title: Stepwise preparation and characterization  of molecular wires made of zinc  octaethylporphyrin complexes bridged by  4,4'-bipyridine on HOPG.
abstract: Molecular-scale devices can be made using a step-by-step procedure, in a controllable and highly versatile way. In this report, we describe the growth of molecular wires (MW) from zinc (II) octaethylporphyrin (ZnOEP) assembled on highly oriented pyrolytic graphite (HOPG) by a step-by-step approach using 4,4'-bipyridine (BP) to bridge the porphyrin units, via coordination of the nitrogen atom to zinc. In order to gain an insight into the molecular self-organization of these wires, we carried out a detailed scanning tunnelling microscopy (STM) analysis of each monolayer, using a solid/liquid interface technique, up to a complete ZnOEP/BP/ZnOEP/BP/ZnOEP-assembled structure. The electrical properties of the MWs were assessed by scanning tunnelling spectroscopy (STS) and by current-sensing atomic force microscopy (CS-AFM), showing an increase of electrical resistance with the length of the MW.
authors.affiliation: Instituto de Telecomunicações, Instituto Superior Técnico, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal. quirinatf@gmail.com
authors.forename: Quirina
authors.initials: Q
authors.lastname: Ferreira
authors.forename: Luís
authors.initials: L
authors.lastname: Alcácer
authors.forename: Jorge
authors.initials: J
authors.lastname: Morgado
mesh_terms: D006108:Graphite / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D011725:Pyridines / Q000737:chemistry*
chemical_list: D008665:Metalloporphyrins; D011725:Pyridines; C526613:zinc octaethylporphyrin; D006108:Graphite; C034306:4,4'-bipyridyl