Spontaneous and Simultaneous Oxidation and Reduction of o-Quinones in Water Microdroplets

Microdroplet chemistry has been an emerging new field for its large plethora of unique properties, among which an especially intriguing one is the strong oxidizing and reducing powers. The hydroxide ion in water microdroplets is considered to split into a hydroxyl radical and an electron at the air-water interface, and the former is responsible for the oxidizing capability while the latter is responsible for the reducing power, making a unity of opposites. However, to date there are only two examples showing that oxidation and reduction occur simultaneously to the same substrates, which might be a result of the redox properties of the substrate per se. In this study, we carefully chose a group of omicron- quinone compounds as the substrates in water microdroplets and discovered that they can be both oxidized by the hydroxyl radical and reduced by the electron. These results keep pushing the limit of the unique redox properties of microdroplet chemistry.