Naked eye recognition, ultraviolet and fluorescent probe, preparation method and application thereof

Abstract

The invention discloses a naked eye recognition, ultraviolet and fluorescent probe as well as a preparation method and application thereof. The probe is obtained by taking 5-methyl-2-aminopyridine and 5-chlorosalicylaldehyde as raw materials, reacting for a period of time, adding a reducing agent and purifying. According to the invention, Fe < 3 + >, Fe < 2 + > and Ag < + > can be simultaneously identified by naked eyes under natural light, and Fe < 3 + > and Ag < + > can also be identified by naked eyes under an ultraviolet lamp; the content of Fe < 3 + > can be identified and detected through an ultraviolet spectrum, and the content of Fe < 3 + > and Ag < + > can be identified and detected through a fluorescence spectrum. The probe is a small molecule compound, is simple to synthesize, has the advantages of good selectivity, high sensitivity, fast response, low detection limit, real-time detection and the like, and has potential application in recognition and content detection of iron ions and silver ions in drugs, various water areas, soil and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of probes, and particularly relates to a naked-eye recognition, ultraviolet and fluorescence probe, a preparation method thereof, and an application thereof. Background Art

[0002] Iron and silver are important metal elements and have wide applications in the fields of pharmaceuticals, electroplating, water treatment, imaging, electrical and electronics, etc. Iron ions are one of the most important metal elements in organisms and exist in organisms in various forms such as hemoglobin, iron-containing enzymes, ferritin, hemosiderin, etc.; silver has excellent physical, chemical, and broad-spectrum antibacterial properties and occupies an important position in industry and commerce. Ag pollution in the ecological environment mainly comes from industrial wastewater and waste residues. Deficiency or excess of Fe + 、Fe 3+ 、Fe 2+ or Fe 3+ 、Fe 2+ 、Ag + will cause serious harm to humans, animals, plants, and the ecological environment, etc. Therefore, rapid recognition and accurate detection of the content of Fe 3+ 、Fe 2+ 、Ag + have important significance.

[0003] At present, common methods for detecting metal ions include atomic absorption method, electrochemical method, atomic fluorescence method, inductively coupled plasma mass spectrometry and other analytical methods. However, the common defects of these methods are that sample processing is cumbersome, time-consuming, and the instruments are expensive, which makes them have great limitations in practical applications. Especially for most small and medium-sized enterprises, they cannot implement detection in real time and conveniently.

[0004] The ultraviolet method and the fluorescence method are widely used due to their advantages such as cheap instruments, simple operation, strong selectivity, high sensitivity, and fast speed; in addition, realizing naked-eye qualitative recognition of metal ions through color change (under ultraviolet light or natural light), especially naked-eye recognition under natural light without any instrument equipment, is the most convenient, cheap, intuitive, time-saving, real-time, and on-site method for detecting metal ions.

[0005] At present, many ultraviolet probes and fluorescence probes that can respectively recognize Fe 3+ 、Ag + 、Fe 2 have been developed. However, developing small molecule probes with high selectivity, high sensitivity, fast multi-functionality, and easy synthesis that can simultaneously recognize Fe 3+ 、Ag + 、Fe 2 by naked eyes, or simultaneously qualitatively and quantitatively detecting Fe 3+ 、Ag + by fluorescence is still a difficult problem. Summary of the Invention

[0006] The object of the present invention is to design a naked-eye recognition, ultraviolet and fluorescence probe, a preparation method thereof and an application, which can simultaneously recognize Fe 3+ , Ag + , Fe 2 .

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The first object of the present invention is to provide a naked-eye recognition, ultraviolet and fluorescence probe. The chemical name of the compound is 4-chloro-2-(((5-methylpyridin-2-yl)amino)methyl)phenol, and its characteristics are as follows: The compound has the following structural formula:

[0009]

[0010] The second object of the present invention is to provide a first method (one-step method) for preparing the compound. The method is as follows:

[0011] Dissolve 5-methyl-2-aminopyridine in an organic solvent, dropwise add a 5-chlorosalicylaldehyde solution under stirring, react at 50-70 °C for 2-8 h, and cool to room temperature; place it in an ice-water bath, add a reducing agent while stirring; remove the ice-water bath, react at room temperature for 1-3 h, dropwise add water until no bubbles are generated, dropwise add a saturated sodium hydroxide solution while stirring, and react at room temperature for 15 min; rotary evaporate to remove the organic solvent, extract the aqueous phase with ethyl acetate or dichloromethane, combine the organic phases, add anhydrous magnesium sulfate or anhydrous sodium sulfate to dry for 30 min, filter, rotary evaporate, and recrystallize with 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] The second object of the present invention is to provide a second method (stepwise method) for preparing the compound. The method is as follows:

[0015] Dissolve 5-methyl-2-aminopyridine in an organic solvent, and dropwise add a solution of 5-chlorosalicylaldehyde with stirring. React at 50 - 70 °C for 3 - 8 h, cool to room temperature, and volatilize the solvent to obtain a yellow solid. After filtration, drying, and recrystallization, 5-chlorosalicylaldehyde 5-methyl-2-aminopyridine Schiff base is obtained; dissolve the above Schiff base in an organic solvent, place it in an ice-water bath, and add a reducing agent while stirring; when no bubbles are generated in the reaction solution, remove the ice-water bath and react at room temperature for 1 - 3 h, add water dropwise until no bubbles are generated, and dropwise add a saturated sodium hydroxide solution 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 evaporate, and recrystallize with 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, the reducing agent is one of sodium borohydride, potassium borohydride, sodium acetoxyborohydride, or sodium cyanoborohydride, and the reaction temperature is 0 - 100 °C; the molar ratio of the reaction raw materials aldehyde to amine is 1:3 - 3:1; the reaction time is 0.2 - 10 h.

[0019] The third object of the present invention is to provide the application of the probe in qualitatively identifying and quantitatively detecting iron ions and silver ions.

[0020] Furthermore, under natural light, visually identify Fe 3+ , Ag + , Fe 2+ simultaneously with the naked eye; under ultraviolet light, visually identify Fe 3+ , Ag + simultaneously with the naked eye; qualitatively and quantitatively detect Fe 3+ by ultraviolet spectroscopy; qualitatively and quantitatively detect Fe 3+ , Ag + by fluorescence spectroscopy.

[0021] Furthermore, it is used for qualitative and quantitative sensing detection of iron ions and silver ions in samples such as food, medicine, health products, crops, seafood, Chinese herbal medicines, various water areas, as well as industrial wastewater, industrial waste residues, and soil. The said 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 said fluorescence qualitative identification also includes that after the probe is mixed with silver ions, it can identify whether Zn is contained in the detection solution2+ , Cr 3+ , Al 3+ , Mn 2+ , Cu 2+ , Pb 2+ , K + , Ca 2+ , Na + and other metal ions.

[0023] The following beneficial effects can be obtained through the above technical solutions:

[0024] 1. The multifunctional probe compound provided by the present invention is a small molecule compound containing only 2 six-membered ring skeletons, with a simple structure, easily available raw materials, and easy to synthesize; no complex procedures such as column chromatography are required, and it can be purified only by recrystallization.

[0025] 2. The multifunctional probe provided by the present invention realizes the simultaneous naked-eye recognition of iron ions and silver ions; it realizes the qualitative and quantitative detection of Fe by ultraviolet method 3+ , the qualitative and quantitative detection of Fe by fluorescence method 3+ , Ag + ; it realizes the recognition of whether the detection solution contains Zn 2+ , Cr 3+ , Al 3+ , Mn 2+ , Cu 2+ , Pb 2+ , K + , Ca 2+ , Na + and other metal ions; the probe has good selectivity, high sensitivity, strong anti-interference ability to other metal ions, fast detection speed, and low detection limit.

[0026] In addition, significant color changes can be observed under natural light, and Fe can be immediately identified by different colors 3+ , Ag + , Fe 2+ . Compared with other probes using fluorescence and ultraviolet color development, this probe does not require any instruments and can simultaneously identify Fe in real time only by the naked eye 3+ , Ag + , Fe 2+ , which is more convenient, more intuitive, does not require professionals, and has lower costs. At the same time, based on the specific significant color changes of this probe, this probe can be used as a specific indicator for detecting the presence of iron ions or silver ions in aqueous solutions.

[0027] In view of the above characteristics of the probe, this probe has broad application prospects in the recognition and content detection of iron ions and silver ions in food, medicine, health products, crops, seafood, Chinese herbal medicines, various water areas (including industrial wastewater and waste residues), soil, etc. Description of the Drawings

[0028] Figure 1 These are the natural light photos of the selective recognition of metal ions by the multifunctional probe of the present invention (a: The metal ions from left to right are: 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: The metal ions from left to right are Fe 2+ , Ag + , a, Fe 3+ ; where "a" represents the probe itself without adding any metal ions)

[0029] Figure 2 These are the ultraviolet absorption spectrograms of the selective recognition of metal ions by the multifunctional probe of the present invention

[0030] Figure 3 These are the ultraviolet absorption spectral response diagrams of the multifunctional probe of the present invention to different concentrations of Fe 3+

[0031] Figure 4 These are the photos under ultraviolet light of the selectivity of the multifunctional probe of the present invention to different metal ions (the metal ions from left to right are: 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" represents the probe itself without adding any metal ions)

[0032] Figure 5 These are the fluorescence emission spectrograms of the selectivity of the multifunctional probe of the present invention to different metal ions

[0033] Figure 6 ​is the fluorescence spectral response diagram of the multifunctional probe of the present invention to different concentrations of Fe 3+

[0034] Figure 7 is the fluorescence response diagram of the interference of other metal ions when the multifunctional probe of the present invention detects Fe 3+

[0035] Figure 8 is the fluorescence spectral response diagram of the multifunctional probe of the present invention to different concentrations of Ag +

[0036] Figure 9 is the fluorescence emission spectral diagram of the selective recognition of other metal ions after the multifunctional probe of the present invention is mixed with Ag + Specific embodiments

[0037] The following combines the appended Figures 1-9 to further illustrate the present invention:

[0038] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments. However, the content of the present invention is not limited to the following embodiments. Those skilled in the art can make various changes or modifications 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 compound

[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 dropwise add 7 mL of a methanol solution containing 0.1565 g (1 mmol) of 5-chlorosalicylaldehyde under stirring. React at 70 °C for 6 h. After cooling, pour the reaction solution into a beaker, and let the solvent evaporate to obtain a yellow solid. After filtration, drying, and recrystallization with methanol, 5-chlorosalicylaldehyde-5-methyl-2-aminopyridine Schiff base is obtained.

[0041] Then accurately weigh 0.7438 g (3 mmol) of the above Schiff base, 25 mL of methanol, and 5 mL of tetrahydrofuran, add them to the round-bottom flask, and wait until completely dissolved. Place the flask in an ice-water bath, and add 0.5675 g (15 mmol) of sodium borohydride in small portions under stirring. After no bubbles are generated in the reaction solution, remove the ice-water bath and react at room temperature for 1 h. Add 2 drops of water, and dropwise add 10 mL of saturated sodium hydroxide solution under stirring, and react at room temperature for 15 min. Remove the organic solvent by vacuum rotary evaporation, extract the aqueous phase 3 times with 30 mL of ethyl acetate, and combine the organic phases in a 100 mL conical flask. Add anhydrous magnesium sulfate to dry for 30 min, filter, rotary evaporate, and recrystallize with ethanol to obtain the compound.

[0042] ​​​​The compound is a white crystal with a yield of 56.8%. The melting point is 171 - 173 °C. 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 ClN 2 O,[M+H] + m / z:249.0795,found:249.0800.

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

[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 probe stock solution with a concentration of 10 mM. Each metal ion was dissolved in deionized water to prepare a metal ion stock solution with a concentration of 30 mM. Each stock solution can be diluted to the required concentration according to the test needs. The blank solution system used in the test is DMF:H 2 O: buffer with a volume ratio of 8:2:0.1, where the buffer is a 10 mM HEPES solution and the solvent is deionized water.

[0047] 50 μL of different metal ion solutions were respectively added to a colorless and transparent sample bottle containing 30 μL of the probe solution and 3 mL of the blank solution. Without any instrument, under natural light, it was found that the solutions containing Fe 3+ 、Ag + showed obvious color changes, as Figure 1 shown, the Fe 3+ solution presented yellow, while the Ag +The solution is gray-pink and can be easily identified and distinguished by naked eyes. 3+ 、Ag + In addition, Fe 2+ The solution is transparent and slightly yellowish, while other metal ion solutions are opaque milky white, so Fe can also be identified and distinguished by naked eyes. 2+ .

[0048] After adding the sample as described above, place the sample bottle under a UV lamp, irradiate with a wavelength of 254 nm, and take a photo. Figure 2 As shown in the figure, Fe 3+ The solution is light yellow, and Ag + The solution is lavender, while other solutions are basically the same, so the naked eye can identify and distinguish Fe with the help of ultraviolet light. 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 perform the following tests.

[0050] Figure 3 It is the UV spectrum after adding different metal ions to the probe solution. As can be seen from the figure, the probe itself has a narrow weak absorption peak at 323nm in the range of 312-346nm; 3+ After addition, a broad and strong absorption peak appeared at 321nm in the range of 290–450nm; when other metal ions were added, only a narrow and weak absorption peak appeared at 323nm in the range of 306–360nm. 3+ The change in Fe is the most obvious, so ultraviolet spectroscopy can be used to identify Fe 3+ .

[0051] Figure 4 Different concentrations of Fe 3+ Ultraviolet absorption spectrum response diagram. As Fe 3+ As the concentration increases, the absorbance at 323nm continues to increase, and the maximum absorption wavelength slowly blue-shifts to 321nm. Data processing shows: absorbance y and Fe 3+ The linear equation of concentration x is: y = 0.0521x–0.0867, and the linear correlation coefficient R 2 =0.9987,Fe 3+ The concentration detection range is 1.0–50×10 -5 M, the detection limit is 9.8983×10 -6 M.

[0052] When the compound is used as a fluorescent probe, the maximum excitation wavelength is measured to be 317 nm, the maximum emission wavelength is 367 nm, the fluorescence is very strong, and the fluorescence value is as high as 8100. At the same time, there is a very weak peak at 637 nm, and the fluorescence value is only 62. Figure 5 It is the fluorescence emission spectrogram after adding different metal ions to the probe. As can be seen from the figure, at 367 nm: when adding Fe 2+ , Cu 2+ , the fluorescence intensity is significantly weakened, and the quenching rate is about 50%; when adding Al 3+ , Cr 3+ , the fluorescence intensity is weakened more significantly, and the quenching rate is about 75%, but the fluorescence intensity is still relatively strong (>1800); when adding Fe 3+ , the quenching rate is about 99%, and the fluorescence is almost completely quenched; when adding the remaining other metal ions, a certain degree of fluorescence quenching also occurs, but the fluorescence intensity is very strong (>6500), and the quenching rate is less than 17%. It can be analyzed that although the fluorescence intensity shows different degrees of quenching after adding metal ions, the fluorescence intensity of adding Fe 3+ (74), even when compared with Cr 3+ with a fluorescence intensity quenching rate of about 75% (1821), is only 4% of the intensity of Cr 3+ , indicating that the fluorescent probe of the present invention has good selectivity for Fe 3+ . In addition, at 636 nm: after adding Ag + , the fluorescence intensity (1931) is significantly enhanced, while when adding other metal ions, the fluorescence intensity of the probe is very weak, indicating that the probe also has good selectivity for Ag + .

[0053] Figure 6 It is the fluorescence spectral response diagram of adding different concentrations of Fe 3+ to the probe solution. As can be seen from the figure, as the addition amount of Fe 3 + increases, the fluorescence intensity gradually weakens; when the concentration of Fe 3+ is 3 times that of the probe, the fluorescence quenching rate is about 97%; when it increases to 7 times that of the probe, the fluorescence quenching rate is 99.6%, almost completely quenched. Through data processing, the linear equation of the fluorescence intensity y and the Fe 3+ ion concentration x is: y = -814.4x + 8266.6, and the linear correlation coefficient R 2 = 0.9841. The detection range of the Fe 3+ concentration is 1–8×10 -5 M, and the detection limit is 1.4602×10 -6 M.

[0054] Figure 7is the bar chart of fluorescence intensity of the fluorescence probe in the presence of other metal ions for Fe 3+ Selectivity influence. It can be seen from the figure that other metal ions have no influence on the selectivity of Fe 3+ . When they coexist with Fe 3+ , obvious fluorescence quenching still occurs, and the quenching degree is almost the same as that of Fe 3+ . Therefore, the presence of other metal ions has no interference on the recognition of Fe 3+ by the fluorescence probe compound of the present invention.

[0055] Figure 8 is the fluorescence spectral response diagram of adding different concentrations of Ag + to the probe solution; it can be seen from the figure that as the addition amount of Ag + increases, the fluorescence intensity gradually increases. When 15 μl of Ag + is added, the fluorescence intensity reaches the maximum value. Continuing to add Ag + , the fluorescence intensity begins to slowly decrease. Data processing gives the linear equation of fluorescence intensity y and Ag + ion concentration x as: y = 16.83x + 42.542, and the linear correlation coefficient R 2 = 0.9836. The detection range of Ag + concentration is 0–1.5×10 -4 M, and the detection limit is 2.0534×10 -7 M.

[0056] Figure 9 is the bar chart of fluorescence intensity when Ag + and other metal ions are added to the probe solution at the same time. It can be seen from the figure that the fluorescence intensity of the probe itself and other metal ions (except Ag + ) is extremely weak after being added to the probe. After adding Ag + , only the fluorescence intensity of Fe 3+ remains extremely weak (Fe 3+ can also be recognized), while other metal ions show enhanced fluorescence, especially Zn 2+ , Cr 3+ , Al 3+ , Mn 2+ , Cu 2+ , Pb 2+ , K + , Ca 2+ , Na + . The fluorescence intensity is enhanced by 2.6 - 4.8 times compared with that of Ag + . It shows that adding Ag + to the probe of the present invention and then adding the test solution, by comparing with Ag +By comparing the fluorescence intensities, it is possible to quickly determine whether the above-mentioned ions are contained in the test solution.

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

Claims

1. A naked eye recognition, ultraviolet and fluorescent probe, chemically named 4-chloro-2-(((5-methylpyridin-2-yl)amino)methyl)phenol, characterized in that: The compound has the following structural formula: 。 2. A method for preparing the probe according to claim 1, characterized in that: The method is as follows: Dissolve 5-methyl-2-aminopyridine in an organic solvent, add 5-chlorosalicylaldehyde solution dropwise while stirring, react at 50-70°C for 2-8 hours, and cool to room temperature; place in an ice-water bath, add a reducing agent while stirring; remove the ice-water bath, react at room temperature for 1-3 hours, add water dropwise until no bubbles are generated, add saturated sodium hydroxide solution dropwise while stirring, and react at room temperature for 15 minutes; 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 anhydrous sodium sulfate, dry for 30 minutes, filter, rotary evaporate, and recrystallize from ethanol to obtain the compound.

3. A method for preparing the probe according to claim 1, characterized in that: The method is as follows: Dissolve 5-methyl-2-aminopyridine in an organic solvent, add 5-chlorosalicylaldehyde solution dropwise under stirring, react at 50-70°C for 3-8 h, cool to room temperature, evaporate the solvent to obtain a yellow solid, filter, dry, and recrystallize to obtain 5-chlorosalicylaldehyde condensed 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 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 bubbles are generated, add saturated sodium hydroxide solution dropwise under 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 to dry for 30 min, filter, rotary evaporate, and recrystallize from ethanol to obtain the compound.

4. A method for preparing naked eye recognition, ultraviolet and fluorescent probes 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 reaction raw materials aldehyde to amine is 1:3-3:1; and the reaction time is 0.2-10 h.

5. Use of the probe according to claim 1 in qualitative identification and quantitative detection of iron ions and silver ions.

6. The use according to claim 5, characterized in that: Under natural light, the naked eye can identify Fe 3+ 、Ag + , Fe 2+ ;Under UV light, identify Fe with naked eyes 3+ 、Ag + ; Qualitative and quantitative detection of Fe by ultraviolet spectroscopy 3+ ; Qualitative and quantitative detection of Fe by fluorescence spectroscopy 3+ 、Ag + .

7. The use according to claim 5, characterized in that: The probe detects Fe in food, medicine, health products, crops, seafood, Chinese herbal medicine, various water bodies, industrial wastewater, industrial waste residue, and soil samples. 3+ 、Ag + , Fe 2 Identification and detection applications.

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