Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 64: Metal Substrates: Adsorption of Organic/Bio Molecules IV
O 64.1: Vortrag
Donnerstag, 28. Februar 2008, 11:15–11:30, HE 101
Molecular Recognition on Surfaces: Controlling Dimensionality and Periodicity of Supramolecular Tetraarylporphyrin Assemblies by the Interplay of Cyano and Alkoxy Substituents — •Nikolai Wintjes1, Jens Hornung2, Jorge Lobo-Checa1, Tobias Voigt2, Tomáš Samuely1, Carlo Thilgen2, Meike Stöhr1, François Diederich2, and Thomas Jung3 — 1Department of Physics, University of Basel, CH-4056 Basel — 2Laboratorium für Organische Chemie, ETH-Zürich, Hönggerberg, HCI, CH-8093 Zürich — 3Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH-5232 Villigen PSI
The self-assembly of three porphyrin derivatives was studied in detail on a Cu(111) substrate by means of Scanning Tunneling Microscopy (STM). All derivatives bear two 4-cyanophenyl substituents in opposing meso-positions of the porphyrin core but differ in the nature of the other two meso-alkoxyphenyl substituents. At coverages below 0.8 monolayers, two derivatives form molecular chains which evolve into nanoporous networks at higher coverages. The third derivative self-assembles directly into a nanoporous network without showing a one-dimensional phase. The pore-to-pore distances for the three networks depend on the size and shape of the alkoxy substituents. All observed effects are explained by (i) an interplay between the steric demand of the alkoxy residues, (ii) polar bonding involving both cyanophenyl and alkoxyphenyl substituents, and (iii) the entropy/enthalpy balance of the network formation.