A facile and highly efficient fluorescent turn-on switch strategy based on diketone isomerization and its application in peroxynitrite fluorescent imaging.

• A facile and highly efficient fluorescence turn-on switch strategy based on the diketone isomerization was developed. • Peroxynitrite can selectively mediate this isomerization, and a selective probe of peroxynitrite was established. • The probe showed faster response time, lower detection limit and high selectivity toward peroxynitrite. • The probe was applied to the imaging of endogenously peroxynitrite in living cells. A fluorescence turn-on switch induced by functional group conversion offers great potential in fluorescent probes and bioimaging due to its high specificity and efficiency. Exploring novel fluorescence turn-on switches and their singling mechanism are of great significance. In this manuscript, a novel fluorescent turn-on switch strategy induced by diketone isomerization was reported. It was found that when the diketone group of the synthesized coumarin derivative was converted into its monoketone or carboxylic acid derivatives, it could be illuminated. With this fluorescence turn-on strategy, the obtained probe could be used as a trigger for peroxynitrite (ONOO−). The imaging and monitoring of ONOO− in RAW 264.7 cells endogenously induced by acetaminophen and heat shock were successfully achieved. This diketone isomerization strategy will promote the design and construction of a series of novel redox probes. [ABSTRACT FROM AUTHOR]