Abstract
A stopped-flow study of electron transfer (ET) through vesicle membranes composed of egg lecithin (phosphatidyl choline) was made. Cetylmethylviologen (N-methyl-N′-hexadecyl-4,4′-bipyridine, CMV) acted as transmembrane redox mediator by transferring electrons from dithionite in the bulk aqueous phase to CMV2+ or ferricyanide in the vesicle interior. Transmembrane ET was observed when viologen was bound only to the outer interface and the overall reaction was second order in viologen radical on the outside ([CMV+]out). Both facts exclude electron tunneling/self-exchange as mechanism. A mechanism is proposed where the rate-determining step is the disproportionation of two viologen radicals initially formed at the outer interface of the vesicle (2CMV+ = CMV0 + CMV2+). CMV0 diffuses rapidly through the membrane and is re-oxidized in the vesicle interior. A brief study of Ru(bpy)3 2+-sensitized, photoinduced transmembrane ET was made, giving further evidence for transmembrane viologen migration. Preliminary results from pulse-radiolytically induced transmembrane ET support the observation that the reaction is second order in [CMV+]out.
| Original language | English |
|---|---|
| Pages (from-to) | 5017-5024 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry |
| Volume | 96 |
| Issue number | 12 |
| Publication status | Published - 1992 |
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- Physical and Theoretical Chemistry
Cite this
Transmembrane electron transfer mediated by a viologen : A mechanism involving diffusion of doubly reduced viologen formed by disproportionation of viologen radical. / Hammarström, Leif; Almgren, Mats; Norrby, Thomas.
In: Journal of Physical Chemistry, Vol. 96, No. 12, 1992, p. 5017-5024.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Transmembrane electron transfer mediated by a viologen
T2 - A mechanism involving diffusion of doubly reduced viologen formed by disproportionation of viologen radical
AU - Hammarström, Leif
AU - Almgren, Mats
AU - Norrby, Thomas
PY - 1992
Y1 - 1992
N2 - A stopped-flow study of electron transfer (ET) through vesicle membranes composed of egg lecithin (phosphatidyl choline) was made. Cetylmethylviologen (N-methyl-N′-hexadecyl-4,4′-bipyridine, CMV) acted as transmembrane redox mediator by transferring electrons from dithionite in the bulk aqueous phase to CMV2+ or ferricyanide in the vesicle interior. