One-electron reduction of tris(2,2 prime -bipyrimidine)ruthenium(2+) ion in aqueous solution. A photochemical, radiation chemical, and electrochemical study

Journal Article · Thu Aug 10 00:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100353a028· OSTI ID:6971176

Neshvad, G; Hoffman, M Z ^[1]; Mulazzani, Q G; Ciano, M; D'Angelantonio, M ^[2]; Venturi, M ^[3]

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1. Boston Univ., MA (USA)
2. Istituto di Fotochimica e Radiazioni d'Alta Energia, Bologna (Italy)
3. Istituto di Fotochimica e Radiazioni d'Alta Energia, Bologna (Italy) Univ. di Bologna (Italy)

The reduction of Ru(bpm){sub 3}{sup 2+} in aqueous solution has been investigated by use of photochemical, radiation chemical, and electrochemical techniques. The luminescent excited state of the substrate, *Ru(bpm){sub 3}{sup 2+}, has a lifetime ({tau}{sub 0}) of 0.081 {mu}s and a standard reduction potential of {approximately} 1.2 V; it is quenched by electron donors (D) such as ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEOA), ascorbate ion, deprotonated cysteine, and reduced glutathione with values of k{sub q} that depend on the pH of the solution and the reducing ability of the quencher. The one-electron-reduced species, Ru(bpm){sub 3}{sup +}, is formed in the quenching reaction; it is also produced electrochemically and from the reaction of radiolytically generated CO{sub 2}{sup {center dot}{minus}} with Ru(bpm){sub 3}{sup 2+} (k = 6.7 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}). Ru(bpm){sub 3}{sup +} is a good reducing agent (E{sub ox}{sup 0} = 0.73 V) and reduces MV{sup 2+} (methylviologen) to MV{sup {center dot}+} (k = 1.0 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}). Ru(bpm){sub 3}{sup +} also undergoes protonation; its acidic form (pK{sub a} 6.3) is a milder reducing agent (E{sub ox}{sup 0} = 0.50 V) but is still capable of reducing MV{sup 2+} (k = 1.0 {times} 10{sup 6} M{sup {minus}1} s{sup {minus}1}). Both forms of Ru(bpm){sub 3}{sup +} are unstable with respect to long-term storage; it is likely they engage in disproportionation and/or reaction with the solvent. The continuous photolysis of a solution containing Ru(bpm){sub 3}{sup 2+}, MV{sup 2+}, and a sacrificial reductive quencher (EDTA, TEOA) generates MV{sup {center dot}+}. Values of {eta}{sub ce} of 0.64 and {approximately}0.7 for TEOA and EDTA, respectively, in alkaline solution have been obtained.

• OSTI ID: 6971176
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:16; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
14 SOLAR ENERGY
RUTHENIUM COMPLEXES
ELECTROCHEMISTRY
PHOTOCHEMISTRY
RADIATION CHEMISTRY
AQUEOUS SOLUTIONS
DATA ANALYSIS
EXPERIMENTAL DATA
MEASURING INSTRUMENTS
MEASURING METHODS
REDUCTION
SOLAR CELLS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
DIRECT ENERGY CONVERTERS
DISPERSIONS
EQUIPMENT
INFORMATION
MIXTURES
NUMERICAL DATA
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SOLAR EQUIPMENT
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry
140500 - Solar Energy Conversion