Synthesis and characterization of aryl-substituted BODIPY dyes displaying distinct solvatochromic singlet oxygen photosensitization efficiencies

Three BODIPY derivatives substituted at meso position by aryl (phenyl or N,N-dimethylaminonaphthyl) groups and functionalized 2 with electron-withdrawing formyl electron deficient benzimidazole heterocycle were synthesized completely characterized the usual spectroscopic techniques. A comprehensive photophysical study showed a remarkable enhancement of singlet oxygen sensitization quantum yield for meso-substituted dimethylaminonaphthyl decrease dielectric constant solvent (0.02–0.04 dimethylsulfoxide vs. 0.84 in toluene). In toluene triplet state formation aminonaphthyl BODIPY's was found to be mediated intramolecular charge transfer (ICT), whereas polar solvents is hindered fast recombination ICT state. Pump-probe transient absorption spectroscopy used characterize photoinduced dynamics from femtosecond nanosecond time scale.