A colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions, and its preparation method and application

Abstract

The present application provides a colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions, and its preparation method and application. The colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions is a Schiff base probe with dicyanoisophorone and pyridine carboxyhydrazide as fluorescent groups, and its structural formula is shown in Formula I. The probe of the present invention can realize dual-channel sensing detection of aluminum ions through changes in fluorescence spectrum and color, and can perform real-time qualitative and quantitative visual colorimetric detection. In addition, the probe of the present invention has good specificity, strong anti-interference ability to other metal ions, low detection limit, and fluorescence detection limit as low as 4.01×10 ‑8 M, the UV detection limit is as low as 6.41×10 ‑7 M. #imgabs0#

Description

Technical Field

[0001] The present application relates to the technical field of fluorescent probes, and more specifically, to a colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions, and a preparation method and application thereof. Background Art

[0002] Aluminum ranks third in the Earth's crust, after oxygen and silicon. Aluminum is not only one of the most abundant metal elements in the Earth's crust, but is also widely present in water, soil, the atmosphere, and in living organisms such as plants and animals. Its compounds are also widely used in water treatment, pharmaceuticals, food additives, and the production of light alloys. As a non-essential element for the human body, excessive aluminum accumulation in various tissues and organs can cause various diseases, such as microcytic hypochromic anemia, aluminum-related bone diseases, encephalopathy, myopathy, dementia, and Alzheimer's disease. Furthermore, trivalent aluminum ions are widely present in many plant and animal tissues and in natural water systems. Excessive aluminum ions can lead to fish extinction and reduced agricultural yields.

[0003] Current methods for metal ion detection include inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectroscopy (AAS), electrochemical methods, and voltammetry. However, these methods require expensive and complex instrumentation and specialized technicians, and have drawbacks such as cumbersome analysis, long analysis times, and high costs. These methods cannot meet the requirements for rapid on-site evaluation required by modern environmental monitoring. In recent years, fluorescence detection and analysis methods based on chemical sensors have attracted particular attention due to their simplicity, high selectivity and sensitivity, low detection limits, fast analysis times, non-destructiveness to samples, and convenient visual qualitative identification.

[0004] However, although many molecular probes for recognizing aluminum ions have been reported, these probes have problems such as cumbersome synthesis steps, low selectivity and sensitivity, which reduce the applicability of the probes. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present application provides a colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions, as well as its preparation method and application. The probe of the present invention can achieve dual-channel sensing detection of aluminum ions through changes in fluorescence spectrum and color, and can perform real-time qualitative and quantitative visual colorimetric detection. In addition, the probe of the present invention has good specificity, strong anti-interference ability for other metal ions, and a low detection limit, with a fluorescence detection limit as low as 4.01×10 -8 M, the UV detection limit is as low as 6.41×10 -7 M.

[0006] In order to achieve the above objectives, in the first aspect, the present application provides a colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions. The colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions is a Schiff base probe with dicyanoisophorone and pyridine carboxyhydrazide as fluorescent groups, and its structural formula is shown in Formula I:

[0007]

[0008] In a second aspect, the present application provides a method for preparing the above-mentioned colorimetric-fluorescent dual-channel molecular probe for recognizing aluminum ions, comprising the following steps:

[0009] Step 1, preparing compound I using isophorone and malononitrile as reaction raw materials;

[0010] Step 2, reacting compound I with p-hydroxybenzaldehyde to prepare compound II;

[0011] Step 3, reacting compound II with hexamethylenetetramine to prepare compound III;

[0012] Step 4: reacting compound III with 2-pyridinecarboxylic acid hydrazide to obtain the target product;

[0013] The reaction route is as follows:

[0014]

[0015] Furthermore, the preparation method of compound I in step 1 is to dissolve isophorone in anhydrous ethanol, then add malononitrile and piperidine in sequence, and heat, stir and reflux under a nitrogen atmosphere; after the reaction is completed, cool to room temperature, pour the reaction solution into water to generate a large amount of precipitate, and separate and purify the solid obtained by filtration by column chromatography.

[0016] Preferably, in the preparation method of compound I in step 1, the molar ratio of isophorone to malononitrile is 5:6.

