A fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof

Abstract

The application discloses a kind of fluorescent probe for detecting aluminum ions in pure water and cell and preparation method thereof, the technical field of fluorescence probe, the structural formula of the fluorescent probe is: The application uses the above-mentioned fluorescent probe for detecting aluminum ions in pure water and cell and preparation method thereof, the synthesized probe molecule L has good AIE characteristics, probe molecule L can quickly identify and detect aluminum ions in the mixed solution of DMF and water, and has high selectivity and good anti-interference, with the assistance of SDS, the detection of Al 3+ From semi-aqueous phase to pure water phase change is successfully realized, Al 3+ Specific recognition can be realized in pure water, and Al 3+ Detection in tap water sample and cell can be carried out.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluorescent probe, in particular to a fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof. BACKGROUND

[0002] In recent years, the recognition of metal ions has gradually become an important branch of supramolecular chemistry, and the specific recognition and detection of metal ions are involved in various fields of production and life. Aluminum is the most abundant metal element on earth. In daily life, aluminum, as a common metal, is widely used by people and occupies an important position in industry and agriculture. However, excessive aluminum ions not only cause environmental pollution, but also harm human health and plant growth. Among them, the drinking water health standard stipulates that the maximum allowable content of aluminum is 0.20 mg / L. Excessive intake of aluminum can cause damage to the brain, heart and liver functions and immune function of the human body, and induce Alzheimer's disease. After being absorbed by the digestive system, aluminum is toxic to the activity of osteoblasts and inhibits the synthesis of bone matrix, resulting in an increase in urinary calcium excretion and a decrease in body calcium. Aluminum binds to transferrin, causing interference with the distribution and metabolism of iron in the plasma, resulting in non-iron deficiency anemia. In addition, excessive intake of aluminum can cause kidney failure, reduced gastric juice secretion and other diseases.

[0003] The detection methods of metal ions have experienced a development process from traditional analysis methods to instrumental analysis methods, and from single detection means to combination of multiple technologies. The commonly used analysis and detection methods currently include complexometric titration, spectrophotometry, chemiluminescence analysis, electrochemical analysis, chromatography, atomic spectroscopy and mass spectrometry, etc. Among them, complexometric titration and spectrophotometry are simple to operate, economical in equipment, but have large errors. Chemiluminescence analysis and electrochemical analysis have high sensitivity, wide linear range and poor selectivity. Chromatography technology is relatively advanced, and the conventional indicators are complete, but the instrument maintenance cost is high, and the detection time is relatively long. Compared with the above several analysis methods, spectral analysis methods are rich in types and excellent in performance, and are commonly used for determination of trace and trace metal elements.

[0004] At present, the commonly used spectral analysis methods can be divided into atomic spectroscopy and molecular spectroscopy. Among them, molecular spectroscopy includes ultraviolet-visible spectrophotometry, infrared spectroscopy, molecular fluorescence spectroscopy and molecular phosphorescence spectroscopy, etc. Fluorescence spectroscopy is widely developed and utilized due to its excellent sensitivity and fast response speed, and gradually becomes an important detection method in the fields of analytical chemistry, medicine, biochemistry, environmental chemistry, etc. Fluorescent probes can react with specific target analytes, causing changes in fluorescence signals, so as to achieve the purpose of detecting specific target analytes. Therefore, in recent years, fluorescent probes have received extensive attention from the scientific community and can be applied to environmental protection, intracellular fluorescence imaging and other fields.

[0005] Most of the fluorescent probes can only be applied in organic phase or semi-aqueous phase due to the aggregation-induced quenching (ACQ) effect. In order to overcome the above situation, in recent years, people have begun to try to synthesize new fluorescent probes with AIE characteristics and apply them to the detection of ions in pure water. But most of these probes are based on tetraphenyl ethylene derivatives. These molecules not only have complex synthesis routes, but also have expensive raw materials, which greatly increases the requirements and difficulties of production technology and process in the actual application process, and also increases the production cost.

