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Energy vs. electron transfer – controlling the excitation transfer in molecular triads NUMBERS

Luo, Yusen; Barthelmes, Kevin; Wächtler, Maria; Winter, Andreas; Schubert, Ulrich S.; Dietzek, Benjamin
in: Chemistry-A European Journal (2017) 4917

The photochemistry of Ru(II) coordination compounds is generally discussed to originate from the lowest lying triplet metal-to-ligand charge-transfer state (3MLCT). However, when heteroleptic complexes are considered, e.g. in the design of molecular triads for efficient photo induced charge separation, a complex structure of1MLCT states, which can be populated in a rather narrow spectral window (typically around 450 nm) is to be considered. In this communication we show that the localization of MLCT excited states on different ligands can affect the following ps to ns decay pathways to an extend that by tuning the excitation wavelength intermolecular energy transfer from a Ru(II)-terpyridine unit to a fullerene acceptor can be favored over electron transfer within the molecular triad. These results might have important implications for the design of molecular dyads, triads, pentads and so forth with respect to a specifically targeted response of these complexes to photoexcitation.

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