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 <i>Lolium multiflorum</i> than the free H₅Gly (13.3 ± 2.9%). Further, the selectivity of GR-MOF-21 was tested against a nontarget plant (wheat, <i>Triticum aestivum</i>). Finally, GR-MOF-21 showed an important antibacterial activity against <i>Escherichia coli</i> and <i>Pseudomonas syringae</i>, 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.