Construction of fungicide nano delivery platform through crystal engineering for sustainable fungal control

Abstract

The adverse effects resulting from off-target pesticide application pose significant risks to both ecosystems and public health. Therefore, developing a pesticide delivery system that is straightforward, effective, and devoid of secondary pollution is crucial for environmental safety. Herein, self-assembled crystalline materials involved pyrimethanil (PYR) and organic acids were constructed by crystal engineering. These materials allowed for direct manipulation of the physicochemical properties and environmental fate of PYR by the building modules. The melting point of PYR was increased from 96.19 °C to 206.69 °C. The photostability and volatile stability were improved by 3.85-fold and 297-fold, respectively. Afterwards, these crystalline materials were prepared as nano cocrystal suspensions (NCSs) in water by the one-pot method. The PYR NCSs exhibited potent bioactivity against Botrytis cinerea and demonstrated slow-release behavior. Upon foliar spraying, the PYR NCSs exhibited desirable foliar wettability with a contact angle lower than 36°. By limiting leaching into the soil and reducing environmental pesticide exposure, PYR NCS ensured the safety of both earthworms and plants. The structure–property relationships of PYR NCSs were elucidated through intermolecular interaction analysis and theoretical calculations. Overall, the NCSs constructed by the supramolecular chemistry strategy are characterized by the simple preparation, high bioactivity, stability, no carrier, slow-release, and minimal environmental risk, which offers insight for improving the utilization and sustainable management of pesticides.