Application of salicylaldehyde Schiff base fluorescent probe in detection of aluminum ions

Abstract

The invention provides application of a salicylaldehyde Schiff base fluorescent probe in detection of aluminum ions, and the salicylaldehyde Schiff base fluorescent probe shows stable fluorescence emission characteristics in a liquid state and has the advantages of high response speed, high selectivity and high sensitivity to the aluminum ions. The salicylaldehyde Schiff base fluorescent probe has the advantages that the detection process of the salicylaldehyde Schiff base fluorescent probe on the aluminum ions is fast, a large-scale detection instrument is not needed, and the salicylaldehyde Schiff base fluorescent probe belongs to a Turn-on type probe, is applied to fast visual detection of Al < 3 + > in an actual water sample and a soil sample, and has important application value in the field of monitoring of the aluminum ions in the environment. In addition, the fluorescent probe can be prepared into a portable test strip through a simple process, and rapid, high-sensitivity and visual Al < 3 + > detection is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal ion detection, and particularly relates to the application of a salicylaldehyde Schiff base fluorescent probe in the detection of aluminum ions. Background Art

[0002] Al 3+ is a human nerve agent. Long-term ingestion of excessive amounts of Al 3+ can lead to serious diseases. In addition, high concentrations of Al 3+ deposition can cause soil acidification, which will seriously harm crops and the soil ecosystem. Therefore, developing a method for selectively and effectively detecting Al 3+ is extremely important for human health and ecological protection.

[0003] Traditional detection and analysis methods for Al 3+ mainly include techniques such as inductively coupled plasma optical emission spectrometry (ICP OES), atomic absorption spectrometry (AAS), and capillary electrophoresis (CE), which can precisely determine the content of Al 3+ However, these detection techniques still have many disadvantages, such as complex processes, high detection costs, the need for professional personnel, and the need for a large amount of sample pretreatment.

[0004] In recent years, fluorescence probe detection technology has become an effective method for detecting Al 3+ due to its simple operation, good selectivity, and real-time detection, which has attracted extensive attention from scientific researchers. However, due to the strong hydration ability of Al 3+ compared with transition metal ions, the coordination ability of Al 3+ is relatively poor, and it lacks spectral characteristics. Therefore, it is necessary to develop a fluorescence probe for detecting Al 3+ Summary of the Invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide the application of a salicylaldehyde Schiff base fluorescent probe in the detection of aluminum ions. The second purpose of the present invention is to provide a method for detecting aluminum ions. The third purpose of the present invention is to provide a test paper for detecting aluminum ions. The fourth purpose of the present invention is to provide a method for detecting aluminum ions using the test paper. The fifth purpose of the present invention is to provide a method for detecting aluminum ions in soil.

[0006] Considering the hard and soft acid-base theory (HSAB), Al 3+ is a hard acid and tends to bind with coordination molecules with donor atoms such as N and O to form stable complexes. Therefore, most reported Al 3+ ​Probes all contain hard-base donor sites such as N atoms and O atoms. Among them, Schiff base compounds have advantages such as simple synthesis routes, strong metal ion coordination abilities, and fast response speeds. Based on this, the present invention designed three fluorescent probes containing benzimidazole groups, benzothiazole groups, and pyridine groups respectively. The test results show that the above fluorescent probes can all selectively detect Al 3+ , and have low detection limits and fast detection speeds, and can be used as novel Schiff base fluorescent probes in the detection of Al 3+ field with broad application prospects.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides an application of a salicylaldehyde Schiff base fluorescent probe in the detection of aluminum ions. The compound structural formula of the salicylaldehyde Schiff base fluorescent probe is shown in Formula A:

[0009]

[0010] Among them, Ar is a benzimidazolyl group, a benzothiazolyl group, or 2-aminopyridine.

