Mercury-Mediated Attachment of Metal-Sandwich-Based Altitudinal Molecular Rotors to Gold Surfaces

Gold surface attachment of altitudinal molecular rotors provided with ten −HgSCH 2 CH 2 SCH 3 “tentacles” has been monitored with ellipsometry, scanning tunneling microscopy, and X-ray photoelectron spectroscopy (XPS). The rotors appear to adsorb on the gold surface in the intended orientation, with rotor axle parallel to the surface, without any inclination for multilayer growth. According to XPS data, the sulfur-containing tentacles start to be detectably oxidized within hours of exposure to air and can be ultimately removed by washing. The rotor molecules nevertheless remain firmly attached in the desired orientation, apparently due to a direct interaction of their Hg atoms with the gold surface. When the tentacles are simplified to −HgOCOCF 3 substituents, the molecules adhere to the surface as well, but not always in the desired orientation.