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

Abstract

Multichromophoric systems based on a RuII 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 RuII photosensitizer, namely [(tbbpy)2Ru((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 μs) dark state in acetonitrile solution. Compared to prototype [(bpy)3Ru]2+-like complexes, a strongly altered absorption (ϵ=50.3×103 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.