Halogenated metalloporphyrin-based preparation method and imidazole compound molecular recognition method thereof

Abstract

The invention discloses a preparation method of halogenated metalloporphyrin and a molecular recognition method of halogenated metalloporphyrin on imidazole compounds. Pyrrole and halogenated benzaldehyde are used as raw materials, halogenated phenyl porphyrin is synthesized through reflux in propionic acid, and then halogenated phenyl metalloporphyrin is formed through coordination with metal ions. The halogenated metalloporphyrin is applied to recognition of imidazole compound molecules through ultraviolet-visible spectrometry, the Q-band absorbance of the halogenated metalloporphyrin is reduced along with increase of the ligand concentration, and high-sensitivity recognition is achieved along with red shift of an axial complex characteristic peak. The method is simple and convenient to operate and remarkable in recognition effect, and can be widely applied to detection of imidazole compounds in the fields of environmental monitoring, food safety and biomedicine.

Description

Technical Field

[0001] The present invention belongs to the field of preparation and application of metal porphyrin compounds, and particularly relates to the preparation of halogenated metal porphyrins and their molecular recognition of imidazole compounds. Background Art

[0002] In many fields such as environmental monitoring, food safety, and biomedicine, nitrogen-containing compounds (such as imidazoles, amines, pyridines, etc.) play an indispensable and important role. For example, amine compounds are not only by-products of many industrial production processes but also key metabolites in organisms. Pyridine compounds are widely present in pesticides, pharmaceuticals, and chemical products. However, many nitrogen-containing compounds are toxic or carcinogenic. For example, imidazole compounds are often used as insecticides and fungicides in agriculture, which may cause soil and water pollution. Moreover, its biodegradability is relatively poor and may persist in the environment for a long time. Prolonged exposure to imidazole may produce toxic reactions in certain organisms, affecting their reproductive and survival abilities, thus affecting biodiversity. Therefore, the development of efficient and sensitive detection technologies is crucial for maintaining the environment and ensuring human health. As a key component in the metabolic process of living organisms, porphyrin is known as the "vital pigment". The central metal ion, four meso positions, and eight positions of the four pyrrole rings can all serve as active sites for molecular recognition. Especially metal porphyrin derivatives (such as zinc porphyrin), due to the coordination ability of their central metal, can specifically interact with nitrogen-containing compounds and show broad application potential in the fields of molecular recognition, photocatalysis, biomedical imaging, etc. Although there have been many studies on the synthesis and application of metal porphyrins, there are few systematic studies on halogenated metal porphyrins in the recognition of nitrogen-containing compounds. Therefore, the synthesis of halogenated metal porphyrins and the systematic exploration of their recognition performance for nitrogen-containing compounds are of great significance for designing highly efficient and selective chemical sensors. Summary of the Invention

[0003] The present invention aims to provide a method for the preparation of halogenated metal porphyrins and their molecular recognition of imidazole compounds. To this end, the present invention synthesizes halogenated metal porphyrins, which can well recognize imidazole, 1-acetylimidazole, benzimidazole, 2-methylimidazole, and have broad application prospects in the fields of environmental monitoring and life science.

[0004] The present invention provides the following technical solutions: The present invention provides a preparation method of the above-mentioned halogenated metal porphyrins. Using pyrrole and halogenated benzaldehyde as raw materials, refluxing in propionic acid to synthesize halogenated porphyrins, and then coordinating with metal ions to form halogenated metal porphyrins. The synthesis process is as follows: wherein, M is Zn, Cu, Co, Fe; R1-R5 are one or more of halogen atoms (F, Cl, Br) and hydrogen atom H.

[0005] In the preparation, first, pyrrole was distilled by reduced pressure distillation for standby. Propionic acid and halogenated benzaldehyde were added to a flask, heated to reflux, and freshly distilled pyrrole was slowly dropped in. After addition, the mixture was refluxed for 20 minutes to 24 hours. Part of the solvent was removed by reduced pressure distillation, and the residue was cooled to room temperature with an ice-water bath, left to stand overnight, and a purple-black solid was precipitated. Then, through repeated column chromatography and rotary evaporation purification, halogenated porphyrin was obtained, and then coordinated with metal salt to form halogenated metal porphyrin.

[0006] The present invention also provides the method for molecular recognition of the above imidazole compounds. Using an ultraviolet-visible spectrophotometer with a wavelength range of 350 - 650 nm and a sealable glass cuvette. The host is halogenated metal porphyrin, and the guests are imidazole, 1-acetylimidazole, benzimidazole, and 2-methylimidazole. N,N-dimethylformamide (DMF) solutions with a certain accurate concentration of the host and different concentrations of the guests were prepared. After the reaction reached equilibrium, the change in the absorbance of the Q-band characteristic peak was measured. As the concentrations of imidazole, 1-acetylimidazole, benzimidazole, and 2-methylimidazole increased, the absorbance at the Q-band of the host halogenated metal porphyrin gradually decreased, and at the same time, a characteristic peak of an axial complex appeared, showing good molecular recognition effect.

[0007] Based on the above technical solutions, the present invention has the following beneficial effects: The method for molecular recognition of imidazole compounds based on halogenated metal porphyrin provided by the present invention is simple and easy to implement. The prepared halogenated metal porphyrin has good molecular recognition performance and can be applied to the detection and recognition of imidazole compounds in fields such as drug research and development and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is an ultraviolet isosbestic point diagram for implementing the molecular recognition of imidazole molecules with different concentrations by halogenated metal porphyrin. The abscissa is the wavelength, and the ordinate is the absorbance. Figure 2 It is an ultraviolet isosbestic point diagram for implementing the molecular recognition of 1-acetylimidazole molecules with different concentrations by halogenated metal porphyrin. The abscissa is the wavelength, and the ordinate is the absorbance. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] The present invention will be described in detail below with reference to the drawings. The following examples are only used to clearly explain the above technical solutions, but the scope of the above subject matter of the present invention is not limited to the following examples, and the protection scope of the present invention cannot be limited thereby.

[0010] Example 1

[0011] Add 70 mL of propionic acid and 10 mmol of p-bromobenzaldehyde into a two-necked flask, heat to reflux, add 10 mmol of freshly distilled pyrrole via a syringe. After addition, reflux for 40 min. Change the apparatus to a vacuum distillation apparatus to remove 30 mL of the solvent. Cool the residue to room temperature in an ice-water bath and let it stand overnight to precipitate a purple-black solid. The next day, centrifuge and separate the product, wash with methanol to obtain the crude product of tetra-(p-bromophenyl)porphyrin. Dissolve the crude product in a small amount of dichloromethane, load the sample by wet method, and purify using neutral Al2O3 as the filler (eluted with dichloromethane). Collect the purple band, rotary evaporate to remove the solvent to obtain purple crystals of tetra-(p-bromophenyl)porphyrin.

[0012] Add 5 mmol of halogenated porphyrin, 25 mmol of Zn(OAc)2, 15 mL of dichloromethane, and 8 mL of methanol solution into a 50 mL single-necked flask, and react at room temperature for 24 h. After the reaction, add distilled water for washing. Then extract with dichloromethane and dry over anhydrous sodium sulfate. Filter by suction, evaporate the filtrate to dryness, dissolve the residue in a small amount of dichloromethane, and separate by column chromatography (eluent: dichloromethane) to obtain the purple-red solid of tetra-(p-bromophenyl)zinc porphyrin.

[0013] Example 2 Add 5 mmol of tetra-(p-bromophenyl)porphyrin and 25 mmol of Co(OAc)2 into a 50 mL single-necked flask, add 15 mL of N,N-dimethylformamide (DMF) solution, and reflux for 12 h. After the reaction, add distilled water for washing. Then extract with dichloromethane and dry over anhydrous sodium sulfate. Filter by suction, evaporate the filtrate to dryness, dissolve the residue in a small amount of dichloromethane, and separate by column chromatography (eluent: dichloromethane). Recrystallize with dichloromethane and methanol, freeze in the refrigerator overnight, filter by suction, and dry in vacuo to obtain tetra-(p-bromophenyl)cobalt porphyrin.

[0014] Example 3 Add 5 mmol of tetra-(p-bromophenyl)porphyrin and 25 mmol of FeCl2 into a 50 mL single-necked flask, add 15 mL of N,N-dimethylformamide (DMF) solution, and reflux for 12 h. After the reaction, add distilled water for washing. Then extract with dichloromethane and dry over anhydrous sodium sulfate. Filter by suction, evaporate the filtrate to dryness, dissolve the residue in a small amount of dichloromethane, and separate by column chromatography (eluent: dichloromethane). Recrystallize with dichloromethane and methanol, freeze in the refrigerator overnight, filter by suction, and dry in vacuo to obtain tetra-(p-bromophenyl)iron porphyrin.

[0015] Example 4 Add 5 mmol of tetra-(p-bromophenyl)porphyrin, 25 mmol of Cu(OAc)₂, and 15 mL of N,N-dimethylformamide (DMF) solution to a 50 mL single-necked flask, and reflux for 12 h. After the reaction, add distilled water for washing. Then extract with dichloromethane and dry with anhydrous sodium sulfate. Filter by suction, evaporate the filtrate to dryness, dissolve the residue in a small amount of dichloromethane, and separate by column chromatography (eluent: dichloromethane). Recrystallize with dichloromethane and methanol, freeze in the refrigerator overnight, filter by suction, and dry under vacuum. Tetra-(p-bromophenyl)copper porphyrin is obtained.

[0016] Using DMF as the solvent, 10 solutions are prepared for each equilibrium constant measurement. In the same set of solutions, the concentration of the host solution is the same, while the concentration of the ligand solution is different. In this example, the concentration of the host haloporphyrin solution in each set of solutions is 6×10 -6 mol / L, and the concentration of the ligand solution varies in the range of 1×10 -5 ~5×10 -2 mol / L, and they are respectively: 1×10 -5 、5×10 -5 、1×10 -4 、5×10 -4 、1×10 -3 、5×10 -3 、1×10 -2 、5×10 -2 mol / L. In addition, the ligand concentrations in the other two solutions are 0 mol / L and an extremely large amount respectively.

[0017] Let the prepared solution stand for half an hour. After the reaction system reaches equilibrium, use a UV-visible spectrophotometer to measure the equilibrium absorbance value of the Q band of the haloporphyrin as the ligand concentration changes.

[0018] The absorbance changes after coordination with imidazole and 1-acetylimidazole are as shown in Figure 1 、 Figure 2 It can be observed that the position of the Q band absorption peak of the haloporphyrin undergoes a red shift, and a new peak gradually appears at about 10 nm after the red shift. This is the characteristic absorption peak of the axial coordination reaction. At the same time, a relatively clear isosbestic point can be observed, indicating that the haloporphyrin forms a complex with imidazole and 1-acetylimidazole, and it is a 1:1 complex. It shows good molecular recognition ability.

[0019] For the points in the technical scope claimed by the present invention where the point values are not exhausted, as well as the new technical solutions formed by the equivalent replacement of single or multiple technical features in the technical solutions of the embodiments, they are also within the scope claimed by the present invention; at the same time, in all the embodiments listed or unlisted in the present invention, the various parameters in the same embodiment only represent an example of its technical solution (i.e., a feasible solution), and there is no strict cooperation and limitation relationship between the various parameters. Among them, the various parameters can be replaced with each other when not violating the axioms and the requirements of the present invention, except as otherwise specially stated.

[0020] The technical means disclosed in the technical solution of the present invention are not limited to the technical means disclosed in the above technical means, but also include the technical solutions composed of any combination of the above technical features. The above is the specific implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A preparation method based on halogenated metal porphyrin and its molecular recognition method for imidazole compounds, characterized in that, The general structural formula (I) is as follows: wherein, M is Zn, Cu, Co, Fe; R1-R5 are one or more of halogen atoms (F, Cl, Br) and hydrogen atom H 。 2. According to claim 1, it is characterized in that The preparation method of the porphyrin is as follows: (1) Using pyrrole and halogenated benzaldehyde as raw materials, heating and refluxing in propionic acid to synthesize tetra-(halophenyl)porphyrin; (2) Coordinating the halophenylporphyrin obtained in step (1) with metal salt in an organic solvent to obtain halophenyl metal porphyrin.

3. The preparation method according to claim 2, wherein In step (1), the pyrrole is purified by vacuum distillation before use, the reaction temperature is the reflux temperature of propionic acid, and the reaction time is 20 minutes to 24 hours.

4. The preparation method according to claim 2, wherein The metal salt is zinc acetate, zinc chloride, copper acetate, copper chloride, cobalt acetate, cobalt chloride or hydrate of metal salt. The organic solvents used are one or a mixture of two or more of dichloromethane, chloroform, methanol, N,N-dimethylformamide. The reaction time is 20 minutes to 48 hours.

5. Use of a halogenated metal porphyrin prepared by the method according to any one of claims 1-4 in the molecular recognition of imidazole compounds, characterized in that, It includes the following steps: (1) Dissolving the halophenyl metal porphyrin in a solvent to prepare a host solution; (2) Adding imidazole compound solutions with different concentrations to the host solution and reacting until equilibrium; (3) Measuring the change in absorbance by ultraviolet-visible spectroscopy at 350-650 nm, and realizing the molecular recognition of imidazole compounds according to the relationship between the change in absorbance and the ligand concentration.

6. The application according to claim 5, wherein The solvent is dichloromethane, N,N-dimethylformamide, and the concentration of the main solution is 1×10 -4 -1×10 -8 mol / L.

7. The application according to claim 5, wherein Molecular recognition of imidazole compounds by halometal porphyrin, and the imidazole compounds are imidazole, 1-acetylimidazole, benzimidazole, 2-methylimidazole.

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