Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 21: Photochemistry
MO 21.3: Vortrag
Freitag, 21. März 2014, 11:00–11:15, BEBEL HS213
Self-Assembly and Size-Dependent Optical Properties of Perylene Bisimide Dye Aggregates — •Franziska Fennel1, Steffen Wolter1, Zengqi Xie2, Per-Arno Plötz1, Oliver Kühn1, Frank Würthner2, and Stefan Lochbrunner1 — 1Institut für Physik, Universität Rostock, Universitätsplatz 3, 18055 Rostock — 2Institut für Organische Chemie und Center for Nanosystem Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg
Molecular self-assembly is widely applied to create functional nanostructures. However, in many cases a quantitative description of the assembly processes is missing. In the presented work, the self-assembly of a perylene bisimide dye and the associated changes in the photophysical properties are investigated [1]. We find a remarkable behavior of the fluorescence yield upon aggregation, which first decreases and then increases again. The findings point to the presence of three different species during the assembly process, namely monomers, dimers with H-type and aggregates with J-type characteristics. An aggregation model is developed, which describes quantitatively the assembly process and the concentration dependence of the photophysical properties. The basic concept is that with increasing concentration first energetically favored dimers are formed which are not suitable for the association of further monomers due to their geometry. Larger aggregates are formed via a second dimeric species, which exhibits a different structure than the energetically favored dimer. This mechanism should also be responsible for the aggregation behavior of many other compounds. [1] Fennel F. et. al. J. Am. Chem. Soc., 2013, 135 (50),18722