A schiff base compound, and a preparation method and application thereof

Abstract

This invention belongs to the field of analytical detection technology, and specifically relates to a Schiff base compound, its preparation method, and its application. The Schiff base compound of this invention is a Schiff base fluorescent probe with a 2-furanoylhydrazine core, capable of dual-response quenching-type recognition of Cu. 2+ and Fe 3+ It exhibits a clear color change under fluorescent light and shows fluorescence quenching under 365 nm ultraviolet light, providing a simple and reliable new method for rapid visual detection of dual ions.

Description

Technical Field

[0001] This invention belongs to the field of analytical detection technology, and in particular relates to a Schiff base compound, its preparation method, and its application. Background Technology

[0002] Copper ions (Cu) 2+ ) and iron ions (Fe 3+ Metal ions, as essential trace elements for the human body, are closely related to various diseases when their concentration is imbalanced. They are also common pollutants in environmental water bodies. Therefore, developing rapid, visual, and portable detection methods is of great significance. Currently, various analytical techniques for detecting metal ions have been developed, including atomic absorption spectrometry (AAS), atomic emission spectrometry (AES), and inductively coupled plasma atomic emission spectrometry (ICP). However, the practical application of these techniques is limited by high equipment costs, complex operating procedures, and slow response times.

[0003] In recent years, small molecule fluorescent probe technology has become an important tool for metal ion detection due to its extremely high sensitivity and selectivity. Although these methods can yield promising detection results, most current techniques still have significant limitations. Fluorescent probes capable of simultaneously detecting copper and iron ions are rarely reported; most existing probes exhibit fluorescence "on" or "ratio" responses, while quenching-type studies are scarce. Secondly, most probes are only visible under ultraviolet light, and systems that simultaneously produce visually perceptible color changes under sunlight are extremely rare. Therefore, this study aims to develop a novel Schiff base fluorescent probe to achieve the detection of Cu ions. 2+ and Fe 3+ The quenching-type recognition exhibits a clear color change under fluorescent light and fluorescence quenching under 365 nm ultraviolet light. The successful development of portable test strips provides a simple and reliable new method for rapid visual detection of dual ions, which is of great importance. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a Schiff base compound, its preparation method, and its applications.

[0005] In a first aspect, the present invention provides a Schiff base compound having the structure shown in Formula I:

[0006] I.

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned Schiff base compounds, comprising the following steps: It is obtained by reacting 4-dimethylaminocinnamaldehyde with 2-furanoylhydrazide.

[0008] According to some embodiments of the present invention, the temperature of the reaction is 60~90 °C; and / or the reaction time is 2~6 h.

[0009] A third aspect of the present invention provides the application of the above-described Schiff base compounds in the preparation of fluorescent probes for detecting ions, wherein the ions include Cu. 2+ and Fe 3+ .

[0010] Dimethylamino groups, as modifying groups for probes, typically exhibit higher fluorescence quantum yields, more red-shifted emission wavelengths, and more sensitive responses to microenvironments due to their stronger electron-donating effect and their role as auxochromes. Furthermore, the fluorescent probe of this invention demonstrates better selectivity and can recognize Cu using a dual-response quenching method. 2+ and Fe 3+ Furthermore, the wavelength is positioned within the visualization range for easy observation.

[0011] According to some embodiments of the present invention, the Schiff base compound specifically reacts with the ion, and the fluorescent probe undergoes fluorescence quenching under ultraviolet light excitation.

[0012] A fourth aspect of the present invention provides an ion detection test strip, comprising a reaction medium paper and a fluorescent probe loaded on the reaction medium paper, wherein the fluorescent probe is a Schiff base compound as described above, and the ion includes Cu. 2+ and Fe 3+ .

[0013] A fifth aspect of the present invention provides a method for preparing the above-described ion detection test strip, comprising the following steps: The reaction medium paper is obtained by immersing it in a fluorescent probe solution and then drying it.

[0014] According to some embodiments of the present invention, the fluorescent probe solution is obtained by dissolving the fluorescent probe in an organic solvent.

[0015] According to some preferred embodiments of the present invention, the organic solvent includes at least one of methanol, ethanol, acetone, and tetrahydrofuran.

