Fluorogenic Coumarins Activated via Bioorthogonal Reaction

Fluorogenic bioorthogonal reagents enable facile detection in complex environments. While useful for real-time imaging, few such probes are available. Existing tools also exploit similar mechanisms for signal turn-on, precluding multiplexed applications. To address these gaps, we developed a palette of cyclopropenone (CpO) scaffolds that are activated by bioorthogonal phosphines to provide coumarins. The top CpO-phosphine pairs show strong fluorescent enhancements (up to 760-fold) and high quantum yields, and are stable in aqueous environments. The CpO fluorogens also exhibit unique reaction profiles, setting the stage for multi-component labeling studies.