A class of thienyl oxazohydrazide Al 3+ Fluorescent probes and methods of making the same

Abstract

The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of thienyl oxazolyl formyl hydrazine class Al 3+ The application relates to a fluorescent probe and a preparation method thereof, and belongs to the technical field of organic chemistry. BACKGROUND

[0002] Aluminum is a silvery-white light metal, its content in the earth's crust is rich, second only to oxygen and silicon, and it is the most abundant metal element in the earth's crust. As a kind of active metal, aluminum is relatively soft, has good electrical conductivity, thermal conductivity, heat resistance and nuclear radiation resistance, and can form a dense oxide film in humid air to prevent further corrosion of the metal. Aluminum and its alloys play an important role in aviation, construction, automobile industry, daily utensils, electronic products and other aspects. Although aluminum and its alloys are widely used in industry and daily life, their potential hazards cannot be ignored. Excessive intake of metallic aluminum can cause a variety of hazards to the human body, mainly including nervous system effects, osteoporosis, skin problems and endocrine interference. Long-term exposure to aluminum or accumulation of aluminum in the body may cause memory loss, increase the risk of Alzheimer's disease, and may also cause skin irritation and inflammation. Aluminum is considered an endocrine disruptor, which may affect hormone balance and even have an impact on the reproductive system. Therefore, it is necessary to develop a specific recognition method with high sensitivity for Al 3+ Realizing trace monitoring is crucial.

[0003] With the rapid development of science and technology, scientific researchers have developed many fluorescent chemical sensors for the detection of Al 3+ in environmental and biological systems. However, most of the Al 3+Fluorescent sensors suffer from drawbacks such as cumbersome synthesis steps, low selectivity and solubility, poor recyclability, narrow pH applicability, and long response times, limiting their application areas. Tian L.M. et al. synthesized a novel dual-probe aluminum ion fluorescent probe, but its synthesis steps were complex and the yield was low. Tian ZN et al.'s synthesized aluminum ion fluorescent probe exhibited poor solubility, fluorescence shift, and insignificant enhancement. Li Na et al.'s designed fluorescent probe had low synthesis yield and poor solubility, and its detection of aluminum ions was susceptible to interference from other ions. Zhang CL et al.'s designed and synthesized fluorescent probe had a response time of 10 minutes for aluminum ions, which was excessively long. Gao Huan et al.'s designed and synthesized fluorescent probe responded to aluminum ions within a pH range of 5-6, but its applicable pH range was narrow, and the probe had poor anti-interference capabilities. Compounds containing thiophene ring units possess a certain degree of electronic tunability, and salicylaldehyde and its derivatives exhibit good solubility. Extending thiophene-based oxazolyl hydrazide compounds using salicylaldehyde derivatives can achieve compound energy level matching, providing multi-site recognition of target metal ions. These compounds exhibit good chemical performance, are less affected by environmental factors, and have a wide pH range, making them suitable for real-time detection and on-site identification. Therefore, this study aims to design and develop an Al-based compound with rapid detection and specific recognition capabilities. 3+ Fluorescent probes have significant practical application value. Summary of the Invention

[0004] In view of the above situation, the purpose of this invention is to provide a thienyl oxazolyl hydrazide-based Al 3+ Fluorescent probe and its preparation method. The fluorescent probe of this invention can be used in biological and aquatic environments. 3+ The detection method features good solubility, specific recognition, high synthesis yield, and strong anti-interference ability.

[0005] This invention relates to a thienyloxazolylhydrazine-based Al 3+ The chemical structural formula of the fluorescent probe is:

[0006] ;

[0007] A thienyloxazoleformylhydrazine Al 3+ The fluorescent probe preparation method is as follows: First, thiophene-2-carbonyl chloride is reacted with ethyl isocyanate to generate a cyclic compound, yielding intermediate 1; intermediate 1 is acylated with hydrazine hydrate to obtain compound SON; 2,6-bis(hydroxymethyl)-p-cresol is oxidized to obtain intermediate 2; intermediate 2 is then subjected to an amine-aldehyde condensation reaction with compound SON to obtain thiophene-based oxazolyl hydrazine Al. 3+ Fluorescent probe;

[0008] The specific steps are as follows:

[0009] Step 1: Under an argon atmosphere, thiophene-2-carbonyl chloride and ethyl isocyanate were stirred overnight at room temperature in a mixed solution of triethylamine and tetrahydrofuran. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was completed, the product was cooled to room temperature, separated and eluted by column chromatography, and the eluent was removed by rotary evaporation to obtain intermediate 1.

[0010] Step 2: Intermediate 1 and hydrazine hydrate were heated under reflux in anhydrous ethanol solution for 1-2 h. The product was cooled to room temperature, separated and eluted by column chromatography, and the eluent was removed by rotary evaporation to obtain compound SON.

[0011] Step 3: Under an argon protective atmosphere, 2,6-bis(hydroxymethyl)-p-cresol and manganese dioxide were heated to reflux in dichloromethane solution. The reaction process was monitored by thin-layer chromatography. The product was cooled to room temperature, washed with ethanol, separated and eluted by column chromatography, and the eluent was removed by rotary evaporation to obtain intermediate 2.

[0012] Step 4: Intermediate 2 and compound SON were heated under reflux in anhydrous ethanol solution for 4-6 h, precipitating a white solid; the product was filtered and washed with ethanol to obtain thienyloxazolyl hydrazide Al. 3+ Fluorescent probe.

[0013] In step 1, the molar ratio of thiophene-2-carbonyl chloride to ethyl isocyanate is 1:1, the volume ratio of the triethylamine and tetrahydrofuran mixed solution is 1:3, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 3:7.

[0014] In step 2, the molar ratio of intermediate 1 to hydrazine hydrate is 1:10, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 6:4.

[0015] In step 3, the molar ratio of 2,6-bis(hydroxymethyl)-p-cresol to manganese dioxide is 7:100, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 2:8.

[0016] In step 4, the molar ratio of intermediate 2 to compound SON is 1:1.

[0017] The reaction equation for this invention is as follows:

[0018] ;

[0019] Where: 1 represents intermediate 1; SON represents compound SON; 2 represents intermediate 2; DQSON represents thienyloxazolyl hydrazide Al 3+ Fluorescent probe compounds.

[0020] The method of using the thienyloxazolyl hydrazide-based Al3+ fluorescent probe provided by this invention is as follows:

[0021] Thiophene-based oxazolyl hydrazide Al 3+ The method of using fluorescent probes is to use Al-containing... 3+ When an aqueous solution of the probe molecule DQSON was added dropwise to a mixed solution of DMF (N,N-dimethylformamide) / H2O (4:6, v / v), the solution changed from no fluorescence to strong blue fluorescence. The addition of Al... 3+ Other metal cation solutions showed no obvious fluorescence change.

[0022] The specific operating steps are as follows:

[0023] Add appropriate amounts of DMF / H2O (4:6, v / v) solvent to 21 5 mL centrifuge tubes, and then add Li to each tube dropwise. + Na + Mg 2+ , K + Ca 2+ , Cr 3+ , Mn 2+ Fe 2+ Fe 3+ Co 2+ Ni 2+ Cu 2+ Zn 2+ Ag + Cd 2+ ,Ba 2+ Hg 2+ , Pb 2+ Ce 3+ Zr 4+ And Al 3+ An aqueous solution was prepared, and finally a dilute solution of the probe molecule DQSON was added. The results were observed under UV light, followed by the addition of Al. 3+ The solution in the centrifuge tube changed from colorless to a strong blue fluorescence, while other metal cation solutions showed no fluorescence change.

