WO2023093399A1

WO2023093399A1 - Benzothiazole-parent-based fluorescent probe for detection of palladium ions, and preparation method therefor and use thereof

Info

Publication number: WO2023093399A1
Application number: PCT/CN2022/126624
Authority: WO
Inventors: 蒋春辉; 陆鸿飞; 邵琦; 郑绍军; 陈梁
Original assignee: 江苏科技大学
Priority date: 2021-11-25
Filing date: 2022-10-21
Publication date: 2023-06-01
Also published as: CN113912596B; CN113912596A

Abstract

Disclosed in the present invention are a benzothiazole-parent-based fluorescent probe for the detection of palladium ions, and a preparation method therefor and the use thereof. The structural formula of the fluorescent probe is as shown in formula (I) below. With a benzothiazole derivative as a fluorophore and an amino as a linking group, the prepared fluorescent probe shows high sensitivity and high selectivity for Pd²⁺ in a solution, and also has the characteristic of a stable structure. The preparation method for the fluorescent probe has simple steps and uses easily available raw materials, and the obtained product is a solid powder, is easy to store, has wide application prospects, and can be produced and applied on a large scale.

Description

A kind of palladium ion detection fluorescent probe based on benzothiazole parent and its preparation method and application

technical field

The invention belongs to the technical field of fluorescent probes, and in particular relates to a palladium ion detection fluorescent probe based on a benzothiazole parent and its preparation method and application.

Background technique

Palladium is a very important transition metal element, which belongs to the platinum group metal elements. It is widely used in jewelry industry, electronics and electrical industry, industrial catalysis industry and fuel cell industry, etc. Palladium is one of the most important catalysts in catalytic converters of automobile exhaust emission devices. During the normal driving of automobiles, the emission speed of palladium ions is 0.1-0.8μg·km ^-1 ·car ^-1 , so on both sides of the expressway The content of palladium ions on the facilities and plant leaves is very high. In addition, palladium is a very important catalyst in the chemical and pharmaceutical fields. It can catalyze coupling reactions such as Suzuki reaction, Heck reaction and Sonogashira reaction. There is a large amount of palladium in the wastewater of laboratories, chemical industry, pharmaceuticals, pesticides and other factories. residual. Studies have shown that palladium ions are the second largest metal sensitizer besides nickel ions, especially palladium chloride, which can strongly irritate the skin and eyes of humans and animals after contact. In addition, after palladium ions enter the human body, due to their very strong coordination properties, they can coordinate with important biological macromolecules in the human body, such as sulfur-containing amino acids, DNA, RNA, protein and vitamin B6, thereby inhibiting many of the cells. Normal function, which leads to diseases such as asthma, allergies, conjunctivitis and so on. In view of the serious hazards of palladium ions, the European Medicines Supervision Center stipulates that the content of palladium in medicines should be lower than 0.005‰～0.01‰. Therefore, it is very necessary to detect palladium ions quickly and efficiently.

Traditional instrumental methods for detecting palladium ions include atomic absorption spectrometry, plasma emission spectrometry, solid state microextraction high performance liquid chromatography, X-ray fluorescence and inductively coupled plasma mass spectrometry. These methods can meet the requirements of determination under certain conditions, but there are also many disadvantages, such as sample pretreatment, detection is not fast enough, detection is expensive, complex instruments and skilled operators are required, and so on.

The fluorescence analysis method uses fluorescence as the output signal. Compared with the above methods, it has the characteristics of high sensitivity, good selectivity, easy operation, and low price. It can not only be detected in the solution, but also can be observed on the interface. Therefore, the design It is of great practical significance to develop highly sensitive and highly selective Pd ²⁺ probes.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a palladium ion detection fluorescent probe based on a benzothiazole parent and its preparation method and application. The fluorescent probe compound is a benzothiazole-based parent and can rapidly detect ^{Pd +} Schiff base-type fluorescent probe, which has the advantages of specific recognition, short response time and high sensitivity for palladium ions.

In order to solve the problems of the prior art, the technical scheme that the present invention takes is:

A kind of palladium ion detection fluorescent probe based on benzothiazole parent, its structural formula is as follows:

The preparation method of the above-mentioned palladium ion detection fluorescent probe based on the benzothiazole parent comprises the following steps:

S1. Condensation reaction of 2-aminothiophenol and 2-aminobenzaldehyde to obtain 2-(2-aminophenyl)benzothiazole, the structure of which is the intermediate of formula (II)

S2, take 3-methyl-1-phenyl-2-pyrazolin-5-one as raw material, add DMF, POCl ₃ carry out addition reaction in organic solvent, obtain 3-methyl-1-phenyl- 2-Pyrazolin-5-one-4-carbaldehyde, the structure is as the intermediate of formula (Ⅲ)

S3, dissolving the intermediate of formula (II) and intermediate of formula (III) in an organic solvent for Schiff base reaction to obtain 4-(((2-amino-benzothiazole)phenyl)imino)methyl) -5-Methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, the structure is as formula (I)

Its reaction scheme is as follows:

Preferably, the steps of step S1 are: 2-aminothiophenol and 2-aminobenzaldehyde are added in acetic acid successively, heated, after the reaction is complete, sodium bicarbonate aqueous solution is added, and dichloromethane is used for extraction, and finally Anhydrous sodium sulfate was added to remove water, and after suction filtration, the filtrate was distilled off under reduced pressure to remove the organic solvent, and the crude product was purified by recrystallization to obtain the intermediate of formula (II).

Preferably, step S2 is: add 3-methyl-1-phenyl-2-pyrazolin-5-one into DMF, first slowly add POCl ₃ dropwise under ice-water bath conditions, and wait until the dropwise addition is completed Afterwards, high-temperature reflux reaction, and then after cooling to room temperature, adding water, reaction at room temperature, and suction filtration to obtain the intermediate of formula (Ⅲ).

Preferably, the steps of step S3 are as follows: dissolve the intermediate of formula (II) and intermediate of formula (III) in an organic solvent, and then reflux and stir. After the reaction is completed, filter with suction and wash the solid with ice ethanol to obtain fluorescent probe.

Application of the above-mentioned palladium ion detecting fluorescent probe in detecting palladium ion in solution.

Beneficial effect:

Compared with the prior art, the present invention has a palladium ion detection fluorescent probe based on benzothiazole parent and its preparation method and application. The specific advantages are as follows:

1. The present invention uses benzothiazole derivatives and 3-methyl-1-phenyl-2-pyrazolin-5-one-4-formaldehyde as fluorescent groups and amino as connecting groups to synthesize a The palladium ion fluorescent probe of the benzothiazole parent has easy-to-obtain raw materials and a simple method, and the obtained product is a solid powder, which is easy to store and has good stability;

2. The benzothiazole derivatives are selected as the flat steel plane, which has the advantages of low biological toxicity and strong binding ability between nitrogen atoms and metals;

3. The fluorescent probe has specific recognition for palladium ions, short response time, high sensitivity, high sensitivity and high selectivity to trace Pd ²⁺ in solution, and it has the characteristics of stable structure.

Description of drawings

Fig. 1 is the fluorescence detection of the palladium ion fluorescent probe prepared in Example 1 on the fluorescent probe itself and after adding palladium ion (Pd ²⁺ ) in EtOH-H ₂ O (v/v=9:1) solution. The UV absorption spectrum of the needle;

Fig. 2 is the selective fluorescence spectrogram of the palladium ion fluorescent probe prepared in Example 1 to different metal ions in EtOH-H ₂ O (v/v=9:1) solution;

Fig. 3 is the fluorescence spectrum response diagram of the fluorescent probe prepared in Example 1 to different concentrations of palladium ions (Pd ²⁺ ) in EtOH-H ₂ O (v/v=9:1) solution;

