A fluorescent probe for detecting Hg 2+ and its synthesis method and application

Abstract

The present invention belongs to the technical field of organic synthesis and analytical chemistry, and specifically relates to a fluorescent probe for detecting Hg<supgt;2+< / supgt>, its synthesis method and application. The chemical name of this fluorescent probe is: (1R,2R)-1,2-bis(2-(4-(1-phenyl-2,2-dioctyloxyphenyl)vinyl)phenoxyacetamido)cyclohexane. This fluorescent probe forms a strong complexation with Hg<supgt;2+< / supgt>, resulting in significant quenching of the fluorescence of the fluorescent probe. The presence of Hg<supgt;2+< / supgt> can be efficiently and selectively detected by the rapid decrease in fluorescence intensity. This property can be used for the sensitive detection of Hg<supgt;2+< / supgt> in water environment, with less interference from other ions. It is an ideal rapid and sensitive sensor for Hg<supgt;2+< / supgt>, and has important practical application value for the detection of samples containing Hg<supgt;2+< / supgt> in actual complex environments.

Description

Technical Field

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

[0002] Hg 2+ is one of the common heavy metal pollutants in the environment, and it is highly toxic to living organisms even at low concentrations. Therefore, developing a technology that can quickly and sensitively detect trace Hg 2+ in the environment is of great significance and practical application value for human health and environmental safety.

[0003] Fluorescent probes are object recognition and detection materials that have received much attention in recent years and are widely used in the detection of metal ions, inorganic anions, organic small molecules, etc. The Chinese invention patent with publication number CN110256331A discloses a fluorescent probe compound for Hg 2+ Due to the special C=N structure of the Schiff base in this compound, its lone pair electrons can complex with positively charged mercury ions to form a larger conjugated plane, resulting in a sharp increase in fluorescence, thereby detecting the presence of mercury ions. This fluorescent material can emit light well in organic solutions, but it is prone to aggregation or become solid in poor solvents such as water, resulting in the disappearance of the fluorescence phenomenon, which limits the practical application of the fluorescent probe in the aqueous phase. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a fluorescent probe for detecting Hg 2+ and its synthesis method and application.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is: a fluorescent probe for detecting Hg 2+ The chemical name of the fluorescent probe is: (1R,2R)-1,2-bis(2-(4-(1-phenyl-2,2-dioctyloxyphenyl)vinyl)phenoxyacetamido)cyclohexane; its chemical structural formula is shown in formula (1):

[0006]

[0007] wherein R is -OC8H 17 .

[0008] Another technical solution adopted by the present invention is: for preparing the above-mentioned fluorescent probe for detecting Hg 2+Preparation method of the fluorescent probe: Add the compound of formula (2), the compound of formula (3), anhydrous potassium carbonate and potassium iodide into a dry acetone system and reflux until the reaction is complete; then add hydrochloric acid solution, stir, extract and separate the organic phase; then distill off the solvent under reduced pressure to obtain a residue. After chromatography of the residue, the compound of formula (1) is obtained;

[0009]

[0010] wherein R is -OC8H 17 .

[0011] Another technical solution adopted by the present invention is: Application of the fluorescent probe for detecting Hg 2+ in the detection of Hg 2+ : Mix the tetrahydrofuran aqueous solution containing the compound of formula (1) with a series of gradient concentration Hg 2+ solutions respectively, measure the corresponding fluorescence intensity, and establish a standard working curve with the fluorescence intensity as the ordinate and the Hg 2+ concentration as the abscissa;

[0012] Mix the tetrahydrofuran aqueous solution containing the compound of formula (1) with the test solution, measure the fluorescence intensity value after mixing, and read out the Hg 2+ concentration in the test solution according to the standard working curve.

[0013] The beneficial effects of the present invention are as follows: The fluorescent probe of the present invention has a "1+2" open-ring structure formed by using tetraphenylethylene as the unit and bridged by cyclohexanediamine. This fluorescent probe forms a strong complexation with Hg 2+ , resulting in significant quenching of the fluorescence of the fluorescent probe. The presence of Hg 2+ can be efficiently and selectively detected through the rapid weakening of the fluorescence intensity. This characteristic can be used for the sensitive detection of Hg 2+ in the water environment, with less interference from other ions, and it is an ideal rapid and sensitive sensor for Hg 2+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the infrared spectrum of the fluorescent probe in Example 1;

[0015] Figure 2 is the 1H nuclear magnetic resonance spectrum of the fluorescent probe in Example 1;

