Preparation method and application of water-soluble fluorescent probe for detecting mercury ions

Abstract

The invention discloses a preparation method and application of a water-soluble fluorescent probe for detecting mercury ions, and relates to the field of analysis and detection of mercury ions, in particular to a preparation method of a water-soluble 1, 8-naphthalimide fluorescent probe C and detection of mercury ions. The method overcomes the defects that in an existing mercury ion fluorescent probe detection method, a test system needs assistance of an organic solvent, and green detection cannot be achieved in an all-water environment. The preparation method of the fluorescent probe C comprises the following step: carrying out reflux reaction on 4-bromine-N-2-(2-(2-hydroxyethoxy) ethoxy) ethyl-1, 8-naphthalimide and hydrazine hydrate in ethanol to obtain the fluorescent probe C. The fluorescent probe C disclosed by the invention is a fluorescent probe. The fluorescent probe C prepared by the invention can realize specific fluorescence'off-on 'detection on mercury ions in a full-water-based HEPES buffer solution with the pH value of 7.4, the detection time is short, and the interference of various ions can be resisted. The prepared fluorescent probe can be used for trace detection of mercury ions in a water body.

Description

Technical Field

[0001] The present invention relates to the field of mercury ion analysis and detection, and in particular to a method for preparing a water-soluble 1,8-naphthaleneimide fluorescent probe and an application thereof in mercury ion detection. Background Art

[0002] Mercury ion (Hg 2+ ) has important applications in the electronics industry, chemical industry, medical industry, lighting and optical industries. Although mercury ions are widely used, their toxicity cannot be ignored. Excessive exposure to mercury ions can cause serious harm to human health and the environment. Mercury ions released from industrial activities, coal burning, and waste incineration enter the atmosphere and water bodies, and are then accumulated and enriched by organisms. Due to their stability and difficulty in degrading, mercury ions are persistent in ecosystems and pose potential hazards to organisms, including damage to the nervous system, impaired immune system, effects on the reproductive system, and damage to the cardiovascular and renal systems. Especially for fetuses and infants, exposure to mercury ions may lead to intellectual retardation and behavioral problems. Therefore, it is particularly important to strengthen the monitoring and management of mercury ion pollution.

[0003] Methods for detecting mercury ions include electrochemical method, chromatography and fluorescent probe method. Among them, electrochemical method and chromatography have high requirements for sample processing and long detection time, which limits their wide application. The fluorescent probe method has attracted much attention due to its high sensitivity, rapid response and good selectivity. However, most of the reported mercury ion fluorescent probes usually require the use of organic solvents for detection, which may have adverse effects on the environment, limiting their sustainability and environmental friendliness in practical applications. Therefore, the development of fluorescent probes that can detect mercury ions under pure water conditions is an important direction of current research. Pure water fluorescent probes can not only reduce dependence on organic solvents, but also significantly reduce environmental impact, which meets the requirements of sustainable development. However, to achieve this goal, it is necessary to overcome challenges such as fluorescence signal stability, detection sensitivity and anti-interference ability under pure water conditions, which requires further research.

[0004] 1,8-Naphthalimide is one of the most commonly used fluorophores in the synthesis of fluorescent probes. It not only has good chemical and optical stability, but also has good biocompatibility. In addition, the large Stokes shift and easy modification of 1,8-naphthalimide fluorescent probes are also important advantages. By adjusting the substituents connected to the nitrogen atom of the 1,8-naphthalimide fragment and the 4,5 or 3,4 positions of the naphthalene ring part, it has good compatibility and specificity, and is widely used in the field of fluorescent probe preparation. In the present invention, by introducing a long-chain group rich in oxygen atoms into the nitrogen atom of the 4-bromo-1,8-naphthalimide fragment, the hydrophilicity of the probe is increased on the one hand, and the complexation site is constructed on the other hand. In addition, a hydrazine group is introduced at the 4 position of the naphthalene ring part to replace the bromine atom, which further improves the water solubility of the probe. Based on the above ideas, a 1,8-naphthalimide fluorescent probe C is designed and prepared, which can realize the fluorescence "off-on" detection of mercury ions in pure water. The detection process has the advantages of good specificity, strong anti-interference, rapid response and low detection limit, and has good application prospects in the field of environmental monitoring. Summary of the invention

[0005] The present invention aims to solve the problem that the detection system of the existing mercury ion fluorescent probe detection method needs the assistance of organic solvent, and provides a method for preparing a fluorescent probe for detecting mercury ions in a pure water system and its application.

[0006] The molecular structure of the water-soluble fluorescent probe C used to detect mercury ions in the present invention is:

[0007]

[0008] The synthetic route of the fluorescent probe C is as follows:

[0009]

[0010] The preparation method of the fluorescent probe C is as follows: 4-bromo-N-2-(2-(2-hydroxyethoxy)ethoxy)ethyl-1,8-naphthalimide and 80w% hydrazine hydrate are refluxed in anhydrous ethanol to obtain the fluorescent probe C.