[0011] Preferably, the compound structural formula of the salicylaldehyde Schiff base fluorescent probe is shown in Formula 3a, Formula 3b, and Formula 3c:

[0012]

[0013] Preferably, the salicylaldehyde Schiff base fluorescent probe is prepared by a preparation method including the following steps:

[0014] The heterocyclic amino compound reacts with 5-methylsalicylaldehyde to obtain the salicylaldehyde Schiff base fluorescent probe; the heterocyclic amino compound is selected from 2-aminobenzimidazole, 2-aminobenzothiazole, or 2-aminopyridine.

[0015] Based on 2-aminobenzimidazole, 2-aminobenzothiazole, 2-aminopyridine which are low-cost and easy to obtain and 5-methylsalicylaldehyde as raw materials, the present invention quickly, efficiently, and greenly synthesized three Schiff base fluorescent probes through a simple one-step Schiff base condensation reaction. This method avoids the high cost, complex steps, and harsh conditions of traditional synthesis, uses cheap and easily available raw materials, and does not require expensive catalysts or special drugs and equipment. The reaction conditions of the preparation method of the fluorescent probe of the present invention are easy to control, the product purification is simple, and the yield is as high as 90%.

[0016] More preferably, when the heterocyclic amino compound is selected from 2-aminobenzimidazole, the reaction is carried out in an alcohol solvent.

[0017] More preferably, when the heterocyclic amino compound is selected from 2-aminobenzimidazole, the reaction temperature of the reaction is 75 to 95 °C; the reaction time is 2 to 4 h.

[0018] More preferably, when the heterocyclic amino compound is selected from 2-aminobenzothiazole, the reaction is carried out in an aromatic hydrocarbon solvent.

[0019] More preferably, when the heterocyclic amino compound is selected from 2-aminobenzothiazole, the reaction temperature of the reaction is 100 to 120 °C; the reaction time is 2 to 4 h.

[0020] More preferably, when the heterocyclic amino compound is selected from 2-aminopyridine, the reaction is carried out in an alcohol solvent.

[0021] More preferably, when the heterocyclic amino compound is selected from 2-aminopyridine, the reaction temperature of the reaction is 70 to 90 °C; the reaction time is 0.5 to 3 h.

[0022] Preferably, the solution system for the salicylaldehyde Schiff base fluorescent probe to detect aluminum ions is N,N-dimethylformamide (DMF)-aqueous solution or pure DMF.

[0023] The second aspect of the present invention provides a method for detecting aluminum ions, comprising the following steps: preparing a probe solution with the salicylaldehyde Schiff base fluorescent probe described in the first aspect, the solvent of the detection system being DMF-aqueous solution or pure DMF, adding the solution to be detected, and if the detection system emits yellow-green fluorescence, the presence of aluminum ions is detected;

[0024] Alternatively, using a fluorescence spectroscopy detection method, when detecting, 405 nm fluorescence is used as the excitation light, and fluorescence data is obtained by monitoring and detecting fluorescence changes. If the fluorescence intensity of the fluorescence emission peak of the fluorescent probe increases, the presence of aluminum ions is detected.

[0025] Preferably, it specifically comprises the following steps: monitoring and detecting the fluorescence change range with a wavelength of 400 - 750 nm to obtain fluorescence data. If the fluorescence intensity of the fluorescence emission peak of the fluorescent probe at 508 - 510 nm increases, the presence of aluminum ions is detected.

[0026] Preferably, the volume ratio of DMF to water in the DMF-aqueous solution is (7 - 11):1.

[0027] More preferably, the volume ratio of DMF to water in the DMF-aqueous solution is (8 - 10):1.

[0028] Preferably, the solution to be detected is added to the probe solution in the form of a DMF solution to be detected.

[0029] Preferably, the concentration of the salicylaldehyde Schiff base fluorescent probe in the probe solution is 1-1000 μmol / L.

[0030] More preferably, the concentration of the salicylaldehyde Schiff base fluorescent probe in the probe solution is 1-100 μmol / L.

