Preparation method and application of triarylimidazole-benzothiazolyl Zn < 2 + > fluorescent probe

Abstract

The invention discloses a triarylimidazole-benzothiazolyl Zn < 2 + > fluorescent probe, which is synthesized by taking 3-benzothiazolyl-2-hydroxybenzaldehyde, benzil and 4-morpholinyl aniline as raw materials under the action of ammonium acetate through a Debus-Radziszewski imidazole synthesis method, and the chemical structural formula of the triarylimidazole-benzothiazolyl Zn < 2 + > fluorescent probe is as shown in the formula (I), the fluorescent probe disclosed by the invention has specific selectivity, extremely high sensitivity and very strong anti-interference capability on Zn < 2 + > in an ethanol solvent, and the detection limit can be as low as 28nM; the probe has good biocompatibility and can be used for detecting Zn < 2 + > in cells; the invention provides a simple and sensitive zinc ion detection probe which has great development potential in the fields of environment detection and biological imaging.

Description

Technical Field

[0001] This invention belongs to the field of organic small molecule fluorescent probes, specifically relating to a Zn based on imidazole-benzothiazole. 2+ Fluorescent probe. Background Technology

[0002] Zn 2+ Zinc is one of the essential trace elements for maintaining normal human life activities, playing a vital role in human growth and development, immunity, endocrine function, and reproductive heredity. In the human body, zinc is second only to iron in abundance, making it the second most abundant transition metal element. Existing research indicates that zinc in the human body... 2+ Both excessive and insufficient amounts of zinc can have adverse effects on human health. For example, a deficiency of zinc in an organism can lead to adverse health consequences. 2+ It can lead to various diseases such as growth retardation, anorexia, immune system dysfunction, and diabetes. Zn in the human body... 2+ Excessive intake can also lead to metabolic disorders, causing symptoms such as vomiting, headaches, diarrhea, and convulsions, and may damage brain neurons, leading to memory loss. Furthermore, many serious neurological diseases are also related to the body's zinc levels. 2+ It is associated with metabolic imbalances, including Alzheimer's disease, Parkinson's disease, cancer, and epilepsy. In addition, excessive Zn in the soil... 2+ It reduces the activity of soil microorganisms, inhibits plant growth, and can reduce crop yields. Therefore, it is necessary to design and develop a method for the rapid, effective, convenient, and accurate detection of Zn in biological and environmental samples. 2+ The method of content determination is of great significance.

[0003] However, because d 10 Electronic configuration characteristics lead to Zn 2+ Its sensitivity to spectra and magnetic fields is not as good as Fe. 2+ and Cu 2+ Furthermore, compared with methods such as atomic absorption spectroscopy, mass spectrometry, atomic emission spectroscopy, electrochemical analysis, and inductively coupled plasma atomic emission spectrometry, fluorescent probe technology has been widely used for Zn detection in organisms and the environment due to its advantages such as high selectivity, high sensitivity, short response time, good stability, and in-situ detection capabilities. 2+ Detection. However, Cd and Zn are in the same main group and have similar chemical properties, leading to Cd... 2+ Easily interferes with Zn 2+ Fluorescence detection. Therefore, precise design and synthesis of Zn with high sensitivity and selectivity are crucial. 2+ Fluorescent probes remain a significant challenge.

[0004] Benzothiazoles, due to their excellent physicochemical properties such as high quantum yield, high molar extinction coefficient, large Stokes shift, and good photostability, have attracted widespread attention from researchers in recent years for constructing fluorescent probes and chemical sensors. As a strong electron acceptor, the benzothiazole unit can not only effectively lower the LUMO energy level of the molecule but also enhance the fluorescence quantum yield and reduce non-radiative transitions through its rigid planar structure, thereby significantly improving luminescence performance. In recent years, many methods for detecting Zn have been developed... 2+ Benzothiazole-based fluorescent probes have been developed and reported. However, most benzothiazole-based fluorescent probes suffer from drawbacks such as poor selectivity, low sensitivity, and difficult synthesis, severely limiting their application in many fields. Therefore, the development of highly selective and highly sensitive Zn-based probes based on benzothiazole is a crucial research objective. 2+ Fluorescent probes remain of significant research value. However, many fluorescent probes exhibit aggregation-induced fluorescence quenching (ACQ) effects, greatly limiting their application in practical sample analysis. In contrast, aggregation-induced emission (AIE) can emit strong fluorescence in the aggregated state and shows high sensitivity to changes in the surrounding environment. Based on these considerations, this invention prepares a novel triarylimidazolium-benzothiazole-based probe for the detection of Zn. 2+ The fluorescent probe exhibits an AIE effect due to the introduction of triarylimidazole, while the nitrogen and hydroxyl oxygen atoms of benzothiazole can react with Zn. 2+ It performs coordination, thereby affecting Zn 2+ Selective identification is performed. This probe can specifically identify Zn. 2+ , with Zn 2+ After treatment, its fluorescence intensity is significantly enhanced, and the detection limit is low. Due to its advantages of fast response, high selectivity, and high sensitivity, this probe has great application potential. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention synthesizes a triarylimidazolium-benzothiazolyl Zn group through molecular design, exhibiting high selectivity, strong anti-interference ability, and low detection limit. 2+ Fluorescent probe.

[0006] This invention also provides the above-mentioned triarylimidazolium-benzothiazolyl Zn 2+ Methods for preparing fluorescent probes.

[0007] This invention also provides the above-mentioned triarylimidazolium-benzothiazolyl Zn 2+ Applications of fluorescent probes.

[0008] Technical solution: To achieve the above-mentioned objective, the technical solution of this invention is: a triarylimidazolium-benzothiazolyl Zn 2+ The fluorescent probe has the chemical structure shown in formula (I):

[0009]

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

[0011] (1) In the presence of trifluoroacetic acid (TFA), 2-(benzo[d]thiazol-2-yl)phenol reacts with hexamethylenetetramine (HMTA) via a Duff reaction to give compound (II);

[0012] (2) Compound (II) was synthesized from compound (II) with benzoyl and 4-morpholinoaniline in the presence of ammonium acetate using the Debus-Radziszewski imidazole synthesis method.

[0013] The above-mentioned triarylimidazole-benzothiazolyl Zn 2+ The specific synthetic route of the fluorescent probe is as follows:

[0014]

[0015] Step (1) is carried out by the following method: 2-(benzo[d]thiazol-2-yl)phenol and hexamethylenetetramine (HTMA) are dissolved in trifluoroacetic acid (TFA), and the mixture is heated under reflux and stirred for 10 h to obtain compound (II);

[0016] Step (2) is carried out by the following method: benzoyl, 4-morpholinoaniline and ammonium acetate are added to the mixture containing compound (II), and the mixture is heated to 110°C and stirred for 12 hours under light-protected conditions to obtain compound (I).

[0017] The triarylimidazol-benzothiazolyl Zn of the present invention 2+ Fluorescent probes for Zn in ethanol solution 2+ It has unique fluorescence response.

[0018] To prepare an ethanol solution of the fluorescent probe (I), and to investigate its selective recognition of different ions, various metal cations (Ag) were also prepared. + Al 3+ Ba 2+ Ca 2+ Cd 2+ Co 2+ Cr 3+ Cu 2+ Fe 2+ Fe 3+ Hg 2+ La 3+ Mg 2+ Mn2+ Na + Ni 2 + ,pb 2+ ) and anion (Br) - CH3COO - Cl - F - HPO4 2- HSO4 - MnO4 - PO4 3- SO4 2- Zn solution; Zn was studied by measuring UV-Vis absorption and fluorescence emission spectra. 2+ The effect of presence or absence on its optical performance, the results are as follows: Figure 1 As shown, the fluorescence emission spectrum intensity change reveals that the fluorescent probe (I) described in this invention is effective against Zn. 2+ Zn has unique fluorescence responsiveness. 2+ The addition of Zn significantly reduced the fluorescence emission intensity of the fluorescent probe (I) at 486 nm, while a new emission peak appeared at 434 nm, resulting in a 52 nm blue shift in fluorescence emission. Additionally, a certain amount of the fluorescent probe solution was taken, and Zn was gradually added... 2+ Up to 1.4 μM, the fluorescent probe (I) precipitates with Zn 2+ As the fluorescence intensity gradually increases, it can be observed that the original emission intensity at 486 nm gradually decreases, while a new emission peak appears at 434 nm, and the fluorescence intensity gradually increases, especially at Zn. 2+ The maximum fluorescence intensity was reached at 1.3 μM. Further increasing Zn... 2+ The content and fluorescence intensity remained almost unchanged, indicating that Zn has been reached. 2+ Saturation, the result is as follows Figure 2 As shown. The fluorescent probe (I) was added with Zn... 2+ During the process, fluorescence intensity was selected as the ordinate, and Zn 2+ Linear fitting was performed using the added equivalent as the abscissa, and the fluorescence intensity at 434 nm and 486 nm was compared with that of Zn. 2+ The concentration exhibits a good linear relationship in the range of 0-1.3 μM, with the linear equation at 434 nm being y = 259.7458x + 47.8206 (R0). 2 =0.9905), the linear equation at 486nm is y = -475.0178x + 735.8981 (R = 0.9905), 2 =0.986), the result is as follows Figure 3 As shown, this indicates that the fluorescent probe can be used for Zn within a certain range. 2+ Quantitative analysis and detection.

[0019] The triarylimidazolium-benzothiazolyl Zn of this invention 2+ Fluorescent probes for detecting Zn 2+ It exhibits excellent anti-interference properties against different ions, as shown in the following results. Figure 4 As shown, the addition of other ions has almost no effect on the fluorescence intensity of the fluorescent probe (I), thus confirming that the fluorescent probe (I) of the present invention is effective in detecting Zn in ethanol solution. 2+ It has unique fluorescence selectivity and strong resistance to interference from other ions.

[0020] The triarylimidazolium-benzothiazolyl Zn of this invention 2+ Fluorescent probes have the advantage of short response time, such as Figure 5 As shown, in Zn 2+ In the presence of [a specific substance], the fluorescence intensity of the probe reaches saturation after 15 seconds. This ultrafast response probe can be used for Zn [a specific application]. 2+ Real-time monitoring indicates that the probe has high sensitivity.

[0021] The triarylimidazolium-benzothiazolyl Zn of this invention 2+ The fluorescent probe targets Zn at pH values ​​between 3 and 10. 2+ The strong and stable fluorescence emission indicates that the probe has a wide pH range, which helps to improve the actual detection performance of the fluorescent probe.

[0022] The beneficial effects of this invention are: (1) the synthetic route of the fluorescent probe is simple, the reaction conditions are mild, and it is easy to prepare; (2) the fluorescent probe has good selectivity, strong anti-interference ability, high sensitivity, and the detection limit can be as low as 28 nM; (3) the probe has good biocompatibility and can be used for cell and organism Zn through fluorescence imaging. 2+ The probe is effective in the detection of [subjects] and has broad application prospects in analytical chemistry, environmental science, biology, and other fields. Attached Figure Description

[0023] Figure 1 The concentration of fluorescent probe (I) is 1×10 -6 Fluorescence intensity diagram of M after adding 10 equivalents of different ions to an ethanol solution of M;

[0024] Figure 2 The concentration of fluorescent probe (I) is 1×10 -6 Zn in ethanol solution of M 2+ Fluorescence titration graph. The vertical axis represents fluorescence emission intensity, and the horizontal axis represents emission wavelength. The excitation wavelength is 350 nm.

[0025] Figure 3 The fluorescent probe (I) uses different equivalents of Zn 2+Linear fitting graphs with ion concentration as the x-axis and fluorescence emission intensity at emission wavelengths of 434 nm and 486 nm as the y-axis; the x-axis represents the fluorescence intensity at the addition of Zn. 2+ The concentration, in units of 10 -6 M; Figure 4 The concentration of fluorescent probe (I) is 1×10 -6 M and 5 equivalents of Zn 2+ A bar chart showing the change in fluorescence intensity at 434 nm after adding 10 equivalents of other ions to a coexisting ethanol solution.

[0026] Figure 5 The concentration of fluorescent probe (I) is 1×10 -6 M contains no Zn in its ethanol solution. 2+ With Zn 2+ Graph showing the change in fluorescence emission intensity at 434 nm over time when present;

[0027] Figure 6 The concentration of fluorescent probe (I) is 1×10 -6 mol / L when adding Zn 2+ The graph shows the change in fluorescence intensity at 434 nm with different pH values.

[0028] Figure 7 The fluorescent probe (I) is applied to Zn containing different concentrations. 2+ Fluorescence imaging in HeLa cells. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings.

[0030] Example 1

[0031] Preparation of compound (II)

[0032] 2-(benzo[d]thiazol-2-yl)phenol (1.135 g, 5 mmol) and hexamethylenetetramine (HMTA) (700 mg, 5 mmol) were dissolved in trifluoroacetic acid (25 mL). After stirring under reflux for 10 h, the reaction mixture was cooled to room temperature and the pH was adjusted to neutral with sodium hydroxide solution. The mixture was filtered to obtain a pale yellow solid, which was extracted with saturated sodium chloride and ethyl acetate. The solvent was removed by vacuum distillation to obtain a pale yellow solid. The crude product was then purified by silica gel column chromatography using petroleum ether / ethyl acetate (v / v = 5:1) as eluent to give compound (II) in 33% yield. 1H NMR (600MHz, DMSO-d6, ppm) δ13.02 (s, 1H), 10.37 (s, 1H), 8.42-8.41 (m, 1H), 8.23 ​​(d, J=8.4Hz, 1H), 8.14 (d, J=8.4Hz, 1H), 7.94 (d, J=7.8Hz, 1H), 7.61 (t, J=14.4Hz, 1H), 7.53 (t, J=14.4Hz, 1H), 7.24 (d, J=15.6Hz, 1H).

[0033] Example 2

[0034] Preparation of triarylimidazolium-benzothiazolium fluorescent probe (I)

[0035] Compound (II) (100 mg, 0.39 mmol), benzoyl (124 mg, 0.59 mmol), 4-morpholinoaniline (105 mg, 0.59 mmol), ammonium acetate (300 mg, 3.9 mmol), and acetic acid (2 mL) were sequentially placed into a round-bottom flask. The reaction mixture was stirred at 110 °C for 12 h under light-protected conditions until TLC showed complete disappearance of compound (II). After cooling to room temperature, the reaction mixture was poured into 200 mL of an ice-water mixture to give a pale yellow solid. The solid was purified by silica gel column chromatography using ethyl acetate / petroleum ether (v / v = 3:7) to give fluorescent probe (I) in 30% yield. 1 H NMR (600MHz, CDCl3, ppm) δ8.34 (d, J=7.8Hz, 1H), 8.06 (d, J=8.4Hz, 1H), 7.97 (d, J=7.8Hz, 1H), 7.57 (d, J=7.2Hz, 2H), 7 .51-7.48 (m, 1H), 7.40-7.37 (m, 1H), 7.30 (d, J=3.0Hz, 1H), 7.29-7.28 (t, J=3Hz, 1H), 7.28 (d, J=1.2Hz, 1H), 7.27 (s, 1 H), 7.25 (d, J=2.4Hz, 1H), 7.25-7.22 (m, 1H), 7.18-7.17 (m, 2H), 7.08-7.07 (d, J=8.4Hz, 2H), 6.91-6.90 (d, J=7.2Hz, 1 H), 6.83-6.81 (d, J=9.0Hz, 2H), 6.74-6.71 (t, J=15.6Hz, 1H), 3.86-3.84 (t, J=9.6Hz, 4H), 3.19-3.17 (d, J=9.6Hz, 4H).

[0036] Example 3

[0037] Selectivity study of triarylimidazolium-benzothiazolium fluorescent probe (I) for different ions

[0038] Prepare an accurate ethanol solution of the 1.0 μM fluorescent probe (I). For example... Figure 1 As shown, when the excitation wavelength is 350 nm, the fluorescent probe (I) solution exhibits a strong fluorescence emission peak at 486 nm. Ten equivalents of different ions (Ag) were added to the test solution containing the fluorescent probe (I). + Al 3+ Ba 2+ Ca 2+ Cd 2+ Co 2+ Cr 3+ Cu 2+ Fe 2+ Fe 3+ Hg 2+ La 3+ Mg 2+ Mn 2+ Na + Ni 2+ Pb 2+ , Br - CH3COO - Cl - F - HPO4 2- HSO4 - MnO4 - PO4 3- SO4 2- ), discovered that adding Zn 2+ Subsequently, the emission at 486 nm significantly decreased, while a new emission peak appeared at 434 nm, showing a noticeable blue shift of 52 nm. However, when other metal cations and anions were added, the fluorescence spectrum of probe (I) did not change significantly, indicating that probe (I) is sensitive to Zn. 2+ It exhibits superior selective responsiveness. The above results demonstrate that the fluorescent probe (I) responds well to Zn in complex analyte environments. 2+ It has excellent specificity recognition capabilities; it can be used as a detector for Zn. 2+ Specific fluorescent probes.

[0039] Example 4

[0040] Triarylimidazole-benzothiazolylZn 2+ Fluorescent probe (I) with Zn 2+ The fluorescence intensity change at 434 nm with increasing concentration was shown in the figure. Further investigation was conducted using titration experiments to explore the relationship between the fluorescence intensity of the fluorescent probe (I) and Zn. 2+Linear relationship between concentrations. Zn was analyzed in an ethanol solution containing 1.0 μM fluorescent probe (I). 2+ Fluorescent titration, such as Figure 2 As shown, in the absence of Zn 2+ Under these conditions, when excited at a wavelength of 350 nm, the fluorescent probe (I) exhibits significant fluorescence intensity at 486 nm; however, with the decrease in Zn... 2+ With the addition of (0-1.4 μM), the fluorescence intensity of probe (I) at 486 nm gradually decreased, while the emission peak intensity at 434 nm gradually increased until it reached its maximum value, as shown below. Figure 2 As shown. Additionally, in Zn 2+ Within the concentration range of 0-1.3 μM, the maximum fluorescence emission intensity at 434 nm or 486 nm was selected as the ordinate, and Zn 2+ Using different concentrations as the abscissa, a linear fit was performed, and the fluorescence intensity of probe (I) was correlated with Zn. 2+ They exhibit a good linear relationship, with linear correlation coefficients of 0.9860 and 0.9905, corresponding to the linear relationship equations at 486nm and 434nm, respectively. Figure 3 The detection limit is 28 nM, indicating high sensitivity. These results demonstrate that probe (I) is effective for Zn... 2+ The detection exhibits high selectivity and sensitivity, and can be used for the determination of Zn within a certain concentration range. 2+ Quantitative analysis and detection.

[0041] Example 5

[0042] Triarylimidazole-benzothiazolylZn 2+ Fluorescent probe (I) in the detection of Zn 2+ Anti-interference properties against different ions

[0043] To verify the effect of probe (I) on Zn 2+ In addition to its specific and selective recognition, we also investigated the anti-interference properties of probe (I) against other related analytes, and the results are as follows: Figure 4 As shown, Zn was added to the solution of probe (I). 2+ The probe (I) solution exhibited significant fluorescence enhancement at 434 nm; subsequent addition of other ions (10 μM) did not result in significant changes in the fluorescence intensity of the probe (I) solution. This indicates that the presence of other potentially competing analytes does not interfere with the fluorescence intensity of probe (I) on Zn. 2+ The identification and detection of Zn, probe (I) for Zn 2+ It has strong anti-interference capabilities.

[0044] Example 6

[0045] Triarylimidazolium-benzothiazolium fluorescent probe (I) recognizes Zn2+ fluorescence response time

[0046] To determine the detection of Zn 2+ The response time was measured by testing the 1.0 μM fluorescent probe (I) in an ethanol solution without Zn. 2+ With Zn 2+ Fluorescence changes over time, results are as follows Figure 5 As shown, without adding Zn 2+ At that time, F 434nm / F 486nm Very low and does not change over time; when Zn is added 2+ Afterwards, the fluorescent probe (I) was in F 434nm / F 486nm The fluorescence intensity at the point increased instantaneously and reached saturation and stabilized after 15 seconds, indicating that probe (I) recognizes Zn. 2+ With high sensitivity and a short response time, this fluorescent probe (I) can be used for real-time monitoring of Zn. 2+ .

[0047] Example 7

[0048] Different pH values ​​affect the recognition of Zn by the triarylimidazolium-benzothiazolium-based fluorescent probe (I). 2+ Impact

[0049] To determine the detection of Zn 2+ The optimal pH range was determined, and the fluorescence intensity of a 1 μM fluorescent probe (I) was tested within the pH range of 2-12. Figure 6 As shown, no Zn was added. 2+ At that time, the fluorescence intensity of probe (I) was higher than that of (F). 434nm / F 486nm There was essentially no significant change within the pH range of 3-10, but when Zn was added... 2+ After (10 μM), the fluorescence intensity of probe (I) was higher than that of (F) over a wide pH range (4-9). 434nm / F 486nm The effect was significantly enhanced and remained almost unchanged in the pH range of 3-10, indicating that probe (I) has a wide pH range of applicability.

[0050] Example 8

[0051] Triarylimidazolium-benzothiazolium fluorescent probe (I) applied to Zn in HeLa cells 2+ Detection using fluorescence imaging.

[0052] The detection of Zn by fluorescent probe (I) in cells was investigated using biofluorescence imaging. 2+ Performance. For example... Figure 7As shown, in the first group of experiments, HeLa cells were incubated with fluorescent probe (I) (10 μM) at 37°C for 30 minutes, and the cells emitted red fluorescence. In the control experiment, HeLa cells were treated with fluorescent probe (I) 10 μM for 30 minutes, and then treated with 7.5 and 15.0 μM Zn, respectively. 2+ Incubate for 30 minutes; from Figure 7 It can be seen that with Zn 2+ With increasing concentration, the intracellular red fluorescence signal weakens, while the green fluorescence gradually increases, and obvious green fluorescence can be observed in the cells, indicating that the fluorescent probe (I) can be applied to intracellular Zn. 2+ Imaging can detect Zn within living cells. 2+ This probe exhibits selective recognition and good biocompatibility and cell membrane penetration.

Claims

1. A triarylimidazolium-benzothiazolyl Zn 2+ Fluorescent probe, characterized in that, Its chemical structural formula is shown in formula (I):

2. The triarylimidazolium-benzothiazolyl Zn of claim 1 2+ A method for synthesizing a fluorescent probe, characterized in that, It was synthesized according to the following experimental steps; (1) Compound (II) was obtained by reacting 2-benzothiazolylphenol and hexamethylenetetramine with trifluoroacetic acid via the Duff reaction. Its structural formula is as follows: (2) Under light-protected conditions, using compound (II), benzoyl, and 4-morpholinoaniline as raw materials, a triarylimidazolium-benzothiazolium-based fluorescent probe compound (I) was synthesized via the Debus-Radziszewski imidazole synthesis method in the presence of ammonium acetate. Its structural formula is as follows:

3. The triarylimidazolium-benzothiazolyl Zn according to claim 2 2+ A method for preparing fluorescent probes, characterized in that, 2-Benzothiazolylphenol and hexamethylenetetramine were dissolved in trifluoroacetic acid and heated under reflux and stirred for 10 h to obtain compound (II); characterized in that the molar ratio of 2-benzothiazolylphenol to hexamethylenetetramine was 1:

1.

4. The method for preparing the triarylimidazolium-benzothiazolyl Zn2+ fluorescent probe according to claim 2, characterized in that, Step (2) is carried out by the following method: benzoyl, 4-morpholinoaniline and ammonium acetate are added to an acetic acid solution containing compound (II), and the mixture is heated to 110°C and stirred for 12 hours under light-protected conditions to obtain compound (I).

5. The use of the fluorescent probe as described in claim 1, characterized in that... Zn used in chemical or biological systems 2+ Detection and analysis.

6. The application according to claim 5, characterized in that, The fluorescent probe described above can perform Zn in ethanol solution. 2+ Qualitative and quantitative detection, wherein the detection is fluorescence detection.

7. The application according to claim 5, characterized in that, The fluorescent probe can detect Zn in cells. 2+ The application is not intended for the diagnosis or treatment of diseases, but rather to reflect changes in concentration.

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