of solutions, existing only within a narrow pH range. Therefore, research on molecular sensors for sensitive detection of anions is currently limited, especially on molecular sensors with multiple recognition capabilities. Multifunctional fluorescent molecular sensors not only avoid the preparation process of multiple single-molecule sensors but also save time and money compared to the individual detection of single-function molecular sensors. Therefore, developing easy-to-prepare, sensitive, rapid, and widely applicable multifunctional anion molecular sensors is an urgent need in various monitoring fields.

[0004] Furthermore, with rapid social development, various waste alkalis and acids generated during industrial and agricultural production processes, which require specific acidic or alkaline environments to function normally, are directly discharged into the soil without treatment. This can cause changes in the acidity and alkalinity of the surrounding environment, posing a significant threat to human production and life. Therefore, the industrial and agricultural production sectors require sensitive analytical testing technologies 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 sensors, due to their high sensitivity, in-situ real-time operation, and ease of use, have become a powerful tool for detecting pH changes in various fields. Therefore, developing easy-to-prepare, sensitive, and rapid pH molecular sensors is essential. Thiadiazole is a five-membered heterocyclic conjugated structure containing S and N atoms. In the construction of fluorescent molecular sensors, it can serve as a multi-anion recognition site, making it a fluorescent linker group with great application value. However, currently, the construction of sensors with thiadiazole as the core bridging group, containing hydroxyl and imine functional groups, and targeting HSO4⁻ and CrO4⁻, is still in its early stages. 2+CO3 2+ SiO3 2- OH - Molecular sensors with different signal detection capabilities, such as ions, have not yet been developed. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method that is easy to prepare and simultaneously treats HSO4⁻ and CrO4⁻. 2+ CO3 2+ SiO3 2- and OH - A molecular sensor with dual-mode signals of different ultraviolet absorption and fluorescence emission and five detection functions is provided. The molecular sensor is a symmetrical o-vanillin-thiadiazole molecular sensor.

[0006] This invention is achieved through the following technical solution: A molecular sensor with dual-mode-pentaplex anion detection capability, wherein the sensor is a symmetrical o-vanillin-thiadiazole molecule with the following structure: .

[0007] The molecular sensor is easy to fabricate and, based on different optical signal responses, can detect HSO4⁻ and CrO4⁻. 2+ CO3 2+ SiO3 2- OH - Ions and other rapid, accurate, and on-site detection.

[0008] Another object of the present invention is to provide a method for preparing the symmetrical o-vanillin-thiadiazole molecule, comprising the following steps: 2,5-Diamino-1,3,4-thiadiazole was placed in a round-bottom flask containing a mixed solvent of N,N-dimethylformamide and anhydrous ethanol. 2-hydroxy-3-methoxybenzaldehyde and glacial acetic acid were added sequentially, and the mixture was heated to reflux for 8-10 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to obtain an orange-yellow o-vanillin-thiadiazole molecular compound.

[0009] Furthermore, the molar ratio of 2,5-diamino-1,3,4-thiadiazole to 2-hydroxy-3-methoxybenzaldehyde is 1:2, the volume ratio of N,N-dimethylformamide to anhydrous ethanol in the mixed solvent is 1:10, the amount of the mixed solvent added is limited to 11 mL of mixed solvent for every 1 mmol of 2,5-diamino-1,3,4-thiadiazole, and the amount of glacial acetic acid added is 100 μL of glacial acetic acid for every 1 mmol of 2,5-diamino-1,3,4-thiadiazole.

[0010] The preparation reaction formula for the symmetrical o-vanillin-thiadiazole molecule is as follows: .

[0011] A third objective of this invention is to provide the symmetrical o-vanillin-thiadiazole molecule in HSO4 - CrO4 2+ CO3 2+ and SiO3 2- Applications of detection.

