Long Range Coherent Energy Transfer in Artificial Multichromophoric Antenna Systems—A Case of Breaking Kasha's Rule

Abstract

Ultrafast long‐range energy transfer with unitary quantum‐yield has been studied in a novel family of artificial DNA‐guided multichromophoric antenna complexes with phenanthrene moieties as light harvesters. By means of femtosecond transient absorption spectroscopy and time‐dependent density function theory calculations, we demonstrate that the highly efficient long‐range energy transfer occurs via a coherent mechanism. It is enabled by photoexcitation of higher lying delocalized excited states of phenanthrene, and hence, can be labelled anti‐Kasha in nature. Moreover, we show the important contribution of exciplex formation between acceptor and closest donor.