A bis-ester-substituted-2-mercaptoimidazophenazine fluorescent sensor, its synthesis and application in the detection of ethylenediamine

Abstract

A novel fluorescent sensor PAM based on bis(ester)-substituted-2-mercaptoimidazo[1,2-a]phenazine was designed and synthesized in this invention. This sensor can selectively detect the volatile organic pollutant ethylenediamine (EDA) through fluorescence and visible light. Meanwhile, PAM can also be used as a solid-state fluorescent sensor, which can not only achieve the naked-eye detection of EDA vapor, but also has good stability. Research shows that the bis(ester) groups on the PAM structure undergo "nucleophilic substitution" with EDA to form a product with different fluorescence emissions, which leads to obvious fluorescence changes after the interaction between PAM and EDA. Therefore, this reactive detection method can distinguish EDA from other aliphatic amines and provide a simple and stable platform for its detection. In addition, a portable paper test kit was prepared, which can conveniently and rapidly realize the multi-phase sensing and qualitative analysis of EDA.

Description

Technical Field

[0001] The present invention relates to a fluorescence sensor capable of selectively detecting ethylenediamine (EDA) in liquid and gas phases and a synthesis method thereof; the present invention also relates to the use of the fluorescence sensor for naked-eye recognition and fluorescence detection of ethylenediamine, belonging to the fields of chemical synthesis and detection of organic volatile pollutants. Background Art

[0002] Ethylenediamine (EDA) is a widely used chemical industrial raw material and intermediate. It has strong reducibility and alkalinity and has important applications in the fields of medicine, agriculture, dyes, and antioxidants. However, ethylenediamine is highly toxic and potentially carcinogenic. It has currently been identified as a diagnostic disease marker for respiratory infections. Its vapor is highly irritating and corrosive to the skin and eyes, and even the liquid can cause burns to the human body. Long-term exposure or inhalation of ethylenediamine can cause various serious diseases, such as pneumonia, pulmonary edema, asthma, and even serious damage to the liver and kidneys. Moreover, ethylenediamine vapor also has a certain degree of environmental pollution, and its leakage poses a threat to the environment and ecology, such as water pollution and soil corrosion. Therefore, real-time detection and separation of ethylenediamine in solutions and air are crucial for human health and environmental protection. Among the currently reported ethylenediamine detection methods, the instrumental detection method is limited due to the need to use expensive instruments. In addition, the sensing methods of most reported chemical sensors are too single, with poor stability and lack of convenience in actual operation. Therefore, the development of an easily synthesized, low-cost, highly stable, and convenient-to-use fluorescence sensor that can simultaneously achieve high selectivity and high sensitivity detection of ethylenediamine solutions and their vapors has important requirements and application prospects in the field of environmental science. In the present invention, we designed and synthesized a fluorescence sensor (PAM) based on imidazophenazine derivatives. This sensor can detect ethylenediamine (EDA) through multiple channels and has specific selectivity and high sensitivity. The sensor molecule has the advantages of being easily synthesized and convenient to apply. Summary of the Invention

[0003] The object of the present invention is to provide a fluorescence sensor capable of efficiently detecting ethylenediamine (EDA) in both solution and gas phases and a synthesis method thereof;

[0004] Another object of the present invention is to provide the application of the above fluorescence sensor in the detection of ethylenediamine.

[0005] I. Fluorescence Sensor Molecule and Its Synthesis

[0006] The main molecular formula of the sensor molecule of the present invention is: C 19 H 16 N4O4S, labeled as: PAM, and the structural formula is:

[0007] .