[0006] The synthesis route of the Schiff base compound is simpler, the reaction material is more easily obtained, and it has better application prospect, so it has attracted more and more attention. However, like most small organic molecule fluorescent probes, due to the solubility problem, hydrolysis and the existence of ACQ effect, such probes cannot be applied in pure water. The fluorescent probes based on Schiff base structure for detecting Al 3+ in water are even fewer. It can be said that this work has certain difficulty, and it is an opportunity and challenge in the field of scientific research. SUMMARY

[0007] The purpose of the present application is to provide a fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof. The synthesized probe molecule L has good AIE characteristics, and the probe molecule L can quickly recognize and detect aluminum ions in a mixed solution of DMF and water, has high selectivity and good anti-interference property, and successfully realizes the transformation of Al 3+ detection from semi-aqueous phase to pure water phase. It can specifically recognize Al 3+ in pure water and can be used for detecting Al 3+ in cells.

[0008] To achieve the above purpose, the present application provides a fluorescent probe for detecting aluminum ions in pure water and cells, and the structure formula of the fluorescent probe is:

[0009]

[0010] The structure is characterized by:

[0011] 1HNMR (500 MHz, DMSO) δ (ppm) 13.48 (s, 1H), 9.06 (s, 1H), 8.12 (d, J = 2.4 Hz, 1H), 7.94 (d, J = 8.6 Hz, 2H), 7.89 (d, J = 8.5 Hz, 2H), 7.86 (dd, J = 8.6, 2.5 Hz, 1H), 7.38 (s, 4H), 7.11 (d, J = 8.6 Hz, 1H), 2.98 - 2.91 (m, 1H), 1.23 (d, J = 6.9 Hz, 6H). 13 CNMR (500 MHz, DMSO) δ (ppm) 162.93, 161.38, 148.19, 145.97, 144.16, 133.39, 132.08, 131.56, 129.48, 127.86, 127.19, 121.79, 120.13, 117.99, 109.79, 33.56, 24.34.

[0012] The application provides a preparation method of a fluorescent probe for detecting aluminum ions in pure water and cells, and comprises the following steps:

[0013] Step one, cyanophenol, urotropine and trifluoroacetic acid are taken into a round-bottom flask, and then extracted with dichloromethane and hydrochloric acid for multiple times after heating and refluxing in an oil bath, and then washed with water for two to four times after extraction and layer separation, and then washed with saturated brine;

[0014] Step two, the organic layer is dried with sodium sulfate, filtered, rotary evaporated and dried, and then 4-isopropyl aniline and ethanol are added as solvents to perform rotary evaporation, recrystallization and suction filtration after refluxing in an oil bath;

[0015] Step three, the product is subjected to structure characterization.

[0016] Preferably, the raw materials used in the step one are used in the following amounts: cyanophenol 0.2-1g, urotropine 1-4g and trifluoroacetic acid 30-50mL.

[0017] Preferably, the temperature of the oil bath in the step one is 75-90°C, and the refluxing time is 4-8 hours.

[0018] Preferably, the dichloromethane is used in an amount of 100-200mL, and the hydrochloric acid is used in an amount of 80-150mL with a concentration of 1mol / L.

[0019] Preferably, the solvents used in the step two are used in the following amounts: 4-isopropyl aniline 0.1-0.4g and ethanol 80-150mL.

[0020] Preferably, the temperature of the oil bath in the step two is 70-95°C, and the refluxing time is 6-10 hours.

[0021] Therefore, the application adopts the above-mentioned fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof, and has the following beneficial effects:

[0022] (1) The synthesized fluorescent probe molecule L has good AIE characteristics and can emit orange-yellow fluorescence in an aggregated state.

[0023] (2) The fluorescent probe molecule L can quickly recognize and detect aluminum ions in a mixed solution of DMF and water, and has high selectivity and good anti-interference property. The ultraviolet and fluorescence spectra of the fluorescent probe molecule L change obviously, and the color of the solution fluorescence changes from orange-yellow to green under the irradiation of an ultraviolet lamp. This phenomenon can achieve the effect of naked-eye recognition.

[0024] (3) With the aid of SDS, the detection of aluminum ions can be successfully realized from a semi-aqueous phase to a pure aqueous phase, and aluminum ions can be specifically recognized in pure water.

[0025] (4) The mechanism of the probe molecule for recognizing aluminum ions is explored by means of mass spectrometry, nuclear magnetic resonance, fluorescence spectroscopy and the like. Research shows that the probe molecule L first undergoes 2:1 chelation with Al 3+ , and then the C=N double bond in the molecular structure of the probe molecule L breaks, generating a reactant molecule 1 with AIE effect, so as to release the green fluorescence of the AIE of the molecule 1.

[0026] (5) The probe molecule can be used for detecting Al 3+ in cells.

[0027] The technical solutions of the application will be further described in detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is an ultraviolet absorption spectrum diagram and a fluorescence spectrum diagram of a probe molecule L of an embodiment of the fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof according to the application in a mixed solvent of THF / water with different proportions;

[0029] Figure 2 is a fluorescence spectrum diagram of a molecule 1 in a mixed system of THF / water with different proportions in an embodiment of the fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof according to the application;

[0030] Figure 3 is a fluorescence spectrum diagram of the probe molecule L in a mixed solution of DMF / water with 10 times the amount of different metal ions and a fluorescence intensity diagram of the probe molecule L at 506 nm in an embodiment of the fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof according to the application;

[0031] Figure 4 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a fluorescence spectrum diagram of probe molecule L in a mixed solution of SDS water after adding 10 times of different metal ions, and a fluorescence intensity diagram of probe molecule L at 506 nm;

[0032] Figure 5 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a fluorescence emission spectrum diagram of probe molecule L (50 μM) in a DMF / water (2:8, v:v) solvent after gradually adding Al 3+ (0-2 equiv);

[0033] Figure 6 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a linear relationship between the (I0-I) / I0 ratio at 552 nm and the Al 3+ concentration after gradually adding Al 3+ (0-2 equiv) to probe molecule L (50 μM) in a DMF / water solvent;

[0034] Figure 7 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a Job's plot diagram of probe molecule L in a DMF / water mixed solvent (f w = 80%);

[0035] Figure 8 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a mass spectrum diagram of probe molecule L in an organic solvent methanol and probe molecule L after adding 2 times of Al 3+ in the organic solvent methanol;

[0036] Figure 9 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, nuclear magnetic hydrogen spectrum diagrams of probe molecule L, probe molecule L+Al 3+ , and probe molecule 1;

[0037] Figure 10 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, a mechanism diagram of the reaction of probe molecule L and Al 3+ ;

[0038] Figure 11 is a fluorescence probe for detecting aluminum ions in pure water and cells and a preparation method thereof, an MTT assay for studying the influence of different concentrations of probe molecule L on the proliferation of HeLa cells;

[0039] Figure 12 This invention relates to a fluorescent probe for detecting aluminum ions in pure water and cells, and an embodiment of its preparation method, which describes the fluorescence imaging of aluminum ions in HeLa cells by probe molecule L.

[0040] Figure 13 This is the hydrogen nuclear magnetic spectrum of probe molecule L, an embodiment of the present invention, which is a fluorescent probe for detecting aluminum ions in pure water and cells and its preparation method.

[0041] Figure 14 This is the carbon NMR spectrum of probe molecule L, an embodiment of the present invention, which describes a fluorescent probe for detecting aluminum ions in pure water and cells and its preparation method. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0044] Example 1

[0045] like Figure 1 and Figure 2 As shown, this invention provides a fluorescent probe for detecting aluminum ions in pure water and cells. The structural formula of the fluorescent probe is as follows:

[0046]

[0047] The structure is characterized as follows:

[0048] 1 HNMR (500MHz, DMSO) δ (ppm) 13.48 (s, 1H), 9.06 (s, 1H), 8.12 (d, J = 2.4Hz, 1H), 7.94 (d, J = 8.6Hz, 2H), 7.89 (d, J = 8.5 Hz,2H),7.86(dd,J=8.6,2.5Hz,1H),7.38(s,4H),7.11(d,J=8.6Hz,1H),2.98–2.91(m,1H),1.23(d,J=6.9Hz,6H). 13 CNMR(500MHz,DMSO)δ(ppm)162.93,161.38,148.19,145.97,144.16,133.39,132.0 8,131.56,129.48,127.86,127.19,121.79,120.13,117.99,109.79,33.56,24.34.

[0049] The application further provides a preparation method of the fluorescent probe for detecting aluminum ions in pure water and cells, and comprises the following steps:

[0050] Step one, 0.5g cyanophenol, 2.15g urotropine and 40mL trifluoroacetic acid are taken in a round-bottom flask, and then the mixture is heated to reflux in an oil bath at 79℃ for 5 hours, and then extracted with 130mL dichloromethane and 100mL hydrochloric acid with a concentration of 1mol / L for multiple times, and then washed with water for two to four times after the extraction is separated into layers, and then washed with saturated brine;

[0051] Step two, the organic layer is dried with sodium sulfate, and then 0.21g 4-isopropylaniline and 100mL ethanol are added as solvents, and then the mixture is refluxed in an oil bath at 88℃ for 8.5 hours, and then the mixture is subjected to rotary evaporation, recrystallization and suction filtration;

[0052] Step three, the product is subjected to structure characterization.

[0053] The spectral test conditions and methods of the prepared fluorescent probe comprise:

[0054] 1. AIE property detection: the probe molecule L is prepared into samples containing different proportions of THF / water solvents, and the final concentration of the probe molecule L in the whole system is 50μM, and the luminescent properties of the molecule are tested by a fluorescence spectrometer and a UV-visible absorption spectrometer.

[0055] The probe molecule L is easily soluble in organic solvents such as THF, and is difficult to dissolve in water, therefore, the aggregation-induced fluorescence enhancement performance, namely the AIE performance, of the probe molecule L is studied by dispersing the probe molecule L in mixed systems of different proportions of THF / water. Figure 1 (a) in the figure is an ultraviolet absorption spectrum of the probe molecule L in the mixed solution of different proportions of THF / water, Figure 1 (b) in the figure is a fluorescence spectrum of the probe molecule L in the mixed solution of different proportions of THF / water.

[0056] Figure 1 In (a) in the figure, it can be observed that when the proportion of water in the mixed solution is greater than 70%, the absorption peak of the system is enhanced and an obvious tailing phenomenon appears in the long-wave region, which indicates that the probe molecule L is aggregated at this time, and compared with the ultraviolet absorption spectrum in the THF dilute solution, the ultraviolet absorption peak of the aggregated state has a slight red shift phenomenon.

[0057] Figure 1(b) in FIG. 1 shows that when the molecule is in pure THF, the probe molecule L has almost no fluorescence, but when the water content exceeds 70%, the fluorescence intensity of the probe molecule L at 546 nm suddenly increases, and with the increase of the water content, the peak is always enhanced until the water ratio reaches 95%, the fluorescence intensity of the probe molecule L in the mixed solution with a water content of 95% is increased by 11 times compared with the fluorescence intensity of the probe molecule L in pure THF, because when the water ratio is small, the C-C single bond and C-N single bond on the phenyl group of the probe molecule L can freely rotate to cause non-radiative decay and cause the molecule to emit weak fluorescence. However, in the aggregated state, due to the formation of intramolecular hydrogen bond (N…HO-), the rigidity of the molecule is increased, thereby limiting the internal rotation of the molecule, and finally making the fluorescence of the system enhanced, which shows that the probe molecule L is likely to have good AIE properties.

