Conformationally Gated Photoinduced Processes within Photosensitizer - Acceptor Dyads Based on Osmium(II) Complexes with Triarylpyridinio-Functionalized Terpyridyl Ligands. Insights from Experimental Study (Articolo in rivista)

Type
Label
  • Conformationally Gated Photoinduced Processes within Photosensitizer - Acceptor Dyads Based on Osmium(II) Complexes with Triarylpyridinio-Functionalized Terpyridyl Ligands. Insights from Experimental Study (Articolo in rivista) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/ja058357w (literal)
Alternative label
  • Philippe P. Laine; Fethi Bedioui; Frederique Loiseau; Claudio Chiorboli; Sebastiano Campagna. (2006)
    Conformationally Gated Photoinduced Processes within Photosensitizer - Acceptor Dyads Based on Osmium(II) Complexes with Triarylpyridinio-Functionalized Terpyridyl Ligands. Insights from Experimental Study
    in Journal of the American Chemical Society (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Philippe P. Laine; Fethi Bedioui; Frederique Loiseau; Claudio Chiorboli; Sebastiano Campagna. (literal)
Pagina inizio
  • 7510 (literal)
Pagina fine
  • 7521 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 128 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 12 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 23 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR-8601, UniVersite´ Rene´ Descartes, France; Laboratoire de Pharmacologie Chimique et Genetique, CNRS UMR-8151 + INSERM U-640, Ecole Nationale Superieure de Chimie de Paris, France; UniVersita` di Messina, Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Messina, Italy, ISOF-CNR, Sezione di Ferrara, 44100 Ferrara, Italy (literal)
Titolo
  • Conformationally Gated Photoinduced Processes within Photosensitizer - Acceptor Dyads Based on Osmium(II) Complexes with Triarylpyridinio-Functionalized Terpyridyl Ligands. Insights from Experimental Study (literal)
Abstract
  • [(ttpy)Os(tpy-ph-TPH3+)]3+ (2), [(ttpy)Os(tpy-xy-TPH3+)]3+ (3), [(ttpy)Os(tpy-ph-TPH2(NO2)+)]3+(4), and [(ttpy)Os(tpy-xy-TPH2(NO2)+)]3+ (5) are a series of dyads made of an Os(II) bis-tpy complex (tpy) 2,2¢:6¢,2\"-terpyridine) as the photosensitizer (P) and 2,4,6-triarylpyridinium group (TP+) as the electron acceptor (A). These dyads were designed to form charge-separated states (CSS) upon light excitation. Together with analogous Ru(II) complexes (7-10), they have been synthesized and fully characterized. We describe herein how intramolecular photoinduced processes are affected when the electron-accepting strength of A (by nitro-derivatization of TP+) and/or the steric hindrance about intercomponent linkage (by replacing a phenyl spacer by a xylyl one) are changed. Electronic absorption and electrochemical behavior revealed that (i) chemical substitution of TP+ (i.e., TP+-NO2) has no sizable influence on P-centered electronic features, (ii) reduction processes located on TP+ depend on the intercomponent tilt angle. Concerning excited-state properties, photophysical investigation evidenced that phosphorescence of P is actually quenched in dyads 4 and 5 only. Ultrafast transient absorption (TA) experiments allowed attributing the quenching in conformationally locked dyad 5 to oxidative electron transfer (ET) from the 3MLCT level to the TP+-NO2 acceptor (kel ) 1.1 ? 109 s-1). For 4, geometrically unlocked, the 3MLCT state was shown to first rapidly equilibrate (reversible energy transfer; keq ? 2 ? 109 s-1) with a ligand centered triplet state before undergoing CSS formation. Thus, the pivotal role of conformation in driving excited-state decay pathways is demonstrated. Also, inner P structural planarization as a relaxation mode of the 3MLCT states has been inferred from TA experiments. (literal)
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