Preparation method and application of fluorescent ionic liquid containing binaphthyl structure

Abstract

The application relates to a preparation method of a fluorescent ionic liquid 3-methyl-1-naphthylmethyl imidazole naphthalene formate (NAIm) compound containing a double naphthalene ring structure, and the compound structure is shown in the following formula: the preparation method is as follows: tetrahydrofuran, 1-chloromethylnaphthalene and N-methyl imidazole are added into a three-necked flask, trifluoromethane is added after being heated to reflux under magnetic stirring for 16 hours, and the 3-methyl-1-naphthylmethyl imidazole chloride intermediate is obtained through purification treatment. Then, 1-naphthalene formic acid is added into NaOH aqueous solution, and the sodium 1-naphthalene formate solution is obtained through reaction at 30 DEG C for 24 hours. Finally, the obtained imidazole salt intermediate is added into the sodium 1-naphthalene formate solution, and the final product NAIm is obtained through purification treatment after reaction at 50 DEG C for 24 hours. The application is simple in operation, high in fluorescent intensity and sensitivity, and can be used as a fluorescent probe for detecting the organic pollutant nonylphenol in water.

Description

Technical Field

[0001] This invention relates to a method for preparing a fluorescent ionic liquid containing a bis-naphthalene ring structure. The compound has a bis-naphthalene ring structure and high fluorescence intensity and sensitivity, and can be used as a fluorescent probe to detect pollutants in water. Background Technology

[0002] Fluorescent ionic liquids are functionalized ionic liquids that possess both the characteristics of ionic liquids and certain fluorescence properties. Due to their unique physicochemical properties, such as good solubility, tunable photophysical properties, and ease of preparation, they exhibit great application potential in various fields. Existing technology provides a method for preparing the fluorescent ionic liquid 3-methyl-1-naphthylmethylimidazolium naphthate and the detection of the pollutant nonylphenol in water using this fluorescent ion. The prepared fluorescent ionic liquid exhibits advantages such as good stability, high fluorescence intensity, and high sensitivity.

[0003] Existing technology discloses a method for preparing and applying a fluorescent ionic liquid containing a binaphthalene ring structure. Naphthalene ring structures are introduced onto the anions and cations of the ionic liquid, respectively, improving the fluorescence intensity and sensitivity. Its application to the detection of nonylphenol, an organic pollutant in water, offers advantages such as simple operation, high sensitivity, and short response time. However, there are currently no reports on the use of fluorescent liquids for the detection of nonylphenol in water. Summary of the Invention

[0004] One objective of this invention is to provide a fluorescent ionic liquid containing a binaphthalene ring structure, wherein both the cation and anion structures of this compound possess a naphthalene ring structure, similar to mononaphthalene ring fluorescent ionic liquids, such as 1-butyl-3-methylimidazolium naphthate, 1-methyl-3-methylnaphthaleneimidazolium chloride, etc., or whose anion is tetrafluoroborate (BF4). - ), hexafluorophosphate (PF6) - ) or halogens (Cl - or Br - Compared to ionic liquids, it exhibits a stronger fluorescence effect, resulting in a significant increase in sensitivity during fluorescence detection.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A fluorescent ionic liquid containing a bisnaphthalene ring structure has the following chemical structure:

[0007]

[0008] This invention discloses the above-mentioned fluorescent ionic liquid containing a bis-naphthalene ring structure. Its process is simple, easy to scale up for mass production, requires little equipment investment, and is low in cost. The process includes the following steps:

[0009] Step 1: Tetrahydrofuran, 1-chloromethylnaphthalene and N-methylimidazolium were added to the same three-necked flask and refluxed at 70°C for 16 hours in a magnetically heated and stirred container. Then, chloroform was added and purified to obtain the imidazolium salt intermediate, 1-methyl-3-methylnaphthalene imidazolium chloride.

[0010] Step 2: Weigh NaOH into a beaker, add a small amount of water to prepare a 3 mol / L NaOH solution, and transfer the prepared NaOH solution into a single-necked flask; then weigh 1-naphthoic acid and add it to the NaOH solution (NaOH slightly in excess, the molar ratio of NaOH to 1-naphthoic acid is approximately 1.03:1), and react at 30℃ for 24 h to obtain a yellow sodium naphthoate solution.

[0011] Step 3: The imidazole salt intermediate 1-methyl-3-methylnaphthylimidazolium chloride was added to a sodium 1-naphthoate solution. The reaction was carried out at 50°C for 24 hours using a magnetic stirrer. Water was then removed by rotary evaporation, and the mixture was transferred to a beaker. Anhydrous ethanol was added, and the mixture was frozen for 3 hours before being removed and filtered. After purification, a fluorescent ionic liquid containing a binaphthalene ring structure, namely 3-methyl-1-naphthylmethylimidazolium naphthoate, was obtained.

[0012] The ionic liquid of this invention, a fluorescent ionic liquid containing a binaphthalene ring structure, is a deep yellow, viscous, maltose-like liquid with a product yield of 85.4%. The preparation principle of the 3-methyl-1-naphthylmethylimidazolium naphthate compound containing the binaphthalene ring structure is as follows:

[0013] Step 1: Principle of intermediate ionic liquid synthesis:

[0014]

[0015] Step 2: Principle of sodium naphthate synthesis:

[0016]

[0017] Step 3: Principle of final product synthesis

[0018]

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] ① This compound contains a naphthalene ring structure in both its cation and anion structures, and is similar to single-naphthalene ring fluorescent ionic liquids, such as 1-butyl-3-methylimidazolium naphthate, 1-methyl-3-methylnaphthalimidazolium chloride, etc., or its anion is tetrafluoroborate (BF4). - ), hexafluorophosphate (PF6) - ) or halogens (Cl - or Br -Compared to ionic liquids, it exhibits a stronger fluorescence effect, resulting in a significant increase in sensitivity during fluorescence detection.

[0021] ② This invention exhibits stronger fluorescence performance. The ethanol / water solution (10 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. 5 au, whose corresponding emission wavelength is 420nm.

[0022] ③ The preparation method of the bisnaphthyl ring fluorescent ionic liquid of the present invention is simple to operate, requires little equipment investment, and is easy to scale up and produce.

[0023] ④ The fluorescent ionic liquid of this invention has good environmental performance, with low volatility, no odor, and recyclability.

[0024] The preparation of the fluorescent ionic liquid 3-methyl-1-naphthylmethylimidazolium naphthate containing the binaphthyl ring structure of this invention broadens the application of fluorescent ionic liquids in the field of fluorescent probes and their application in fluorescence detection research. Attached Figure Description

[0025] The following diagram is provided to further illustrate the structure and performance of the product.

[0026] Figure 1 This is the 1H NMR spectrum of a fluorescent ionic liquid containing a bisnaphthalene ring structure:

[0027] 1 H NMR (400MHz, DMSO) δ (ppm) = 9.88 (s, 1H), 8.74 (m, 1H), 7.78 (d, 1H, J = 8.0Hz), 7.67 (m, 2H), 7.35-7.55 (t, 1H, J = 4.0H z), 7.48 (d, 1H, J = 8.0Hz), 7.16 (m, 5H), 7.03-6.93 (s, 2H), 6.90 (s, 1H), 6.80-6.78 (m, 3H), 6.60 (s, 1H), 3.56 (s, 3H)

[0028] Figure 2 This is the fluorescence spectrum of a fluorescent ionic liquid containing a bisnaphthalene ring structure:

[0029] Figure 2 The results showed that 3-methyl-1-naphthylmethylimidazolium naphthate exhibited fluorescence in all insoluble solvents when excited at a wavelength of 330 nm. The strongest fluorescence (3.5 × 10⁻⁶) was observed in a mixture of ethanol and water (1:9). 5 au.

[0030] Figure 3This is a comparison diagram of adding nonylphenol to a fluorescent ionic liquid solution containing a bisnaphthalene ring structure.

