A 2-amino-5-substituted-1,3,4-oxadiazole pair for the recognition of Fe 3+ ​

Abstract

The application discloses a method for identifying Fe by using 2-amino-5-substituted-1, 3, 4-oxadiazole. 3+ The method comprises the following steps: firstly, preparing a 2-amino-5-substituted-1, 3, 4-oxadiazole solution to be detected; secondly, adding a metal cation solution into the solution to be detected; and thirdly, identifying Fe by naked eye observation and ultraviolet-visible absorption spectrum. 3+ The method has good selectivity for Fe 3+ , is not interfered by other ions, and can better identify and detect Fe in the environment. 3+ ​

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis and cation detection, and relates to a 2-amino-5-substituted-1,3,4-oxadiazole for Fe 3+ Identification. Background Technology

[0002] 1,3,4-Oxadiazoles are a class of five-membered heterocyclic aromatic compounds containing oxygen and nitrogen heteroatoms, primarily existing as products of hydrogen substitution at the 2 and 5 positions. Due to the unique molecular structure of 1,3,4-oxadiazoles, they possess unique biological and optical activities and have been widely used in pesticides, pharmaceuticals, and materials. Introducing the 1,3,4-oxadiazole ring into different compound structures can generate novel drugs or electroluminescent materials with specific activities. Therefore, the synthesis of oxadiazole derivatives has become one of the hot research topics.

[0003] In recent years, the development of molecular acceptors for the detection of metal ions has been a growing and attractive research area, as they play a significant role in almost every field. Fe 3+ Iron is an essential component of hemoglobin, myoglobin, cytochrome oxidase, and ribonucleotide reductase, contributing to DNA synthesis, oxygen transport, and neurotransmitter synthesis. Besides its biological significance, iron is also used in industrial production as a catalyst in chemical reactions, agriculture, food, and nutrition. Iron ions are the most abundant transition metal in cells, playing a prominent biological role in oxygen absorption, oxygen metabolism, electron transfer, and transcriptional regulation. The high sensitivity and selectivity of iron ion detection are crucial for studying its physiological functions in organisms.

[0004] Oxadiazoles contain a –C=N- active group that binds to various metal ions, which is largely responsible for their numerous applications. Furthermore, their synthesis is relatively simple, and many methods for detecting Fe have been reported. 3+ Chemical sensors for metal ions, such as aminourea, are effective metal chelating agents and are widely used in probes. They have important application value in chemical sensors for metal ions and have become a research hotspot in recent years. Summary of the Invention

[0005] To overcome the shortcomings of some existing technologies, such as low sensitivity to adsorbed cations, a chromophore is introduced, allowing ions to be distinguished by visual color changes. The purpose of this invention is to provide a 2-amino-5-substituted-1,3,4-oxadiazole for Fe... 3+ Identification.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for detecting iron ions, characterized by comprising the following steps:

[0008] Step 1) Prepare a 2-amino-5-substituted-1,3,4-oxadiazole solution to obtain the test solution;

[0009] Step 2) Prepare the cation solution:

[0010] The cation solution and the test solution are mixed to obtain the test solution. The color change of the test solution is observed, and the presence of iron ions in the cation solution is identified based on the color change of the test solution.

[0011] Furthermore, 2-amino-5-substituted-1,3,4-oxadiazole is as shown in formula (1).

[0012]

[0013] Wherein, R is H, 4-CH3, 4-OCH3, 4-OH, 4-NO2, 4-Cl, 4-F, 4-Br, 2-CH3, 2-OH, 2-NO2, 3-NO2, 3-Cl, 3-Br

[0014] Furthermore, the cation is Al. 3+ Sn 2+ ,Zn 2+ Cu 2+ ,Mn 2+ ,Fe 2+ Li + Ca 2+ ,K + ,Fe 3+ Co 2+ ,La 3+ Ho 3+ ,Pb 2+ ,Bi 3+ Ni 2+ .

[0015] Furthermore, when the cation solution and the test solution are mixed, the concentration of the cation solution is 1×10⁻⁶. -2 mol / L; the concentration of the test solution is 1×10⁻⁶. -4 mol / L.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This invention provides a 2-amino-5-substituted-1,3,4-oxadiazole for Fe 3+ Identification is achieved by the binding of the active -C=N- group in the synthesized 2-amino-5-substituted oxadiazole to different metal ions.