[0017] More preferably, the amount of isophorone added is 50.1 mmol, the amount of malononitrile added is 60.1 mmol, the amount of piperidine added is 3 mol, and the reaction time is 6 h.

[0018] Furthermore, the preparation method of compound II in step 2 is to add p-hydroxybenzaldehyde to anhydrous ethanol, and then add compound I and piperidine in sequence, heating and reflux until the raw material point disappears, and then stop the reaction; the reaction solution is dried and the obtained product is separated and purified by column chromatography.

[0019] Preferably, the molar ratio of compound I to p-hydroxybenzaldehyde is 1:1.

[0020] More preferably, the amount of compound I added is 10.5 mmol, the amount of p-hydroxybenzaldehyde added is 10.2 mmol, and the amount of piperidine added is 3.0 mmol.

[0021] Furthermore, the preparation method of compound III in step 3 is to dissolve compound II in trifluoroacetic acid, then add hexamethylenetetramine, and heat to reflux for reaction; after the reaction is completed, cool to room temperature, then slowly pour the reaction solution into water, filter the obtained product, and separate and purify it by column chromatography.

[0022] Preferably, the molar ratio of compound II to hexamethylenetetramine in step 3 is 1:1.

[0023] More preferably, the added amounts of compound II and hexamethylenetetramine in step 3 are both 1.5 mmol.

[0024] Furthermore, the preparation method of the target product in step 4 is to add compound III to ethanol, then add 2-pyridinecarboxylic acid hydrazide, and heat to reflux reaction; after stopping the reaction, cool to room temperature, a large amount of precipitate is generated, filter, and the obtained filter cake is purified by beating with ethanol.

[0025] Preferably, in step 4, the molar ratio of compound III to 2-pyridinecarboxylic acid hydrazide is 1:1.1.

[0026] More preferably, the amount of compound III added is 100 mg, and the reaction is heated under reflux for 4-8 hours.

[0027] In a third aspect, the present application provides the above-mentioned colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions for sensing and detecting the content of aluminum ions in a water environment system.

[0028] Furthermore, the sensing detection includes fluorescence detection, ultraviolet ratio detection, visual qualitative detection and reversible detection.

[0029] The technical solution provided by this application has at least the following beneficial effects compared to the existing technology:

[0030] 1) The synthesis method of the probe of the present invention only requires four steps to complete, the raw materials are economical and readily available, and the post-processing process is simple;

[0031] 2) The present invention enables dual-channel sensing of aluminum ions using both fluorescence spectral and color changes. The probe provided by the present invention can detect solution color changes under sunlight and fluorescence color changes under 365nm ultraviolet light. Therefore, the probe can quantitatively detect ultraviolet ratios using ultraviolet spectroscopy, making it a fluorescent probe with chromogenic sensing capabilities.

[0032] 3) The probe of the present invention has good specificity, strong anti-interference ability to other metal ions, and low detection limit. The detection limit of aluminum ion fluorescence is 4.01×10 -8 M, the UV detection limit was 6.41×10 -7 Based on its specificity, the probe of the present invention can be used as a specific indicator for the colorimetric-fluorescent dual-channel detection of the presence of aluminum ions in aqueous solutions, enabling real-time qualitative and quantitative visual colorimetric detection. Furthermore, the present invention enables rapid, reversible, and repeatable detection of aluminum ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The fluorescence spectra of the probe prepared in Example 2 for different metal ions under DMF / H2O are shown;

[0034] Figure 2 The effect of coexisting ions on the determination of aluminum ions;

[0035] Figure 3 The probe prepared in Example 2 was tested for different concentrations of Al 3+ Fluorescence spectrum response diagram of

[0036] Figure 4 The probe prepared in Example 2 was tested for different concentrations of Al 3+ UV spectral response diagram;

[0037] Figure 5 This is a diagram showing the color change of the probe prepared in Example 2 under sunlight after adding aluminum ions;

[0038] Figure 6 The fluorescence emission graphs of the probes prepared in Example 2 after adding aluminum ions under a UV lamp at 365 nm are shown;

[0039] Figure 7 This is a diagram showing the reversible changes in the recognition of aluminum ions by the probe prepared in Example 2. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to understand the present application more clearly, the present application is further described in detail below in conjunction with examples and drawings. However, it should be understood that the following examples are only preferred implementation methods of the present application, and the scope of protection required by the present application shall be based on the scope defined in the claims.

[0041] In the description of the present invention, it should be noted that if specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0042] <Example>

[0043] Example 1

[0044] A colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions. The colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions is a Schiff base probe with dicyanoisophorone and pyridine carboxyhydrazide as fluorescent groups, and its structural formula is shown in Formula I:

[0045]

[0046] Example 2

[0047] The preparation method of the colorimetric-fluorescent dual-channel molecular probe for recognizing aluminum ions described in Example 1 has the following reaction scheme:

[0048]

[0049] The steps include:

[0050] Step 1. Compound I was prepared using isophorone and malononitrile as reaction raw materials. Specifically, 6.91 g of isophorone (50.1 mmol) was dissolved in 100 mL of anhydrous ethanol, followed by the addition of 3.84 g of malononitrile (60.1 mmol) and 0.3 mL of piperidine (3.0 mmol). The mixture was heated, stirred, and refluxed under a nitrogen atmosphere for 6 h. The reaction was stopped after the complete reaction of isophorone was monitored by TLC. The reaction was allowed to stand and cool to room temperature, and the reaction solution was then poured into 200 mL of ice water to generate a large amount of off-white precipitate. The solid obtained by filtration was separated and purified by column chromatography to obtain 7.23 g of a white crystalline solid, namely, Compound I.

[0051] Step 2: Compound I is reacted with p-hydroxybenzaldehyde to prepare Compound II; specifically, p-hydroxybenzaldehyde (10.2 mmol) is added to a round-bottom flask containing 40 mL of anhydrous ethanol, followed by the addition of 10.5 mmol of Compound I and 3.0 mmol of piperidine, and the mixture is heated under reflux until the TLC plate detects the disappearance of the raw material spot, and the reaction is stopped; the reaction solution is spin-dried to obtain a product which is separated and purified by column chromatography to obtain Compound II;

[0052] Step 3: Compound II is reacted with hexamethylenetetramine to prepare compound III. Specifically, compound II (1.5 mmol) is dissolved in 10 mL of trifluoroacetic acid, and then 1.5 mmol of hexamethylenetetramine is added. The mixture is heated to reflux and the reaction is stopped after monitoring the completion of the reaction by TLC. The reaction solution is cooled to room temperature and then slowly poured into 50 mL of ice water. The product obtained by filtration is separated and purified by column chromatography to obtain compound III.

[0053] Step 4: Compound III is reacted with 2-pyridinecarboxylic acid hydrazide to obtain the target product. Specifically, 100 mg of compound III is added to a round-bottom flask containing 20 mL of ultra-dry ethanol, followed by the addition of 1.1 equivalents of compound III in 2-pyridinecarboxylic acid hydrazide. The mixture is heated under reflux for 4-8 hours until the reaction is complete as monitored by TLC. The reaction is stopped and the reaction liquid is cooled to room temperature. A large amount of precipitate is generated, which is filtered and the filter cake is purified by beating with ethanol to obtain the target product - a colorimetric-fluorescent dual-channel molecular probe for recognizing aluminum ions.

[0054] Application of colorimetric-fluorescent dual-channel molecular probe for aluminum ion recognition

[0055] 1. Fluorescence detection of aluminum ions using a colorimetric-fluorescent dual-channel molecular probe for aluminum ion recognition

[0056] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, after adding different metal ions, the fluorescence intensity change was detected by fluorescence spectrophotometer to detect its fluorescence selectivity for different metal ions. The test results are as follows Figure 1 As shown, Figure 1 L represents the probe. Figure 1 It can be seen that the probe itself has weak fluorescence at 580nm under 430nm wavelength excitation; after adding aluminum ions, the maximum fluorescence emission wavelength red-shifts to 620nm, and the fluorescence intensity is significantly enhanced; other metal ions (Fe 3+ 、Na + 、Fe 2+ 、Hg 2+ 、Ni 2+ , K + 、Cd 2+ Mg 2+ , Ca 2+ 、Ba 2+ 、Ag + 、Co 2+ 、Zn 2+ Cr 3+ 、Cu 2+ , Pb 2+ 、Mn 2+ ) had almost no effect on the fluorescence intensity.

