A cyanobiphenol Al 3+ and Zn 2+ Preparation method of fluorescent probe

Abstract

The present invention relates to a cyanobiphenol Al 3+ and Zn 2+ The fluorescent probe is prepared by first reacting 4'-hydroxybiphenyl-4-nitrile with hexamethylenetetramine under acidic conditions to obtain intermediate 1, then reacting 3-amino-2-hydroxyacetophenone with methoxyamine hydrochloride to obtain intermediate 2, and then reacting intermediate 1 and intermediate 2 to produce Al2O3, a cyanobiphenol. 3+ and Zn 2+ Fluorescent probe. The present invention relates to Al 3+ and Zn 2+ The preparation method of fluorescent probe is simple, low cost and high yield. In practical application, it has high recognition sensitivity, convenient detection, wide applicable pH range, strong anti-interference ability, can be identified by naked eye, which is beneficial to the detection of trace Al in the environment. 3+ and Zn 2+ Convenient detection.

Description

Technical Field

[0001] The present invention relates to a cyanobiphenol Al 3+ and Zn 2+ The invention discloses a method for preparing a fluorescent probe, specifically belonging to the technical field of organic synthesis. Background Art

[0002] Aluminum and its alloys are not only widely used in aviation, construction, and the automotive industry, but are also indispensable in daily life, such as in food additives such as alum and leavening agents, aluminum tableware, cookware, and cans, as well as water purifiers and pharmaceuticals. Aluminum is not essential to the human body. Excessive aluminum levels in the body can lead to neurodegeneration, memory loss, and even Alzheimer's disease. It can also impair intestinal calcium and phosphorus absorption and contribute to osteoporosis. Therefore, the ability to quickly and sensitively detect aluminum ions in the environment and in living organisms is of great practical significance.

[0003] Zinc is also an essential trace element for the human body. It is a component or activator of many important enzymes and can effectively promote growth and development, tissue repair, and immune function. However, excessive zinc intake can weaken the immune system and induce conditions such as infertility, dwarfism, and dermatitis. Zinc in the environment primarily comes from zinc mining and machinery manufacturing. Zinc ions in the environment enter the human body through bioaccumulation, and excessive intake poses a threat to human health. Therefore, the design of a fluorescent probe for detecting zinc ions is of great significance.

[0004] Currently reported detection methods for aluminum and zinc ions include electrochemical methods, atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and atomic emission spectroscopy. However, these methods generally suffer from disadvantages such as high cost, time consumption, and complex operation. Fluorescence analysis, on the other hand, has attracted widespread attention in recent years due to its advantages such as low cost, convenient detection, high sensitivity, and simple operation.

[0005] In recent years, the detection of Al 3+ and Zn 2+ Fluorescent probes are constantly being explored and optimized, but they generally have poor anti-interference ability and complex synthesis problems; and they cannot simultaneously detect Al 3+ and Zn 2+ There are few dual-channel fluorescent probes, and the scope of ion application is narrow. For example, in 2022, Jundong Wang et al. developed a new multi-purpose and convenient phenolphthalein-based Al 3+ Fluorescent probe, the probe FS is sensitive to Al 3+ After the reaction, a strong blue fluorescence is generated, but in the case of Cu 2+ 、Fe 3+ Cr 3+ 、Ni 2+ In the presence of 3+The fluorescence quenching of 3+ Specific recognition (Wang, JD; Hu,K.; Wang, HB; Sun, WW; Han, L.; Li, LH; Wei, Y., A novel-purposeconvenient Al 3+ ion fluorescent probe based on phenolphthalein. [J]. Mol.Struct. 2023, 1271); in 2018, Guang Shanyi et al. prepared fluorescein-based aluminum ion and zinc ion fluorescent probes through five complex organic reactions, achieving selective recognition effect among 12 metal ions (CN 108484618 A).

[0006] Therefore, the present invention provides a dual-channel Al2O3 with good solubility, specific recognition, strong anti-interference ability, and can realize naked eye recognition. 3+ and Zn 2+ Fluorescent probes have very important practical significance and application value. Summary of the Invention

[0007] The present invention is directed to the existing detection of Al 3+ and Zn 2+ A cyanobiphenol Al 3+ and Zn 2+ Fluorescent probe. This probe has dual selectivity, anti-interference ability, simple preparation method, wider application range of ion interference, can be identified by naked eye, convenient and fast detection, and has significant recognition effect.

