Electron transfer across oligo-ortho-phenylenes
In photosynthesis electron transfer over long distances plays a crucial role and has been studied in many molecular donor-acceptor compounds. Especially para-substituted oligo-phenylenes as molecular bridges have received much attention.1 For electron transfer across para-phenylenes and para-xylenes, time-resolved measurements revealed a significant distance dependence with β parameters of 0.2 Å-1 to 0.8 Å-1, respectively.2
For the first time we investigated photoinduced electron transfer through a molecular bridge consisting of oligo-ortho-phenylenes. Compared to their para connected congeners, these molecules show a much weaker distance dependence for electron transfer.
Comparison of electron transfer rates (kET) vs. donor-acceptor-distances (RDA) in para-phenylenes, para-xylenes, and oligo-ortho-phenylenes.
[1] E. A. Weiss, M. J. Ahrens, L. E. Sinks, A. V. Gusev, M. A. Ratner, M. R. Wasielewski, J. Am. Chem. Soc. 2004, 126, 5577–5584.
[2] D. Hanss, M. E. Walther O. S. Wenger, Coord. Chem. Rev. 2010, 254, 2584–2592.