Compound for detecting aluminum ions

Abstract

The invention provides a compound for detecting aluminum ions, and particularly provides chromone-3-formaldehyde and 1H-imidazole-5-carbonyl (formula I) or salts thereof, and the compound has strong selectivity to aluminum ions, fast response time, macroscopic obvious fluorescence enhancement after complexation, and low detection limit.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent probe technology, and specifically relates to a compound for detecting aluminum ions. Background Technology

[0002] Aluminum is the third most abundant metallic element in the Earth's crust, following silicon and oxides. Nearly 8% of its composition exists in the atmosphere. Aluminum has wide applications in our daily lives, such as in food additives, water purification, kitchenware, and packaging materials. However, this widespread use does not mean it is harmless. More worryingly, excessive accumulation of aluminum in the human body can trigger a series of neurodegenerative diseases, including but not limited to Alzheimer's disease, Parkinson's disease, muscle atrophy, and memory and cognitive decline. The occurrence of these diseases is closely related to the toxic effects of aluminum compounds, suggesting that we must strictly control and manage it to protect our precious natural resources and human health. Therefore, the World Health Organization (WHO) recommends that the temporary tolerable intake of aluminum per week should not exceed 7 mg / kg body weight. Compared with these commonly used aluminum detection methods, fluorescence analysis has become the most attractive aluminum detection method due to its advantages of high sensitivity, good selectivity, real-time processing, simplicity, and fast response.

[0003] The selective and sensitive detection of metal ions using intelligent fluorescence tools has attracted considerable attention. Metal ions play various important roles in organisms and the environment. These roles often directly relate to human health and global pollution issues. Therefore, there is a strong need to develop innovative chemical sensing tools to monitor the concentration of these ions. Several conventional methods are available for identifying Al3+ ions, such as atomic absorption and emission spectrometry, inductively coupled plasma mass spectrometry, voltammetry, and electrochemical methods. However, these methods are generally considered complex, time-consuming, expensive, and unsuitable for rapid, field detection. For direct, practical field applications, a simple, low-cost, highly selective, and sensitive method would be useful. Interestingly, fluorescence-based sensing assays meet all the aforementioned requirements for the selective detection of biologically important metal ions. Summary of the Invention

[0004] Purpose of the invention: To address the problems existing in the prior art, the present invention provides a compound for detecting aluminum ions. This compound has high selectivity for aluminum ions, low detection limit, and short response time, and can rapidly detect trace amounts of aluminum ions in environmental systems.

[0005] On one hand, the present invention provides a compound or salt of Formula I: .

[0006] On the other hand, the present invention also provides a method for preparing the compound of formula I or a salt thereof, the method comprising the step of reacting 1H-imidazolium-5-carbazide with chromone-3-carboxaldehyde. .

[0007] In some embodiments, the molar ratio of 1H-imidazol-5-carbazide to chromone-3-carbaldehyde is 1:1 to 1:2, including 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2 or any value between the two numbers.

[0008] In some embodiments, the solvent used in the reaction of 1H-imidazolium-5-carbonylhydrazine with crromone-3-carbaldehyde is selected from protic solvents, such as methanol or ethanol.

[0009] In some embodiments, the reaction temperature of 1H-imidazol-5-carbonylhydrazide with chromone-3-carbaldehyde is selected from 50 to 90°C, including 50°C, 60°C, 70°C, 80°C, 90°C, or any two of these values. In some embodiments, the reaction temperature of 1H-imidazol-5-carbonylhydrazide with chromone-3-carbaldehyde is selected from 60 to 80°C.

[0010] In other embodiments, the method further includes the step of reacting methyl imidazole-4-carboxylate with hydrazine hydrate to form 1H-imidazole-5-carbonylhydrazine.

[0011] In some embodiments, the method includes the steps of reacting methyl imidazole-4-carboxylate with hydrazine hydrate to form 1H-imidazole-5-carbonylhydrazine, and the step of reacting 1H-imidazole-5-carbonylhydrazine with chromone-3-carbaldehyde. .

[0012] On the other hand, the present invention also provides the application of the compound of Formula I or a salt thereof in the preparation of a fluorescent probe for detecting aluminum ions in solution. .

[0013] On the other hand, the present invention also provides a method for detecting aluminum ions in a solution, the method comprising the steps of preparing a solution of a compound of Formula I or a salt thereof, adding it to a sample solution to be tested, and then performing detection on a fluorescence spectrometer and / or an ultraviolet spectrophotometer.

[0014] In some implementations, the fluorescence intensity of the fluorescence spectrometer is λ=496 nm.

[0015] In some embodiments, the excitation wavelength of the compound shown in Formula I is 404 nm. In some embodiments, the emission wavelength of the compound shown in Formula I is 496 nm.