[0057] To further confirm that the probe's selectivity for aluminum ions was not affected by the coexistence of other metal ions, a competitive fluorescence experiment was conducted. Figure 2 shown. Figure 2 The black color in the middle represents the fluorescence intensity of the probe (L in the figure) when a certain metal ion is added alone. The slash represents the fluorescence intensity of the probe (L in the figure) when aluminum ions are added and then other metal ions are added. Figure 2 Winning bid for "Al 3+ ” is 1.0×10 -5 mol / L is the fluorescence intensity of the system when aluminum ions exist alone, and the rest are the fluorescence intensities of the system when aluminum ions of the same concentration coexist with various metal ions of the same concentration multiples. Figure 2 It can be seen that Cu 2+ Due to its paramagnetic nature, the addition of Ni will quench the fluorescence. 2+ and Hg 2+ The addition of reduced the fluorescence intensity by about half, and the presence of other coexisting ions did not significantly change the detection results of the probe molecule for aluminum ions.

[0058] 2. Fluorescence detection of aluminum ion concentration using a colorimetric-fluorescent dual-channel molecular probe for aluminum ion recognition

[0059] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, different concentrations of aluminum ions were added to the solution, and the changes in the fluorescence absorption intensity were detected. The results are as follows Figure 3 shown. Figure 3 In (a), the abscissa is the wavelength (nm), the ordinate is the fluorescence intensity, and the excitation wavelength is 420 nm. Figure 3 It shows the aluminum ion concentration from 0 to 1×10 -5 Fluorescence intensity curve corresponding to mol / L. Figure 3 (b) shows the linear regression relationship between fluorescence intensity and aluminum ion concentration, Figure 3 (b) It can be seen that there is a good linear relationship between the change in fluorescence intensity and the concentration of added aluminum ions. Figure 3 (b) The UV detection limit can be as low as 4.01×10 -8 M, the probe of the present invention can realize the quantitative detection of aluminum ions.

[0060] 4. UV detection of aluminum ions using a colorimetric-fluorescent dual-channel molecular probe for aluminum ion recognition

[0061] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, detection of different concentrations of Al 3+ The UV absorption of the detected UV spectrum is shown in the figure below. Figure 4 As shown. Figure 4 In (a), the horizontal axis is the wavelength (nm) and the vertical axis is the ultraviolet absorption intensity. Figure 4 It shows the aluminum ion concentration from 0 to 5×10 -5 mol / L corresponding UV intensity curve. Figure 4 (b) shows the linear regression relationship between UV absorption intensity and aluminum ion concentration, Figure 4 (b) It can be seen that when the aluminum ion concentration is 5×10 -6 to 1.4×10 -5 mol / L range, the UV absorption intensity at 330nm changes with the added aluminum ion concentration and has a good linear relationship curve. Figure 4 (b) The UV detection limit can be as low as 6.41×10 -7 M, the probe of the present invention can realize the quantitative detection of aluminum ions.

[0062] 5. Colorimetric-fluorescent dual-channel molecular probe for aluminum ion detection under sunlight

[0063] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, add 5×10 -5 After adding mol / L aluminum ions, the color change under sunlight was detected. Figure 5 As shown, Figure 5 L represents the probe, Figure 5 The left side is without aluminum ions (i.e., only probe L), and the right side is with aluminum ions (i.e., probe L+Al 3+ ),Depend on Figure 5 It can be seen that after adding aluminum ions, the solution changes from yellow to red. The probe of the present invention can detect aluminum ions by visual colorimetry.

[0064] 6. Colorimetric-fluorescent dual-channel molecular probe for aluminum ion detection under ultraviolet irradiation

[0065] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, add 5×10 -5 After adding mol / L aluminum ions, place it under ultraviolet light at 365nm to observe the change in fluorescence color. Figure 6 shown. Figure 6 L represents the probe, Figure 6 The right side of the middle is without aluminum ions (i.e., only probe L), and the left side is with aluminum ions (i.e., probe L+Al 3+ ),Depend on Figure 6 It can be seen that after adding aluminum ions, the fluorescence color changes from no fluorescence to red fluorescence under 365nm ultraviolet light. The probe of the present invention can also achieve visual qualitative detection of aluminum ions under ultraviolet light.