[0008] The present invention provides a cyanobiphenol Al 3+ and Zn 2+ The chemical structure of the fluorescent probe is:

[0009] ;

[0010] The preparation steps are as follows:

[0011] Step 1: Synthesis of Intermediate 1

[0012] 4'-Hydroxybiphenyl-4-carbonitrile and hexamethylenetetramine were heated under reflux in a glacial acetic acid solution until the reaction was complete. After the reaction mixture was cooled to room temperature, hydrochloric acid was added dropwise with stirring. The product was then extracted with ethyl acetate. The resulting organic phase was washed with water, separated, dried over anhydrous sodium sulfate, filtered, and rotary evaporated to remove the ethyl acetate solvent to obtain intermediate 1.

[0013] Step 2: Synthesis of Intermediate 2

[0014] Methoxyamine hydrochloride, anhydrous potassium carbonate and 3-amino-2-hydroxyacetophenone were heated under reflux in an ethanol solution to complete the reaction. The product was subjected to rotary evaporation to remove ethanol and then extracted with ethyl acetate. The resulting organic phase was washed with water, dried over anhydrous sodium sulfate, filtered and rotary evaporated to remove the ethyl acetate solvent, and then separated by column chromatography to obtain intermediate 2.

[0015] Step 3: Synthesis of fluorescent probe HBA

[0016] The intermediates 1 and 2 were added to ethanol, and after the reaction was completed by heating under reflux, the product was cooled to room temperature, filtered, and recrystallized from ethanol to obtain cyanodiphenol Al 3+ and Zn 2+ Fluorescent probe HBA.

[0017] In the step 1, the heating reflux reaction time is 8 to 10 hours, and the equivalent ratio of 4'-hydroxybiphenyl-4-carbonitrile to hexamethylenetetramine is 1:(3 to 6).

[0018] In the step 2, the equivalent ratio of methoxyamine hydrochloride, anhydrous potassium carbonate and 3-amino-2-hydroxyacetophenone is 1:1:1, the heating reflux reaction time is 2 to 3 hours, and the eluent used for column chromatography separation is ethyl acetate and petroleum ether solvent in a volume ratio of 1:9.

[0019] In step 3, the equivalent ratio of intermediate 1 to intermediate 2 is 1:1, and the heating reflux reaction time is 5 to 8 hours.

[0020] The present invention cyanobiphenol Al 3+ and Zn 2+ The reaction process of the fluorescent probe is as follows:

[0021]

[0022] 4'-Hydroxybiphenyl-4-carbonitrile and hexamethylenetetramine undergo Duff aldolization reaction (also known as hexamethylenetetramine formylation reaction) under acidic conditions to obtain intermediate 1 (3'-formyl-4'-hydroxybiphenyl-4-carbonitrile), which is used as a fluorescent matrix; 3-amino-2-hydroxyacetophenone and methoxyamine hydrochloride undergo carbonylamine condensation to obtain intermediate 2, which increases solubility and provides a coordinating group; intermediate 1 and intermediate 2 undergo aldehyde-amine condensation to obtain cyanobiphenol Al 3+ and Zn 2+ Fluorescent probe (HBA).

[0023] Beneficial effects of the present invention: 1. The present invention relates to cyanodiphenol Al 3+ and Zn 2+The fluorescent probe is prepared using cyanodiphenol as the fluorescent matrix and methoxyamine-modified 3-amino-2-hydroxyacetophenone as the auxiliary ligand. The introduction of N and O heteroatoms to participate in coordination also optimizes the water solubility of the probe molecule. The preparation method is simple and has a high yield.

[0024] 2. The fluorescent probe HBA of the present invention was added with Al in a buffer solution of pH = 7.2. 3+ After that, strong green fluorescence is produced. 2+ The fluorescence then turns yellow, which can be clearly distinguished from other metal ions. It has high sensitivity and good anti-interference ability.

