title: Dinuclear ruthenium(II) polypyridyl complexes containing large, redox-active, aromatic bridging ligands: synthesis, characterization, and intramolecular quenching of MLCT excited states.
abstract: Two new ruthenium(II) polypyridyl dimers containing the large planar aromatic bridging ligands 9,11,20,22-tetraazatetrapyrido[3,2-a:2'3'-c:3' ',2''-l:2''',3'''-n]pentacene (tatpp) and 9,11,20,22-tetraazatetrapyrido[3,2-a:2'3'-c:3'',2' '-l:2''',3'''-n]pentacene-10,21-quinone (tatpq) have been synthesized and characterized by (1)H and (13)C NMR, MALDI mass spectrometry, and elemental analyses. The electronic properties (UV-vis, redox, photophysical) of these dimers are analyzed in the context of orbital calculations (PM3 level) on the bridging ligands. A localized orbital model is proposed in which low-lying acceptor orbitals on the center portion of the ligands effectively quench the Ru(II)-based MLCT emission via a mechanism that can be viewed as intramolecular electron transfer to specific subunits of the bridges.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, USA.
authors.forename: Mahn-Jong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Rama
authors.initials: R
authors.lastname: Konduri
authors.forename: Hongwei
authors.initials: H
authors.lastname: Ye
authors.forename: Frederick M
authors.initials: FM
authors.lastname: MacDonnell
authors.forename: Fausto
authors.initials: F
authors.lastname: Puntoriero
authors.forename: Scolastica
authors.initials: S
authors.lastname: Serroni
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Campagna
authors.forename: Tina
authors.initials: T
authors.lastname: Holder
authors.forename: Gary
authors.initials: G
authors.lastname: Kinsel
authors.forename: Krishnan
authors.initials: K
authors.lastname: Rajeshwar