[0016] In some embodiments, the solution of the compound shown in Formula I has a pH of 6-7.

[0017] In some implementations, the minimum detection limit for aluminum ions is 2.03 nM.

[0018] Salts of the compounds of this invention include, but are not limited to, hydrochloride salts.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages: This invention utilizes a one-step condensation method involving chromone-3-carboxaldehyde and 1H-imidazolium-5-carbazide to prepare a fluorescent probe with chromone-imidazolium as the parent compound. This fluorescent probe exhibits specific recognition of aluminum ions, a short response time, and high sensitivity, and is effective for detecting Al ions in solution. 3+ It exhibits high sensitivity, high selectivity and low detection limit (2.03 nM). More importantly, the probe preparation method is simple, the obtained product is a solid powder, which is easy to store and has good stability. Attached Figure Description

[0020] Figure 1 The aluminum ion fluorescent probe prepared in Example 1 was used to test different concentrations of aluminum ions (Al) in a (MeOH:Hepes) (v / v=9:1) solution. 3+ The ultraviolet absorption spectrum and color change diagram of () Figure 1 (The illustration shows colorless on the left and blue on the right).

[0021] Figure 2 The image shows the selective fluorescence spectra of the aluminum ion fluorescent probe prepared in Example 1 for different metal ions in a (MeOH:Hepes) (v / v=9:1) solution.

[0022] Figure 3 The fluorescent probe prepared in Example 1 was used in a (MeOH:Hepes) (v / v=9:1) solution to detect different concentrations of aluminum ions (Al). 3+ The fluorescence spectrum response diagram and color change diagram of ).

[0023] Figure 4 The image shows the fluorescence response of the fluorescent probe prepared in Example 1 to selective interference detection of different metal ions in a (MeOH:Hepes) (v / v=9:1) solution.

[0024] Figure 5 The fluorescent probe prepared in Example 1 reacts with aluminum ions (Al) in a mixture of (MeOH:Hepes) (v / v=9:1). 3+ Job-plot curve of complexation ratio.

[0025] Figure 6 The graph shows the response time of the fluorescent probe prepared in Example 1 when detecting aluminum ions.

[0026] Figure 7 The fluorescent probe prepared in Example 1 reacts with aluminum ions (Al) in a mixture of (MeOH:Hepes) (v / v=9:1). 3+ Fluorescence response diagrams at different pH values ​​(2 to 12).

[0027] Figure 8 The fluorescent test paper prepared using the fluorescent probe obtained in Example 1 shows the color change of aluminum ions at different concentrations.

[0028] Figure 9 The fluorescent probe prepared in Example 1 is based on RGB mode Al 3+ Linear calibration curve of concentration versus color intensity. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Unless otherwise specified, the experimental methods used in this invention are conventional methods. Unless otherwise specified, all materials and reagents used in the experiments are commercially available. All reagents used in the examples are commercially available analytical grade or chemically pure.

[0031] In the examples, the various metal ion solutions are prepared by adding deionized water to chloride salt chemical reagents with a purity of over 99%, such as anhydrous aluminum chloride, anhydrous ferric chloride, and zinc chloride. Example

[0032] The specific synthetic route of the fluorescent probe HBT based on chromone-3-carboxaldehyde: (1) Preparation of intermediate 1H-imidazolium-5-carbonylhydrazide In a 50 ml reaction flask containing 10 ml of methanol, methyl imidazole-4-carboxylate (0.252 g, 2 mmol) and hydrazine hydrate (0.15 g, 3 mmol) were added separately. After stirring to dissolve, the reaction system was heated to 65 °C and refluxed with stirring for 4 hours. After cooling the reaction solution to room temperature, the organic solvent was removed by vacuum distillation to obtain a crude product. The crude product was subjected to column chromatography (methanol:dichloromethane = 1:15) to give a yellow solid 1H-imidazolium-5-carbonylhydrazine (0.225 g, 90%).

[0033] The structural formula of the obtained intermediate 1H-imidazol-5-carbonylhydrazide is: .

[0034] 2) Preparation of aluminum ion fluorescent probe HBT based on chromone-3-formaldehyde matrix In a 50 ml round-bottom flask containing 5 ml of ethanol, 1H-imidazolium-5-carbazide (A) (0.126 g, 1 mmol) and chromone-3-carboxaldehyde (B) (0.174 g, 1 mmol) were added separately. After stirring to dissolve, the reaction system was heated to 80 °C and refluxed for 4 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction system was cooled to room temperature, and the solvent was removed by vacuum distillation. The crude product was purified by recrystallization (EtOH : H2O = 1 : 10) to obtain the yellow solid fluorescent probe molecule HBT (0.260 g, 92%).

[0035] The structural formula of the obtained fluorescent probe compound is: .

