Photogeneration of singlet oxygen catalyzed by hexafluoroisopropanol for selective degradation of dyes.

Singlet oxygen (O) shows great potential for selective degradation of dyes in environmental remediation of wastewater. In this study, we showcased that O can be effectively generated from an anion complex composed of deprotonated hexafluoroisopropanol anion ([HFIP]) with hydroperoxyl radical (⋅HO) via ultraviolet (UV) photodetachment. Electronic structure calculations and cryogenic negative ion photoelectron spectroscopy unveil critical proton transfer upon complex formation and electron ejection, effectively photoconverting prevalent triplet ground state O to long-lived excited O, stabilized by nearby HFIP. Inspired by this spectroscopic study, a novel "photogeneration" strategy is proposed to produce O with the incorporation of atmospheric O and HFIP, acting as a catalyst. Conceptually, the designed catalytic cycle upon UV irradiation and electron injection is able to achieve different degradations of dye molecules in a controllable fashion from decolorization to complete mineralization, shedding new light on potential water purification.