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

Abstract

A preparation method of a dual-ligand Cu-MOF material for rapid screening and detection of glyphosate, mainly using Cu 2+ As a metal center ion, 2-amino isophthalic acid (AIA) and trimesic acid (H3BTC) as ligand, a dual-ligand Cu-AIA / BTC MOF material with low fluorescence background was synthesized by solvothermal synthesis method. Due to ligand-metal charge transfer (LMCT) and photoinduced electron transfer (PET) effect between ligands, the fluorescence of ligand AIA is almost completely quenched in Cu-MOF (quenching efficiency is 98%). After glyphosate is added, it competes with the ligand in Cu-MOF, leading to the collapse of MOF structure and the release of ligand, and the fluorescence of AIA is restored. Under the optimal conditions, the Cu-MOF nanoprobe has a good linearity for glyphosate concentration in the range of 0.1-100 μM, and the detection limit is 33 nM. The Cu-MOF nanoprobe has high sensitivity, good selectivity and the ability to visually detect 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 and soil, indicating that the nanoprobe has broad application prospects.

Description

Technical Field

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

[0002] Glyphosate is a highly effective, broad-spectrum organophosphorus herbicide widely used in weed control during agricultural production. With the expansion of its application and the increase in dosage, glyphosate enters the ecological environment through various pathways, including pesticide spraying, absorption and translocation via plant roots, surface runoff, and erosion, disrupting the original ecological structure. Simultaneously, glyphosate can accumulate in the human body through the food chain, posing potential carcinogenic and genotoxic effects, and may damage the immune and endocrine systems, thus endangering human health. Therefore, monitoring the content of glyphosate in plants, soil, and water is crucial (Sci TotalEnviron, 2020, 705, 135808; Chemosphere, 2022, 298, 134308; Water Res, 2013, 47, 5110-5120). Currently, commonly used analytical methods for glyphosate include high-performance liquid chromatography (HPLC) and gas chromatography (GC), which offer advantages such as high sensitivity and accuracy. However, due to the lack of chromophores and fluorescent groups in glyphosate, its analysis typically requires complex derivatization processes. Optical sensing has been developed for rapid on-site detection of glyphosate due to its advantages such as simple equipment requirements and fast response speed, including carbon quantum dots (CDs), metal-organic frameworks (MOFs), and small organic molecule probes (Food Chem, 2023, 403, 134346; New J Chem, 2022, 46, 19808-19816; Talanta, 2021, 224, 121834). However, these probes often have high fluorescence background or require Cu... 2+ As an intermediate quantitative analyte, it is not suitable for the detection of trace amounts of glyphosate. Therefore, this invention utilizes a dual-ligand strategy to synthesize a dual-ligand Cu-MOF material with low fluorescence background for rapid screening and detection of glyphosate via fluorescence activation. Summary of the Invention

[0003] The purpose of this invention is to synthesize a metal-organic framework material with low fluorescence background for rapid screening and detection of glyphosate pesticides in the environment via fluorescence activation, and for use in plant tissue imaging of glyphosate. The main component is Cu. 2+A low-fluorescence-background dual-ligand Cu-AIA / BTC MOF material was synthesized using a solvothermal synthesis method with 2-aminoisophthalic acid (AIA) as the central metal ion and pyromellitic acid (H3BTC) as ligands. 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 the addition of glyphosate, the fluorescence of the central Cu-AIA / BTC material was further enhanced due to the interaction between glyphosate and the central Cu ion. 2+ Competition for coordination leads to the collapse of the Cu-MOF structure, resulting in the release of ligands and the recovery of fluorescence in the AIA ligand, thereby enabling rapid detection of glyphosate via fluorescence activation. The technical solution of this invention is as follows:

[0004] Weigh appropriate amounts of Cu(NO3)23H2O, 2-aminoisophthalic acid, and trimesic acid, and use N,N-dimethylformamide (DMF) as a solvent to dissolve the above substances by sonication to obtain a clear solution.

[0005] The resulting clear mixed solution was transferred to a reaction vessel lined with 100 mL polytetrafluoroethylene. After repeatedly tightening the reaction vessel, it was placed in an electric thermostatic drying oven and heated at 90 °C for 24–48 hours.

