Synthesis of Cobalt Compounds with Helical Structure and Their Application in Electrochemical Detection

Abstract

The invention discloses the synthesis of a cobalt compound with a helical structure and its application in electrochemical detection, and relates to the technical field of organic synthesis and electrochemical detection. The invention uses N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid as ligands to react with cobalt salts to obtain a zinc complex. When the cobalt complex is used for electrochemical detection of the antibiotic furazolidone, it exhibits good selectivity and anti-interference, a wide detection range, high thermal stability, pH stability (3-10) and sensitivity, and a minimum detection limit of 5×10 ‑10 mol / L(R 2 =0.982).

Description

Technical field:

[0001] The invention relates to the technical field of organic synthesis and electrochemical detection, and in particular to a cobalt compound with a spiral structure and a synthesis method thereof, and application thereof in electrochemical detection of the antibiotic furazolidone. Background technology:

[0002] Antibiotic pollution has always been a serious environmental problem, and people have been looking for various methods to detect antibiotics in the environment. Furazolidone (FZD) is a nitrofuran broad-spectrum antibiotic that is widely used as a feed additive to prevent and treat gastrointestinal infections caused by Escherichia coli and Salmonella. Although the half-life of furazolidone in animals is extremely short, the furazolidone metabolite 3-amino-2-oxazolidinone can bind to proteins in the body and exist in the body for a long time in the form of a conjugate, causing carcinogenic, teratogenic, mutagenic and other toxic effects on the animal body. Therefore, it is very important to detect furazolidone in food in real time. So far, people have adopted different strategies to detect antibiotics in the environment, but because the content of antibiotics in actual samples is often very low and the coexisting substances are complex, it is of great practical significance to establish a rapid, highly sensitive and highly selective antibiotic detection method.

[0003] Electrochemical methods have become one of the most popular technologies for detecting antibiotics due to their advantages of simplicity, safety, speed, low cost and low detection limit. Electrochemical detection of antibiotics is an alternative path, and some chemically modified electrodes are used to detect antibiotics. So far, people have been trying to use chemically modified electrodes to lower the detection limit of antibiotics, but the search for modified electrode materials will be the biggest challenge.

[0004] Coordination polymers (CPs) refer to metal-organic compounds of different dimensions formed by organic ligands and metal atoms through coordination bonds under the guidance of the self-assembly principle of crystal engineering. Coordination polymers not only have excellent performance but also the structure of the compound can be controlled. Therefore, coordination polymers have been rapidly developed in the field of new materials. At present, coordination polymers are mostly used in the fields of adsorption, separation, catalysis, fluorescence, magnetism, etc., and some metal-organic pore polymers are also used in the research of pollutant sensing in the environment. In particular, coordination polymers with active sites, such as compounds with active functional groups (-NH2, -NO3, -OH, -CF3, -Cl, -SH, -COOH) in the structure. Coordination polymers with active sites can quickly react with the target, which is mainly because the active sites can produce weak interactions with the target to make the detected object react with the compound. Therefore, using coordination polymers with active sites as electrode materials to construct electrochemical sensors can greatly increase the sensitivity of the electrode, amplify the detected electrical signals, reduce the detection limit of the target object, and have good selectivity. Summary of the invention:

[0005] The technical problem to be solved by the present invention is to provide a cobalt compound with a helical structure and a synthesis method thereof and application in the electrochemical detection of the antibiotic furazolidone, which exhibits good selectivity and anti-interference, a wide detection range, and high thermal stability, pH stability and sensitivity.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0007] One of the purposes of the present invention is to provide a method for synthesizing a cobalt compound, wherein N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid are used as ligands to react with cobalt salts to obtain a cobalt complex.

[0008] Preferably, the cobalt salt is cobalt nitrate or a hydrate thereof.

[0009] Preferably, the molar ratio of the cobalt salt to N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid is 1.5:1.5:1.

[0010] Preferably, the solvent of the reaction is a mixed solvent of anhydrous ethanol and distilled water, and the volume ratio of anhydrous ethanol to distilled water is (10-15):(1-2), preferably 15:2.

[0011] Preferably, the reaction temperature is 150° C. and the reaction time is 5 to 7 days.

[0012] Preferably, the pH value of the reaction is 7.0.

[0013] A second object of the present invention is to provide a cobalt compound having a helical structure obtained according to the aforementioned synthesis method.

[0014] The molecular formula of the cobalt compound is C 29 H 35 N5O6Co belongs to the monoclinic system, P21 / c space group, and the unit cell parameters are α=90°, β=114.466°(10), γ=90°, and Z=4.

[0015] The third object of the present invention is to provide the use of the aforementioned cobalt compound in the electrochemical detection of the antibiotic furazolidone.

[0016] The minimum detection limit of the electrochemical detection of the antibiotic furazolidone is 5×10 -10 mol / L(R 2 =0.982).

[0017] The beneficial effects of the present invention are as follows: the present invention uses N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid as ligands to react with cobalt salts to obtain a zinc complex, and the cobalt complex exhibits good selectivity and anti-interference when used for electrochemical detection of the antibiotic furazolidone, a wide detection range, high thermal stability, pH stability (3 to 10) and sensitivity, and a minimum detection limit of 5×10 -10 mol / L(R 2 =0.982). Description of the drawings:

[0018] Figure 1 is the coordination mode diagram of the cobalt complex;

[0019] Figure 2 Two helical structure diagrams of cobalt complexes;

[0020] Figure 3 The diagram is a parallel folded chain structure of a cobalt complex;

[0021] Figure 4 is the thermogravimetric curve of the cobalt complex;

[0022] Figure 5 is the scanning electron microscopy image of the modified electrode AuNPs / 1 / GCE;

[0023] Figure 6 Cyclic voltammetry curves obtained under different electrodes;

[0024] Figure 7 Cyclic voltammograms of AuNPs / 1 / GCE modified electrode in the presence of different concentrations of furazolidone and the relationship between peak current and furazolidone concentration (SWASV parameters: frequency 40 Hz, amplitude 20 mV, voltage increment 4 mV);

[0025] Figure 8 To modify the selectivity of electrode AuNPs / 1 / GCE for furazolidone (SWASV parameters: frequency 40 Hz, amplitude 20 mV, voltage increment 4 mV);

[0026] Fig. 9 To investigate the anti-interference property of the modified electrode AuNPs / 1 / GCE in the presence of furazolidone and other antibiotics (SWASV parameters: frequency 40 Hz, amplitude 20 mV, voltage increment 4 mV). Specific implementation method:

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0028] Example 1

[0029] Synthesis of cobalt complex (compound 1):

[0030] N,N′-2,4-pyridine-2,6-diaminopyridine (LN5, 38.0 mg, 0.15 mmol) and 1,3-adamantanedicarboxylic acid (H2ADC, 22.4 mg, 0.10 mmol) and Co(NO3)3·6H2O (43.6 mg, 0.15 mmol) were added to a reaction kettle, and then 15 mL of anhydrous ethanol and 2 mL of distilled water were added. The pH value was adjusted to 7.0 with sodium hydroxide solution. The reaction kettle was placed in an electric constant temperature blast drying oven, heated to 150°C, and allowed to react at a constant temperature for 6 days. The reaction was naturally cooled to room temperature, filtered, washed with ethanol, and naturally dried to obtain purple crystals with a yield of 52%. The chemical formula is [Co(LN5)(ADC)] n ·C2H5OH·H2O. IR(cm -1 ): 3204(v), 1632(m), 1497(v), 1354(m), 1242(v), 1174(m), 1045(v); 966(m), 859(v), 748(m), 715(m).

[0031] Example 2

[0032] Testing crystal structure and refinement:

[0033] Select compound 1 crystals, and select crystals with bright surface, regular shape and suitable size for X-single crystal diffraction experiment. Purify Mo-Kα rays (λ=0.07nm) with graphite monochromator at room temperature, and then scan the selected crystals. Sorting out the data obtained after crystal diffraction, importing into SHELXTL software, processing the data to obtain the crystal structure of the crystal. The crystal refinement is optimized, and the full matrix least squares method F is used. 2 Refinement: The anisotropic temperature factor, isotropic temperature factor, non-hydrogen atom coordinates and hydrogen atom coordinates of the crystal are corrected until convergence. During the refinement process, the SHELXL-97 program needs to be used to complete all calculations. The relevant crystallographic data of compound 1 are listed in Table 1.

[0034] Table 1 Crystal data of compound 1

[0035]

[0036]

[0037] Crystal structure description of compound 1:

[0038] like Figure 1 As shown, compound 1 contains a cobalt atom, and the cobalt atom is hexacoordinated and octahedral. One of the oxygen atoms comes from 1,3-adamantanedicarboxylic acid, the other two oxygen atoms come from another 1,3-adamantanedicarboxylic acid, and the three nitrogen atoms come from two N,N′-2,4-pyridine-2,6-diaminopyridines. In compound 1, one carboxyl group on 1,3-adamantanedicarboxylic acid is combined with the cobalt atom in a chelating mode, while the other carboxyl group is connected to the cobalt atom in a monocoordinate mode.

[0039] like Figure 2 As shown, there are two different helical patterns in compound 1, in which the cobalt atom forms a left-handed helical structure with 1,3-adamantanedicarboxylic acid, and the cobalt atom forms a right-handed helical structure with N,N′-2,4-pyridine-2,6-diaminopyridine.

[0040] like Figure 3 As shown, in compound 1, the ligand is connected to the cobalt atom to form a folded chain structure, and each chain is parallel to each other.

[0041] Stability of Compound 1:

[0042] like Figure 4As shown in the figure, the thermogravimetric curve starts to remain stable until it reaches 95°C, then the curve starts to decline, and a platform appears at 150°C, that is, from 95 to 150°C, the weight loss of the curve in this stage is 10.55%, which is the free ethanol molecules and water molecules (theoretical value is 10.56%); then it stabilizes at about 220°C, and then the framework collapses, that is, the organic matter decomposes. This shows that compound 1 can be stable to 220°C and has good thermal stability.

[0043] Example 3

[0044] Study on the electrochemical properties of compound 1:

[0045] Compound 1 was dissolved in anhydrous ethanol to prepare a solution, and the solution was then dropped onto a glassy carbon electrode (GCE) and dried naturally to obtain a modified electrode 1 / GCE.

[0046] The modified electrode 1 / GCE was immersed in a chloroauric acid solution, and then cyclic voltammetry was used to deposit gold nanoparticles. The number of deposited gold segments was 6, and then dried to obtain the modified electrode AuNPs / 1 / GCE.

[0047] from Figure 6 It can be seen that compared with the modified electrode 1 / GCE, the modified electrode AuNPs / 1 / GCE has better conductivity and is more suitable as an electrode.

[0048] from Figure 7 It can be seen that the modified electrode AuNPs / 1 / GCE has a strong affinity for furazolidone at 1×10 -6 ~5×10 -9 mol / L concentration range, and the minimum detection limit was 5×10 -10 mol / L(R 2 =0.982). This shows that the modified electrode AuNPs / 1 / GCE has a wide linear range and a low detection limit for furazolidone.

[0049] from Figure 8 It can be seen that the modified electrode AuNPs / 1 / GCE exhibits a strong electrochemical signal intensity for furazolidone, but the electrochemical signal intensity for other types of antibiotics is relatively weak, including nitrofurazone (NZF), nitrofurantoin (NFT), sulfadiazine (SDZ), sulfadimethoxine (SMZ), metronidazole (MDZ), ronidazole (RDZ), ornidazole (ODZ), dimetronidazole (TDZ), penicillin (PCL), florfenicol (FFC), and chloramphenicol (CAP). This shows that the modified electrode AuNPs / 1 / GCE has good selectivity for furazolidone.

[0050] from Fig. 9It can be seen that the electrochemical signal intensities of the modified electrode AuNPs / 1 / GCE for furazolidone and the combination of furazolidone and other types of antibiotics are similar, which shows that the modified electrode AuNPs / 1 / GCE exhibits good anti-interference when used for electrochemical detection of furazolidone.

[0051] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for synthesizing a cobalt compound, characterized in that: N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid are used as ligands to react with cobalt salts to obtain cobalt compounds; The molecular formula of the cobalt compound is C 29 H 35 N5O6Co, belongs to the monoclinic system, P21 / c space group, unit cell parameters are α = 90°, β = 114.466° (10), γ = 90°, Z = 4; The cobalt salt is cobalt nitrate or its hydrate; The molar ratio of the cobalt salt to N,N′-2,4-pyridine-2,6-diaminopyridine and 1,3-adamantanedicarboxylic acid is 1.5:1.5:1; The solvent of the reaction is a mixed solvent of anhydrous ethanol and distilled water, and the volume ratio of anhydrous ethanol to distilled water is (10-15):(1-2); The temperature of the reaction was 150°C.

2. The synthesis method according to claim 1, characterized in that: The volume ratio of the anhydrous ethanol to distilled water is 15:

2.

3. The synthesis method according to claim 1, characterized in that: The reaction time is 5 to 7 days.

4. The synthesis method according to claim 1, characterized in that: The pH of the reaction was 7.

0.

5. A cobalt compound having a helical structure prepared by the synthesis method according to any one of claims 1 to 4.

6. Use of the cobalt compound according to claim 5 in the preparation of a reagent for electrochemical detection of the antibiotic furazolidone.

7. The use according to claim 6, characterized in that: The minimum detection limit of the electrochemical detection of the antibiotic furazolidone is 5×10 -10 mol / L.

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