[0024] The beneficial effects of this invention are as follows: 1. This invention employs a simple synthetic reaction, combining components containing thiophene-oxazole functional groups with salicylaldehyde derivatives. The raw materials are inexpensive and readily available, the reaction steps are simple, and the yield is high; 2. The thiophene-based oxazole-formylhydrazine Al provided by this invention... 3+ The fluorescent probe molecule structure is synthesized for the first time, exhibiting good solubility, strong specific recognition ability, low detection limit, and the ability to effectively distinguish Al. 3+ Compared with other common metal ions; 3. The thienyloxazolyl hydrazine of this invention is an Al 3+ The fluorescent probe has a wide range of applications, exhibiting good detection performance over a broad pH range. It emits light at a wavelength of 476 nm, displaying strong blue fluorescence visible to the naked eye, and responds rapidly, making it beneficial for detecting Al in biological cells and aquatic environments.3+ The analysis and testing of this material has broad application prospects and practical value. Attached Figure Description

[0025] Figure 1 This invention relates to thienyloxazolylhydrazide Al 3+ Chemical structural formula of the fluorescent probe;

[0026] Figure 2 This invention relates to thienyloxazolylhydrazide Al 3+ 1H NMR spectrum of fluorescent probe ( 1 H-NMR spectrum;

[0027] Figure 3-1 This invention relates to thienyloxazolylhydrazide Al 3+ Fluorescence intensity of the fluorescent probe in the DMF / H2O system versus fluorescence spectrum of water content;

[0028] Figure 3-2 This invention relates to thienyloxazolylhydrazide Al 3+ The relationship between fluorescence intensity changes of fluorescent probes and water content in DMF / H2O system;

[0029] Figure 4-1 This invention relates to thienyloxazolylhydrazide Al 3+ Fluorescent probes for Al in DMF / H2O system 3+ Fluorescence changes in response;

[0030] Figure 4-2 This invention relates to thienyloxazolylhydrazide Al 3+ Fluorescent probes for Al in DMF / H2O system 3+ Response UV change graph;

[0031] Figure 5-1 This invention relates to thienyloxazolylhydrazide Al 3+ Fluorescent probes for different concentrations of Al in DMF / H2O system 3+ Fluorescence emission spectrum;

[0032] Figure 5-2 This invention relates to thienyloxazolylhydrazide Al 3+ The fluorescence enhancement of the fluorescent probe in the DMF / H2O system is related to Al 3+ The relationship between concentrations;

[0033] Figure 6 This invention relates to thienyloxazolylhydrazide Al 3+ Fluorescent probes in DMF / H2O system: DQSON and Al 3+ Combined Job curves;

[0034] Figure 7 This invention relates to thienyloxazolylhydrazide Al 3+ Graph showing the fluorescence intensity changes of the fluorescent probe under different pH conditions;

[0035] Figure 8 This invention relates to thienyloxazolylhydrazide Al 3+ Detection of the anti-interference ability of fluorescent probes in the presence of different metal ions;

[0036] Figure 9 This invention relates to thienyloxazolylhydrazide Al 3+ A diagram illustrating the reversible cycling of a fluorescent probe. Detailed Implementation

[0037] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the embodiments of the present invention include, but are not limited to, the following implementation methods.

[0038] Example 1

[0039] Synthesis of Thiophene-based Oxazolylhydrazide Al3+ Probes

[0040] Synthesis of intermediate 1:

[0041] Thiophene-2-carbonyl chloride (1.3852 g, 9.45 mmol) and ethyl isocyanate (1.0691 g, 9.45 mmol) were dissolved in 15 mL of tetrahydrofuran solvent, and 5 mL of triethylamine was added dropwise. The mixture was stirred overnight at room temperature under an argon atmosphere, and the reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was completed, the reactants were cooled to room temperature, and the crude product was separated by column chromatography (eluent: ethyl acetate: petroleum ether = 3:7, v / v). The crude product was then evaporated under reduced pressure using a rotary evaporator to obtain a white liquid, which was intermediate 1, with a yield of 57.3%.

[0042] Synthesis of compound SON:

[0043] Intermediate 1 (1.2088 g, 5.41 mmol) was added to 10 mL of anhydrous ethanol, followed by 3.3 mL of hydrazine hydrate (80% by mass). The oil bath temperature was set to 85 °C, and the mixture was heated under reflux for 1 h until the reaction was complete (the reaction progress was monitored by thin-layer chromatography). The reactants were cooled to room temperature, and the crude product was separated by column chromatography (eluent: ethyl acetate: petroleum ether = 6:4, v / v). The crude product was then evaporated under reduced pressure using a rotary evaporator to obtain a white solid SON (0.8206 g, yield 72.5%).

