A 2-aminothiazolyl rhodamine 6G derivative, its preparation method and application

Abstract

The present invention belongs to the field of advanced materials technology, and relates to a new rhodamine derivative, specifically to a 2-aminothiazolyl rhodamine 6G derivative and its preparation method and application. The present invention uses rhodamine 6G and 2-aminothiazole as raw materials to prepare the 2-aminothiazolyl rhodamine 6G derivative RGAT in a one-step reaction. On the one hand, RGAT shows excellent selectivity and high sensitivity to Fe<supgt;3+< / supgt>, with a significant fluorescence enhancement, a wide linear range for Fe<supgt;3+< / supgt>, and a good linear relationship with the Fe<supgt;3+< / supgt> concentration in the range of 0-50 µM of Fe<supgt;3+< / supgt> concentration, and the detection limit is as low as 2.4 nM. On the other hand, RGAT has antibacterial properties superior to commercially available bleach against both Gram-positive and Gram-negative bacteria, and RGAT has very low cytotoxicity, showing good application prospects in the fields of environmental monitoring and biomedicine.

Description

Technical Field

[0001] The present invention belongs to the field of advanced materials technology, and relates to a new rhodamine derivative, specifically to a 2-aminothiazolyl rhodamine 6G derivative and its preparation method and application. Background Art

[0002] Rhodamine and its derivatives are a class of classical fluorescent dyes. Due to their excellent photophysical properties such as large molar extinction coefficient, high fluorescence quantum yield, and long absorption and emission wavelengths, they are widely used as spectral probes in fields such as analytical science, environmental detection, and biomedicine [Wang Y, Wang X, Ma W, et al. Recent developments inrhodamine-based chemosensors: A review of the years 2018–2022[J].Chemosensors, 2022, 10(10): 399].

[0003] Fe 3+ is an essential trace element for maintaining life processes. Excess or deficiency will affect human health. Therefore, the monitoring of Fe 3+ is very important. The spectral probe method is a common method for monitoring metal ions, and the research on Fe 3+ spectral probes is very active. For example, Yin et al. synthesized a rhodamine B-based Fe 3+ fluorescent probe, and the fluorescence increased by about 193 times after binding to Fe 3+ in methanol. The linear range of Fe 3+ was 4 - 12 μM, and the detection limit was 4.3 μM [Yin W, Cui H, Yang Z, et al. Facilesynthesis and characterization of rhodamine-based colorimetric and “off–on”fluorescent chemosensor for Fe 3+ [J]. Sensors and Actuators B: Chemical, 2011,157(2): 675-680]. She et al. synthesized a rhodamine-type Fe 3+ fluorescent probe, and the fluorescence intensity increased by 64 times after binding to Fe 3+ in methanol solution. The linear range of Fe 3+The linear range is 5 - 20 μM, and the detection limit is 5 μM [She M, Yang Z, Yin B, etal. A novel rhodamine-based fluorescent and colorimetric “off–on” chemosensorand investigation of the recognizing behavior towards Fe 3+ [J]. Dyes andPigments, 2012, 92(3): 1337 - 1343]. Zhang et al. first chlorinated rhodamine B with phosphoryl oxychloride and then condensed it with 2-aminothiazole by dehydrogenation of hydrogen chloride to synthesize an Fe 3+ spectral probe. In CH3CN / H2O (1 / 1, v / v), the fluorescence intensity increased by about 20 times after binding to Fe 3 + The linear range is 2 - 7 μM [Zhang F, Gao Q, Zhao J, et al.Design and synthesis of a novel rhodamine-based chemosensor and recognitionstudy to Fe 3+ [J]. Heterocyclic Communications, 2016, 22(1): 37 - 42]. 3+ [J]. Heterocyclic Communications, 2016, 22(1): 37 - 42].

[0004] For these reported Fe 3+ spectral probes, some of them require volatile and highly toxic organic solvents such as methanol in the detection medium, some have complex synthesis processes, narrow linear ranges, some have small fluorescence enhancement multiples, high detection limits, and are not sensitive enough; moreover, these rhodamine derivatives only have the single function of detecting Fe 3+ . SUMMARY OF THE INVENTION

[0005] If rhodamine derivatives can have multiple functions simultaneously, it is more significant than only being able to detect one metal ion. Therefore, the research on multifunctional rhodamine derivatives has attracted more and more attention. Currently, more reports are about a probe recognizing multiple ions or molecules, which belong to the multifunction in the same field. There is no report on rhodamine derivatives with multifunctions in different fields. In the present invention, a novel multifunctional rhodamine 6G derivative RGAT was synthesized by a one-step method. On the one hand, RGAT shows excellent selectivity and high sensitivity to Fe 3+ , with significant fluorescence enhancement. The Fe 3+ linear range is wide, in the range of 0 - 50 µM of Fe3+ In the concentration range, it has a good linear relationship with the Fe 3+ concentration, and the detection limit is as low as 2.4 nM. On the other hand, RGAT has better antibacterial performance against both Gram-positive and Gram-negative bacteria than commercially available bleach water, and the cytotoxicity of RGAT is very low, showing its good application prospects in the fields of environmental monitoring and biomedicine.

[0006] The present invention adopts the following technical solutions.

[0007] A 2-aminothiazolyl rhodamine 6G derivative, whose chemical structural formula is as follows:

[0008] .

[0009] The present invention discloses a preparation method of the above 2-aminothiazolyl rhodamine 6G derivative, which includes the following steps: using rhodamine 6G and 2-aminothiazole as raw materials to prepare the 2-aminothiazolyl rhodamine 6G derivative by a one-step reaction.

[0010] In the present invention, the reaction is carried out in an inert atmosphere. Preferably, the inert atmosphere includes a nitrogen atmosphere.

[0011] In the present invention, the reaction temperature is 50-100 °C and the time is 2-20 hours; preferably, the reaction temperature is 65-85 °C and the time is 7-14 hours.

[0012] The present invention discloses the application of the above 2-aminothiazolyl rhodamine 6G derivative as an Fe 3+ spectral probe.

[0013] The present invention discloses the application of the above 2-aminothiazolyl rhodamine 6G derivative in the preparation of an Fe 3+ detection reagent.

[0014] The present invention discloses the application of the above 2-aminothiazolyl rhodamine 6G derivative as an antibacterial agent.

[0015] The present invention discloses the application of the above 2-aminothiazolyl rhodamine 6G derivative in the preparation of an antibacterial reagent.

[0016] The present invention discloses a method for Fe 3+ detection, which includes the following steps: using the above 2-aminothiazolyl rhodamine 6G derivative to detect Fe 3+ . Specifically, it includes the following steps: mixing the above 2-aminothiazolyl rhodamine 6G derivative with the system to be detected, and detecting Fe 3+ by spectroscopy.

[0017] In the present invention, the spectroscopic detection includes one or both of ultraviolet-visible spectroscopic detection and fluorescence spectroscopic detection.

[0018] In the present invention, the solvent system for spectral detection includes an organic solvent and water; among them, the organic solvent includes acetonitrile, N,N-dimethylformamide (DMF), etc., and acetonitrile is preferred.

[0019] Preferably, the volume ratio of the organic solvent to water is 1∶(1 - 10); more preferably, the volume ratio of the organic solvent to water is 1∶(1 - 8); more preferably, the volume ratio of the organic solvent to water is 1∶(2 - 6).

[0020] The present invention discloses an antibacterial method, which includes the following steps of using the above-mentioned 2-aminothiazolyl rhodamine 6G derivative for antibacterial. Specifically, it includes the following steps of mixing the above-mentioned 2-aminothiazolyl rhodamine 6G derivative with a system containing bacteria to achieve antibacterial.

[0021] In the present invention, the bacteria include one or more of Gram-positive bacteria and Gram-negative bacteria.

[0022] Specifically, Gram-positive bacteria include Staphylococcus, Enterococcus, Streptococcus, Bacillus, Corynebacterium, etc.; Gram-negative bacteria include Klebsiella, Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, Salmonella, etc. As an example, the present invention has better antibacterial performance against Bacillus thuringiensis and Serratia marcescens than commercially available bleach, and the RGAT cytotoxicity is very low, showing its good application prospects in the fields of environmental monitoring and biomedicine.

[0023] Currently, there are more reports on one probe recognizing multiple ions or molecules, which belong to the same field of multi-functionality. There are no reports on rhodamine derivatives with multi-functionality in different fields. The present invention synthesizes a novel multi-functional rhodamine 6G derivative RGAT by a one-step method. On the one hand, RGAT shows excellent selectivity and very high sensitivity to Fe 3+ with a significant fluorescence enhancement. The linear range of Fe 3+ is wide. In the concentration range of 0 - 50 µM of Fe 3+ it shows a good linear relationship with the concentration of Fe 3+ and the detection limit is as low as 2.4 nM. On the other hand, RGAT has better antibacterial performance against both Gram-positive bacteria and Gram-negative bacteria than commercially available bleach, and the RGAT cytotoxicity is very low, showing its good application prospects in the fields of environmental monitoring and biomedicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the synthesis of 2-aminothiazolyl rhodamine 6G derivative (RGAT);

[0025] Figure 2Response photos of RGAT (10 µM) to 17 metal ions in the DMF / H2O (1 / 99, v / v) solvent system. Top: natural light; bottom: 365 nm ultraviolet light. Metal ion concentration: 50 µM.

