Reductive quenching of the luminescent excited state of tris(2,2 prime -bipyrazine)ruthenium(2+) ion in aqueous solution

Journal Article · Thu Mar 23 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100343a044· OSTI ID:5143607

Neshvad, G; Hoffman, M Z ^[1]

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1. Boston Univ., MA (USA)

The photodynamics of aqueous solutions containing Ru(bpz){sub 3}{sup 2+} (bpz = 2,2{prime}-bipyrazine) and reductive quenchers (D = EDTA (ethylenediaminetetraacetic acid), C{sub 2}O{sub 4}{sup 2{minus}}, TEOA (triethanolamine), ascorbate ion, and thiols (RS{sup {minus}}), e.g., cysteins and glutathione) in the presence and absence of MV{sup 2+} (methylviologen) have been evaluated by the use of time-resolved spectrofluorimetry and pulsed laser flash photolysis as a function of pH, (D), and (MV{sup 2+}); as well, we have determined {Phi}(MV{sup {sm bullet}+}) from the continuous photolyses of these systems. Values of k{sub q} are dependent on pH due to the acid-base properties of the quenchers and range from {approx} 3 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1} for ascorbate ion and deprotonated thiols to {approx}1 {times} 10{sup 7} M{sup {minus}1} s{sup {minus}1} for C{sub 2}O{sub 4}{sup 2{minus}}. The values of {Phi}(MV{sup {sm bullet}+}) from the continuous photolysis correlate very well with the rate constants and efficiencies of the various steps in the mechanism according to the following expression: {Phi}(MV{sup {sm bullet}+}) = {eta}{center dot}{eta}{sub q}{eta}{sub ce} ({eta}{sub red} + {eta}{sub red}{prime}), where {eta} is the efficiency of population of *Ru(bpz){sub 3}{sup 2+}, {eta}{sub q} is the efficiency of quenching of *Ru(bpz){sub 3}{sup 2+}, and {eta}{sub red} and {eta}{sub red}{prime} are the efficiencies of the reactions of Ru(bpz){sub 3}{sup +} and D{sub red} with MV{sup 2+}, respectively. Values of {Phi}(MV{sup {sm bullet}+}) as high as 1.2 have been obtained at pH 4.5 in solutions containing 0.10 M MV{sup 2+} and 0.26 M C{sub 2}O{sub 4}{sup 2{minus}}.

• OSTI ID: 5143607
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:6; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AMINO ACIDS
AQUEOUS SOLUTIONS
AZINES
BIPYRIDINES
CARBOXYLIC ACIDS
CHELATING AGENTS
CHEMICAL REACTIONS
COMPLEXES
DATA
DE-EXCITATION
DECOMPOSITION
DISPERSIONS
EDTA
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
LASERS
LUMINESCENCE
MIXTURES
NEODYMIUM LASERS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PULSE TECHNIQUES
PYRAZINES
PYRIDINES
RADIATIONLESS DECAY
RUTHENIUM COMPLEXES
SOLID STATE LASERS
SOLUTIONS
TRANSITION ELEMENT COMPLEXES