title: Electrochemical redox control of ferrocene using a supramolecular assembly of ferrocene-linked C(60) derivative and metallooctaethylporphyrin array on a Au(111) electrode.
abstract: Supramolecular assembled layers of ferrocene-linked C(60) derivative (C(60)Fc) and various metal ions coordinated to octaethylporphyrin (MOEP) were formed on the surface of a Au(111) single-crystal electrode by immersing the Au substrate successively into a benzene solution containing MOEP and one containing C(60)Fc molecules. The MOEPs used were zinc(II) (ZnOEP), cobalt(II) (CoOEP), copper(II) (CuOEP), and iron(III) chloride (FeClOEP) of OEP (2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine). The molecules of C(60)Fc directly attached to the Au(111) electrode showed poorly defined electrochemical redox response, whereas a clear electrochemical redox reaction of the ferrocene group in the C(60)Fc molecule was observed at 0.78 V versus reversible hydrogen electrode on ZnOEP, CoOEP, and CuOEP adlayers, but not on the FeClOEP adlayer. Adlattices of the underlying layer and the top layer of C(60)Fc were determined by in situ scanning tunneling microscopy. Adlayer structures of MOEP were independent of the central metal ion; that is, MOEP molecules were arranged hexagonally with two different orientations. Highly ordered C(60)Fc arrays were formed with 1:1 composition on the ZnOEP-, CoOEP-, and CuOEP-modified Au(111) surface, whereas a disordered structure of C(60)Fc was found on the FeClOEP-modified Au(111) surface. The presence of Cl ligand was found to prevent the formation of supramolecularly assembled layers with C(60)Fc molecules, resulting in an ill-defined unclear electrochemical response of the Fc group. The well-defined electrochemical response of the Fc group in C(60)Fc was clearly due to the control of orientation of C(60)Fc molecules.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-04 Aoba, Sendai 980-8579, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Yoshimoto
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Eishi
authors.initials: E
authors.lastname: Tsutsumi
authors.forename: Francis
authors.initials: F
authors.lastname: D'Souza
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito
authors.forename: Kingo
authors.initials: K
authors.lastname: Itaya
mesh_terms: D004563:Electrochemistry; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D037741:Fullerenes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D000075163:Metallocenes; D019216:Metals, Heavy / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005296:Ferrous Compounds; D037741:Fullerenes; D000075163:Metallocenes; D019216:Metals, Heavy; D009942:Organometallic Compounds; D011166:Porphyrins; C488938:octaethylporphyrin; D006046:Gold; C069837:fullerene C60; C004998:ferrocene