Molecular fluorescent probe for detecting Hg < 2 + > as well as preparation method and application of molecular fluorescent probe

Abstract

The preparation method comprises the following steps: reacting phenoxazine with 1-bromoethane to obtain a compound A, then generating a compound B under the action of DMF (Dimethyl Formamide) and POCl3, and then reacting the compound B with 1, 3-indandione to obtain the molecular fluorescent probe for detecting Hg < 2 + >. The molecular fluorescent probe has the advantages of simple structure, convenience in synthesis, easily available raw materials, low cost, strong selectivity, high sensitivity and the like, and has important practical application value in detection of Hg < 2 + >-containing samples in the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis and analytical chemistry, and more particularly to a method for detecting Hg 2+ Molecular fluorescent probe and its preparation method and application. Background Art

[0002] Mercury is the only liquid metal at room temperature. It is fluid and one of the most toxic heavy metal pollutants. It is widely present in water, air and soil. Currently, there are more than 80 kinds of industrial production in the world that require mercury as raw material or auxiliary material. It is estimated that 5,000 tons of mercury are discharged into the environment every year. Mercury in the environment can enter organisms through the food chain and accumulate in the body, causing damage to the human respiratory system and central nervous system, causing cerebral palsy, mental retardation, etc. It also threatens the liver and kidneys, seriously damaging human health.

[0003] As the harm caused by mercury ions to the environment and human health is becoming increasingly serious, researchers have developed and widely used many mercury ion detection methods such as electrochemical method, atomic emission spectroscopy, spectrophotometry, inductively coupled plasma mass spectrometry, atomic absorption spectroscopy and gas chromatography. Due to the characteristics of being able to detect multiple elements at the same time and rapid analysis, these conventional detection technologies are increasingly widely used in various fields. However, these methods still have many shortcomings, such as the need for expensive experimental instruments, harsh sample pretreatment conditions, high requirements for test personnel, complex instrument structure and inability to perform real-time monitoring. In order to protect the environment and maintain ecological balance, it is urgent to construct a simple, rapid and highly sensitive method for detecting mercury ions.

[0004] Fluorescence probe method has the characteristics of high sensitivity, high selectivity, simple and fast operation, etc., and has attracted more and more attention and gradually become a research hotspot in the field of rapid detection technology. At present, many fluorescent probes for mercury ion detection have been reported. Kumar's research group has developed a highly selective and sensitive chemical sensor for Hg 2+ The Shen group designed and synthesized a dual colorimetric and fluorescent detection method for Hg 2+The Tian group designed and synthesized a new type of naphthalene imide-based fluorescent probe (Acs Omega, 2020, 5(29): 18176-18184) using 1,2-dithioalkyl as the recognition group. Although many optical probes with excellent performance have been developed for the detection of Hg 2+ However, it still has disadvantages such as complicated preparation process, inexpensive and easy-to-obtain raw materials, slow response and poor selectivity. It also shows poor water solubility and detection limit.

[0005] Therefore, how to develop a simple, rapid and highly sensitive method to detect Hg 2+ The fluorescent probes are an urgent problem to be solved by technicians in this field. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a method for detecting Hg 2+ Molecular fluorescent probes and preparation methods and applications thereof are provided to address the deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for detecting Hg 2+ The molecular fluorescent probe has the structural formula:

[0009] A method for detecting Hg 2+ The method for preparing a molecular fluorescent probe comprises the following steps:

[0010] (1) at room temperature, phenoxazine, anhydrous DMSO (dimethyl sulfoxide) solution, sodium hydroxide and 1-bromoethane are mixed and stirred for reaction. After the reaction is completed, the reaction solution is quenched with water and extracted with ethyl acetate. The organic phase is separated and dried with anhydrous MgSO4 (magnesium sulfate). The solvent is removed and the residue is purified by column chromatography to obtain compound A;

[0011] The structural formula of compound A is:

[0012] (2) Under low temperature conditions, compound A, anhydrous DMF (N,N-dimethylformamide), POCl3 (phosphorus oxychloride) and anhydrous 1,2-dichloroethane are mixed and heated to reflux for reaction. After the reaction is completed, the reaction solution is quenched with 20% (mass fraction) NaOH (sodium hydroxide) solution, extracted with water and dichloromethane, the organic phase is separated and dried over anhydrous MgSO4, the solvent is removed in vacuo, and the residue is purified by column chromatography to obtain compound B;

[0013] The structural formula of compound B is:

[0014] (3) Compound B, 1,3-indandione, anhydrous ethanol and potassium methoxide are mixed, heated for reaction, and the reaction is monitored by TLC until the raw material point disappears. The mixture is cooled, precipitated, filtered, washed with anhydrous ethanol, dried over anhydrous MgSO4, and purified by column chromatography to obtain a product for detecting Hg. 2+ Molecular fluorescent probes.