Fig. 4 is the fluorescence response diagram of the fluorescent probe prepared in Example 1 in the EtOH-H ₂ O (v/v=9:1) solution to different metal ion selective interference detection;

Fig. 5 is the Job-plot curve of the complexation ratio of the fluorescent probe prepared in Example 1 in EtOH-H ₂ O (v/v=9:1) and palladium ion (Pd ²⁺ );

Fig. 6 is the probe test paper and the palladium ion of different concentrations prepared by the fluorescent probe prepared in embodiment 1;

Fig. 7 is the response time figure when the fluorescent probe that makes in embodiment 1 detects palladium ion;

Fig. 8 is the mass spectrum MS spectrogram of the fluorescent probe prepared in embodiment 1;

Fig. 9 is the nuclear magnetic resonance ¹ H-NMR spectrogram of the fluorescent probe prepared in embodiment 1;

FIG. 10 is the nuclear magnetic resonance ¹³ C-NMR spectrum of the fluorescent probe prepared in Example 1.

Detailed ways

The specific implementation of the present invention will be further described below in conjunction with the examples. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

The experimental methods used in the present invention are conventional methods unless otherwise specified. The materials and reagents used in the experiment can be obtained from commercial sources unless otherwise specified. All the following reagents used in the examples are commercially available analytically pure or chemically pure.

Among them, various metal ion solutions in the embodiments are prepared by adding deionized water to chloride salt chemical reagents such as anhydrous zinc chloride and anhydrous ferric chloride with a purity of more than 99%.

Embodiment 1 prepares the palladium ion fluorescent probe compound of benzothiazole parent

S1 preparation formula II intermediate (2-(2-aminophenyl) benzothiazole)

In a 10mL Shrek tube, add 2-aminothiophenol (626mg, 5mmol) and 2-aminobenzaldehyde (606mg, 5mmol) and dissolve in 2mL acetic acid, then heat and stir at 110°C for 2h. Cool to room temperature after the reaction is complete. Then all the obtained crude products were dissolved in 20 mL of saturated aqueous sodium bicarbonate solution, and the mixture was extracted 3 times with dichloromethane, then dehydrated with saturated brine, dried, and dichloromethane was distilled off under reduced pressure to obtain the crude product . The crude product was purified and eluted with EA/PE (v/v, 1:200), and the intermediate of formula II was obtained after vacuum distillation as a white powder (927.3 mg, yield 82%). 1H NMR (600MHz, DMSO-d6) δ8.08(d, J＝8.0Hz, 1H), 8.01(d, J＝8.1Hz, 1H), 7.64(dd, J＝7.9, 1.4Hz, 1H), 7.51 (ddd, J=8.1,7.4,1.0Hz,1H),7.41(ddd,J=7.9,7.3,0.9Hz,1H),7.33(s,2H),7.22(ddd,J=8.3,7.3,1.4Hz ,1H),6.89(dd,J＝8.3,1.0Hz,1H),6.65(ddd,J＝8.0,7.0,0.9Hz,1H).13C NMR(150MHz,DMSO-d6)δ168.8,153.2,147.6,132.4 ,131.8,129.9,126.4,125.1,122.0,121.7,116.5,115.6,113.2.

The structural formula of gained formula II intermediate is:

S2 preparation formula III intermediate (3-methyl-1-phenyl-2-pyrazolin-5-one-4-carbaldehyde)

In a 50mL two-necked flask, 3-methyl-1-phenyl-2-pyrazolin-5-one (1g, 5.5mmol) was dissolved in 2.7mL DMF, and 1.6mL phosphorus oxychloride was added dropwise. After the dropwise addition, the reaction solution was refluxed and stirred for 1 h at high temperature. After the heating was completed, 20 mL of water was added after cooling to room temperature, and then stirred overnight, and the intermediate of formula III was obtained by suction filtration. As a yellow solid (0.71 g, 64% yield). 1H NMR(CDCl ₃ ,200MHz)d 1.2(s,3H,CH3),7.3–7.9(m,6H,Ph),9.85(s,1H,CHO).13C NMR(50MHz,CDCl ₃ )d 17.0,116.9 ,125.5,129.8,133.9,134.6,137.1,155.7,181.5.

