Photooxidation of tetraanionic sensitizer ions by dihexadecyl phosphate vesicle-bound viologens

Journal Article · Wed Jan 21 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00236a031· OSTI ID:6948463

Hurst, J K; Thompson, D H.P.; Connolly, J S

Triplet state lifetimes of several photoredox-active anions were shortened by adding N-alkyl-N-methyl-4,4'-bipyridinium (C/sub n/MV/sup 2 +/) ions in the presence of dihexadecyl phosphate (DHP) vesicles. Optical spectroscopic measurements indicate that the predominant reaction mechanism is one-electron oxidative quenching. For (5,10,15,20-tetrakis(4-sulfonatophenyl)porphinato)zinc(II) (ZnTPPS/sup 4 -/) ion, yields of charge-separated product ions are high, so that overall quantum yields exceeding 0.5 redox pairs per photon absorbed can be realized; for tetrakis(diphosphito)diplatinate(II), tris(4,7-bis(4-sulfonato-benzyl)-1,10-phenanthroline)ruthenate(II), and tris(4,4'-dicarboxylato-2,2'-bipyridine)ruthenate(II) yields are markedly less, a consequence of their shorter intrinsic triplet lifetimes and poor cage escape yields. In the absence of vesicles, product formation is negligible because ion pairing of viologens with sensitizers is extensive, giving rise to static quenching of the photoexcited states. The ionic strength dependence of the kinetics of /sup 3/ZnTPPS/sup 4 -/ ion oxidation by C/sub n/MV/sup 2 +/-DHP particles suggests a diffusion-controlled mechanism with electron transfer occurring over a distance of separation approximating the hard-sphere collision diameter of sensitizer and viologen.

• Research Organization: Oregon Graduate Center, Beaverton
• DOE Contract Number: AC06-83ER13111
• OSTI ID: 6948463
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:2; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AZINES
BIPYRIDINES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
DIFFUSION
EFFICIENCY
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
LIFETIME
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PLATINUM COMPLEXES
PYRIDINES
QUANTUM EFFICIENCY
REACTION KINETICS
RUTHENIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
ZINC COMPLEXES