Merging of a Perylene Moiety Enables a RuII Photosensitizer with Long-Lived Excited States and the Efficient Production of Singlet Oxygen

Multichromophoric systems based on a Ru-II polypyridine moiety containing an additional organic chromophore are of increasing interest with respect to different light-driven applications. Here, we present the synthesis and detailed characterization of a novel Ru-II photosensitizer, namely [(tbbpy)(2)Ru((2-(perylen-3-yl)-1H-imidazo[4,5-f][1,10]-phenanthrolline))](PF6)(2) RuipPer, that includes a merged perylene dye in the back of the ip ligand. This complex features two emissive excited states as well as a long-lived (8 mu s) dark state in acetonitrile solution. Compared to prototype [(bpy)(3)Ru](2+)-like complexes, a strongly altered absorption (epsilon=50.3x10(3) M-1 cm(-1) at 467 nm) and emission behavior caused by the introduction of the perylene unit is found. A combination of spectro-electrochemistry and time-resolved spectroscopy was used to elucidate the nature of the excited states. Finally, this photosensitizer was successfully used for the efficient formation of reactive singlet oxygen.

Automated summary

A novel Ru-II photosensitizer, RuipPer, containing a merged perylene dye, shows two emissive excited states and a long-lived dark state. The introduction of the perylene unit results in strongly altered absorption and emission behavior compared to prototype complexes.