[0008] Synthesis: Using acetone as the solvent, first add methyl chloroacetate, potassium iodide, and potassium carbonate to the above reaction solvent in sequence, and stir at 25 - 28 °C for 1 - 2 hours. Then add 2-mercaptoimidazo[1,2-a]phenazine P1 to the reaction solution, reflux and stir at 64 - 67 °C for 10 - 15 h. After the reaction is completed, filter while it is hot and collect the filtrate. After the filtrate is cooled to room temperature, a precipitate is formed, which is washed with absolute ethanol and acetone, and then recrystallized with DMF / H2O to obtain a yellow product, which is the fluorescent sensor host molecule PAM. Among them, the molar ratio of 2-mercaptoimidazo[1,2-a]phenazine to methyl chloroacetate is 1:2 - 1:3; the molar ratio of methyl chloroacetate to potassium iodide is 1:2; the molar ratio of methyl chloroacetate to potassium carbonate is 1:2.

[0009] Synthesis route:

[0010]

[0011] The mass spectrum and hydrogen spectrum of the sensor host molecule PAM are shown in Figure 1 、 Figure 2 。

[0012] I. Stability performance of the fluorescent sensor

[0013] Figure 3 This is the change in fluorescence intensity of the EtOH solution of the fluorescent sensor PAM of the present invention at different pH values (λ ex = 360 nm), and the pH value ranges from 1 to 13. As can be seen from Figure 3 , within the pH value range of 1 - 13, the fluorescence intensity of the sensor PAM remains basically stable, indicating that PAM can be well applied to various environmental conditions such as acidic, neutral, and alkaline.

[0014] Figure 4 This is the change in fluorescence intensity of the EtOH solution of the fluorescent sensor PAM of the present invention at different times. As can be seen from Figure 3 , as time increases (0 - 120 h), the fluorescence intensity of the sensor PAM changes relatively little within 120 hours and remains basically stable. [[ID=3,4]]

[0015] Therefore, the fluorescent sensor PAM has a flexible pH range and relatively ideal optical stability.

[0016] II. Detection performance of the fluorescent sensor for ethylenediamine (EDA)

[0017] Figure 5 This is the fluorescence spectrum (λ ex = 360 nm) after adding EDA to the EtOH solution of the fluorescent sensor PAM of the present invention. As can be seen from Figure 5The results show that the addition of EDA can cause the emission peak of the sensor PAM solution to redshift, and its fluorescence intensity decreases significantly. At the same time, under the irradiation of a 365 nm ultraviolet lamp, the fluorescence color of the PAM solution changes from the original light green to bright yellow.

[0018] Figure 6 This is the ultraviolet spectrum (λ ex = 360 nm) after adding EDA to the EtOH solution of the fluorescence sensor PAM of the present invention. From Figure 6 The results show that the addition of EDA can broaden and significantly reduce the absorption peak of the sensor PAM solution at 390 nm. At the same time, the solution color shows an obvious visual change effect from yellow to orange.

[0019] Figure 7 This is the fluorescence spectrum after adding ethylenediamine, acetone, methanol, acetonitrile, formaldehyde, ammonia water, dichloromethane, ethyl acetate, chloroform, tetrahydrofuran, pyridine, 2-n-butylamine, and ethanolamine to the EtOH solution of the fluorescence sensor PAM of the present invention. Figure 7 It shows that compared with EDA, there is no such obvious change in the peak shift and the decrease in fluorescence intensity of the sensor PAM solution, which fully demonstrates that PAM can selectively detect ethylenediamine in the solution phase by fluorescence in the EtOH solution.

[0020] Figure 8 This is the fluorescence change when the solid powder of the fluorescence sensor PAM of the present invention is exposed to the vapors of 2-n-butylamine, ethanolamine, ethylenediamine, hydrazine hydrate, acetone, ammonia water, methanol, acetonitrile, dichloromethane, formaldehyde, chloroform, tetrahydrofuran, pyridine, and ethyl acetate. From Figure 8 The results show that only the vapor of ethylenediamine can quench the yellow fluorescence of the PAM solid powder, which fully demonstrates that PAM can selectively detect ethylenediamine vapor by fluorescence.

