Molecular water-oxidation catalyst derived from ruthenium diaqua bis(2,2'-bipyridyl-5,5'-dicarboxylic acid)
Controlled-potential electrolysis of cis-Ru/sup II/L/sub 2/(OH/sub 2/)/sub 2//sup 2 +/ (where L is 2,2'-bipyridyl-5,5'-dicarboxylic acid) in 0.5 M H/sub 2/SO/sub 4/ solutions leads to the formation of a relatively durable and active molecular water-oxidation catalyst. Detailed analyses by UV-visible absorption spectrophotometry, resonance Raman spectrophotometry, electrochemical measurements, HPLC, and elemental analysis indicate that the water-oxidation catalyst is an oxo-bridged dimer, L/sub 2/(H/sub 2/O)Ru-O-Ru(OH/sub 2/)L/sub 2/. The synthesis, spectrophotometric, and redox properties of the monomeric and dimeric ruthenium complexes have been characterized. The effectiveness of the oxo-bridged complex as a water-oxidation catalyst has been evaluated by electrochemical and spectrophotometric analyses and by determination of oxygen production. This newly discovered homogeneous catalyst is highly effective in mediating the thermal and visible-light-induced generation of oxygen from water. A comparison is made between the monomer and dimer and various analogues of the complexes. The presence of the COOH groups at the 5,5' positions of the bipyridyl ligands correlates with the unusual and favorable properties of cis-RuL/sub 2/(OH/sub 2/)/sub 2/ and L/sub 2/(OH/sub 2/)Ru-O-Ru(OH/sub 2/)L/sub 2/. Dimeric ruthenium complexes of similar structure are also formed during the thermolysis and photolysis of Ru(II) tris(2,2'-bipyridyl-5,5'-dicarboxylic acid), RuL/sub 3//sup 2 +/, in 0.5 M H/sub 2/SO/sub 4/ solutions containing peroxodisulfate.
- Research Organization:
- Ecole Polytechnique Federale, Lausanne, Switzerland
- DOE Contract Number:
- AC02-83CH10093; AC06-83ER13111
- OSTI ID:
- 5571418
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 109:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BIPYRIDINES
CATALYTIC EFFECTS
CHEMICAL PREPARATION
CARBOXYLIC ACIDS
OXYGEN
PRODUCTION
RUTHENIUM COMPLEXES
WATER
OXIDATION
PHOTOCHEMICAL REACTIONS
CATALYSIS
CATALYSTS
ELECTROCHEMISTRY
EXPERIMENTAL DATA
REDOX REACTIONS
SPECTROPHOTOMETRY
AZINES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
ELEMENTS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
NONMETALS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PYRIDINES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry