Metalorganic Polyhedra Polyoxometalate Hybrid Salts for Tandem Photooxidative-Hydrolytic Pesticide Detoxification

Abstract

The extensive use of pesticides to ensure global food production presents significant threats to both human health and the environment. In this study, the photochemical, redox, and acid-base properties of Zr-metal-organic polyhedra (Zr-MOP) and polyoxometalates (POM) are utilized to fabricate functional hybrid salts, denoted as [Zr-MOP][POM], designed for pesticide detoxification. Upon light irradiation, [Zr-MOP][POM] salts generate a charge-separated state with oxidizing properties. This activated state selectively photooxidizes highly toxic and persistent fenamiphos into fenamiphos sulfoxide and subsequently hydrolytically breaks down it into non-toxic 3-methyl-4-(methylsulfinyl)phenol and phosphate components. The hydrolytic degradation of fenamiphos is facilitated by the reduced basicity of the 3-methyl-4-(methylsulfinyl)phenolate residue (ΔpKb = -2.4) in the photooxidized form of the pesticide molecule. Furthermore, the hybrid salts demonstrate efficacy in the breakdown of multicomponent pesticide mixtures such as fenamiphos and methylparaoxon.