[0012] Specifically, the molecular sensor exhibits the following characteristics in DMF-water solution: a maximum characteristic absorption peak near 360 nm; with the addition of HSO4... - Subsequently, its maximum absorption near 360 nm blue-shifted to 346 nm, accompanied by a significant decrease in absorbance, while a new maximum absorption peak appeared at 265 nm, resulting in a precise bimodal signal. A 265 / A 360 Changes; CrO4 2- After addition, its absorption near 360 nm was significantly enhanced, and a strong absorption appeared at 265 nm; the addition of CO3... 2-- Subsequently, its maximum absorption near 360 nm blue-shifted to 352 nm, accompanied by a decrease in absorbance, while a new maximum absorption peak appeared at 455 nm, making... A 455 / A 360 Increase from 0.07 to 1.09; add SiO3 2- Subsequently, its maximum absorption near 360 nm blue-shifted to 352 nm, accompanied by a decrease in absorbance, while a broad absorption peak appeared in the 400-500 nm range. Fluorescence emission studies showed that the molecular sensor exhibited weak maximum fluorescence emission near 427 nm; the addition of HSO4... - At that time, its maximum fluorescence emission redshifted to 486 nm, accompanied by an approximately 6.7-fold increase in fluorescence emission; with the addition of SiO3 2- With CO3 2- At that time, the maximum fluorescence emission of this molecule redshifted to 585 nm and 593 nm, and the fluorescence emission was enhanced by 5.5 and 5.8 times, respectively; with the addition of CrO4 2- Subsequently, its maximum fluorescence emission redshifted to 590 nm, an increase of 1.3 times, indicating that the molecular sensor effectively detected HSO4. - SiO3 2- CO3 2- and CrO4 2- It has dual-mode fluorescence enhancement and ultraviolet absorption, and four-mode detection performance.

[0013] A fourth objective of this invention is to provide the application of the symmetrical o-vanillin-thiadiazole molecule in the detection of alkaline environments.

[0014] Specifically, the molecular sensor exhibits the following characteristics: In a 50% DMF aqueous solution, it displays weak fluorescence emission near 427 nm; with increasing NaOH concentration, the fluorescence emission at 427 nm shows minimal change, while it significantly enhances near 590 nm. During this period, the maximum absorption near 360 nm gradually decreases, while a new characteristic absorption peak appears near 446 nm. A 446 / A 360 The ratio increased from 0.02 to 1.6, indicating that the o-vanillin-thiadiazole molecule has a significant dual-mode detection response to changes in alkaline environment, with fluorescence emission "on-off" and precise UV absorption bi-peak ratio.

[0015] The fifth object of the present invention is to provide the symmetrical o-vanillin-thiadiazole molecule with HSO4. - The resulting binary system in SiO3 2- CO3 2- and CrO4 2- Applications of detection.

[0016] Specifically, the molecular sensor was prepared by adding 10 times the amount of HSO4 to a DMF-aqueous solution. - Subsequently, the binary system exhibits strong fluorescence emission near 486 nm; CO3 2- After the addition of the above binary system, its fluorescence emission at 486 nm decreases, while a strong fluorescence emission appears at 593 nm; SiO3 2- After the addition of the above binary system, its fluorescence emission at 486 nm decreased, while a new strong fluorescence emission appeared at 585 nm; CrO4 2- After incorporating the aforementioned binary system, its fluorescence emission at 486 nm decreased, while a new fluorescence emission appeared at 590 nm. UV absorption studies indicate that this molecular sensor is compatible with HSO4. - The binary system exhibits a maximum absorption peak around 265 nm and a weak absorption around 346 nm; CO3 2- After being added to the aforementioned binary system, its absorption near 352 nm is enhanced, and a new absorption peak appears at 455 nm, exhibiting a unique dual absorption peak characteristic; SiO3 2- After being added to this binary system, its absorption near 352 nm is enhanced, and it exhibits a broad, structure-free absorption in the 400-500 nm range; CrO4 2-Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system was established, its absorption at 346 nm showed a slight red shift, accompanied by a significant increase in absorbance, while its absorbance at 265 nm also increased; indicating that the o-vanillin-thiadiazole molecule-HSO4 - Binary system for SiO3 2- CO3 2- and CrO4 2- It has dual signal detection capabilities, including enhanced fluorescence emission and ultraviolet absorption.

