A lithium-ion fluorescent probe, its preparation method and application

Abstract

This invention provides a lithium-ion fluorescent probe, its preparation method, and its application, belonging to the field of analytical detection technology. The lithium-ion fluorescent probe provided by this invention has an emitting group with emission wavelengths in the visible and near-infrared regions and a high fluorescence quantum yield, and possesses a crown ether recognition site. This site serves as a highly selective response site for lithium ions, exhibiting a specific response to lithium ions. Therefore, the fluorescence signal changes significantly before and after the probe molecule binds to lithium ions, thereby achieving the purpose of quantitative detection of lithium ions. Furthermore, this fluorescent probe molecule exhibits high selectivity and sensitivity to lithium ions.

Description

Technical Field

[0001] This invention relates to the field of analytical detection technology, and in particular to a lithium-ion fluorescent probe, its preparation method, and its application. Background Technology

[0002] Lithium is an important resource and an indispensable raw material for modern high-tech products. With the rapid development of new energy vehicles, electronic devices, and energy storage technologies, the application of lithium in the field of new energy materials has received significant attention, especially given the current trend of electric vehicles replacing gasoline vehicles, which is essentially a process of metallic lithium replacing petroleum. In catalysis, lithium is widely used in the catalytic processes of hydrogenation and cracking reactions in biological and chemical fields. In the medical field, lithium has the function of improving hematopoiesis, is an effective sedative, and can calm the nerves and control nervous disorders. Lithium can also be used for the prevention of cardiovascular diseases, has a protective effect on biological membranes, and can increase the stability of membrane structures.

[0003] my country boasts abundant lithium resources, ranking second in the world, particularly in the western Qaidam Basin and northeastern Sichuan Basin, where brine composition is excellent and lithium reserves are substantial, possessing immense development and application value. Solvent extraction offers advantages such as high efficiency, continuous operation, simple operation, and low fixed costs, leading to its rapid development in lithium extraction from high magnesium-to-lithium ratio salt lake brines. Xinghua Lithium Salt has established a lithium carbonate production line using extraction to extract lithium from the Da Qaidam Salt Lake, and is continuing to expand its capacity. Real-time monitoring of lithium ion concentration during each extraction stage is crucial for controlling production costs and efficiency. However, the complex coexisting ions in the brine during the later stages of evaporation and concentration, along with significant variations in ion concentration at each concentration and separation stage, pose considerable challenges to lithium concentration analysis. Currently, numerous methods exist for the analysis and determination of trace lithium both domestically and internationally, including atomic emission spectrometry, atomic absorption spectrometry, ion chromatography, flow injection potentiometric titration, capillary electrophoresis, and mass spectrometry. However, the commonly used detection methods for trace lithium analysis in brine systems are atomic emission spectrometry, atomic absorption spectrometry, ion chromatography, and flow injection potentiometric titration. Flame atomic emission spectrometry is the most classic lithium analysis method. Its advantages are high accuracy and low sample consumption. However, its disadvantages include severe matrix interference when determining lithium content in brine, and the cumbersome and inconvenient matrix matching method. Calcium, strontium, magnesium, sodium, and the interaction between calcium and boron in the system all have a significant impact on the analysis of lithium ion concentration.

[0004] Fluorescence detection, with its high sensitivity and simplicity, has become an important and powerful method for detecting trace samples, attracting increasing attention in recent years. Therefore, researching novel fluorescent probes and realizing their application in lithium-ion detection remains of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a lithium-ion fluorescent probe, its preparation method, and its application, so as to achieve efficient and rapid detection of lithium-ion concentration.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a lithium-ion fluorescent probe having the structure shown in Formula 1:

[0008]

[0009] This invention provides a method for preparing the lithium-ion fluorescent probe described in the above technical solution, comprising the following steps:

[0010] N-hexa-12-crown-4,4-bromo-1,8-naphthalenedicarboxylic anhydride and ethylene glycol monomethyl ether were mixed and subjected to the first reaction to give the first compound;

[0011] The first compound, ethylenediamine, and DMF were mixed to carry out a second reaction, yielding a second compound;

[0012] Diethylene glycol monomethyl ether, sodium hydroxide, tetrahydrofuran, p-toluenesulfonyl chloride and water were mixed and subjected to a third reaction to obtain a third compound;

[0013] The second compound, the third compound, and THF were mixed and subjected to a fourth reaction to obtain a lithium-ion fluorescent probe.

[0014] Preferably, the molar ratio of N-hexa-12-crown-4 to 4-bromo-1,8-naphthalenedicarboxylic anhydride is 0.5–2:0.5–2; and the reaction time is 3–5 h.

[0015] Preferably, the mass ratio of the first compound to ethylenediamine is (3.5–4):1; and the reaction time is 10–15 h.

[0016] Preferably, the molar ratio of diethylene glycol monomethyl ether, sodium hydroxide, and p-toluenesulfonyl chloride is 40–60:170–180:50–70; the third reaction is carried out at room temperature for 12–16 hours.

[0017] Preferably, the molar ratio of the second compound to the third compound is 0.1:0.15 to 0.3.

[0018] Preferably, the fourth reaction is carried out at room temperature for 4 to 6 hours.

[0019] This invention provides the application of the lithium-ion fluorescent probe described in the above technical solution or the lithium-ion fluorescent probe prepared by the preparation method described in the above technical solution in lithium-ion detection.

[0020] The lithium-ion fluorescent probe provided by this invention has an emission wavelength in the visible and near-infrared regions and an emitting group with a high fluorescence quantum yield. It also has a crown ether recognition site, which is a highly selective response site for lithium ions. Therefore, the fluorescence signal of the probe molecule changes significantly before and after binding with lithium ions, thereby achieving the purpose of quantitative detection of lithium ions. Moreover, the fluorescent probe molecule has high selectivity and sensitivity to lithium ions. Detailed Implementation

[0021] This invention provides a lithium-ion fluorescent probe having the structure shown in Formula 1:

[0022]

[0023] This invention provides a method for preparing the lithium-ion fluorescent probe described in the above technical solution, comprising the following steps:

[0024] N-hexa-12-crown-4,4-bromo-1,8-naphthalenedicarboxylic anhydride and ethylene glycol monomethyl ether were mixed and subjected to the first reaction to give the first compound;

[0025] The first compound, ethylenediamine, and DMF were mixed to carry out a second reaction, yielding a second compound;

[0026] Diethylene glycol monomethyl ether, sodium hydroxide, tetrahydrofuran, p-toluenesulfonyl chloride and water were mixed and subjected to a third reaction to obtain a third compound;

[0027] The second compound, the third compound, and THF were mixed and subjected to a fourth reaction to obtain a lithium-ion fluorescent probe.

[0028] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0029] In this invention, N-hexa-12-crown-4,4-bromo-1,8-naphthalenedicarboxylic anhydride and ethylene glycol monomethyl ether are mixed and subjected to a first reaction to obtain a first compound.

[0030] In this invention, the molar ratio of N-hexa-12-crown-4 to 4-bromo-1,8-naphthalenedicarboxylic anhydride is preferably 0.5-2:0.5-2, more preferably 1:1; the amount of ethylene glycol monomethyl ether (as a solvent) is not specifically limited in this invention, and can be adjusted according to actual needs to ensure the smooth progress of the reaction.

[0031] In this invention, the first reaction is preferably carried out under reflux conditions; the reaction time is preferably 3 to 5 hours, more preferably 4 hours.

[0032] After the first reaction is completed, the present invention preferably pours the obtained reaction solution into ice water, and then performs filtration and drying in sequence to obtain the first compound.

[0033] After obtaining the first compound, the present invention mixes the first compound, ethylenediamine and DMF, and carries out a second reaction to obtain the second compound.

[0034] In this invention, the preferred mass ratio of the first compound to ethylenediamine is (3.5-4):1, more preferably 3.71:1; the present invention does not impose any special limitation on the amount of DMF used, and can be adjusted according to actual needs to ensure the smooth progress of the reaction.

[0035] In this invention, the second reaction is preferably carried out under reflux conditions; the time of the second reaction is preferably 10-15 h, more preferably 12 h.

[0036] After the second reaction is completed, the present invention preferably pours the obtained reaction solution into ice water, and then performs filtration and drying in sequence to obtain the second compound.

[0037] In this invention, diethylene glycol monomethyl ether, sodium hydroxide, tetrahydrofuran, p-toluenesulfonyl chloride and water are mixed and subjected to a third reaction to obtain a third compound.

[0038] In this invention, the molar ratio of diethylene glycol monomethyl ether, sodium hydroxide, and p-toluenesulfonyl chloride is preferably 40-60:170-180:50-70, more preferably 50:175:60; the volume ratio of tetrahydrofuran to water is preferably 1:1; this invention does not have a special limitation on the total amount of tetrahydrofuran and water, and can be adjusted according to actual needs to ensure the smooth progress of the reaction.

[0039] In this invention, the p-toluenesulfonyl chloride is preferably used in solution form, and the solvent used is preferably tetrahydrofuran (THF).

[0040] In this invention, diethylene glycol monomethyl ether, sodium hydroxide, tetrahydrofuran, and water are stirred evenly at 0°C. A THF solution of p-toluenesulfonyl chloride is then added dropwise to the resulting mixture over a period of ≥2 hours. After the addition is complete, the resulting mixture is subjected to a third reaction under stirring conditions.

[0041] In this invention, the temperature of the third reaction is preferably room temperature, and the time is preferably 12 to 16 hours, more preferably 13 to 15 hours.