[0021] Figure 9 、 10 These are the fluorescence titration and the lowest detection limit after adding EDA to the EtOH solution of the fluorescence sensor PAM of the present invention. From Figure 9 It shows that the lowest fluorescence detection limit of the sensor PAM for EDA is 6.98 × 10 -7 M, which indicates that this fluorescence sensor (PAM) can highly sensitively detect ethylenediamine (EDA).

[0022] III. Detection mechanism analysis

[0023] Figure 11 This is the infrared spectrum diagram of the sensor molecule PAM of the present invention after reacting with ethylenediamine (EDA). From Figure 11 It can be seen that at 1741 cm -1There are obvious characteristic peaks here, which are the stretching vibration absorption peaks of the ester carbonyl group. After reacting with EDA, between 3200 cm -1 ~3400 cm -1 two stretching vibration absorption peaks of -NH at 3259 cm -1 and 3373 cm -1 appear. At the same time, the wavenumber of the absorption peak at the carbonyl group shifts from 1741 cm -1 to 1731 cm -1 . This result is attributed to the shift of the absorption peak to lower wavenumbers caused by the change of the ester group to an amide bond.

[0024] Figure 12 This is the mass spectrum of the sensor molecule PAM of the present invention after reacting with ethylenediamine (EDA). The product PAM-EDA formed when PAM binds to EDA was found on the mass spectrum, and the m / z value of its [M+H] + is 452.17462.

[0025] Figure 13 This is the NMR titration diagram of the sensor molecule PAM of the present invention with different equivalents of ethylenediamine (EDA). Among them, a, b, and c correspond to the changes in the hydrogen proton signal peaks after adding 0, 2, and 4 equivalents of EDA, respectively. It can be seen from Figure 13 that when EDA is added to the host PAM, new hydrogen proton signal peaks H1, H2, and H3 appear, which are attributed to the proton signal peaks on -NH, -CH2, and -NH2, respectively. It shows that when PAM reacts with EDA, the ester group and the amine undergo "nucleophilic substitution" to form a product PAM-EDA with different fluorescence emissions, thereby realizing the reactive detection of ethylenediamine (EDA).

[0026] Figure 14 This is the theoretical calculation of the sensor molecule PAM of the present invention using Gaussian 09 after adding ethylenediamine (EDA). Using density functional theory (DFT), optimization was carried out at the WB3LYP / 6-311G **(d, p) level to obtain the structural views of PAM and PAM + ethylenediamine. Analysis shows that after the sensor molecule PAM binds to EDA, charge migration occurs, causing a significant change in fluorescence.

[0027] IV. Practical Application of the Fluorescent Sensor for the Detection of Ethylenediamine (EDA)

[0028] Figure 15 is the prepared paper test kit for the detection of ethylenediamine. It can be seen from Figure 15 that this paper test kit can conveniently and quickly detect EDA in both liquid and gaseous states. Therefore, this PAM can realize the multiphase sensing of EDA and has good application prospects.

[0029] In summary, a novel fluorescent sensor PAM based on bis(ester)-substituted-2-mercaptoimidazophenazine was designed and synthesized in this invention, which can selectively detect the volatile organic pollutant ethylenediamine (EDA). When EDA is added, an obvious visual change in the solution color from yellow to orange can be observed. Meanwhile, under the irradiation of a 365 nm ultraviolet lamp, the fluorescence color of the PAM solution changes from light green to bright yellow. In addition, PAM can also be used as a solid-state fluorescent sensor, which can not only achieve the naked-eye detection of EDA vapor, but also has good stability. Most importantly, the lowest detection limit of PAM for EDA is 6.98 × 10 -7 M, which is very low and reaches the level of highly sensitive detection. This detection process is caused by the "nucleophilic substitution" of the bis(ester) group on the PAM structure with EDA to form a product with different fluorescence emissions. Therefore, this reactive detection method can distinguish EDA from other aliphatic amines and provides a simple and stable platform for its detection. In addition, a portable paper test kit was also prepared, which can conveniently and quickly achieve the multi-phase sensing and qualitative analysis of EDA. Brief Description of the Drawings

