A fluorescent probe for detecting cyanide ion, and a preparation method and application thereof

Abstract

The application discloses a fluorescent probe for detecting cyanide ions, and a preparation method and application thereof. The fluorescent probe has a chemical name of (E)-2-(pyridine-2(1H)-ylidene)-2-(5-(((E)-2-(quinoline-2-yl)vinyl)pyridine-2-yl)acetonitrile. The preparation method comprises the following steps: dissolving (E)-2-(2-(6-bromopyridine-3-yl)vinyl)quinoline in a solvent, and reacting with 2-(pyridine-2-yl)acetonitrile under the action of a catalyst; and the obtained product is recrystallized with ethyl acetate to obtain the fluorescent probe. The fluorescent probe has the advantages of simple synthesis route, easily obtained raw materials, high sensitivity, strong cyanide ion recognition ability, and fast response speed. Meanwhile, the fluorescent probe also has high selectivity and sensitivity in the detection of aqueous solutions. Furthermore, the probe can detect cyanide ions for multiple times, and has a good application prospect in the detection of cyanide ions.

Description

Technical Field

[0001] This invention relates to the field of fluorescent probes, and in particular to a fluorescent probe for detecting cyanide ions, its preparation method, and its application. Background Technology

[0002] Anions are widely present in nature and organisms, playing important roles in environmental science, chemistry, biology, and other fields. Among the many anions, cyanide ions play a crucial role in synthetic fibers, leather products, metallurgy, and electroplating technology. However, large quantities of cyanide-containing wastewater generated during industrial production, if not effectively treated or accidentally leaked, can severely pollute water bodies and soil, posing a long-term threat to aquatic organisms and ecosystems, and even accumulating through the food chain to affect ecological security. Therefore, developing cyanide ion detection methods with high selectivity, high sensitivity, and low cost is of great practical significance for real-time monitoring of industrial wastewater, environmental risk assessment, and pollution control.

[0003] In recent years, anion fluorescent probes have been widely used due to their good selectivity, high detection sensitivity, strong anti-interference ability, and simple operation. The main principle of anion detection using fluorescent probes is to observe the specific reaction between the anion and the fluorescent probe molecules using fluorescence spectroscopy, which leads to changes in the structure of the fluorescent molecules. This change in fluorescence signal is then used to achieve quantitative and qualitative analysis of the anion. Currently, many anion fluorescent probes with potential applications have been designed and synthesized. However, most probes are complex to synthesize, costly, and lack repeatability, and it is difficult to recognize anions in aqueous solutions. Therefore, developing a class of fluorescent probes with high sensitivity, capable of repeatedly recognizing anions, and able to detect cyanide ions in aqueous solutions is of great significance.

[0004] Quinoline derivatives are excellent fluorophores due to their high absorption intensity in the visible to near-infrared spectral region, high fluorescence quantum yield, relatively long excited singlet state lifetime, and good chemical stability. Therefore, they can be used as potential fluorophores to design anion fluorescent probes. Meanwhile, quinoline dyes are also widely used in research fields such as biological probes, fluorescent switches, and light-harvesting arrays, becoming a major research target for current chemical researchers. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a fluorescent probe for detecting cyanide ions, its preparation method, and its application.

[0006] The objective of this invention can be achieved through the following technical solutions: A fluorescent probe for detecting cyanide ions has the chemical name (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile), and its structural formula is as follows: .

[0007] Accordingly, the present invention also provides a method for preparing the above-mentioned fluorescent probe for detecting cyanide ions, comprising dissolving (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline in a solvent and reacting it with 2-(pyridin-2-yl)acetonitrile in the presence of a catalyst, and recrystallizing the resulting product with ethyl acetate to obtain the fluorescent probe.

[0008] Further, the solvent is tetrahydrofuran, the catalyst is NaH, and the reaction is purged with an inert gas before the reaction. The ratio of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline, 2-(pyridin-2-yl)acetonitrile, and NaH is 0.5g:0.385g:0.26g.

[0009] Further, the preparation method of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline includes: reacting 2-bromo-5-aldehyde pyridine with 2-methylquinoline in a nitrogen atmosphere, and recrystallizing the product with ethanol to obtain (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline.

[0010] Furthermore, the ratio of 2-bromo-5-aldehyde pyridine to 2-methylquinoline is 3.00 g: 3.46 g / L.

[0011] This invention also provides the application of the above-mentioned fluorescent probe for detecting cyanide ions in the detection of cyanide ions in aqueous solutions.

[0012] Furthermore, in applications where ultraviolet absorption and fluorescence emission spectroscopy are used for detection, the fluorescent probe is dissolved in a 9:1 mixture of DMSO and water to test for cyanide ions.

