Fluorescent probe for detecting iodide ions as well as preparation method and application of fluorescent probe

Abstract

The invention belongs to the technical field of ion detection, and particularly relates to a fluorescent probe for detecting iodide ions as well as a preparation method and application thereof. The fluorescent probe comprises 1, 3-diphenylbenzo [4, 5] imidazo [1, 2-alpha] pyrazine and copper ions, the 1, 3-diphenylbenzo [4, 5] imidazo [1, 2-alpha] pyrazine is taken as a fluorescent matrix substance, nitrogen atoms in the 1, 3-diphenylbenzo [4, 5] imidazo [1, 2-alpha] pyrazine structure and the copper ions form coordinate bonds, and under the action of a solvent, the 1, 3-diphenylbenzo [4, 5] imidazo [1, 2-alpha] pyrazine fluorescent probe is constructed. 2-[1, 2-alpha] pyrazine and a copper ion binary system are added, and the fluorescent probe is obtained. The fluorescent probe disclosed by the invention has specific recognition on iodide ions and can be used for directly observing and detecting the iodide ions. The lowest detection limit of the fluorescent probe on iodide ions is 6.64 mu M, and the fluorescent probe has the advantages of high sensitivity, good selectivity and simplicity and convenience in operation.

Description

Technical Field

[0001] The invention belongs to the technical field of ion detection, and in particular relates to a fluorescent probe for detecting iodine ions and a preparation method and application thereof. Background Art

[0002] Currently, the detection of some important anions has attracted great attention, mainly because these anions play crucial roles in both biology and chemistry. Therefore, more and more such anion chemical sensors have been developed.

[0003] Among the many anions, iodine ions play an extremely important role in a series of biological activities, such as neural activity, thyroid function, cell growth and brain activity. Insufficient iodine ions can lead to thyroid dysfunction, such as goiter, hypothyroidism and cretinism. For pregnant women, iodine ions are of great significance to the development of the fetus and the stability of thyroid function. On the contrary, excessive intake of iodine ions can lead to thyroid dysfunction, such as hyperthyroidism and autoimmune thyroiditis. Therefore, accurate measurement of iodine ion content can effectively prevent related thyroid diseases caused by insufficient and excessive iodine ions, which is particularly important for the development of chemical sensors for iodine ions.

[0004] Existing iodine ion detection methods mainly include titration, chromatography, electrochemical methods, etc., but these methods have the problems of complex operation, long detection time and high cost. The detection method based on fluorescent probe has attracted wide attention due to its high sensitivity and simple operation.

[0005] The prior art discloses a fluorescent probe for identifying iodine ions, a preparation method thereof, and an identification method thereof, with publication number 201810138206.9. In the authorized patent, the preparation method of the fluorescent probe includes: 1) dissolving 4-bromobenzaldehyde in ethanol to obtain product A; 2) dissolving 2-acetylpyridine, potassium hydroxide and ammonia water in ethanol to obtain product B; 3) reacting product A and product B, filtering the precipitate and recrystallizing it to obtain product C; 4) adding product C, 4-pyridineethylene, palladium acetate and triphenylphosphine to triethylamine for mixed reaction, dissolving the product in chloroform, spin-drying and recrystallizing it to obtain product D; 5) suspending 1,8-naphthalene diimide in a mixture of N,N-dimethylformamide and DMSO, adding sodium methoxide, stirring and standing, then adding 1,4-dibromobutane, filtering and recrystallizing the precipitate to obtain product E; 6) adding product D to N,N-dimethylformamide, adding product E, adding ether until a precipitate is precipitated, filtering and drying to obtain a probe. The method for identifying iodide ions using the probe is as follows: the probe is dissolved in a solvent, then diluted with the solvent to obtain a fluorescent reagent, and then the sample to be identified is added dropwise to the fluorescent reagent, and then fluorescence excitation is performed, and the fluorescence spectrum of the fluorescence excitation is tested to identify the iodide ions in the sample to be identified.

[0006] Chu Ranran published a paper on the design, synthesis and biological application of a novel reactive fluorescent probe for detecting iodine ions in organisms. In the paper, the HCy-OMe-Br probe was synthesized through the specific reaction of iodine ions and trans-dibromoolefins. The HCy-OMe-Br probe contains two bromine atoms, which leads to poor fluorescence quenching effect, affecting the accuracy of iodine ion detection. In addition, it is also easily interfered by other ions, resulting in inaccurate detection results.

[0007] The above-mentioned prior art method of using fluorescent probes to identify iodide ions is too complicated. In addition, there are deficiencies in selectivity and sensitivity during the iodide ion detection process. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a fluorescent probe for detecting iodine ions and a preparation method and application thereof.

[0009] As a common organic intermediate, benzimidazole compounds and their derivatives are widely used as pharmaceutical and pesticide intermediates due to their good biological activity. Since these substances have a rigid structure and good thermal stability, they are often used as ideal nonlinear optical materials and organic electroluminescent materials. Benzimidazole derivatives have good two-photon absorption ability and a quantum yield as high as 0.38. Compared with benzothiazole and benzoxazole derivatives, their luminescence performance is superior; in addition, benzimidazole derivatives containing benzimidazole functional groups have strong coordination ability because the nitrogen atoms in the structure can provide lone pairs of electrons.

[0010] The present invention uses 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine as a fluorescent matrix material. The full English name of 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine is 1,3-Diphenyl-benzo[4,5]imidazo[1,2-a]pyrazine, referred to as DBIP. Due to the special structure of DBIP, it can emit fluorescence of different colors when using different solvents. When ethanol is used as a solvent, DBIP emits blue fluorescence; when glacial acetic acid is used as a solvent, DBIP emits white fluorescence; when a mixed solvent of ethanol and glacial acetic acid is used, DBIP emits fluorescence of different colors under different volume ratios of ethanol and glacial acetic acid; the present invention explores the fluorescence color and fluorescence spectrum of DBIP under different solvents, selects a mixed solvent with a suitable volume ratio as the solvent of DBIP, and constructs a binary system fluorescent probe formed by DBIP and copper ions. In addition, DBIP has a longer conjugated chain and better luminescence performance. Its structure contains nitrogen atoms that can provide lone pairs of electrons, which can achieve coordination with copper ions. Then, with the help of the redox reaction between copper ions and iodide ions, selective detection of iodide ions can be achieved.

[0011] The first object of the present invention is to provide a fluorescent probe for detecting iodine ions.

[0012] The present invention uses DBIP as a fluorescent matrix material, forms a coordination bond through the lone pair of electrons provided by the nitrogen atom in the DBIP structure and the empty orbital provided by the copper ion, and constructs a binary system fluorescent probe composed of DBIP and copper ions under the action of a solvent. Then, the redox reaction between the copper ion and the iodine ion is used to interrupt the coordination between DBIP and the copper ion, thereby realizing the specific recognition of the iodine ion.

[0013] A second object of the present invention is to provide a method for preparing the fluorescent probe for detecting iodine ions, comprising the following steps:

[0014] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0015] The present invention explores the influence of solvents on the fluorescence spectrum of DBIP solution. Different solvents have different polarities. As the polarity of the solvent increases, it will have a greater stabilizing effect on the excited state, causing the energy of the excited state to decrease, thereby reducing the transition energy from the excited state to the ground state, causing the fluorescence wavelength of the substance to red shift and the fluorescence intensity to increase. Since the polarity of ethanol is less than that of glacial acetic acid, when the solvent of the DBIP solution is ethanol, the position of its emission peak is 469nm, emitting blue fluorescence; when the solvent of the DBIP solution is changed to glacial acetic acid, the position of its emission peak changes to 443nm and 541nm, emitting white fluorescence; when the solvent of the DBIP solution is a mixed solvent containing ethanol, its emission peak will blue shift, that is, the position of the emission peak becomes smaller; that is, the difference in solvents will cause the position of the emission peak of the DBIP solution to change, thereby changing the color of the fluorescence emitted. When the volume ratio of ethanol to acetic acid is 1:1, the emission peak position of the DBIP solution has changed: from 469nm to 441nm, and as the volume ratio of acetic acid increases, the fluorescence peak of 541nm begins to appear clearly, and the relative intensity becomes stronger and stronger. When the volume ratio of ethanol to acetic acid is 1:9, the DBIP solution begins to show obvious white fluorescence. The present invention selects a mixed solution of ethanol and acetic acid as the solvent of the DBIP solution. In a preferred embodiment of the present invention, the volume ratio of ethanol to acetic acid is 1:9 to 39.

[0016] It should be noted that, since the concentration of the prepared DBIP solution is extremely low, direct preparation is not possible. Therefore, a DBIP solution with a higher concentration is first prepared, and then the DBIP solution with the higher concentration is diluted to a DBIP solution with a desired concentration, thereby preparing a low-concentration DBIP solution. In a preferred embodiment of the present invention, the concentration of the DBIP solution is 2×10 -5 M.

[0017] Step 2: Add soluble copper salt to the DBIP solution to obtain a fluorescent probe.

[0018] It should be noted that the interaction between metal ions and DBIP solution plays an important role in the formation of fluorescent probes. By exploring the effect of metal ions on the fluorescence intensity of DBIP solution, the interaction between metal ions and DBIP solution is further analyzed. Since the lone electron pairs provided by nitrogen atoms in the DBIP structure in the DBIP solution form coordination bonds with the empty orbitals provided by copper ions, the DBIP in the DBIP solution has a strong coordination effect with copper ions. Preferably, the soluble copper salt is one of copper nitrate, copper chloride or copper sulfate. Preferably, the molar ratio of the DBIP solution to the soluble copper salt is 1:2.5-5.

[0019] In addition, since the DBIP solution prepared in the present invention is colorless under visible light and white fluorescence under ultraviolet light, when copper ions are added to the DBIP solution, the fluorescence of the fluorescent probe of the binary system constructed by DBIP and copper ions becomes blue fluorescence, so that the copper ions can be directly observed under ultraviolet light that they have been added. In other words, by using ultraviolet light, it can be directly observed that the binary system fluorescent probe of DBIP and copper ions has been successfully prepared, and the fluorescent probe prepared in the present invention is a liquid fluorescent probe.

[0020] The third object of the present invention is to provide the use of the above-mentioned fluorescent probe for detecting iodine ions in detecting iodine ions.

[0021] Preferably, the method for detecting iodide ions is:

[0022] The solution to be tested is added into the colorless and transparent fluorescent probe, and mixed evenly to obtain a test solution.

[0023] The color change of the test solution was observed under visible light.

[0024] When the color of the test solution does not change, it means that the test solution does not contain iodide ions.

[0025] When the color of the test solution changes from colorless to yellow, it indicates that the test solution contains iodide ions.

[0026] Alternatively, under ultraviolet light, the fluorescence of the test solution is quenched, indicating that the test solution contains iodide ions.

[0027] Preferably, the volume ratio of the fluorescent probe to the solution to be tested is 1 to 1.5:1.

[0028] Preferably, the minimum detection limit of the iodide ion is 6.64 μM.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The fluorescent probe of the present invention includes DBIP and copper ions. The fluorescent probe of the present invention uses DBIP as a fluorescent matrix material, and forms a coordination bond through the lone pair of electrons provided by the nitrogen atom in the DBIP structure and the empty orbital provided by the copper ion, so that DBIP and the copper ion have a strong coordination effect, and a binary system of DBIP and copper ions is constructed to obtain a fluorescent probe. DBIP, as a fluorescent substance, has a strong fluorescent signal on a fluorescence spectrophotometer, and then the redox reaction between the copper ion and the iodide ion in the fluorescent probe is used to interrupt the coordination effect between DBIP and the copper ion, so as to achieve specific recognition of iodide ions. In addition, the solution to be tested is added to the colorless and transparent fluorescent probe, and mixed evenly to obtain a test solution; under visible light, by observing the color change of the test solution, when the color of the test solution does not change, it indicates that the test solution does not contain iodide ions; when the color of the test solution changes from colorless to yellow, it indicates that the test solution contains iodide ions; or, under ultraviolet light, the fluorescence of the test solution is quenched, indicating that the test solution contains iodide ions. The fluorescent probe prepared by the invention can detect iodine ions by direct observation under visible light and ultraviolet light.

[0031] The fluorescent probe of the present invention has the advantages of high sensitivity, good selectivity, simple operation and small sample usage. In addition, the response of the fluorescent probe of the present invention to iodine ions is linear between 0M and 200M, and the linear equation is Y=549.878-1.87639X, wherein X is the concentration of the iodine ion solution, and Y is the fluorescence intensity of the fluorescent probe system at 441nm under an excitation wavelength of 380nm. The minimum detection limit of the fluorescent probe of the present invention to iodine ions is 6.64μM, and can be used to construct a sensor for detecting the content of iodine ions. The DBIP and copper ion binary system fluorescent probe of the present invention has strong anti-interference to other anions and can be applied to the detection of iodine ions in actual samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a photograph of the DBIP solution of Examples 1 to 8 and Comparative Examples 2 to 6 under ultraviolet light, wherein Figure (a) is Example 2, Figure (b) is Example 3, Figure (c) is Example 4, Figure (d) is Example 1, Figure (e) is Example 5, Figure (f) is Example 6, Figure (g) is Example 7, Figure (h) is Example 8, Figure (i) is Comparative Example 2, Figure (j) is Comparative Example 3, Figure (k) is Comparative Example 4, Figure (l) is Comparative Example 5 and Figure (m) is Comparative Example 6.

[0033] Figure 2 1 is the fluorescence spectrum of the DBIP solution in Comparative Example 1 and Comparative Example 6 of the present invention.

[0034] Figure 3 1 is the fluorescence spectrum of the DBIP solution of Examples 1 to 2 and 5 to 8 of the present invention.

[0035] Figure 4 It is the fluorescence intensity of the fluorescent probes of Example 1 and Comparative Examples 7 to 20 of the present invention.

[0036] Figure 5 The fluorescence intensity changes of the fluorescent probe in Example 1 of the present invention under different anions are shown from left to right. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S 2- 、NO 3- 、SO3 2- and C2O4 2- The fluorescence intensity.

[0037] Figure 6 Figures 1 to 2 are photos of the fluorescent probe in Example 1 of the present invention under visible light under different anions, wherein Figure (a) is the DBIP solution of Example 1, Figure (b) is the fluorescent probe of Example 1, and Figures (c) to (n) are photos of the fluorescent probe of Example 1 with I added sequentially. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S 2- 、NO 3- 、SO3 2- and C2O4 2- Photographs taken under visible light.

[0038] Figure 7 Figures 1 to 2 are photos of the fluorescent probe in Example 1 of the present invention under UV light under different anions, wherein Figure (a) is the DBIP solution of Example 1, Figure (b) is the fluorescent probe of Example 1, and Figures (c) to (n) are photos of the fluorescent probe of Example 1 with I added sequentially. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S2- 、NO 3- 、SO3 2- and C2O4 2- Photographs taken under visible light.

[0039] Figure 8 The fluorescence intensity of the fluorescent probe of Example 1 of the present invention at different iodine ion concentrations, and the iodine ion concentration gradually increases from top to bottom.

[0040] Fig. 9 These are photographs of the fluorescent probe of Example 1 of the present invention under visible light at different iodine ion concentrations, wherein Figure (a) is the DBIP solution of Example 1, and the iodine ion concentrations in Figures (b) to (h) are 0, 100 μM, 200 μM, 300 μM, 400 μM, 500 μM and 600 μM, respectively.

[0041] Fig.10 These are photographs of the fluorescent probe of Example 1 of the present invention under ultraviolet light at different iodine ion concentrations, wherein Figure (a) is the DBIP solution of Example 1, and the iodine ion concentrations in Figures (b) to (h) are 0, 100 μM, 200 μM, 300 μM, 400 μM, 500 μM and 600 μM, respectively.

[0042] Fig.11 This is a working curve of fluorescence intensity fitting of the fluorescent probe system of Example 1 of the present invention.

[0043] Fig.12 It is the fluorescence intensity of the fluorescent probe of Example 1 of the present invention in the coexistence of other anions and iodine ions.

[0044] Fig.13 These are photos of the fluorescent probe with and without starch added in Example 1 of the present invention, wherein Figure (a) is a photo without starch added, and Figure (b) is a photo with starch added. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand that the technical solution of the present invention can be implemented, the present invention is further described below in conjunction with specific embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0047] The invention is further described below through specific examples.

[0048] It should be noted that the DBIP of the present invention is synthesized from 2-benzoylbenzimidazole using the synthesis method disclosed by Zhang Min's group, and DBIP is used as the fluorescent matrix material of the present invention to further explore the coordination effect between DBIP and metal ions, and construct a binary system of DBIP and copper ions to obtain a fluorescent probe. The present invention utilizes the redox reaction between iodine ions and copper ions to interrupt the coordination effect between DBIP and copper ions, thereby achieving specific recognition of iodine ions.

[0049] Example 1

[0050] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0051] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0052] 1.1) 20 mL of ethanol and 180 mL of glacial acetic acid were measured and mixed, and stirred to obtain a mixed solvent.

[0053] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0054] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0055] Example 2

[0056] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0057] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0058] 1.1) 5 mL of ethanol and 195 mL of glacial acetic acid were measured, mixed, and stirred to obtain a mixed solvent.

[0059] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0060] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0061] The difference between this embodiment and embodiment 1 is:

[0062] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:39.

[0063] Example 3

[0064] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0065] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0066] 1.1) 5 mL of ethanol and 145 mL of glacial acetic acid were measured, mixed, and stirred to obtain a mixed solvent.

[0067] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0068] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0069] The difference between this embodiment and embodiment 1 is:

[0070] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:29.

[0071] Example 4

[0072] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0073] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0074] 1.1) 10 mL of ethanol and 190 mL of glacial acetic acid were measured, mixed, and stirred to obtain a mixed solvent.

[0075] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10-5 M of DBIP solution.

[0076] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0077] The difference between this embodiment and embodiment 1 is:

[0078] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:19.

[0079] Example 5

[0080] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0081] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0082] 1.1) 40 mL of ethanol and 160 mL of glacial acetic acid were measured and mixed, and stirred to obtain a mixed solvent.

[0083] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0084] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0085] The difference between this embodiment and embodiment 1 is:

[0086] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:4.

[0087] Example 6

[0088] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0089] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0090] 1.1) 50 mL of ethanol and 150 mL of glacial acetic acid were measured, mixed, and stirred to obtain a mixed solvent.

[0091] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0092] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0093] The difference between this embodiment and embodiment 1 is:

[0094] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:3.

[0095] Example 7

[0096] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0097] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0098] 1.1) 60 mL of ethanol and 120 mL of glacial acetic acid were measured and mixed, and stirred to obtain a mixed solvent.

[0099] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0100] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0101] The difference between this embodiment and embodiment 1 is:

[0102] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:2.

[0103] Example 8

[0104] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0105] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0106] 1.1) 100 mL of ethanol and 100 mL of glacial acetic acid were measured, mixed, and stirred to obtain a mixed solvent.

[0107] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0108] Step 2: Add 10 μL of 2×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0109] The difference between this embodiment and embodiment 1 is:

[0110] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this embodiment is 1:1.

[0111] Example 9

[0112] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0113] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0114] 1.1) 20 mL of ethanol and 180 mL of glacial acetic acid were measured and mixed, and stirred to obtain a mixed solvent.

[0115] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0116] Step 2: Add 10 μL of 1×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0117] The difference between this embodiment and embodiment 1 is:

[0118] The concentration of copper nitrate in this embodiment is 1×10 -2 M.

[0119] Example 10

[0120] This embodiment provides a method for preparing a fluorescent probe for detecting iodine ions.

[0121] Step 1: dissolving DBIP in a solvent to obtain a DBIP solution.

[0122] 1.1) 20 mL of ethanol and 180 mL of glacial acetic acid were measured and mixed, and stirred to obtain a mixed solvent.

[0123] 1.2) Weigh 0.0643 g of DBIP and dissolve it in the above mixed solvent, and dilute it to 100 mL with the mixed solvent to obtain 2×10 -3 M DBIP solution was used as the stock solution. 20 μL of the stock solution was measured and dissolved in 1980 μL of the mixed solvent to obtain 2×10 -5 M of DBIP solution.

[0124] Step 2: Add 10 μL of 1.5×10 -2 M of copper nitrate to obtain a fluorescent probe.

[0125] The difference between this embodiment and embodiment 1 is:

[0126] The concentration of copper nitrate in this embodiment is 1.5×10 -2 M.

[0127] The solvents investigated in the present invention are ethanol and glacial acetic acid. By exploring the usage ratio of ethanol and glacial acetic acid, the influence of the solvent on the DBIP fluorescence spectrum and the luminescent color of the DBIP solution is further explored.

[0128] Comparative Example 1

[0129] This comparative example provides a method for preparing a DBIP solution.

[0130] Weigh 0.0643 g of DBIP and dissolve it in glacial acetic acid. Then use glacial acetic acid to make the DBIP solution dilute to 100 mL to obtain 2×10 -3 M of DBIP solution was used as the stock solution; 20 μL of the stock solution was measured and dissolved in 1980 μL of glacial acetic acid to obtain a DBIP solution.

[0131] The difference between this comparative example and Example 1 is:

[0132] The solvent of this comparative example is glacial acetic acid.

[0133] Comparative Example 2

[0134] This comparative example provides a method for preparing a DBIP solution.

[0135] The difference between this comparative example and Example 1 is:

[0136] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this comparative example is 6:4.

[0137] Comparative Example 3

[0138] This comparative example provides a method for preparing a DBIP solution.

[0139] The difference between this comparative example and Example 1 is:

[0140] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this comparative example is 7:3.

[0141] Comparative Example 4

[0142] This comparative example provides a method for preparing a DBIP solution.

[0143] The difference between this comparative example and Example 1 is:

[0144] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this comparative example is 8:2.

[0145] Comparative Example 5

[0146] This comparative example provides a method for preparing a DBIP solution.

[0147] The difference between this comparative example and Example 1 is:

[0148] The volume ratio of ethanol to glacial acetic acid in the mixed solvent of this comparative example is 9:1.

[0149] Comparative Example 6

[0150] This comparative example provides a method for preparing a DBIP solution.

[0151] The difference between this comparative example and Example 1 is:

[0152] The mixed solvent of this comparative example is ethanol.

[0153] Figure 1 The following are photos of the DBIP solutions of Examples 1 to 8 and Comparative Examples 2 to 6 under ultraviolet light, wherein Figure (a) is Example 2, Figure (b) is Example 3, Figure (c) is Example 4, Figure (d) is Example 1, Figure (e) is Example 5, Figure (f) is Example 6, Figure (g) is Example 7, Figure (h) is Example 8, Figure (i) is Comparative Example 2, Figure (j) is Comparative Example 3, Figure (k) is Comparative Example 4, Figure (l) is Comparative Example 5, and Figure (m) is Comparative Example 6. Figure 1It can be seen that as the volume of glacial acetic acid gradually decreases, the color of the light emitted by the DBIP solution changes from white light to bluish-purple light and then to blue light. That is to say, as the polarity of the mixed solvent becomes smaller and smaller, the color of the light emitted by the DBIP solution gradually changes from white light to blue light. White light is selected as the starting point. When a soluble copper salt solution is added, the DBIP solution emits blue light, that is, with the help of an ultraviolet lamp, it can be directly observed that the fluorescent probe required for measuring iodine ions is successfully prepared. When the volume ratio of ethanol to glacial acetic acid is 1:9, obvious white light begins to be observed. The preferred volume ratio of ethanol to glacial acetic acid of the present invention is 1:9 to 39, and the more preferred volume ratio of ethanol to glacial acetic acid is 1:9 as a solvent.

[0154] The invention investigates the influence of ethanol and glacial acetic acid as solvents respectively and the mixed solvent of ethanol and glacial acetic acid on the fluorescence spectrum of DBIP solution. Figure 2 is the fluorescence spectrum of DBIP solution in Comparative Example 1 and Comparative Example 6. Figure 2 It can be seen that when the solvent is ethanol, the emission peak position of the DBIP solution is 469nm; when the solvent is glacial acetic acid, the emission peak position of the DBIP solution is 443nm and 541nm. The increase in the polarity of the solvent will have a greater stabilizing effect on the excited state, causing the energy of the excited state to decrease, thereby reducing the transition energy from the excited state to the ground state, causing the fluorescence wavelength of the substance to red shift and the fluorescence intensity to increase. Since the polarity of ethanol is less than that of glacial acetic acid, when the solvent in the DBIP solution gradually changes to a mixed solvent containing ethanol, its emission peak will blue shift, that is, the emission peak position will become smaller.

[0155] Figure 3 is the fluorescence spectrum of the DBIP solution in Examples 1 to 2 and 5 to 8. Figure 2 and Figure 3 It can be seen from the combination that when the volume ratio of ethanol and glacial acetic acid is 1:1, the emission peak position of the DBIP solution has changed: from 469nm to 441nm, and as the volume of glacial acetic acid increases, the fluorescence peak of 541nm begins to appear, and the relative intensity of the fluorescence peak becomes stronger and stronger.

[0156] The effect of metal ions and DBIP plays an important role in the formation of fluorescent probes. By exploring the influence of metal ions on the fluorescence intensity of DBIP, the relationship between metal ions and DBIP is further analyzed to optimize the measurement results of iodine ions. The fluorescence intensity of the system at 443nm is determined by selecting an excitation wavelength of 380nm, where 1 is the fluorescence intensity of the fluorescent probe in Example 1, and 10 is the fluorescence intensity of the DBIP solution in Example 1.

[0157] Comparative Example 7

[0158] This comparative example provides a method for preparing a fluorescent probe.

[0159] The difference between this comparative example and Example 1 is:

[0160] This comparative example uses Al 3+ The solution was replaced with copper nitrate.

[0161] Comparative Example 8

[0162] This comparative example provides a method for preparing a fluorescent probe.

[0163] The difference between this comparative example and Example 1 is:

[0164] This comparative example uses Ca 2+ The solution was replaced with copper nitrate.

[0165] Comparative Example 9

[0166] This comparative example provides a method for preparing a fluorescent probe.

[0167] The difference between this comparative example and Example 1 is:

[0168] This comparative example uses Cd 2+ The solution was replaced with copper nitrate.

[0169] Comparative Example 10

[0170] This comparative example provides a method for preparing a fluorescent probe.

[0171] The difference between this comparative example and Example 1 is:

[0172] This comparative example uses Co 2+ The solution was replaced with copper nitrate.

[0173] Comparative Example 11

[0174] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0175] This comparative example uses Fe 2+ The solution was replaced with copper nitrate.

[0176] Comparative Example 12

[0177] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0178] This comparative example uses Hg 2+ The solution was replaced with copper nitrate.

[0179] Comparative Example 13

[0180] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0181] This comparative example uses K + The solution was replaced with copper nitrate.

[0182] Comparative Example 14

[0183] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0184] This comparative example uses Mg 2+ The solution was replaced with copper nitrate.

[0185] Comparative Example 15

[0186] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0187] This comparative example uses Mn 2+ The solution was replaced with copper nitrate.

[0188] Comparative Example 16

[0189] This comparative example provides a method for preparing a fluorescent probe. The difference between this comparative example and Example 1 is:

[0190] This comparative example uses Na + The solution was replaced with copper nitrate.

[0191] Comparative Example 17

[0192] This comparative example provides a method for preparing a fluorescent probe.

[0193] The difference between this comparative example and Example 1 is:

[0194] This comparative example uses Ni 2+ The solution was replaced with copper nitrate.

[0195] Comparative Example 18

[0196] This comparative example provides a method for preparing a fluorescent probe.

[0197] The difference between this comparative example and Example 1 is:

[0198] This comparative example uses Zn 2+ The solution was replaced with copper nitrate.

[0199] Comparative Example 19

[0200] This comparative example provides a method for preparing a fluorescent probe.

[0201] The difference between this comparative example and Example 1 is:

[0202] This comparative example uses Pb 2+ The solution was replaced with copper nitrate.

[0203] Comparative Example 20

[0204] This comparative example provides a method for preparing a fluorescent probe.

[0205] The difference between this comparative example and Example 1 is:

[0206] This comparative example uses Ag + The solution was replaced with copper nitrate.

[0207] Figure 4 is the fluorescence intensity of the fluorescent probe in Example 1 and Comparative Examples 7 to 20. Figure 4 It can be seen that different metal ions will correspondingly enhance the fluorescence intensity of DBIP in the fluorescent probe system. Compared with other metal ions, copper ions enhance the fluorescence intensity of DBIP in the fluorescent probe system most significantly. The addition of copper ions will coordinate with DBIP in the fluorescent probe system, thereby enhancing its rigid structure, thereby enhancing the fluorescence intensity. Since iodine ions can undergo redox reactions with copper ions, the coordination of DBIP and copper ions in the fluorescent probe system is weakened, thereby weakening the enhanced fluorescence intensity. In addition, the heavy atom effect of iodine element generated by the redox reaction of iodine ions and copper ions further weakens the fluorescence intensity of the fluorescent probe system, thereby achieving the detection of iodine ions. Comprehensive consideration of the present invention to prepare a fluorescent probe using copper ions and DBIP to construct a binary system.

[0208] Experimental testing

[0209] 1. Anion selective recognition

[0210] The present invention tests the fluorescence intensity change of the fluorescent probe in Example 1 on anions. 26 mL of the fluorescent probe in Example 1 is taken and divided into 13 portions, and then 4×10 -2 M of I - 、NO2 - 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S 2- 、NO3 - 、SO3 2- and C2O4 2- The solution was 20 mL each, and no anion was added to the blank group. The excitation wavelength was selected as 380 nm to measure the fluorescence intensity of the system at 441 nm. I is the fluorescence intensity of the fluorescent probe with anion added, and I0 is the fluorescence intensity of the fluorescent probe in the blank group. The results are shown in Figure 5 shown.

[0211] Figure 5 The fluorescence intensity changes of the fluorescent probe in Example 1 under different anions are shown from left to right. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S 2- 、NO 3- 、SO3 2- and C2O4 2- The fluorescence intensity of Figure 5 It can be seen that the addition of iodine ions has a great effect on the fluorescence quenching of the fluorescent probe, while the addition of other anions has almost no effect on the fluorescence intensity of the fluorescent probe.

[0212] Figure 6 Figures 1 to 2 are photos of the fluorescent probe in Example 1 under visible light under different anions, wherein Figure (a) is the DBIP solution of Example 1, Figure (b) is the fluorescent probe of Example 1, and Figures (c) to (n) are photos of the fluorescent probe of Example 1 with I added sequentially. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S 2- 、NO 3- 、SO3 2- and C2O4 2- Photographs taken under visible light. Figure 6 It can be seen intuitively from the photos that only when iodine ions are added to the fluorescent probe system, the color of the fluorescent probe turns yellow under visible light. When other anions are added to the fluorescent probe system, the color of the fluorescent probe hardly changes.

[0213] Figure 7 Figures 1 to 2 are photos of the fluorescent probe in Example 1 under UV light under different anions, wherein Figure (a) is the DBIP solution of Example 1, Figure (b) is the fluorescent probe of Example 1, and Figures (c) to (n) are photos of the fluorescent probe of Example 1 with I added to it in sequence. - 、NO 2- 、CO3 2- 、S2O3 2- , Cl - Br - 、F - , HS - , S2- 、NO3 - 、SO3 2- and C2O4 2- Photographed under ultraviolet light. Figure 7 It can be seen that under ultraviolet light irradiation, the fluorescence of the fluorescent probe system with iodine ions added is effectively quenched, while the fluorescent probe system with other anions added still has a fluorescent effect. It can be seen that the fluorescent probe system prepared by the present invention can selectively identify iodine ions and can detect iodine ions by direct observation.

[0214] 2. Effect of iodine ion concentration on fluorescent probe system

[0215] The present invention adds iodine ion solutions of different concentrations to the fluorescent probe of Example 1 to explore the effect of different concentrations of iodine ions on the fluorescence intensity of the fluorescent probe. Take 2 mL of the fluorescent probe of Example 1, select the excitation wavelength of 380 nm to measure the fluorescence intensity I of the system at 441 nm, and then add 2.5 μL of 4×10 -2 M of iodine ion solution, each time the corresponding fluorescence intensity is tested until the fluorescence of the fluorescent probe system is almost completely quenched. The results are as follows Figure 8 shown.

[0216] Figure 8 is the fluorescence intensity of the fluorescent probe of Example 1 at different iodine ion concentrations, and the iodine ion concentration increases gradually from top to bottom. Figure 8 It can be seen that as the concentration of iodine ions gradually increases, the fluorescence intensity of the fluorescent probe system gradually weakens. When the concentration reaches 450 μM, the fluorescence intensity of the fluorescent probe is quenched from the initial 530.72 to 27.239, and the quenching degree can reach 94.87%.

[0217] Fig. 9 These are photographs of the fluorescent probe of Example 1 under visible light at different iodine ion concentrations, wherein Figure (a) is the DBIP solution of Example 1, and the iodine ion concentrations in Figures (b) to (h) are 0, 100 μM, 200 μM, 300 μM, 400 μM, 500 μM and 600 μM, respectively. Fig. 9 It intuitively shows that as the concentration of iodine ions increases, the color of the fluorescent probe gradually changes from light blue to yellow under visible light.

[0218] Fig.10 The following are photos of the fluorescent probe of Example 1 under ultraviolet light at different iodine ion concentrations, wherein Figure (a) is the DBIP solution of Example 1, and Figures (b) to (h) have iodine ion concentrations of 0, 100 μM, 200 μM, 300 μM, 400 μM, 500 μM and 600 μM, respectively. Fig.10It can be seen that under ultraviolet light, the fluorescence of the fluorescent probe system decreases with the increase of iodine ion concentration until it is quenched. This indicates that with the increase of iodine ion concentration, the fluorescence of the fluorescent probe system prepared by the present invention can be completely quenched.

[0219] 3. Determination of the linear response range and minimum detection limit of iodide ions

[0220] The present invention performs a fluorescence intensity test of iodine ions on the fluorescent probe of Example 1. Take 2 mL of the fluorescent probe of Example 1, select an excitation wavelength of 380 nm to measure the fluorescence intensity of the system at 441 nm, as a blank control, measure 20 times and record the data to obtain the standard deviation of the blank control. Add iodine ions in equal amounts to the fluorescent probe so that the iodine ion concentrations are 0, 40 μM, 80 μM, 120 μM, 160 μM and 200 μM, respectively. Test the fluorescence intensity of iodine ions in the fluorescent probe system at concentrations of 0, 40 μM, 80 μM, 120 μM, 160 μM and 200 μM, respectively.

[0221] Fig.11 The working curve of the fluorescence intensity fitting of the fluorescent probe system in Example 1 under different concentrations of iodine ion solutions. Fig.11 It can be seen that the response of the method to iodine ions is linear between 0M and 200M, and the linear equation is Y=549.878-1.87639X, where X is the concentration of the iodine ion solution, Y is the fluorescence intensity of the fluorescent probe system at 441nm under an excitation wavelength of 380nm, and the linear correlation coefficient R=-0.99347. The standard deviation of the blank sample obtained by detecting the blank sample is 4.15407. By calculation, it is obtained that the minimum detection limit of the method for iodine ions is 6.64μM, indicating that the fluorescent probe prepared by the present invention has good selectivity and high sensitivity.

[0222] 4. The coexistence of other anions interferes with iodide ions

[0223] The present invention tests the fluorescence intensity of iodine ions on the fluorescent probe of Example 1. Take 2 mL of the fluorescent probe of Example 1 and add iodine ions at a concentration of 4×10 -2 20 μL of iodine ion solution of 10 M was recorded as the test solution, and the excitation wavelength was selected as 380 nm to measure the fluorescence intensity I0 of the test solution system at 441 nm; 11 portions of the test solution were taken, and 4×10 -2 M C2O4 2- 、F - 、S2O3 2- , S 2- , HS - , Cl - 、CO3 2- 、NO3 - Br- 、SO3 2- and NO2 - 20 μL of anion was recorded as the test solution, and the excitation wavelength was selected as 380 nm to measure the fluorescence intensity I of the test solution system at 441 nm.

[0224] Fig.12 is the fluorescence intensity of the fluorescent probe of Example 1 when other anions coexist with iodine ions. Fig.12 It can be seen that the fluorescence intensity of I is almost unchanged compared with I0, indicating that when other anions are added to the fluorescent probe system containing iodine ions, there is no interference in the detection of iodine ions. Therefore, the fluorescent probe prepared by the present invention can be applied to the detection of iodine ions in actual samples.

