Abstract:
A new series of aza-BODIPY derivatives (4a–4c, 5a,c, and 6b,c) were synthesized and their excited-state properties, such as their triplet excited state and the yield of singletoxygen generation, were tuned by substituting with heavy atoms, such as bromine and iodine. The effect of substitution has been studied in detail by varying the position of halogenation. The
core-substituted dyes showed high yields of the triplet excited state and high efficiencies of singlet-oxygen generation
when compared to the peripheral-
substituted systems. The dye 6c, which was substituted with six iodine atoms on the core and peripheral phenyl ring, showed the highest quantum yields of the triplet excited state(FT=0.86) and of the efficiency of singlet-oxygen generation (FD=0.80). Interestingly,these dyes were highly efficient as photooxygenation catalysts
under artificial light, as well as under
normal sunlight conditions. The uniqueness of these aza-BODIPY systems is that they are stable under irradiation conditions, possess strong redlight
absorption (620–680 nm), exhibit
high yields of singlet-oxygen generation,
and act as efficient and sustainable
catalysts for photooxygenation reactions
