Sustained-Release and Rapid-Release of Fenhexamid via the Two Different Photocages in a Light-Controllable Manner

Pesticides play a vital role in crop production and food security. Regarding the poor solubility, volatilization, and leaching of pesticides, few strategies can be employed to enhance pesticide efficacy on a spatiotemporal level. Herein, two different photocages derived from o-nitrobenzyl alcohol and coumarin were incorporated into fenhexamid (FEN) to generate novel molecules capable of providing controllable sustained-release and rapid-release of FEN, respectively. The 6-nitropiperanol (NP) modified FEN, NP-FEN, showed 153-fold differences in fungicidal activity between the light and dark treatments. In contrast, the 7-diethylamino-4-hydroxymethyl coumarin (COU) caged FEN, COU-FEN, showed a 13-fold increase in antifungal activity when exposed to light. Further physical and biological assays indicated that FEN could be effectively utilized in a light-controllable manner, which could be a future strategy to mitigate pesticide wasting and improve bioavailability in relation to pesticide residues, resistance, and environmental pollution.