[0015] The synthetic route of the molecular fluorescent probe of the present invention is:

[0016]

[0017] Furthermore, in the above step (1), the usage ratio of phenoxazine, anhydrous DMSO solution, sodium hydroxide and 1-bromoethane is 0.01 mol: 30 mL: 0.05 mol: 0.02 mol.

[0018] Furthermore, in the above step (1), the stirring reaction time is 12-24 hours, preferably 18 hours.

[0019] Furthermore, in the above step (1), the eluent used in the column chromatography method is ethyl acetate:petroleum ether=1:5.

[0020] Furthermore, in the above step (2), the usage ratio of compound A, anhydrous DMF, POCl3 and anhydrous 1,2-dichloroethane is 5.5mmol:3mL:5mL:25mL.

[0021] Furthermore, in the above step (2), the low temperature condition is (-20)-0°C, preferably -10°C; the temperature of the heating reflux reaction is 50-150°C, preferably 100°C; and the time of the heating reflux reaction is 12-36h, preferably 24h.

[0022] Furthermore, in the above step (2), the eluent used in the column chromatography method is ethyl acetate: dichloromethane = 1:10 (volume ratio).

[0023] Furthermore, in the above step (3), the usage ratio of compound B, 1,3-indandione, anhydrous ethanol and potassium methoxide is 4.2 mmol:5 mmol:20 mL:0.06 mmol.

[0024] Furthermore, in the above step (3), the heating reaction temperature is 50-120°C, preferably 90°C; the heating reaction time is 4-12h, preferably 8h.

[0025] Furthermore, in the above step (3), the developing solvent for TLC monitoring is dichloromethane: petroleum ether = 1:1 (volume ratio).

[0026] Furthermore, in the above step (3), the eluent used in the column chromatography method is dichloromethane: petroleum ether = 1:2 (volume ratio).

[0027] The present invention also claims a molecular fluorescent probe or a molecular fluorescent probe prepared by the above preparation method for detecting Hg 2+ Application in.

[0028] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The ethylphenoxazine in the present invention uses its electron-rich structure as an electron donor and has a rigid planar conjugated large π bond system as a fluorescent group, with 1,3-indandione as an acceptor, Hg 2+ The structure of the molecular fluorescent probe of the present invention can be changed so as to be detected by an instrument.

[0030] 2. The molecular fluorescent probe of the present invention has the advantages of simple structure, convenient synthesis, easy availability of raw materials, low cost, strong selectivity and high sensitivity. 2+ The sample detection has important practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The compound A obtained in step (1) of Example 2 1 H NMR spectrum (CDCl3, 500 MHz);

[0032] Figure 2 The compound A obtained in step (1) of Example 2 13 C NMR spectrum (CDCl3, 125 MHz);

[0033] Figure 3 is the compound B obtained in step (2) of Example 2 1 H NMR spectrum (CDCl3, 500 MHz);

[0034] Figure 4 is the compound B obtained in step (2) of Example 2 13 C NMR spectrum (CDCl3, 125 MHz);

[0035] Figure 5 The molecular fluorescent probe prepared in step (3) of Example 2 1 H NMR spectrum (CDCl3, 500 MHz);

[0036] Figure 6 The molecular fluorescent probe prepared in step (3) of Example 2 13 C NMR spectrum (CDCl3, 125 MHz);

[0037] Figure 7 The fluorescence spectra of the molecular fluorescent probe prepared in step (3) of Example 2 in the presence of different metal ions. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] For detection of Hg 2+ The molecular fluorescent probe has the structural formula:

[0041] Example 2

[0042] In Example 1, Hg 2+ The method for preparing a molecular fluorescent probe comprises the following steps:

