title: Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces.
abstract: Silicon(111) surfaces have been functionalized with mixed monolayers consisting of submonolayer coverages of immobilized 4-vinyl-2,2'-bipyridyl (1, vbpy) moieties, with the remaining atop sites of the silicon surface passivated by methyl groups. As the immobilized bipyridyl ligands bind transition metal ions, metal complexes can be assembled on the silicon surface. X-ray photoelectron spectroscopy (XPS) demonstrates that bipyridyl complexes of [Cp*Rh], [Cp*Ir], and [Ru(acac)2] were formed on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepared with Ir, X-ray absorption spectroscopy at the Ir LIII edge showed an edge energy as well as post-edge features that were essentially identical with those observed on a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2'-bipyridyl). Charge-carrier lifetime measurements confirmed that the silicon surfaces retain their highly favorable photoelectronic properties upon assembly of the metal complexes. Electrochemical data for surfaces prepared on highly doped, n-type Si(111) electrodes showed that the assembled molecular complexes were redox active. However the stability of the molecular complexes on the surfaces was limited to several cycles of voltammetry.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA. bsb@caltech.edu nslewis@caltech.edu hbgray@caltech.edu.
authors.forename: Judith R C
authors.initials: JR
authors.lastname: Lattimer
authors.forename: James D
authors.initials: JD
authors.lastname: Blakemore
authors.forename: Wesley
authors.initials: W
authors.lastname: Sattler
authors.forename: Sheraz
authors.initials: S
authors.lastname: Gul
authors.forename: Ruchira
authors.initials: R
authors.lastname: Chatterjee
authors.forename: Vittal K
authors.initials: VK
authors.lastname: Yachandra
authors.forename: Junko
authors.initials: J
authors.lastname: Yano
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Brunschwig
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Lewis
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D008024:Ligands; D010084:Oxidation-Reduction; D056951:Photoelectron Spectroscopy; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties; D028561:Transition Elements / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D028561:Transition Elements; D015082:2,2'-Dipyridyl; D012825:Silicon