[0017] The sixth object of the present invention is to provide the symmetrical o-vanillin-thiadiazole molecule with CrO4 2+ The resulting binary system in SiO3 2- and CO3 2- Applications of detection.

[0018] Specifically, the following occurs: 10 times the amount of CrO4 is added to the o-vanillin-thiadiazole molecule in DMF-aqueous solution. 2+ Subsequently, the binary system exhibits a relatively weak maximum fluorescence emission near 590 nm; CO3 2- After the addition of the above binary system, its fluorescence emission at 593 nm is significantly enhanced; SiO3 2- After being added to the above binary system, its fluorescence emission at 590 nm was significantly enhanced, indicating that the o-vanillin-thiadiazole molecule reacts with CrO4. 2+ The resulting binary system affects CO3 2- SiO3 2- It has sensitive fluorescence emission "off-on" detection performance.

[0019] Compared with the prior art, the present invention has the following technical effects: the o-vanillin-thiadiazole molecule contains multiple complexing sites such as N / S atoms, imine, and hydroxyl groups, giving it a strong ion complexing ability, which is particularly effective with HSO4. - CO3 2+ CrO4 2+ SiO3 2- and OH - After complexation, they exhibit distinct fluorescence emission "on-off" states and dual-signal detection responses based on changes in ultraviolet absorption; o-vanillin-thiadiazole molecules -HSO4 are detected through mechanisms such as ion exchange reactions. - / CrO4 2- The binary system reacts to CO3. 2- / SiO3 2- / CrO4 2- CO3 2- / SiO3 2-It features dual-signal detection capabilities of fluorescence emission and ultraviolet absorption, enabling not only precise and rapid detection of five molecules with a single-molecule sensor, but also achieving the detection of CO3. 2- SiO3 2- CrO4 2- The sensor offers triple / triple / diple detection capabilities for ions, with rapid, sensitive, and intuitive signals, making it highly valuable for applications. The o-vanillin-thiadiazole molecular sensor preparation process provided by this invention boasts advantages such as high yield, mild synthesis conditions, and simple preparation technology, making it suitable for industrial implementation and creating favorable conditions for the widespread application of this o-vanillin-thiadiazole molecular sensor. Attached Figure Description

[0020] Figure 1 The NMR spectrum of a symmetrical o-vanillin-thiadiazole molecule is shown.

[0021] Figure 2 The UV absorption detection response of the o-vanillin-thiadiazole molecule to different anions.

[0022] Figure 3 The fluorescence emission response of the o-vanillin-thiadiazole molecule to different anions was detected.

[0023] Figure 4 The response of o-vanillin-thiadiazole molecules to ultraviolet absorption of different concentrations of NaOH is shown.

[0024] Figure 5 The fluorescence emission response of the o-vanillin-thiadiazole molecule to different concentrations of NaOH is shown.

[0025] Figure 6 The fluorescence emission response of the o-vanillin-thiadiazole molecule to different concentrations of HCl.

[0026] Figure 7 The effect of o-vanillin-thiadiazole molecules on different concentrations of HSO4 - Ultraviolet absorption response.

[0027] Figure 8 The o-vanillin-thiadiazole molecule pairs with different concentrations of HSO4 - Fluorescence emission response.

[0028] Figure 9 For o-vanillin-thiadiazole molecules to pair with different concentrations of SiO3 2- Ultraviolet absorption response.

[0029] Figure 10 For o-vanillin-thiadiazole molecules to pair with different concentrations of SiO3 2- Fluorescence emission response.

[0030] Figure 11 For o-vanillin-thiadiazole molecules to different concentrations of CrO42- Ultraviolet absorption response.

[0031] Figure 12 For o-vanillin-thiadiazole molecules to different concentrations of CrO4 2- Fluorescence emission response.

[0032] Figure 13 The o-vanillin-thiadiazole molecule for different concentrations of CO3 2- Ultraviolet absorption response.

[0033] Figure 14 The o-vanillin-thiadiazole molecule for different concentrations of CO3 2- Fluorescence emission response.

[0034] Figure 15 HSO4 in o-vanillin-thiadiazole molecule - It competes with other anions for UV absorption response.

