A New Heptanuclear Dendritic Ruthenium(ii) Complex Featuring Photoinduced Energy (Articolo in rivista)

Type
Label
  • A New Heptanuclear Dendritic Ruthenium(ii) Complex Featuring Photoinduced Energy (Articolo in rivista) (literal)
Anno
  • 2005-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1002/cphc.200400240 (literal)
Alternative label
  • F. Puntoriero, S. Serroni, M. Galletta, A. Juris, A. Licciardello, C. Chiorboli, S. Campagna, F. Scandola (2005)
    A New Heptanuclear Dendritic Ruthenium(ii) Complex Featuring Photoinduced Energy
    in ChemPhysChem (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • F. Puntoriero, S. Serroni, M. Galletta, A. Juris, A. Licciardello, C. Chiorboli, S. Campagna, F. Scandola (literal)
Pagina inizio
  • 129 (literal)
Pagina fine
  • 138 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 6 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica Universit?à di Messina, Dipartimento di Chimica \"G. Ciamician\", Università? di Bologna Dipartimento di Scienze Chimiche, Universit?à di Catania ISOF-CNR Sezione di Ferrara Dipartimento di Chimica, Università? di Ferrara, (literal)
Titolo
  • A New Heptanuclear Dendritic Ruthenium(ii) Complex Featuring Photoinduced Energy (literal)
Abstract
  • The new heptanuclear ruthenium(ii) dendron, [Cl2Ru{(m-2,3- dpp)Ru[(m-2,3-dpp)Ru(bpy)2]2}2](PF6)12 (1; 2,3-dpp=2,3-bis(2'-pyridyl) pyrazine; bpy=2,2'-bipyridine), was prepared by means of the \"complexes as ligands/complexes as metals\" synthetic strategy, and its absorption spectrum, redox behavior, and luminescence properties were investigated. Compound 1 is a multicomponent species, which contains three different types of chromophores (namely, the {Cl2Ru(m-2,3-dpp)2} core, the {Ru(m-2,3- dpp)3}2+ intermediate, and the {(bpy)2Ru(m-2,3-dpp)}2+ peripheral subunits) and several redox-active sites. The new species exhibits very intense absorption bands in the UV region (e value in the 105-106 m?1cm?1 range) as a result of spin-allowed ligand-centered (LC) transitions, and intense bands in the visible region (e value in the 104-105 m?1cm?1 range) as a result of the various spin-allowed metal-to-ligand charge-transfer (MLCT) transitions. The redox investigation (accomplished by cyclic and differential pulse voltammetry) indicates that 1 undergoes a series of reversible metal-centered oxidation and ligand-centered reduction processes within the potential window investigated (+1.90/?1.40 V vs. the standard calomel electrode, SCE). The assignment of each absorption band and redox process to specific subunits of 1 was achieved by comparison with the properties of smaller multinuclear species of the same family, namely [Cl2Ru{(m-2,3-dpp)Ru(bpy) 2}2]4+ (2), [(bpy)2Ru(m-2,3-dpp)Ru(bpy)2]4+ (4), and [Ru{(m-2,3- dpp)Ru(bpy)2}3]4+ (5). The title compound exhibits luminescence both at room temperature in acetonitrile fluid solution and at 77 K in butyronitrile rigid matrix. The emission is attributed to the triplet MLCT (3MLCT) state involving the core {Cl2Ru(m-2,3-dpp)2} subunit. Interestingly, the 3MLCT levels involving the peripheral {(bpy)2Ru(m-2,3-dpp)}2+ subunits are deactivated by energy transfer to the emitting level, in spite of the presence of interposed high-energy {Ru(m-2,3-dpp)3}2+ components, which, in other dendrimers, acted as \"isolating\" subunits toward energy-transfer processes. Ultrafast experiments on 1 and on the parent species 2 and 5 allowed us to rationalize this behavior and highlight that a sequential two-step electron-transfer process can be held responsible for the efficient overall energy transfer, which offers a way to overcome a limitation in antenna metal dendrimers. (literal)
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