[0011] Application of the fluorescent probe C of the present invention in the quantitative and qualitative detection of mercury ions.

[0012] Furthermore, the fluorescent probe C can realize the fluorescence "off-on" detection of mercury ions in pure water.

[0013] Furthermore, when the mercury ion concentration is in the range of 1-11 μM, the fluorescence intensity of the fluorescent probe C is linearly related to the mercury ion concentration, and the linear equation is y=184.04x-63.56, R 2 =0.990, the detection limit of mercury ions is calculated to be 4.53×10 - 8 mol / L.

[0014] Furthermore, the response time of fluorescent probe C to mercury ions is 12 seconds.

[0015] Furthermore, fluorescent probe C can detect mercury ions in tap water, and the recovery rate of mercury ions in actual water samples is 98.10% to 100.39%, with a relative standard deviation of 0.17 to 1.16%.

[0016] Principle of the present invention:

[0017] The fluorescent probe C prepared by the present invention does not show fluorescence itself. When the fluorescent probe C acts on mercury ions, the mercury ions are complexed with the carbonyl group and the ether bond oxygen atom in the probe molecule, so that the original photoinduced electron transfer effect is weakened, thereby enhancing the fluorescence effect of the system, and finally realizing the detection of mercury ions.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The fluorescent probe C prepared by the present invention can realize the fluorescence detection of mercury ions in pure water, and the detection process does not require the assistance of organic solvents, making the fluorescent probe detection method more green and environmentally friendly.

[0020] 2) The response time of the fluorescent probe C prepared by the present invention to mercury ions is only 12 seconds, the detection speed is fast, and the detection efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention prepares the fluorescent probe C 1 H NMR spectrum;

[0022] Figure 2 The FT-RT spectrum of the fluorescent probe C prepared by the present invention;

[0023] Figure 3 Selective recognition diagram of fluorescent probe C for metal ions;

[0024] Figure 4 The effect of coexisting metal ions on the recognition of mercury ions by fluorescent probe C;

[0025] Figure 5 The effect of coexisting anions on the recognition of mercury ions by fluorescent probe C;

[0026] Figure 6 Linear relationship diagram of fluorescence response of fluorescent probe C to different concentrations of mercury ions;

[0027] Figure 7 Job's plot of fluorescent probe C to mercury ions;

[0028] Figure 8Response time diagram of fluorescent probe C to mercury ions; DETAILED DESCRIPTION

[0029] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0030] Specific implementation method 1: This implementation method is a water-soluble fluorescent probe for detecting mercury ions. The molecular structure of the fluorescent probe C is:

[0031]

[0032] Specific implementation method 2: The preparation method of the fluorescent probe C is as follows: 4-bromo-N-2-(2-(2-hydroxyethoxy)ethoxy)ethyl-1,8-naphthalimide and 80w% hydrazine hydrate are refluxed in anhydrous ethanol.

[0033] Specific implementation method three: Application of the fluorescent probe C in the present implementation method in the detection of mercury ions.

[0034] Specific embodiment 4: This embodiment is different from specific embodiment 3 in that the fluorescent probe C can realize the fluorescence "off-on" detection of mercury ions. The rest is the same as specific embodiment 3.

[0035] Specific embodiment 5: This embodiment is different from specific embodiment 3 or 4 in that: when the mercury ion concentration is in the range of 1-11 μM, the fluorescence intensity of the fluorescent probe C is linearly related to the mercury ion concentration, and the linear equation is y=184.04x-63.56, R 2 =0.990, the detection limit of mercury ions is calculated to be 4.53×10 -8 mol / L. The rest is the same as the third or fourth embodiment.

[0036] Specific embodiment 6: This embodiment is different from specific embodiments 3 to 5 in that the response time of the fluorescent probe C to mercury ions is 12 seconds. The rest is the same as specific embodiments 3 to 5.

[0037] Specific embodiment 7: This embodiment is different from specific embodiments 3 to 6 in that the fluorescent probe C can detect mercury ions in tap water, and the recovery rate of mercury ions in actual water samples is 98.10% to 100.39%, and the relative standard deviation is 0.17 to 1.16%. Other aspects are the same as specific embodiments 3 to 6.

[0038] When actually testing samples containing mercury ions, the samples can be pre-treated by centrifugation and filtration to remove solid particle impurities.

[0039] The embodiments of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation plans and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0040] Example 1: The preparation method of the fluorescent probe C in this example is carried out according to the following steps:

[0041] 4-Bromo-N-2-(2-(2-hydroxyethoxy)ethoxy)ethyl-1,8-naphthalimide (0.3000 g, 0.73 mmol), 80% hydrazine hydrate (0.0736 g, 1.5 mmol) and 10 mL of anhydrous ethanol were added to a 25 mL three-necked flask, and the reaction was stirred at 80 ° C. reflux until completion; after cooling to room temperature, vacuum filtration and drying, and washing with ethanol to obtain red 1,8-naphthalimide fluorescent probe C (0.2129 g) with a yield of 78.3%. 1 H NMR (300 MHz, DMSO-d 6 )δ9.11(s,1H),8.60(d,J=8.4Hz,1H),8.40(d,J=6.4Hz,1H),8.28(d,J=8.6Hz,1H),7.62(dd,J=9. 0,1.2Hz,1H),7.24(d,J=8.7Hz,1H),4.67(s,2H),4.54(t,J=5.3Hz,1H),4.20(t,J=6.5Hz,2H),3.6 1(t,J=6.6Hz,2H),3.57–3.54(m,2H),3.50–3.46(m,2H),3.41(t,J=3.0Hz,2H),3.38–3.36(m,2H) .IR(KBr)ν:3346,2897,2869,1687,1631,1571,1535,1395,1361,1141,1118,1071,898,773,582cm -1 .

[0042] 1,8-Naphthalimide Fluorescent Probe C 1 H NMR spectra, FT-RT spectra such as Figure 1 , 2 shown.

[0043] Example 2: Preparation of fluorescent probe C solution, according to the following steps:

[0044] Accurately weigh 3.6 mg of 1,8-naphthalimide fluorescent probe C and prepare it with methanol to 1.0×10 -2 mol / L mother solution A; take 50μL of the concentration of 1.0×10 -2mol / L solution A was diluted to 50 mL with HEPES buffer solution at pH 7.4 to obtain 1.0×10 -5 mol / L fluorescent probe C solution.

[0045] Example 3: Selective recognition of metal ions by fluorescent probe C is carried out according to the following steps:

[0046] Take 3 mL of fluorescent probe C solution and add 3 eq. of Cu 2+ ,Ba 2+ ,Bi 2+ ,Hg 2+ ,Ca 2+ ,Cd 2+ ,Cr 3+ ,Co 2+ ,K + ,Li 2+ ,Al 3+ Mg 2+ ,Na + ,Ni 2+ ,Pb 2+ ,Cs 2+ ,Ce 3+ ,Fe 3+ ,Zn 2+ ,Ag + The fluorescence intensity of the aqueous solution was measured at an excitation wavelength of 351 nm. Figure 3 As shown. After adding mercury ions, the fluorescence of the system is significantly enhanced. The addition of copper ions also increases the fluorescence intensity of the system, but the fluorescence enhancement effect is far less than that of mercury ions. When other metal ions are added, the fluorescence intensity does not change significantly, indicating that the fluorescent probe C solution can achieve specific recognition of mercury ions.

[0047] Example 4: The anti-interference ability of fluorescent probe C to recognize mercury ions is carried out according to the following steps:

[0048] 3 eq. of Cu was added to the fluorescent probe C solution. 2+ ,Ba 2+ ,Bi 2+ ,Ca 2+ ,Cd 3+ ,Cr 3+ ,Co 3+ ,K + ,Li 2+ ,Al 3+ Mg 2+ ,Na + ,Ni 2+ ,Pb 2+ ,Cs 2+ ,Ce 3+ ,Fe 3+,Zn 2+ ,Ag + and anion S 2 O 3 2- 、SO 4 2- 、SO 3 2- 、F - ,PO 4 3- 、NO 3 - ,I-,CO 3 2- 、CN-、CH 3 COO - Cr 2 O 7 2- and P 2 O 7 4- The fluorescence intensity of the aqueous solution was recorded at an excitation wavelength of 351 nm, and then 3 eq. of Hg 2+ aqueous solution, observe and record the changes in fluorescence intensity. Figure 4 , 5 The presence of other metal ions or anions except copper ions will not change the fluorescence of the probe itself. Only copper ions can slightly enhance the fluorescence of the system. However, the presence of EDTA can 2+ The effect of was masked, and the fluorescence was significantly enhanced by adding mercury ions in each system. Therefore, fluorescent probe C has good anti-interference ability for the detection of mercury ions.

[0049] Example 5: The detection limit of the fluorescent probe C for mercury ions is carried out according to the following steps:

[0050] Take 3mL of the solution with a concentration of 1.0×10 -5 mol / L fluorescent probe C solution, and then add 3 μL of 1×10 -3 mol / L mercury ion aqueous solution, and measure the fluorescence intensity. The results are as follows Figure 6 As shown. When the mercury ion concentration is within 0μM-15μM, the fluorescence intensity increases with the increase of mercury ion concentration. In addition, within 1μM-11μM, the fluorescence intensity of probe C shows a good linear relationship with the mercury ion concentration, and the fitting equation is y=184.04x-63.56, R 2 =0.990. According to the calculation formula of detection limit 3σ / k, the detection limit of fluorescent probe C for mercury ions is calculated to be 4.53×10 -8 mol / L, indicating that fluorescent probe C can realize trace detection of mercury ions and has good detection sensitivity.