[0035] Figure 16 HSO4 in o-vanillin-thiadiazole molecule - It competes with other anion fluorescence emission responses.

[0036] Figure 17 CrO4 in o-vanillin-thiadiazole molecule 2- With CO3 2- / SiO3 2- Fluorescence emission competition response. Detailed Implementation

[0037] The molecular sensor disclosed in this invention, which has a dual-mode-pentaplex anion detection function, has the following molecular structure: .

[0038] It can be prepared by a one-step polymerization reaction using 2,5-diamino-1,3,4-thiadiazole and 2-hydroxy-3-methoxybenzaldehyde as reactants. The synthesis reaction formula is as follows: .

[0039] Example 1 1 mmol of 2,5-diamino-1,3,4-thiadiazole was placed in a round-bottom flask containing 11 mL of N,N-dimethylformamide-ethanol (1:10) mixed solvent. 2 mmol of 2-hydroxy-3-methoxybenzaldehyde and 100 μL of glacial acetic 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 290.3 mg of orange-yellow compound A, with a yield of 76%.

[0040] Example 2 1 mmol of 2,5-diamino-1,3,4-thiadiazole was placed in a round-bottom flask containing 10 mL of N,N-dimethylformamide-ethanol (1:19) mixed solvent. 2 mmol of 2-hydroxy-3-methoxybenzaldehyde and 100 μL of glacial acetic acid were added sequentially, and the mixture was heated to reflux for 10 hours. The resulting mixture was filtered, washed with anhydrous ethanol, and dried to give 301.8 mg of orange-yellow compound B, with a yield of 79%.

[0041] 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 spectroscopy data are as follows: 1 ¹H NMR (DMSO-d6, 400 MHz): 11.28 (s, 1H), 10.94 (s, 1H), 9.24 (s, 1H), 8.84 (s, 1H), 7.50 (d, 1H), 7.38 (d, 1H), 7.26 (d, 1H), 7.18 (d, 1H), 6.99 (m, 2H), 3.87 (d, 6H); indicating that compounds A / B are basically consistent with the theoretical values ​​of o-vanillin-thiadiazole. Therefore, the molecular structures of compounds A and B can be confirmed as follows: That is, a symmetrical o-vanillin-thiadiazole molecule.

[0042] Example 3 UV absorption optical detection performance of o-vanillin-thiadiazole molecule for different anions: In a 50% water content DMF-water solution, at a concentration of 1×10⁻⁶... -5 UV absorption assays of o-vanillin-thiadiazole molecules with 10 molar equivalents of different anions showed that the o-vanillin-thiadiazole molecule exhibits a maximum characteristic absorption peak around 360 nm; the addition of HSO4... - Subsequently, its maximum absorption near 360 nm blue-shifted to 346 nm, accompanied by a significant decrease in absorbance, while a new maximum absorption peak appeared at 265 nm, resulting in a precise bimodal signal. A 265 / A 360 Increased from 0.27 to 3.14; CrO4 2- After addition, CrO4 2- After addition, its absorption near 360 nm was significantly enhanced, and a strong absorption appeared at 265 nm; the addition of CO3... 2--Subsequently, its maximum absorption near 360 nm blue-shifted to 352 nm, accompanied by a decrease in absorbance, while a new maximum absorption peak appeared at 455 nm, making... A 455 / A 360 Increase from 0.07 to 1.09; add SiO3 2- Subsequently, its maximum absorption near 360 nm blue-shifts to 352 nm, accompanied by a decrease in absorbance, while a broad absorption peak appears in the 400-500 nm range; other anions, such as F... - Cl - ,Br - I - SCN - HCO3 - SO4 - NO3 - AcO - C2O4 - H2PO4 - After its addition, the UV absorption spectrum of the o-vanillin-thiadiazole molecule remained essentially unchanged. Figure 2 The above results indicate that the o-vanillin-thiadiazole molecule has a positive effect on HSO4. - CrO4 2+ CO3 2+ and SiO3 2- It has different ultraviolet absorption signal detection performance.

[0043] Example 4 Fluorescence detection performance of o-vanillin-thiadiazole molecule for different anions: In a 50% aqueous solution of DMF, at a concentration of 1×10⁻⁶... -5 Fluorescence emission optical detection experiments with different anions added to mol / L o-vanillin-thiadiazole molecules at 10 molar equivalents showed that the molecular sensor exhibited a weak maximum fluorescence emission near 427 nm; the addition of HSO4... - At that time, its maximum fluorescence emission redshifted to 486 nm, accompanied by an approximately 6.7-fold increase in fluorescence emission; with the addition of SiO3 2- With CO3 2- At that time, the maximum fluorescence emission of this molecule redshifted to 585 nm and 593 nm, and the fluorescence emission was enhanced by 5.5 and 5.8 times, respectively; with the addition of CrO4 2- Subsequently, its maximum fluorescence emission redshifted to 590 nm, increasing by 1.3 times. Other anions, such as F... - Cl - ,Br - I - SCN - HCO3- SO4 - NO3 - AcO - C2O4 - H2PO4 - After its addition, the fluorescence emission spectrum of the o-vanillin-thiadiazole molecule remained essentially unchanged. Figure 3 The above results indicate that the molecular sensor is effective against HSO4. - SiO3 2- CO3 2- and CrO4 2- It has dual-signal and quadruple-detection performance with different fluorescence enhancement and ultraviolet absorption.

[0044] Example 5 The o-vanillin-thiadiazole molecular sensor's optical detection function in different alkaline environments: in a 50% water-content DMF-water solution, at a concentration of 1×10⁻⁶... -5 The fluorescence emission spectra of o-vanillin-thiadiazole molecules in the presence of different concentrations of NaOH are as follows: The molecular sensor exhibits weak fluorescence emission near 427 nm, while almost no fluorescence emission occurs in the 520-640 nm range; as the NaOH concentration increases, the fluorescence emission at 427 nm gradually blue-shifts to 414 nm, and the fluorescence emission near 590 nm gradually increases, becoming 5.4 times stronger. Figure 4 During this period, as the NaOH concentration increased, the maximum absorption of this molecule near 360 nm gradually decreased, while its absorption shifted to 353 nm, and a new characteristic absorption peak appeared near 446 nm, causing... A 446 / A 360 Increased from 0.02 to 1.6, Figure 5 These findings indicate that the o-vanillin-thiadiazole molecule exhibits a significant "on-off" fluorescence emission response and a precise dual-mode detection response with a bimodal ratio of UV absorption peaks in response to changes in alkaline environments.

[0045] Example 6 The o-vanillin-thiadiazole molecular sensor's optical detection function in different acidic environments: in a 50% DMF-water solution with a concentration of 1×10⁻⁶. -5 The fluorescence emission spectra of the o-vanillin-thiadiazole molecular sensor at mol / L in the presence of different concentrations of HCl are as follows: As the concentration of added HCl increases from 0 to 100 molar equivalents, the maximum fluorescence emission of the molecular sensor near 427 nm remains essentially unchanged. See [link to specific results] for details. Figure 6 These results indicate that the o-vanillin-thiadiazole molecular sensor exhibits a certain degree of stability in acidic environments.

[0046] Example 7 o-vanillin-thiadiazole molecular sensor for different concentrations of HSO4 - Optical detection function of ions: In a DMF- aqueous solution with a water content of 50%, the concentration is 1×10⁻⁶. -5 Different concentrations of HSO4 were added to the o-vanillin-thiadiazole molecular sensor at mol / L. - The fluorescence emission spectrum at time is as follows: In the free state, the o-vanillin-thiadiazole molecule has a weak maximum fluorescence emission near 427 nm; with HSO4 - As the concentration increased from 0 to 10 molar amounts, the fluorescence emission near 427 nm gradually red-shifted to 486 nm, accompanied by a significant increase in fluorescence emission intensity; subsequently, further increases in HSO4... - With increasing HSO4 concentration, its fluorescence emission spectrum remains essentially unchanged (Figure 7). Ultraviolet absorption spectroscopy studies show that... - As the concentration increased from 0 to 10 molar equivalents, the maximum absorption of the o-vanillin-thiadiazole molecule near 360 nm blue-shifted to 346 nm, accompanied by a significant decrease in absorbance, while a new maximum absorption peak appeared at 265 nm. Further increases in HSO4... - Even at concentrations reaching 20 molar equivalents, its ultraviolet absorption spectrum remains unchanged. Figure 8 These indicate that the o-vanillin-thiadiazole molecule has an effect on HSO4. - The ions exhibit sensitive fluorescence "on-off" and ultraviolet absorption dual-signal detection performance.

