Thienyl oxazole formylhydrazine Al < 3 + > fluorescent probe and preparation method thereof

Abstract

The invention relates to a thienyl oxazole formylhydrazine Al < 3 + > fluorescent probe and a preparation method thereof. The preparation method comprises the following steps: reacting thiophene-2-carbonyl chloride with ethyl isocyanoacetate to generate a cyclic compound, so as to obtain an intermediate 1; carrying out acylation reaction on the intermediate 1 and hydrazine hydrate to obtain a compound SON; oxidizing 2, 6-bis (hydroxymethyl)-p-cresol to obtain an intermediate 2; the intermediate 2 and a compound SON are subjected to an amine-aldehyde condensation reaction, and the thienyl oxazole formylhydrazine Al < 3 + > fluorescent probe is prepared. The thienyl oxazole formylhydrazine Al < 3 + > fluorescent probe is high in preparation yield, high in sensitivity and high in specific recognition capability, is suitable for pH detection in a natural environment and a water body, can generate strong blue fluorescence after being combined with metal Al < 3 + >, can realize naked eye recognition, can also be used for rapid monitoring of Al < 3 + > in the natural environment and a biological cell system, and has wide application prospects. The method has important practical application and expansion values.

Description

Technical Field

[0001] The present invention relates to a thiophenyl oxazole carbohydrazide-based Al 3+ fluorescent probe and a preparation method thereof, and specifically belongs to the technical field of organic chemistry. Background Art

[0002] Aluminum is a silver-white light metal, abundant in the earth's crust, second only to oxygen and silicon, and is the most abundant metallic element in the earth's crust. As an active metal, aluminum is relatively soft, has good electrical conductivity, thermal conductivity, heat resistance and resistance to nuclear radiation. At the same time, it 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, the automotive industry, daily utensils, electronic products, etc. 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 various harms to the human body, mainly including effects on the nervous system, osteoporosis, skin problems, and endocrine disruption. Long-term exposure to aluminum or its accumulation in the body may lead to memory loss, an increased risk of developing 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 crucial to develop a fluorescent chemical sensor that can specifically recognize, has high sensitivity, and can achieve trace monitoring of Al 3+ in industrial and water and soil environments.

[0003] With the rapid development of science and technology, many fluorescent chemical sensors have been developed by scientific researchers for the detection of Al 3+ in environmental and biological systems. However, most of the Al 3+The synthesis steps of fluorescent sensors are cumbersome, with low selectivity and solubility, poor recyclability, a narrow applicable pH range, and long response times, which limit their application in certain fields. Tian L.M et al. synthesized a new type of dual-probe aluminum ion fluorescent probe, but its synthesis steps were complex and the yield was not high. The aluminum ion fluorescent probe synthesized by Tian Z.N et al. had poor solubility, and the fluorescence performance shifted and the enhancement was not obvious. The fluorescent probe designed by Li Na et al. had a low synthesis yield and poor solubility, and its detection of aluminum ions was interfered by other ions. The response time of the fluorescent probe designed and synthesized by Zhang C.L et al. to aluminum ions reached 10 minutes, with too long a response time. The fluorescent probe designed and synthesized by Gao Huan et al. responded to aluminum ions in the pH range of 5 - 6, with a narrow applicable pH range and poor anti-interference ability of the probe. Compounds containing thiophene ring units have certain electronic tunability, and salicylaldehyde and its derivatives have good solubility. Expanding thiophene-based oxazole carbohydrazide compounds with salicylaldehyde derivatives can achieve energy level matching of compounds, provide multi-site recognition of target metal ions, have good chemical properties, are less interfered by environmental factors, have a wide pH applicable range, and can be used for real-time detection and on-site recognition. Therefore, designing and developing an Al 3+ fluorescent probe with rapid detection and specific recognition has important practical application value. Summary of the Invention

[0004] In view of the above situation, the purpose of the present invention is to provide a thiophene-based oxazole carbohydrazide Al 3+ fluorescent probe and its preparation method. The fluorescent probe of the present invention can be used for the detection of Al 3+ in biological and water environments, and has the characteristics of good solubility, specific recognition, high synthesis yield, and strong anti-interference ability.