[0026] Figure 3 Selectivity of the ultraviolet-visible spectrum (a) and fluorescence spectrum (b) of RGAT to metal ions. Solvent: DMF / H2O (1 / 99, v / v); RGAT concentration: 10 µM; metal ion concentration: 50 µM; excitation wavelength: 530 nm; slit width: 2.5 nm.

[0027] Figure 4 Response photos of RGAT (10 µM) to 17 metal ions in the CH3CN / H2O (20 / 80, v / v) solvent system. Top: natural light; bottom: 365 nm ultraviolet light. Metal ion concentration: 50 µM.

[0028] Figure 5 Selectivity of the ultraviolet-visible spectrum (a) and fluorescence spectrum (b) of RGAT to metal ions. Solvent: CH3CN / H2O (20 / 80, v / v); RGAT concentration: 10 µM; metal ion concentration: 50 µM; excitation wavelength: 530 nm; slit width: 2.5 nm.

[0029] Figure 6 Ultraviolet-visible absorption (a) and fluorescence intensity (b) spectra of RGAT for different concentrations of Fe 3+ . Inset: relationship between the concentration of Fe 3+ and the absorbance at 530 nm / fluorescence intensity at 554 nm; solvent: CH3CN / H2O (20 / 80, v / v); RGAT concentration: 10 µM; metal ion concentration: 0 - 150 µM; excitation wavelength: 530 nm, slit width: 2.5 nm.

[0030] Figure 7 Effect of coexisting metal ions on the absorbance (a) of the RGAT-Fe 3+ solution at 530 nm and fluorescence intensity (b) at 554 nm; concentration: RGAT is 10 µM, Fe 3+ is 50 µM; solvent system: CH3CN / H2O (20 / 80, v / v); absorption wavelength: 530 nm, excitation wavelength: 530 nm, slit width: 2.5 nm, fluorescence wavelength: 554 nm.

[0031] Figure 8 For RGAT-Fe 3+Time responsiveness of the ultraviolet-visible absorption (a) and fluorescence intensity (b) of the solution; concentration: RGAT is 10 µM, Fe 3+ is 50 µM; solvent system: CH3CN / H2O (20 / 80, v / v); absorption wavelength: 530 nm, excitation wavelength: 530 nm, slit width: 2.5 nm, fluorescence wavelength: 554 nm.

[0032] Figure 9 For the detection of Fe by RGAT 3+ ultraviolet-visible absorption (a) and fluorescence spectrogram (b); concentration: RGAT is 10 µM, Fe 3+ is 50 µM, EDTA is 60 µM; solvent: CH3CN / H2O (20 / 80, v / v); excitation wavelength: 530 nm, slit width: 2.5 nm; inset: color change under visible light and fluorescence change under 365 nm ultraviolet light after adding Fe 3+ to the CH3CN / H2O (20 / 80, v / v) solution of RGAT and then adding an excessive amount of EDTA solution, a: natural light, b: 365 nm ultraviolet light.

[0033] Figure 10 Survival rates of cik cells incubated with 20, 40, 60 μM of RGAT.

[0034] Figure 11 Photographs of the quantitative killing experiment of the suspension of RGAT, where a: Bacillus thuringiensis + sterile water; b: Bacillus thuringiensis + DMSO; c, d, e, f, g: Bacillus thuringiensis + RGAT solution, where the RGAT concentrations are 1.6 (c), 1.7 (d), 1.8 (e), 1.9 (f), 2.0 (g) mg / mL; h: Bacillus thuringiensis + bleach, bleach concentration is 2.0 mg / mL.

[0035] Figure 12 Photographs of the quantitative killing experiment of the suspension of RGAT; among them, a: Serratia marcescens + sterile water; b: Serratia marcescens + DMSO; c, d, e, f, g: Serratia marcescens + RGAT solution, where the RGAT concentrations are 1.6 (c), 1.7 (d), 1.8 (e), 1.9 (f), 2.0 (g) mg / mL; h: Serratia marcescens + bleach, bleach concentration is 2.0 mg / mL. Detailed implementation manners

[0036] The present invention synthesizes a novel multifunctional rhodamine 6G derivative RGAT by a one-step method. On the one hand, RGAT shows excellent selectivity and very high sensitivity to Fe 3+ and exhibits a significant fluorescence enhancement. Fe3+ It has a wide linear range and shows a good linear relationship with the concentration of Fe in the range of 0 - 50 μM. 3 + concentration, and the detection limit is as low as 2.4 nM. On the other hand, RGAT has antibacterial properties superior to commercially available bleach for both Gram-positive and Gram-negative bacteria, and its cytotoxicity is very low, showing good application prospects in the fields of environmental monitoring and biomedicine. 3+ 3+

[0037] See Figure 1 , in the present invention, rhodamine 6G and 2-aminothiazole are used as raw materials to react and prepare 2-aminothiazolyl rhodamine 6G derivatives. Specifically, rhodamine 6G and sodium acetate (or N,N-diisopropylethylamine) are dissolved in a solvent, 2-aminothiazole is added under N2 protection, and the mixture is refluxed. After the reaction is completed, the reaction solution is cooled to room temperature, the solvent is removed under reduced pressure, and the crude product is separated by silica gel column chromatography to obtain a granular product with a yield of 13.2% - 71.1%.

[0038] In the present invention, the molar ratio of rhodamine 6G to 2-aminothiazole is 1∶(0.5 - 3), preferably 1∶(1 - 2.5).

[0039] In the present invention, the reflux reaction time is 1 - 20 hours, preferably 5 - 15 hours.

[0040] In the present invention, the molar ratio of rhodamine 6G to sodium acetate is 1∶(1 - 3), preferably 1∶(1.5 - 2.5).

[0041] In the present invention, the molar ratio of rhodamine 6G to N,N-diisopropylethylamine is 1∶(1 - 3), preferably 1∶(1.5 - 2.5).

[0042] In the present invention, the solvent includes acetonitrile and ethanol.

[0043] The creativity of the present invention lies in the design and synthesis of a novel rhodamine 6G derivative, which is a rhodamine 6G derivative that can be used as both an Fe 3+ spectral probe and has antibacterial properties.

[0044] The present invention discloses the chemical structure, synthesis method of rhodamine 6G derivatives, and the application of this rhodamine 6G derivative in the field of Fe 3+ spectral probes, as well as the application of this rhodamine 6G derivative in the antibacterial field. Compared with the prior art, the present invention has achieved positive effects and advantages: RGAT is simple to synthesize and has multiple functions in different fields: it can recognize Fe 3+and antibacterial; moreover, RGAT as Fe 3+ The spectral probe has good selectivity and high sensitivity; in particular, RGAT has almost no cytotoxicity; unexpectedly, RGAT has excellent antibacterial properties, superior to commercially available bleach.

[0045] The following illustrates the technical progress of the present invention through specific experiments. The raw materials (cells, bacteria) used are all commercially available products, and the specific preparation operations and performance tests are conventional techniques. The preparation of metal ion solutions is a conventional technique in the art and does not affect those skilled in the art's understanding of the technical effects of the present invention. Prepare Fe 3+ 、Fe 2+ 、Cr 3+ 、Ag + 、Cu 2+ 、Al 3+ 、Na + 、K + 、Mg 2+ 、Ca 2+ 、Hg 2+ 、Zn 2+ 、Co 2+ 、Cd 2+ 、Pb 2+ 、Mn 2+ 、Ni 2+ The compounds corresponding to the metal ion solutions: anhydrous FeCl3, FeCl2·7H2O, CrCl3·6H2O, AgNO3, CuSO4·5H2O, AlCl3·6H2O, NaCl, KCl, MgCl2, CaCl2, HgCl2, Zn(NO3)2·6H2O, CoCl2·6H2O, CdCl2·2.5H2O, Pb(NO3)2, MnSO4·H2O, Ni(NO3)2·6H2O.

[0046] Example 1 Synthesis of RGAT

[0047] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) and dissolve them in 8 mL of acetonitrile. Stir conventionally under N2 protection, then add 2-aminothiazole (0.02 g, 0.2 mmol), and reflux at 75 °C for 11 h to stop the reaction; let the reaction solution cool to room temperature naturally, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography with ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 35.2 mg of light pink granular product with a yield of 71.1%.

[0048] The molecular formula of RGAT is C 29 H 28N4O2S, with a molecular weight M of 496.00. Mass spectrometry analysis found that the peak with a mass-to-charge ratio of 497.09 was the [M+H] of RGAT + molecular ion peak. Then, infrared spectroscopy analysis was performed on the sample, and characteristic absorption peaks (ν / cm -1 ) of the RGAT structure could be seen: ν(C-O-C): 1243.96; ν(Ar-H): 1416.07, 1519.64, 745.80; ν(C-N): 1376.05; ν(C=O): 1621.09; ν(C=N): 1693.44; ν(C-S-C): 1059.31; ν(CH3,CH2): 2998.47, 2914.62. Further, nuclear magnetic resonance hydrogen spectrum analysis was performed on the sample, and the following data were obtained: 1 H NMR (400 MHz, CDCl3, δ / ppm): 8.04 (dd, J = 5.9, 1H, PhH), 7.57 - 7.49 (t, J = 3.5 Hz, 2H, PhH, SCHCHN), 7.22 (d, J =3.3 Hz, 1H, PhH)), 7.15 - 7.10 (m, 1H, SCHCHN), 6.79 (d, J = 3.2 Hz, 1H, PhH),6.42 (s, 2H, PhH), 6.17 (s, 2H, PhH), 3.45 (s, 2H, CH3CH2NH), 3.24 - 3.16 (m,4H, CH3CH2NH), 1.83 (s, 6H, PhCH3), 1.31 (t, J = 7.2 Hz, 6H, CH3CH2NH). The results of mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance hydrogen spectrum analysis proved that the sample was RGAT.