[0016] Figure 3 is the 13C nuclear magnetic resonance spectrum of the fluorescent probe in Example 1;

[0017] Figure 4 is the mass spectrum of the fluorescent probe in Example 1;

[0018] Figure 5For the Hg with gradient concentrations in Example 5 2+ of the fluorescence emission spectrum;

[0019] Figure 6 is the standard working curve in Example 5;

[0020] Figure 7 is the fluorescence emission spectrum of each ion in Example 6;

[0021] Figure 8 is the statistical chart of the interference degree of other ions on the sensitive detection of Hg 2+ ; Specific implementation mode

[0022] In order to illustrate the technical content, the achieved purpose and the effects of the present invention in detail, the following is described in conjunction with the implementation mode and the accompanying drawings.

[0023] A fluorescence probe for detecting Hg 2+ , the chemical name of the fluorescence probe is: (1R,2R)-1,2-bis(2-(4-(1-phenyl-2,2-dioctyloxyphenyl)vinyl)phenoxyacetamido)cyclohexane; its chemical structural formula is shown in Formula (1):

[0024]

[0025] wherein R is -OC8H 17 .

[0026] As can be seen from the above description, the beneficial effects of the present invention are as follows: The fluorescence probe of the present invention has a "1+2" ring-opening structure formed by taking tetraphenylethylene as a unit and bridged by cyclohexanediamine. Among them, tetraphenylethylene is an aggregation-induced emission molecule, and through appropriate modification, it is applicable to fluorescence detection in the aqueous phase; the amide functional group and the oxygen-containing functional group play a coordination role on Hg 2+ , and the cavity surrounded by the functional groups matches the size of Hg 2+ , so that the fluorescence probe has good selectivity for Hg 2+ . The fluorescence probe of the present invention forms a strong complexation with Hg 2+ , resulting in significant quenching of the fluorescence of the fluorescence probe. This characteristic can be used for the sensitive detection of Hg 2+ in the water environment, with less interference from other ions. It is an ideal rapid and sensitive sensor for Hg 2+ , and has important practical application value for the detection of samples containing Hg 2+ in the actual complex environment.

[0027] Another technical solution adopted by the present invention is: for preparing the above-mentioned fluorescence probe for detecting Hg 2+Preparation method of the fluorescent probe: Add the compound of formula (2), the compound of formula (3), anhydrous potassium carbonate and potassium iodide into a dry acetone system and reflux until the reaction is complete; then add hydrochloric acid solution, stir, extract and separate the organic phase; then distill off the solvent under reduced pressure to obtain a residue, and after chromatography of the residue, obtain the compound of formula (1);

[0028]

[0029] wherein R is -OC8H 17 .

[0030] As can be seen from the above description, the synthesis route of the compound of formula (1) is as follows:

[0031]

[0032] wherein R is -OC8H 17 .

[0033] Furthermore, the synthesis route of the compound of formula (2) is as follows:

[0034]

[0035] Furthermore, the synthesis route of the compound of formula (3) is as follows:

[0036]

[0037] wherein R is -OC8H 17 .

[0038] Furthermore, the molar ratio of the compound of formula (2) to the compound of formula (3) is 1:2.5 to 1:1.5.

[0039] As can be seen from the above description, if the molar ratio of the compound of formula (2) to the compound of formula (3) is too high or too low, the yield of the product will be reduced and the separation difficulty of the product will be increased.

[0040] Furthermore, the molar ratio of anhydrous potassium carbonate to the compound of formula (2) is 1:1 to 5:1.

[0041] Furthermore, the molar ratio of potassium iodide to the compound of formula (2) is 1:1 to 5:1.

[0042] Furthermore, the reflux specifically is: reflux for 12 - 48 h under the condition of a temperature of 60 °C.

[0043] As can be seen from the above description, the reflux is stable at a temperature of 60 °C; during the reflux process, if the reflux time is short, the reaction is incomplete; if the reflux time is too long, the reaction energy consumption is increased.

[0044] Furthermore, the eluent used in the chromatography of the residue includes dichloromethane and n - hexane.

[0045] As can be seen from the above description, the fluorescence probe of the present invention has high solubility in dichloromethane and n-hexane.

[0046] Another technical solution adopted by the present invention is as follows: the application of the fluorescence probe for detecting Hg 2+ when detecting Hg 2+ is to mix the tetrahydrofuran aqueous solution containing the compound of formula (1) with Hg 2+ solutions with a series of gradient concentrations respectively, measure the corresponding fluorescence intensities, and establish a standard working curve with the fluorescence intensity as the ordinate and the Hg 2+ concentration as the abscissa;

[0047] Mix the tetrahydrofuran aqueous solution containing the compound of formula (1) with the test solution, measure the fluorescence intensity value after mixing, and read out the Hg 2+ concentration in the test solution according to the standard working curve.

[0048] As can be seen from the above description, first establish a standard working curve with the fluorescence intensity as the ordinate and the Hg 2+ concentration as the abscissa, and then read out the Hg 2+ concentration in the test solution according to the standard working curve. This detection method is efficient, reasonable, and highly specific.

[0049] Furthermore, the volume ratio of tetrahydrofuran to water in the tetrahydrofuran aqueous solution is 5:97 to 5:93.

[0050] Furthermore, when measuring the fluorescence intensity, the detection wavelength is 470 - 490 nm.

[0051] As can be seen from the above description, the fluorescence probe compound prepared by the present invention has strong blue-green fluorescence emission at a detection wavelength of 470 - 490 nm in a tetrahydrofuran-water (5:97 - 5:93) solution. The fluorescence intensity is increased by nearly 40 times compared with that in the tetrahydrofuran solution. Under this condition, the detection effect is obvious, the sensitivity is high, and it can be used for the sensitive detection of Hg 2+ in the water environment.

[0052] Example 1 of the present invention is: a fluorescence probe for detecting Hg 2+ The chemical name of the fluorescence probe is: (1R,2R)-1,2-bis(2-(4-(1-phenyl-2,2-dioctyloxyphenyl)vinyl)phenoxyacetamido)cyclohexane; the molecular formula is: C 94 H 118 N2O8; its chemical structural formula is shown in formula (1):

[0053]

[0054] where R is -OC8H17 .

[0055] The infrared spectrum of the fluorescent probe is shown in Figure 1 , infrared spectrum (KBr), v / cm -1 : 3417 (N-H), 1668 (C=O). The 1H NMR spectrum is shown in Figure 2 , 1H NMR (400 MHz, CDCl3), δ, ppm: 6.85 - 7.15 (m, 24H, ArH and NH), 6.58 - 6.64 (m, 12H, ArH), 4.33 (dd, 4H, OCH2CO), 3.85 (t, J = 8.0 Hz, 8H, OCH2), 3.75 (bs, 2H, CH), 1.25 - 2.07 (m, 56H, CH2), 0.88 (t, J = 8.0 Hz, 12H, CH3); The 13C NMR spectrum is shown in Figure 3 , 13C NMR (100 MHz, CDCl3), δ, ppm: 171.33, 158.04, 157.60, 155.29, 144.38, 139.85, 138.20, 138.04, 136.18, 132.71, 132.51, 131.36, 127.67, 126.00, 113.85, 113.55, 113.34, 67.79, 66.95, 53.02, 45.18, 32.20, 31.81, 29.70, 29.38, 29.37, 26.08, 24.64, 22.66, 14.12; The mass spectrum is shown in Figure 4 , high-resolution mass spectrum (m / s): calculated value for C 94 H 118 N2O8: 1402.889, measured value is 1402.889 [M] + .

[0056] Example 2 of the present invention is: the preparation method of the fluorescent probe in Example 1, characterized in that,

[0057]

[0058] wherein R is -OC8H 17 ;

[0059] S1: Synthesize the compound of formula (2), and the synthetic route is:

[0060]

[0061] S2: Synthesize the compound of formula (3), and the synthetic route is:

[0062]

[0063] wherein R is -OC8H 17 ;

[0064] References for the synthesis methods of the compound of formula (2) and the compound of formula (3): Zhang, X.; Jiang, S.; Lin, G.; Guo, H.; Yang, F. Novel fluorescent columnar liquid crystal based on tetraphenylethylene-rufigallol-tetraphenylethylene triads, Journal of Molecular Structure, 2022, 1252, 132210.

[0065] S3: Under nitrogen protection, in a 250 mL three-necked flask, add 1.0 mmol of the compound of formula (2), 1.5 mmol of the compound of formula (3), 1.0 mmol of anhydrous potassium carbonate and 1.0 mmol of potassium iodide to a dry acetone system and reflux at 60 °C for 48 h until the reaction is complete, while monitoring the reaction progress by thin-layer chromatography; after the raw materials are completely reacted, add 30 mL of 1 mol / L hydrochloric acid solution to the reaction mixture and stir well. After stirring, extract with 30 mL of chloroform, separate the organic phase; then evaporate the solvent under reduced pressure to obtain a residue, and separate the product by silica gel column chromatography (eluent volume ratio: dichloromethane / n-hexane = 1 / 3) to obtain the compound of formula (1) with a yield of 54%;