The structural formula of gained formula III intermediate is:

S3 preparation of palladium ion fluorescent probe compound based on benzothiazole parent

Add the intermediate of formula II (226mg, 1mmol) and the intermediate of formula III (303mg, 1.5mmol) into a 50mL round-bottomed flask, dissolve in 5mL of ethanol, and after the solid is dissolved, reflux and stir at 80°C for 4h until the reaction is complete Afterwards, the reactant was cooled to room temperature, suction filtered, and the solid was washed with ice ethanol to obtain the intermediate of formula I as a light yellow powder (324.3 mg, yield 79%).

The resulting fluorescent probe compound structural formula is:

The mass spectrum MS spectrum is shown in Figure 8.

The nuclear magnetic resonance ¹ H-NMR spectrum of the palladium ion fluorescent probe compound based on the benzothiazole parent: ¹ H NMR (400MHz, Chloroform-d) δ8.55–8.44(m,1H),8.11–8.04(m,1H ),7.88–7.77(m,1H),7.51(ddd,J=8.3,7.2,1.2Hz,2H),7.43(d,J=1.6Hz,1H),7.41(d,J=1.4Hz,1H) ,7.39(s,1H),7.37(d,J=1.1Hz,1H),7.36(m,1H),7.33(m,1H),7.24–7.14(m,2H),7.07(m,1H), 3.40(s,1H), 2.25(s,3H), see Figure 9.

The nuclear magnetic resonance ¹³ C-NMR spectrum of the palladium ion fluorescent probe compound based on the benzothiazole parent: ¹³ C NMR (101MHz, Chloroform-d) δ164.83, 163.21, 152.47, 147.42, 139.11, 138.29, 137.14, 132.67, 130.58, 129.77, 127.68, 125.91, 123.55, 123.18, 122.90, 120.17, 120.08, 117.50, 114.07, 104.50, 11.86, see Figure 10.

Embodiment 2 Performance test of palladium ion fluorescent probe

1. The ultraviolet absorption of the fluorescent probe of palladium ion to the fluorescent probe itself and the fluorescent probe after adding palladium ion (Al ³⁺ ) in EtOH-H ₂ O (v/v=9:1) solution

The palladium ion detection fluorescent probe prepared in Example 1 was configured into a 1mM probe stock solution with DMSO, each metal ion was configured into a 3mM metal ion stock solution with deionized water, and added to 3mL blank solution EtOH-H ₂ O Add 30 μL of probe stock solution and 50 μL of metal ion stock solution into (v/v=9:1) and detect with fluorescence spectrometer and ultraviolet spectrophotometer. The test shows that the maximum excitation wavelength of the fluorescent probe is 372nm, and the maximum emission The wavelength is 444nm;

Take 3mL of the blank solution EtOH-H ₂ O (v/v=9:1) to neutralize 30μL of the probe stock solution, and add 0, 1, 2, 3...50, 55, 60μL of the probe stock solution in sequence , for UV spectroscopy. The test results show that with the continuous increase of palladium ions, the absorbance at λ=303nm decreases, while the absorbance at λ=348nm increases. When the concentration of palladium ions is 45μM, the absorbance at 348nm tends to reach the maximum and then tends to balance . Before the concentration of palladium ion is lower than 45 μM, the absorbance of ultraviolet absorption, the absorbance of palladium ion and probe complex at 348nm and the concentration of palladium ion have a good linear relationship, as shown in Figure 1.

2. Selective recognition of Pd ²⁺ by palladium ion fluorescent probe

Add ₃₀ μL of probe stock solution and 50 μL of various metal ion stock solutions (Al ³⁺ , Pd ²⁺ , Cu ²⁺ , Ni ²⁺ , Ag ⁺ , Co ²⁺ , Fe ²⁺ , Cr ³⁺ , Fe ³⁺ , Sn ²⁺ , Cd ²⁺ , Ca ²⁺ , Mg ²⁺ , K ⁺ , Pb ²⁺ , Na ⁺ , Mn ^{2 +} , Ba ²⁺ , Cu ⁺ , Zn ²⁺ ). The result shows that when palladium ions are added, the fluorescence spectrum obviously weakens at 444nm, and when other metal ions are added, the fluorescence does not change significantly, that is, the fluorescent probe of the present invention has good selectivity to palladium ions, see figure 2.

3. Effect of palladium ion concentration on fluorescence intensity of palladium ion fluorescent probe

Fluorescence spectrum test _of different concentrations of palladium ions (Pd ²⁺ ): add 30 μL of probe stock solution and 0-60 μL (0, 1, 2, 3 ... 50, 55, 60 μL) of palladium ion solution (3mM aluminum ion stock solution), the fluorescent probe itself has a strong fluorescence in the solution, but with the increase of palladium ion concentration, the fluorescence at 444nm also increases. It is constantly weakening, indicating that the fluorescence intensity decreases with the increase of the palladium ion concentration. The addition of palladium ions causes the fluorescence color of the probe solution to change from bright blue to light blue under the irradiation of a 365nm ultraviolet lamp. The results show that the probe has high sensitivity to Pd ²⁺ , as shown in Figure 3.

4. Interference of coexisting ions on the palladium ion fluorescent probe

Interference test of different _metal ions for palladium ion detection fluorescent probe: add 30 μL of probe stock solution and 50 μL of any other metal ion ( Co ²⁺ , Ni ²⁺ , Al ³⁺ , Mn ²⁺ , Mg ²⁺ , Ba ²⁺ , Pb ²⁺ , Fe ²⁺ , Cd ²⁺ , K ⁺ , Ca ²⁺ , Cs ²⁺ , Na ⁺ , Ag ⁺ and Cu ²⁺ ) stock solution, and finally 50 μL of Pd ²⁺ stock solution was added to the blank solution to test its fluorescence intensity. The presence of other metal ions has no obvious interference on the recognition of aluminum ions by the aluminum ion fluorescent probe compound of the present invention, as shown in FIG. 4 .

5. The effect of the amount ratio of palladium ion and fluorescent probe substance on the fluorescence intensity

Study the binding rate of the probe to Pd ²⁺ by the Job's plot method: add a certain volume of probe stock solution (1mM) and Pd ²⁺ stock to 3mL blank solution EtOH-H ₂ O (v/v=9:1) Solution (3mM), so that the concentration sum of the palladium ion detection fluorescent probe and palladium ion is 50 μ M, by changing the concentration ratio of the two (the amount ratio of palladium ion detection fluorescent probe and palladium ion substance is 1:9, 2: 8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1) to plot the fluorescence intensity at 444 nm and the ratio of ions to the total concentration. When the proportion of aluminum ions is 0.5, the ordinate reaches the lowest value, and it can be determined that the fluorescent probe compound and palladium ions are mainly combined in a 1:1 form to form a stable complex, as shown in FIG. 5 .

6. Detection of different concentrations of palladium ions by probe test paper

The filter paper was immersed in the EtOH-H ₂ O (v/v=9:1) stock solution containing the fluorescent probe (1 mM), soaked for half an hour, and then the test strip was taken out and dried in the air to obtain a dry probe-containing test strips. The test strips were respectively soaked in 0mM, 0.3mM, 1mM palladium ion concentration solutions, soaked for a few minutes, and dried, and a band of rapid discoloration was observed under a 365nm ultraviolet lamp, indicating that the probe of the present invention can be detected in a solid state Palladium ion, see Figure 6.