[0049] Example 2 Synthesis of RGAT

[0050] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol), dissolve them in 8 mL of ethanol, stir under N2 protection, add 2-aminothiazole (0.015 g, 0.15 mmol), reflux at 75 °C for 11 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 6.5 mg of light pink granular product with a yield of 13.2%.

[0051] Example 3: Synthesis of RGAT

[0052] Dissolve rhodamine 6G (0.048 g, 0.1 mmol) and N,N - diisopropylethylamine (DIPEA) (35 μL, 0.2 mmol) in 8 mL of acetonitrile. After stirring under N2 protection, add 2 - aminothiazole (0.015 g, 0.15 mmol). Reflux the reaction mixture at 75 °C for 11 h. Stop the reaction. Cool the reaction solution to room temperature and remove the solvent under reduced pressure. The crude product is separated by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 18.3 mg of a light pink granular product with a yield of 36.8%.

[0053] Example 4: Synthesis of RGAT

[0054] Dissolve rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) in 8 mL of acetonitrile. Stir under N2 protection and add 2 - aminothiazole (0.025 g, 0.25 mmol). Reflux the reaction mixture at 75 °C for 11 h. Stop the reaction. Cool the reaction solution to room temperature and remove the solvent under reduced pressure. The crude product is separated by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 34.4 mg of a light pink granular product with a yield of 69.4%.

[0055] Example 5: Synthesis of RGAT

[0056] Dissolve rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) in 8 mL of acetonitrile. Stir under N2 protection and then add 2 - aminothiazole (0.01 g, 0.1 mmol). Reflux the reaction mixture at 75 °C for 11 h. Stop the reaction. Cool the reaction solution to room temperature and remove the solvent under reduced pressure. The crude product is separated by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 28.6 mg of a light pink granular product with a yield of 57.7%.

[0057] Example 6: Synthesis of RGAT

[0058] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) and dissolve them in 8 mL of acetonitrile. After stirring under N2 protection, add 2-aminothiazole (0.015 g, 0.15 mmol). React under reflux at 75 °C for 11 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 32.1 mg of a light pink granular product with a yield of 64.7%.

[0059] Example VII Synthesis of RGAT

[0060] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) and dissolve them in 8 mL of acetonitrile. Stir under N2 protection, add 2-aminothiazole (0.02 g, 0.2 mmol), react under reflux at 65 °C for 11 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 30.8 mg of a light pink granular product with a yield of 62.1%.

[0061] Example VIII Synthesis of RGAT

[0062] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) and dissolve them in 8 mL of acetonitrile. Stir under N2 protection, add 2-aminothiazole (0.02 g, 0.2 mmol), react under reflux at 85 °C for 11 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 32.5 mg of a light pink granular product with a yield of 65.6%.

[0063] Example IX Synthesis of RGAT

[0064] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol) and dissolve them in 8 mL of acetonitrile. Stir under N2 protection, add 2-aminothiazole (0.02 g, 0.2 mmol), react under reflux at 75 °C for 7 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure, and separate the crude product by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 32.9 mg of a light pink granular product with a yield of 66.3%.

[0065] Example Ten: Synthesis of RGAT

[0066] Take rhodamine 6G (0.048 g, 0.1 mmol) and sodium acetate (CH3COOONa) (0.016 g, 0.2 mmol), dissolve them in 8 mL of acetonitrile. After stirring under N2 protection, add 2-aminothiazole (0.02 g, 0.2 mmol). React under reflux at 75 °C for 14 h, stop the reaction, cool the reaction solution to room temperature, remove the solvent under reduced pressure. The crude product is separated by silica gel column chromatography using ethyl acetate / petroleum ether = 1 / 4 (v / v) as the eluent to obtain 34.8 mg of a light pink granular product with a yield of 70.2%.

[0067] Example Eleven: Response of RGAT to Metal Ions

[0068] To investigate the response of RGAT to metal ions, in the solvent system of DMF / H2O (1 / 99, v / v), Fe 3+ 、Fe 2+ 、Cr 3+ 、 Ag + 、 Cu 2+ 、 Al 3+ 、 Na + 、 K + 、 Mg 2+ 、Ca 2+ 、Hg 2+ 、Zn 2+ 、Co 2+ 、Cd 2+ 、Pb 2+ 、 Mn 2+ 、Ni 2+ The color, fluorescence, ultraviolet-visible spectrum and fluorescence spectrum of the solution before and after adding 17 metal ions were analyzed, and the results are as follows.

