STM investigation of the structure, dynamics and reactivity of porphyrins on Ag(100)

M. TURNER; O. P. H. VAUGHAN; F. J. WILLIAMS; A. HILLE; N. BAMPOS; J. K. M. SANDERS; R. M. LAMBERT

San Francisco, USA

Conferencia; 232nd ACS National Meeting; 2006

American Chemical Society

Bottom-up fabrication of nanoscopic devices such as gears, ratchets, turnstiles, switches and elevators attracts much attention. Here we are concerned with chemically switchable surface-tethered rotors created by a self-assembly method. These molecular pinwheels were made by mounting Zn tetra-[3,5-di-tert-butylphenyl]porphyrin (Zn-TBPP) molecules (the ?wheels?) on the Ag(100)-adsorbed bi-functional ligand 4-methoxypyridine (the ?axles?). Rotation of all the pinwheels can be switched on or off simultaneously by addition or removal, respectively, of the 4-methoxypyridine axles. Thus a well-chosen ligand can be used to convert a static array of metalloporphyrin molecules into an assembly of surface mounted rotors. Related work on the reversible capping/uncapping of Zn-TBPP by the ligand DABCO is also discussed. Finally, we demonstrate covalent tethering of the protected tetra(thioacetyl) porphyrin to Ag(100) by surface-activated cleavage of the acetyl protecting groups, which disperse over the surface with exposure to oxygen, leaving static porphyrin molecules bound to Ag by thiol linkages.