[0013] The fluorescent probe of this invention uses quinoline as the fluorophore and the hydrocarbons in arylacetonitrile as recognition sites. It exhibits a UV absorption peak at 475 nm under the conditions of DMSO and water (V / V = 9:1) as solvents. The addition of CN... - Subsequently, the absorption peak at 465 nm decreased. However, the addition of other anions did not significantly change the UV absorption spectrum of the fluorescent probe. In the fluorescence spectrum, using 465 nm as the excitation wavelength, the maximum emission wavelength of the fluorescent probe was 575 nm, exhibiting strong yellow fluorescence. The addition of CN... - The fluorescence intensity at 575 nm decreased significantly, while the addition of other anions did not cause a significant change in fluorescence intensity.

[0014] Compared with existing technologies, the fluorescent probe of this invention has a simple synthesis route, readily available raw materials, high sensitivity, strong recognition ability for cyanide ions, and fast response speed; at the same time, it also has high selectivity and sensitivity in aqueous solutions; and the probe can detect cyanide ions multiple times, showing great application prospects in the detection of cyanide ions. Attached Figure Description

[0015] Figure 1 The fluorescent probe of this invention (20 μmol•L) -1 Add different anions (20 μmol•L) to a DMSO and water (V / V = 9 / 1) solution. -1 UV absorption spectrum at time ( ); Figure 2 The fluorescent probe of this invention (20 μmol•L) -1 Add different anions (480 μmol•L) to a DMSO and water (V / V = 9 / 1) solution. -1 fluorescence emission spectrum (λ) at time ex =465 nm); Figure 3 The fluorescent probe of this invention (20 μmol•L) -1 DMSO and water (V / V=9 / 1) solutions in different CN - Concentration (0-480 μmol•L) -1 The ultraviolet absorption spectrum below; Figure 4 For A514nm and CN - Concentration relationship curve; Figure 5 The fluorescent probe of this invention (20 μmol•L) -1 DMSO and water (V / V=9 / 1) solutions in different CN - Concentration (0-480 μmol•L) -1 Fluorescence emission spectrum under ( ) Figure 6 For I533nm and CN - Concentration relationship curve; Figure 7-8 The fluorescent probe of this invention (20 μmol•L) -1 ) with other anions (480 μmol•L -1 When coexisting, CN - (480 μmol•L) -1 A bar chart showing the change in I / I0 during the response. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0017] This invention provides a method for preparing a fluorescent probe for detecting cyanide ions. Using pyrrole and benzaldehyde as raw materials, the probe is obtained through condensation, bromination, oxidation, fluorination-boronation, and then nucleophilic substitution reaction with phenylacetonitrile. The reaction process is as follows:

[0018] The specific preparation process steps are as follows: (1) Synthesis of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline: In a nitrogen atmosphere, 2-bromo-5-aldehyde pyridine and 2-methylquinoline were mixed and stirred at 120°C. After the reaction was completed, the mixture was removed and cooled to room temperature. A solid precipitated out. The mixture was filtered, recrystallized from ethanol, and filtered again to give a yellow solid (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline. (2) Synthesis of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile: Add NaH to a three-necked flask to replace the nitrogen gas, then add tetrahydrofuran. After stirring for five minutes, add 2-(pyridin-2-yl)acetonitrile and continue stirring for another thirty minutes. Then dissolve the (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline prepared in step (1) in tetrahydrofuran and add it to the reaction flask. Let it react overnight. After the reaction is complete, pour it into water, and a solid will precipitate. Filter the solution. Recrystallize from ethyl acetate and filter to obtain an orange solid.

[0019] The names, specifications, and manufacturers of the various raw materials used in the embodiments of this invention are shown in Table 1. 2-Bromo-5-aldehyde pyridine 25g Shanghai Titan Technology Co., Ltd. 2-Methylquinoline 25g Shanghai Titan Technology Co., Ltd. Tetrahydrofuran 500mL Shanghai Titan Technology Co., Ltd. Pyridine-2-acetonitrile 25g Shanghai Titan Technology Co., Ltd. ethanol 5L Shanghai Titan Technology Co., Ltd. Ethyl acetate 4L Shanghai Titan Technology Co., Ltd. Sodium hydride 250g Shanghai Titan Technology Co., Ltd. Trifluoroacetic acid 500mL Shanghai Titan Technology Co., Ltd. The silicone column used in the various embodiments of the present invention is a silicone column with a length of 45cm and a diameter of 45mm, manufactured by Beijing Lianhua Glass Instrument Co., Ltd. Example 1

[0020] I. Synthesis of a fluorescent probe for detecting cyanide ions: (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile molecule The fluorescent probe molecule for detecting cyanide ions in this invention is synthesized from 2-bromo-5-aldehyde pyridine and 2-methylquinoline through condensation and nucleophilic substitution reactions.

[0021] (1) Synthesis of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline: 2-Bromo-5-aldehydepyridine (3.00 g, 16.13 mmol) and 2-methylquinoline (3.46 g, 24.19 mmol) were added to a 250 mL round-bottom flask, which was purged with nitrogen. The reaction was stirred at 120°C for 12 h. After the reaction was complete, it was cooled to room temperature, and a solid precipitated. The precipitate was filtered, recrystallized from ethanol, and filtered again to give a pale yellow solid (2.8 g, 65%).

[0022] The pale yellow solid powder product obtained above was measured using a nuclear magnetic resonance instrument (Bruker AVANCE III 500MHz), and the data are shown below: 1 H NMR (500 MHz, DMSO), δ8.70 (d, J =2.5Hz, 1H), 8.169(m,1H), 8.3015(m,1H), 7.97(m,1H), 7.87 (m,2H), 7.78 (m,1H), 7.69(d, J =8Hz, 1H), 7.64(d, J =16.5Hz, 1H), 7.58(m, 1H); Analysis of the nuclear magnetic resonance spectroscopy data of the pale yellow solid powder product obtained above showed that the yellow solid powder product obtained above is (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline.

[0023] (2) Synthesis of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile: In a 100 mL three-necked flask, 0.77 g (32.14 mmol) of NaH was added to replace the nitrogen gas. Then, 20 mL of tetrahydrofuran was added, and the mixture was stirred for five minutes. 2-(pyridin-2-yl)acetonitrile (1.14 g, 9.64 mmol) was added, and the mixture was stirred for another thirty minutes. Then, (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline (1.00 g, 3.21 mmol) prepared in step (1) was dissolved in 15 mL of tetrahydrofuran and added to the reaction flask. The reaction was allowed to proceed overnight. After the reaction was complete, the mixture was poured into water, and a solid precipitated. The solid was filtered. Ethyl acetate was recrystallized, and the precipitate was filtered to obtain an orange solid (0.4 g, 56%).

[0024] The orange solid powder product obtained above was measured using a nuclear magnetic resonance instrument (Bruker AVANCE III 500 MHz), and the data are shown below: 1 H NMR (500 MHz, DMSO), δ 15.81 (s, 1H), 8.44 (s ,1H), 8.32 (d, J = 8.5Hz, 1H), 8.227(s,1H), 8.127 (d, J = 9Hz, 1H), 7.97 (d, J = 8.5Hz, 2H), 7.92(d, J =7.5Hz, 1H), 7.829(m, 3H),7.55(m,1H),7.37(d, J =16.5Hz, 1H), 7.27(d, J =9Hz,2H), 6.84(m,1H); Analysis of the nuclear magnetic resonance spectroscopy data of the orange solid powder product obtained above showed that the orange solid product obtained above is (E)-2-(pyridine-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridine-2-yl)acetonitrile).

[0025] II. Recognition performance of the fluorescent probe for detecting cyanide ions (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile for anions 1. Selectivity study of fluorescent probes for cyanide ions Prepare a 20 μmol•L⁻¹ DMSO solution by dissolving (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile; prepare CN₂ solution separately. - , F - , Cl - , Br - , I - AcO - H2PO4 - HSO4 - ClO4 - BF4 - NO3 - SCN - S2 - ,OH - HSO3 - CO32- HCO3 - 5000 μmol•L -1 DMSO solution, measure 0.4 mL of 5000 μmol•L -1 The probe solution was diluted to 100 mL with a mixture of DMSO and water (V / V = 9 / 1) and divided into 21 groups (5 mL each). The first group served as a blank experiment. 24 equivalents of various anion solutions were added to each of the other groups. The results were obtained by analyzing UV absorption and fluorescence emission spectra (λ). ex =465nm), observe the response of the fluorescent probe (E)-2-(pyridine-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridine-2-yl)acetonitrile to various anions.

[0026] The results showed that (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile, in the presence of DMSO and water (V / V=9:1) as solvents, exhibited absorption peaks at 475 nm and 325 nm, respectively. The addition of CN... - Afterwards, the absorption peaks at 475 nm and 325 nm showed a red shift, while the UV absorption spectrum of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile did not change significantly upon the addition of other anions. Figure 1 In the fluorescence spectrum, with 465 nm as the excitation wavelength, the maximum emission wavelength of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile is 575 nm, exhibiting strong fluorescence. The addition of CN... - Afterwards, the fluorescence intensity at 575 nm decreased significantly, and a new fluorescence appeared at 610 nm. However, the emission wavelength of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile did not change significantly upon the addition of other anions. Figure 2 This indicates that the fluorescent probe can specifically detect cyanide ions.

[0027] 2. Fluorescent probe titration experiment of cyanide ions (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile was dissolved in DMSO to prepare a solution of 5000 μmol•L -1 The stock solution was prepared in DMSO to form CN. - Stock solution, concentration 50000 μmol•L-1 Measure 100 μL of 5000 μmol•L -1 The probe was dissolved in a 5 mL volumetric flask, and 0.5 mL of water was added. The solution was then diluted to 5 mL with DMSO solution to prepare a 5 mL probe solution in a 20 μM DMSO and water (V / V = 9:1) mixture. Titration experiment: 5 mL of the 20 μM DMSO and water (V / V = 9:1) mixture was poured into a 10 mL wide-mouth conical flask. 0.2 μL of 50000 μmol·L⁻¹ was added dropwise each time. -1 (2.0 equivalent) CN - After shaking the solution thoroughly, measure its ultraviolet absorption spectrum and fluorescence emission spectrum. Repeat this operation until 24.0 equivalents of cyanide ion solution are added.

[0028] The results showed that the UV absorption spectrum of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile was affected by the concentration of cyanide ions. Figure 3-4 With the gradual addition of cyanide ions, the absorption peaks of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile at 475 nm and 325 nm gradually decreased until 480 μmol•L was added. -1 CN - Equilibrium was reached at that time. Then, its fluorescence emission spectrum was measured. Figure 5-6 The fluorescence intensity of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile was very strong at 575 nm. With the addition of cyanide ions, the fluorescence intensity gradually decreased and a slight red shift occurred until 480 μmol•L was added. -1 CN - A balance is reached at that time.

[0029] 3. Anti-interference capability test Pour 5 mL of the probe solution, a mixture of 20 μM DMSO and water (V / V = 9:1), into 21 15 mL test tubes, 5 mL in each tube. The first tube serves as a blank control. Add 48 μL of 50000 μmol•L to each of the remaining tubes. -1 Different anions (CN) - , F - , Cl - , Br - , I - AcO - H2PO4 - HSO4 -ClO4 - BF4 - NO3 - SCN - S2 - ,OH - HSO3 - CO3 2- HCO3 - (Wait a moment) Shake thoroughly, perform ultraviolet absorption spectroscopy and fluorescence emission spectroscopy detection, and finally add 48 μL of 50000 μmol•L to each test tube. -1 The cyanide ions were removed, shaken well, and their ultraviolet absorption and fluorescence emission spectra were detected again.

[0030] Experiments show that, when coexisting with other anions, CN... - It can still reduce the UV absorption peak of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinoline-2-yl)vinyl)pyridin-2-yl)acetonitrile at 475 nm, and can significantly reduce the fluorescence intensity of (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinoline-2-yl)vinyl)pyridin-2-yl)acetonitrile at 575 nm. Figure 7-8 Therefore, (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile against CN - The detection system has excellent anti-interference capabilities, and other anions will not interfere with the detection results.

[0031] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A fluorescent probe for detecting cyanide ions, characterized in that, Its chemical name is (E)-2-(pyridin-2(1H)-ylidene)-2-(5-(((E)-2-(quinolin-2-yl)vinyl)pyridin-2-yl)acetonitrile), and its structural formula is as follows: 。 2. A method for preparing a fluorescent probe for detecting cyanide ions as described in claim 1, characterized in that, (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline was dissolved in a solvent and reacted with 2-(pyridin-2-yl)acetonitrile in the presence of a catalyst. The resulting product was recrystallized from ethyl acetate to obtain the fluorescent probe.

3. The preparation method according to claim 2, characterized in that, The solvent is tetrahydrofuran, the catalyst is NaH, and the reaction is purged with an inert gas before the reaction. The ratio of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline, 2-(pyridin-2-yl)acetonitrile, and NaH is 0.5g:0.385g:0.26g.

4. The preparation method according to claim 2, characterized in that, The preparation method of (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline includes reacting 2-bromo-5-aldehyde pyridine with 2-methylquinoline in a nitrogen atmosphere, and recrystallizing the product with ethanol to obtain (E)-2-(2-(6-bromopyridin-3-yl)vinyl)quinoline.

5. The preparation method according to claim 4, characterized in that, The ratio of 2-bromo-5-aldehyde pyridine to 2-methylquinoline is 3.00 g: 3.46 g.

6. The use of the fluorescent probe according to any one of claims 1-5 in the detection of cyanide ions in aqueous solutions for non-diagnostic or therapeutic purposes.

7. The application of the fluorescent probe for detecting cyanide ions according to claim 6, characterized in that, When using ultraviolet absorption and fluorescence emission spectroscopy for detection, the fluorescent probe is dissolved in a 9:1 mixture of DMSO and water to test for cyanide ions.

Images