Application and method of a fluorescent ionic liquid in the detection of nitrophenol isomers
By preparing the fluorescent ionic liquid (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate, its high fluorescence and stability were utilized to solve the problem of identifying p-nitrophenol and o-nitrophenol in water, thus realizing a rapid and low-cost detection method.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU UNIV OF SCI & TECH
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies are insufficient to effectively distinguish between p-nitrophenol and o-nitrophenol, two nitrophenol isomers with similar physical properties, in water bodies. Furthermore, traditional methods are costly and complex to operate.
A fluorescent ionic liquid (poly)1,3-di(N-methylimidazolyl)propane-1,4-naphthalenedicarboxylate was prepared to identify nitrophenol isomers in water using fluorescence spectroscopy. The method employed was simple and utilized to enhance its high fluorescence and stability.
This method enables rapid identification of nitrophenol isomers, is simple to operate, low in cost, and exhibits strong fluorescence, making it suitable for environmental detection.
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Figure CN119775209B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a fluorescent ionic liquid, the compound of which can be used as a fluorescent probe to identify nitrophenol isomers in the living environment, such as the atmosphere, water, and soil. Background Technology
[0002] Nitrophenols, as important organic chemical raw materials and intermediates, have wide applications in pesticides, dyes, pharmaceuticals, and explosives. However, these compounds are often toxic, posing a potential threat to the environment and human health. The United Nations Environment Programme has listed them as a "priority pollutant." p-Nitrophenol and o-nitrophenol, as two major isomers of nitrophenols, have similar physical and chemical properties, making direct chemical identification difficult. Existing technologies disclose methods for preparing fluorescent ionic liquids containing a bisnaphthalene ring structure, which yield fluorescent ionic liquids with advantages such as good stability, high fluorescence intensity, and high sensitivity. Existing technologies also provide a method for identifying the isomers of p-nitrophenol and o-nitrophenol in water. Compared with reported techniques such as high-performance liquid chromatography and electrochemical methods, this method has advantages such as low detection cost, simple operation, short response time, and high stability. Summary of the Invention
[0003] One objective of this invention is to propose a fluorescent ionic liquid that is a high-molecular-weight polymer whose anionic structure contains a naphthalene ring structure, exhibiting relatively stable structure. This invention is suitable for analyzing and identifying the isomers of p-nitrophenol and o-nitrophenol in water, and features short response time and simple operation.
[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0005] Step 1: Add 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid to a single-necked flask in sequence. Reflux the mixture at 30 °C for 24 h to obtain a clear brown solution, which is sodium 1,4-naphthalenedicarboxylic acid solution.
[0006] Step 2: Add 1,3-dibromopropane (8 mL), N-methylimidazole (12 mL), and acetone (50 mL) sequentially to the three-necked flask. Stir and reflux at 45°C for 20 h, wash three times with 50 mL of acetone each time, and filter to obtain a white solid powder.
[0007] Step 3: Add the prepared sodium 1,4-naphthalenedicarboxylate solution and 8.3 g of the white solid product obtained in Step 2 to a single-necked flask, and stir the reaction at 50 °C for 24 h. The prepared solution is then rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate, with a yield of 97.4%.
[0008] The ionic liquid (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate compound of this invention is a brownish-red viscous liquid. It provides a new approach for the detection and identification of p-nitrophenol and o-nitrophenol isomers in water pollutants using fluorescence spectroscopy. The preparation principle of the fluorescent ionic liquid (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate compound is as follows:
[0009] Step 1: Synthesis principle of 1,4-naphthalenedicarboxylate solution:
[0010]
[0011] Step Two: The Synthetic Principle of 1,3-Di(N-methylimidazolyl)propane:
[0012]
[0013] Step 3: Principle of final product synthesis
[0014]
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0016] ① This invention discloses a fluorescent ionic liquid, named (poly)1,3-di(N-methylimidazolyl)propane-1,4-naphthalenedicarboxylate, which has a simple synthesis method. Furthermore, compared with commonly used ionic liquids such as haloimidazolium, imidazolium hexafluorophosphate, and imidazolium tetrafluoroborate, this invention exhibits higher fluorescence properties.
[0017] ② This invention exhibits strong fluorescence properties. The aqueous solution (4 mmol / L) of the fluorescent ionic liquid of this invention, with an excitation wavelength of 330 nm, has a maximum fluorescence intensity of approximately 3.5 × 10⁻⁶. 4 au, with an emission wavelength of 370nm.
[0018] ③This invention is a novel fluorescent ionic liquid. Its preparation method is simple to operate, requires little equipment investment, and is easy to scale up and produce.
[0019] ④ The fluorescent ionic liquid of this invention has excellent environmental performance, with "zero" volatilization, no odor, and recyclability.
[0020] The present invention provides a novel approach for the preparation of fluorescent ionic liquid (poly) 1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate compounds, which allows for the differentiation of p-nitrophenol and o-nitrophenol based on the degree of quenching. This approach offers a new method for detecting pollutants in water using fluorescence spectroscopy. Attached Figure Description
[0021] The following diagram is provided to further illustrate the structure and performance of the product.
