Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Surface chemical reactions I
O 49.4: Talk
Wednesday, March 24, 2010, 11:15–11:30, H42
Switching Single Azopyridine Supramolecules in Ordered Array on Au(111) — •Yongfeng Wang1, Xin Ge1, Guillaume Schull1, Richard Berndt1, Hao Tang2, Claudia Bornholdt3, Felix Koehler3, and Rainer Herges3 — 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, D-24098 Kiel, Germany — 2CEMES/CNRS, France — 3Institut für Organische Chemie, Christian-Albrechts-Universität, D-24098 Kiel, Germany
Understanding and controlling molecular switches on surfaces is of
interest in both fundamental science and functional device at the single
molecule level. Single molecular switches have been realized by modifying
covalent bonds or ionic bonds. Decoupling of the reactive component
of the molecule from a metal substrate by an insulating layer can be
necessary as reversible switching is usually quenched on metals for the
rather high barrier to overcome and the short lifetime of excitations. In
contrast to molecules, supramolecules are connected through weak noncovalent interactions like hydrogen bonding. Lower
energy barriers to switching may be expected for these weaker bonds. Here we report on supramolecular
switches of 4,4-azopyridine trimers and 4-phenylazopyridine dimers in
ordered array on Au(111). During switching, a single weak C-H...N hydrogen
bond breaks and reforms. For 4,4-azopyridine, the switching mechanism
occurs via electron attachment. 4-phenylazopyridine dimer, however, can be
switched by electric fields, too. Funding by the Deutsche Forschungsgemeinschaft
through SFB 677 is acknowledged.