[0069] Figure 2 It is the color under visible light and the fluorescence under 365 nm ultraviolet light before and after adding metal ions to the DMF / H2O (1 / 99, v / v) solution of RGAT. It can be seen that the solution color has no obvious change and no fluorescence is exhibited.

[0070] Figure 3 It is the ultraviolet-visible absorption spectrum ( Figure 3 a in) and fluorescence spectrum ( Figure 3In b). As can be seen from the figure, none of the 17 metal ions caused obvious changes in the UV-visible spectrum and fluorescence spectrum of RGAT, indicating that in the DMF / H2O (1 / 99, v / v) system, RGAT did not show obvious response to the 17 metal ions.

[0071] Example XII Response of RGAT to Metal Ions

[0072] To investigate the response of RGAT to metal ions, Fe was added to RGAT in the CH3CN / H2O (20 / 80, v / v) solvent system. 3+ 、Fe 2+ 、Cr 3+ 、Ag + 、Cu 2+ 、Al 3+ 、Na + 、K + 、Mg 2+ 、Ca 2+ 、Hg 2+ 、Zn 2+ 、Co 2+ 、Cd 2+ 、Pb 2+ 、Mn 2+ 、Ni 2+ The colors, fluorescence, UV-visible spectra and fluorescence spectra of the solutions before and after adding 17 metal ions were analyzed, and the results are as follows.

[0073] Figure 4 Shows the color under visible light and fluorescence under 365 nm ultraviolet light before and after adding metal ions to the CH3CN / H2O (20 / 80, v / v) solution of RGAT. It can be seen that only Fe 3+ made the color of the CH3CN / H2O (20 / 80, v / v) solution of RGAT turn red and emit yellow-green fluorescence.

[0074] Figure 5 Shows the UV-visible absorption spectra ( Figure 5 in a) and fluorescence spectra ( Figure 5 in b) of the CH3CN / H2O (20 / 80, v / v) solution of RGAT before and after adding metal ions. It can be found from Figure 5 in a that Fe 3+ caused an absorption peak of RGAT at 530 nm, and the absorbance enhancement factor was 24 times, corresponding to the color observed by the naked eye, while other ions did not cause obvious changes in the UV-visible absorption spectrum of the RGAT solution. It can be found from Figure 5 in b that Fe 3+The fluorescence of RGAT at 554 nm was enhanced, and the fluorescence intensity increased by 69 times. The fluorescence spectra of the RGAT solution were not significantly changed by other ions. Therefore, in the CH3CN / H2O (20 / 80, v / v) system, the ultraviolet-visible absorption spectrum and fluorescence spectrum of RGAT were highly selective for Fe 3+ with high selectivity response.

[0075] Example XIII Relationship between the absorption spectrum and fluorescence spectrum of RGAT and Fe 3+ concentration

[0076] To explore the relationship between the absorption spectrum and fluorescence spectrum of RGAT and Fe 3+ concentration, the ultraviolet-visible absorption spectra and fluorescence spectra of RGAT in CH3CN / H2O (20 / 80, v / v) solution after adding different concentrations of Fe 3+ were investigated, as shown in Figure 6 As the concentration of Fe 3+ gradually increased, the absorbance of RGAT at about 530 nm ( Figure 6 a in) and the fluorescence intensity near 554 nm ( Figure 6 b in) both gradually increased. And in the concentration range of 0 - 50 μM of Fe 3+ , a good linear relationship was presented with the concentration of Fe 3+ . The linear equations of absorbance and fluorescence intensity were A = 0.00227×[Fe 3+ – 0.01093 and F = 16.239101×[Fe 3+ – 18.34921 respectively, and the correlation coefficients were 0.997 and 0.997 respectively. The detection limits of Fe 3+ detected by ultraviolet-visible absorption spectrum and fluorescence spectrum were 1.8×10 -6 mol / L and 2.4×10 -9 mol / L respectively.

[0077] Example XIV Anti-interference ability of RGAT for detecting Fe 3+ To investigate the anti-interference ability of RGAT for other coexisting ions when detecting Fe

[0078] in the CH3CN / H2O (20 / 80, v / v) system, Al 3+ 、Cr 3+ 、Fe 3+ 、Ag 3+ 、Cu 2+ 、Na + 、K 2+ 、Mg + 、K + 、Mg2+ , Ca 2+ , Hg 2+ , Zn 2+ , Co 2+ , Cd 2+ , Pb 2+ , Mn 2+ , Ni 2+ , one of them, compare the ultraviolet-visible absorption spectrum and fluorescence spectrum of the solution before and after adding these ions. As Figure 7 shown, after adding other interfering ions, whether it is the absorbance at 530 nm ( Figure 7 a in) or the fluorescence intensity near 554 nm ( Figure 7 b in) changes very little. Therefore, RGAT has strong anti-interference ability when detecting Fe 3+ in the CH3CN / H2O(20 / 80, v / v) system.