[0016] A sixth aspect of the present invention provides a kit comprising a fluorescent probe, reaction medium paper, a solvent, and at least one of the following lights: an ultraviolet detection lamp, a fluorescent lamp, wherein the fluorescent probe is a Schiff base compound as described above, and the solvent is used to dissolve the fluorescent probe; or, It includes ion detection test strips, fluorescent colorimetric cards, and at least one of the following lights: ultraviolet detection lamp, fluorescent lamp, wherein the ion detection test strip is the aforementioned ion detection test strip.

[0017] A seventh aspect of the present invention provides the application of the above-described reagent kit in detecting ions in food ingredients, medicinal materials, or aquatic environments, wherein the ions include Cu. 2+ and Fe 3+ .

[0018] According to some embodiments of the present invention, at least the following beneficial effects are achieved: The fluorescent probe based on 2-furanoylhydrazine core provided by this invention has simple synthesis steps, naked-eye visibility, and good specificity, providing a new option for Cu... 2+ and Fe 3+ The identification provides a new fluorescent probe, enabling visualized and portable detection.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 It is probe 1. 13 C-NMR spectrum; Figure 2 It is probe 1. 1 H-NMR spectrum; Figure 3 This is the ion recognition spectrum of probe 1. In it, a shows the change in fluorescence spectrum after probe 1 recognizes copper ions and iron ions; b shows the change in UV-Vis spectrum after probe 1 recognizes copper ions and iron ions. Figure 4 These are photographs showing the color changes of probe 1 under fluorescent light and 365 nm ultraviolet light after different metal ions are added; Figure 5 These are the titration spectra of probe 1, where a shows the fluorescence spectrum changes after the gradient addition of copper ions to probe 1; b shows the fluorescence spectrum changes after the gradient addition of iron ions to probe 1; c shows a dot plot of the maximum emission peak of the fluorescence spectrum after the gradient addition of copper ions to probe 1 as a function of copper ion concentration; d shows a dot plot of the maximum emission peak of the fluorescence spectrum after the gradient addition of iron ions to probe 1 as a function of copper ion concentration; e shows the UV-Vis spectrum changes after the gradient addition of copper ions to probe 1; and f shows the UV-Vis spectrum changes after the gradient addition of iron ions to probe 1. Figure 6The graphs show the linear relationships of probe 1; where a shows the linear relationship between fluorescence intensity and copper ion concentration after probe 1 recognizes copper ions; b shows the linear relationship between fluorescence intensity and iron ion concentration after probe 1 recognizes iron ions; c shows the linear relationship of the BH equation after probe 1 recognizes copper ions; and d shows the linear relationship of the BH equation after probe 1 recognizes iron ions. Figure 7 This is a fluorescence spectrum of probe 1 for studying the properties of target metal ions; where a shows the detection capability of probe 1 for copper ions in the presence of other metal ions; b shows the detection capability of probe 1 for iron ions in the presence of other metal ions; c shows the detection capability of probe 1 for copper ions at different pH values; d shows the detection capability of probe 1 for iron ions at different pH values; e shows the detection time of probe 1 for copper ions; f shows the detection time of probe 1 for iron ions. Figure 8 This is a spectrum of the photophysical properties of probe 1; where a shows the binding ratio between probe 1 and copper ions; b shows the binding ratio between probe 1 and iron ions; c shows the relative fluorescence quantum yield after probe 1 recognizes copper ions; d shows the relative fluorescence quantum yield after probe 1 recognizes iron ions; e shows the fluorescence intensity of probe 1 in solvents of different viscosities; f shows the relationship between the fluorescence intensity of probe 1 in solvents of different viscosities and the glycerol content. Figure 9 Probe 1 identifies Cu 2+ and Fe 3+ Infrared spectrum; Figure 10 This is the NMR titration spectrum of probe 1; Figure 11 These are the mechanism diagram and density functional diagram of probe 1; Figure 12 This is a photograph of Probe 1 test strip recognizing different metal ions under a 365 nm ultraviolet light. Detailed Implementation

[0021] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0022] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0023] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0024] Unless otherwise specified, "room temperature" in this invention means 25±5 ℃.

[0025] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0026] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0027] Example 1 88 mg (0.5 mmol) of 4-dimethylaminocinnamaldehyde and 63 mg (0.5 mmol) of 2-furanoylhydrazide were dissolved in 30 mL of ethanol and reacted with magnetic stirring at 78 °C for 3 h. The synthesis of the target compound was monitored by thin-layer chromatography (TLC). After the reaction was completed, the mixture was filtered and dried to obtain probe 1.

[0028] Molecular formula: C 16 H 17 N3O2, molecular weight: 283.13. Yellow solid, yield 89%. 1 H NMR (500 MHz, Chloroform-d) δ 9.27 (s, 1H), 7.90 (d, J = 9.1 Hz, 1H), 7.48 (s, 1H), 7.36 (d, J = 8.4 Hz, 2H), 7.29 (s, 1H), 6.92 (d, J = 9.2 Hz, 1H), 6.83 (d, J =15.6 Hz, 1H), 6.68 (d, J = 8.4 Hz, 2H), 6.55 (s, 1H), 3.00 (s, 6H); 13C NMR(126 MHz, Chloroform-d) δ 151.15, 150.82, 146.94, 144.37, 141.22, 130.65,128.76, 123.98, 120.25, 116.07, 112.63, 112.22, 40.38; IR(KBr)νmax 1657.28,1597.53, 1523.23, 1469.20, 1361.89, 1292.50, 1181.53, 455.53 cm -1 .

[0029] Carbon NMR spectrum, such as Figure 1 As shown, the 1H NMR spectrum is as follows Figure 2 As shown.

[0030] Example 2 This embodiment tested the selective recognition of metal ions by probe 1.

[0031] The probe 1 was configured with a 10 μM sample in a cuvette and tested using a UV-Vis spectrophotometer and a fluorophotometer.

[0032] Test results are as follows Figure 3 As shown, probe 1 exhibits a strong fluorescence emission peak at 520 nm. (The text abruptly ends here, likely due to an incomplete translation or missing information.) 2+ and Fe 3+ Afterwards, probe 1-Cu can be observed. 2+ System and probe 1-Fe 3+ The fluorescence intensity of the system was significantly quenched at 520 nm, and under a 365 nm UV lamp, the yellow-green fluorescence of probe 1 was visible. This was observed after the addition of Cu. 2+ and Fe 3+ Post-quenching. Results show that probe 1 is effective against Cu. 2+ Fe 3+ Both are selective.

[0033] Example 3 This embodiment tested the recognition function of probe 1 for different metal ions.

[0034] Different metal ions were added to the prepared probe 1 solution, and the ultraviolet and fluorescence spectra were tested.

[0035] Test results are as follows Figure 4 As shown, probe 1 is added with Cu 2+ or Fe 3+ Afterwards, the ultraviolet-visible absorption spectrum changed after Cu was added. 2+ The absorption peak red-shifts after the addition of Fe. 3+The absorption peak then shifts to blue; specifically, under fluorescent light, the pale yellow solution of probe 1 is visible to the naked eye upon the addition of Cu. 2+ It then turns dark yellow, after which Fe is added. 3+ It then turns colorless, and the color change coincides with the shift of the absorption peak. Under a 365 nm UV lamp, the addition of Cu is visible. 2+ or Fe 3+ The obvious quenching effect is a result of the formation of complexes.

[0036] Example 4 This embodiment tested the effect of target metal ion concentration on the spectrum of probe 1 using a titration experiment.

[0037] Metal ions were added in a gradient to the prepared probe 1 solution, and the ultraviolet and fluorescence spectra were tested.

[0038] Test results are as follows Figure 5 As shown in the diagram, Cu was gradually added to the solution of probe 1. 2+ or Fe 3+ Initially, the fluorescence intensity of probe 1 changed with increasing metal ion concentration. However, once the concentration of added metal ions exceeded a certain limit, the fluorescence intensity gradually stabilized and then plateaued, indicating that the enhancing effect of metal ions on the probe solution had reached saturation. Paramagnetic copper and iron ions effectively quenched the fluorescence of the Schiff base probe through an electron transfer mechanism.

[0039] also, Figure 5 The ef in the figure indicates that, with Cu 2+ With increasing concentration, the absorption peak of probe 1 at 376 nm redshifts to 410 nm, the absorption at 376 nm gradually weakens, the absorption at 410 nm gradually strengthens, and an isoabsorption point appears at 395 nm; as Fe... 3+ With increasing concentration, the absorption of probe 1 at 376 nm gradually weakens, a new absorption peak appears at 260 nm, the maximum absorption wavelength undergoes a blue shift, and an isoabsorption point appears at 300 nm, indicating that probe 1 reacts with Cu. 2+ or Fe 3+ A stable complex was formed. The fundamental reason why the Schiff base probe exhibits opposite color changes to copper and iron ions lies in the different interaction mechanisms between the two ions and the probe. Copper ions (Cu... 2+ Iron ions (Fe) possess strong polarization ability and the Jahn-Teller effect. After coordinating with the nitrogen and oxygen atoms of a Schiff base, they enhance the electronic mobility of the entire molecule, thereby broadening the conjugated system and causing a red shift in the UV-Vis absorption spectrum, deepening the solution color from light yellow to deep yellow. 3+It has strong oxidizing properties and will oxidize and destroy the carbon-nitrogen double bond (C=N) in the Schiff base, causing structural rearrangement or hydrolysis, resulting in the conjugated system being broken and reduced. Therefore, the absorption spectrum is blue-shifted, and because the absorption peak shifts out of the visible light region, the solution is almost colorless to the naked eye.

[0040] Based on fluorescence titration data, using LOD=3 The / K equation calculation yielded the probe 1 for Cu 2+ and Fe 3+ The detection limits were 4.8714 × 10⁻⁶. -8 M and 4.0269×10 -8 M, the detection has reached the nanomolar level, which meets the requirements for trace Cu in real samples. 2+ and Fe 3+ The detection requires extremely high sensitivity; the complexation constant calculated using the BH equation is 3.1148 × 10⁻⁶. 5 M -1 and 2.2293×10 3 M -1 (See Figure 6 It can be seen that the binding of the probe to metal ions is relatively stable, among which probe 1 binds to Cu. 2+ The combination is more stable.

[0041] Example 5 This embodiment tested the anti-interference ability and practicality of probe 1 after complexing with metal ions.

[0042] After adding the target metal ion to 10 μM probe 1, an equal amount of other metal ions were added, and after mixing thoroughly, the change in fluorescence intensity of the solution was tested.

[0043] Test results are as follows Figure 7 As shown in ab, in probe 1-Cu 2+ (or 1-Fe) 3+ In the solution, an equal amount of other metal ions were added, including Fe. 3+ (Cu) 2+ This significantly reduced the fluorescence intensity, while the addition of other metal ions did not cause a significant change in fluorescence intensity; in the probe 1-Fe 3+ Add Cu to the solution 2+ Subsequently, and visibly to the naked eye, the colorless Fe3+ solution system changed from colorless to deep yellow, indicating that it reacted with Fe... 3+ In comparison, probe 1 for Cu 2+ The identification and binding are stronger, and the experimental phenomena and the calculated results of the complexation constant can corroborate each other. Because probe 1 identifies Cu... 2+ or Fe 3+ Afterwards, different color changes are visible to the naked eye, thus making it easy to distinguish between the two.

[0044] Example 6 This embodiment tested the pH-adjusting probe 1-Cu. 2+ and probe 1-Fe 3+ The effect of fluorescence intensity.

[0045] Test results are as follows Figure 7 As shown in cd, probe 1 is protonated in an acidic environment, rendering it unusable for recognizing metal ions; it is deprotonated in an alkaline environment, making probe 1 more stable and exhibiting stronger fluorescence intensity; however, in a strongly alkaline environment, Cu... 2+ Cu(OH)₂ precipitate was formed, Fe 3+ Fe(OH)3 precipitate was formed, preventing probe 1 from recognizing Cu in an alkaline environment. 2+ and Fe 3+ Therefore, probe 1 identifies Cu. 2+ and Fe 3+ The optimal pH range is pH=6~13 and pH=6~10.

[0046] Example 7 This embodiment tested probe 1 against Cu. 2+ and Fe 3+ Response time.

[0047] The test steps are as follows: First, add 3 mL of solvent to the cuvette, then add 3 μL of 10 mM probe solution, and then add 30 μL of 10 mM analyte ion. Test the change trend of fluorescence intensity with reaction time within 3 min.

[0048] Test results are as follows Figure 7 As shown in ef, in the absence of metal ions, the fluorescence intensity of probe 1 solution is stable and does not change over time; with the addition of Cu... 2+ or Fe 3+ Subsequently, the fluorescence intensity of the probe complex rapidly decreased, reaching its peak after approximately 60 seconds, and then tended to stabilize. The test results show that probe 1 is effective against Cu... 2+ or Fe 3+ All of them are characterized by rapid detection.

[0049] Example 8 This embodiment tested the binding characteristics of the probe to metal ions.

[0050] The testing procedure was as follows: The UV-Vis absorption spectra from 200 to 800 nm were recorded using a UV-Vis spectrophotometer (UV-3900). Fluorescence spectra were recorded using a HORIBA fluorescence spectrometer. The solvent used for photophysical measurements was a spectrally pure reference material. A comparative method was employed to determine the fluorescence quantum yield of the probe and the complex after recognizing the metal ions.

[0051] Test results are as follows Figure 8 As shown in the figure, the final result is obtained by substituting the slope shown in the figure and the reference fluorescence quantum yield into the formula.

[0052] ΦS = ΦR×(GS / GR)×(ηS / ηR) 2 Wherein, ΦS: fluorescence quantum efficiency of the sample to be tested; ηS: refractive index of the sample solution to be tested; GR: slope of the standard curve of the sample to be tested; ΦR: fluorescence quantum efficiency of the standard; ηR: refractive index of the standard solution; GR: slope of the standard curve of the standard.

[0053] Using quinine sulfate in 0.1 M sulfuric acid solution as a reference (Φ=0.54), and plotting the integrated area of ​​the fluorescence emission spectrum against absorbance, the relative fluorescence quantum yield of probe 1 was calculated to be 0.0036, indicating that it can identify Cu. 2+ The relative fluorescence quantum yield was 0.0003, a decrease of 12-fold, and the recognition of Fe... 3+ The relative fluorescence quantum yield was 0.0030, a decrease of 1.2-fold, which also indicates that probe 1 is effective against Cu. 2+ It has a stronger recognition effect.

[0054] Experimental studies have revealed that probe 1 is sensitive to viscosity factors, and the fluorescence intensity increases with increasing viscosity. This is due to the dynamic rotational properties of the Schiff base imine bond (-C=N-).

[0055] Example 9 This embodiment investigates the binding sites and binding modes between the probe and metal ions.

[0056] Using a wet loading method, the sample before and after the probe binds to metal ions is smeared onto a potassium bromide slide for infrared spectroscopy testing.

[0057] The results of the infrared spectroscopy measurement are as follows: Figure 9 As shown, the comparison probe 1 binds to Cu 2+ (or Fe) 3+ Changes in spectral data before and after, probe 1 at 1597.53 cm⁻¹ -1 The sharp, high-intensity peaks are attributed to C=N bond stretching vibrations; in identifying Cu... 2+ Later, it was speculated that the probe was 1-Cu. 2+ The conjugated system enhances the activity of -N=N-, resulting in a concentration at 1121.84 cm⁻¹.-1 A distinct stretching vibration peak appears at this location. This is relevant in identifying Cu. 2+ (or Fe) 3+ After [the process], the force constant of the C=N bond decreases, and the vibrational modes are restricted, leading to a decrease in the molar absorptivity, manifested as a decrease in the absorption peak intensity; the restriction of vibrational modes also causes a significant broadening of the peak shape until it disappears. These results indicate that probe 1 interacts with Cu through the O atoms of C=O and the N atoms of C=N bonds. 2+ (or Fe) 3+ ( ) combined.

[0058] Example 10 This embodiment studies the electron cloud distribution of the probe.

[0059] The HOMO and LUMO orbitals of the probe molecule were simulated using Gaussian software.

