Coumarin 343 is a blue emitting fluorophore with an emission maximum around 480 nm. This dye forms a FRET pair with fluorescein, and can harvest blue light energy for the subsequent transfer to other fluorophores.
The azide derivative can be conjugated with alkynes in a copper-catalyzed and copper-free Click chemistry reactions. The molecule contains a long aminohexanoyl linker that provides separation between the dye, and the azide function.