Shedding Light On The Nature Of Photoinduced States Formed In A Hydrogen-Generating Supramolecular Rupt Photocatalyst By Ultrafast Spectroscopy

Photoinduced electronic and structural changes of a hydrogen generating supramolecular RuPt photocatalyst are studied by a combination of time-resolved photoluminescence, optical transient absorption, and X-ray absorption spectroscopy. This work uses the element specificity of X-ray techniques to focus on the interplay between the photophysical and-chemical processes and the associated time scales at the catalytic Pt moiety. We observe very fast (<30 ps) photoreduction of the Pt catalytic site, followed by an similar to 600 ps step into a strongly oxidized Pt center. The latter process is likely induced by oxidative addition of reactive iodine species. The oxidized Pt species is long-lived and fully recovers to the original ground state complex on a >10 mu s time scale. However, the photosensitizing Ru moiety is fully restored on a much shorter similar to 300 ns time scale. This reaction scheme implies that we may withdraw two electrons from activated by a single photon.