Control of photosensitized electron transfer reactions in organized interfacial systems: vesicles, water-in-oil microemulsions, and colloidal silicon dioxide particles
The separation of photoproducts formed in photosensitized electron transfer reactions is essential for efficient energy conversion and storage. The organization of the components involved in the photoinduced process in interfacial systems leads to efficient compartmentalization of the products. Several interfacial systems, e.g., lipid bilayer membranes (vesicles), water-in-oil microemulsions and a solid SiO/sub 2/ colloidal interface, have been designed to accomplish this goal. An electron transfer across a lipid bilayer membrane leading to the separation of the photoproducts at opposite sides of the membrane is facilitated by establishing a transmembrane potential and organizing the cotransport of cations with specific carriers. In the water-in-oil microemulsion the separation of photoproducts is achieved by means of the hydrophilic-hydrophobic nature of the products. Photosensitized electron transfer reactions analogous to those occurring in the two half-cells are presented. The colloidal SiO/sub 2/ particles provice a charged interface that interacts with charged photoproducts. The photosensitized reduction of a neutral acceptor, propylviologen sulfonate (PVS/sup 0/) by positively charged sensitizers such as Ru(bipy)/sub 3//sup 2 +/ and Zn-tetramethylpyridinium porphyrin, Zu-TMPyP/sup 4 +/, is described. The effect of the SiO/sub 2/ interface is attributed to a high surface potential that results in the separation of the intermediate photoproducts. The quantum yields of the photosensitized reactions are correlated to the interfacial surface potential and the electrical effects of other charged interfaces such as micelles are compared with those of SiO/sub 2/. The possible utilization of the energy stored in the stabilized photoproducts in further chemical reactions is discussed. Special attention is given to the photodecomposition of water as a reaction route. 12 figures.
- Research Organization:
- Univ. of California, Berkeley, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6324292
- Journal Information:
- ACS Symp. Ser.; (United States), Vol. 177
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN PRODUCTION
BIOMIMETIC PROCESSES
BIPYRIDINES
COLLOIDS
ELECTRON TRANSFER
INTERFACES
MEMBRANES
MICROEMULSIONS
OILS
RUTHENIUM COMPLEXES
SILICON OXIDES
WATER
AZINES
CHALCOGENIDES
COMPLEXES
DISPERSIONS
EMULSIONS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PYRIDINES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPLEXES
080106* - Hydrogen- Production- Biosynthesis & Photochemical Processes
400500 - Photochemistry