Developing a Novel Agrochemical-Based MOF: A Multifunctional Platform with Herbicidal and Antibacterial Activities

Abstract

Excessive and uncontrolled application of agrochemicals has resulted in contamination of terrestrial and aquatic environments. In the past decade, metal–organic frameworks (MOFs) have been studied as agrochemical release systems to enhance efficiency while reducing the leaching of toxic molecules to the environment. In this work, we take a further step and use organic agrochemicals as linkers in the preparation of MOFs, which we have called AgroMOFs. Particularly, we have prepared a novel 2D framework, named GR-MOF-20, based on the flexible herbicide glyphosine (H₅Gly) and the widely used antibacterial and fungicide Cu²⁺. After complete characterization by single-crystal and powder X-ray diffraction and high-performance liquid chromatography (HPLC), a fascinating transformation of the structure to a novel 3D-MOF (GR-MOF-21) after in water is observed, together with a burst degradation (86.0 ± 3.2% after 72 h). Considering the bioactivity of its building blocks (H₅Gly and Cu²⁺), the combined herbicidal and antibacterial activities of GR-MOF-21 were demonstrated. Aqueous solutions prepared with GR-MOF-20 (450 mg L^–1) demonstrated a better inhibition effect (21.7 ± 2.9% after 7 days) in the germination of seeds of the invasive weed Lolium multiflorum than the free H₅Gly (13.3 ± 2.9%). Further, the selectivity of GR-MOF-21 was tested against a nontarget plant (wheat, Triticum aestivum). Finally, GR-MOF-21 showed an important antibacterial activity against Escherichia coli and Pseudomonas syringae, achieving the results obtained with Cu²⁺ solutions. These observations demonstrated that the use of herbicide and antibacterial units in the MOF construction is an efficient approach to controlling bacteria and weed plants without damaging wheat crops.