[0031] Figure 3 This indicates that the fluorescent ionic liquid solution containing the bisnaphthalene ring structure has a certain degree of fluorescence. When nonylphenol is added to it, its fluorescence weakens, that is, a certain degree of fluorescence quenching occurs.

[0032] Figure 4 It is the fluorescence spectrum of a fluorescent ionic liquid solution containing a bisnaphthalene ring structure after the addition of nonylphenol.

[0033] Figure 4 This indicates that adding different concentrations of nonylphenol to a fluorescent ionic liquid solution containing a bisnaphthalene ring structure results in varying degrees of quenching of its fluorescence. Specific Implementation

[0034] 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.

[0035] Synthesis example

[0036] In Example 1, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of chloroform was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and chloroform were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was reacted at 40 °C for 24 h in a magnetic stirrer. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 73.2%.

[0037] In Example 2, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of chloroform was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and chloroform were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was stirred at 50 °C for 24 h in a magnetic stirrer. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 82.3%.

[0038] In Example 3, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of chloroform was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and chloroform were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was stirred at 60 °C for 24 h in a magnetic stirrer. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 83.2%.

[0039] In Example 4, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of trifluoromethane was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and trichloromethane were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer under constant temperature to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was stirred at 60 °C for 24 h in a magnetic stirrer under constant temperature. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 75.2%.

[0040] In Example 5, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of trifluoromethane was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and trichloromethane were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was stirred at 50 °C for 12 h in a magnetic stirrer. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 65.6%.

[0041] In Example 6, 20 mL of tetrahydrofuran, 3.6 g (20 mmol) of 1-chloromethylnaphthalene, and 1.66 g (20 mmol) of N-methylimidazole were added to a 100 mL three-necked flask. The mixture was refluxed at 70 °C for 16 h using a magnetic stirrer. Then, 15 mL of chloroform was added, and the mixture was shaken to form a homogeneous phase. The tetrahydrofuran and chloroform were then removed by rotary evaporation, followed by rinsing with 10 mL of tetrahydrofuran. After drying, 1-methyl-3-methylnaphthaleneimidazole chloride was obtained. Next, 0.8 g (20 mmol) of sodium hydroxide was weighed into a beaker, and 6.7 mL of distilled water was added and shaken to prepare a 3 mol / L sodium hydroxide solution as the solvent. The prepared solution was then transferred to a single-necked flask for later use. 3.344 g (19.42 mmol) of 1-naphthoic acid was weighed and added to a prepared sodium hydroxide solution (slight excess sodium hydroxide was used to ensure a complete reaction; the specific ratio was 1.03:1 molar ratio of sodium hydroxide to 1-naphthoic acid). The system was reacted at 30 °C for 24 h in a magnetic stirrer to obtain a sodium 1-naphthoate solution. Finally, 1-methyl-3-methylnaphthoimidazole chloride was added to the sodium 1-naphthoate solution, and the system was stirred at 50 °C for 36 h in a magnetic stirrer. After removing water by rotary evaporation, the product was transferred to a beaker. 10 mL of anhydrous ethanol was added to the solution and shaken well. The system was then frozen for 3 h, filtered, rotary evaporated, washed, and dried to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate, with a yield of 85.4%.

[0042] Fluorescence test example

[0043] Example 7: An ethanol solution of 3-methyl-1-naphthylmethylimidazolium naphthol with a concentration of 100 mmol / L was prepared and diluted with water to a concentration of 10 mmol / L. 200 μL of the 10 mmol / L ethanol / water solution of 3-methyl-1-naphthylmethylimidazolium naphthol was taken and fluorescence was measured at an excitation wavelength of 330 nm. The measured fluorescence intensity was 3.5 × 10⁻⁶. 5 au, with an emission wavelength of 420nm.