[0066] VII. Reversible detection of aluminum ion recognition using a colorimetric-fluorescent dual-channel molecular probe

[0067] The aluminum ion colorimetric-fluorescent dual-channel molecular probe synthesized in Example 2 was dissolved in DMF / H2O (3 / 7, v / v) to a concentration of 1×10 -5 mol / L, add 5×10 -5 mol / L aluminum ions, and then the fluorescence was detected; then 1×10 -5 mol / L Na2EDTA and then detect the fluorescence. The results are as follows Figure 7 As shown in the figure, L represents the probe. 3+ To determine whether the detection is reversible, EDTA, a commonly used metal ion complexing agent, was selected for the experiment. Figure 7 It can be seen that the probe itself has almost no fluorescence intensity. When Al is added to the probe (10 μM) solution, 3+ After adding an equal amount of EDTA (10 μM), the fluorescence at 620 nm was enhanced, and after adding an equal amount of EDTA (10 μM), the fluorescence was quenched and returned to the state without adding Al. 3+ The intensity before, which shows that the probe is sensitive to Al 3+ The recognition of Al 3+ Replaced by EDTA, the probe detects Al 3+ Has good reversibility.

[0068] The above-mentioned specific embodiments of the present application are merely preferred embodiments for explaining the present application, and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications without creative contribution as needed. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing a colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions, characterized in that: The steps include: Step 1, preparing compound I using isophorone and malononitrile as reaction raw materials; Step 2, reacting compound I with p-hydroxybenzaldehyde to prepare compound II; Step 3, reacting compound II with hexamethylenetetramine to prepare compound III; Step 4: reacting compound III with 2-pyridinecarboxylic acid hydrazide to obtain the target product; The colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions is a Schiff base probe with dicyanoisophorone and pyridine carboxyhydrazide as fluorescent groups, and its structural formula is shown in Formula I: The reaction scheme is as follows:

2. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 1, characterized in that: The preparation method of compound I in step 1 is to dissolve isophorone in anhydrous ethanol, then add malononitrile and piperidine in sequence, and heat, stir and reflux under a nitrogen atmosphere; after the reaction is completed, cool to room temperature, pour the reaction solution into water to generate a large amount of precipitate, and separate and purify the solid obtained by filtration by column chromatography.

3. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 2, characterized in that: The molar ratio of isophorone to malononitrile is 5:

6.

4. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 1, characterized in that: The preparation method of compound II in step 2 is to add p-hydroxybenzaldehyde to anhydrous ethanol, then add compound I and piperidine in sequence, heat and reflux until the raw material point disappears, and then stop the reaction; the reaction solution is dried and the obtained product is separated and purified by column chromatography.

5. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 4, characterized in that: The molar ratio of compound I to p-hydroxybenzaldehyde is 1:

1.

6. The method for preparing a colorimetric-fluorescent dual-channel molecular probe for recognizing aluminum ions according to claim 1, wherein the preparation method of compound III in step 3 is to dissolve compound II in trifluoroacetic acid, then add hexamethylenetetramine, and heat under reflux for reaction; after the reaction is completed, the mixture is cooled to room temperature, and then the reaction solution is slowly poured into water, and the filtered product is separated and purified by column chromatography.

7. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 6, characterized in that: The molar ratio of compound II to hexamethylenetetramine is 1:

1.

8. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for identifying aluminum ions according to claim 1, characterized in that: The preparation method of the target product in step 4 is to add compound III to ethanol, then add 2-pyridinecarboxylic acid hydrazide, and heat to reflux for reaction; after stopping the reaction, cool to room temperature, a large amount of precipitate is generated, filter, and purify the obtained filter cake by beating with ethanol.

9. The method for preparing the colorimetric-fluorescent dual-channel molecular probe for recognizing aluminum ions according to any one of claims 1 to 8 is used for sensing and detecting the content of aluminum ions in a water environment system.

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