[0031] Even more preferably, the concentration of the salicylaldehyde Schiff base fluorescent probe in the probe solution is 5-50 μmol / L.

[0032] Preferably, the process of the fluorescence change includes: the fluorescence intensity of the probe solution increases to the maximum value within 100 s.

[0033] The third aspect of the present invention provides a test paper for detecting aluminum ions, and the test paper is a test paper or filter paper loaded with the salicylaldehyde Schiff base fluorescent probe described in the first aspect.

[0034] Preferably, the test paper for detecting aluminum ions is prepared by the following method: the salicylaldehyde Schiff base fluorescent probe described in the first aspect is formulated into a solution with DMF-aqueous solution or pure DMF, the test paper or filter paper is immersed in the solution, and after immersion, it is taken out and dried to obtain the test paper for detecting aluminum ions.

[0035] More preferably, the concentration of the solution is 10 -4 ~10 -1 mol / L.

[0036] More preferably, the immersion time is 5-30 min.

[0037] The fourth aspect of the present invention provides a method for detecting aluminum ions using a test paper, including the following steps: dropping the solution to be detected on the test paper described in the third aspect, and then observing the test paper under an ultraviolet lamp. If blue fluorescence appears on the test paper, the presence of aluminum ions is detected.

[0038] Preferably, the wavelength of the ultraviolet lamp is 365 nm.

[0039] Preferably, the concentration of aluminum ions in the solution to be detected is 10 -2 -10 -6 mol / L.

[0040] The fifth aspect of the present invention provides a method for detecting aluminum ions in soil, including the following steps: immersing the soil sample to be detected in DMF-aqueous solution or pure DMF, filtering to obtain the solution to be detected, and then detecting the solution to be detected using the method for detecting aluminum ions described in the second aspect.

[0041] The beneficial effects of the present invention are:

[0042] The present invention provides an application of a salicylaldehyde Schiff base fluorescent probe in the detection of aluminum ions. The salicylaldehyde Schiff base fluorescent probe exhibits stable fluorescence emission characteristics in a liquid state and has the advantages of fast response speed, high selectivity, and high sensitivity to aluminum ions. The detection process of aluminum ions using the salicylaldehyde Schiff base fluorescent probe of the present invention is fast and does not require large-scale detection instruments. It belongs to a "Turn-on" type probe and is applied to the rapid visual detection of Al 3+ in actual water samples and soil samples, and will have important application value in the field of monitoring aluminum ions in the environment. In addition, the fluorescent probe can be made into a portable test strip through a simple process to achieve rapid, highly sensitive, and visual detection of Al 3+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is the X-ray single crystal diffraction pattern of the fluorescent probe 3a;

[0044] Figure 2 is the fluorescence emission spectrum of the fluorescent probe 3a for detecting different metal ions. The inset shows the color change before and after adding Al 3+ to the probe solution;

[0045] Figure 3 is the fluorescence emission spectrum of the fluorescent probe 3b for detecting different metal ions. The inset shows the color change before and after adding Al 3+ to the probe solution;

[0046] Figure 4 is the fluorescence emission spectrum of the fluorescent probe 3c for detecting different metal ions. The inset shows the color change before and after adding Al 3、 and Zn 2+ to the probe solution;

[0047] Figure 5 is the result of the change in fluorescence intensity of the fluorescent probe 3a for detecting different metal ions;

[0048] Figure 6 is the fluorescence intensity-time curve graph of the fluorescent probes 3a, 3b, and 3c for detecting aluminum metal ions;

[0049] Figure 7 is the color change graph of the test strips loaded with the fluorescent probes 3a, 3b, and 3c for detecting Al 3+ ;

[0050] Figure 8 is the relationship between the maximum fluorescence intensity of the fluorescent probe 3a in different water samples and soil samples and different Al 3+ concentrations. DETAILED DESCRIPTION OF THE INVENTION

[0051] The content of the present invention will be further described in detail through specific embodiments below. The raw materials used in the following embodiments can be obtained from conventional commercial channels or prepared and separated by simple synthesis, unless otherwise specified; the processes used, unless otherwise specified, are all conventional processes in the art.