[0018] A 2-amino-5-substituted-1,3,4-oxadiazole for Fe 3+ For identification, a test solution of 2-amino-5-substituted-1,3,4-oxadiazole was prepared. A cation solution was added to the test solution, and Fe was identified by visual observation and UV-Vis absorption spectroscopy. 3 + It was found that it affects Fe 3+ It exhibits excellent selectivity, which is unaffected by other ions, and 2-amino-5-substituted-1,3,4-oxadiazole can better detect Fe in the environment. 3+ . Attached Figure Description

[0019] Figure 1 UV-Vis absorption spectra of 2-amino-5-phenyl-1,3,4-oxadiazole in different solvents;

[0020] Figure 2 The UV-Vis absorption spectra of 2-amino-5-phenyl-1,3,4-oxadiazole dissolved in different proportions of (CH3OH:H2O);

[0021] Figure 3 Adding Fe to 2-amino-5-phenyl-1,3,4-oxadiazole 3+ UV-Vis absorption spectrum of ions;

[0022] Figure 4 2-Amino-5-phenyl-1,3,4-oxadiazole for Fe 3+ Specific identification;

[0023] Figure 5 The effect of pH on the addition of cations to 2-amino-5-phenyl-1,3,4-oxadiazole;

[0024] Figure 6 The effect of time on the addition of 2-amino-5-phenyl-1,3,4-oxadiazole to the cation;

[0025] Figure 7 2-Amino-5-phenyl-1,3,4-oxadiazole for Fe 3+ Quantitative testing; Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings:

[0027] Example 1: Solvent screening of 2-amino-5-phenyl-1,3,4-oxadiazole

[0028] 2-Amino-5-phenyl-1,3,4-oxadiazole was prepared into 1×10⁻⁶ solutions using CH₃OH, DMSO, CH₃CN, and DMF, respectively.- 4 A solution of mol / L was used to measure the ultraviolet-visible absorption spectrum. Figure 1 As can be seen from the data, the UV absorption intensity is significantly enhanced after the addition of CH3OH compared with other solvents. Therefore, CH3OH was chosen as the solvent to prepare 2-amino-5-phenyl-1,3,4-oxadiazole.

[0029] Example 2: Screening of 2-amino-5-phenyl-1,3,4-oxadiazole against different ratios of CH3OH and H2O

[0030] 2-Amino-5-phenyl-1,3,4-oxadiazole was prepared in the following formulations: (CH3OH:H2O = 10:0), (CH3OH:H2O = 8:2), (CH3OH:H2O = 6:4), (CH3OH:H2O = 5:5), (CH3OH:H2O = 4:6), and (CH3OH:H2O = 2:8) to a concentration of 1×10⁻⁶. -4 A solution of mol / L was used to measure the ultraviolet-visible absorption spectrum. Figure 2 As can be seen from the data, the UV absorption intensity of CH3OH:H2O = 5:5 is significantly enhanced compared to other ratios. Therefore, CH3OH:H2O = 5:5 is selected as the solvent to prepare 2-amino-5-phenyl-1,3,4-oxadiazole.

[0031] Example 3: 2-Amino-5-phenyl-1,3,4-oxadiazole against Fe 3+ "Naked eye" recognition

[0032] 2-Amino-5-phenyl-1,3,4-oxadiazole was dissolved in CH3OH:H2O at a ratio of 5:5 to prepare a solution with a concentration of 1×10⁻⁶. - 4 The test solution was prepared at mol / L and sonicated. AlCl3, SnCl2, ZnCl2, CuCl2·2H2O, MnCl2, FeCl2, LiCl, CaCl2·2H2O, KCl, FeCl3·6H2O, CoCl2·6H2O, La(NO3)3·6H2O, Ho(NO3)3·6H2O, Pb(NO3)2, NiSO4·6H2O, and Bi(NO3)3·5H2O were prepared with ultrapure water to a concentration of 1×10⁻⁶. -2 Prepare a mol / L cation solution for later use. Accurately pipette 3 mL of the 2-amino-5-phenyl-1,3,4-oxadiazole test solution into 17 sample tubes, reserving one sample tube as a blank control. Add 30 μL of each of the 16 test cation solutions to the remaining 16 test solutions using a pipette. Sonicate these 17 samples, allow them to stand to disperse evenly, and then observe the color change of 2-amino-5-phenyl-1,3,4-oxadiazole. Add Fe...3+ After ionization, the solution changes from colorless to yellow, and the color of the solution containing other cations is consistent with the color of the 2-amino-5-phenyl-1,3,4-oxadiazole test solution. This allows for the detection of Fe in the test sample. 3+ ion.

[0033] Example 4: 2-Amino-5-phenyl-1,3,4-oxadiazole against Fe 3+ Selective detection

[0034] 2-Amino-5-phenyl-1,3,4-oxadiazole was dissolved in CH3OH:H2O at a ratio of 5:5 to prepare a solution with a concentration of 1×10⁻⁶. - 4 The test solution was prepared by sonication at a concentration of mol / L. AlCl3, SnCl2, ZnCl2, CuCl2·2H2O, MnCl2, FeCl2, LiCl, CaCl2·2H2O, KCl, FeCl3, CoCl2·6H2O, La(NO3)3·6H2O, Ho(NO3)3·6H2O, Pb(NO3)2, NiSO4·6H2O, and Bi(NO3)3·5H2O were prepared with ultrapure water to a concentration of 1×10⁻⁶ mol / L. -2 Prepare a mol / L cation solution for later use. Accurately pipette 3 mL of the 2-amino-5-phenyl-1,3,4-oxadiazole test solution into 17 sample tubes, reserving one tube as a blank control. Add 30 μL of each of the 16 test cation solutions to the remaining 16 tubes using a pipette. Sonicate these 17 samples, allow them to stand to disperse evenly, and then measure the UV-Vis absorption spectrum of 2-amino-5-phenyl-1,3,4-oxadiazole. Figure 3 As can be seen from the addition of Fe 3+ The graph shows the addition of Fe after a redshift from 291 nm to 296 nm. 3+ Compared to other cations, Fe 3+ The increased UV absorption intensity indicates that 2-amino-5-phenyl-1,3,4-oxadiazole can selectively recognize Fe. 3+ ion.

[0035] Example 5 2-Amino-5-phenyl-1,3,4-oxadiazole against Fe 3+ Specific identification

[0036] 2-Amino-5-phenyl-1,3,4-oxadiazole was dissolved in CH3OH:H2O at a ratio of 5:5 to prepare a solution with a concentration of 1×10⁻⁶. - 4The test solution was prepared at mol / L and sonicated. AlCl3, SnCl2, ZnCl2, CuCl2·2H2O, MnCl2, FeCl2, LiCl, CaCl2·2H2O, KCl, FeCl3, CoCl2·6H2O, La(NO3)3·6H2O, Ho(NO3)3·6H2O, Pb(NO3)2, NiSO4·6H2O, and Bi(NO3)3·5H2O were prepared with ultrapure water to a concentration of 1×10⁻⁶. -2 Prepare a mol / L cation solution for later use. Accurately pipette 3 mL of the 2-amino-5-phenyl-1,3,4-oxadiazole test solution into 17 sample tubes, reserving one set as a blank control. Add 30 μL of the prepared cation solution to each of the remaining 16 2-amino-5-phenyl-1,3,4-oxadiazole test solutions using a pipette, and then add 30 μL of Fe2+ to each sample tube. 3+ The ions were dispersed by ultrasonic agitation of all solution samples, allowed to stand to ensure uniform dispersion, and then their ultraviolet spectra were measured. From Figure 4 As can be seen, the absorbance of the 16 cation solutions added was similar to that of the 2-amino-5-phenyl-1,3,4-oxadiazole test solution, except for Fe. 3+ The increased absorption intensity of the ions indicates that the 2-amino-5-phenyl-1,3,4-oxadiazole test solution can selectively recognize Fe. 3+ Ions; Fe was added again after adding a cationic solution to 2-amino-5-phenyl-1,3,4-oxadiazole. 3+ In ionic solutions, the absorption intensity is significantly enhanced, as can be seen from the graph. This indicates that 2-amino-5-phenyl-1,3,4-oxadiazole has a significant effect on Fe. 3+ The ions have specific recognition capabilities, and other cations do not interfere, making them applicable to practical detection.

[0037] Example 6: Application Study of 2-amino-5-phenyl-1,3,4-oxadiazole at Different pH Values

[0038] To verify the practical application capability of 2-amino-5-phenyl-1,3,4-oxadiazole at different pH levels, the absorption intensity of 2-amino-5-phenyl-1,3,4-oxadiazole at 291 nm was investigated under different pH conditions. Figure 5 As shown, the absorption intensity of 2-amino-5-phenyl-1,3,4-oxadiazole remained essentially constant in different pH environments from pH 2.0 to 12.0. The addition of Fe... 3+ Subsequently, the pH remained essentially constant within the range of 2.0-12.0. This pH range of 2.0-12.0 can be used to treat Fe... 3+ Ions were detected. The results indicate that Fe2+ can be effectively identified at pH 7. 3+ion.

[0039] Example 7 Kinetic Study of 2-Amino-5-phenyl-1,3,4-oxadiazole

[0040] To verify the practical application capability of 2-amino-5-phenyl-1,3,4-oxadiazole, the change in absorption intensity of 2-amino-5-phenyl-1,3,4-oxadiazole over time during detection was studied at room temperature. Figure 6 As shown, the absorption intensity of 2-amino-5-phenyl-1,3,4-oxadiazole at 291 nm decreased within 0-80 min. The addition of Fe... 3+ The absorption intensity then weakens within 0-80 minutes. However, it can be used to treat Fe within the 0-80 minute range. 3+ Ions are detected.

[0041] Example 8 Quantitative determination of 2-amino-5-phenyl-1,3,4-oxadiazole

[0042] Identifying metal ions Fe 3+ The effect of concentration on the UV performance of the probe is as follows: Figure 7 As the concentration of the recognized ions increases proportionally, when the Fe concentration is continuously increased... 3+ At a concentration in solution, the absorption intensity at 291 nm decreases. Furthermore, as we can see from the inset, when Fe... 3+ When the concentration decreased to 0.4 eq, the absorption intensity decreased relatively gradually, indicating that Fe 3+ The complexation ratio of 2-amino-5-phenyl-1,3,4-oxadiazole is 2:3.

[0043] This invention discloses a 2-amino-5-substituted-1,3,4-oxadiazole for Fe 3+ For identification, a metal cation solution is added to the test solution, and Fe is identified by visual observation and ultraviolet-visible absorption spectroscopy. 3+ It was found that it affects Fe 3+ It exhibits excellent selectivity, which is unaffected by other ions, and 2-amino-5-substituted-1,3,4-oxadiazole can better identify and detect Fe in the environment. 3+ .

Claims

1. A method for the identification of 2-amino-5-substituted-l,3,4-oxadiazoles by means of Fe 3+ characterized in that The method comprises the following steps: Step 1) preparing a 2-amino-5-substituted-1,3,4-oxadiazole solution to obtain a test solution; Step 2) preparing a cation solution: Mixing the cation solution and the test solution to obtain a detection solution, observing the color change of the detection solution, and identifying whether there is iron ion in the cation solution based on the color change of the detection solution; the 2-amino-5-substituted-1,3,4-oxadiazole is as follows: ； wherein, R is H, 4-CH3, 4-OCH3, 4-OH, 4-NO2, 4-Cl, 4-F, 4-Br, 2-CH3, 2-OH, 2-NO2, 3-NO2, 3-Cl, 3-Br.

2. A method for the identification of 2-amino-5-substituted-l,3,4-oxadiazoles to Fe 3+ characterized in that The cation is Al 3+ , Sn 2+ , Zn 2+ , Cu 2+ , Mn 2+ , Fe 2+ , Li + , Ca 2+ , K + , Fe 3+ , Co 2+ , La 3+ , Ho 3+ , Pb 2+ , Bi 3+ or Ni 2+ .

3. A method for the identification of 2-amino-5-substituted-l,3,4-oxadiazoles as Fe 3+ characterized in that The concentration of the cation solution is 1 x 10 -2 mol / L when mixed with the solution to be tested, and the concentration of the solution to be tested is 1 x 10 -4 mol / L.

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