[0022] Figure 1 This is the 1H NMR spectrum of (poly)1,3-di(N-methylimidazolyl)propane-1,4-naphthalenedicarboxylate:
[0023] 1 H NMR (400MHz, DMSO) δ = 2.56-2.61 (2H), δ = 3.85 (6H), δ = 4.23-4.26 (4H), δ = 7.37-7 .40(1H), δ=7.67(1H), δ=7.74(2H), δ=7.85(2H), δ=8.73-8.75(1H), δ=9.37(2H).
[0024] Figure 2 Here is the fluorescence spectrum of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate:
[0025] Figure 2 The results showed that the fluorescence intensity of the (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate compound was the highest, reaching approximately 3.5 × 10⁻⁶, when the excitation wavelength was 330 nm. 4 . Specific Implementation
[0026] The raw materials involved in this invention are all existing products, and the specific preparation operations and testing methods are all conventional methods. The technical solution of this invention will be further described below with reference to specific embodiments.
[0027] Synthesis example
[0028] Example 1: First, 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid were added sequentially to a single-necked flask. The mixture was refluxed at 30°C for 24 hours to obtain a clear, brownish-brown solution, which was sodium 1,4-naphthalenedicarboxylic acid solution. Next, 8 mL of 1,3-dibromopropane, 12 mL of N-methylimidazolium, and 50 mL of acetone were added sequentially to a three-necked flask. The mixture was stirred and refluxed at 45°C for 20 hours, washed three times with 50 mL of acetone each time, and filtered to obtain a white solid powder. Finally, the prepared sodium 1,4-naphthalenedicarboxylic acid solution and 8.3 g of the white solid product obtained in the previous step were added sequentially to a single-necked flask. The mixture was stirred and reacted at 50°C for 24 hours. The prepared solution was rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylic acid salt, with a yield of 97.4%.
[0029] Example 2: First, 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid were added sequentially to a single-necked flask. The mixture was refluxed at 30°C for 24 hours to obtain a clear, brownish-yellow solution, which was a sodium 1,4-naphthalenedicarboxylic acid solution. Next, 8 mL of 1,3-dibromopropane, 12 mL of N-methylimidazolium, and 50 mL of acetone were added sequentially to a three-necked flask. The mixture was stirred and refluxed at 45°C for 20 hours, washed three times with 50 mL of acetone each time, and filtered to obtain a white solid powder. Finally, the prepared sodium 1,4-naphthalenedicarboxylic acid solution and 8.3 g of the white solid product obtained in the previous step were added sequentially to a single-necked flask. The mixture was stirred and reacted at 40°C for 12 hours. The prepared solution was rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylic acid salt, with a yield of 57.8%.
[0030] Example 3: First, 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid were added sequentially to a single-necked flask. The mixture was refluxed at 30 °C for 24 hours to obtain a clear, brownish-yellow solution, which was sodium 1,4-naphthalenedicarboxylic acid solution. Next, 8 mL of 1,3-dibromopropane, 12 mL of N-methylimidazole, and 50 mL of acetone were added sequentially to a three-necked flask. The mixture was stirred and refluxed at 45 °C for 20 hours, washed three times with 50 mL of acetone each time, and filtered to obtain a white solid powder. Finally, the prepared 1,4-... The sodium diformate solution and 8.3 g of the white solid product obtained in the previous step were stirred at 30 °C for 36 h. The prepared solution was rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate, with a yield of 45.2%.
[0031] Example 4: First, 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid were added sequentially to a single-necked flask. The mixture was refluxed at 30°C for 24 hours to obtain a clear, brownish-brown solution, which was sodium 1,4-naphthalenedicarboxylic acid solution. Next, 8 mL of 1,3-dibromopropane, 12 mL of N-methylimidazolium, and 50 mL of acetone were added sequentially to a three-necked flask. The mixture was stirred and refluxed at 45°C for 20 hours, washed three times with 50 mL of acetone each time, and filtered to obtain a white solid powder. Finally, the prepared sodium 1,4-naphthalenedicarboxylic acid solution and 8.3 g of the white solid product obtained in the previous step were added sequentially to a single-necked flask. The mixture was stirred and reacted at 25°C for 48 hours. The prepared solution was rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylic acid, with a yield of 37.2%.
[0032] Fluorescence test example
[0033] Example 7: An aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate with a concentration of 4 mmol / L was prepared. Fluorescence was measured at an excitation wavelength of 330 nm, and the fluorescence intensity was found to be approximately 3.5 × 10⁻⁶. 4 au, with an emission wavelength of 375nm.
[0034] Example 8: An aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate with a concentration of 4 mmol / L was prepared. Fluorescence was measured at an excitation wavelength of 310 nm, and the fluorescence intensity was found to be almost zero, with no emission wavelength.
[0035] Example 9: An aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate with a concentration of 6 mmol / L was prepared. Fluorescence was measured at an excitation wavelength of 330 nm, and the fluorescence intensity was found to be approximately 3.0 × 10⁻⁶. 4 au, with an emission wavelength of 375nm.
