Ultrafast Intramolecular Relaxation and Wave‐Packet Motion in a Ruthenium‐Based Supramolecular Photocatalyst

E-ISSN： 1521-3765|21|21|7668-7674

ISSN： 0947-6539

Source： CHEMISTRY - A EUROPEAN JOURNAL, Vol.21, Iss.21, 2015-05, pp. : 7668-7674

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

AbstractThe hydrogen‐evolving photocatalyst [(tbbpy)2Ru(tpphz)Pd(Cl)2]2+ (tbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, tpphz=tetrapyrido[3,2‐a:2′,3′‐c:3′′,2′′‐h:2′′′,3′′′‐j]phenazine) shows excitation‐wavelength‐dependent catalytic activity, which has been correlated to the localization of the initial excitation within the coordination sphere. In this contribution the excitation‐wavelength dependence of the early excited‐state relaxation and the occurrence of vibrational coherences are investigated by sub‐20 fs transient absorption spectroscopy and DFT/TDDFT calculations. The comparison with the mononuclear precursor [(tbbpy)2Ru(tpphz)]2+ highlights the influence of the catalytic center on these ultrafast processes. Only in the presence of the second metal center, does the excitation of a 1MLCT state localized on the central part of the tpphz bridge lead to coherent wave‐packet motion in the excited state.