[0044] Synthesis of intermediate 2:

[0045] 2,6-bis(hydroxymethyl)-p-cresol (2.0548 g, 12.2 mmol) was dissolved in 40 mL of dichloromethane and heated and stirred at 65 °C for 30 min. Then, MnO2 (15 g, 172.5 mmol) was added, and the oil bath temperature was set to 65 °C. The mixture was heated under reflux until the reaction was complete (the reaction progress was monitored by thin-layer chromatography). The reaction mixture was cooled to room temperature, filtered, and the manganese dioxide was washed three times with anhydrous ethanol. The filtrate was collected, concentrated under reduced pressure to obtain the crude product, and then separated by column chromatography (eluent: ethyl acetate: petroleum ether = 2:8, v / v). The crude product was obtained by rotary evaporation under reduced pressure to obtain a pale green solid intermediate 2 (1.3097 g, yield 64.6%).

[0046] Synthesis of the probe molecule DQSON:

[0047] Intermediate 2 (0.0338 g, 0.2 mmol) and compound SON (0.0421 g, 0.2 mmol) were added sequentially to 5 mL of anhydrous ethanol. The oil bath temperature was set to 85 °C, and the mixture was heated under reflux for 6 h until the reaction was complete. After the reaction solution was cooled to room temperature, a white solid precipitated. The solid was filtered under reduced pressure and washed three times with a small amount of ethanol to obtain a white solid product, which was probe DQSON (0.0457 g, yield 63.9%).

[0048] Thiophene-based oxazolyl hydrazide Al 3+ The proton NMR spectrum of the fluorescent probe is as follows: Figure 2 As shown. 1 H NMR (500 MHz, DMSO- d 6) δ 12.22 (s, 1H), 11.54 (s, 1H), 8.51 (s, 1H), 7.91 (d, J = 5.1 Hz, 2H), 7.25 (q, J = 2.8, 1.9 Hz, 2H), 7.14 (s, 1H), 5.08 (t, J = 5.7 Hz, 1H), 4.57 - 4.53 (m, 3H), 2.28 (s, 3H).

[0049] The spectral analysis can confirm the presence of the thienyloxazolomethylhydrazine Al-type prepared in this invention. 3+ The structure of the fluorescent probe is identical to that of the target molecule.

[0050] Example 2

[0051] Thiophene-based oxazolyl hydrazide Al 3+ Water content analysis of fluorescent probes

[0052] The DMF / H2O system was used as the experimental test conditions.

[0053] Thiophene-based oxazolamide hydrazide Al 3+ The fluorescent probe was dissolved in DMF solvent and diluted to a volumetric flask with a concentration of 1 mmol / L to prepare a standard solution as the detection standard.

[0054] Take nine 5 mL centrifuge tubes, setting the total solvent volume in each tube to 3 mL. Use probes DQSON and Al... 3+ The concentration ratio was 1:10, and 0.3 mL of 1 mmol / L Al was added to each centrifuge tube. 3+ Aqueous solutions were prepared, and then mixed solvents with DMF / H₂O volume ratios of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1 were added. Finally, 0.03 mL of a 1 mmol / L standard solution was added. The samples were allowed to stand for 1 minute, then transferred to standard quartz cuvettes, and their fluorescence spectra were measured. The excitation wavelength was set to 392 nm, and the maximum emission wavelength to 476 nm.

[0055] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probe water content analysis fluorescence response effect as follows Figure 3-1 As shown. Figure 3-2 The results showed that when the DMF / H2O volume ratio was 4:6, the probe molecule DQSON reacted with Al. 3+ The fluorescence was strongest during binding, so the DMF / H2O (4∶6, v / v) system was selected as the experimental test conditions.

