Molecular switchStaff: O. Guillermet, V. Langlais, J. Bonvoisin & S. Gauthier
Ph.D. students & Postdocs: T. Leoni, H. Walch, A. Scheuermann
Commutation of bis-dibenzoylmethanato-copper (C30H22O4Cu) between the neutral square-planar complex and the negatively charged tetrahedral complex.Scanning tunneling microscopy (STM) and dynamic force microscopy in the noncontact mode (nc-afm) are used in combination to investigate the reversible switching between two stable states of a copper complex (see the illustration) 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.
(a)–(e) Sequence of STM images showing the reversible switching of two molecules. The position of the tip above the molecule during the application of the bias voltage is marked by a black circle. (f ) 3D representation of image (b).