[0052] Example 1

[0053] Example 1 provides a fluorescent probe 3a and its synthesis method. The synthesis equation and synthesis method are as follows:

[0054]

[0055] Weigh 266.1 mg of 2-aminobenzimidazole 1a and 272.1 mg of 5-methylsalicylaldehyde 2, add them to a reaction flask, add 10 mL of absolute ethanol, and react at 85 °C for 3 h. Stop the reaction, cool to room temperature, then let it stand, and a solid will precipitate. Filter by suction, wash with absolute ethanol to obtain a crude solid, and recrystallize with absolute ethanol to obtain a pure product, denoted as fluorescent probe 3a. Fluorescent probe 3a is a yellow solid, with a yield of 91%, and the melting point test result is m.p. = 235.0 - 235.5 °C.

[0056] The structural formula and related characterization data of fluorescent probe 3a are as follows:

[0057]

[0058] 1 H NMR(600MHz,DMSO-d 6 ),δ,ppm:2.29(s,3H,CH 3 -15),6.93(d,1H,J=8.4Hz,ArH-13),7.16 - 7.23(m,2H,ArH-3,4),7.30(d,J=8.4Hz,1H,ArH-12),7.46(d,J=8.4Hz,1H,ArH-2),7.60(d,J=8.4Hz,1H,ArH-5),7.66(s,1H,ArH-10),9.60(s,1H,CH-8),11.84(s,1H,OH),12.73(s,1H,NH);

[0059] 13 C NMR(150MHz,DMSO-d 6), δ, ppm: 19.92 (C-15), 111.22 (C-2), 116.74 (C-13), 118.60 (C-9), 119.09 (C-5), 121.94 (C-3), 122.26 (C-4), 128.28 (C-11), 131.80 (C-10), 134.02 (C-12), 135.54 (C-1), 142.36 (C-6), 154.06 (C-14), 158.45 (C-7), 165.25 (C-8);

[0060] ESI-MS, m / z (%): Calcd for C 15 H 14 N 3 O ([M+H] + ): 252.1131 (100), Found: 252.1126.

[0061] The X-ray single crystal diffraction pattern of the fluorescent probe 3a is shown in the appendix Figure 1 as follows.

[0062] Example 2

[0063] Example 2 provides a fluorescent probe 3b and its synthesis method. The synthesis equation and synthesis method are as follows:

[0064]

[0065] Weigh 300.1 mg of 2-aminothiazole 1b and 272.1 mg of 5-methylsalicylaldehyde 2, add them to a reaction flask, add 5 mL of toluene, then add 30 μL of piperidine, and react at 110 °C for 3 h. Stop the reaction. After cooling to room temperature, add petroleum ether, and a solid precipitates. Filter by suction, wash with absolute ethanol to obtain a crude solid product, and recrystallize with absolute ethanol to obtain a pure product, denoted as fluorescent probe 3b. Fluorescent probe 3b is a yellow solid with a yield of 85%, and the melting point test result is m.p. = 131.0 - 132.4 °C.

[0066] The structural formula and related characterization data of the fluorescent probe 3b are as follows:

[0067]

[0068] 1 H NMR (600 MHz, DMSO-d 6 ), δ, ppm: 2.28 (s, 3H, CH 3-15), 6.94 (d, J = 8.4 Hz, 1H, ArH-13), 7.33 (d, J = 8.4 Hz, 1H, ArH-12), 7.40 - 7.45 (m, 1H, ArH-3), 7.50 - 7.55 (m, 1H, ArH-4), 7.73 (s, 1H, ArH-10), 7.94 (d, J = 8.4 Hz, 1H, ArH-2), 8.07 (d, J = 8.4 Hz, 1H, ArH-5), 9.39 (s, 1H, ArH-8), 11.24 (s, 1H, OH);

[0069] 13 C NMR (150 MHz, DMSO-d 6 ), δ, ppm: 19.90 (C-15), 116.86 (C-13), 119.31 (C-9), 122.39 (C-5), 122.56 (C-2), 125.24 (C-4), 126.70 (C-3), 128.54 (C-1), 130.41 (C-10), 133.94 (C-11), 136.59 (C-12), 151.25 (C-6), 158.57 (C-14), 165.53 (C-8), 170.62 (C-7).

[0070] The results of 1H NMR and 13C NMR both indicate that the molecular structure of compound 3b is consistent with its expectation.

[0071] Example 3

[0072] Example 3 provides a fluorescent probe 3c and its synthesis method. The synthesis equation and method are as follows:

[0073]

[0074] Weigh 188.1 mg of 2-aminobenzopyridine 1c and 272.1 mg of 5-methylsalicylaldehyde 2, add them to a reaction flask, add 10 mL of absolute ethanol, and react at 80 °C for 1 h. Stop the reaction, cool to room temperature, then let it stand, and a solid will precipitate. Filter by suction, wash with absolute ethanol to obtain a crude solid, and further recrystallize with absolute ethanol to obtain the pure product 3c, denoted as fluorescent probe 3c. Fluorescent probe 3c is an orange solid with a yield of 82%, and the melting point test result is m.p. = 116.5 - 117.9 °C.

[0075] The structural formula and related characterization data of fluorescent probe 3c are as follows:

[0076]

[0077] 11H NMR (600 MHz, DMSO-d 6 ), δ, ppm: 2.28 (s, 3H, CH 3 -13), 6.90 (d, J = 8.4 Hz, 1H, ArH-10), 7.27 (d, J = 8.4 Hz, 1H, ArH-9), 7.33 - 7.39 (m, 1H, ArH-3), 7.44 (d, J = 7.8 Hz, 1H, ArH-1), 7.57 (s, 1H, ArH-7), 7.89 - 7.95 (m, 1H, ArH-2), 8.53 (d, J = 6.0 Hz, 1H, ArH-4), 9.43 (s, 1H, CH-5), 12.73 (s, 1H, OH);

[0078] 13 13C NMR (150 MHz, DMSO-d 6 ), δ, ppm: 19.91 (C-12), 116.58 (C-10), 118.71 (C-6), 119.69 (C-1), 122.84 (C-3), 127.96 (C-7), 132.80 (C-8), 134.91 (C-9), 139.01 (C-2), 149.00 (C-4), 157.69 (C-13), 158.69 (C-11), 164.26 (C-5).

[0079] The results of 1H NMR and 13C NMR both indicate that the molecular structure of compound 3c is consistent with its expectation.

[0080] Experimental Analysis

[0081] 1. Liquid Sensing Performance of Fluorescent Probes 3a - 3c

[0082] (1) Experimental Method

[0083] Prepare three groups of 1 mL of 17 10 μM solvent systems of DMF / H 2 2O (v / v = 9:1) aqueous solutions of fluorescent probes 3a - 3c in DMF;

[0084] Prepare 5 mL of a 10 -2 M metal ion stock solution (Al 3+ , K + , Na + , Mg 2+ , Ca 2+ , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Cr 3+ , Hg 2+ , Cd2+ , Ni 2+ , Pb 2+ , Fe 2+ and Fe 3+ ions, DMF / H 2 O (v / v = 9:1)).

[0085] One solution from each of the three groups was left as a blank control group, and then 10 μL of a metal ion mother liquor with a concentration of 10 -2 M (at this time, the concentration of metal ions in the solution to be tested was 100 μM) was added to the 16 solutions in each of the three groups. After shaking for a few seconds, the test was then carried out.

[0086] A fluorescence spectrometer was selected to obtain fluorescence data in the wavelength range of λ ex = 405 nm (slit width set to 5 nm), 450 - 750 nm, and the fluorescence emission spectra of the 17 solutions in the three groups were tested respectively.

