Rate dependence of electron transfer on donor-acceptor separation and on free enthalpy change. The Ru(bpy)/sub 3//sup 2 +//viologen/sup 2 +/ system
Journal Article
·
· J. Phys. Chem.; (United States)
By attachment of hydrocarbon chains of different lengths to the bipyridyl ligands in Ru(bpy)/sub 3//sup 2 +/ we have adjusted the donor-acceptor separation in the electron-transfer system Ru((C/sub n/H/sub 2n+1/)/sub 2/bpyl/sub 3//sup 2 +//methylviolgen. Two electron-transfer reactions with different ..delta..G are investigated in fluid solution: the quenching of the excited complexes by methylviologen (MV/sup 2 +/) which is exergonic with -0.4 eV and the thermal back electron transfer which is exergonic with -1.7 eV. We observe an exponential decrease of the quenching rate on distance. The back electron transfer is independent of donor-acceptor separation; electron transfer is found to take place at distances of 1.5 nm and more. The results are discussed in terms of a hypothesis on the interdependence of transfer distance and free enthalpy change and compared with current theories. In the framework of the simple classical Marcus model, the Marcus equation relating transfer rate and free enthalpy change is transposed into the Rehm-Weller equation by simple mathematical manipulations and the implications of this are discussed.
- Research Organization:
- Universitaet Hohenheim, Stuttgart, West Germany
- OSTI ID:
- 5568809
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:11; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
AZINES
BIPYRIDINES
COMPLEXES
DATA
DISTANCE
ELECTRON TRANSFER
ENERGY
EXPERIMENTAL DATA
FREE ENTHALPY
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERACTION RANGE
MATHEMATICAL MODELS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PYRIDINES
RUTHENIUM COMPLEXES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPLEXES
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
AZINES
BIPYRIDINES
COMPLEXES
DATA
DISTANCE
ELECTRON TRANSFER
ENERGY
EXPERIMENTAL DATA
FREE ENTHALPY
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERACTION RANGE
MATHEMATICAL MODELS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PYRIDINES
RUTHENIUM COMPLEXES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPLEXES