Preparation method of double-ligand Cu-MOF for rapid screening and detection of glyphosate

Abstract

A preparation method of a double-ligand Cu-MOF material for rapid screening and detection of glyphosate mainly uses Cu < 2 + > as a metal central ion and 2-aminoisophthalic acid (AIA) and trimesic acid (H3BTC) as ligands, and a solvothermal synthesis method is adopted to synthesize the double-ligand Cu-AIA / BTC MOF material with a low fluorescent background. Due to the ligand-metal charge transfer (LMCT) effect and the photoinduced electron transfer (PET) effect between ligands, the fluorescence of the ligand AIA is almost completely quenched in the Cu-MOF (the quenching efficiency is 98%). After the glyphosate is added, the glyphosate competes with the ligand in the Cu-MOF, so that the MOF structure collapses, the ligand is released, and the fluorescence of the AIA is recovered. Under the optimal condition, the Cu-MOF nano probe has good linearity on the glyphosate concentration within the range of 0.1-100 [mu] M, and the detection limit is 33 nM. The Cu-MOF nano probe has the advantages of high sensitivity, good selectivity and capability of visually detecting glyphosate. In addition, Cu-MOF has been successfully applied to plant tissue imaging, rapid screening of glyphosate contaminated samples and sensitive detection of glyphosate in tea leaves and soil, which indicates that the nano probe has a wide application prospect.

Description

Technical Field

[0001] The invention relates to a method for preparing a dual-ligand Cu-MOF for plant tissue imaging, rapid screening and sensitive detection of glyphosate, and belongs to the technical field of environmental analysis. Background Art

[0002] Glyphosate is a highly effective and broad-spectrum organophosphorus herbicide that is widely used in weed control in agricultural production. With the expansion of the scope of glyphosate use and the increase in dosage, glyphosate enters the ecological environment through various pathways such as pesticide spraying, absorption and transfer by plant roots, surface runoff and erosion, destroying the original ecological environment structure. At the same time, glyphosate will also enter the human body through the food chain, which has potential carcinogenicity and genotoxicity to humans, and may damage the immune system and endocrine system, endangering human health. Therefore, it is very important to monitor the content of glyphosate in plants, soil and water (Sci TotalEnviron, 2020, 705, 135808; Chemosphere, 2022, 298, 134308; Water Res, 2013,47, 5110-5120). At present, the commonly used analytical methods for glyphosate are high performance liquid chromatography and gas chromatography, which have the advantages of high sensitivity and good accuracy. However, due to the lack of chromophores and fluorescent groups in glyphosate, its analysis process usually requires a complex derivatization process. Optical sensors have been developed for on-site rapid detection of glyphosate due to their advantages such as simple equipment and fast response speed, such as carbon quantum dots (CDs), metal organic frameworks (MOFs), and organic small molecule probes (Food Chem, 2023, 403, 134346; New J Chem, 2022, 46, 19808-19816; Talanta, 2021, 224, 121834). However, these probes have high fluorescence background or require Cu ions to react with the probes. 2+ As an intermediate quantitative detection substance, it is not conducive to the detection of trace glyphosate. In view of this, the present invention uses a dual ligand strategy to synthesize a dual ligand Cu-MOF material with low fluorescence background for rapid screening and detection of glyphosate in a fluorescence-on mode. Summary of the invention

[0003] The purpose of the present invention is to synthesize a metal organic framework material with low fluorescence background, which can quickly screen and detect glyphosate pesticides in the environment by fluorescence on-state, and can be used for imaging of glyphosate plant tissues. 2+The Cu-AIA / BTC MOF material with low fluorescence background was synthesized by solvothermal synthesis method with 2-aminoisophthalic acid (AIA) and trimesic acid (H3BTC) as the central metal ion. Due to the ligand-metal charge transfer (LMCT) and ligand-ligand photoinduced electron transfer (PET) effects, the fluorescence of the fluorescent substance 2-aminoisophthalic acid (AIA) in the Cu-MOF material was almost completely quenched. After adding glyphosate, due to the interaction between glyphosate and the central ion Cu 2+ The competitive coordination of Cu-MOF causes the structure of Cu-MOF to collapse, resulting in the release of the ligand and the recovery of the fluorescence of the AIA ligand, thereby rapidly detecting glyphosate in a fluorescence-on manner. The technical solution of the present invention is as follows: Weigh appropriate amounts of Cu(NO3)23H2O, 2-aminoisophthalic acid and trimesic acid, use N,N-dimethylformamide (DMF) as a solvent, and ultrasonically dissolve the above substances to obtain a clear solution.

[0004] The obtained clarified mixed solution was transferred to a reactor lined with 100 mL polytetrafluoroethylene. After the reactor was tightened repeatedly, it was placed in an electric constant temperature drying oven and heated at 90 °C for 24 to 48 hours.

[0005] After the reaction is completed and the reactor is naturally cooled to room temperature, it is washed several times with DMF and ethanol and vacuum dried at 60°C for 10 to 12 hours. After activation and drying, a dark blue solid powder is obtained, which is a non-luminescent dual-ligand Cu-MOF material.

[0006] Compared with the prior art, the present invention has the following advantages: No Cu required 2+ As an intermediate quantitative substance.

[0007] It has low fluorescence background (fluorescence quenching rate is up to 98%).

[0008] High sensitivity, the detection limit of glyphosate is 33nM.

[0009] It has good selectivity and anti-interference to glyphosate.

[0010] It can be used for imaging of glyphosate in plant tissues and rapid screening and detection of glyphosate in the environment. DETAILED DESCRIPTION Example

[0011] Weigh Cu(NO3)2 3H2O (0.4948 g, 2.1 mmol), 2-aminoisophthalic acid (0.316 g, 1.7 mmol) and trimesic acid (0.072 g, 0.34 mmol), add to 60 mL of DMF solvent, and dissolve by ultrasonic until the solution is clear. Transfer the obtained clear mixed solution to a reactor lined with 100 mL polytetrafluoroethylene. After the reactor is tightened repeatedly, place it in an electric constant temperature drying oven and heat it at 90 °C for 24 hours. After the reaction is completed and the reactor is naturally cooled to room temperature, use a centrifuge (8000 rpm, centrifugation for 5 min) to remove the substances that do not participate in the reaction in the upper clear liquid to obtain a dark blue solid in the lower layer. Wash the dark blue solid several times with DMF and anhydrous ethanol, respectively, and then dry it at 60 °C. The mixture was vacuum dried and activated in a vacuum drying oven at 60 °C for 12 hours to obtain a dark blue solid powder, namely the Cu-AIA / BTC MOF material. Example

[0012] Weigh Cu(NO3)2 3H2O (0.4948 g, 2.1 mmol), 2-aminoisophthalic acid (0.316 g, 1.7 mmol) and trimesic acid (0.072 g, 0.34 mmol), add them to 60 mL of DMF solvent, and dissolve them by ultrasonication until the solution is clear. The obtained clear mixed solution is transferred to a reactor lined with 100 mL polytetrafluoroethylene. After the reactor is tightened repeatedly, it is placed in an electric constant temperature drying oven and heated at 90 °C for 36 hours. After the reaction is completed and the reactor is naturally cooled to room temperature, a centrifuge (8000 rpm, centrifugation for 5 min) is used to remove the substances that do not participate in the reaction in the upper clear liquid to obtain a dark blue solid in the lower layer. The dark blue solid is washed with DMF and anhydrous ethanol for multiple times, and then dried at 60 °C. The mixture was vacuum dried and activated in a vacuum drying oven at 60 °C for 12 hours to obtain a dark blue solid powder, namely the Cu-AIA / BTC MOF material. Example

[0013] Weigh Cu(NO3)2 3H2O (0.4948 g, 2.1 mmol), 2-aminoisophthalic acid (0.316 g, 1.7 mmol) and trimesic acid (0.072 g, 0.34 mmol), add them to 60 mL of DMF solvent, and dissolve them by ultrasonication until the solution is clear. The obtained clear mixed solution is transferred to a reactor lined with 100 mL polytetrafluoroethylene. After the reactor is tightened repeatedly, it is placed in an electric constant temperature drying oven and heated at 90 °C for 48 hours. After the reaction is completed and the reactor is naturally cooled to room temperature, a centrifuge (8000 rpm, centrifugation for 5 min) is used to remove the substances that do not participate in the reaction in the upper clear liquid to obtain a dark blue solid in the lower layer. The dark blue solid is washed with DMF and anhydrous ethanol for multiple times, and then dried at 60 °C. The mixture was vacuum dried and activated in a vacuum drying oven at 60 °C for 12 hours to obtain a dark blue solid powder, namely the Cu-AIA / BTC MOF material.

[0014] The dual-ligand Cu-MOF material synthesized in the above implementation case has a low fluorescence background and can be used for rapid screening and detection of glyphosate in a fluorescence-on manner with a detection limit of 33 nM; it can also be used for imaging of glyphosate in plant tissues.

[0015] The above description is only an implementation example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein, and all these modifications and substitutions shall fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a dual-ligand Cu-MOF for rapid screening and detection of glyphosate, characterized by The following steps are performed: (1) Weigh appropriate amounts of Cu(NO3)2 3H2O, 2-aminoisophthalic acid and trimesic acid, use N,N-dimethylformamide (DMF) as solvent, and ultrasonically dissolve the above substances to obtain a clear solution; (2) The obtained clarified mixed solution was transferred to a reactor lined with 100 mL polytetrafluoroethylene. After the reactor was tightened repeatedly, it was placed in an electric constant temperature drying oven and heated at 90 °C for 24 to 48 hours. (3) After the reaction is completed and the reactor is naturally cooled to room temperature, it is washed several times with DMF and ethanol and vacuum dried at 60 °C for 10 to 12 hours. After activation and drying, a dark blue solid powder is obtained, which is a non-luminescent dual-ligand Cu-MOF material.

2. The method according to claim 1, characterized in that Using Cu 2+ The Cu-MOF material is synthesized with 2-aminoisophthalic acid and trimesic acid as the metal central ion and double ligands.

3. The method according to claim 1, characterized in that The synthesis of dual-ligand Cu-MOF materials requires heating at 90 °C for 24 to 48 hours.

4. The method according to claim 1, characterized in that After the dual-ligand Cu-MOF material is synthesized, it needs to be vacuum dried and activated in a vacuum drying oven at 60°C for 10 to 12 hours.