Visible-light induced photo-click and release strategy between monoarylsydnone and phenoxylfumarate

We report a visible-light induced photo-click and release platform between monoarylsydnone (MASyd) and phenoxylfumarates. The pyrazoline produced by the cycloaddition undergoes a photo-aromatization to form a fluorescent pyrazole. Meanwhile, the photo-aromatization also serves as the driving force to release fluorophores that are quenched in the form of phenoxylfumarates.