[0047] Example 8 o-vanillin-thiadiazole molecular sensor for different concentrations of SiO3 2- Optical detection function of ions: In a DMF- aqueous solution with a water content of 50%, the concentration is 1×10⁻⁶. -5 Different concentrations of SiO3 were added to the o-vanillin-thiadiazole molecular sensor at mol / L. 2- The fluorescence emission spectrum at that time is as follows: In the free state, the o-vanillin-thiadiazole molecule has a weak maximum fluorescence emission near 427 nm; with SiO3 2- As the concentration increased from 0 to 10 molar amounts, the fluorescence emission near 427 nm gradually red-shifted to 585 nm, accompanied by a significant increase in fluorescence emission intensity; subsequently, further increases in SiO3... 2- With increasing SiO3 concentration, its fluorescence emission spectrum remains essentially unchanged (Figure 9). Ultraviolet absorption spectroscopy studies indicate that... 2- As the concentration increased from 0 to 5 molar equivalents, the maximum absorption of the o-vanillin-thiadiazole molecule near 360 nm blue-shifted to 352 nm, accompanied by a decrease in absorbance, while the absorption at 458 nm slightly increased; further increasing the SiO3 concentration...2- When the concentration ranges from 5 to 10 molar equivalents, its absorption at 352 nm shows little change, but a broad absorption without structural features appears in the 400-500 nm range. Figure 10 This indicates that the o-vanillin-thiadiazole molecule affects SiO3 2- The ions exhibit sensitive fluorescence "on-off" and ultraviolet absorption dual-signal detection performance.

[0048] Example 9 o-vanillin-thiadiazole molecular sensor for different concentrations of CrO4 2- Optical detection function of ions: In a DMF- aqueous solution with a water content of 50%, the concentration is 1×10⁻⁶. -5 Different concentrations of HSO4 were added to the o-vanillin-thiadiazole molecular sensor at mol / L. - The fluorescence emission spectrum at time is as follows: In the free state, the o-vanillin-thiadiazole molecule has a weak maximum fluorescence emission near 427 nm; with HSO4 - As the concentration increased from 0 to 10 molar amounts, the fluorescence emission near 427 nm gradually red-shifted to 486 nm, accompanied by a significant increase in fluorescence emission intensity; subsequently, further increases in HSO4... - With increasing concentration, its fluorescence emission spectrum remains essentially unchanged. Figure 11 Ultraviolet absorption spectroscopy studies show that with the increase of HSO4... - As the concentration increased from 0 to 10 molar equivalents, the maximum absorption of the o-vanillin-thiadiazole molecule shifted from around 360 nm to 346 nm, accompanied by a significant decrease in absorbance, while a new maximum absorption peak appeared at 265 nm. Further increases in HSO4... - Even at concentrations reaching 20 molar equivalents, its ultraviolet absorption spectrum remains unchanged. Figure 12 These indicate that the o-vanillin-thiadiazole molecule has an effect on HSO4. - The ions exhibit sensitive fluorescence "on-off" and ultraviolet absorption dual-signal detection performance.