[0025] 3. In actual application, the fluorescent probe HBA only needs to be used for qualitative and quantitative detection through fluorescent lamp and fluorescence spectrophotometer. It is simple to operate, convenient and fast, and can realize dual-channel detection of aluminum ions and zinc ions. The recognition effect is significant and can be recognized by naked eyes. The minimum detection limit is lower than the Al in drinking water specified by the World Health Organization (WHO). 3+ and Zn 2+ The standard (7.41 μM and 76 μM) can realize trace analysis, which is beneficial to Al in the environment. 3+ and Zn 2+ Convenient detection.

[0026] 4. This invention was supported by the National Natural Science Foundation of China (21501088), the “Three Small” Key Project of Nanchang Hangkong University (2023ZD174), and the Teaching Reform Research Project (JXJG-22-8-35, JY22021, SZ2210). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Cyanobiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA added Al 3+ and Zn 2+ Ultraviolet spectrum change diagram;

[0028] Figure 2 : Cyanobiphenol Al of the present invention 3+ and Zn 2+ Fluorescence selective detection diagram of fluorescent probe HBA;

[0029] Figure 3 : Cyanobiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA added Al 3+ Fluorescence increment map;

[0030] Figure 4 : Cyanodiphenol Al of the present invention 3+ and Zn2+ Fluorescent probe HBA added Al 3+ Fluorescence intensity working curve;

[0031] Figure 5 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA added Zn 2+ Fluorescence increment map;

[0032] Figure 6 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA added Zn 2+ Fluorescence intensity working curve;

[0033] Figure 7 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA-Al 3+ Job's Plot graph;

[0034] Figure 8 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA-Zn 2+ Job's Plot graph;

[0035] Figure 9 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA-Al 3+ Figure 1 shows an ion competition experiment.

[0036] Figure 10 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probes HBA and HBA-Al 3+ Fluorescence changes at different pH;

[0037] Figure 11 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probes HBA and HBA-Zn 2+ Fluorescence changes at different pH;

[0038] Figure 12 : Cyanodiphenol Al of the present invention 3+ and Zn 2+ Fluorescent probe HBA 1 H-NMR spectrum. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the embodiments, but is not limited to the given examples.

[0040] Example 1

[0041] A cyanobiphenol Al 3+ and Zn 2+ Fluorescent probes

[0042] Synthesis of intermediate 1 (3'-formyl-4'-hydroxybiphenyl-4-carbonitrile):

[0043] 4'-Hydroxy-4-biphenylcarbonitrile (1.9520 g, 10 mmol) and hexamethylenetetramine (HMTA, 8.9510 g, 60 mmol) were dissolved in 50 mL of glacial acetic acid and refluxed for 10 h. The reaction progress was monitored by TLC. After completion of the reaction, the mixture was cooled to room temperature and 100 mL of 1M HCl solution was added dropwise. The mixture was stirred at room temperature for 10 min. The resulting mixture was extracted three times with ethyl acetate. The organic phases were combined and washed successively with water and once with saturated brine. The organic phases were dried over anhydrous sodium sulfate, filtered, and rotary evaporated to remove the ethyl acetate solvent to obtain a light yellow solid (1.830 g, 82% yield).

[0044] Synthesis of intermediate 2 (1-(3-amino-2-hydroxyphenyl)ethanone O-methyloxime):

[0045] Methoxyamine hydrochloride (0.095 g, 1 mmol) and anhydrous potassium carbonate (0.138 g, 1 mmol) were stirred in 10 mL of ethanol at room temperature for 10 min. 3-Amino-2-hydroxyacetophenone (0.1512 g, 1 mmol) was then added and refluxed for 2 h. After completion of the reaction as monitored by TLC, the ethanol was removed by rotary evaporation under reduced pressure. The product was extracted with ethyl acetate and washed three times with water. The organic phase was dried over anhydrous sodium sulfate, filtered and rotary evaporated to remove the ethyl acetate solvent, and separated by column chromatography (eluent: ethyl acetate: petroleum ether = 1:9, v / v) to obtain a brown oily liquid (0.1135 g, 63% yield).

[0046] HBA (Al-cyanobiphenol 3+ and Zn 2+ Synthesis of fluorescent probes):

[0047] The above-synthesized 3'-formyl-4'-hydroxybiphenyl-4-carbonitrile (0.1116 g, 0.5 mmol) and 1-(3-amino-2-hydroxyphenyl)ethanone O-methyloxime (0.0901 g, 0.5 mmol) were refluxed in 5 mL of ethanol solution for 5 h. After TLC detection, the mixture was cooled to room temperature and filtered. The obtained orange solid was recrystallized from ethanol to obtain cyanobiphenol Al3+ and Zn 2+ Fluorescent probe HBA (0.0130 g, 68% yield). 1 H NMR (500 MHz, DMSO- d 6): δ 13.97 (s, 1H), 11.47 (s, 1H), 9.13 (s, 1H), 8.13 (d, J = 2.5 Hz, 1H), 7.91 (q, J = 8.5 Hz, 4H),7.85 (dd, J = 8.7, 2.4 Hz, 1H), 7.51 (d, J = 7.9 Hz, 2H), 7.09 (d, J = 8.6Hz, 1H), 7.04 (t, J = 7.9 Hz, 1H), 4.01 (s, 3H), 2.33 (s, 3H).

[0048] Example 2

[0049] Cyanodiphenol Al 3+ and Zn 2+ Fluorescent probe HBA added Al 3+ and Zn 2+ Ultraviolet spectrum changes of

[0050] 38.5 mg of the fluorescent probe HBA synthesized in Example 1 was weighed and prepared into 100 mL of a 1 mM fluorescent probe HBA stock solution using DMSO (dimethyl sulfoxide); a HEPES buffer solution (N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid)) with a pH of 7.2 and a concentration of 1 mM was prepared.

[0051] Prepare 21 1 mM metal ion stock solutions including Li + ,Na + ,Mg 2+ ,Al 3+ , K + , Ca 2+ ,Cr 3+ ,Mn 2+ , Fe 2 + ,Fe 3+ ,Co 2+ , Ni 2+ ,Cu 2+ , Zn 2+ , Ag + , Cd2+ ,Ba 2+ , Hg 2+ , Pb 2+ , Ce 3+ and Zr 4+ .

[0052] The test was conducted in a buffer solution system of DMSO: HEPES = 4: 1 (v / v), pH = 7.2. 100 μL of the above fluorescent probe HBA stock solution was taken into a 5 mL centrifuge tube, and 500 μL of deionized water, Al 3+ 、Zn 2+ The probe concentration is always 25 μM, the metal ion concentration is always 125 μM, the probe dilution without metal ions is light yellow, visible to the naked eye, and the addition of Al 3+ The detection solution turns green and Zn 2+ The detection solution turns yellow and the whole spectrum is scanned with UV-visible spectrophotometer. Figure 1 HBA+Al 3+ The absorption peak of the test solution at 360 nm weakened, and a new absorption peak appeared at 432 nm; HBA+Zn 2+ The detection solution added two strong absorption peaks at 347 nm and 450 nm.

[0053] Example 3

[0054] Cyanodiphenol Al 3+ and Zn 2+ Fluorescence selectivity determination of the fluorescent probe HBA.

[0055] The test was conducted in a buffer solution system of DMSO∶HEPES = 4∶1 (v / v), pH = 7.2. 100 μL of the above fluorescent probe HBA stock solution was added to a 5 mL centrifuge tube, and 500 μL of various metal ion stock solutions (Li + , Na + , Mg 2 + , Al 3+ , K + , Ca 2+ , Cr 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Ba2+ ,Hg 2+ , Pb 2+ , Ce 3+ , Zr 4+ ), the probe concentration was always 25 μM, and the metal ion concentration was always 125 μM.

[0056] The fluorescence spectrum was measured by fluorescence emission spectrometer at 360 nm excitation wavelength. 3+ The addition of Zn significantly enhanced the fluorescence emission peak at 527 nm and produced green fluorescence; 2+ Then a new emission peak appeared at 553 nm and produced yellow fluorescence, which was different from other metal ions; this showed that the fluorescent probe HBA was sensitive to Al 3+ and Zn 2+ With specific recognition, fluorescence spectrum see Figure 2 shown.

[0057] Example 4

[0058] Cyanodiphenol Al 3+ and Zn 2+ Al of fluorescent probe HBA 3+ Fluorescence titration experiments.

[0059] The test was conducted in a buffer solution system of DMSO∶HEPES = 4∶1 (v / v), pH = 7.2. 100 μL of the above fluorescent probe HBA stock solution was added to a 5 mL centrifuge tube, and different volumes of Al 3+ The stock solution (20 μL, 30 μL, 40 μL, 50 μL, 60 μL, 70 μL, 80 μL, 90 μL, 100 μL) was measured by fluorescence spectrometer at an excitation wavelength of 360 nm. Figure 3 As shown); with fluorescent probe [Al 3+ ] / 10 -5 M is the horizontal axis, and the fluorescence intensity at 527 nm is the vertical axis. The working curve is plotted ( Figure 4 The limit of detection (LOD) was calculated to be 1.12×10 -6 M.

[0060] Example 5

[0061] Cyanodiphenol Al 3+ and Zn 2+ Zn fluorescent probe HBA 2+ Fluorescence titration experiments.

[0062] The test was conducted in a buffer solution system of DMSO∶HEPES = 4∶1 (v / v), pH = 7.2. 100 μL of the above fluorescent probe HBA stock solution was added to a 5 mL centrifuge tube, and different volumes of Zn 2+ The fluorescence increment was detected by fluorescence spectrometer at an excitation wavelength of 360 nm (20 μL, 40 μL, 60 μL, 80 μL, 100 μL, 200 μL, 300 μL, 400 μL, 500 μL). Figure 5 As shown); the fluorescent probe [Zn 2+ ] / 10 -5 M is the horizontal axis, and the fluorescence intensity at 553 nm is the vertical axis. The working curve is plotted ( Figure 6 The limit of detection (LOD) was calculated to be 2.02×10 -6 M.

[0063] Example 6

[0064] Cyanodiphenol Al 3+ and Zn 2+ Job's Plot curve of fluorescent probe HBA.

[0065] The test was conducted in a buffer solution system of DMSO∶HEPES= 4∶1 (v / v), pH = 7.2, and the probe HBA and Al 3+ The total concentration of the fluorescent probes HBA and Al 3+ The concentration ratios were 1∶9, 2∶8, 3∶7, 4∶6, 5∶5, 6∶4,7∶3, 8∶2, and 9∶1, respectively. The fluorescence intensity at 527 nm was detected by fluorescence spectrometer at an excitation wavelength of 360 nm. Figure 7 As shown, [Al 3+ ] / [Al 3+ ]+[HBA] reaches the maximum fluorescence intensity at 0.5, and the increase of Al 3+ The fluorescence intensity of the probe HBA and Al 3+ The complexation ratio is 1:1.

[0066] Example 7

[0067] Cyanodiphenol Al 3+ and Zn 2+ Job's Plot curve of fluorescent probe HBA.

[0068] The test was conducted in a buffer solution system of DMSO∶HEPES= 4∶1 (v / v), pH = 7.2, and the control probe HBA and Zn2+ The sum of the concentrations of the fluorescent probes HBA and Zn 2+ The concentration ratios were 1∶9, 2∶8, 3∶7, 4∶6, 5∶5, 6∶4,7∶3, 8∶2, and 9∶1, respectively. The fluorescence intensity at 553 nm was detected by fluorescence spectrometer at an excitation wavelength of 360 nm, as shown in Figure 2. Figure 8 As shown, [Zn 2+ ] / [Zn 2+ ]+[HBA] has an inflection point in fluorescence intensity at 0.5, and the increase of Zn 2+ The fluorescence intensity of the probe HBA and Zn 2+ The complexation ratio is 1:1.

[0069] Example 8

[0070] Cyanodiphenol Al 3+ and Zn 2+ Ion competition experiment of fluorescent probe HBA.

[0071] The test was conducted in a buffer solution system of DMSO∶HEPES=4∶1 (v / v), pH=7.2. Two groups of tests were prepared. 100 μL of the above fluorescent probe HBA stock solution was added to a 5 mL centrifuge tube. 200 μL of other metal ions (Li + , Na + , Mg 2+ , K + , Ca 2+ , Cr 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Ag + , Cd 2+ , Ba 2+ ,Hg 2+ , Pb 2+ , Ce 3+ , Zr 4+ ); another group added 200 μL of Al 3+ , and 200 μL of other metal ions (Li + , Na + ,Mg 2+ , K + , Ca 2+ , Cr 3+ , Mn 2+ , Fe 2+ , Fe3+ , Co 2+ , Ni 2+ , Cu 2+ ,Ag + , Cd 2+ , Ba 2+ , Hg 2+ , Pb 2+ ,Ce 3+ , Zr 4+ ).

[0072] The fluorescence intensity at 527 nm was detected by fluorescence spectrometer under 360 nm excitation wavelength. Figure 9 As shown in the bar graph, the experimental results show that other metal ions are sensitive to the recognition of Al by the probe HBA. 3+ There is almost no effect, indicating that the fluorescent probe HBA-Al 3+ Strong anti-interference ability.

[0073] Example 9

[0074] Cyanodiphenol Al 3+ and Zn 2+ Fluorescence changes of fluorescent probe HBA and ions at different pH

[0075] In DMSO: deionized water = 4:1 (v,v), three groups of test solvents with pH values of 2, 3, 4, 5, 6, 7, 8, 9, and 10 were prepared. 100 μL of the above-mentioned fluorescent probe HBA stock solution was added to the first group for measurement; 100 μL of the above-mentioned fluorescent probe HBA stock solution and 200 μL of the above-mentioned Al2O3 were added to the second group for measurement. 3+ The third group added 100 μL of the above fluorescent probe HBA stock solution and 200 μL of the above Zn 2+ The stock solution was prepared by fluorescence spectrometer with an excitation wavelength of 360 nm, and the fluorescence values at 527 nm and 553 nm were measured respectively, and a dot-line graph was drawn (see Figure 10 and Figure 11 ). Fluorescent probe HBA detects Al 3+ The pH range of application is: 2~10, the fluorescent probe HBA detects Zn 2+ The applicable pH range is: 4~10.

Claims

1. A cyanobiphenol Al 3+ and Zn 2+ A fluorescent probe, characterized in that: The Al 3+ and Zn 2+ The chemical structure of the fluorescent probe is: 。 2. A cyanobiphenol Al as claimed in claim 1 3+ and Zn 2+ The method for preparing a fluorescent probe is characterized by: The preparation method comprises the following steps: Step 1: Synthesis of Intermediate 1 4'-Hydroxybiphenyl-4-carbonitrile and hexamethylenetetramine were heated under reflux in an acetic acid solution to complete the reaction. After the reaction mixture was cooled to room temperature, hydrochloric acid was added dropwise with stirring. The product was then extracted with ethyl acetate. The resulting organic phase was washed with water, separated, dried over anhydrous sodium sulfate, filtered, and rotary evaporated to remove the ethyl acetate solvent to obtain intermediate 1. Step 2: Synthesis of Intermediate 2 Methoxyamine hydrochloride, anhydrous potassium carbonate and 3-amino-2-hydroxyacetophenone were heated under reflux in an ethanol solution to complete the reaction. The product was then subjected to rotary evaporation to remove ethanol and then extracted with ethyl acetate. The resulting organic phase was washed with water, separated, dried over anhydrous sodium sulfate, filtered and rotary evaporated to remove the ethyl acetate solvent, and then separated by column chromatography to obtain intermediate 2. Step 3: Synthesis of fluorescent probe The intermediates 1 and 2 were added to an ethanol solvent, and the reaction was completed by heating under reflux. The product was cooled to room temperature, filtered, and recrystallized from ethanol to obtain cyanodiphenol Al 3+ and Zn 2+ Fluorescent probe.

3. A cyanobiphenol Al according to claim 2 3+ and Zn 2+ The method for preparing a fluorescent probe is characterized by: In the step 1, the heating reflux reaction time is 8 to 10 hours, and the equivalent ratio of 4'-hydroxybiphenyl-4-carbonitrile to hexamethylenetetramine is 1:3 to 6.

4. a cyanobiphenol Al according to claim 2 3+ and Zn 2+ The method for preparing a fluorescent probe is characterized by: In the step 2, the equivalent ratio of methoxyamine hydrochloride, anhydrous potassium carbonate and 3-amino-2-hydroxyacetophenone is 1:1:1, the heating reflux reaction time is 2 to 3 hours, and the eluent used for column chromatography separation is ethyl acetate and petroleum ether solvent in a volume ratio of 1:

9.

5. a cyanobiphenol Al according to claim 2 3+ and Zn 2+ The method for preparing a fluorescent probe is characterized by: In step 3, the equivalent ratio of intermediate 1 to intermediate 2 is 1:1, and the heating reflux reaction time is 5 to 8 hours.

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