[0058] Some Schiff base derivatives can emit strong fluorescence in water, and people sometimes mistakenly think that this is due to the AIE phenomenon caused by the aggregation of these compounds in water. However, in fact, it is because these compounds can be hydrolyzed into corresponding aldehydes and amines in water, and the aldehydes have AIE characteristics, so they can emit fluorescence in water. That is, the salicylaldehyde Schiff base compounds can emit fluorescence in water is not their own luminescent properties, but the phenomenon brought by the aldehyde compounds with AIE produced after hydrolysis.

[0059] In order to further investigate whether the probe molecule L really has AIE characteristics, whether it will hydrolyze in water, and whether the light emitted in water is due to its own properties or related to molecule 1, the luminescent properties of molecule 1 dissolved in different proportions of THF / water mixed solution were studied.

[0060] The structural formula of molecule 1 is:

[0061]

[0062] Figure 2 (a) in FIG. 1 is the fluorescence spectrum of the probe molecule 1 in the THF / water mixed system with a proportion of 0-70%, Figure 2 (b) in FIG. 1 is the fluorescence spectrum of molecule 1 in the THF / water mixed system with a proportion of 70-99%. As Figure 2As shown, molecule 1 itself emits little fluorescence in pure THF, but when the volume of water is between 30-80%, molecule 1 emits strong green fluorescence at 506 nm. By comparison, it is found that the fluorescence at this place is completely different from the orange-yellow fluorescence emitted by product probe molecule L at 546 nm, so the fluorescence emitted by probe molecule L is unrelated to probe molecule 1 and should be caused by the AIE luminescence property of the molecule itself. This further indicates that compound L has good AIE properties and is relatively stable in water and does not hydrolyze.

[0063] 2. Ion selective detection: (1) Dissolve probe molecule L in DMF organic solvent, then add Fe 3+ , Mn 2+ , Cu 2+ , Co 2+ , K + , Ba 2+ , LI + , Na + , Al 3+ , NI + , Ca 2+ , Cr 2+ , Cd 2+ , Pb 2+ , Hg 2+ , Mg 2+ and Zn 2+ chlorides of seventeen common metal ions into the solution, keeping the concentration of the final molecule at 50 μM and the concentration of the ions at 500 μM, and the volume ratio of DMF to water at 2:8, and test the fluorescence emission spectrum and ultraviolet absorption spectrum of the solution in the presence of different metal ions by fluorescence spectrometer and ultraviolet-visible absorption spectrometer. (2) Dissolve probe molecule L in acetonitrile, the mother liquor concentration is 5 mM, add 10 mM SDS solution, then add various metal ions in method (1), keeping the concentration of the final molecule at 50 μM and the concentration of the ions at 500 μM, and test the fluorescence emission spectrum and ultraviolet absorption spectrum.

[0064] 3. Anti-interference ability detection: (1) Add different ions (final concentration 500 μM) to the DMF / water (2:8, v:v) mixed solution containing 50 μM of probe molecule L and 500 μM of aluminum ions, and detect the changes in the fluorescence emission spectrum and ultraviolet absorption spectrum of the mixed solution containing various interference ions. (2) Add different ions of the same concentration to the mixed solution of SDS containing 50 μM of probe molecule L and 500 μM of aluminum ions, and the concentration of SDS is 10 mM, and detect the fluorescence emission spectrum and ultraviolet absorption spectrum of the solution, and compare the mixed ions with Al 3+The effect of this mixed solution on the fluorescence emission spectrum allows us to examine the competing ion pairs between the probe molecules L and Al. 3+ Interference in identification.

