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Title: Investigation and optimization of fuel production using dye-based transition metal complexes as charge-transfer intermediates. Annual report, August 1983-August 1984

Technical Report ·
OSTI ID:5909908

Metalloporphyrins offer promising properties for photosensitizing and catalyzing reactions of interest. Because of the detailed understanding of these molecules at a fundamental level, they provide a unique chemical system for investigations of the basic photophysical processes controlling desired chemistries. Therefore, spectroscopic studies of metalloporphyrins in fuel-producing environments were initiated with the goal of determining the factors controlling their photochemical reactivity. Metalloporphyrins perturbed systematically either by structural modifications or by incorporation into various environments were examined by resonance Raman difference spectroscopy, ultraviolet/visible absorption spectroscopy, and other spectroscopic and electrochemical probes. Perturbations on the photosensitizing chromophore resulted in systematic changes in its spectra and its chemical properties. A new theoretical procedure that uses a model of metalloporphyrin electronic states has been applied to quantitatively evaluate systematic differences in the spectra. Efforts to relate metalloporphyrin structure to photochemical activity in an artificial photosynthesis system have begun. For example, the unusually high activity of an anionic tin porphyrin was traced to prevention of formation of inactive complexes by blocking groups attached to the metal. Subsequent studies have shown that blocking groups also prevent aggregation--another inactivating process. Besides this solution system, a number of metalloporphyrin-polymer based systems are being investigated.

Research Organization:
Sandia National Labs., Albuquerque, NM (USA)
OSTI ID:
5909908
Report Number(s):
PB-85-161941/XAB
Country of Publication:
United States
Language:
English