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Oxidation of an Organic Adlayer: A Bird’s Eye View

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journal contribution
posted on 30.05.2012, 00:00 by Thomas Waldmann, Daniela Künzel, Harry E. Hoster, Axel Groß, R. Jürgen Behm
The reaction of O2 with an adlayer of the oligopyridine 2-phenyl-4,6-bis­(6-(pyridine-2-yl)-4-(pyridine-4-yl)-pyridine-2-yl)­pyrimidine (2,4′-BTP), adsorbed on the (111) surfaces of silver and gold and on HOPG – which can be considered as a model system for inorganic|organic contacts – was investigated by fast scanning tunneling microscopy (video STM) and dispersion corrected density functional theory (DFT-D) calculations. Only on Ag(111), oxidation of the 2,4′-BTP adlayer was observed, which is related to the fact that under the experimental conditions O2 adsorbs dissociatively on this surface leading to reactive O adatoms, but not on Au(111) or HOPG . There is a distinct regiospecifity of the oxidation reaction caused by intermolecular interactions. In addition, the oxidation leads to a chiral ordering. The relevance of these findings for reactions involving organic monolayers is discussed.