[0056] Example 3

[0057] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probes for Al 3+ Selective detection of fluorescence and UV response

[0058] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0059] Take 22 5 mL centrifuge tubes, and add 1.17 mL of DMF solvent and 1.5 mL of deionized water to each tube. The first centrifuge tube serves as a blank control group. Add 0.3 mL of 1 mmol / L Li-containing solvent to the remaining 21 centrifuge tubes. + Na + Mg 2+ , K + Ca 2+ , Cr 3+ , Mn 2+ Fe2+ Fe 3+ Co 2+ Ni 2+ Cu 2+ Zn 2+ Ag + Cd 2+ ,Ba 2+ Hg 2+ , Pb 2+ Ce 3+ Zr 4+ And Al 3+ An aqueous solution was prepared, and finally 0.03 mL of a 1 mmol / L standard solution was added. The sample solution was allowed to stand for 1 minute, then transferred to a standard quartz cuvette, and its fluorescence and ultraviolet spectral changes were measured. The excitation wavelength was set to 392 nm, and the maximum emission wavelength was set to 476 nm.

[0060] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probes for Al 3+ Fluorescent effect such as Figure 4-1 As shown, the ultraviolet spectrum changes are as follows Figure 4-2 As shown. The results indicate that the probe molecule DQSON interacts with Al. 3+ After binding, significant fluorescence enhancement was observed at 476 nm, and a noticeable redshift was observed in the ultraviolet spectrum. The results indicate that the thienyl oxazolyl hydrazide Al of this invention… 3+ Fluorescent probes for Al 3+ It has high sensitivity and excellent selectivity.

[0061] Example 4

[0062] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probes for Al 3+ Quantitative fluorescence detection

[0063] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0064] Take 16 5 mL centrifuge tubes, add 1.17 mL of DMF solvent and 1.17–1.8 mL of deionized water to each tube, and then add 0 eq–3 eq (1 mmol / L concentration) of Al to each tube. 3+ Add 0-0.09 mL of aqueous solution to each centrifuge tube, and finally add 0.03 mL of 1 mmol / L standard solution to each tube. After the above samples stand for 1 minute, transfer them to a standard quartz cuvette and measure their fluorescence spectrum changes.

[0065] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probes for different concentrations of Al 3+ The fluorescence emission spectrum is as follows Figure 5-1 As shown. The fluorescence intensity value at 476 nm in the fluorescence emission spectrum is compared with the corresponding Al. 3+ Plot the concentration (e.g.) Figure 5-2 As shown in the figure), the results show a good linear relationship, indicating that the thienyl oxazolyl hydrazide Al involved in this invention 3+ Fluorescent probes can quantitatively detect Al in the DMF / H2O system. 3+ concentration.

[0066] Example 5

[0067] In the solution system, probe molecules DQSON and Al 3+ Complexation ratio

[0068] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0069] Take nine 5 mL centrifuge tubes and control the DQSON and Al probes. 3+ The sum of the concentrations was 50 μM. DQSON solution / Al was added to each centrifuge tube. 3+ Solutions with aqueous solutions in molar ratios of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1 were prepared, and DMF solvent (1.065-1.185 mL) and deionized water (1.665-1.785 mL) were added respectively to maintain a total system volume of 3 mL. The samples were allowed to stand for 1 minute, then transferred to a standard quartz cuvette, and their fluorescence value at 476 nm was measured.

[0070] Thiophene-based oxazolyl hydrazide Al 3+ Fluorescent probes in DMF / H2O system: probe molecules DQSON react with Al 3+ Combined Job curves, such as Figure 6 As shown. The results show [Al] 3+ ] / {[DQSON]+[Al 3+ The intersection occurs when the value is 0.67, indicating that the thienyloxazolyl hydrazide Al involved in this invention... 3+ Fluorescent probes in DMF / H2O system: probe molecules DQSON react with Al 3+ The complexation ratio is 1:2.

[0071] Example 6

[0072] pH affects thienyloxazolamide hydrazide Al 3+ Impact of fluorescent probe recognition performance

[0073] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0074] Eleven groups of aqueous solutions with different pH values ​​ranging from 2 to 12 were prepared as pH buffer solutions.

[0075] Take 22 5 mL centrifuge tubes and divide them into two groups of 11 sample tubes each. In the first group, add 1.17 mL of DMF solvent, 1.5 mL of pH buffer solution (pH 2-12), and 0.3 mL of 1 mmol / L Al to each sample tube. 3+ For the first group, add 0.03 mL of an aqueous solution and 0.03 mL of a 1 mmol / L standard detection solution. For the second group, add 1.17 mL of DMF solvent, 1.8 mL of a pH buffer solution (pH 2-12), and 0.03 mL of a 1 mmol / L standard detection solution to each sample tube. Let the sample solutions stand for 1 minute, then transfer them to a standard quartz cuvette and measure their fluorescence intensity at 476 nm.

