A quinolinyl imidazole Pb 2+ Preparation method and application of fluorescent probe

Abstract

This invention discloses a water-soluble aggregation-induced emission quinolinyl imidazolium Pb 2+ A fluorescent probe is synthesized from 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) via a Duff reaction to generate 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II), which is then reacted with 1,2-dimethylquinoline iodide via a Knoevenagel condensation reaction catalyzed by piperidine. Its chemical structural formula is shown in formula (III). The fluorescent probe of this invention exhibits Pb oxidase activity in aqueous solution. 2+ It has specific identification capabilities, high sensitivity, and strong anti-interference ability, with a detection limit as low as 0.28 μM; this invention provides a simple and rapid method for detecting Pb. 2+ Fluorescent probes have broad application prospects in the environmental and biological fields.

Description

Technical Field

[0001] This invention belongs to the technical fields of organic compound synthesis, fluorescent probes, and fine chemicals, specifically relating to a quinolinyl imidazolium Pb 2+ Fluorescent probe. Background Technology

[0002] Currently, given the serious impacts of harmful metal ions on living systems and the environment, researchers are actively developing fluorescent chemical sensors to detect these ions, with lead poisoning being one of the main concerns. (Pb) 2+ Due to its widespread use in pigments, jewelry, gasoline, and batteries, Pb has become a major source of environmental pollution. Long-term or excessive exposure to Pb can lead to environmental pollution. 2+ Lead can cause a range of serious health problems, including nerve damage, anemia, developmental disorders, memory loss, muscle paralysis, neurological dysfunction, and kidney dysfunction. In particular, it can lead to a decline in IQ, indicating that lead can have harmful effects on multiple targets in the body. Even low doses of lead can have adverse effects on children. 2+ It also exhibits a particularly significant impact. Despite global efforts to reduce lead emissions, lead poisoning remains one of the key challenges urgently needing to be addressed in the field of environmental health. Therefore, the development of Pb... 2+ Probes not only help to gain a deeper understanding of Pb 2+ The study also explored the basic cellular mechanisms of ions in vitro and in vivo, and demonstrated their effective determination in lead-contaminated areas.

[0003] In recent years, various analytical techniques, such as atomic absorption spectrometry (AAS), X-ray fluorescence spectrometry (XRF), capillary electrophoresis (CE), atomic emission spectrometry (AES), inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS), have been applied to Pb. 2+ While current methods for detecting Pb are available, their detection limits and operating ranges are often constrained by sample characteristics, preparation methods, instruments used, and operating conditions. Furthermore, they are typically time-consuming, costly, and require laboratory environments, making them unsuitable for on-site analysis. In contrast, fluorescent probes offer advantages such as high sensitivity, good selectivity, ease of operation, low cost, and real-time monitoring, and are gaining increasing attention. Therefore, developing efficient fluorescent probes with good selectivity and sensitivity for Pb detection is crucial. 2+ It has significant practical implications.

[0004] Based on the above considerations, this invention prepares a novel quinolinyl imidazolium fluorescent probe, which is effective against Pb. 2+ It has specific recognition properties, and its synthesis is simple and yield is high; it is similar to Pb. 2+The fluorescence intensity was significantly enhanced after treatment, and the detection limit was low. Due to its advantages such as fast response, high selectivity and sensitivity, and minimal interference from other metal cations, this probe has great application potential. Summary of the Invention

[0005] For existing Pb detection 2+ To address the shortcomings of the existing methods, this invention utilizes molecular design to prepare a quinolinyl imidazole Pb derivative with good selectivity, high sensitivity, strong anti-interference ability, and low detection limit. 2+ Fluorescent probe.

[0006] The present invention also provides a method for preparing the above-mentioned quinolinyl imidazole fluorescent probe.

[0007] This invention also provides the application of the above-mentioned quinolinyl imidazole fluorescent probes in the field of detection.

[0008] Technical solution: To achieve the above-mentioned objectives, the technical solution of this invention is: a quinolinyl imidazole Pb 2+ The fluorescent probe has the chemical structure shown in formula (III).