[0005] The chemical structural formula of a thiophene-based oxazole carbohydrazide Al 3+ fluorescent probe of the present invention is: ;

[0006] The preparation method of a thiophene-based oxazole carbohydrazide Al 3+ fluorescent probe is as follows: First, react thiophene-2-carbonyl chloride with ethyl isocyanoacetate to form a cyclic compound to obtain intermediate 1; perform an acylation reaction on intermediate 1 with hydrazine hydrate to obtain compound SON; oxidize 2,6-bis(hydroxymethyl)-p-cresol to obtain intermediate 2; perform an amine-aldehyde condensation reaction on intermediate 2 and compound SON to prepare a thiophene-based oxazole carbohydrazide Al 3+ fluorescent probe; The specific steps are as follows: Step 1: Under an argon protection atmosphere, thiophene-2-carbonyl chloride and ethyl isocyanoacetate were stirred overnight at room temperature in a mixed solution of triethylamine and tetrahydrofuran, and the reaction progress was monitored by thin-layer chromatography (TLC); after the reaction was completed, the product was cooled to room temperature, subjected to column chromatography separation and elution, and the eluent was removed by rotary evaporation to obtain Intermediate 1; Step 2: Intermediate 1 and hydrazine hydrate were heated under reflux in an anhydrous ethanol solution for 1 - 2 h, the product was cooled to room temperature, subjected to column chromatography separation and elution, and the eluent was removed by rotary evaporation to obtain Compound SON; Step 3: Under an argon protection atmosphere, 2,6-bis(hydroxymethyl)-p-cresol and manganese dioxide were heated under reflux in a dichloromethane solution, the reaction progress was monitored by thin-layer chromatography, and the product was cooled to room temperature, rinsed with ethanol and subjected to column chromatography separation and elution, and the eluent was removed by rotary evaporation to obtain Intermediate 2; Step 4: Intermediate 2 and Compound SON were heated under reflux in an anhydrous ethanol solution for 4 - 6 h to precipitate a white solid; the product was filtered by suction and washed with ethanol to obtain thiophene-based oxazole formyl hydrazide Al 3+ fluorescent probe.

[0007] In the said Step 1: The molar ratio of thiophene-2-carbonyl chloride to ethyl isocyanoacetate is 1∶1, the volume ratio of the mixed solution of triethylamine and tetrahydrofuran is 1∶3, and the eluent is ethyl acetate and petroleum ether with a volume ratio of 3∶7.

[0008] In the said Step 2: The molar ratio of Intermediate 1 to hydrazine hydrate is 1∶10, and the eluent is ethyl acetate and petroleum ether with a volume ratio of 6∶4.

[0009] In the said 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 with a volume ratio of 2∶8.

[0010] In the said Step 4: The molar ratio of Intermediate 2 to Compound SON is 1∶1.

[0011] Reaction equation of the present invention: ; Among them: 1 represents Intermediate 1; SON represents Compound SON; 2 represents Intermediate 2; DQSON represents thiophene-based oxazole formyl hydrazide Al 3+ fluorescent probe compound.

[0012] The using method of the thiophene-based oxazole formyl hydrazide Al3+ fluorescent probe provided by the present invention is as follows: The using method of the thiophene-based oxazole formyl hydrazide Al 3+ fluorescent probe is to use the Al 3+The aqueous solution of the probe molecule DQSON was added dropwise to a DMF (N, N-dimethylformamide) / H2O (4:6, v / v) mixed solution, and the solution was observed to change from no fluorescence to strong blue fluorescence. 3+ There is no obvious fluorescence change in solutions of other metal cations except .