[0087] (2) Experimental results

[0088] From Figure 2 and Figure 3 it can be found that the aqueous solutions of the fluorescence probes 3a and 3b had weak fluorescence. When K + , Na + , Mg 2+ , Ca 2+ , Zn 2+ , Cu 2+ , Mn 2+ , Co 2+ , Cr 3+ , Hg 2+ , Cd 2+ , Ni 2+ , Pb 2+ , Fe 2+ and Fe 3+ were added, there was no obvious change in the solution fluorescence, and the fluorescence response could be ignored. However, when Al 3+ ions were added, the fluorescence intensity of the fluorescence emission peak of the fluorescence probe 3a at 508 nm increased, changing from weak light red fluorescence to strong yellow-green fluorescence; the fluorescence intensity of the fluorescence probe 3b at 509 nm increased, changing from weak light red fluorescence to strong yellow-green fluorescence. This indicates that the fluorescence probes 3a and 3b have high selectivity for Al 3+ and can be used as a specific "turn-on" probe for Al 3+ .

[0089] From Figure 4 it can be seen that when Al 3+ and Zn 2+The fluorescence emission peak will be enhanced. 3+ The solution changes from light purple fluorescence to yellow-green fluorescence; adding Zn 2+ The solution turned into yellow fluorescence, and the fluorescence enhancement was more significant. In addition, the fluorescence response of compound 3c to other metal ions was almost negligible, which indicated that compound 3c could be used as a fluorescent dye for Al 3+ and Zn 2+ specific “on” probe.

[0090] 2. Study on the anti-interference of fluorescent probe 3a

[0091] (1) Experimental methods

[0092] Prepare 16 sets of 10 μM solvent system: DMF / H 2 O (v / v = 9:1) DMF aqueous solution of fluorescent probe 3a;

[0093] To the prepared 16 groups of solutions (1 mL), 15 μL (15 equiv.) of other metal ions (K + 、Na + Mg 2+ , Ca 2+ 、Zn 2+ , Cu 2+ , Mn 2+ 、Co 2+ Cr 3+ , Hg 2+ 、Cd 2+ 、Ni 2+ , Pb 2+ , Fe 2+ and Fe 3+ ions) stock solution and 15 μL (15 equiv.) Al 3+ The ion mother solution is reserved;

[0094] (2) Experimental results

[0095] from Figure 5 It can be seen that the addition of Al into the fluorescent probe 3a 3+ When other metal ions are added, the fluorescence intensity of the solution does not change much. 3+ After that, the fluorescence increased. These indicate that most metal ions are not conducive to the detection of Al by fluorescent probe 3a. 3+ No noticeable interference.

[0096] 3. Fluorescent probes 3a, 3b, and 3c for Al 3+ Response time

[0097] (1) Experimental methods

[0098] Prepare a 10 μM solvent system of 1 group as DMF / H 2 O (v / v = 9:1) aqueous DMF solution of fluorescent probe 3a;

[0099] Add this solution to a quartz cuvette, place it in a fluorescence spectrometer, and quickly add 10 μL (10.0 equiv.) of Al 3+ stock solution, and record the relationship between the maximum intensity and time.

[0100] (2) Experimental results

[0101] From Figure 6 it can be found that when Al 3+ solution is quickly added to the solution of fluorescent probe 3a, the fluorescence intensity immediately increases. The reaction time between compound 3a and Al 3+ is 90 s, and the fluorescence intensity remains almost unchanged after 100 s.

[0102] Similarly, prepare 2 groups of 10 μM aqueous solutions of fluorescent probes 3b and 3c in the same way, and record the relationship between the maximum intensity and time (as Figure 6 ).

[0103] From Figure 6 it can be seen that after adding Al 3+ to the compound solution, the fluorescence intensity immediately increases and remains almost unchanged after 100 s; moreover, the reaction times of compounds 3b and 3c with Al 3+ are both 80 s, which is slightly faster than that of compound 3a (90 s).

