Kinetics of triplet decay of water soluble porphyrins. Analysis of ionic strength effects

Autor:	K. Kalyanasundaram, M. Graetzel, V. H. Houlding, L. R. Milgrom
Rok vydání:	1983
Předmět:	Aqueous solution Chemistry General Engineering Analytical chemistry chemistry.chemical_element Zinc Photochemistry Chemical kinetics Reaction rate constant Ionic strength Excited state Flash photolysis Physical and Theoretical Chemistry Triplet state
Zdroj:	The Journal of Physical Chemistry. 87:3175-3179
ISSN:	1541-5740 0022-3654
DOI:	10.1021/j100240a001
Popis:	The triplet decay of zinc tetrakis(N-methyl-4-pyridiniumyl)porphyrin(4+) (ZnTMPyP/sup 4 +/) and zinc tetrakis(N-(propylsulfonato)-4-pyridiniumyl)porphyrin(0) (ZnTPSPyP) in deoxygenated aqueous solution has been studied by laser flash photolysis. Kinetic analysis using a model comprising unimolecular decay, triplet-triplet annihilation, and ground-state quenching yielded rate constants (extrapolated to zero ionic strength) of k/sub uni/ = 350 s/sup -1/, K/sub T-T/ = 1.9 x 10/sup 7/M/sup -1/s/sup -1/, and k/sub GS/ = 5 x 10/sup 6/M/sup -1/s/sup -1/ for ZnTMPyP/sup 4 +/, and k/sub uni/ = 1990 s/sup -1/, k/sub T-T/ = 1.5 x 10/sup 9/ M/sup -1/s/sup -1/, and k/sub GS/ < 10/sup 6/M/sup -1/s/sup -1/ for ZnTPSPyP. Ionic strength dependence of triplet decay was zero for zwitterionic ZnTPSPyP but very strong for ZnTMPyP/sup 4 +/. Results are analyzed in terms of simple Debye-Hueckel theory, and applications to solar energy storage reactions are discussed. 4 figures, 1 table.
Databáze:	OpenAIRE
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