[0013] The specific steps are: Add appropriate amount of DMF / H2O (4:6, v / v) solvent to 21 5 mL centrifuge tubes, and then drop 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+ Finally, add the probe molecule DQSON dilute solution, observe under ultraviolet light, and add Al 3+ The centrifuge tube solution of the aqueous solution changed from colorless to strong blue fluorescence, while other metal cation solutions showed no fluorescence change.

[0014] Beneficial effects of the present invention: 1. The present invention adopts a simple synthesis reaction to combine a component containing a thienyl oxazole functional group with a salicylaldehyde derivative, the raw materials are cheap and readily available, the reaction steps are simple, and the yield is high; 2. The thienyl oxazole carboxylic acid hydrazide Al 3+ The fluorescent probe molecular structure is synthesized for the first time, has good solubility, strong specific recognition ability, low detection limit, and can effectively distinguish Al 3+ and other common metal ions; 3. Thienyl oxazole carboxylic acid hydrazide Al of the present invention 3+ The fluorescent probe has a wide range of applications and can show good detection performance in a wide pH range. The emission wavelength is 476 nm, showing strong blue fluorescence visible to the naked eye, and the response is rapid, which is beneficial to the detection of Al in biological cells and water environments. 3+ The analysis and detection of this product has broad application prospects and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe; Figure 2 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ nuclear magnetic resonance hydrogen spectrum ( 1 H-NMR) spectrum of the fluorescent probe; Figure 3-1 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescence spectrum of the fluorescent probe showing the relationship between fluorescence intensity and water content in the DMF / H2O system; Figure 3-2 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ relationship between the change in fluorescence intensity and water content of the fluorescent probe in the DMF / H2O system; Figure 4-1 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe's fluorescence change graph in response to Al 3+ in the DMF / H2O system; Figure 4-2 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe's ultraviolet change graph in response to Al 3+ in the DMF / H2O system; Figure 5-1 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe's fluorescence emission spectrum for different concentrations of Al 3+ in the DMF / H2O system; Figure 5-2 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ relationship between the degree of fluorescence enhancement and the concentration of Al 3+ of the fluorescent probe in the DMF / H2O system; Figure 6 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ Job curve graph of the binding of DQSON and Al 3+ by the fluorescent probe in the DMF / H2O system; Figure 7 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ fluorescence intensity change graph of the fluorescent probe under different pH conditions; Figure 8 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al 3+ detection of the anti-interference ability of the fluorescent probe in the presence of different metal ions; Figure 9 : The chemical structural formula of the thienyl oxazole carbohydrazide-based Al3+ Research diagram of the reversible cycle of the fluorescent probe. Detailed implementation manners

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification. However, it should be noted that the embodiments of the present invention include but are not limited to the following implementation manners.

[0017] Example 1 Synthesis of thiophene-based oxazole carbohydrazide Al3+ probe Synthesis of intermediate 1: Thiophene-2-carbonyl chloride (1.3852 g, 9.45 mmol) and ethyl isocyanoacetate (1.0691 g, 9.45 mmol) were dissolved in 15 mL of tetrahydrofuran solvent, 5 mL of triethylamine was added dropwise, and the reaction was stirred overnight at room temperature under argon atmosphere. 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 white liquid was obtained by rotary evaporation under reduced pressure, which was intermediate 1 with a yield of 57.3%.

[0018] Synthesis of compound SON: Intermediate 1 (1.2088 g, 5.41 mmol) was added to 10 mL of absolute ethanol, 3.3 mL of hydrazine hydrate (mass fraction 80%) was added, the oil bath temperature was set at 85°C, and the mixture was heated under reflux for 1 h until the reaction was completed (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 white solid SON (0.8206 g, yield 72.5%) was obtained by rotary evaporation under reduced pressure.

[0019] Synthesis of intermediate 2: 2,6-Bis(hydroxymethyl)-p-cresol (2.0548 g, 12.2 mmol) was dissolved in 40 mL of dichloromethane, 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 at 65°C. The mixture was heated under reflux until the reaction was completed (the reaction progress was monitored by thin layer chromatography). The reaction mixture was cooled to room temperature, filtered, and the manganese dioxide was rinsed three times with absolute 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 pale green solid intermediate 2 (1.3097 g, yield 64.6%) was obtained by rotary evaporation under reduced pressure.

[0020] Synthesis of the probe molecule DQSON: Intermediate 2 (0.0338 g, 0.2 mmol) and compound SON (0.0421 g, 0.2 mmol) were successively added to 5 mL of absolute ethanol. The oil bath temperature was set at 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. Vacuum filtration was used, and the solid was washed three times with a small amount of ethanol to obtain a white solid product, which was the probe DQSON (0.0457 g, yield 63.9%).

[0021] Thienyl oxazole carbohydrazide-based Al 3+ The 1H NMR spectrum of the fluorescent probe is as Figure 2 shown below. 1 1H NMR (500 MHz, DMSO- d d6) δ 12.22 (s, 1H), 11.54 (s, 1H), 8.51 (s, 1H), 7.91 (d, J J = 5.1 Hz, 2H), 7.25 (q, J J = 2.8, 1.9 Hz, 2H), 7.14 (s, 1H), 5.08 (t, J J = 5.7 Hz, 1H), 4.57 - 4.53 (m, 3H), 2.28 (s, 3H). From the spectrum, it can be determined that the structure of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe prepared in this invention is consistent with the target molecule.

[0022] Example 2 Thienyl oxazole carbohydrazide-based Al 3+ Water content analysis of the fluorescent probe

[0023] The DMF / H2O system was used as the experimental test condition.

[0024] The thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe was dissolved in DMF solvent and diluted to a 50 mL volumetric flask to prepare a standard solution with a concentration of 1 mmol / L as the detection standard solution.

[0025] Nine 5 mL centrifuge tubes were taken, and the total volume of the solvent in each tube was set to 3 mL. The concentration ratio of the probe DQSON to Al 3+ was 1:10. 0.3 mL of the Al solution with a concentration of 1 mmol / L was added to each centrifuge tube respectively. 3+An aqueous solution was added with mixed solvents with a volume ratio of DMF / H₂O of 1∶9, 2∶8, 3∶7, 4∶6, 5∶5, 6∶4, 7∶3, 8∶2, and 9∶1 respectively, and finally 0.03 mL of a detection standard solution with a concentration of 1 mmol / L was added. The above samples were left standing for 1 minute and then transferred to a standard quartz cuvette, and the fluorescence spectrum change curves were measured respectively. The excitation wavelength was set at 392 nm and the maximum emission wavelength was 476 nm.

[0026] Thienyl oxazole carbohydrazide-based Al 3+ Water content analysis of the fluorescent probe and the fluorescence response effect are as Figure 3-1 shown. Figure 3-2 The results showed that when the volume ratio of DMF / H₂O was 4∶6, the fluorescence of the probe molecule DQSON was the strongest when combined with Al 3+ Therefore, the DMF / H₂O (4∶6, v / v) system was selected as the experimental test condition.

[0027] Example 3 Thienyl oxazole carbohydrazide-based Al 3+ Fluorescent probe for Al 3+ Selective detection of fluorescence and ultraviolet response to Al

[0028] The DMF / H₂O (4∶6, v / v) system was used as the experimental test condition.

[0029] Take 22 5-mL centrifuge tubes, add 1.17 mL of DMF solvent and 1.5 mL of deionized water to each centrifuge tube respectively. The first centrifuge tube was used as a blank control group, and 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+An aqueous solution, and finally 0.03 mL of a detection standard solution with a concentration of 1 mmol / L was added. The above sample solution was allowed to stand for 1 minute, and then transferred to a standard quartz cuvette, and the fluorescence spectrum and ultraviolet spectrum change curves were measured respectively. The excitation wavelength was set at 392 nm, and the maximum emission wavelength was 476 nm.

