We have studied long-range electron transfer through various lengths of helical peptides from 8 mer (30 �) up to 64 mer (110 �) in self-assembled monolayers prepared on a gold surface. Helical peptides carrying a redox-active ferrocene unit and a disulfide group at the respective terminals were synthesized and immobilized on gold via a gold-sulfur linkage to form a well-defined monolayer with vertical helix orientation, and the electron transfer from the ferrocene unit to gold through the helical peptides was studied by electrochemistry. The electron transfer showed a very shallow distance dependence and high activation energies, both of which are characteristic of a hopping mechanism. Detailed theoretical calculations successfully demonstrated that a hopping mechanism with the amide groups as hopping sites is responsible for the long-range electron transfer, which enables ultralong-range electron transfer over 100 � with the 64 mer helical peptide.

An electron hops along α-helix over 100 [Aring]

240th National Meeting (2010)

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