[0036] Example 10: An aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate with a concentration of 2 mmol / L was prepared. Fluorescence was measured at an excitation wavelength of 330 nm, and the fluorescence intensity was found to be approximately 2.8 × 10⁻⁶. 4 au, with an emission wavelength of 375nm.
[0037] Example 11: An aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate with a concentration of 10 mmol / L was prepared. Fluorescence was measured at an excitation wavelength of 330 nm, and the fluorescence intensity was found to be approximately 2.0 × 10⁻⁶. 4au, with an emission wavelength of 375nm.
[0038] Example 12: Preparation of (poly)1,3-di(N-methylimidazolyl)propane 1,4- at a concentration of 1 mmol / L. An aqueous solution of dicarboxylate was used. Fluorescence was measured at an excitation wavelength of 330 nm, and the measured fluorescence intensity was approximately 1.6 × 10⁻⁶. 4 au, with an emission wavelength of 360nm.
[0039] Examples of analysis and identification of nitrophenols
[0040] In Example 13, 0.01 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm, and the fluorescence was quenched by about 14.3%.
[0041] Example 14: In a solution of (poly)1,3-di(N-methylimidazolyl)propane at a concentration of 4 mmol / L, 1,4- When o-hydroxyphenol at a concentration of 0.01 mmol / L was added to an aqueous solution of diformate, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm, the fluorescence intensity decreased by approximately 7.1%.
[0042] In Example 15, 0.05 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 42.9%.
[0043] In Example 16, 0.05 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 28.6%.
[0044] In Example 17, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 71.4%.
[0045] In Example 18, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by about 35.7%.
[0046] Example 19: In a solution of (poly)1,3-di(N-methylimidazolyl)propane at a concentration of 4 mmol / L, 1,4- When 0.5 mmol / L p-nitrophenol was added to an aqueous solution of diformate to adjust the pH to 7, the excitation wavelength was set to 330 nm, and the emission wavelength was set to 375 nm. The fluorescence intensity decreased by approximately 100%.
[0047] In Example 20, 0.5 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 7, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 82.3%.
[0048] In Example 21, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 4, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm, and the fluorescence intensity decreased by about 60%.
[0049] In Example 22, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 4, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 34.2%.
[0050] In Example 23, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 6, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 71.4%.
[0051] In Example 24, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 6, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 38.6%.
[0052] In Example 25, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 8, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 82.9%.
[0053] In Example 26, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 8, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by about 38.5%.
[0054] In Example 27, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 10, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 82.9%.
[0055] In Example 28, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 10, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 28.6%.
[0056] In Example 29, 0.1 mmol / L of p-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 12, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 85.7%.
[0057] In Example 30, 0.1 mmol / L o-nitrophenol was added to an aqueous solution of (poly)1,3-di(N-methylimidazolyl)propane 1,4-naphthalenedicarboxylate at a concentration of 4 mmol / L, the pH was adjusted to 12, the excitation wavelength was 330 nm, and the emission wavelength was 375 nm. The fluorescence intensity decreased by approximately 25.7%.
Claims
1. Use of a fluorescent ionic liquid for the detection of nitrophenol isomers, characterized in that, The fluorescent ionic liquid is a compound (poly)1,3-bis(N-methylimidazolyl)propane-1,4-naphthalenedicarboxylate, and the structural unit of the compound is shown below: 。 2. The method for preparing the fluorescent ionic liquid according to claim 1, characterized in that, The method is as follows: First, 30 mL of NaOH solution (3 mol / L) and 9.47 g of 1,4-naphthalenedicarboxylic acid are added sequentially to a single-necked flask. The mixture is refluxed at 30 °C for 24 h to obtain a clear, brownish-brown solution, yielding a sodium 1,4-naphthalenedicarboxylic acid solution. Second, 8 mL of 1,3-dibromopropane, 12 mL of N-methylimidazolium, and 50 mL of acetone are added sequentially to a three-necked flask. The mixture is stirred and refluxed at 45 °C for 20 h, washed three times with 50 mL of acetone each time, and filtered to obtain a white solid powder. Finally, the prepared sodium 1,4-naphthalenedicarboxylic acid solution and 8.3 g of the obtained white solid product are added sequentially to a single-necked flask. The mixture is stirred and reacted at 25-50 °C for 12-48 h. The prepared solution is rotary evaporated, dried, diluted with anhydrous ethanol, filtered, and dried to obtain the target product (poly)1,3-di(N-methylimidazolyl)propane 1, 4-Naphthalenedicarboxylate.
3. The fluorescent ionic liquid as described in claim 1, characterized in that, The fluorescent ionic liquid contains a bisnaphthalene ring structure, which serves as a fluorescent probe for analyzing and identifying p-nitrophenol and o-nitrophenol isomers. When nitrophenol and o-nitrophenol isomers are added to an aqueous solution containing the fluorescent ionic liquid, the fluorescence of the fluorescent ionic liquid is quenched.