[0036] Example

[0037] The aluminum ion detection fluorescent probe HBT prepared in Example 1 was prepared into a 1 mM probe stock solution using DMSO. Each metal ion was prepared into a 3 mM metal ion stock solution using deionized water. 30 μL of the probe stock solution and 50 μL of the metal ion stock solution were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1), and the results were analyzed using a fluorescence spectrometer and a UV spectrophotometer. The maximum excitation wavelength of the fluorescent probe was found to be 404 nm, and the maximum emission wavelength was 496 nm. Specific test results are as follows: Take two cuvettes and add 3 mL of a mixed solution (MeOH:Hepes) (v / v=9:1) containing 30 μL of probe stock solution to each cuvette. Then add 50 μL of aluminum ion stock solution to one of the cuvettes and perform UV spectroscopy. Figure 1 As shown, the fluorescent probe itself exhibits almost no UV absorption at wavelength λ = 400 nm, but the UV absorption peak gradually increases upon the addition of aluminum ions; moreover, the addition of aluminum ions changes the color of the probe solution from colorless to pale yellow. These results indicate that the probe is sensitive to Al... 3+ It has high sensitivity and selectivity.

[0038] like Figure 2 The figure shows the selective fluorescence spectra of the aluminum ion detection fluorescent probe for various common metal ions. When 30 μL of probe stock solution and 50 μL of metal ion stock solution were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1), the experimental results showed that only with the addition of aluminum ions did the fluorescence intensity at 496 nm show a significant increase. Moreover, the fluorescence intensity was significantly better than that with the addition of other metal ions, indicating that the fluorescent probe of this invention has excellent selectivity for aluminum ions.

[0039] like Figure 3 As shown, the fluorescent probe for aluminum ion detection reacts to different concentrations of aluminum ions (Al). 3+ The fluorescence spectrum response diagram of HBT was obtained. 30 μL of probe stock solution and 0–100 μL (0, 1, 2, 3…10, 15…50, 60…100 μL) of aluminum ion solution (3 mM aluminum ion stock solution) were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1). The fluorescent probe itself showed almost no fluorescence in solution, but the fluorescence at 496 nm increased continuously with increasing aluminum ion concentration, i.e., the fluorescence intensity increased with increasing aluminum ion concentration, accompanied by a significant color change. This indicates that the probe HBT prepared in Example 1 of this invention, after complexing with aluminum ions, inhibited the rotation of the C=N double bond, thereby inhibiting electron transfer, thus demonstrating that probe HBT is a fluorescence-enhanced probe.

[0040] like Figure 4 The figure shows a bar chart of fluorescence intensity after the aluminum ion detection fluorescent probe reacts with aluminum ions in the presence of different interfering metal ions. 30 μL of probe stock solution and 50 μL of any other metal ion (Cu) were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1). + Co 2+ Pd 2+ Ni 2+ Cu 2+ Cr 3+ Cu + Mn 2+ Mg 2+ Ba 2+ Pd 2+ Sn 2+ Fe 2+ K + Ca 2+ Sr 2+ Na + Ag + and Cd 2+ ) stock solution, and finally add 50 μL of Al to the blank solution. 3+ The stock solution was tested for fluorescence intensity. The results showed that, except for diamagnetic copper, other metal ions did not significantly interfere with the recognition of aluminum ions by the zinc ion fluorescent probe of this invention, indicating that the probe prepared in this invention has good specificity.

[0041] like Figure 5 As shown, the relationship between the probe and Al was studied using the Job's plot method. 3+To determine the binding rate, a certain volume of probe stock solution (1 mM) and Al were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1). 3+ A stock solution (3 mM) was used to bring the total concentration of the aluminum ion detection fluorescent probe and aluminum ions to 50 μM. By varying the concentration ratio (the molar ratio of the aluminum ion detection fluorescent probe to aluminum ions was (1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1), the difference between the fluorescence intensity at 496 nm and the fluorescence intensity of the aluminum ion fluorescent probe combined with itself at that concentration was plotted against the proportion of ions in the total concentration. Figure 5 It can be seen that the ordinate reaches its highest value when the proportion of aluminum ions is 0.5, which confirms that the fluorescent probe forms a stable complex [HBT - Al] with aluminum ions in a 1:1 ratio. 3+ ].

[0042] like Figure 6 As shown, 30 μL of probe stock solution and 50 μL of Al were added to 3 mL of blank buffer (MeOH:Hepes) (v / v=9:1). 3+ In the stock solution, the fluorescence intensity of the probe rapidly increased to its peak and stabilized within 5 minutes. Furthermore, the fluorescence intensity of the probe remained essentially constant over the following 30 minutes, indicating that the probe is effective against Al. 3+ The detection is stable enough.

