Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Organic/bio Molecules on Metal Surfaces IV

O 42.5: Vortrag

Mittwoch, 13. März 2013, 11:30–11:45, H38

Chemical Transformations of Bisphenol A on Cu(111) and Ag(111) — •Julian Lloyd, Sybille Fischer, Anthoula Papageorgiou, Matthias Marschall, Joachim Reichert, Katharina Diller, Florian Klappenberger, Francesco Allegretti, and Johannes V. Barth — Physik Department E20, TUM, Garching

Bisphenol A (BPA) is a common additive to everyday polymers and its suspected adverse health effects led to its EU ban from use in baby bottles in June 2011. Some of these effects are traced to DNA alterations [1]. The reactivity of BPA has not been reported in a systematic way and the key molecular events and interactions driving the self-assembly of non-coplanar phenols have hitherto not been addressed unambiguously by a combinatorial approach of microscopy and spectroscopy. In this study we address the chemical transformations of BPA on transition and noble metal surfaces, copper and silver. These transformations are expected to induce changes in the surface self-assembly. Performing a scanning tunneling microscopy study of BPA on a Cu(111) and a more inert Ag(111) surface we observed multiple extended two dimensional networks dependent on temperature and substrate metal. To further elucidate the chemical state and the orientation of the molecule in the aforementioned phases, we performed synchrotron X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure studies. We find a complex, stepwise deprotonation scheme mediating the structural transformations. Based on the data sets we present a simple comprehensive model of the observed phases.

[1] D.C. Dolinoy, et. al. PNAS 104, 13061 (2007).