[0030] Thienyl oxazole carbohydrazide-based Al 3+ Fluorescent probe for Al 3+ The fluorescence effect on Al is as Figure 4-1 shown, and the change in the ultraviolet spectrum is as Figure 4-2 shown. The results show that after the probe molecule DQSON binds to Al 3+ , a significant fluorescence enhancement phenomenon appears at 476 nm, and an obvious red shift phenomenon appears in the ultraviolet spectrum. The research results show that the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe for Al 3+ has high sensitivity and excellent selectivity.

[0031] Example 4 Thienyl oxazole carbohydrazide-based Al 3+ Fluorescent probe for Al 3+ Quantitative fluorescence detection of Al

[0032] The DMF / H2O (4:6, v / v) system was used as the experimental test condition.

[0033] Take 16 5-mL centrifuge tubes, add 1.17 mL of DMF solvent and 1.17 - 1.8 mL of deionized water to each centrifuge tube respectively, and then add 0 eq - 3 eq (concentration of 1 mmol / L) of Al 3+ (0 - 0.09 mL) aqueous solution to each centrifuge tube. Finally, add 0.03 mL of a detection standard solution with a concentration of 1 mmol / L to each centrifuge tube. After the above samples were allowed to stand for 1 minute, they were transferred to a standard quartz cuvette, and the change in their fluorescence spectrum was measured.

[0034] Thienyl oxazole carbohydrazide-based Al 3+ Fluorescent probe for different concentrations of Al 3+ The fluorescence emission spectrum is as Figure 5-1 shown. The fluorescence intensity value at 476 nm in the fluorescence emission spectrum was plotted against the corresponding Al 3+ concentration (as Figure 5-2 shown), and the results showed a good linear relationship, indicating that the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe involved in the present invention can quantitatively detect the Al 3+ concentration in the DMF / H2O system.

[0035] Example 5 The complexation ratio of the probe molecule DQSON and Al in the solution system 3+

[0036] The DMF / H2O (4:6, v / v) system was used as the experimental test condition.

[0037] Take 9 5-mL centrifuge tubes, control the sum of the concentrations of the probe DQSON and Al 3+ to be 50 μM. Add solutions with molar ratios of the probe molecule DQSON solution / Al 3+ aqueous solution of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 to each centrifuge tube respectively. Then add DMF solvent (1.065 - 1.185 mL) and deionized water (1.665 - 1.785 mL) respectively to keep the total volume of the system at 3 mL. Let the above samples stand for 1 minute, then transfer them to a standard quartz cuvette and measure the fluorescence value at 476 nm.

[0038] Thienyl oxazole carbohydrazide-based Al 3+ The Job curve of the binding of the fluorescence probe between the probe molecule DQSON and Al in the DMF / H2O system 3+ is as shown in Figure 6 The result shows that the intersection occurs when [Al 3+ / ([DQSON] + [Al 3+ ) is 0.67, indicating that the complexation ratio of the thienyl oxazole carbohydrazide-based Al 3+ fluorescence probe between the probe molecule DQSON and Al in the DMF / H2O system 3+ is 1:2.

[0039] Example 6 Effect of pH on the recognition performance of thienyl oxazole carbohydrazide-based Al 3+ fluorescence probe

[0040] The DMF / H2O (4:6, v / v) system was used as the experimental test condition.

[0041] Prepare 11 groups of aqueous solutions with different pH values in the range of 2 - 12 as pH buffer solutions.

[0042] Take 22 5-mL centrifuge tubes, divide them into two groups, with 11 sample tubes in each group. In the first group, add 1.17 mL of DMF solvent, 1.5 mL of pH buffer solution with pH values from 2 to 12, and 0.3 mL of Al solution with a concentration of 1 mmol / L to each sample tube 3+ ​An aqueous solution, 0.03 mL of a detection standard solution with a concentration of 1 mmol / L. In each sample tube of the second group, 1.17 mL of DMF solvent, 1.8 mL of a pH buffer solution with a pH of 2 - 12, and 0.03 mL of a detection standard solution with a concentration of 1 mmol / L were added. The above sample solution was allowed to stand for 1 minute, transferred to a standard quartz cuvette, and the fluorescence intensity value at 476 nm was measured.