[0065] Figure 3 (a) represents the probe molecule L in DMF / water (f w =80%, λ ex Fluorescence spectra of 10 times the amount of different metal ions added to a mixed solution (λ=310nm). Figure 3 (b) shows the fluorescence intensity of probe molecule L at 506 nm (black: probe molecule L with different metal ions added, white: probe molecule L with Al added). 3+ And ions of different metals, f w =80%, λ ex =310nm).

[0066] like Figure 3 As shown in (a), the molecule itself emits strong fluorescence in a dilute DMF / water solution due to the AIE effect, with a peak at 552 nm. However, when 10 times the amount of aluminum ions is added, the intensity of this peak weakens, and a new emission peak appears at a wavelength of 506 nm. The addition of other cations did not cause such changes in the solution.

[0067] Along with this spectral change, the change in fluorescence color is easily observed with the naked eye. Specifically, after adding aluminum ions to a solution of probe molecule L, the fluorescence of the solution changes from orange-yellow to green, achieving visual recognition of aluminum ions. This indicates that the molecule has excellent selectivity for aluminum ions.

[0068] Under the same conditions, 10 times the amount of different types of metal cations were added to solutions containing probe molecule L and aluminum ions, respectively. The fluorescence spectra are shown below. Figure 3 As shown in (b), except for Fe 3+ Other ions will not interfere with the detection of aluminum ions by the probe molecule L.

[0069] (2) Dissolve probe molecule L in acetonitrile with a mother solution concentration of 5 mM, add 10 mM SDS solution, and then add various metal ions from method (1) dropwise to keep the final molecule concentration at 50 μM and the ion concentration at 500 μM. Test its fluorescence emission spectrum and ultraviolet absorption spectrum.

[0070] To achieve the detection and identification of aluminum ions in pure water, SDS, a surfactant, was introduced into the detection system to assist the probe molecule L. Using the same method, the selectivity and anti-interference ability of probe molecule L for the detection of aluminum ions in pure water were investigated, and the results are as follows: Figure 4 As shown,Figure 4 (a) is the fluorescence spectrum of probe molecule L in DMF / water (f w = 80%, λ ex = 310 nm) with 10 times amount of different metal ions added, Figure 4 (b) is the fluorescence intensity graph of probe molecule L at 506 nm (black: probe molecule L with different metal ions added, white: probe molecule L with Al 3+ and different metal ions, f w = 80%, λ ex = 310 nm). From the results we found that the experimental phenomena in the mixed solvent of DMF / water are basically the same, that is, the recognition of probe molecule L to aluminum ions in pure water phase still has good selectivity and anti-interference.

[0071] 4. Al 3+ Titration experiment and determination of detection limit: gradually add a certain concentration of aluminum ion solution in the DMF / water (2:8, v:v) mixed solution containing 50 μM of probe molecule L, and investigate its linear response range and response sensitivity by detecting its corresponding fluorescence spectrum and UV-visible absorption spectrum changes. The detection limit is calculated by the formula DL=3σ / K, where σ is the standard deviation of the blank sample, and K is the slope of the corrected straight line. The detection of aluminum ions in a certain range (0-65 μM) can achieve quantitative analysis, and the detection limit is 0.049 μM.

[0072] As Figure 5 shown, dissolve probe molecule L (50 μM) in DMF / water (2:8, v:v) mixed solvent, when the concentration of Al 3+ is in the range of 0-100 μM, with the addition of Al 3+ , the fluorescence intensity of probe molecule L solution at 506 nm gradually increases, while the peak at 552 nm gradually weakens, when the amount of Al 3+ added reaches 70 μM, the fluorescence of the solution is the strongest, then with the concentration of Al 3+ exceeding 70 μM, the fluorescence of the solution gradually weakens. Accompanying the change of fluorescence spectrum, under the irradiation of portable ultraviolet lamp, the color of the solution can be observed by naked eye from orange yellow to green.