[0049] Example 10 o-vanillin-thiadiazole molecular sensor for different concentrations of CO3 2- Optical detection function of ions: In a DMF- aqueous solution with a water content of 50%, the concentration is 1×10⁻⁶. -5 Different concentrations of SiO3 were added to the o-vanillin-thiadiazole molecular sensor at mol / L. 2- The fluorescence emission spectrum at that time is as follows: In the free state, the o-vanillin-thiadiazole molecule has a weak maximum fluorescence emission near 427 nm; with SiO3 2-As the concentration increased from 0 to 10 molar amounts, the fluorescence emission near 427 nm gradually red-shifted to 585 nm, accompanied by a significant increase in fluorescence emission intensity; subsequently, further increases in SiO3... 2- With increasing concentration, its fluorescence emission spectrum remains essentially unchanged. Figure 13 Ultraviolet absorption spectroscopy studies show that with the increase of SiO3... 2- As the concentration increased from 0 to 5 molar equivalents, the maximum absorption of the o-vanillin-thiadiazole molecule near 360 nm blue-shifted to 352 nm, accompanied by a decrease in absorbance, while the absorption at 458 nm slightly increased; further increasing the SiO3 concentration... 2- When the concentration ranges from 5 to 10 molar equivalents, its absorption at 352 nm shows little change, but a broad absorption without structural features appears in the 400-500 nm range. Figure 14 This indicates that the o-vanillin-thiadiazole molecule affects SiO3 2- The ions exhibit sensitive fluorescence "on-off" and ultraviolet absorption dual-signal detection performance.

[0050] Example 11 HSO4 in o-vanillin-thiadiazole molecular sensor - Fluorescence performance competing with other anions: In a 50% aqueous solution of DMF-, at a concentration of 1×10⁻⁶... -5 HSO4 was added simultaneously to o-vanillin-thiadiazole molecules at a concentration of mol / L. - Fluorescence emission spectroscopy studies of mixed systems with different anions showed that the addition of 10 times HSO4 to this molecular sensor... - Subsequently, its binary system exhibits strong fluorescence emission near 486 nm; CO3 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system was established, its fluorescence emission at 486 nm decreased, while a strong fluorescence emission appeared at 593 nm, similar to the addition of o-vanillin-thiadiazole molecule-CO3. 2- Fluorescence emission spectrum of binary system; SiO3 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system is established, its fluorescence emission at 486 nm decreases, while a new fluorescence emission appears at 585 nm. CrO4 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system was established, its fluorescence emission at 486 nm decreased, while a new fluorescence emission appeared at 590 nm; F - Cl - ,Br - I - SCN- HCO3 - SO4 - NO3 - AcO - C2O4 - H2PO4 - The addition of anionic o-vanillin-thiadiazole molecules to HSO4 - After the binary system was established, its fluorescence emission spectrum remained essentially unchanged, as shown in the figure. Figure 15 These findings indicate that the o-vanillin-thiadiazole molecule is not only effective against HSO4 - It exhibits good selective detection performance, compared with HSO4 - The resulting binary system affects CO3 2- SiO3 2- CrO4 2 It has different fluorescence emission biphasic ratio detection performance.

[0051] Example 12 HSO4 in o-vanillin-thiadiazole molecular sensor - Study on UV absorption performance competing with other anions: In a 50% water-content DMF- aqueous solution, at a concentration of 1×10⁻⁶... -5 HSO4 was added simultaneously to o-vanillin-thiadiazole molecules at a concentration of mol / L. - UV absorption spectroscopy studies of mixed systems with different anions show that the addition of 10 times the amount of HSO4 to this molecular sensor... - Subsequently, its binary system exhibits a maximum absorption peak near 265 nm and a weak absorption near 346 nm; CO3 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system is formed, its absorbance decreases at 265 nm, its absorption increases near 346 nm, and a new absorption peak appears at 455 nm, exhibiting a unique dual absorption peak characteristic; SiO3 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system is formed, its absorbance decreases at 265 nm, its absorption increases near 346 nm, and it exhibits a broad absorption without structural characteristics in the 400-500 nm range; CrO4 2- Add o-vanillin-thiadiazole molecule-HSO4 - After the binary system was established, its absorption at 346 nm showed a slight red shift, accompanied by a significant increase in absorbance, while its absorbance at 265 nm also increased; F - Cl - ,Br - I - SCN -HCO3 - SO4 - NO3 - AcO - C2O4 - H2PO4 - The addition of anionic o-vanillin-thiadiazole molecules to HSO4 - Following the binary system, the ternary hybrid system and the molecular sensor with HSO4 - The fluorescence emission spectra of the binary system are similar; see [link to results] for details. Figure 16 These findings indicate that the o-vanillin-thiadiazole molecule is not only effective against HSO4 - It exhibits good selective detection performance, compared with HSO4 - The resulting binary system affects CO3 2- SiO3 2- CrO4 2 It has different dual-signal detection performance of fluorescence emission enhancement and ultraviolet absorption.

[0052] Example 13 CrO4 in o-vanillin-thiadiazole molecular sensor 2 With SiO3 2- and CO3 2- Optical Competitive Performance Study: In a DMF-water solution with a water content of 50% and a concentration of 1×10⁻⁶... -5 Adding 10 times the amount of CrO4 to o-vanillin-thiadiazole molecules at a concentration of mol / L 2- Subsequently, the binary system exhibits a relatively weak maximum fluorescence emission near 590 nm; CO3 2- After the addition of the above binary system, its fluorescence emission at 593 nm is significantly enhanced; SiO3 2- After being added to the aforementioned binary system, its fluorescence emission at the 590 nm position was significantly enhanced. This indicates that the o-vanillin-thiadiazole molecule reacts with CrO4... 2+ The resulting binary system affects CO3 2- SiO3 2- It exhibits sensitive fluorescence emission "off-on" and ultraviolet absorption dual-signal detection performance. See details for further information. Figure 17 .

Claims

1. A molecular sensor with dual-mode-pentaplex anion detection function in HSO4 - CrO4 2- CO3 2- and SiO3 2- The application of the detection, wherein the application does not involve the diagnosis and treatment of diseases, is characterized in that... The molecular sensor is a symmetrical o-vanillin-thiadiazole molecule, with the following structure: ； In DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function exhibits weak maximum fluorescence emission near 427 nm; when HSO4 is added... - CrO4 2- CO3 2- and SiO3 2- Subsequently, its maximum fluorescence emission exhibits varying degrees of redshift and "on-off" detection response, accompanied by dual-signal detection responses with different ultraviolet absorption changes.

2. The molecular sensor with dual-mode-pentaplex anion detection function according to claim 1 in CO3 2- Its application in detection is characterized by: In DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function reacts with HSO4. - The constructed binary system was used for dual-mode detection and identification of CO3 based on the fluorescence bimodal ratio signal and ultraviolet absorption changes. 2- ; Alternatively, in DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function is combined with CrO4. 2- The constructed binary system is used for fluorescence "on-off" detection and identification of CO3. 2- .

3. The molecular sensor with dual-mode-pentaplex anion detection function according to claim 1 in SiO3 2- Its application in detection is characterized by: In DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function reacts with HSO4. - The constructed binary system was used for dual-mode detection and identification of SiO3 based on the fluorescence bimodal ratio signal and ultraviolet absorption changes. 2- ; Alternatively, in DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function is combined with CrO4. 2- The constructed binary system is used for fluorescence "on-off" detection and identification of SiO3. 2- .

4. The molecular sensor with dual-mode-pentaplex anion detection function according to claim 1 in CrO4 2- Its application in detection is characterized by: In DMF-aqueous solution, the molecular sensor with dual-mode-pentaplex anion detection function reacts with HSO4. - The constructed binary system is used for dual-mode detection and identification of CrO4 based on fluorescence emission and ultraviolet absorption changes. 2- .

5. An application of a molecular sensor with dual-mode-pentaplex anion detection function in alkaline environment detection, wherein the application does not involve the diagnosis and treatment of diseases, characterized in that... The molecular sensor is a symmetrical o-vanillin-thiadiazole molecule, with the following structure: ； In DMF-aqueous solution, the molecular sensor with dual-mode pentagonal anion detection function exhibits weak fluorescence emission near 427 nm. As the NaOH concentration increases, the fluorescence emission at 427 nm changes little, while the fluorescence emission near 590 nm increases significantly. At the same time, the maximum absorption of the molecule near 360 nm gradually decreases, while a new characteristic absorption peak appears near 446 nm. It has a dual-mode detection response with a significant fluorescence emission "on-off" switch and a precise ratio of ultraviolet absorption double peaks in response to changes in alkaline environment.

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