[0225] 5. Preliminary study of experimental mechanism

[0226] The present invention investigates the mechanism of the fluorescent probe of Example 1. 4 mL of the fluorescent probe of Example 1 is taken and a concentration of 4×10 -2 40 μL of iodide ion solution of 100 M was added to obtain a mixed solution; the mixed solution was divided into two parts, one was used as a reference, and 200 μL of starch solution was added to the other part.

[0227] Depend on Fig.13 As can be seen in the middle figure (a), when an appropriate amount of starch solution is added to the fluorescent probe system without iodine ions, the color of the solution does not change significantly. Fig.13 As shown in the middle figure (b), when a proper amount of starch solution is added to the fluorescent probe system with iodine ions, the solution turns blue-black. Since iodine turns blue when it encounters starch solution, it means that after iodine ions are added to the fluorescent probe system, they undergo a redox reaction with copper ions to produce iodine. Iodine has a heavy atom effect, which gradually weakens the fluorescence intensity of the fluorescent probe until it is quenched.

[0228] In the fluorescent probe prepared by the present invention, copper ions have the most obvious effect on enhancing the fluorescence intensity of DBIP, that is, copper ions have the strongest coordination effect with DBIP. When iodine ions are added to the fluorescent probe system, the solution turns blue obviously. Since iodine element will turn blue when it encounters starch solution, it indicates that iodine ions and copper ions undergo redox reaction in the fluorescent probe system to produce iodine element. Iodine element has a heavy atom effect, which gradually weakens the fluorescence intensity of the fluorescent probe until it is quenched, thereby realizing the detection of iodine ions.

[0229] From the perspective of fluorescence intensity, the fluorescent probe prepared by the present invention has a great degree of fluorescence quenching in the fluorescent probe when iodine ions are added, while the addition of other anions has almost no effect on the fluorescence intensity of the fluorescent probe. From the perspective of the fluorescence of the fluorescent probe, in the fluorescent probe system with other anions added, the fluorescent probe still has a fluorescence effect. This shows that the fluorescent probe system prepared by the present invention can selectively identify iodine ions and has good selectivity.

[0230] The fluorescent probe prepared by the present invention changes the color of the fluorescent probe from colorless to yellow under visible light only when iodine ions are added to the fluorescent probe system, and other anions will not produce this effect. Alternatively, under ultraviolet light irradiation, it is found that the fluorescence of the fluorescent probe is effectively quenched, and other anions will not produce this effect. The fluorescent probe system prepared by the present invention can realize the detection of iodine ions. In addition, when other anions are added to the fluorescent probe to detect the iodine ion system, there is no interference with the detection of iodine ions, and other anions of the fluorescent probe prepared by the present invention have strong anti-interference.

[0231] The fluorescent probe prepared by the present invention has a linear response to iodine ions between 0M and 200M, and the linear equation is Y=549.878-1.87639X, wherein X is the concentration of the iodine ion solution, and Y is the fluorescence intensity of the fluorescent probe system at 441nm under an excitation wavelength of 380nm. The minimum detection limit of the fluorescent probe prepared by the present invention to iodine ions is 6.64μM, indicating that the fluorescent probe prepared by the present invention has high sensitivity.

[0232] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0233] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A fluorescent probe for detecting iodine ions, characterized in that: The fluorescent probe includes 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine and copper ions; The nitrogen atom in the 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine and the copper ion form a liquid binary system fluorescent probe composed of 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine and the copper ion through coordination and under the action of a solvent; The solvent is a mixed solvent of ethanol and glacial acetic acid.

2. The method for preparing a fluorescent probe for detecting iodine ions according to claim 1, characterized in that: The following steps are involved: dissolving 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine in a solvent to obtain a 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine solution; A soluble copper salt is added to a 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine solution to obtain a fluorescent probe.

3. The method for preparing a fluorescent probe for detecting iodine ions according to claim 2, characterized in that: The volume ratio of the ethanol to the glacial acetic acid is 1:9-39.

4. The method for preparing a fluorescent probe for detecting iodine ions according to claim 2, wherein: The molar ratio of the 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine to the soluble copper salt is 1:2.5-5.

5. The method for preparing a fluorescent probe for detecting iodine ions according to claim 2, characterized in that: The concentration of the 1,3-diphenylbenzo[4,5]imidazo[1,2-α]pyrazine solution is 2×10 -5 M.

6. Use of the fluorescent probe for detecting iodine ions as claimed in claim 1 in detecting iodine ions.

7. Use of the fluorescent probe for detecting iodine ions according to claim 6 in detecting iodine ions, characterized in that: The method for detecting iodide ions is: Add the solution to be tested into the colorless and transparent fluorescent probe and mix well to obtain a test solution; By observing the color change of the test solution under visible light; When the color of the test solution does not change, it indicates that the test solution does not contain iodide ions; When the color of the test solution changes from colorless to yellow, it indicates that the test solution contains iodide ions; Alternatively, under ultraviolet light, observe the fluorescence change of the test solution. When the fluorescence of the test solution is quenched, it indicates that the test solution contains iodide ions.

8. Use of the fluorescent probe for detecting iodine ions according to claim 7 in detecting iodine ions, characterized in that: The volume ratio of the fluorescent probe to the solution to be tested is 1 to 1.5:

1.

9. Use of the fluorescent probe for detecting iodine ions according to claim 7 in detecting iodine ions, characterized in that: The minimum detection limit of the iodide ion is 6.64 μM.

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