[0030] Figure 1 It is the mass spectrum of the sensor molecule PAM of this invention;

[0031] Figure 2 It is the hydrogen spectrum of the sensor molecule PAM of this invention;

[0032] Figure 3 It is the fluorescence intensity change spectrum of the EtOH solution of the fluorescent sensor PAM of this invention at different pH values (λ ex =360 nm);

[0033] Figure 4 It is the fluorescence intensity change spectrum of the EtOH solution of the fluorescent sensor PAM of this invention at different times;

[0034] Figure 5 It is the fluorescence spectrum of the EtOH solution of the fluorescent sensor PAM of this invention after adding ethylenediamine (EDA);

[0035] Figure 6 It is the ultraviolet spectrum of the EtOH solution of the fluorescent sensor PAM of this invention after adding ethylenediamine (EDA);

[0036] Figure 7 It is the fluorescence spectrum of the EtOH solution of the fluorescent sensor PAM of this invention after adding different volatile organic compounds respectively;

[0037] Figure 8Fluorescence color change diagram of the fluorescent sensor PAM solid powder of the present invention before and after being exposed to different volatile organic compounds;

[0038] Figure 9 Fluorescence titration diagram of adding ethylenediamine (EDA) to the EtOH solution of the fluorescent sensor PAM of the present invention;

[0039] Figure 10 Lowest fluorescence detection limit of adding ethylenediamine (EDA) to the EtOH solution of the fluorescent sensor PAM of the present invention;

[0040] Figure 11 Infrared spectrum diagram of the fluorescent sensor molecule PAM of the present invention and after reacting with ethylenediamine (EDA);

[0041] Figure 12 Mass spectrum diagram of the fluorescent sensor molecule PAM of the present invention and after reacting with ethylenediamine (EDA);

[0042] Figure 13 Nuclear magnetic titration diagram of adding ethylenediamine (EDA) to the sensor molecule PAM of the present invention;

[0043] Figure 14 Gaussian theoretical calculation diagram of the sensor molecule PAM of the present invention and ethylenediamine (EDA);

[0044] Figure 15 Paper test kit for the sensor molecule PAM of the present invention to respond to ethylenediamine (EDA). Detailed implementation manners

[0045] The following further illustrates the synthesis of the sensor molecule PAM of the present invention and the application of fluorescence detection of ethylenediamine (EDA) through specific examples.

[0046] Example 1 Synthesis of the fluorescent sensor PAM

[0047] Synthesis of the fluorescent sensor PAM: Using acetone (30 mL) as the reaction solvent, weigh methyl chloroacetate (0.54 g, 5 mmol) and potassium iodide (1.66 g, 10 mmol) and add them to the above solvent. After stirring at room temperature for 1 hour, add potassium carbonate (1.38 g, 10 mmol) to the above mixed solution and continuously stir for 30 minutes to obtain a white slurry. Then, add 2-mercaptoimidazo[1,2-a]phenazine P1 (0.504 g, 2 mmol) to the above reaction solution, heat to 65 °C and stir under reflux for 12 hours. After the reaction is completed, filter while it is hot to remove inorganic salts to obtain a filtrate. After the filtrate is cooled to room temperature, a yellow precipitate precipitates out. Then filter under reduced pressure, and recrystallize through DMF / H2O to obtain a yellow product PAM, yield: 31.50%. The mass spectrum and hydrogen spectrum diagrams of the sensor molecule PAM are shown inFigure 1 and Figure 2 。

[0048] Example 2: Detection of Ethylenediamine in Liquid Phase by PAM

[0049] Pipette 0.5 mL of the EtOH solution of the fluorescent sensor molecule PAM (C PNM = 2×10 -4 M) into a series of colorimetric tubes, and respectively add ethylenediamine, acetone, methanol, acetonitrile, formaldehyde, ammonia water, dichloromethane, ethyl acetate, chloroform, tetrahydrofuran, pyridine, 2-n-butylamine, and ethanolamine (C = 0.1 M). If the fluorescence color of the sensor molecule solution changes from light green to bright yellow, it indicates that ethylenediamine is added; if the fluorescence of the sensor molecule does not change, it indicates that ethylenediamine is not added. If the solution color of the sensor molecule changes from yellow to orange, it indicates that ethylenediamine is added; if the solution color of the sensor molecule does not change, it indicates that ethylenediamine is not added.