[0066] The synthesis route of the compound of formula (1) is:

[0067]

[0068] wherein R is -OC8H 17 ;

[0069] Example 3 of the present invention is:

[0070] The difference between Example 3 and Example 2 is only in S3: Under nitrogen protection, in a 250 mL three-necked flask, add 2.0 mmol of the compound of formula (2), 4 mmol of the compound of formula (3), 4.0 mmol of anhydrous potassium carbonate and 4.0 mmol of potassium iodide to a dry acetone system and reflux at 60 °C for 24 h until the reaction is complete, while monitoring the reaction progress by thin-layer chromatography; after the raw materials are completely reacted, add 60 mL of 1 mol / L hydrochloric acid solution to the reaction mixture and stir well. After stirring, extract with 50 mL of chloroform, separate the organic phase; then evaporate the solvent under reduced pressure to obtain a residue, and separate the product by silica gel column chromatography (eluent volume ratio: dichloromethane / n-hexane = 1 / 3) to obtain the compound of formula (1) with a yield of 84%.

[0071] Example 4 of the present invention is as follows:

[0072] The difference between Example 4 and Example 2 is only that: S3: Under nitrogen protection, in a 250 mL three-necked flask, 1.0 mmol of the compound of formula (2), 2.5 mmol of the compound of formula (3), 5.0 mmol of anhydrous potassium carbonate and 5.0 mmol of potassium iodide were added to a dry acetone system and refluxed at 60 °C for 10 h until the reaction was complete, while monitoring the reaction progress by thin-layer chromatography; after the raw materials were completely reacted, 35 mL of 1 mol / L hydrochloric acid solution was added dropwise to the reaction mixture and stirred well. After stirring, it was extracted with 35 mL of chloroform, and the organic phase was separated; then the solvent was distilled off under reduced pressure to obtain a residue, and the residue was separated by silica gel column chromatography (eluent volume ratio: dichloromethane / n-hexane = 1 / 3) to obtain the compound of formula (1) with a yield of 76%.

[0073] Example 5 of the present invention is: The application of the fluorescent probe of Example 1 in detecting Hg 2+ is as follows:

[0074] S1: An aqueous solution of tetrahydrofuran (volume ratio of tetrahydrofuran to water is 5:95) containing 1×10 -5 mol / L of the fluorescent probe was mixed with a series of gradient concentrations of Hg 2+ solutions respectively to measure the corresponding fluorescence intensities. The detection results are shown in Figure 5 ,, Figure 5 The Hg 2+ concentration increases successively from top to bottom in the curve, and the Hg 2+ concentrations are 0, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.4, 1.5, 1.6, 1.8, 2.0, 4.0 times that of the fluorescent probe respectively. The detection wavelength is 480 nm;

[0075] S2: Based on the detection results of S1, a standard working curve with fluorescence intensity as the ordinate and Hg 2+ concentration as the abscissa was established. This standard working curve is shown in Figure 6 ; It can be seen from Figure 5 and Figure 6 that there is a good linear relationship between the fluorescence intensity and the equivalent concentration of Hg 2+ in this detection method.

[0076] S3: An aqueous solution of tetrahydrofuran (volume ratio of tetrahydrofuran to water is 5:95) containing 1×10 -5 mol / L of the fluorescent probe was mixed with the test solution, and the fluorescence intensity value after mixing was measured. The Hg 2+ concentration in the test solution was read according to the standard working curve.

[0077] Example 6 of the present invention is as follows: Add the fluorescent probe in Example 1 at a concentration of 1×10 -5 mol / L to an aqueous solution of tetrahydrofuran (the volume ratio of tetrahydrofuran to water is 5:95), and then add various ions at a concentration of 1×10 -5 mol / L (blank, Li + , Na + , k + , NH 4+ , Mg 2+ , Ca 2+ , Ba 2+ , Al 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Hg 2+ , Co 2+ , Pd 2+ , La 3+ , Cl - , NO 3- , HPO4 2- , and PO4 3- ) for fluorescence detection. The detection results are shown in Figure 7 . As can be seen from Figure 7 , the fluorescent probe in Example 1 has good selective detection ability for Hg 2+ .