[0051] Example 6: The interaction between fluorescent probe C and mercury ions is carried out according to the following steps:

[0052] Keep the total concentration of fluorescent probe C and mercury ions in the detection system at 1×10 -5 mol / L remains unchanged. By changing the equivalent ratio of fluorescent probe C and mercury ions, the fluorescence intensity is measured respectively and the Job's Plot curve is drawn. The results are shown in Figure 7 When the molar fraction of mercury ions is 0.48, the fluorescence intensity has an inflection point, which indicates that the interaction ratio between fluorescent probe C and mercury ions is 1:1.

[0053] Example 7: The response time of fluorescent probe C to mercury ions is carried out according to the following steps:

[0054] Take 3mL of the solution with a concentration of 1.0×10 -5 mol / L fluorescent probe C solution, add 1 equivalent concentration of 1×10 -2 mol / L mercury ion aqueous solution, measure the fluorescence intensity every three seconds, and record the results as follows Figure 8 As shown in Figure 2, after the addition of mercury ions, the fluorescence intensity of the system increased rapidly within the first 6 seconds and stabilized at about 12 seconds. This shows that probe C can quickly recognize mercury ions.

[0055] Example 8: Application of fluorescent probe C in detecting mercury ions in actual water samples

[0056] In order to investigate the potential application of fluorescent probe C in the actual environment, laboratory tap water was selected and the water samples were pretreated: the water samples were centrifuged at a speed of 12000rpm for 10min, filtered with a 0.45μm filter, and mercury ion solutions with concentrations of 4μmol / L, 6μmol / L, 8μmol / L, and 10μmol / L were prepared. The above mercury ion solutions of different concentrations were added to the fluorescent probe C solution, and the fluorescence emission peak intensity value of the fluorescent probe at 400nm was measured at an excitation wavelength of 351nm, and it was substituted into the following equation to calculate the concentration of the mercury ion solution to be tested. The test results are shown in Table 1.

[0057] y=184.04x-63.56

[0058] Wherein, X is the mercury ion concentration and Y is the fluorescence emission peak intensity value.

[0059] Table 1 Detection of mercury ions by fluorescent probe C in actual water samples

[0060] Actual water sample Addition amount (μmol / L) Detection amount (μmol / L) Recovery rate (%) RSD(%) blank / / / 1.60 1(tap water) 4 3.92 98.10 0.27 2 (tap water) 6 6.02 100.39 1.16 3(Tap water) 8 7.97 99.61 0.38 4 (tap water) 10 9.96 99.57 0.17

[0061] It can be seen from Table 1 that the recovery rate of mercury ions in actual water samples is 98.10% to 100.39%, and the relative standard deviation is 0.17 to 1.16%. The measured mercury ion concentration has a small error with the corresponding spiked concentration. These results show that the fluorescent probe C prepared by the present invention has good accuracy in detecting mercury ions in actual water samples, can quantitatively detect mercury ions in the range of 1 to 11 μmol / L, and has good practical performance.

Claims

1. A water-soluble fluorescent probe for detecting mercury ions, characterized in that The molecular structure of fluorescent probe C is:

2. A water-soluble fluorescent probe for detecting mercury ions according to claim 1, characterized in that The preparation method of probe C is as follows: 4-bromo-N-2-(2-(2-hydroxyethoxy)ethoxy)ethyl-1,8-naphthalimide and 80w% hydrazine hydrate are refluxed in ethanol.

3. Use of the fluorescent probe C as described in claim 1 in the quantitative and qualitative detection of mercury ions.

4. The use according to claim 3, characterized in that Fluorescent probe C can realize fluorescent "off-on" detection of mercury ions in a pure water environment.

5. The use according to claim 3, characterized in that When the mercury ion concentration is in the range of 1-11 μM, the fluorescence intensity of fluorescent probe C is linearly related to the mercury ion concentration, and the linear equation is y=184.04x-63.56, R 2 =0.990, the detection limit of mercury ions is calculated to be 4.53×10 -8 mol / L.

6. The use according to claim 3, characterized in that The response time of fluorescent probe C to mercury ions is 12 seconds.

7. The use according to claim 3, characterized in that Fluorescent probe C can detect mercury ions in tap water. The recovery rate of mercury ions in actual water samples is 98.10% to 100.39%, and the relative standard deviation is 0.17 to 1.16%.

Images