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Titolo:
Spectroelectrochemical investigation of a dinuclear cobalt porphyrin complex with ionic groups in DMSO
Autore:
Yamamoto, K; Nakazawa, S; Matsufuji, A; Taguchi, T;
Indirizzi:
Keio Univ, Fac Sci & Technol, Dept Chem, Yokohama, Kanagawa 2238522, JapanKeio Univ Yokohama Kanagawa Japan 2238522 kohama, Kanagawa 2238522, Japan
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
fascicolo: 3, , anno: 2001,
pagine: 251 - 258
SICI:
1472-7773(2001):3<251:SIOADC>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTRAMOLECULAR ELECTRON-TRANSFER; POSITIVE POTENTIALS; GRAPHITE-ELECTRODES; MOLECULAR-OXYGEN; REDUCTION; O-2; H2O; ELECTROCATALYSIS; ELECTROREDUCTION; CATALYSIS;
Keywords:
catalysis; heterogeneous; electron transfer; porphyrins and analogues; redox; potential; reactions; cobalt;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Yamamoto, K Keio Univ, Fac Sci & Technol, Dept Chem, Yokohama, Kanagawa 2238522, Japan Keio Univ Yokohama Kanagawa Japan 2238522 gawa 2238522, Japan
Citazione:
K. Yamamoto et al., "Spectroelectrochemical investigation of a dinuclear cobalt porphyrin complex with ionic groups in DMSO", J CHEM S DA, (3), 2001, pp. 251-258

Abstract

The dinuclear cobalt porphyrin of (5,10,15,20-tetrakis(N-methyl-4-pyridinio)porphyrinato)cobalt(II) (CoTMPyP) with (5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato)cobaltate(II) (CoTPPS) has allowed spectroelectrochemicalanalysis of electron transfer processes in DMSO. In the II-II valence state it undergoes stepwise two-electron transfer accompanied by a dissociationequilibrium (K-d = 1.3 x 10(-6) M) with redox potentials at -0.37 and -0.17 V vs. Fc-Fc(+). The kinetics of the dissociation allows a snapshot of thespecies present without perturbing the equilibrium distribution. The dissociation in the II-II valence state is promoted by oxidation to the higher valence states due to the increasing charge on the complex and solvation of DMSO at the cobalt. The dissociation constants of the dinuclear porphyrin in the II-III and III-III valence states were determined to be 2.5 x 10(-6) and 5.0 x 10(-6) M, respectively, using Job plots. EXAFS analysis reveals that the Co . . . Co distance in the dimeric porphyrins is 3.37 Angstrom which is not drastically influenced by the valence state in the solid state. The dinuclear cobalt porphyrin complex acts as an excellent catalyst for reduction of oxygen in which the number of electrons transferred was determined to be n = 3.9 based on Koutecky-Levich plots.

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Documento generato il 04/04/20 alle ore 02:44:39