[0009]

[0010] The above-mentioned quinolinyl imidazole Pb 2+ A method for synthesizing a fluorescent probe, characterized in that it is synthesized according to the following experimental steps;

[0011] 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) was reacted with Duff to generate 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II), which was then reacted with 1,2-dimethylquinoline iodide in the presence of piperidine via Knoevenagel condensation to give compound (III);

[0012] The above-mentioned quinolinyl imidazole Pb 2+ The specific synthesis reaction formula for the fluorescent probe is as follows:

[0013]

[0014] The steps are completed using the following method:

[0015] 1) Under light-protected conditions, 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) and hexamethylenetetramine were dissolved in trifluoroacetic acid and reacted at 90°C for 2 h to obtain compound (II);

[0016] 2) 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II) was dissolved in methanol with 1,2-dimethylquinoline iodide and piperidine, and reacted at 70°C for 2 h to obtain compound (III).

[0017] The quinolinyl imidazole fluorescent probe of the present invention is effective against Pb in solution. 2+ It exhibits a significant fluorescence response signal.

[0018] Prepare an aqueous solution of the fluorescent probe (III), and add quantitative analytes that may compete with it, including Ca. 2+ Na + 、La 3+ Mn 2+ 、Ba 2+ Ag + Cu 2+ 、Zn 2+ Cd 2+ Hg 2+ Fe 3+ Fe 2+ Al 3+ Co 2+ Ni 2+ K + Mg 2+ Pb 2+ The selective recognition of different metal cations was studied by testing their fluorescence emission spectra, and the results are as follows: Figure 1 As shown, the fluorescence emission intensity change revealed that the fluorescent probe (III) of this invention is effective against Pb. 2+ It exhibits strong fluorescence responsiveness; when this fluorescent probe reacts with Pb... 2+ The fluorescence intensity increased significantly after treatment, while other metal ions did not cause significant changes in fluorescence intensity under the same conditions, indicating that this probe is effective against Pb. 2+ It exhibits high specificity and selectivity. Additionally, a certain amount of probe solution was taken, and Pb was gradually added... 2+ Up to 22 μM; the fluorescence intensity of fluorescent probe (III) gradually increased at 620 nm and at Pb 2+ The fluorescence intensity reaches its maximum at 20 μM. Further increasing the lead ion content results in almost no change in fluorescence intensity, indicating that lead ion saturation has been reached. The results are as follows: Figure 2 As shown. Fluorescent probe (III) is added with Pb 2+ During the process, the maximum fluorescence emission intensity at 620 nm was selected as the ordinate, Pb 2+ Using concentration as the x-axis, a linear regression equation was obtained through linear fitting: y = 35.63194x + 62.5016. The results are as follows... Figure 3As shown, therefore, this fluorescent probe can be used for Pb in this range. 2+ Quantitative analysis and detection.

[0019] The quinolinyl imidazole Pb of the present invention 2+ Fluorescent probes for detecting Pb 2+ It exhibits superior robustness against various potential competing analytes, as shown in the following results. Figure 4 As shown, the fluorescence intensity of the fluorescent probe (III) hardly changed upon the addition of other analytes, thus confirming that the fluorescent probe (III) described in this invention is effective against Pb in aqueous solution. 2+ It has unique fluorescence selectivity and strong anti-interference ability.

[0020] The quinolinyl imidazole Pb of the present invention 2+ Fluorescent probes are characterized by short response times, such as Figure 5 As shown, in Pb 2+ In the presence of Pb, the fluorescence emission intensity essentially saturates after 20 seconds. This fast-response probe can be used for Pb. 2+ The real-time detection indicates that the probe has high sensitivity.

[0021] The quinolinyl imidazole Pb of the present invention 2+ The fluorescent probe exhibits good performance at pH values ​​between 3 and 7. The probe demonstrates strong and stable fluorescence emission for the recognition of lead ions, and its wide pH range helps improve the actual detection performance of the fluorescent probe.

[0022] The beneficial effects of the present invention are as follows: (1) The synthesis method of the fluorescent probe is simple, the reaction conditions are mild, and the purification and separation methods are convenient; (2) The probe has good water solubility and can be used for cell and organism fluorescence imaging; (3) The fluorescent probe has good selectivity, strong anti-interference ability, high sensitivity, and detection limit as low as 0.28 μM, and has broad application prospects in analytical chemistry, environmental detection, food detection, and biological fluorescence imaging. Attached Figure Description

[0023] Figure 1 The concentration of fluorescent probe (III) is 1×10 -5 Fluorescence emission intensity diagrams after adding 5 equivalents of different metal ions to a mol / L aqueous solution.

[0024] Figure 2 The concentration of fluorescent probe (III) is 1×10 -5 Pb was carried out in an aqueous solution of mol / L 2+ Fluorescence emission intensity titration plot, with fluorescence emission intensity on the ordinate and emission wavelength on the abscissa, and excitation wavelength λ. ex =440nm.

[0025] Figure 3 It is a fluorescent probe (III) to select different concentrations of Pb 2+ This is a linear fit plot with the x-axis and the y-axis as the maximum fluorescence emission intensity at the maximum fluorescence emission wavelength of 620 nm; the x-axis represents the value of Pb added. 2+ The concentration, in units of 10 -5 mol / L.

[0026] Figure 4 The concentration of fluorescent probe (III) is 1×10 -5 mol / L and Pb 2+ A bar chart showing the fluorescence intensity changes at the maximum emission wavelength of 620 nm after adding 5 equivalents of other metal cations as analytes to the coexisting aqueous solution.

[0027] Figure 5 The concentration of fluorescent probe (III) is 1×10 -5 No Pb in aqueous solution at mol / L 2+ And Pb 2+ The graph shows the change in fluorescence emission intensity over time when it is present.

[0028] Figure 6 The concentration of fluorescent probe (III) is 1×10 -5 mol / L of Pb added 2+ The graph shows the change in fluorescence intensity with different pH values.

[0029] Figure 7 The concentration of fluorescent probe (III) is 1×10 -5 Fluorescence emission spectra of tetrahydrofuran / aqueous solutions at different ratios (mol / L). Excitation wavelength λ. ex =440nm;

[0030] Figure 8 The concentration of fluorescent probe (III) is 1×10 -5 Confocal fluorescence imaging of HeLa cells under different treatment conditions (mol / L). Excitation wavelength λ ex =440nm; Detailed Implementation

[0031] The present invention will now be described in further detail with reference to embodiments and accompanying drawings.

[0032] Example 1

[0033] Preparation of compound (II).

[0034] 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) and hexamethylenetetramine were dissolved in trifluoroacetic acid and reacted at 90 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, the solvent was evaporated to dryness, and the mixture was purified by silica gel column chromatography (eluents were dichloromethane and n-hexane) to give a white powder solid (II) in 28% yield. 1 H NMR (600MHz, CDCl3): δ (ppm) 9.35 (s, 1H), 7.01 (s, 1H), 7.17 (d, J = 8.32Hz, 3H), 7.70 (d, J = 8.52Hz, 1H), 7.54 (d, J =7.61Hz, 2H), 7.48 (t, J = 7.27Hz, 1H), 7.44 (t, J = 7.58Hz, 2H), 7.30 (m, J = 15.23, 7.62Hz, 5H), 7.25-7.22 (m, 3H).

[0035] Example 2

[0036] Quinolinyl imidazole Pb 2+ Preparation of fluorescent probe (III).

[0037] 4-Hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II) was dissolved in methanol with 1,2-dimethylquinoline iodide and piperidine. The mixture was reacted at 70 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature, the solvent was evaporated to dryness, and the mixture was purified by silica gel column chromatography (eluents were methanol and dichloromethane) to give a brownish-red powder solid (III) with a yield of 62%. 1 H NMR (600MHz, DMSO): δ (ppm) 9.00 (d, J = 8.98Hz, 1H), 8.52 (d, J = 9.03Hz, 1H), 8.46 (d, J=9.04Hz, 1H), 8.33 (d, J=7.83Hz, 1H), 8.18 (m, J=7.98Hz, 1H), 7.99-7.92 (m , 2H), 7.78 (m, J=8.56, 1.83Hz, 1H), 7.61 (d, J=1.69Hz, 1H), 7.47 (d, J=7.57Hz, 2 H), 7.04 (d, J=8.51Hz, 1H), 4.44 (s, 3H), 7.26-7.22 (m, 2H), 7.40-7.27 (m, 13H).

[0038] Example 3

[0039] Study on the selective recognition of different metal ions by quinolinyl imidazole fluorescent probes (III).

[0040] Prepare an accurate aqueous solution of 10 μM fluorescent probe (III). Figure 1As shown, 5 equivalents of different metal ions, such as Ca, are added to the test solution containing the fluorescent probe (III). 2+ Na + 、La 3+ Mn 2+ 、Ba 2+ Ag + Cu 2+ 、Zn 2+ Cd 2+ Hg 2+ Fe 3 + Fe 2+ Al 3+ Co 2+ Ni 2+ K + Mg 2+ Pb 2+ It was found that only by adding Pb 2+ Subsequently, the fluorescence intensity of fluorescent probe (III) at 620 nm was significantly enhanced, and the fluorescence intensity of the probe remained almost unchanged after the addition of other metal cations, indicating that, except for Pb... 2+ In addition, the other metal ions studied had almost no significant effect on the fluorescence spectrum of probe (III), indicating that the fluorescent probe (iii) is effective against Pb. 2+ It has high specificity and selectivity and can be used as a detection method for Pb. 2+ Specific fluorescent probes.

[0041] Example 4

[0042] Quinolinyl imidazole fluorescent probe (III) with Pb 2+ Graph showing the change in fluorescence intensity with increasing concentration.

[0043] The relationship between the fluorescence intensity of fluorescent probe (III) and Pb was further investigated through titration experiments. 2+ Linear relationship between concentrations. Pb was analyzed in an aqueous solution containing 10 μM fluorescent probe (III). 2+ Fluorescent titration, such as Figure 2 As shown, in the absence of Pb 2+ In the case of 440 nm excitation, the fluorescent probe (III) exhibits very weak fluorescence intensity at 620 nm; however, with the increase of Pb... 2+ As the concentration (0 μM–22 μM) increased, the fluorescence intensity of probe (III) at 620 nm gradually increased until it reached saturation. Figure 2 As shown. The maximum fluorescence emission intensity at 620 nm is selected as the ordinate, Pb 2+Using different concentrations as the abscissa, a linear regression equation was obtained through linear fitting: y = 35.63194x + 62.5016. The results are as follows... Figure 3 As shown, the linear correlation coefficient R 2 Greater than 0.99, fluorescent probe (III) and Pb 2+ It exhibits a good linear relationship (e.g.) Figure 3 It has a minimum detection limit of 0.28 μM, exhibits good sensitivity, and can be used for the detection of Pb within a certain concentration range. 2+ Quantitative analysis and detection.

[0044] Example 5

[0045] Quinolinyl imidazolium fluorescent probe (III) for detecting Pb 2+ The robustness to interference from different potential competing analytical objects.

[0046] To verify the effect of probe (III) on Pb 2+ In addition to specific identification, we also investigated the robustness of probe (III) to other potential analytes. For example... Figure 4 As shown, Pb was added to the solution of probe (III). 2+ After adding 20 μM, the probe (III) solution showed significant fluorescence enhancement at 620 nm. Subsequently, other metal ions (100 μM), containing Pb, were added. 2+ The fluorescence intensity of probe (III) solution did not change significantly, indicating that the presence of other potentially competing analytes does not interfere with the fluorescence intensity of probe (III) against Pb. 2+ For identification and detection, probe (III) targets Pb. 2+ It has good anti-interference capabilities.

[0047] Example 6

[0048] Quinolinyl imidazole fluorescent probe (III) recognizes Pb 2+ The fluorescence response time.

[0049] To determine the detection of Pb 2+ The response time was measured to determine the presence or absence of Pb in the aqueous solution of the fluorescent probe (III). 2+ Fluorescence changes over time, such as Figure 5 As shown. Without adding Pb. 2+ At the initial stage, the fluorescence intensity was very low, and the fluorescence intensity did not change with time; when Pb was added... 2+ Subsequently, the fluorescence intensity reached its maximum value within 20 seconds and then tended to stabilize, indicating that the fluorescent probe (III) has a short response time and high sensitivity, and can monitor Pb in real time. 2+ .