[0104] In summary, the rapid response of compounds 3a, 3b, and 3c to Al 3+ indicates that these three fluorescent probes are all promising to be used as real-time sensors for detecting Al 3+ .

[0105] 4. Detection application of test strips loaded with compounds 3a, 3b, and 3c for Al 3+

[0106] (1) Experimental method

[0107] Cut three groups of 6 blank filter paper strips of the same size for later use;

[0108] Prepare 10 mL solutions of compounds 3a, 3b, and 3c (DMF, 10 -3 M) respectively;

[0109] Soak the three groups of filter paper strips in compounds 3a, 3b, and 3c (DMF, 10 -3M) in the solution for 10 minutes, taken out and dried to complete the preparation of the portable test strip. Observe the fluorescence color of the portable test strip under the ultraviolet lamp at 365 nm. The test strip of compound 3a is orange-red, the test strip of compound 3b is yellow, and the test strip of compound 3c is light yellow;

[0110] Dropwise add different concentrations of Al 3+ solution (10 -2 -10 -6 M) on the filter paper strips of 5 fluorescent materials in each group. After drying with a hair dryer, the results can be observed under the ultraviolet lamp at 365 nm.

[0111] (2) Experimental results

[0112] As Figure 7 shown, after dropping the Al 3+ solution, the fluorescence of the test strip changes significantly, turning from their respective colors to blue, and with the increase of the Al 3+ concentration, the fluorescence of the test paper changes from blue to blue-green fluorescence. Therefore, compounds 3a, 3b, and 3c can be made into test papers. The test strips of compounds 3a - 3c can be used to detect different concentrations of aluminum ions and have different fluorescence responses, which is convenient for visually detecting Al 3+ .

[0113] 5. Detection of Al 3+ by compound 3a in actual water samples and soil samples

[0114] Taking three actual water samples of distilled water, tap water, and river water (Pearl River water) and soil samples as the research objects, the fluorescence emission spectra of the samples were tested by the standard addition method, and the content of Al 3+ was calculated by fluorescence analysis. 3+ content.

[0115] Collect 5 mL of relevant water samples (distilled water, tap water, river water), filter them with a microporous filter membrane, and use the actual water samples to replace distilled water to prepare a DMF aqueous solution of the fluorescent probe 3a with a 10 μM solvent system of DMF / H 2 O (v / v = 9:1). Then, by the standard addition recovery method, 1 μL, 2 μL, and 4 μL of the Al 3+ stock solution (the stock solution was also prepared with distilled water, tap water, and river water) were added respectively to prepare detection solutions with different concentrations of Al 3+ (10 μM, 20 μM, 40 μM). Then fluorescence determination was carried out. Record the spectral signals at 405 nm, measure each water sample 3 times, and calculate the recovery rate according to the linear equation.

[0116] In addition, soil samples were taken from the flower pots in the laboratory. After being crushed, sieved, and dried, three 0.1 g soil samples were weighed respectively. Then, the soil samples were soaked in 2 mL of Al 3+ (10 μM, 20 μM, 40 μM) solutions (the solvent system was DMF / H 2 O (v / v = 9:1)) and placed at room temperature for 5 h. Through centrifugation and filtration through a microporous membrane, Al 3+ solutions with different concentrations after treatment were obtained. Take 1 mL of the above-mentioned aluminum ion solutions with different concentrations, add 10 μL of the mother liquor of compound 3a to them, and perform fluorescence emission spectrum tests ( Figure 8 ) and fluorescence analysis calculations (Table 1).

[0117] As can be seen from Figure 8 , by adding Al with different concentrations (10 μM, 20 μM, 40 μM) to different samples, 3+ the fluorescence intensity of compound 3a gradually increases with the increase of the Al 3+ concentration.

