| Abstract
| - Electron transfer over long distances is important for many future applications in molecularelectronics and solar energy harvesting. In these contexts, it is of great interest to find molecular systemsthat are able to efficiently mediate electrons in a controlled manner over nanometer distances, that is,structures that function as molecular wires. Here we investigate a series of butadiyne-linked porphyrinoligomers with ferrocene and fullerene (C60) terminals separated by one, two, or four porphyrin units (Pn,n = 1, 2, or 4). When the porphyrin oligomer bridges are photoexcited, long-range charge separated statesare formed through a series of electron-transfer steps and the rates of photoinduced charge separationand charge recombination in these systems were elucidated using time-resolved absorption and emissionmeasurements. The rates of long-range charge recombination, through these conjugated porphyrinoligomers, are remarkably fast (kCR2 = 15 − 1.3 × 108 s-1) and exhibit very weak distance dependence,particularly comparing the systems with n = 2 and n = 4. The observation that the porphyrin tetramermediates fast long-range charge transfer, over 65 Å, is significant for the application of these structures asmolecular wires.
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