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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 1: Supramolecular Aggregates

CPP 1.6: Vortrag

Montag, 26. März 2007, 11:15–11:30, H37

Balance of structure-building forces in aliphatic self-assembled monolayers on metal substrates — Andrey Shaporenko¹, Tobias Weidner¹, Andreas Terfort², and •Michael Zharnikov¹ — ¹Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany — ²Anorganische und Angewandte Chemie, Universität Hamburg, 20146 Hamburg, Germany

Using self-assembled monolayers (SAMs) of biphenyl-substituted alkaneselenols (BPnSe, where n = 2-6 is the number of the methylene units in the aliphatic linker) on gold and silver substrates as a model system, we demonstrate that the bonding configuration of the selenol headgroup is the deciding factor in the balance of structure-building interaction in the alkaneselenol SAMs. The energy associated with the persistence of this configuration is high enough to prevail over the energy gain associated with the optimal (i.e., dense) packing of the biphenyl moieties in the BPnSe SAMs. Considering, that the similar effects have been observed for the alkanethiolate SAMs, we can conclude on the generality of this phenomenon, stating that the exact bonding configuration of the headgroup is an important or, in most cases, even deciding factor in the balance of different contributions responsible for the molecular packing and structure of aliphatic self-assembled monolayers on metal substrates. This bonding configuration can be alternatively associated with a definite hybridization of the sulphur atom in the substrate-sulfur-carbon joint or a definite geometry of the adsorption site on the given substrate.