[0073] As Figure 6 shown, within a relatively wide range of Al 3+ concentration (0-65 μM), the (I0-I) / I0 of probe molecule L and the concentration of aluminum ions shows a good linear relationship. This shows that probe molecule L can realize quantitative detection of Al 3+ in a larger range, in addition, according to the calculation, the detection limit of probe molecule L to Al 3+The detection limit is 4.9 × 10⁻⁶. -8 M, this detection limit is significantly lower than the World Health Organization standard (7.41 μM), the acceptable level of aluminum ions in drinking water (1.85 μM), and previously reported Al. 3+ Probe. The above results indicate that the probe molecule L is effective for Al. 3+ The detection of this molecule has high sensitivity, which shows that it can meet the needs of more detection conditions.

[0074] 5. Job's plot: Plotting the probe molecule L against Al 3+ Different ratios of DMF / water (1:9, v:v) were added to a mixed solution, maintaining a total concentration of 20 μM. The intensity of the fluorescence and UV spectra changed with the ratio, and the relationship between the probe molecules L and Al was determined by plotting the results. 3+ The proportions.

[0075] like Figure 7 As shown, the probe molecules L and Al are studied using Job's plot curves. 3+ The stoichiometry of the combination was analyzed. The figure shows a coordination ratio of 2:1 between the probe molecule L and the aluminum ion. To further confirm the existence of this complex, mass spectrometry was used to investigate it. Figure 8 Image (a) shows the mass spectrum of probe molecule L in the organic solvent methanol. Figure 8 In (b), the probe molecule L is added to the organic solvent methanol with twice the amount of Al. 3+ Mass spectrum, however from Figure 8 No probe molecules L and Al were found in (b) of the sample. 3+ The peaks of the complex were found, but peaks were also found for molecule 1 and isopropylamine, indicating that probe molecule L interacts with Al. 3 + After the combination, other reactions may continue to occur.

[0076] like Figure 9 As shown, when excess Al is added to probe molecule L 3+ After (double the amount), its proton peak of imine (-HC=N-) at 9.06 ppm (H a The concentration of H+ decreased, and the proton peak of the hydroxyl group (-OH) decreased at 13.48 ppm. b The peak disappeared. Simultaneously, a proton peak (H) of the aldehyde group (-CHO) in molecule 1 appeared at 10.32 ppm. c’ Additionally, two peaks (H) were observed at 1.24 ppm and 2.94 ppm. f H e) also belong to the methyl (-CH3) and methine (-CH) in the structure of isopropyl aniline, respectively. This indicates that aluminum ions do indeed initiate the hydrolysis of the probe molecule L, making the carbon-nitrogen double bond of L break, generating molecules 1 and 4-isopropyl aniline. Therefore, the reaction mechanism of the probe molecule L and aluminum ions can be divided into two steps: the probe molecule L and aluminum ions coordinate in a 2:1 ratio, and then a decomposition reaction occurs, generating the probe molecule 1 and 4-isopropyl aniline, as shown in Figure 10 .

[0077] In order to improve the portability of the probe molecule L for detecting aluminum ions, the fluorescent probe was made into a test paper, and the performance of the test paper for detecting aluminum ions was studied. First, the test paper loaded with the probe molecule L was immersed in an SDS solution containing different concentrations of aluminum ions. After 10 minutes, it was placed under a 365 nm portable ultraviolet lamp for irradiation. It was found that the filter paper containing aluminum ions presented green fluorescence, and the green fluorescence on the filter paper gradually increased with the increase of the concentration of aluminum ions. Therefore, using this simple and low-cost material, the "naked eye" detection of the content of aluminum ions in an aqueous solution can be conveniently and quickly realized.

[0078] The tap water in the laboratory was used as a research sample, and different concentrations of aluminum ions were added to it, and its fluorescence spectrum was monitored. The data obtained was brought into the previously determined aluminum ion titration curve, and it was found that the measured results were basically consistent with the actual concentration added to the tap water sample, the recovery was good, and the standard deviation was small. This experimental result shows that the probe molecule L has good practical application value in the detection of aluminum ions.

