Grafting of Organoruthenium Oligomers on Quartz Substrates: Synthesis, Electrochemistry, Optical Properties, and AFM Investigations Mathieu J.-L. Tschan, ² Younes Makoudi, ‡ Fre ´de ´ric Che ´rioux,* ,‡ Frank Palmino, ‡ Isabelle Fabre-Francke, §,| Saı ¨d Sadki, | and Georg Su ¨ss-Fink ² Institut de Chimie, UniVersite ´ de Neucha ˆ tel, Case Postale 158, CH-2009 Neucha ˆ tel, Switzerland, Laboratoire FEMTO-ST, UMR CNRS 6174, UniVersite ´ de Franche-Comte ´ , 32 AVenue de l’ObserVatoire, F-25044 Besanc ¸ on Cedex, France, CEA-LETI-MINATEC, 17 Rue des Martyrs, F-38054 Grenoble Cedex 09, France, and UMR SPraM (CEA, CNRS, UJF), DRFMC CEA de Grenoble, 17 Rue des Martyrs, F-38054 Grenoble Cedex 09, France ReceiVed April 2, 2007. ReVised Manuscript ReceiVed May 23, 2007 A new type of organometallic oligomers has been obtained from the reaction of [(C 6 Me 6 ) 2 Ru 2 H 3 ] + and dithiophenol derivatives. These oligomers are highly ordered because of the steric hindrance around the metal center and the rigidity of the aromatic units. The electrochemical behavior of the monomers and the oligomers has been studied both in reduction and in oxidation modes. The oligomers have been grafted via electrostatic interactions on glass substrates prefunctionalized by self-assembled monolayers (SAMs). The optical properties of the films have also been investigated. Introduction Over the past three decades, arene ruthenium complexes have been extensively studied, 1 one of the driving forces being their catalytic potential. 2 One of the most interesting representatives, the unsaturated dinuclear complex [(C 6 Me 6 ) 2 - Ru 2 (μ 2 -H) 3 ] + , which is isolated as the tetrafluoroborate salt 3 and soluble in both water or organic solvents, turned out to be a versatile starting material for organometallic synthesis. Thus, it has been used as a precursor for the assembly of trinuclear arene ruthenium clusters, 4 and as a building block for conjugated organometallic oligomers. 5 At the same time, conjugated organic oligomers and/or polymers have attracted much attention for their electronic and optical properties and, more recently, for possible applications in nanoelectronics and chemosensing. 6 An extended π-conjugated carbon skeleton is the key feature of such materials. The incorpora- tion of transition metals in conducting polymer systems allows us to expand the functioning and ultimate applications of such materials. 7 Thus, there are many reports on the incorporation of redox-active metal centers into the main chain of conducting structures, in order to develop devices for sensing, for solar energy conversion or for catalytic applications. Moreover, electrostatic lattices formed through electrostatic self-assembly of oppositely charged molecules, oligomers, or polymers have been of great interest. 8 The techniques used for the assembly of such materials involve the sequential adsorption of positively and negatively charged compounds from a solution to produce nanostructured mono- * Corresponding author. Fax: +33 381 853 998, Tel: +33 381 853 951. E-mail: frederic.cherioux@femto-st.fr. ² Universite ´ de Neucha ˆtel. ‡ Universite ´ de Franche-Comte ´. § CEA-LETI-MINATEC. || Universite ´ Joseph Fourrier. (1) (a) Bennett, M. A. Coord. Chem. ReV. 1997, 166, 225. (b) Meister, G.; Rheinwald, G.; Stoeckli-Evans, H.; Su ¨ss-Fink, G. J. Chem. Soc., Dalton Trans. 1994, 3215. (c) Che ´rioux, F.; Thomas, C. M.; Therrien, B.; Su ¨ss-Fink, G. Chem.sEur. J. 2002, 8, 4377. (d) Che ´rioux, F.; Therrien, B.; Su ¨ss-Fink, G. Chem. Commun. 2004, 204. (e) Pinto, P.; Marconi, G.; Heinemann, F. W.; Zenneck, U. Organometallics 2004, 23, 374. 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