[0118] Through three parallel tests, the recovery rate and relative standard deviation (RSD) were determined to characterize the detection effect of the fluorescence probe 3a. The results of relevant tests and calculations are summarized in Table 1.

[0119] Table 1 Determination of Al in actual water samples and soil samples by compound 3a 3+

[0120]

[0121]

[0122] As can be seen from Table 1, the recovery rate range of compound 3a for low-concentration Al 3+ (10 -5 M) is 95.5 - 107%, and the RSD is less than 3.16%. These results indicate that compound 3a shows high accuracy in identifying Al 3+ in actual samples and is suitable for detecting Al 3+ in actual water samples and soil samples.

[0123] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. An application of a salicylaldehyde Schiff base fluorescent probe in detecting aluminum ions, characterized in that: The compound structural formula of the salicylaldehyde Schiff base fluorescent probe is shown in Formula A: Wherein, Ar is benzimidazolyl, benzothiazolyl or 2-aminopyridine.

2. The use of the salicylaldehyde Schiff base fluorescent probe in detecting aluminum ions according to claim 1, characterized in that: The salicylaldehyde Schiff base fluorescent probe is prepared by a preparation method comprising the following steps: The heterocyclic amino compound reacts with 5-methyl salicylaldehyde to obtain the salicylaldehyde Schiff base fluorescent probe; the heterocyclic amino compound is selected from 2-aminobenzimidazole, 2-aminobenzothiazole or 2-aminopyridine.

3. The use of the salicylaldehyde Schiff base fluorescent probe in detecting aluminum ions according to claim 1, characterized in that: The solution system for detecting aluminum ions with the salicylaldehyde Schiff base fluorescent probe is N,N-dimethylformamide-water solution or pure N,N-dimethylformamide.

4. A method for detecting aluminum ions, characterized in that: The method comprises the following steps: preparing a probe solution with the salicylaldehyde Schiff base fluorescent probe according to any one of claims 1 to 3, wherein the solvent of the detection system is N,N-dimethylformamide-water solution or pure N,N-dimethylformamide, adding the solution to be detected, and detecting the presence of aluminum ions if the detection system emits yellow-green fluorescence; Alternatively, a fluorescence spectrum detection method is used, using 405 nm fluorescence as the excitation light, monitoring and detecting fluorescence changes to obtain fluorescence data, and if the fluorescence intensity of the fluorescence emission peak of the fluorescent probe is enhanced, the presence of aluminum ions is detected.

5. The method for detecting aluminum ions according to claim 4, characterized in that: The method specifically comprises the following steps: monitoring and detecting the fluorescence variation range of the wavelength of 400-750nm to obtain fluorescence data; if the fluorescence intensity of the fluorescence emission peak of the fluorescent probe at 508-510nm is enhanced, the presence of aluminum ions is detected.

6. The method for detecting aluminum ions according to claim 4, characterized in that: The volume ratio of N,N-dimethylformamide to water in the N,N-dimethylformamide-water solution is (7-11):

1.

7. The method for detecting aluminum ions according to claim 4, characterized in that: The solution to be detected is added to the probe solution in the form of a N,N-dimethylformamide solution to be detected.

8. A test paper for detecting aluminum ions, characterized in that: The test paper is a test paper or filter paper loaded with the salicylaldehyde Schiff base fluorescent probe according to any one of claims 1 to 3.

9. A method for detecting aluminum ions using test paper, characterized in that: The method comprises the following steps: dripping the solution to be detected onto the test paper as claimed in claim 8, and then observing the test paper under an ultraviolet lamp. If the test paper shows blue fluorescence, the presence of aluminum ions is detected.

10. A method for detecting aluminum ions in soil, characterized in that: The method comprises the following steps: soaking the soil sample to be detected in N,N-dimethylformamide-water solution or pure N,N-dimethylformamide, filtering to obtain the solution to be detected, and then using the method for detecting aluminum ions according to any one of claims 4 to 7 to detect the solution to be detected.

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