title: An original electrochemical method for assembling multilayers of terpyridine-based metallic complexes on a gold surface.
abstract: A new method based on the electrochemical oxidation of thiols was used to easily generate multilayer assemblies of coordination complexes on a gold surface. For this purpose, two complexes bearing two anchoring groups for surface attachment have been prepared: [Ru(tpySH)(2)](2+) (1) and [Fe(tpySH)(2)](2+) (2) (tpySH = 4'-(2-(p-phenoxy)ethanethiol)-2,2':6',2″-terpyridine). Cyclic voltammetry of 1 in CH(3)CN exhibits two successive oxidation processes. The first is irreversible and attributed to the oxidation of the thiol substituents, whereas the second is reversible and corresponds to the 1 e(-) metal-centered oxidation. In the case of 2 both processes are superimposed. Monolayers of 1 or 2 have been formed on gold electrodes by spontaneous adsorption from micromolar solutions of the complexes in CH(3)CN. SAMs (self-assembled monolayers) exhibit redox behavior similar to the complexes in solution. The high surface coverage value obtained (Γ = 6 × 10(-10) and 4 × 10(-10) mol cm(-2) for 1 and 2, respectively) is consistent with a vertical orientation for the complexes; thus, one thiol is bound to the gold electrode, with the second unreacted thiol moiety exposed to the outer surface. Successive cyclic voltammetry induced a layer-by-layer nanostructural growth at the surface of the SAMs, and this is presumably due to the electrochemical formation of disulfide bonds, where the thiol moieties play a double role of both an anchoring group and an electroactive coupling agent. The conditions of the deposition are studied in detail. Modified electrodes containing both 1 and 2 alternatively can be easily prepared following this new approach. The film proved to be stable, displaying a similar current/voltage response for more than 10 repeating cycles in oxidation up to 0.97 V vs Ag/AgNO(3) (10(-2) M).
authors: Département de Chimie Moléculaire, UMR-5250, Laboratoire de Chimie Inorganique Rédox, Institut de Chimie Moléculaire de Grenoble FR- CNRS-2607, Université Joseph Fourier Grenoble 1/CNRS, BP-53, 38041 Grenoble Cedex 9, France.
authors: Sébastien
authors: S
authors: Liatard
authors: Jérôme
authors: J
authors: Chauvin
authors: Franck
authors: F
authors: Balestro
authors: Damien
authors: D
authors: Jouvenot
authors: Frédérique
authors: F
authors: Loiseau
authors: Alain
authors: A
authors: Deronzier
mesh_terms: D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D009942:Organometallic Compounds; D011725:Pyridines; D006046:Gold; D012428:Ruthenium; D007501:Iron