[0044] Example 8: An ethanol solution of 3-methyl-1-naphthylmethylimidazolium naphthol with a concentration of 100 mmol / L was prepared and diluted with ethanol to a concentration of 10 mmol / L. 200 μL of the 10 mmol / L ethanol solution of 3-methyl-1-naphthylmethylimidazolium naphthol was taken and fluorescence was measured at an excitation wavelength of 330 nm. The measured fluorescence intensity was 7.5 × 10⁻⁶. 4 au, with an emission wavelength of 360nm.

[0045] Example 9: An aqueous solution of 3-methyl-1-naphthylmethylimidazolium naphthol with a concentration of 100 mmol / L was prepared and diluted with ethanol to a concentration of 10 mmol / L. 200 μL of the 10 mmol / L aqueous / ethanol solution of 3-methyl-1-naphthylmethylimidazolium naphthol was taken and its fluorescence was measured at an excitation wavelength of 330 nm. The measured fluorescence intensity was 5.0 × 10⁻⁶. 4 au, with an emission wavelength of 360nm.

[0046] Example 10: An aqueous solution of 3-methyl-1-naphthylmethylimidazolium naphthol was prepared with a concentration of 100 mmol / L and diluted with water to a concentration of 10 mmol / L. 200 μL of the 10 mmol / L aqueous solution of 3-methyl-1-naphthylmethylimidazolium naphthol was taken and fluorescence was measured at an excitation wavelength of 330 nm. The measured fluorescence intensity was 5.0 × 10⁻⁶. 4 au, with an emission wavelength of 420nm.

[0047] Nonylphenol detection example

[0048] Example 11: In a 10 mmol / L ethanol / water solution (1:9) of 3-methyl-1-naphthylmethylimidazolium naphthate, the addition of 1 μmol / L nonylphenol resulted in a fluorescence intensity that increased from 3.5 × 10⁻⁶ to [the original value missing]. 5 au decreased to 3.25 × 10 5 au.

[0049] Example 11: In a 10 mmol / L ethanol / water solution (1:9) of 3-methyl-1-naphthylmethylimidazolium naphthate, the addition of 10 μmol / L nonylphenol resulted in a fluorescence intensity that increased from 3.5 × 10⁻⁶ to [the original value missing]. 5 au decreased to 2.75 × 10 5 au.

[0050] Example 12: In a 10 mmol / L ethanol / water solution (1:9) of 3-methyl-1-naphthylmethylimidazolium naphthate, the addition of 100 μmol / L nonylphenol resulted in a fluorescence intensity that increased from 3.5 × 10⁻⁶ to [the original value missing]. 5 au decreased to 1.85 × 10 5 au.

[0051] Example 13: In a 10 mmol / L ethanol / water solution (1:9) of 3-methyl-1-naphthylmethylimidazolium naphthate, the addition of 200 μmol / L nonylphenol resulted in a fluorescence intensity that increased from 3.5 × 10⁻⁶ to [the original value missing]. 5 au decreased to 1.75 × 10 5 au.

Claims

1. A fluorescent ionic liquid containing a bisnaphthalene ring structure, characterized in that, The ionic liquid is the compound 3-methyl-1-naphthylmethylimidazolium naphthate, whose structure is shown below: 。 2. The method for preparing a fluorescent ionic liquid containing a bis-naphthalene ring structure as described in claim 1, characterized in that, The method is as follows: Tetrahydrofuran, 1-chloromethylnaphthalene, and N-methylimidazolium were added to a three-necked flask and refluxed at 70 °C for 16 h with a magnetic stirrer. Then, chloroform was added, and after purification, the intermediate 1-methyl-3-methylnaphthaleneimidazolium chloride was obtained. Next, 1-naphthoic acid was added to an aqueous sodium hydroxide solution and reacted at 30 °C for 24 h to obtain a sodium 1-naphthoate solution. Finally, the obtained intermediate 1-methyl-3-methylnaphthoate chloride was added to the sodium 1-naphthoate solution and reacted at 50 °C for 24 h to obtain the product 3-methyl-1-naphthomethylimidazolium naphthoate.

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