[0050] Example 3: Detection of Ethylenediamine (EDA) Vapor by PAM

[0051] When the PAM solid powder is respectively exposed to the vapors of 2-n-butylamine, ethanolamine, ethylenediamine, hydrazine hydrate, acetone, ammonia water, methanol, acetonitrile, dichloromethane, formaldehyde, chloroform, tetrahydrofuran, pyridine, and ethyl acetate, if the yellow fluorescence of the PAM solid powder is quenched, it indicates that it is ethylenediamine vapor; if the yellow fluorescence of the PAM solid powder cannot be quenched, it is other vapors.

Claims

1. A double ester substituted 2-mercaptoimidazophenazine fluorescent sensor molecule, the structural formula of which is: 。 2. The synthesis method of the bis-ester group substituted-2-mercaptoimidazophenazine fluorescent sensor molecule as claimed in claim 1, characterized in that: Using acetone as the solvent, methyl chloroacetate, potassium iodide, and potassium carbonate are first added sequentially to the above reaction solvent and stirred at 25-28°C for 1-2 hours. 2-Mercaptoimidazole-phenazine is then added to the reaction solution and refluxed and stirred at 64-67°C for 10-15 hours. After the reaction is completed, the filtrate is filtered while hot and collected. After the filtrate is cooled to room temperature, a precipitate is precipitated, washed with anhydrous ethanol and acetone, and then recrystallized to obtain a yellow product.

3. The synthesis method of the double ester group-substituted-2-mercaptoimidazophenazine fluorescent sensor molecule according to claim 2, characterized in that: The molar ratio of 2-mercaptoimidazophenazine to methyl chloroacetate is 1:2-1:

3.

4. Use of the diester-substituted-2-mercaptoimidazophenazine fluorescent sensor molecule according to claim 1 in the detection of ethylenediamine for non-diagnostic and therapeutic purposes.

5. The application according to claim 4, characterized in that: The fluorescent sensor molecule was used for the selective detection of ethylenediamine in the liquid phase. Ethylenediamine, acetone, methanol, acetonitrile, formaldehyde, ammonia, dichloromethane, ethyl acetate, chloroform, tetrahydrofuran, pyridine, 2-n-butylamine, and ethanolamine were added to the EtOH solution of the diester-substituted-2-mercaptoimidazophenazine fluorescent sensor molecule, respectively. Only the addition of ethylenediamine caused the color of the EtOH solution of the fluorescent sensor molecule to show a significant visual change from yellow to orange. At the same time, under 365 nm ultraviolet light, the fluorescence color of the EtOH solution of the fluorescent sensor molecule was observed to change from the original light green to bright yellow. However, the EtOH solution of the fluorescent sensor molecule did not change significantly after the addition of other substances.

6. The application according to claim 4, characterized in that: The fluorescent sensor molecule selectively detects ethylenediamine vapor. The solid powder of the diester-substituted-2-mercaptoimidazophenazine fluorescent sensor molecule is exposed to the vapors of 2-n-butylamine, ethanolamine, ethylenediamine, hydrazine hydrate, acetone, ammonia, methanol, acetonitrile, dichloromethane, formaldehyde, chloroform, tetrahydrofuran, pyridine, and ethyl acetate, respectively. Only ethylenediamine vapor can quench the yellow fluorescence of the fluorescent sensor molecule solid powder.

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