[0079] Table 1 Determination of the content of aluminum ions in tap water by the probe molecule L

[0080]

[0081] Note: λ ex = 310 nm, DMF / water = 2:8.

[0082] Then the probe molecule L was applied to imaging, and the cytotoxicity experiment of the probe molecule L molecule was studied. As shown in Figure 11 , even when the concentration of the probe molecule L reached 100 μM, the activity of the cells was still more than 90%. The results show that the probe molecule L has good biocompatibility and does not produce obvious toxicity to living cells for a long time, which lays a foundation for the subsequent cell imaging experiment.

[0083] As shown in Figure 12 , through fluorescence microscopy observation, it was found that the probe molecule L itself presented red fluorescence in HeLa cells. But in the presence of Al 3+The fluorescence is green when the probe molecule L is present. The above research results show that the probe molecule L can be applied to the field of monitoring Al 3+ in cells.

[0084] Therefore, the present application adopts the above-mentioned fluorescent probe for detecting aluminum ions in pure water and cells and a preparation method thereof. The synthesized probe molecule L has good AIE characteristics. The probe molecule L can quickly identify and detect aluminum ions in a mixed solution of DMF and water, has high selectivity and good anti-interference performance, successfully realizes the transition of Al 3+ detection from a semi-aqueous phase to a pure aqueous phase, can specifically identify Al 3+ in pure water, and can be used for detecting Al 3+ in tap water samples and cells.

[0085] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A fluorescent probe for detecting aluminum ions in pure water and cells, characterized in that: The structural formula of the fluorescent probe is: The structure is characterized as follows: 1 HNMR(500MHz,DMSO)δ(ppm)13.48(s,1H),9.06(s,1H),8.12(d,J=2.4Hz,1H),7.94(d,J=8.6Hz,2H),7.89(d,J=8.5Hz,2H),7.86(dd,J=8.6,2.5Hz,1H),7.38(s,4H),7.11(d,J=8.6Hz,1H),2.98–2.91(m,1H),1.23(d,J=6.9Hz,6H). 13 CNMR(500MHz,DMSO)δ(ppm)162.93,161.38,148.19,145.97,144.16,133.39,132.08,131.56,129.48,127.86,127.19,121.79,120.13,117.99,109.79,33.56,24.34。 2. A method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells as described in claim 1, characterized in that: Includes the following steps: Step 1: Take cyanobenol, hexamethylenetetramine and trifluoroacetic acid in a round-bottom flask, heat and reflux in an oil bath, and then extract with dichloromethane and hydrochloric acid multiple times. After the extraction is separated into layers, wash with water two to four times, and then wash with saturated saline. Step 2: Dry the organic layer with sodium sulfate, filter, rotary evaporate, and dry again. Then add 4-isopropylaniline and ethanol as solvents, reflux in an oil bath, and perform rotary evaporation, recrystallization, and vacuum filtration. Step 3: Characterize the structure of the product.

3. The method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells according to claim 2, characterized in that: The amounts of raw materials used in step one are: 0.2-1g of cyanobiphenyl, 1-4g of hexamethylenetetramine, and 30-50mL of trichloroacetic acid.

4. The method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells according to claim 2, characterized in that: In step one, the temperature of the oil bath is 75-90℃, and the reflux time is 4-8 hours.

5. The method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells according to claim 2, characterized in that: In step one, the amount of dichloromethane used is 100-200 mL, the amount of hydrochloric acid used is 80-150 mL, and the concentration is 1 mol / L.

6. The method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells according to claim 2, characterized in that: The amount of solvent used in step two is: 0.1-0.4g of 4-isopropylaniline and 80-150mL of ethanol.

7. The method for preparing a fluorescent probe for detecting aluminum ions in pure water and cells according to claim 2, characterized in that: In step two, the temperature of the oil bath is 70-95℃, and the reflux time is 6-10 hours.

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