[0060] The HOMO orbital electron cloud of probe 1 is distributed on the imine bond and dimethylaminocinnamaldehyde; the LUMO orbital electron cloud is mainly distributed throughout the entire probe molecule. Based on UV titration data, Job's plot experiments, infrared spectroscopy data, NMR titration data, and density functional theory calculations, the interaction between probe 1 and Cu was investigated. 2+ (or Fe) 3+ The binding mechanism of probe 1 and Cu was investigated. Firstly, a clear isoabsorption point was observed in the ultraviolet spectrum, indicating the formation of a complex. Secondly, Job's plot experiments showed that probe 1 binds to Cu... 2+ (or Fe) 3+ All of them are obtained through 1:1 complexation (see...) Figure 10 ); through infrared spectroscopy and nuclear magnetic resonance titration, it can be determined that probe 1 and Cu 2+ (or Fe) 3+ All of these involve the O atom of the C=O bond combining with the N atom of the Schiff base's C=N bond, and the N atom of the hydrazide combining with the metal ion. For example... Figure 11 As shown, before the addition of metal ions, probe 1 exhibits green fluorescence. After recognizing metal ions, due to the paramagnetic Cu... 2+ (or Fe) 3 + The fluorophore provides an empty orbital with suitable energy, acting as a highly efficient electron acceptor and enhancing the photoinduced electron transfer (PET) effect. Electrons from the excited-state fluorophore are directly transferred to the unpaired electron orbitals of the metal ion. This process is extremely efficient due to the low-barrier channels and spin exchange unique to paramagnetic ions, causing the excited-state energy to dissipate rapidly as heat, preventing fluorescence emission. Therefore, enhancing the electron transfer path from the fluorophore to the metal ion results in fluorescence quenching, forming a "turn-off" detection.

[0061] Example 11 In this embodiment, probe 1 is made into a portable test strip.

[0062] The test paper was immersed in the ethanol solution of probe 1 and then dried to obtain the dried test paper of probe 1.

[0063] Two drops of different cation solutions were added to the dry test paper of probe 1, and the fluorescence change of the filter paper was observed. The test results are as follows. Figure 12 As shown. Cu was added dropwise. 2+ Fe 3+ and Ru 3+ The test paper showed obvious quenching, while the test paper with other ions added did not show obvious color change compared with the test paper with probe 1. Combined with the color change under fluorescent light, the identified metal ions can be accurately distinguished.

[0064] The above description, in conjunction with specific embodiments, provides a detailed explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A Schiff base compound, characterized in that, It has the structure shown in Equation I: I。 2. The method for preparing Schiff base compounds as described in claim 1, characterized in that, Includes the following steps: It is obtained by reacting 4-dimethylaminocinnamaldehyde with 2-furanoylhydrazide.

3. The preparation method according to claim 2, characterized in that, The reaction temperature is 60~90 °C; and / or the reaction time is 2~6 h.

4. The application of the Schiff base compound as described in claim 1 in the preparation of fluorescent probes for ion detection, characterized in that, The ions include Cu 2+ and Fe 3+ .

5. The application according to claim 4, characterized in that, The Schiff base compounds specifically react with the ions, and the fluorescent probe undergoes fluorescence quenching under ultraviolet light excitation.

6. An ion detection test strip, characterized in that, The reaction medium includes a reaction medium paper and a fluorescent probe loaded on the reaction medium paper, wherein the fluorescent probe is a Schiff base compound as described in claim 1, and the ion includes Cu. 2+ and Fe 3 + .

7. The method for preparing the ion detection test strip as described in claim 6, characterized in that, Includes the following steps: The reaction medium paper is obtained by immersing it in a fluorescent probe solution and then drying it.

8. The preparation method according to claim 7, characterized in that, The fluorescent probe solution is obtained by dissolving the fluorescent probe in an organic solvent, wherein the organic solvent includes at least one of methanol, ethanol, acetone, and tetrahydrofuran.

9. A reagent kit, characterized in that, The apparatus includes a fluorescent probe, reaction medium paper, a solvent, and a UV detection lamp and / or a fluorescent lamp, wherein the fluorescent probe is a Schiff base compound as described in claim 1, and the solvent is used to dissolve the fluorescent probe; or, It includes ion detection test strips, fluorescent colorimetric cards, and ultraviolet detection lamps and / or fluorescent lamps, wherein the ion detection test strips are the ion detection test strips as described in claim 6.

10. The application of the kit as described in claim 9 in the detection of ions in food ingredients, medicinal materials, or aquatic environments, characterized in that, The ions include Cu 2+ and Fe 3+ .

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