Manipulation of large molecules by low-temperature STM: model systems for molecular electronics

The ability of the low-temperature scanning tunneling microscope to manipulate atoms and to build nanostructures with atomic precision can be extended to the manipulation of larger molecules and to selectively modify their internal degrees of freedom. Manipulation experiments on individual molecules show an exciting diversity of physical, chemical, and electronic phenomena. They permit a deeper insight into the quantum electronics of molecular systems and provide important information on the conformational and mechanical properties of single complex molecules. In this article, recent experiments on specially designed molecules will be reviewed, which investigate model systems interesting for the developing of molecular electronics. Starting from the realization of the principle of a molecular switch, going through the possibility of recording the small intramolecular changes inside a complex molecule during its movement, toward the study of the electronic contact between a single molecular wire and a metallic nanoelectrode. (C) 2004 Elsevier B.V. All rights reserved.