Click 1,2,3-triazole derived fluorescent scaffold by mesoionic carbene–nitrene cyclization: an experimental and theoretical study

We describe a set of three fluorescent mesoionic benzo[4,5]imidazo-3-ide-[1,2-c]-2-alkyl-1,2,3-triazol-2-ium compounds obtained through a simple, concise and efficient synthetic sequence featuring a copper-catalyzed carbene–nitrene cyclization. The compounds were characterized by fluorescence spectroscopy highlighting promising photophysical properties in terms of quantum yields and Stokes shifts. Experimental properties were rationalized by a computational DFT and TD-DFT approach with excellent agreement with structural and spectroscopic data.