Aspects of artificial photosynthesis. Photosensitized electron transfer across bilayers, charge separation, and hydrogen production in anionic surfactant vesicles
Photosensitized electron transfer from tris(2,2'-bipyridine)ruthenium cation, Ru(bpy)/sub 3//sup 2 +/, to methylviologen, MV/sup 2 +/, has been investigated in the presence of negatively charged dihexadecyl phosphate, DHP, surfactant vesicles by steady state photolysis, fluorescence quenching, and nanosecond laser flash photolysis. Four different substrate-surfactant vesicle organizations have been used. In system I, Ru(bpy)/sub 3//sup 2 +/ was attached to the outer and MV/sup 2 +/ was placed onto the inner surfaces of DHP vesicles. In system II, MV/sup 2 +/ was attached to the outer and Ru(bpy)/sub 3//sup 2 +/ to the inner surfaces of DHP vesicles. In system III, both Ru(bpy)/sub 3//sup 2 +/ and MV/sup 2 +/ were localized on the outer surfaces of DHP vesicles. In system IV, both Ru(bpy)/sub 3//sup 2 +/ and MV/sup 2 +/ were localized on the inner surfaces of DHP vesicles. Extremely efficient electron transfers have been observed on the surfaces of surfactant vesicles in systems III and IV. Electron transfer from excited Ru(bpy)/sub 3//sup 2 +/ to MV/sup 2 +/ across the bilayers of vesicles in the presence of externally added EDTA in system I resulted in the formation of reduced methylviologen, MV/sup +/., up to 75% conversion with a quantum efficiency of 2.40 x 10/sup -2/. If additionally approx. 10/sup -5/ M PtO/sub 2/ was entrapped in the interiors of DHP vesicles in system I, MV/sup +/. promptly reformed with concomitant hydrogen evolution. Photolysis of this system leads to the net consumption of only EDTA at very low stoichiometric Ru(bpy)/sub 3//sup 2 +/, MV/sup 2 +/, and PtO/sub 2/ concentrations. Dynamics of these processes have been determined and their relevance to photochemical solar energy conversions is discussed.
- Research Organization:
- Texas A and M Univ., College Station
- OSTI ID:
- 6293229
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:10; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
080106 -- Hydrogen-- Production-- Biosynthesis & Photochemical Processes
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKALI METAL COMPLEXES
AMINO ACIDS
AZINES
BIOMIMETIC PROCESSES
BIPYRIDINES
CARBOXYLIC ACIDS
CATALYTIC EFFECTS
CHALCOGENIDES
CHELATING AGENTS
CHEMICAL REACTIONS
COMPLEXES
CONVERSION
DATA
DECOMPOSITION
EDTA
ELECTRON TRANSFER
ENERGY CONVERSION
ESTERS
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROGEN PRODUCTION
INFORMATION
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORIC ACID ESTERS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLATINUM COMPOUNDS
PLATINUM OXIDES
PYRIDINES
RUBIDIUM COMPLEXES
TRANSITION ELEMENT COMPOUNDS