[0050] Example 7

[0051] The effect of different pH values ​​on the recognition of Pb by quinolinyl imidazole fluorescent probe (III) 2+ Impact

[0052] In order to obtain the detection of Pb 2+ The optimal pH range was determined, and the fluorescence intensity of the 10 μM fluorescent probe (III) was tested within the pH range of 2-12. Figure 6 As shown, when Pb is added 2+ After being incubated at 20 μM, the fluorescence intensity of probe (III) significantly increased over a wide pH range (3-7), indicating that probe (III) has a broad pH applicability.

[0053] Example 8

[0054] Aggregation-induced enhancement effect of quinolinyl imidazole fluorescent probe (III)

[0055] Different ratios of tetrahydrofuran / water solution containing 10 μM fluorescent probe (III) were used to measure its fluorescence emission spectra. For example... Figure 7 As shown, the fluorescence intensity at 620 nm gradually increases with the increase of the proportion of aqueous solution until excessive aggregation occurs when the water content reaches 99%, leading to quenching. This indicates that probe (III) has the ability to induce fluorescence enhancement in tetrahydrofuran / aqueous solution.

[0056] Example 9

[0057] Quinolinyl imidazole fluorescent probe (III) (10 μM) was present in HeLa cells at different Pb levels. 2+ Confocal fluorescence imaging under concentration conditions

[0058] HeLa cells were cultured in DMEM medium containing D-glucose and fetal bovine serum. The cells were divided into three groups and incubated with 10 μM probe (III) for 10 minutes, followed by the addition of 0 μM, 10 μM, and 20 μM Pb, respectively. 2+ The cells were incubated in the solution for 30 minutes, then washed three times with 1.0 mL PBS aqueous solution. Finally, the cells were examined using a high-resolution fluorescence confocal microscope, and the confocal fluorescence images were analyzed using Leica application software. The fluorescent dye penetrated the HeLa cells and was clearly imaged, demonstrating good biocompatibility and cell permeability. Confocal fluorescence imaging showed that the fluorescent dye entered the cells with increasing Pb content. 2+ As the concentration of [agent] increases, the fluorescence signal increases. Figure 8 These are confocal fluorescence images of HeLa cells under different treatment conditions.

Claims

1. A quinolinyl imidazolium Pb 2+ Fluorescent probe, characterized in that, Its chemical structure is shown in formula (III):

2. The quinolinyl imidazole Pb class according to claim 1 2+ A method for synthesizing a fluorescent probe, characterized in that, It was synthesized according to the following experimental steps; 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) is reacted with 1,2-dimethylquinoline iodide via a Duff reaction to produce 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II), which is then reacted with 1,2-dimethylquinoline iodide via a Knoevenagel condensation reaction catalyzed by piperidine to give compound (III).

3. The quinolinyl imidazole Pb according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, Includes the following steps: 1) Under light-protected conditions, 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) and hexamethylenetetramine were dissolved in trifluoroacetic acid and reacted at 90°C for 2 h to obtain compound (II); 2) 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II) was dissolved in methanol with 1,2-dimethylquinoline iodide and piperidine, and reacted at 70°C for 2 h to obtain compound (III).

4. The quinolinyl imidazole Pb according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, In step 1), the molar ratio of 2-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (I) to hexamethylenetetramine is 1:

1.

5. The quinolinyl imidazole Pb according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, In step 2), the molar ratio of 4-hydroxy-3-(1,4,5-triphenyl-1H-imidazol-2-yl)benzaldehyde (II) to 1,2-dimethylquinoline iodide is 1:1.

1.

6. The quinolinyl imidazole Pb according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, In step 1), the reaction mixture is heated to 90°C and stirred for 12 hours under light-protected conditions to obtain compound (II).

7. The quinolinyl imidazole Pb according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, In step 2), the reaction mixture is heated to 70°C and stirred for 2 hours to obtain compound (III).

8. The use of the fluorescent probe as described in claim 1, characterized in that... Pb is used in chemical or biological systems. 2+ The analysis is for testing purposes only and is not intended for the diagnosis or treatment of diseases.

9. The use according to claim 8, characterized in that, The fluorescent probe can perform Pb in aqueous solution. 2+ The quantitative and qualitative detection of Pb is described, specifically a fluorescence detection method; the fluorescent probe is effective against Pb. 2+ The detection limit is 0.28 μM.

10. The use according to claim 8, characterized in that, The fluorescent probe can detect Pb in cells. 2+ Changes in concentration.

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