Modulating the Oxidation of FMNH₂ by Organophosphorus Compounds

Abstract

The oxidation of FMNH₂ by three organophosphorus compounds ethion, fenthion and diethyl chlorophosphate has been investigated. FMNH₂ was produced in methanol solvent by the photoreduction of FMN. In aqueous solution, FMN is not fully reduced to FMNH₂ but instead yields the semiquinone radical FMNH•. However, when FMN was anchored to nanocrystalline TiO₂, bandgap irradiation resulted in electron transfer from the TiO₂ conduction band to FMN, thus yielding FMNH₂. Additionally, FMNH₂ accompanied by TiO₂ conduction band electrons, produced in methanol solvent were found to react rapidly with the organophosphorus compounds investigated. The advantages of the described system are (1) the reactivity with the organophosphorus compounds occurs at mild conditions, (2) via simple modulation of external environmental factors the reactivity of the system can be tuned, and (3) the reactivity occurs in both aqueous solutions and organic solvents.