[0043] Thienyl oxazole carbohydrazide - type Al 3+ The fluorescence intensities of the fluorescent probe under different pH conditions are as Figure 7 shown. The results show that the DQSON probe itself exhibits weak fluorescence changes in the pH range of 2 - 12, and after the DQSON probe binds to Al 3+ , it exhibits strong fluorescence changes in the pH range of 4 - 10. The results indicate that the thienyl oxazole carbohydrazide - type Al 3+ fluorescent probe prepared in the present invention can be applied to the detection of Al 3+ under the pH conditions of the biological environment.

[0044] Example 7 Thienyl oxazole carbohydrazide - type Al 3+ Detection of the anti - interference ability of the fluorescent probe

[0045] The DMF / H2O (4∶6, v / v) system was used as the experimental test condition.

[0046] Forty - four 5 - mL centrifuge tubes were taken and divided into two groups, with 22 sample tubes in each group.

[0047] In each sample tube of the first group, 1.17 mL of DMF solvent and 1.5 mL of deionized water were added; the first sample tube was used as a blank control group, and in the remaining 21 centrifuge tubes, 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+ , Ce3+ , Zr 4+ and Al 3+ aqueous solution, and finally add 0.03 mL of the detection standard solution.

[0048] In each sample tube of the second group, add 1.17 mL of DMF solvent, 1.2 mL of deionized water, and 0.3 mL of an aqueous solution of Al with a concentration of 1 mmol / L 3+ aqueous solution; Use the first sample tube as a blank control group, and add 0.3 mL of an aqueous solution containing Li with a concentration of 1 mmol / L to the remaining 19 centrifuge tubes + , 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+ aqueous solution, and finally add 0.03 mL of the detection standard solution with a concentration of 1 mmol / L. Let the above sample solutions stand for 1 minute, then transfer them to standard quartz cuvettes and measure their fluorescence intensity values at 476 nm.

[0049] The anti-interference ability of the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe is as Figure 8 shown. The results show that there is almost no fluorescence in the solution without the addition of Al 3+ . After adding Al 3+ to the solution, except for Fe 2+ , Fe 3+ , Cu 2+ with slightly weaker fluorescence, the fluorescence of the aqueous solutions of other ions increases significantly. The results indicate that the thienyl oxazole carbohydrazide-based Al 3+ fluorescent probe prepared in the present invention has strong anti-interference ability in the presence of different metal ions.

[0050] Example 8 The thienyl oxazole carbohydrazide-based Al 3+Experimental Study on the Reversible Cycle of Fluorescent Probes

[0051] The DMF / H2O (4∶6, v / v) system was used as the experimental test condition.

[0052] Take 3 3-mL centrifuge tubes, number them, add 1.17 mL of DMF solvent to each centrifuge tube. Add 1.8 mL of deionized water to the first centrifuge tube; add 1.77 mL of deionized water and 0.03 mL of an aqueous solution of Al 3+ with a concentration of 1 mmol / L to the second centrifuge tube; add 1.74 mL of deionized water, 0.03 mL of an aqueous solution of Al 3+ with a concentration of 1 mmol / L, and 0.03 mL of an aqueous solution of disodium ethylenediaminetetraacetate (EDTA-2Na) with a concentration of 1 mmol / L to the third centrifuge tube. Finally, add 0.03 mL of a detection standard solution with a concentration of 1 mmol / L to each centrifuge tube. After standing the above sample solutions for 1 minute, transfer them to standard quartz cuvettes and measure their fluorescence intensity values at 476 nm. Repeat the above steps three times to draw the effect diagram of reversibility study.