[0076] Thiophene-based oxazolyl hydrazide Al 3+ The fluorescence intensity of the fluorescent probe under different pH conditions, such as Figure 7 As shown. The results show that the DQSON probe itself exhibits weak fluorescence changes in the pH range of 2-12, and the DQSON probe reacts with Al... 3+ After binding, it exhibits strong fluorescence changes within a pH range of 4-10. The results indicate that the thienyloxazolyl hydrazide Al prepared in this invention... 3+ Fluorescent probes are suitable for use in biological environments under pH conditions. 3+ Testing.

[0077] Example 7

[0078] Thiophene-based oxazolyl hydrazide Al 3+ Anti-interference ability detection of fluorescent probes

[0079] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0080] Take 44 5 mL centrifuge tubes and divide them into two groups of 22 sample tubes each.

[0081] In the first group, 1.17 mL of DMF solvent and 1.5 mL of deionized water were added to each sample tube; the first sample tube served as a blank control group.

[0082] The remaining 21 centrifuge tubes were each added with 0.3 mL of a 1 mmol / L solution containing Li. + Na + Mg 2+ , K +Ca 2+ ,Cr 3+ , Mn 2+ Fe 2+ Fe 3+ Co 2+ Ni 2+ Cu 2+ Zn 2+ Ag + Cd 2+ Ba 2+ Hg 2+ , Pb 2+ Ce 3+ Zr 4+ And Al 3+ The aqueous solution was then followed by 0.03 mL of the detection standard solution.

[0083] In the second group, each sample tube was filled with 1.17 mL of DMF solvent, 1.2 mL of deionized water, and 0.3 mL of 1 mmol / L Al. 3+ Aqueous solution;

[0084] The first sample tube served as a blank control group, while the remaining 19 centrifuge tubes were each added with 0.3 mL of a 1 mmol / L solution containing Li. + Na + Mg 2+ , K + Ca 2+ , Cr 3+ , Mn 2+ Fe 2+ Fe 3+ Co 2+ Ni 2+ Cu 2+ Zn 2+ Ag + Cd 2 + Ba 2+ Hg 2+ , Pb 2+ Ce 3+ Zr 4+ And Al 3+ Add 0.03 mL of a 1 mmol / L standard solution to the aqueous solution. Let the sample solution stand for 1 minute, then transfer it to a standard quartz cuvette and measure its fluorescence intensity at 476 nm.

[0085] Thiophene-based oxazolyl hydrazide Al 3+ The anti-interference ability of fluorescent probes, such as Figure 8As shown. The results show that without the addition of Al 3+ The solution showed almost no fluorescence, and Al was added to the solution. 3+ After that, except for Fe 2+ Fe 3+ Cu 2+ The fluorescence was slightly weak, while the fluorescence of other ionized aqueous solutions was significantly enhanced. These results indicate that the thienyloxazolyl hydrazide Al prepared in this invention... 3+ Fluorescent probes exhibit strong resistance to interference in the presence of different metal ions.

[0086] Example 8

[0087] Thiophene-based oxazolyl hydrazide Al 3+ Reversible Cyclic Experiment Study of Fluorescent Probes

[0088] The DMF / H2O (4∶6, v / v) system was used as the experimental test conditions.

[0089] Take three 3 mL centrifuge tubes and label them. Add 1.17 mL of DMF solvent to each tube. Add 1.8 mL of deionized water to the first tube; add 1.77 mL of deionized water and 0.03 mL of 1 mmol / L Al to the second tube. 3+ Aqueous solution; add 1.74 mL of deionized water and 0.03 mL of 1 mmol / L Al to the third centrifuge tube. 3+ Add 0.03 mL of a 1 mmol / L EDTA-2Na aqueous solution to each centrifuge tube, followed by 0.03 mL of a 1 mmol / L standard solution. After allowing the sample solution to stand for 1 minute, transfer it to a standard quartz cuvette and measure its fluorescence intensity at 476 nm. Repeat the above steps three times and plot the results of the reversibility study.

