Paper SS-MoA3
Liquid-Crystal to Solid-Crystal Phase Transition in Flexible Aryl-Triazole Oligomer Adsorbates at the Liquid / HOPG Interface

Monday, October 29, 2012, 2:40 pm, Room 21

Supramolecular self-assembly at the liquid / solid interface is a powerful strategy for the bottom-up fabrication of complex and well-ordered structures. In order to achieve greater functionality, molecules with functional groups that possess symmetries other than those of the substrate must be included. Here, we explored this idea by integrating the pseudo-C5 triazole moiety into an oligomer through facile synthesis using well-known click chemistry. The molecules initially adsorbed without direct commensuration with HOPG (high oriented pyrolytic graphite) in a lamellar-like liquid-crystalline phase. Subsequent molecular conformational changes are believed to enable a spontaneous phase transition to a more condensed crystalline phase. The crystalline phase forms a dynamic bilayer , in which ripening of the second layer domains was observed. We will present scanning tunneling microscopy (STM) snapshots of this evolution and discuss the dynamics associated with these phase transitions and bilayer formation. Packing models and phase dependence on experimental conditions will be presented. This work lays the foundation for extending the library of self-assembling molecules to develop higher functionality at surfaces.