title: Synthesis, Electrochemistry, and Excited-State Properties of Three Ru(II) Quaterpyridine Complexes.
abstract: The complexes [Ru(qpy)LL'](2+) (qpy = 2,2':6',2″:6″,2‴-quaterpyridine), with 1: L = acetonitrile, L'= chloride; 2: L = L'= acetonitrile; and 3: L = L'= vinylpyridine, have been prepared from [Ru(qpy) (Cl)2]. Their absorption spectra in CH3CN exhibit broad metal-to-ligand charge transfer (MLCT) absorptions arising from overlapping (1)A1 → (1)MLCT transitions. Photoluminescence is not observed at room temperature, but all three are weakly emissive in 4:1 ethanol/methanol glasses at 77 K with broad, featureless emissions observed between 600 and 1000 nm consistent with MLCT phosphorescence. Cyclic voltammograms in CH3CN reveal the expected Ru(III/II) redox couples. In 0.1 M trifluoroacetic acid (TFA), 1 and 2 undergo aquation to give [Ru(II)(qpy)(OH2)2](2+), as evidenced by the appearance of waves for the couples [Ru(III)(qpy)(OH2)2](3+)/[Ru(II)(qpy)(OH2)2](2+), [Ru(IV)(qpy)(O)(OH2)](2+)/[Ru(III)(qpy)(OH2)2](3+), and [Ru(VI)(qpy)(O)2](2+)/[Ru(IV)(qpy)(O)(OH2)](2+) in cyclic voltammograms.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Rudd
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: M Kyle
authors.initials: MK
authors.lastname: Brennaman
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Michaux
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Ashford
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Royce W
authors.initials: RW
authors.lastname: Murray
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , CB 3290, Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Meyer