7. Response time of fluorescent probes to detect palladium ions

Add only 30 μL of probe stock solution to 3 mL of blank buffer solution EtOH-H ₂ O (v/v=9:1), followed by adding 30 μL of probe stock solution and 50 μL of Pd ²⁺ stock solution, the probe The fluorescence intensity gradually weakened to the weakest, and reached the lowest value within 2.5 minutes and the fluorescence intensity of the probe tended to be stable, which indicated that the probe was stable enough for Pd ²⁺ detection, and the speed was fast, and only 30 μL of The fluorescence intensity of the probe stock solution tended to be stable, as shown in Figure 7.

The present invention uses benzothiazole derivatives and 3-methyl-1-phenyl-2-pyrazolin-5-one-4-carbaldehyde as fluorescent groups and amino as linking groups to synthesize a benzothiazole-based The palladium ion fluorescent probe of the thiazole parent, the preparation method is easy to get raw materials, the method is simple, the obtained product is a solid powder, easy to store, has specific recognition for palladium ions, short response time, high sensitivity, and is sensitive to trace amounts of Pd in the solution. ²⁺ exhibits high sensitivity and high selectivity, and at the same time it has the characteristics of stable structure.

The above is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention can obviously obtain the simplicity of the technical solution. Changes or equivalent replacements all fall within the protection scope of the present invention.

Claims

A palladium ion detection fluorescent probe based on a benzothiazole parent is characterized in that its structural formula is as follows:
A kind of preparation method based on the palladium ion detection fluorescent probe of benzothiazole parent according to claim 1, is characterized in that, comprises the following steps:

S1. Condensation reaction of 2-aminothiophenol and 2-aminobenzaldehyde to obtain 2-(2-aminophenyl)benzothiazole, the structure of which is the intermediate of formula (II)

S2. Using 3-methyl-1-phenyl-2-pyrazolin-5-one as raw material, add DMF, POCl 3 , and perform addition reaction in an organic solvent to obtain 3-methyl-1-phenyl -2-Pyrazolin-5-one-4-carbaldehyde, the structure is as an intermediate of formula (Ⅲ)

S3, dissolving the intermediate of formula (II) and intermediate of formula (III) in an organic solvent for Schiff base reaction to obtain 4-(((2-amino-benzothiazole)phenyl)imino)methyl) -5-Methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, the structure is as formula (I)
A kind of preparation method of the palladium ion detection fluorescent probe based on benzothiazole parent according to claim 2, is characterized in that, the step of step S1 is: 2-aminothiophenol and 2-aminobenzaldehyde add acetic acid successively medium, heating, after the reaction is complete, add sodium bicarbonate aqueous solution, then extract with dichloromethane, finally add anhydrous sodium sulfate to remove water, after suction filtration, distill the filtrate under reduced pressure to remove the organic solvent, and pass the crude product through heavy Purified by crystallization to obtain the intermediate of formula (II).
A kind of preparation method of the palladium ion detection fluorescent probe based on benzothiazole parent according to claim 2, is characterized in that, step S2 is: 3-methyl-1-phenyl-2-pyrazoline- Add 5-ketone into DMF, first slowly add POCl 3 dropwise under the condition of ice-water bath, after the dropwise addition is completed, reflux reaction at high temperature, then after cooling to room temperature, add water, react at room temperature, and suction filter to obtain formula (Ⅲ ) intermediates.
A method for preparing a benzothiazole parent-based palladium ion detection fluorescent probe according to claim 2, characterized in that the steps of step S3 are as follows: dissolving the intermediate of formula (II) and the intermediate of formula (III) In an organic solvent, reflux and stir again, after the reaction is completed, filter with suction, and wash the solid with ice ethanol to obtain a fluorescent probe.
Based on the application of the palladium ion detection fluorescent probe described in claim 1 or claim 2 in detecting palladium ions in the solution.