Six state molecular revolver mounted on a rigid platform

• Published in: Nanoscale Vol. 11; no. 18; pp. 915 - 922
• Main Authors: Homberg, Jan, Lindner, Marcin, Gerhard, Lukas, Edelmann, Kevin, Frauhammer, Timo, Nahas, Yasmine, Valášek, Michal, Mayor, Marcel, Wulfhekel, Wulf
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 09.05.2019
• Subjects: Axes of rotation; Metastable state; Molecular motors; Parameter identification; Rotational states; Scanning tunneling microscopy; Switching
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c9nr00259f

The rotation of entire molecules or large moieties happens at 100 ps time scales and the transition process itself is experimentally inaccessible to scanning probe techniques. However, the reversible switching of a molecule between more than two metastable states allows to assign a rotational switching direction. Rotational switching is a phenomenon that is particularly interesting with regard to possible applications in molecular motors. In this work, single tetraphenylmethane molecules deposited on a Au(111) surface were studied in a low temperature scanning tunneling microscope (STM). These molecules comprise rotational axes mounted on a tripodal sulfur-anchored stand and with the STM tip, we were able to induce transitions between six rotational states of the molecular motif. We were able to identify critical parameters for the onset of rotational switching and to characterize the influence of the local environment. The subtle difference between fcc and hcp stacking and the rotational state of neighboring molecules clearly influence the population of the rotational states. The tip of an STM induces transitions between six rotational states in tripodal sulfur-anchored stands with rotational axes.