[0079] Example XV Detection of Fe 3+ by RGAT Time Responsiveness

[0080] In order to investigate the response speed of RGAT in the CH3CN / H2O (20 / 80, v / v) system for detecting Fe 3+ , record the ultraviolet-visible absorption and fluorescence spectra of the solution starting from the addition of Fe 3+ and at regular intervals, as Figure 8 . As can be seen from Figure 8 a in, after adding Fe 3+ , the absorbance of the RGAT solution increases significantly within 7 min and basically reaches a stable state after 8 min. As can be seen from Figure 8 b in, after adding Fe 3+ , the fluorescence intensity of the RGAT solution increases rapidly to the maximum and stabilizes within 30 min. Therefore, RGAT has the ability to quickly detect Fe 3+ in the CH3CN / H2O (20 / 80, v / v) system.

[0081] Example XVI Reversibility of Fe Detection by RGAT 3+

[0082] Add Fe 3+ to the CH3CN / H2O (20 / 80, v / v) solution of RGAT, and then add 60 µM EDTA solution to investigate the reversibility of RGAT for detecting Fe 3+ , and the results are as Figure 9 . As can be seen from Figure 9 a in: After adding Fe 3+The color of the solution changes from colorless to pink, and when EDTA solution is continuously added, the color changes back to colorless. For the solution after adding Fe to the RGAT solution 3+ absorbance analysis was performed, and an absorption peak appeared at 530 nm. When EDTA solution was continuously added, the absorbance value decreased to be close to the original absorbance value of RGAT. Therefore, the colorimetric detection of Fe by RGAT 3+ is reversible. As can be seen from Figure 9 b in: When Fe is added to the RGAT solution 3+ the solution shows yellow fluorescence, and when EDTA solution is continuously added, the fluorescence quenches. For the fluorescence intensity of the solution after adding Fe to the RGAT solution 3+ analysis was performed, and it was found that when Fe was added to the RGAT solution 3+ the fluorescence of the solution increased significantly. After continuously adding an excessive amount of EDTA solution, the fluorescence intensity at 554 nm decreased significantly and basically returned to the original fluorescence intensity of RGAT. It can be seen that the detection of Fe by RGAT 3+ is a reversible process, laying a foundation for the recycling of the probe.

[0083] Example 17 Practicality of RGAT

[0084] To investigate the practicality of RGAT, according to the conventional method, spiked analysis of pond water and tap water from the Dushu Lake Campus of Soochow University was performed using RGAT. The fluorescence emission spectra of the RGAT solution containing pond water (or tap water) and spiked Fe 3+ were measured. According to the linear relationship between the fluorescence intensity of the RGAT solution and the concentration of Fe 3+ the concentration of Fe 3+ the recovery rate and relative standard deviation of Fe 3+ were calculated. The results are shown in Table 1: The measured concentration of Fe 3+ was close to the added concentration of Fe 3+ . The recovery rate of Fe 3+ was between 96.10 - 102.45%, and the relative standard deviation of three parallel experiments was less than 1.21%. Therefore, RGAT can be used to effectively analyze Fe in actual environmental water samples 3+ .

[0085] Table 1 Determination of Fe in pond water and tap water using RGAT 3+ (n = 3)

[0086]

[0087] Solvent system: CH3CN / H2O (20 / 80, v / v), RGAT concentration: 10 µM, RSD: relative standard deviation.

[0088] Example 18 Toxicity of RGAT

[0089] Cytotoxicity assay method: In a 96-well plate, 100 μL of cell suspension (about 5000 cells / well) was inoculated into each well. The plate was pre-incubated in an incubator at 37 °C (5% CO2) for 24 h. Then, 10 μL of CCK-8 solution was added to each well of the plate, and the culture plate was incubated in the incubator for 1 h. Finally, 1 μL of the test substance RGAT with different concentrations (the solvent is CH3CN) was added to the wells. After incubating the culture plate in the incubator for 24 h, the absorbance at 450 nm was measured using a microplate reader.

[0090] Cytotoxicity assay results: The cytotoxicity of RGAT measured by the microplate reader is as Figure 10 shown. The survival rate of cells without RGAT treatment was set as 100%. The survival rates of cells treated with 20, 40, and 60 μM RGAT were 100.02%, 100.96%, and 101.35% respectively, indicating that RGAT has no negative impact on the survival rate of grass carp kidney cells (cik). Therefore, the cytotoxicity of RGAT is very low and it can be fully used for biological samples.