[0006] After the reaction was complete and the reactor cooled naturally to room temperature, the mixture was washed several times with DMF and ethanol, and then vacuum dried at 60 °C for 10–12 hours. After activation and drying, a dark blue solid powder was obtained, which is the non-luminescent dual-ligand Cu-MOF material.

[0007] Compared with the prior art, the present invention has the following advantages:

[0008] Cu is not required 2+ As an intermediate quantitative substance.

[0009] It has a low fluorescence background (fluorescence quenching rate up to 98%).

[0010] It has high sensitivity, with a detection limit of 33 nM for glyphosate.

[0011] It exhibits excellent selectivity and resistance to interference with glyphosate.

[0012] It can be used for imaging glyphosate in plant tissues and for rapid screening and detection of glyphosate in the environment. Detailed Implementation

[0013] Example

[0014] Weigh out 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), and add them to 60 mL of DMF solvent. Dissolve by sonication until the solution is clear. Transfer the resulting clear mixture to a 100 mL polytetrafluoroethylene-lined reactor. Tighten the reactor repeatedly and place it in a thermostatic drying oven at 90 °C for 24 hours. After the reaction is complete and the reactor has cooled to room temperature, centrifuge (8000 rpm, 5 min) to remove unreacted substances from the supernatant, obtaining a dark blue solid. Wash the dark blue solid several times with DMF and anhydrous ethanol, and then dry it at 60 °C. The material was activated by vacuum drying at 60 °C for 12 hours in a vacuum drying oven to obtain a dark blue solid powder, namely Cu-AIA / BTC MOF material.

[0015] Example

[0016] Weigh out 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), and add them to 60 mL of DMF solvent. Dissolve by sonication until the solution is clear. Transfer the resulting clear mixture to a 100 mL polytetrafluoroethylene-lined reactor. Tighten the reactor repeatedly and place it in a thermostatic drying oven at 90 °C for 36 hours. After the reaction is complete and the reactor has cooled naturally to room temperature, centrifuge (8000 rpm, 5 min) to remove unreacted substances from the supernatant, obtaining a dark blue solid. Wash the dark blue solid several times with DMF and anhydrous ethanol, and then dry it at 60 °C. The material was activated by vacuum drying at 60 °C for 12 hours in a vacuum drying oven to obtain a dark blue solid powder, namely Cu-AIA / BTC MOF material.

[0017] Example

[0018] Weigh out 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), and add them to 60 mL of DMF solvent. Dissolve by sonication until the solution is clear. Transfer the resulting clear mixture to a 100 mL polytetrafluoroethylene-lined reactor. Tighten the reactor repeatedly and place it in a thermostatic drying oven at 90 °C for 48 hours. After the reaction is complete and the reactor has cooled naturally to room temperature, centrifuge (8000 rpm, 5 min) to remove unreacted substances from the supernatant, obtaining a dark blue solid in the lower layer. Wash the dark blue solid several times with DMF and anhydrous ethanol, and then dry it at 60 °C. The material was activated by vacuum drying at 60 °C for 12 hours in a vacuum drying oven to obtain a dark blue solid powder, namely Cu-AIA / BTC MOF material.

[0019] The dual-ligand Cu-MOF materials synthesized in the above implementation examples have low fluorescence background and can be used for rapid screening and detection of glyphosate in a fluorescence-on mode, with a detection limit of 33 nM; they can also be used for imaging glyphosate in plant tissues.

[0020] The above description is merely an example of the implementation 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. All such modifications and substitutions should fall within the protection scope of the appended claims of 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: The following steps are required: (1) Weigh appropriate amounts of Cu(NO3)2·3H2O, 2-aminoisophthalic acid, and trimesic acid, and use N,N-dimethylformamide (DMF) as a solvent to dissolve the above substances by sonication to obtain a clear solution; (2) Transfer the obtained clear mixed solution to a reaction vessel lined with 100 mL polytetrafluoroethylene, tighten the reaction vessel repeatedly, and place it in an electric thermostatic drying oven to heat and react at 90 °C for 24 to 48 hours; (3) After the reaction is completed and the reactor is naturally cooled to room temperature, wash several times with DMF and ethanol, and vacuum dry 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... With Cu 2+ Cu-MOF materials were synthesized using 2-aminoisophthalic acid and pyromellitic acid as dual ligands, with 2-aminoisophthalic acid as the metal central ion.