[0043] like Figure 7 As shown, the solutions containing probe HBT stock solution (10 μL) and [HBT-Al] were adjusted with 1 M HCl and 1 M NaOH, respectively. 3+ ] Stock solution (10 μL) of MeOH H2O solution (1 mL), wherein [HBT - Al 3+ The stock solutions were prepared by dissolving the probe and aluminum chloride in double-distilled water to concentrations of 10 μM and 50 μM, respectively, to achieve different pH variations. The fluorescence intensity of these two systems was then tested within different pH ranges. The probe HBT itself showed almost no fluorescence intensity in the pH range from 2 to 12, but [HBT-Al]... 3+ The fluorescence intensity (496 nm) of the system significantly increased within the pH range of 4.0–8.0, reaching its maximum at pH 7. [HBT-Al] 3+ Under strong conditions (pH < 3.0), the fluorescence signal is relatively weak, possibly because the complexation site of the fluorescent probe HBT is protonated, making it difficult to complex with aluminum ions. [HBT - Al] 3+Under alkaline conditions (pH > 9.0), the fluorescence signal gradually decreases, possibly due to the formation of Al(OH)3 precipitate, which reduces the [HBT - Al] level. 3+ [Concentration]. Therefore, the optimal pH range for HBT is 6-7. HBT has the ability to detect Al in biological environments. 3+ The ability.

[0044] like Figure 8 As shown, filter paper was immersed in a MeOH:Hepes (v / v=9:1) stock solution containing a fluorescent probe (1mM) for half an hour. The test strip was then removed and air-dried to obtain a dried test strip containing the probe. The test strip was then immersed in aluminum ion concentration solutions of 0.1mM, 0.5mM, 1mM, 1.5mM, and 3mM, respectively, for 30 minutes. After air-drying, the color change of the fluorescent test strip prepared with the fluorescent probe HBT solution was measured under ultraviolet light when testing for different concentrations of aluminum ions. This indicates that the color of the HBT probe changes with the aluminum ion concentration and that it can quantitatively detect trace aluminum ions in the environment in a solid state.

[0045] like Figure 9 As shown, AI based on RGB mode 3+ Linear calibration curves of concentration versus color intensity. 30 μL of probe stock solution and 0, 5, 15, 25, and 50 μL of aluminum ion solution (3 mM aluminum ion stock solution) were added to 3 mL of blank solution (MeOH:Hepes) (v / v=9:1). The experiment was conducted by capturing probe HBT and different concentrations of Al. 3+ High-resolution images of the solution under 365 nm ultraviolet light were obtained, and the images were converted into corresponding RGB data using a "Color Assist" app on a mobile phone. The color intensity was calculated using the formula I = 0.3R + 0.59G + 0.11B. The results showed that, within the range of 0-50 μM, the color intensity was similar to that of Al. 3+ There is a good linear relationship between concentrations.

[0046] The above experiments demonstrate that a fluorescent probe HBT with chromone-3-carboxaldehyde and 1H-imidazolium-5-carbazide as fluorescent groups can be prepared via a condensation reaction. This probe is effective against Al in solution. 3+ It exhibits high sensitivity and high selectivity.

Claims

1. A compound or salt thereof, characterized by, The structure is shown in the following formula I: .

2. A process for preparing a compound represented by the formula I or a salt thereof, characterized by, The method comprises a step of reacting 1 H-imidazole-5-carbohydrazide with chromone-3-carboxaldehyde, .

3. The method of claim 2, wherein, The method further comprises the step of reacting imidazole-4-carboxylic acid methyl ester with hydrazine hydrate to form 1H-imidazole-5-carbohydrazide.

4. The method according to claim 2 or 3, characterized in that, The molar ratio of 1H-imidazole-5-carbohydrazide to chromone-3-carboxaldehyde is 1:1 to 1:

2.

5. The method according to any one of claims 2-4, characterized in that, The solvent used for the reaction of 1H-imidazole-5-carbohydrazide with chromone-3-carboxaldehyde is selected from protic solvents, preferably methanol or ethanol.

6. The method according to any one of claims 2-5, characterized in that, The temperature for the reaction of 1H-imidazole-5-carbohydrazide with chromone-3-carboxaldehyde is selected from 50 to 90 °C, preferably 60 to 80 °C.

7. Use of the compound of claim 1 or a salt thereof for the preparation of a fluorescent probe for detecting aluminum ions in a solution.

8. A method of detecting aluminum ions in a solution, characterized by, The method comprises the steps of formulating the compound of claim 1 or a salt thereof into a solution, adding it to the sample solution to be detected, and subsequently detecting it in a fluorescence spectrometer and / or ultraviolet spectrophotometer.

9. The method of claim 8, wherein, The fluorescence intensity of the fluorescence spectrometer is λ = 496 nm.

10. The method according to claim 8 or 9, characterized in that, a solution of the compound of formula I at pH = 6-7, .

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