Mechanisms of Viologen-Mediated Charge Separation Across Bilayer Membranes Deduced from Mediator Permeabilities Full article
Journal |
Journal of the American Chemical Society
ISSN: 0002-7863 , E-ISSN: 1520-5126 |
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Output data | Year: 1992, Volume: 114, Number: 24, Pages: 9498-9503 Pages count : 6 DOI: 10.1021/ja00050a031 | ||||
Tags | VESICLE-BOUND VIOLOGENS; TRANSMEMBRANE ELECTRON-TRANSFER; REDUCTION POTENTIALS; DIFFUSION; ASSEMBLIES; DITHIONITE; CHEMISTRY; KINETICS; RADICALS; ION | ||||
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Affiliations |
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Funding (1)
1 | United States Department of Energy | DE-FG 87ER13664 |
Abstract:
The mobilities of several bipyridinium ions across the hydrocarbon bilayer membranes of dihexadecyl phosphate (DHP) small unilamellar vesicles have been determined by measuring the uptake of 14C-radiolabeled analogs. The N-alkyl-N'-methyl-4,4′-bipyridinium (viologen, CnMV2+) dications and the N-methyl-4,4′-bipyridinium cation were membrane-impermeable. However, the CnMV+ radical cations were permeable, provided that the n-alkyl chain length did not exceed 12 carbon atoms. Diffusion rates obeyed a simple first-order rate law; rate constants for n = 1 and n = 6 were nearly identical, and the constant f or n = 12 was about 3-fold lower. From these values and the measured diffusion potential, the permeability coefficient of the N,N'-dimethyl-4,4′-bipyridinium radical cation was estimated to be 2 × 10-8 cm s-1 at 23 °C. When n = 16, radiolabel exchange was biphasic, with the major fraction of DHP-bound C16MV+ undergoing no transmembrane diffusion. This behavior confirms earlier suggestions, based upon the dynamics of viologen-mediated transmembrane redox reactions, that the short-chain viologens act as mobile charge relays, whereas the long-chain congeners transfer charge primarily by electron tunneling.
Cite:
Lymar S.V.
, Hurst J.K.
Mechanisms of Viologen-Mediated Charge Separation Across Bilayer Membranes Deduced from Mediator Permeabilities
Journal of the American Chemical Society. 1992. V.114. N24. P.9498-9503. DOI: 10.1021/ja00050a031 WOS Scopus РИНЦ
Mechanisms of Viologen-Mediated Charge Separation Across Bilayer Membranes Deduced from Mediator Permeabilities
Journal of the American Chemical Society. 1992. V.114. N24. P.9498-9503. DOI: 10.1021/ja00050a031 WOS Scopus РИНЦ
Dates:
Submitted: | Jan 14, 1992 |
Accepted: | Aug 21, 1992 |
Published print: | Nov 18, 1992 |
Published online: | May 1, 2002 |
Identifiers:
Web of science | WOS:A1992JZ23600031 |
Scopus | 2-s2.0-0000510963 |
Elibrary | 30063120 |
Chemical Abstracts | 1992:640239 |
Chemical Abstracts (print) | 117:240239 |
OpenAlex | W2026773863 |