[0053] The reversibility study of thienyl oxazole carbohydrazide-based Al 3+ fluorescent probes is as Figure 9 shown. The results show that by using the treatment method of alternately adding Al 3+ and EDTA-2Na to study the reversibility of the probe DQSON, after continuously adding Al 3+ and EDTA-2Na, the fluorescence intensity of DQSON-Al 3+ gradually decreases, and with the addition of EDTA-2Na, the fluorescence intensity is further quenched, indicating that the probe DQSON has good reversibility and can be recycled.

Claims

1. A thiophenyl oxazole formyl hydrazine-based Al 3+ fluorescent probe, characterized in that: The described thiophenyl oxazole formyl hydrazine-based Al 3+ The chemical structural formula of the fluorescent probe is as follows: 。 2. A preparation method of a thiophenyl oxazole formyl hydrazide-based Al 3+ fluorescent probe, characterized in that: The preparation method is as follows: First, react thiophene-2-carbonyl chloride with ethyl isocyanoacetate to generate a cyclic compound, obtaining intermediate 1; react intermediate 1 with hydrazine hydrate in an acylation reaction to obtain compound SON; oxidize 2,6-bis(hydroxymethyl)-p-cresol to obtain intermediate 2; perform an aminobenzaldehyde condensation reaction on intermediate 2 and compound SON to prepare thiophene-based oxazole formyl hydrazide Al 3+ Fluorescent probe; The specific steps are as follows: Step 1: Under an argon protection atmosphere, thiophene-2-carbonyl chloride and ethyl isocyanoacetate are stirred overnight at room temperature in a mixed solution of triethylamine and tetrahydrofuran, and the reaction progress is monitored by thin-layer chromatography; after the reaction is completed, the product is cooled to room temperature, subjected to column chromatography separation and elution, and the eluent is removed by rotary evaporation to obtain Intermediate 1; Step 2: Intermediate 1 and hydrazine hydrate are heated under reflux in an anhydrous ethanol solution for 1 - 2 h, the product is cooled to room temperature, subjected to column chromatography separation and elution, and the eluent is removed by rotary evaporation to obtain Compound SON; Step 3: Under an argon protection atmosphere, 2,6-bis(hydroxymethyl)-p-cresol and manganese dioxide are heated under reflux in a dichloromethane solution, the reaction progress is monitored by thin-layer chromatography, the product is cooled to room temperature, rinsed with ethanol and subjected to column chromatography separation and elution, and the eluent is removed by rotary evaporation to obtain Intermediate 2; Step 4: Intermediate 2 and compound SON are heated under reflux in an absolute ethanol solution for 4 - 6 h to precipitate a white solid; the product is filtered by suction and washed with ethanol to obtain a thiophene-based oxazole formyl hydrazide Al 3+ fluorescent probe.

3. A preparation method of a thiophenyl oxazole formyl hydrazine-based Al 3+ fluorescent probe, characterized in that: In the said Step 1: The molar ratio of thiophene-2-carbonyl chloride to ethyl isocyanoacetate is 1∶1, the volume ratio of the mixed solution of triethylamine and tetrahydrofuran is 1∶3, and the eluent is ethyl acetate and petroleum ether with a volume ratio of 3∶7.

4. A preparation method of a thiophenyl oxazole formyl hydrazine-based Al 3+ fluorescent probe, characterized in that: In the said Step 2: The molar ratio of Intermediate 1 to hydrazine hydrate is 1∶10, and the eluent is ethyl acetate and petroleum ether with a volume ratio of 6∶4.

5. A preparation method of a thiophenyl oxazole formyl hydrazide-based Al 3+ fluorescent probe, characterized in that: In the said 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 with a volume ratio of 2∶8.

6. A preparation method of a thiophenyl oxazole formyl hydrazine-based Al 3+ fluorescent probe, characterized in that: In the said Step 4: The molar ratio of Intermediate 2 to Compound SON is 1∶1.

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