A naked-eye recognition, uv and fluorescent probe, preparation method and application thereof

Abstract

The application discloses a naked-eye identification, ultraviolet and fluorescent probe, a preparation method and application thereof. The probe is prepared from 5-methyl-2-aminopyridine and 5-chlorosalicylaldehyde as raw materials, a reducing agent is added after a period of reaction, and the probe can be obtained through purification. 3+ Fe 2+ and Ag + can be naked-eye identified under ultraviolet light. 3+ Fe + and Ag 3+ can be identified and detected by ultraviolet spectrum. 3+ Fe + content can be identified and detected by fluorescence spectrum. The probe is a small molecular compound, simple to synthesize, and has the advantages of good selectivity, high sensitivity, fast response, low detection limit and real-time detection, and has potential application in the identification and content detection of iron ions and silver ions in medicines, various water areas, soil and the like.

Description

Technical Field

[0001] This invention belongs to the field of probe technology, specifically relating to a naked-eye recognition, ultraviolet and fluorescent probe, its preparation method and its application. Background Technology

[0002] Iron and silver are important metallic elements with wide applications in pharmaceuticals, electroplating, water treatment, imaging, and electrical and electronic fields. Iron ions are among the most important metallic elements in living organisms, existing in various forms such as hemoglobin, iron-containing enzymes, ferritin, and hemosiderin. Silver possesses excellent physical, chemical, and broad-spectrum antibacterial properties, playing a vital role in industry and commerce, and is also important in the ecological environment. + The pollution mainly comes from industrial wastewater and waste residue. 3+ Fe 2+ Deficiency or Fe 3+ Fe 2+ Ag + Excessive amounts of Fe can cause serious harm to humans, animals, plants, and the ecological environment. Therefore, the use of Fe... 3+ Fe 2+ Ag + Rapid identification and accurate content detection are of great significance.

[0003] Currently, common methods for detecting metal ions include atomic absorption spectrometry, electrochemical methods, atomic fluorescence spectrometry, and electro-coupled plasma mass spectrometry. However, these methods generally suffer from drawbacks such as cumbersome sample processing, time consumption, and expensive instruments, which greatly limit their practical application, especially for most small and medium-sized enterprises, as they cannot implement detection in real time and conveniently.

[0004] Ultraviolet (UV) and fluorescence methods are widely used due to their advantages such as inexpensive instruments, simple operation, strong selectivity, high sensitivity, and fast speed. In addition, the naked-eye qualitative identification of metal ions by color change (under UV lamp or natural light), especially naked-eye identification under natural light without any instruments, is the most convenient, inexpensive, intuitive, time-saving, real-time, and on-site detection method for metal ions.

[0005] Many technologies capable of identifying Fe have already been developed. 3+ Ag + Fe 2 Ultraviolet probes and fluorescent probes are available, but the development of probes capable of simultaneously identifying Fe with the naked eye is needed. 3+ Ag + Fe 2 Or simultaneously, qualitative and quantitative detection of Fe using fluorescence. 3+ Ag + Highly selective, highly sensitive, rapid, multifunctional, and easily synthesized small molecule probes remain a challenge. Summary of the Invention

[0006] The purpose of this invention is to design a naked-eye recognition, ultraviolet and fluorescent probe, its preparation method and its application, which can simultaneously identify Fe. 3+ Ag + Fe 2 .

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first objective of this invention is to provide a naked-eye recognition, ultraviolet and fluorescent probe, the chemical name of which is 4-chloro-2-(((5-methylpyridin-2-yl)amino)methyl)phenol, characterized in that the compound has the following structural formula:

[0009]

[0010] The second objective of this invention is to provide a first method (one-step method) for preparing compounds, the method being as follows:

[0011] Dissolve 5-methyl-2-aminopyridine in an organic solvent, add 5-chlorosalicylaldehyde solution dropwise while stirring, react at 50-70℃ for 2-8 h, and cool to room temperature; place in an ice-water bath, add reducing agent while stirring; remove ice-water bath, react at room temperature for 1-3 h, add water dropwise until no bubbles are generated, add saturated sodium hydroxide solution dropwise while stirring, react at room temperature for 15 min; remove organic solvent by rotary evaporation, extract aqueous phase with ethyl acetate or dichloromethane, combine organic phases, add anhydrous magnesium sulfate or anhydrous sodium sulfate and dry for 30 min, filter, rotary evaporate, and recrystallize from ethanol to obtain the compound.

[0012] The technical route of the first method for preparing the multifunctional probe of the present invention is as follows:

[0013]

[0014] A second objective of this invention is to provide a second method (stepwise method) for preparing compounds, the method being as follows:

[0015] Dissolve 5-methyl-2-aminopyridine in an organic solvent, add 5-chlorosalicylic acid solution dropwise while stirring, react at 50-70℃ for 3-8 h, cool to room temperature, allow the solvent to evaporate to obtain a yellow solid, filter, dry, and recrystallize to obtain 5-chlorosalicylic acid acetal 5-methyl-2-aminopyridine Schiff base; dissolve the above Schiff base in an organic solvent, place in an ice-water bath, and add a reducing agent while stirring; when no more bubbles are generated in the reaction solution, remove the ice-water bath, react at room temperature for 1-3 h, add water dropwise until no more bubbles are generated, add saturated sodium hydroxide solution dropwise while stirring, and react at room temperature for 15 min; remove the organic solvent by rotary evaporation, extract the aqueous phase with ethyl acetate or dichloromethane, combine the organic phases, add anhydrous magnesium sulfate or sodium sulfate and dry for 30 min, filter, rotary evaporation, and recrystallize from ethanol to obtain the compound.

[0016] The technical route of the second method for preparing the multifunctional probe of the present invention is as follows:

[0017]

[0018] Furthermore, the organic solvent is one of methanol, ethanol, ethyl acetate, acetonitrile, tetrahydrofuran, dichloromethane, or chloroform, and the reducing agent is one of sodium borohydride, potassium borohydride, sodium acetoxyborohydride, or sodium cyanoborohydride. The reaction temperature is 0–100℃; the molar ratio of the reactants aldehyde to amine is 1:3–3:1; and the reaction time is 0.2–10 h.

[0019] The third objective of this invention is to provide the application of probes in the qualitative identification and quantitative detection of iron ions and silver ions.

[0020] Furthermore, under natural light, the naked eye can simultaneously identify Fe. 3+ Ag + Fe 2+ Under ultraviolet light, Fe can be simultaneously identified with the naked eye. 3+ Ag + Qualitative and quantitative detection of Fe by ultraviolet spectroscopy 3+ Qualitative and quantitative detection of Fe by fluorescence spectroscopy 3+ Ag + .

[0021] Furthermore, it is used for qualitative and quantitative sensing detection of iron and silver ions in samples such as food, pharmaceuticals, health products, crops, seafood, traditional Chinese medicine, various water bodies, industrial wastewater, industrial waste residue, and soil. The sensing detection includes naked-eye qualitative identification under natural light and ultraviolet light, fluorescence qualitative identification and content detection, and ultraviolet qualitative identification of Fe. 3+ And its content detection.

[0022] Furthermore, the fluorescence qualitative identification also includes the ability to identify whether the detection solution contains Zn after the probe is mixed with silver ions.2+ Cr 3+ Al 3+ Mn 2+ Cu 2+ Pb 2+ K + Ca 2+ Na + Metal ions, etc.

[0023] The above technical solution can achieve the following beneficial effects:

[0024] 1. The multifunctional probe compound provided by this invention is a small molecule compound containing only two six-membered ring skeletons. It has a simple structure, readily available raw materials, and is easy to synthesize. It does not require complex procedures such as column chromatography and can be purified by recrystallization alone.

[0025] 2. The multifunctional probe provided by this invention enables simultaneous naked-eye identification of iron ions and silver ions; and enables qualitative and quantitative detection of Fe by ultraviolet light. 3+ 1. Qualitative and quantitative detection of Fe by fluorescence method 3+ Ag + It enables the identification of whether a detection solution contains Zn. 2+ Cr 3+ Al 3+ Mn 2+ Cu 2+ Pb 2+ K + Ca 2+ Na + This probe is effective against metal ions; it has good selectivity, high sensitivity, strong resistance to interference from other metal ions, fast detection speed, and low detection limit.

[0026] Furthermore, significant color changes can be observed under natural light, allowing for immediate identification of Fe through different colors. 3+ Ag + Fe 2+ Compared to other probes that utilize fluorescence or ultraviolet color development, this probe requires no instruments and can identify Fe in real time using only the naked eye. 3+ Ag + Fe 2+ It is more convenient and intuitive, requires no professional personnel, and is less expensive. Furthermore, based on the significant color change specific to this probe, it can be used as a specific indicator for detecting the presence of iron or silver ions in aqueous solutions.

[0027] Given the aforementioned characteristics of the probe, this probe has broad application prospects in the identification and content detection of iron and silver ions in food, pharmaceuticals, health products, crops, seafood, traditional Chinese medicine, various water bodies (including industrial wastewater and waste residue), and soil. Attached Figure Description

[0028] Figure 1 This is a photograph under natural light showing the selective recognition of metal ions by the multifunctional probe of this invention (a: metal ions from left to right: Mn). 2+ Zn 2+ Cd 2+ K + Ca 2+ Na + Ag + a, Fe 3+ Fe 2+ Cu 2+ Co 2+ Mg 2+ Al 3+ Pb 2+ Cr 3+ b: Metal ions from left to right are Fe 2+ Ag + a, Fe 3+ (Where "a" indicates the probe itself, without any added metal ions)

[0029] Figure 2 This is the ultraviolet absorption spectrum of the multifunctional probe of this invention for selective recognition of metal ions.

[0030] Figure 3 This invention provides a multifunctional probe for Fe at different concentrations. 3+ UV absorption spectrum response diagram

[0031] Figure 4 These are ultraviolet light photographs showing the selectivity of the multifunctional probe of this invention for different metal ions (metal ions from left to right: Mn). 2+ Zn 2+ Cd 2+ K + Ca 2+ Na + Ag + a, Fe 3+ Fe 2+ Cu 2+ Co 2+ Mg 2+ Al 3+ Pb 2+ Cr 3+ (Where "a" indicates the probe itself, without any added metal ions)

[0032] Figure 5 This is a fluorescence emission spectrum of the multifunctional probe of the present invention for different metal ions.

[0033] Figure 6This invention provides a multifunctional probe for Fe at different concentrations. 3+ Fluorescence response spectrum

[0034] Figure 7 This invention relates to a multifunctional probe for detecting Fe. 3+ Fluorescence response diagram with interference from other metal ions

[0035] Figure 8 This invention provides a multifunctional probe for different concentrations of Ag. + Fluorescence response spectrum

[0036] Figure 9 This invention relates to a multifunctional probe and Ag. + Fluorescence emission spectrum of selective recognition of other metal ions after mixing Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 1-9 Further explanation of the present invention:

[0038] To better understand the present invention, the following embodiments further illustrate its content; however, the scope of the present invention is not limited to the embodiments described below. Those skilled in the art can make various modifications or alterations to the present invention, and these equivalent forms are also within the scope defined by the claims listed in this application.

[0039] Example 1: Synthesis of probe compounds

[0040] Accurately weigh 0.1081 g (1 mmol) of 5-methyl-2-aminopyridine and 5 mL of methanol, place them in a 100 mL round-bottom flask, and add 7 mL of methanol solution containing 0.1565 g (1 mmol) of 5-chlorosalicylic acid aldehyde dropwise while stirring. React at 70 °C for 6 h. After cooling, pour the reaction solution into a beaker, and the solvent evaporates to obtain a yellow solid. After filtration, drying, and recrystallization from methanol, obtain the 5-chlorosalicylic acid acetal 5-methyl-2-aminopyridine Schiff base.

[0041] Accurately weigh 0.7438 g (3 mmol) of the above-mentioned Schiff base, 25 mL of methanol, and 5 mL of tetrahydrofuran, and add them to a round-bottom flask. After complete dissolution, place the flask in an ice-water bath and, while stirring, add 0.5675 g (15 mmol) of sodium borohydride in small, repeated additions to the reaction flask. After no more bubbles are generated in the reaction solution, remove the ice-water bath and react at room temperature for 1 hour. Add 2 drops of water, and while stirring, add 10 mL of saturated sodium hydroxide solution. React at room temperature for 15 minutes. Remove the organic solvent by vacuum rotary evaporation. Extract the aqueous phase three times with 30 mL of ethyl acetate. Combine the organic phases in a 100 mL Erlenmeyer flask. Add anhydrous magnesium sulfate and dry for 30 minutes. Filter, rotary evaporate, and recrystallize from ethanol to obtain the compound.

[0042] The compound is a white crystalline solid with a yield of 56.8%. Melting point: 171-173℃. 1 H NMR(500MHz,Chloroform-d)δ7.87–7.83(m,1H),7.23(dd,J=8.5,2.3Hz,1H),7.15–7.09(m,2H),6.87 –6.81(m,1H),6.38(dd,J=8.5,0.7Hz,1H),5.01(t,J=6.4Hz,1H),4.35(d,J=6.5Hz,2H),2.15(s,3H). 13 C NMR(126MHz,Chloroform-d)δ155.43,155.24,144.83,139.82,130.64,129.31,128.31,124.02,122.28,119.92,109.99,42.24,17.37.HR-MS(ESI),Calcd C 13 H 13 ClN2O,[M+H] + m / z:249.0795, found:249.0800.

[0043] The structural formula of the obtained multifunctional probe compound is as follows:

[0044]

[0045] Example 2: Application of multifunctional naked-eye recognition, ultraviolet and fluorescent probe compounds

[0046] The multifunctional probe compound prepared in Example 1 was dissolved in DMF (N,N-dimethylformamide) to prepare a 10 mM probe stock solution. Each metal ion was dissolved in deionized water to prepare a 30 mM metal ion stock solution. Each stock solution can be diluted to the required concentration according to testing needs. The blank solution system used in the test was a DMF:H2O:buffer solution with a volume ratio of 8:2:0.1, where the buffer solution was a 10 mM HEPES solution and the solvent was deionized water.

[0047] 50 μL of different metal ion solutions were added to colorless, transparent sample vials containing 30 μL of probe solution and 3 mL of blank solution, respectively. Without any instruments, under natural light, it was observed that the added Fe... 3+ Ag + The solution underwent a noticeable color change, such as... Figure 1 As shown, Fe 3+ The solution is yellow, while Ag + The solution is grayish-pink, making it easy to identify and distinguish Fe with the naked eye. 3+ Ag+ In addition, Fe 2+ The solution is transparent with a slightly yellowish tint, while other metal ion solutions are opaque milky white, thus allowing for visual identification and differentiation of Fe. 2+ .

[0048] After adding the sample as described above, place the sample vial under a UV lamp and irradiate it with a wavelength of 254nm, then take a photograph as shown. Figure 2 As shown in the figure. It can be seen from the figure that Fe 3+ The solution is pale yellow, while Ag + The solution appears pale purple, while other solutions show little difference; therefore, Fe can be identified and distinguished with the naked eye using an ultraviolet lamp. 3+ Ag + .

[0049] Take 30 μL of probe solution and 50 μL of metal ion solution, dilute to 3 mL with blank solution, mix well, and then perform the following tests.

[0050] Figure 3 This is the UV spectrum of the probe solution after adding different metal ions. The graph shows that the probe itself exhibits a narrow, weak absorption peak at 323 nm within the 312–346 nm range; while the addition of Fe... 3+ Subsequently, a broad, strong absorption peak appeared in the 290–450 nm range at 321 nm; when other metal ions were added, only a narrow, weak absorption peak appeared in the 306–360 nm range at 323 nm, and the Fe in the ultraviolet spectrum... 3+ The changes are most obvious, so ultraviolet spectroscopy can be used to identify Fe. 3+ .

[0051] Figure 4 Different concentrations of Fe were added dropwise to the probe solution. 3+ The ultraviolet absorption spectrum response diagram of Fe. 3+ With increasing concentration, the absorbance at 323 nm continuously increases, and the maximum absorption wavelength slowly blue-shifts to 321 nm. Data processing yields: absorbance y and Fe 3+ The linear equation for concentration x is: y = 0.0521x – 0.0867, with a linear correlation coefficient R0. 2 =0.9987, Fe 3+ The concentration detection range is 1.0–50 × 10⁻⁶. -5 M, the detection limit is 9.8983×10 -6 M.

[0052] When the compound was used as a fluorescent probe, the maximum excitation wavelength was measured to be 317 nm and the maximum emission wavelength was 367 nm. The fluorescence was very strong, with a fluorescence value as high as 8100. At the same time, there was a very weak peak at 637 nm, with a fluorescence value of only 62. Figure 5 This is a fluorescence emission spectrum after adding different metal ions to the probe. As shown in the figure, at 367 nm: when Fe is added... 2+ Cu 2+ When Al was added, the fluorescence intensity decreased significantly, and the quenching rate was approximately 50%; 3+ Cr 3+ When Fe is added, the fluorescence intensity decreases more significantly, with a quenching rate of approximately 75%, but the fluorescence intensity remains relatively strong (>1800); 3+ At the initial fluorescence intensity, the quenching rate was approximately 99%, and the fluorescence was almost completely quenched. When other remaining metal ions were added, some degree of fluorescence quenching also occurred, but the fluorescence intensity remained very strong (>6500), with a quenching rate of less than 17%. Analysis shows that although the fluorescence intensity was quenched to varying degrees after the addition of metal ions, the addition of Fe... 3+ The fluorescence intensity (74) is even comparable to that of Cr with a fluorescence intensity quenching rate of approximately 75%. 3+ (1821) Compared to Cr, it is only Cr 3+ The intensity of 4% indicates that the fluorescent probe of this invention is effective against Fe. 3+ It exhibits excellent selectivity. Furthermore, at 636nm: Ag is added. + Subsequently, the fluorescence intensity (1931) showed a significant increase, while the fluorescence intensity of the probe was very weak when other metal ions were added, indicating that this probe is effective against Ag. + It also offers a good selection.

[0053] Figure 6 Different concentrations of Fe were added dropwise to the probe solution. 3+ The fluorescence spectrum response diagram is shown. As can be seen from the diagram, with the increase of Fe... 3 + As the amount of Fe increases, the fluorescence intensity gradually weakens; when Fe... 3+ When the concentration is 3 times that of the probe, the fluorescence quenching rate is approximately 97%; when increased to 7 times that of the probe, the fluorescence quenching rate is 99.6%, almost completely quenched. Data processing yields the relationship between fluorescence intensity γ and Fe. 3+ The linear equation for ion concentration x is: y = -814.4x + 8266.6, with a linear correlation coefficient R. 2 =0.9841, Fe 3+ The concentration detection range is 1–8 × 10⁻⁶. -5 M, detection limit is 1.4602×10 -6 M.

[0054] Figure 7It is a fluorescent probe for Fe in the presence of other metal ions. 3+ A bar chart showing the selective effect of fluorescence intensity on Fe. The figure shows the effect of other metal ions on Fe... 3+ The selectivity of Fe is not affected in any way. 3+ Even when coexisting, significant fluorescence quenching still occurs, and the degree of quenching is similar to that of Fe. 3+ The quenching degree is almost the same. Therefore, the presence of other metal ions is important for the fluorescent probe compound of this invention to recognize Fe. 3+ No interference.

[0055] Figure 8 Different concentrations of Ag were added dropwise to the probe solution. + The fluorescence spectrum response diagram; as can be seen from the figure, with Ag... + As the amount added increases, the fluorescence intensity gradually increases, especially when 15 μl of Ag is added. + When the fluorescence intensity reaches its maximum value, continue adding Ag. + The fluorescence intensity begins to decrease slowly. Data processing yields the relationship between fluorescence intensity γ and Ag. + The linear equation for ion concentration x is: y = 16.83x + 42.542, with a linear correlation coefficient R. 2 =0.9836, Ag + The concentration detection range is 0–1.5 × 10⁻⁶. -4 M, detection limit is 2.0534×10 -7 M.

[0056] Figure 9 Ag is added to the probe solution simultaneously. + The graph shows the fluorescence intensity of the probe itself and other metal ions (except Ag). + (Except for) the addition of the probe, the fluorescence intensity was extremely weak. When Ag was added... + After that, only Fe 3+ The fluorescence intensity is still extremely weak (but it can still identify Fe). 3+ While other metal ions showed enhanced fluorescence, Zn exhibited the opposite effect. 2+ Cr 3+ Al 3+ Mn 2+ Cu 2+ Pb 2+ K + Ca 2+ Na + The fluorescence intensity is higher than that of Ag. + The enhancement was 2.6-4.8 times, indicating that the addition of Ag to the probe of this invention... + Then add the test solution, and react with Ag. +By comparing the fluorescence intensity, it is possible to quickly determine whether the test solution contains the above-mentioned ions.

[0057] The above descriptions are all preferred embodiments of the present invention. For those skilled in the art, any modifications to the present invention in various equivalent forms without departing from the principle of the present invention shall fall within the protection scope of the appended claims.

Claims

1. An application of naked-eye recognition, ultraviolet and fluorescent probes, characterized in that: The chemical name is 4-chloro-2-(((5-methylpyridin-2-yl)amino)methyl)phenol, and the compound has the following structural formula: ； The probe is applied to the identification and detection of Fe3+, Ag+, and Fe2+ in food, pharmaceuticals, health products, crops, seafood, traditional Chinese medicine, industrial wastewater, industrial waste residue, and soil samples. Under natural light, Fe3+, Ag+, and Fe2+ can be identified with the naked eye; under ultraviolet light, Fe3+ and Ag+ can be identified with the naked eye; Fe3+ can be qualitatively and quantitatively detected by ultraviolet spectroscopy; and Fe3+ and Ag+ can be quantitatively detected by fluorescence spectroscopy.

2. The application of a naked-eye recognition, ultraviolet, and fluorescent probe according to claim 1, characterized in that: The probe preparation method is as follows: Dissolve 5-methyl-2-aminopyridine in an organic solvent, add 5-chlorosalicylaldehyde solution dropwise while stirring, react at 50-70℃ for 2-8 h, and cool to room temperature; place in an ice-water bath, add reducing agent while stirring; remove ice-water bath, react at room temperature for 1-3 h, add water dropwise until no bubbles are generated, add saturated sodium hydroxide solution dropwise while stirring, react at room temperature for 15 min; remove organic solvent by rotary evaporation, extract aqueous phase with ethyl acetate or dichloromethane, combine organic phases, add anhydrous magnesium sulfate or anhydrous sodium sulfate and dry for 30 min, filter, rotary evaporate, and recrystallize from ethanol to obtain the compound.

3. The application of a naked-eye recognition, ultraviolet, and fluorescent probe according to claim 1, characterized in that: The probe preparation method is as follows: 5-Methyl-2-aminopyridine was dissolved in an organic solvent, and 5-chlorosalicylic acid solution was added dropwise with stirring. The reaction was carried out at 50-70°C for 3-8 h. After cooling to room temperature, the solvent evaporated to give a yellow solid, which was filtered, dried, and recrystallized to obtain the 5-chlorosalicylic acid acetal 5-methyl-2-aminopyridine Schiff base. The above Schiff base was dissolved in an organic solvent and placed in an ice-water bath. A reducing agent was added while stirring. When no more bubbles were generated in the reaction solution, the ice-water bath was removed, and the reaction was carried out at room temperature for 1-3 h. Water was added dropwise until no more bubbles were generated. Saturated sodium hydroxide solution was added dropwise with stirring, and the reaction was carried out at room temperature for 15 min. The organic solvent was removed by rotary evaporation, and the aqueous phase was extracted with ethyl acetate or dichloromethane. The organic phases were combined, dried with anhydrous magnesium sulfate or sodium sulfate for 30 min, filtered, rotary evaporated, and recrystallized from ethanol to obtain the compound.

4. The application of a naked-eye recognition, ultraviolet, and fluorescent probe according to claim 2 or 3, characterized in that: The organic solvent is one of methanol, ethanol, ethyl acetate, acetonitrile, tetrahydrofuran, dichloromethane, or chloroform; the reducing agent is one of sodium borohydride, potassium borohydride, sodium acetoxyborohydride, or sodium cyanoborohydride; the reaction temperature is 0–100 °C; the molar ratio of the reactants aldehyde to amine is 1:3–3:1; and the reaction time is 0.2–10 h.

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