Electron transit through iron compound
doi:10.1038/nindia.2010.76 Published online 9 June 2010
Researchers have shown that ferrocene, an organometallic compound, can be laid on gold surfaces to yield novel optoelectronic devices. Such ferrocene-modified conducting surfaces could find new use in biomolecular recognition and in the controlled release of drugs.
Ferrocene exhibits attractive electrochemical properties such as fast electron transfer, low oxidation potential, and stability, making it a good candidate for grafting onto conducting surfaces such as doped semiconductors, metals and carbonaceous materials.
However, the anchoring of this iron compound using non-covalent interactions is not well explored. To investigate the potential of such interactions, the researchers first smeared a uracil-terminated (RNA base) monolayer onto a gold surface and then grafted adenine (a base found both in DNA and RNA)-substituted ferrocene on top.
The uracil monolayer was bound to the adenine-substituted ferrocene through hydrogen bonding. When a voltage was applied, the molecular assembly on the gold surface showed a perfectly electrochemical response (reduction–oxidation activity through electron transfer) due to the bound ferrocene units.
The electrochemical activity was not observed with a uracil-terminated monolayer treated with no adenine-substituted ferrocene derivative. This proves that ferrocene anchors through hydrogen bonding and that electrons move through it.
The ferrocene-modified gold surfaces show a 20% loss of electrochemical activity after 1,500 cycles. "This type of non-covalent assembly could be extended to other nucleobase-functionalized structures such as carbon nanotubes, nanoparticles and polymers," says lead researcher Bruno Fabre.
The authors of this work are from: Sciences Chimiques de Rennes, and Institut de Physique de Rennes, Equipe de Physique des Surfaces et Interfaces, Université de Rennes, MaCSE, Campus de Beaulieu, Rennes Cedex, and CNRS, Institut de Biologie Moléculaire et Cellulaire, Laboratoire d'Immunologie et Chimie Thérapeutiques, Strasbourg, France and Department of Chemistry, Indian Institute of Technology-Kanpur, Kanpur, India.