title: Electropolymerizable 2,2'-Carboranyldithiophenes. Structure-Property Investigations of the Corresponding Conducting Polymer Films by Electrochemistry, UV-Visible Spectroscopy and Conducting Probe Atomic Force Microscopy.
abstract: Carborane-functionalized conducting polymer films have been electrogenerated in dichloromethane from the anodic oxidation of ortho- (1), meta- (3) and para-carborane (4) isomers linked to two 2-thienyl units. The corresponding electrochemical response was characterized by a broad reversible redox system corresponding to the p-doping/undoping of the polythiophene backbone, the formal potential of which increased in the order poly(1) < poly(3) < poly(4), from ca. 0.50 to 1.15 V vs Ag/Ag(+) 10(-2) M. From further UV-visible spectroscopy analysis, the optical band gap was estimated at 1.8, 2.0 and 2.2 eV for poly(1), poly(3) and poly(4), respectively. The more conjugated and electroconductive character of poly(1) is ascribed to a more planar conformation of the conjugated backbone resulting from an intramolecular β-β' cyclization reaction in the monomer, consequently yielding a fused conjugated polymer. Molecular modeling calculations using the DFT method support this hypothesis. The surface topography and maps of the conductive domains of the electropolymerized films were evaluated by conducting probe AFM. The three polymers exhibit fairly similar morphological characteristics and a surface roughness of ~2 nm. Current-voltage (I-V) characteristics of conducting AFM tip-carborane polymer-ITO junctions showed that poly(1) had the highest conductivity.
authors.affiliation: CNRS UMR 6226, Sciences Chimiques de Rennes, Matière Condensée et Systèmes Electroactifs (MaCSE), Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France, and Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Barrière
authors.forename: Bruno
authors.initials: B
authors.lastname: Fabre
authors.forename: Erhong
authors.initials: E
authors.lastname: Hao
authors.forename: Zorabel M
authors.initials: ZM
authors.lastname: Lejeune
authors.forename: Euiyong
authors.initials: E
authors.lastname: Hwang
authors.forename: Jayne C
authors.initials: JC
authors.lastname: Garno
authors.forename: Evgueni E
authors.initials: EE
authors.lastname: Nesterov
authors.forename: M Graça H
authors.initials: MG
authors.lastname: Vicente