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Title: Synthesis, Electrochemistry, and Excited-State Properties of Three Ru(II) Quaterpyridine Complexes

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 1A1 → 1MLCT 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 RuIII/II redox couples. In 0.1 M trifluoroacetic acid (TFA), 1 and 2 undergo aquation to give [RuII(qpy)(OH2)2]2+, as evidenced by the appearance of waves for the couples [RuIII(qpy)(OH2)2]3+/[RuII(qpy)(OH2)2]2+, [RuIV(qpy)(O)(OH2)]2+/[RuIII(qpy)(OH2)2]3+, and [RuVI(qpy)(O)2]2+/[RuIV(qpy)(O)(OH2)]2+ in cyclic voltammograms.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Department of Chemistry, University of North Carolina at Chapel Hill, CB 3290, Chapel Hill, North Carolina 27599-3290, United States
Publication Date:
Grant/Contract Number:
SC0001011; AC05- 06OR23100
Type:
Published Article
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 120; Journal Issue: 11; Related Information: UNC partners with University of North Carolina (lead); Duke University; University of Florida; Georgia Institute of Technology; University; North Carolina Central University; Research Triangle Institute; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Research Org:
Energy Frontier Research Centers (EFRC) (United States). Center for Solar Fuels (UNC EFRC)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), hydrogen and fuel cells, electrodes - solar, charge transport, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly)
OSTI Identifier:
1241400
Alternate Identifier(s):
OSTI ID: 1387513