[0078] Example 7 of the present invention is as follows: Add 1×10 -5 mol / L Hg 2+ and 1×10 -5 mol / L of the fluorescent probe in Example 1 to an aqueous solution of tetrahydrofuran (the volume ratio of tetrahydrofuran to water is 5:95), and then add various metal ions at a concentration of 1×10 -5 mol / L (blank, Li + , Na + , k + , NH 4+ , Mg 2+ , Ca 2+ , Ba 2+ , Al 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+, Hg 2+ , Co 2+ , Pd 2+ , La 3+ , Cl - , NO 3- , HPO4 2- and PO4 3- ) for fluorescence detection. The detection results are summarized with those in Example 6. Taking the ratio of the maximum fluorescence intensity (I) of the mixed solution to the maximum fluorescence intensity (I0) of the same-concentration solution containing only the fluorescent probe as the ordinate, a statistical chart of the interference degree of other metal ions on the sensitive detection of Hg 2+ is plotted. The statistical results are shown in Figure 8 , where SDS is the fluorescent probe in Example 1.

[0079] It can be seen from Figure 8 that when other metal ions are added, the I / I0 ratio is close to 1, indicating that other ions have little effect on the fluorescence of the fluorescent probe. However, when the fluorescent probe is added with other ions and then Hg 2+ is added, the fluorescence is greatly weakened, which indicates that other ions have little interference on the sensitive detection of Pd 2+ .

[0080] In summary, the fluorescent probe of the present invention has a "1 + 2" open-loop structure formed by using tetraphenylethylene as a unit and through the bridging action of cyclohexanediamine. This structure enables the fluorescent probe to form a strong complexation with Hg 2+ , resulting in strong blue-green fluorescence emission of the fluorescent probe at the detection wavelength of 470 - 490 nm, which can be significantly quenched, and with little interference from other ions. It is suitable for the sensitive detection of Hg 2+ in water environment and has important practical application value for the detection of samples containing Hg 2+ in actual complex environments.

[0081] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A fluorescent probe for detecting Hg 2+ , characterized in that The chemical name of the fluorescent probe is: (1R,2R)-1,2-bis(2-(4-(1-phenyl-2,2-dioctyloxyphenyl)vinyl)phenoxyacetamido)cyclohexane; its chemical structural formula is shown in Formula (1): wherein R is -OC8H 17 .

2. A method for preparing the fluorescent probe for detecting Hg as described in claim 1 2+ , characterized in that Add the compound of Formula (2), the compound of Formula (3), anhydrous potassium carbonate and potassium iodide into a dry acetone system and reflux until the reaction is complete; then add hydrochloric acid solution, stir, extract and separate the organic phase; Then distill off the solvent under reduced pressure to obtain a residue. After chromatography of the residue, the compound of Formula (1) is obtained; wherein R is -OC8H 17 .

3. The preparation method of the fluorescent probe for detecting Hg 2+ , characterized in that The molar ratio of the compound of Formula (2) to the compound of Formula (3) is 1:2.5 to 1:1.

5.

4. The preparation method of the fluorescent probe for detecting Hg 2+ , characterized in that The molar ratio of the anhydrous potassium carbonate to the compound of Formula (2) is 1:1 to 5:

1.

5. The preparation method of the fluorescent probe for detecting Hg 2+ , characterized in that The molar ratio of the potassium iodide to the compound of Formula (2) is 1:1 to 5:

1.

6. The preparation method of the fluorescent probe for detecting Hg 2+ , characterized in that The specific reflux is: reflux at a temperature of 60 °C for 12 to 48 h.

7. The preparation method of the fluorescent probe for detecting Hg 2+ is characterized in that The eluent used in the chromatography of the residue includes dichloromethane and n-hexane.

8. The application of the fluorescent probe for detecting Hg 2+ in the detection of Hg 2+ , characterized in that The tetrahydrofuran aqueous solution containing the compound of formula (1) was respectively mixed with a series of gradient concentration Hg 2+ solutions, and the corresponding fluorescence intensities were measured to establish a standard working curve with the fluorescence intensity as the ordinate and the Hg 2+ concentration as the abscissa; Mix an aqueous solution of the compound of formula (1) in tetrahydrofuran with the solution to be tested, measure the fluorescence intensity value after mixing, and read out the Hg concentration in the solution to be tested according to the standard working curve. 2+ Concentration.

9. The fluorescence probe for detecting Hg according to claim 8 2+ in the detection of Hg 2+ , characterized in that The volume ratio of tetrahydrofuran to water in the aqueous solution of tetrahydrofuran is 5:97 to 5:

93.

10. Use of the fluorescent probe for detecting Hg 2+ in the detection of Hg 2+ , characterized in that When measuring the fluorescence intensity, the detection wavelength is 470 to 490 nm.

Images