4,4'-Dicyano- versus 4,4'-Difluoro-BODIPYs in Chemoselective Postfunctionalization Reactions: Synthetic Advantages and Applications.

The presence of F or CN substituents at boron in BODIPYs causes a dramatic effect on their reactivity, which allows their chemoselective postfunctionalization. Thus, whereas 1,3,5,7-tetramethyl B(CN) 2 -BODIPYs displayed enhanced reactivity in Knoevenagel condensations with aldehydes, the corresponding BF 2 -BODIPYs can experience selective aromatic electrophilic substitution (S E Ar) reactions in the presence of the former. These (selective) reactions have been employed in the preparation of BODIPY dimers and tetramers, with balanced fluorescence and singlet oxygen formation, and all-BODIPY trimers and heptamers, with potential application as light-harvesting systems.