Observation and manipulation of hexa-adamantyl-hexa-benzocoronene molecules by low temperature scanning tunneling microscopy.

Large molecules made of a central hexa-adamantyl-hexa-benzocoronene plateau surrounded by six adamantyl groups have been investigated by low temperature scanning tunneling microscopy and scanning tunneling spectroscopy coupled with image calculations and molecular mechanics. The structure of large self-assembled domains reveals that the intermolecular interactions between adamantyl peripheral groups dominate film growth. At very low coverage, the molecules can exhibit a certain instability for negative bias voltages which induces a partial rotation.

Controlling the charge state of a single redox molecular switch.

Scanning tunneling microscopy and dynamic force microscopy in the noncontact mode are used in combination to investigate the reversible switching between two stable states of a copper complex adsorbed on a NaCl bilayer grown on Cu(111). The molecular conformation in these two states is deduced from scanning tunneling microscopy imaging, while their charge is characterized by the direct measurement of the tip-molecule electrostatic force. These measurements demonstrate that the molecular bistability is achieved through a charge-induced rearrangement of the coordination sphere of the metal complex, qualifying this system as a new electromechanical single-molecular switch.

Self-assembly of fivefold-symmetric molecules on a threefold-symmetric surface.

Buckybowls: The adsorption of penta-tert-butylcorannulene, a molecule with fivefold symmetry, on Cu(111), a surface with threefold symmetry, is investigated by scanning tunneling microscopy complemented by structure calculations. The symmetry mismatch is resolved by the formation of threefold-symmetric subunits consisting of three molecules, which combine with single molecules to form a nearly perfect filling of the plane (see picture).