[0043] (1) At room temperature, phenoxazine (1.83 g, 0.01 mol), anhydrous DMSO solution (30 mL) and solid sodium hydroxide (2 g, 0.05 mol) were added to a round-bottom flask, mixed, and 1-bromoethane (1.49 mL, 0.02 mol) was added dropwise under nitrogen protection, and the reaction was stirred for 18 h. After the reaction was completed, the reaction solution was quenched with water and extracted with ethyl acetate. The organic phase was separated and dried over anhydrous MgSO4, and the solvent was removed. The residue was purified by column chromatography with an eluent of ethyl acetate: petroleum ether = 1:5 to obtain compound A;

[0044] (2) Under low temperature conditions of (-20)-0°C, compound A (1.16 g, 5.5 mmol), anhydrous DMF (3 mL), POCl3 (5 mL) and anhydrous 1,2-dichloroethane (25 mL) were added to a round-bottom flask, mixed, heated to 100°C and refluxed for 24 h. After the reaction, the reaction solution was quenched with 20% NaOH solution, extracted with water and dichloromethane, the organic phase was separated and dried over anhydrous MgSO4, the solvent was removed in vacuo, and the residue was purified by column chromatography with an eluent of ethyl acetate: dichloromethane = 1:10 to obtain compound B;

[0045] (3) Compound B (1.00 g, 4.2 mmol), 1,3-indandione (0.73 g, 5 mmol), anhydrous ethanol (20 mL) and potassium methoxide (4.21 mg, 0.06 mmol) were added to a round-bottom flask, mixed, heated to 90° C. for 8 h, and the reaction was monitored by TLC until the raw material point disappeared. The developing solvent was dichloromethane: petroleum ether = 1:1. The mixture was cooled, precipitated, filtered, washed with anhydrous ethanol, dried over anhydrous MgSO4, and purified by column chromatography. The eluent was dichloromethane: petroleum ether = 1:2 to obtain a product for detecting Hg. 2 + Molecular fluorescent probes.

[0046] Example 3

[0047] In Example 1, Hg 2+ The method for preparing a molecular fluorescent probe comprises the following steps:

[0048] (1) At room temperature, phenoxazine (1.83 g, 0.01 mol), anhydrous DMSO solution (30 mL) and solid sodium hydroxide (2 g, 0.05 mol) were added to a round-bottom flask, mixed, and 1-bromoethane (1.49 mL, 0.02 mol) was added dropwise under nitrogen protection, and the reaction was stirred for 12 h. After the reaction was completed, the reaction solution was quenched with water and extracted with ethyl acetate. The organic phase was separated and dried over anhydrous MgSO4, and the solvent was removed. The residue was purified by column chromatography with an eluent of ethyl acetate: petroleum ether = 1:5 to obtain compound A;

[0049] (2) Under low temperature conditions of (-20)-0°C, compound A (1.16 g, 5.5 mmol), anhydrous DMF (3 mL), POCl3 (5 mL) and anhydrous 1,2-dichloroethane (25 mL) were added to a round-bottom flask, mixed, heated to 50°C and refluxed for 36 h. After the reaction, the reaction solution was quenched with 20% NaOH solution, extracted with water and dichloromethane, the organic phase was separated and dried over anhydrous MgSO4, the solvent was removed in vacuo, and the residue was purified by column chromatography with an eluent of ethyl acetate: dichloromethane = 1:10 to obtain compound B;

[0050] (3) Compound B (1.00 g, 4.2 mmol), 1,3-indandione (0.73 g, 5 mmol), anhydrous ethanol (20 mL) and potassium methoxide (4.21 mg, 0.06 mmol) were added to a round-bottom flask, mixed, heated to 50° C. for 12 h, and the reaction was monitored by TLC until the raw material point disappeared. The developing solvent was dichloromethane: petroleum ether = 1:1. The mixture was cooled, precipitated, filtered, washed with anhydrous ethanol, dried over anhydrous MgSO4, and purified by column chromatography. The eluent was dichloromethane: petroleum ether = 1:2 to obtain a product for detecting Hg.2 + Molecular fluorescent probes.

[0051] Example 4

[0052] In Example 1, Hg 2+ The method for preparing a molecular fluorescent probe comprises the following steps:

[0053] (1) At room temperature, phenoxazine (1.83 g, 0.01 mol), anhydrous DMSO solution (30 mL) and solid sodium hydroxide (2 g, 0.05 mol) were added to a round-bottom flask, mixed, and 1-bromoethane (1.49 mL, 0.02 mol) was added dropwise under nitrogen protection, and the reaction was stirred for 24 h. After the reaction was completed, the reaction solution was quenched with water and extracted with ethyl acetate. The organic phase was separated and dried over anhydrous MgSO4, and the solvent was removed. The residue was purified by column chromatography with an eluent of ethyl acetate: petroleum ether = 1:5 to obtain compound A;

[0054] (2) Under low temperature conditions of (-20)-0°C, compound A (1.16 g, 5.5 mmol), anhydrous DMF (3 mL), (POCl35 mL) and anhydrous 1,2-dichloroethane (25 mL) were added to a round-bottom flask, mixed, heated to 150°C and refluxed for 12 h. After the reaction, the reaction solution was quenched with 20% NaOH solution, extracted with water and dichloromethane, the organic phase was separated and dried over anhydrous MgSO4, the solvent was removed in vacuo, and the residue was purified by column chromatography with an eluent of ethyl acetate: dichloromethane = 1:10 to obtain compound B;

[0055] (3) Compound B (1.00 g, 4.2 mmol), 1,3-indandione (0.73 g, 5 mmol), anhydrous ethanol (20 mL) and potassium methoxide (4.21 mg, 0.06 mmol) were added to a round-bottom flask, mixed, heated to 120° C. for 4 h, and the reaction was monitored by TLC until the raw material point disappeared. The developing solvent was dichloromethane: petroleum ether = 1:1. The mixture was cooled, precipitated, filtered, washed with anhydrous ethanol, dried over anhydrous MgSO4, and purified by column chromatography. The eluent was dichloromethane: petroleum ether = 1:2 to obtain a product for detecting Hg. 2 + Molecular fluorescent probes.

[0056] Performance Testing

[0057] 1. Take compound A prepared in step (1) of Example 2, compound B prepared in step (2) of Example 2, and the molecular fluorescent probe prepared in step (3) of Example 2, weigh them respectively and calculate their yields. The results are shown in Table 1.

[0058] Table 1 The quality and yield of each product

[0059] product Mass / g Yield / % Compound A 2.01 95.2 Compound B 1.19 90.4 Molecular fluorescent probes 1.32 85.4

[0060] It can be seen from Table 1 that the preparation method has a high yield, a large raw material utilization rate and high economic benefit.

[0061] 2. Take compound A prepared in step (1) of Example 2, compound B prepared in step (2) of Example 2, and the molecular fluorescent probe prepared in step (3) of Example 2, and test them respectively. 1 HNMR spectra and 13 C NMR spectrum, the results are as follows Figure 1-6 shown.

[0062] Depend on Figure 1 It can be seen that 1 H NMR (500MHz, CDCl3) δ7.20-7.11 (m, 2H), 7.06-6.95 (m, 4H), 6.93-6.85 (m, 2H), 4.19 (q, J=7.3Hz, 2H), 1.29 (t, J=7.2Hz, 3H).

[0063] Depend on Figure 2 It can be seen that 13 C NMR (125MHz, CDCl3) δ144.53, 144.52, 135.42, 124.63, 123.32, 115.88, 115.83, 114.61, 114.58, 42.88, 13.50.

[0064] Depend on Figure 3 It can be seen that 1 H NMR (500MHz, CDCl3) δ9.89 (t, J=1.0Hz, 1H), 7.46-7.39 (m, 2H), 7.31 (d, J=8.4Hz, 1H), 7.19 (dd, J=7.5, 1 .7Hz, 1H), 7.07-6.96 (m, 2H), 6.90 (dd, J=7.5, 1.6Hz, 1H), 4.18 (q, J=7.2Hz, 2H), 1.30 (t, J=7.2Hz, 3H).

[0065] Depend on Figure 4 It can be seen that 13 C NMR (125MHz, CDCl3) δ191.90, 144.50, 144.35, 139.02, 135.42, 131.14, 127.23, 124.69, 123.21, 115.61, 115.51, 114.57, 112.35, 42.97, 13.50.

[0066] Depend on Figure 5 It can be seen that 1 H NMR (500MHz, CDCl3) δ8.42 (d, J=0.9Hz, 1H), 7.97 (dd, J=5.9, 3.5Hz, 2H), 7.83 (dd, J=5.8, 3.6Hz, 2H), 7.44 (dd, J=8.4, 2.0Hz, 1H), 7.31 (d, J=8.5Hz, 1H) , 7.23 (dd, J=2.0, 1.0Hz, 1H), 7.17 (dd, J=7.6, 1.5Hz, 1H), 7.06-6.95 (m, 2H ), 6.89 (dd, J=7.7, 1.4Hz, 1H), 4.23 (q, J=7.2Hz, 2H), 1.31 (t, J=7.2Hz, 3H).

[0067] Depend on Figure 6 It can be seen that 13 C NMR (125MHz, CDCl3) δ191.51, 191.21, 144.58, 144.35, 142.43, 136.45, 135.43, 133.03, 130. 92, 130.10, 129.74, 128.16, 124.62, 123.11, 118.22, 115.74, 114.57, 112.24, 42.79, 13.37.

[0068] 3. The molecular fluorescent probe prepared in step (3) of Example 2 was dissolved in EtOH / H2O solvent (1:2, v / v) to prepare 1×10 -5 mol / L molecular fluorescent probe solution, add Hg 2+ , K + , Ca 2+ 、Zn 2+ 、Al 3+ Mg 2+ , Fe 3+ , Mn 2+ 、Ag + 、Cd 2+ , Cu 2+ , Pb 2+ 、Na + The cationic solution (EtOH:H2O=1:2, v / v) was made into a concentration of 10 -5 mol / L, and a cation selectivity test was conducted. The results were as follows Figure 7 shown.

[0069] Depend on Figure 7 It can be seen that the molecular fluorescent probe is sensitive to Hg 2+The detection of Hg is highly specific, and the recognition process is hardly interfered by other metal ions, so it is possible to detect Hg in complex environments. 2+ .

[0070] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting Hg 2+ A molecular fluorescent probe, characterized in that The structural formula is:

2. A method for detecting Hg as claimed in claim 1 2+ A method for preparing a molecular fluorescent probe, characterized in that: The specific steps include: (1) at room temperature, phenoxazine, anhydrous DMSO solution, sodium hydroxide and 1-bromoethane are mixed and stirred for reaction. After the reaction is completed, the reaction solution is quenched with water and extracted with ethyl acetate. The organic phase is separated and dried over anhydrous MgSO4. The solvent is removed and the residue is purified by column chromatography to obtain compound A. (2) Under low temperature conditions, compound A, anhydrous DMF, POCl3 and anhydrous 1,2-dichloroethane are mixed and heated to reflux for reaction. After the reaction is completed, the reaction solution is quenched with 20% NaOH solution, extracted with water and dichloromethane, the organic phase is separated and dried over anhydrous MgSO4, the solvent is removed in vacuo, and the residue is purified by column chromatography to obtain compound B; (3) Compound B, 1,3-indandione, anhydrous ethanol and potassium methoxide are mixed, heated for reaction, and the reaction is monitored by TLC until the raw material point disappears. The mixture is cooled, precipitated, filtered, washed with anhydrous ethanol, dried over anhydrous MgSO4, and purified by column chromatography to obtain the method for detecting Hg. 2+ Molecular fluorescent probes.

3. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (1), the usage ratio of phenoxazine, anhydrous DMSO solution, sodium hydroxide and 1-bromoethane is 0.01 mol: 30 mL: 0.05 mol: 0.02 mol.

4. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (1), the stirring reaction time is 12-24 hours; the eluent used in the column chromatography method is ethyl acetate: petroleum ether = 1:

5.

5. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (2), the usage ratio of compound A, anhydrous DMF, POCl3 and anhydrous 1,2-dichloroethane is 5.5mmol:3mL:5mL:25mL.

6. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (2), the low temperature condition is (-20)-0°C; the temperature of the heating reflux reaction is 50-150°C, and the time is 12-36h; the eluent used in the column chromatography method is ethyl acetate: dichloromethane = 1:

10.

7. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (3), the usage ratio of compound B, 1,3-indandione, anhydrous ethanol and potassium methoxide is 4.2 mmol:5 mmol:20 mL:0.06 mmol.

8. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (3), the heating reaction temperature is 50-120°C and the time is 4-12h.

9. A method for detecting Hg as claimed in claim 2 2+ A method for preparing a molecular fluorescent probe, characterized in that: In step (3), the developing solvent for TLC monitoring is dichloromethane: petroleum ether = 1:1; the eluent used for column chromatography is dichloromethane: petroleum ether = 1:

2.

10. A molecular fluorescent probe as claimed in claim 1 or a molecular fluorescent probe prepared by the preparation method as claimed in any one of claims 2 to 9 for detecting Hg 2+ Application in.

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