[0091] Example XIX Antibacterial Property of RGAT

[0092] Antibacterial property assay method: Take 16 1-mL EP tubes and number them from 1 to 16. Add 50 μL of Bacillus thuringiensis standard bacterial solution (Bio-52496) to tubes 1 - 8 respectively, and then add 50 μL of sterile water, 50 μL of DMSO solvent, 50 μL of 1.6, 1.7, 1.8, 1.9, 2.0 mg / mL RGAT antibacterial solution (the solvent is DMSO), and 50 μL of 2.0 mg / mL bleach respectively. Add 50 μL of Serratia marcescens standard bacterial solution (Bio-72774) to tubes 9 - 16 respectively, and then the operation is the same as that for tubes 1 - 8. Mix quickly and start timing immediately. When the test bacteria and the disinfectant interact for 30 min, add the sterilized neutralizer to mix and stop the reaction. After 10 min, take 50 μL of the uniformly mixed reaction solution and transfer it to the Petri dishes containing LB medium with the same number. Heat and disinfect the spreading rod on the alcohol lamp flame, then dip it into the reaction solution and spread it evenly on the LB medium. Seal it with a sealing film and place it in a biochemical incubator at 37 °C for natural growth for 24 h, and take pictures for recording.

[0093] Antibacterial property assay results: The antibacterial property of RGAT measured by the suspension quantitative killing experiment is as Figure 11 and 12 shown. Under the suitable growth environment, Bacillus thuringiensis (Gram-positive bacteria, Figure 11 in a) and Serratia marcescens (Gram-negative bacteria,Figure 12 In a), it grows and spreads all over the surface of the culture medium. The DMSO organic solvent has an impact on the growth of Bacillus thuringiensis ( Figure 11 in b) and Serratia marcescens ( Figure 12 in b) with little effect, and the surface of the culture medium is also covered, showing almost no obvious difference from the growth phenomenon under normal conditions. Analyzing the effects of different concentrations of RGAT antibacterial solution, it can be found that when the concentration of the RGAT solution is 1.6 mg / mL, Bacillus thuringiensis ( Figure 11 in c) has a small number of large white circular colonies growing on the surface of the culture medium, and Serratia marcescens ( Figure 12 in c) has a small number of white fine colonies surviving on the surface of the culture medium. In the process of gradually increasing the concentration of the RGAT solution to 2.0 mg / mL, it is observed that the antibacterial effect gradually increases with the increase in the concentration of the RGAT solution ( Figure 11 in d to g and 12 in d to g). The sterilization effect of the RGAT solution with a concentration of 1.9 mg / mL is equivalent to that of 2.0 mg / mL of bleach ( Figure 11 in h and 12 in h), and there are no colonies growing on the surfaces of the culture media of Bacillus thuringiensis ( Figure 11 in f) and Serratia marcescens ( Figure 12 in f). Therefore, RGAT has strong inhibition on the growth and reproduction of both Gram-positive and Gram-negative bacteria, and RGAT has better antibacterial performance against Gram-positive and Gram-negative bacteria than commercially available bleach.

Claims

1. A 2-aminothiazolyl rhodamine 6G derivative, whose chemical structure is as follows: 。 2. The method for preparing the 2-aminothiazolyl rhodamine 6G derivative according to claim 1, characterized in that: The method comprises the following steps: taking rhodamine 6G and 2-aminothiazole as raw materials, and preparing a 2-aminothiazolyl rhodamine 6G derivative by one-step reaction.

3. The method for preparing the 2-aminothiazolyl rhodamine 6G derivative according to claim 2, characterized in that: The reaction is carried out in an inert atmosphere; the reaction temperature is 50-100° C. and the reaction time is 2-20 hours.

4. The 2-aminothiazolyl rhodamine 6G derivative of claim 1 as Fe 3+ Application of spectral probes.

5. The 2-aminothiazolyl rhodamine 6G derivative according to claim 1 is used in the preparation of Fe 3+ Application of detection reagents.

6. Use of the 2-aminothiazolyl rhodamine 6G derivative according to claim 1 as an antibacterial agent, or use of the 2-aminothiazolyl rhodamine 6G derivative according to claim 1 in the preparation of an antibacterial agent.

7. A kind of Fe 3+ The detection method is characterized in that The method comprises the following steps: using the 2-aminothiazolyl rhodamine 6G derivative according to claim 1 to detect Fe 3+ .

8. Fe according to claim 7 3+ The detection method is characterized in that Spectral detection includes one or both of ultraviolet-visible spectral detection and fluorescence spectral detection.

9. An antibacterial method, comprising the following steps: using the 2-aminothiazolyl rhodamine 6G derivative of claim 1 for antibacterial purposes.

10. The antibacterial method according to claim 9, characterized in that: The bacteria include one or more of Gram-positive bacteria and Gram-negative bacteria.

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