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O: Fachverband Oberflächenphysik
O 56: Metal substrates: Adsorption of organic / bio molecules III
O 56.10: Vortrag
Mittwoch, 28. März 2012, 19:00–19:15, A 053
2D glassy crystals from flexible molecular modules — •David Ecija1, Saranyan Viyagaravhan1, Willi Auwärter1, Sushobhan Joshi1, Knud Seufert1, Claudia Aurisicchio2, Davide Bonifazi2, and Johannes V. Barth1 — 1Physik Department E20, Technische Universität München, D-85748 Garching, Germany — 2University of Namur, Department of Chemistry, B-5000 Namur, Belgium
Molecular glassy crystals are materials where the constituents are positioned in registry with a periodic crystalline lattice, but the molecular units are disordered regarding their orientational degrees of freedom. Here, to our knowledge, we present for the first time a two-dimensional (2D) analogue of the three-dimensional glassy crystal state of matter, i.e, a 2D glassy crystal. In particular, the deposition of a flexible molecular module on Cu(111) gives rise to distinct phases whose characteristics have been examined in real space by scanning tunneling microscopy: a hitherto unrecognized 2D conformational glassy crystal and a 2D orientational glassy crystal, respectively. Herein, the 2D conformational glassy crystalline phase constitutes a novel organization of matter, which combines local conformational disorder and translational symmetry. Both phases are porous and exhibit an arrangement of nanopores that are stabilized by the simultaneous presence of pyridyl-Cu-pyridyl links and C-H***N interactions. In the 2D conformational glassy crystal the framework displayed unprecedented flexibility as probed by the STM tip that modifies the pore shape, a prerequisite for adaptive behavior in host-guest processes.