[0042] After completing the third reaction, the present invention pours the obtained reaction product into hydrochloric acid aqueous solution, extracts it three times with dichloromethane, collects the organic phase, dries it with anhydrous sodium sulfate, evaporates it to dryness, and obtains the third compound.

[0043] After obtaining the second and third compounds, the present invention mixes the second and third compounds with THF and carries out a fourth reaction to obtain a lithium-ion fluorescent probe.

[0044] In this invention, the molar ratio of the second compound to the third compound is preferably 0.1:0.15 to 3, more preferably 0.1:0.15 to 2.

[0045] In this invention, THF is preferably added to the second compound, the temperature is lowered to 0°C, the mixture is stirred vigorously for 30 minutes, the third compound is added, and the fourth reaction is carried out under stirring conditions.

[0046] In this invention, the temperature of the fourth reaction is preferably room temperature, and the time is preferably 4 to 6 hours, more preferably 5 hours.

[0047] After completing the fourth reaction, the present invention preferably removes the solvent from the obtained product and passes it through a column to obtain a lithium-ion fluorescent probe. The present invention does not have any particular limitations on the solvent removal and column chromatography; any procedure well known in the art can be followed.

[0048] In this invention, the reaction formula of the lithium-ion fluorescent probe is:

[0049]

[0050] Among them, compounds 1, 2, 3 and 4 correspond to the first compound, the second compound, the third compound and the lithium-ion fluorescent probe, respectively.

[0051] This invention provides the application of the lithium-ion fluorescent probe described in the above technical solution or the lithium-ion fluorescent probe prepared by the preparation method described in the above technical solution in lithium-ion detection.

[0052] The present invention does not specifically limit the method of application; the lithium-ion fluorescent probe can be used for lithium-ion detection in accordance with methods well known in the art.

[0053] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0054] Example 1

[0055] N-hexa-12-crown-4 (35.4 mg, 0.2 mmol) and 4-bromo-1,8-naphthalenedicarboxylic anhydride (55.6 mg, 0.2 mmol) were mixed, and 5 mL of ethylene glycol monomethyl ether was added as a solvent. The mixture was heated to reflux and reacted for 4 h. After cooling, the reaction solution was poured into ice water, filtered, and dried to obtain compound 1.

[0056] 37.1 mg (0.1 mmol) of compound 1, 10 mg of ethylenediamine and 5 mL of LDMF were mixed and refluxed for 12 h. After cooling, the resulting reaction solution was poured into ice water, filtered and dried to obtain compound 2.

[0057] Diethylene glycol monomethyl ether (6.01 g, 50 mmol), sodium hydroxide (7.00 g, 175 mmol), tetrahydrofuran (35 mL), and water (35 mL) were stirred at 0 °C until homogeneous. A THF solution (50 mL) of p-toluenesulfonyl chloride (11.4 g, 60 mmol) was added dropwise to the resulting mixture over 3 h. After the addition was complete, the mixture was stirred at room temperature for 12 h. The reaction mixture was poured into an aqueous hydrochloric acid solution and extracted three times with dichloromethane. The organic phase was collected, dried over anhydrous sodium sulfate, and evaporated to dryness to give compound 3.

[0058] Compound 2 (41.3 mg, 0.1 mmol) was added to 10 mL of THF, cooled to 0 °C, and stirred vigorously for 30 min. Compound 3 (0.15 mmol) was then slowly added, and the resulting mixture was stirred at room temperature for 5 h. After the reaction, the solvent was removed, and the mixture was passed through a column to obtain compound 4, which is the lithium-ion fluorescent probe.

[0059] Characterization

[0060] The NMR characterization of compound 4 prepared in Example 1 was performed, and the results are as follows:

[0061] 8.55-8.47(m,2H),8.43(d,J=8.1Hz,1H),7.83(dd,J=8.3Hz,7.5Hz,1H),7.37(d,J=8 .1Hz,1H),7.12(t,J=7.0Hz,2H),4.23(t,J=4.8Hz,2H),3.90(t,J=4.8Hz,2H),3.73( dd,J=2.0Hz,4.8Hz,2H),3.67(qt,J=10.0,4.5Hz,2H),3.59(dd,J=2.0Hz,4.8Hz,2H) ,3.57-3.52(m,2H),3.51-3.42(m,8H),3.34(s,3H)ppm3.32(dt,J=10.2,4.8Hz,2H), 13CNMR(150MHz,DMSO-d6):190.4,163.2,161.4,161.0,156.2,132.8,131.6,131.3,129.7,128.5, 126.7,114.6,71.7,70.7,69.7,69.1,69.3,67.2,69.1,68.9,68.5,58.9,52.2,49.4,48.1,31.3.

[0062] Application examples

[0063] Polyvinyl alcohol and polyvinylpyrrolidone were mixed at a mass ratio of 3:5, and then 100 mL of a mixed solvent of N,N-dimethylformamide and chloroform (volume ratio of 2:8) was added. The resulting mixture (the total mass fraction of polyvinyl alcohol and polyvinylpyrrolidone in the mixture was 8%) was magnetically stirred at room temperature for 8 h to obtain the shell spinning solution.

[0064] Weigh 100 mL of hexafluoroisopropanol, 2.4 g of polylactic acid and 3.6 g of silk fibroin, put them into a beaker, and stir for 8 hours to obtain the core spinning solution.

[0065] 250 mL of 0.04 M iron triacetylacetone and 250 mL of 0.02 M cobalt acetate tetrahydrate solution were mixed and 500 mL of 0.5 M ammonia solution was added dropwise while stirring vigorously. After reacting at 50 °C for 2 h, an equal volume of ethanol was added, and the mixture was sonicated. Then, anhydrous diethyl ether with a volume three times that of ethanol was added, and magnetic separation was performed in the magnetic field of a 0.5 T permanent magnet to obtain iron-cobalt nanoparticles.

[0066] 0.5g of the lithium-ion fluorescent probe prepared in Example 1 and 5g of superparamagnetic particles (iron-cobalt nanoparticles) were weighed and added to the shell and core electrospinning solutions, respectively. The solutions were then loaded into 50mL syringes. Coaxial electrospinning was performed at a temperature of 25℃, a needle tip positive and negative voltage of 19kV and 0.2kV, a needle tip distance of 16cm from the fiber membrane collection device, and flow rates of 0.20mm / min and 0.30mm / min for the core and shell electrospinning solutions, respectively. The resulting wet fiber membrane was dried at 30℃ for 1h to obtain a coaxial core / shell electrospinned nanofiber membrane. After drying, a lithium-ion detector was obtained.

[0067] The lithium-ion detector described above is cut to a suitable size for simulating the detection of lithium-ion concentration in brine. The specific steps include:

[0068] (1) Prepare lithium ion sample solutions of different concentrations according to the concentration gradient principle;

[0069] (2) The accurate concentration of each sample was determined using the standard ICP-Ms method;

[0070] (3) Titrate the lithium ion sample solution of known concentration tested in step (2) onto the detector prepared in Example 1 above, irradiate it with 254nm ultraviolet light for 1 min, observe the color and make a color card to obtain a color card with a certain concentration range; drop the lithium ion sample solution to be tested onto the detection device, irradiate it with 254nm ultraviolet light for 1 min, observe the color and match it with the color card to obtain the lithium ion concentration in the lithium ion sample solution to be tested, and compare it with the concentration tested in step (2).

[0071] The results show that the deviation between the lithium ion concentration measured by the detector prepared in Example 1 and the lithium ion concentration measured by the standard ICP-MS method is less than 0.5%, indicating that the detector of the present invention can accurately measure the lithium ion concentration.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lithium-ion fluorescent probe, characterized in that, It has the structure shown in Equation 1: Formula 1.

2. The method for preparing the lithium-ion fluorescent probe according to claim 1, characterized in that, Includes the following steps: N-hexa-12-crown-4 and 4-bromo-1,8-naphthalenedicarboxylic anhydride were mixed with ethylene glycol monomethyl ether and subjected to the first reaction to give the first compound; The first compound, ethylenediamine, and DMF were mixed to carry out a second reaction, yielding a second compound; Diethylene glycol monomethyl ether, sodium hydroxide, tetrahydrofuran, p-toluenesulfonyl chloride and water were mixed and subjected to a third reaction to obtain a third compound; The second compound, the third compound, and THF were mixed and subjected to a fourth reaction to obtain a lithium-ion fluorescent probe.

3. The preparation method according to claim 2, characterized in that, The molar ratio of N-hexa-12-crown-4 to 4-bromo-1,8-naphthalenedicarboxylic anhydride is 0.5~2:0.5~2; the reaction time is 3~5 h.

4. The preparation method according to claim 2, characterized in that, The mass ratio of the first compound to ethylenediamine is (3.5~4):1; the reaction time is 10~15h.

5. The preparation method according to claim 2, characterized in that, The molar ratio of diethylene glycol monomethyl ether, sodium hydroxide, and p-toluenesulfonyl chloride is 40~60:170~180:50~70; the third reaction is carried out at room temperature for 12~16 hours.

6. The preparation method according to claim 2, characterized in that, The molar ratio of the second compound to the third compound is 0.1:0.15~0.

3.

7. The preparation method according to claim 2, characterized in that, The fourth reaction was carried out at room temperature for 4 to 6 hours.

8. The application of the lithium-ion fluorescent probe according to claim 1 or the lithium-ion fluorescent probe prepared by any one of claims 2 to 7 in the detection of lithium ions for purposes other than disease diagnosis or treatment.

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