[0090] Thiophene-based oxazolyl hydrazide Al 3+ Studies on the reversibility of fluorescent probes, such as Figure 9 As shown. The results show that by alternately adding Al 3+ The reversibility of the DQSON probe was studied using the EDTA-2Na treatment method, with continuous addition of Al. 3+ After EDTA-2Na, DQSON-Al 3+ The fluorescence intensity gradually decreased, and with the addition of EDTA-2Na, the fluorescence intensity was further quenched, indicating that the probe DQSON has good reversibility and can be recycled.

Claims

1. A thienyloxazolyl hydrazide Al 3+ Fluorescent probe, characterized in that: The thienyloxazoleformylhydrazine Al 3+ The chemical structural formula of the fluorescent probe is: 。 2. A thienyloxazoleformylhydrazine derivative Al as described in claim 1 3+ A method for preparing a fluorescent probe, characterized in that: The preparation method is as follows: First, thiophene-2-carbonyl chloride is reacted with ethyl isocyanate to generate a cyclic compound, yielding intermediate 1; intermediate 1 is acylated with hydrazine hydrate to obtain compound SON: 5-(thiophene-2-yl)oxazol-4-formylhydrazine; 2,6-bis(hydroxymethyl)-p-cresol is oxidized to obtain intermediate 2: 3-(hydroxymethyl)-5-methylsalicylaldehyde; intermediate 2 is then reacted with compound SON in an amine-aldehyde condensation reaction to obtain thiophene-based oxazol-formylhydrazine Al. 3+ Fluorescent probe; The structures of intermediate 1, compound SON, and intermediate 2 are as follows: ； The specific steps are as follows: Step 1: Under an argon protective atmosphere, thiophene-2-carbonyl chloride and ethyl isocyanate were stirred overnight at room temperature in a mixed solution of triethylamine and tetrahydrofuran. The reaction progress was monitored by thin-layer chromatography. After the reaction was completed, the product was cooled to room temperature and separated and eluted by column chromatography. The eluent was removed by rotary evaporation to obtain intermediate 1. Step 2: Intermediate 1 and hydrazine hydrate were heated under reflux in anhydrous ethanol solution for 1-2 h. The product was cooled to room temperature, separated and eluted by column chromatography, and the eluent was removed by rotary evaporation to obtain compound SON. Step 3: Under an argon protective atmosphere, 2,6-bis(hydroxymethyl)-p-cresol and manganese dioxide were heated to reflux in dichloromethane solution. The reaction process was monitored by thin-layer chromatography. The product was cooled to room temperature, washed with ethanol, separated and eluted by column chromatography, and the eluent was removed by rotary evaporation to obtain intermediate 2. Step 4: Intermediate 2 and compound SON were heated under reflux in anhydrous ethanol solution for 4-6 h, precipitating a white solid; the product was filtered and washed with ethanol to obtain thienyloxazolyl hydrazide Al. 3+ Fluorescent probe.

3. A thienyloxazoleformylhydrazine Al according to claim 2 3+ A method for preparing a fluorescent probe, characterized in that: In step 1, the molar ratio of thiophene-2-carbonyl chloride to ethyl isocyanate is 1:1, the volume ratio of the triethylamine and tetrahydrofuran mixed solution is 1:3, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 3:

7.

4. A thienyloxazoleformylhydrazine Al according to claim 2 3+ A method for preparing a fluorescent probe, characterized in that: In step 2, the molar ratio of intermediate 1 to hydrazine hydrate is 1:10, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 6:

4.

5. A thienyloxazoleformylhydrazine Al according to claim 2 3+ A method for preparing a fluorescent probe, characterized in that: In step 3, the molar ratio of 2,6-bis(hydroxymethyl)-p-cresol to manganese dioxide is 7:100, and the eluent is ethyl acetate and petroleum ether in a volume ratio of 2:

8.

6. A thienyloxazoleformylhydrazine Al according to claim 2 3+ A method for preparing a fluorescent probe, characterized in that: In step 4, the molar ratio of intermediate 2 to compound SON is 1:1.

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