Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System

Abstract

The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 A, is calculated from the experimental energy transfer rate using Forster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime w...