Sprayed water microdroplets containing dissolved pyridine spontaneously generate pyridyl anions

Abstract

Significance Water microdroplets can accelerate chemical reactions by orders of magnitude compared to the same reactions in bulk water and/or trigger spontaneous reactions that do not occur in bulk solution. Among the properties of water microdroplets, the unique redox ability resulting from the spontaneous dissociation of OH − into a released electron and •OH at the air–water interfaces is especially intriguing. At the air–water interface, OH − exhibits a strong reducing potential, and the resulting •OH is highly oxidative, making water microdroplets a unity of opposites. We report the reduction of pyridine into pyridyl anions (C 5 H 5 N − ) and the oxidation of pyridine into hydroxypyridine, which extends what we know about the redox power of water microdroplets.