Exploring N-BODIPYs as privileged scaffolds to build off/on fluorescent sensors by PET.

The detection and quantification of ions or neutral molecules by fluorescent sensors are of utmost importance in chemistry, medicine and environmental sciences. In this context, BODIPYs (boron dipyrromethenes) are outstanding chromophores for the development of fluorescent sensors owing to their excellent photophysical properties and the possibility of modulating such properties by chemical changes in their structure. We have recently reported a new class of BODIPY dyes, the N-BODIPYs, that is, BODIPYs with N-moieties attached to the boron atom. These new dyes have the advantage, over the widely extended F-BODIPYs, that up to four different groups can be attached to the boron through the nitrogen atoms. This structural feature expands the possibility of BODIPY functionalization, thus increasing the versatility of the dyes for different photonic applications. Particularly, we found, in certain N-BODIPYs, a photoinduced electron transfer (PET) from the N-moiety attached to the boron towards the BODIPY core that quenches the fluorescence of the dye. In this communication, we explore the possibility of modulating this PET for the development of fluorescent off/on sensors based on N-BODIPYs.