Phosphorescent Bismoviologens for Electrophosphorochromism and Visible Light-Induced Cross-Dehydrogenative Coupling

A series of novel bismuth-bridged viologen analogues, bismoviologens (BiV²⁺), synthesized through a combination of a bismuth atom and viologen skeleton is reported. Their optical and electrochemical properties were fine-tuned through the N-arylation or N-alkylation reactions. Bismolviologens not only showed good redox properties but also exhibited phosphorescence under ambient conditions (in air at room temperature). This phenomenon makes BiV²⁺ the first examples of phosphorescent viologen analogues reported to date. On the basis of the excellent and unique redox and optical properties of BiV²⁺, their electrophosphorochromic devices were fabricated. Furthermore, BiV²⁺ was used for the first time as both a photocatalyst and electron mediator in visible light-induced cross-dehydrogenative coupling reactions.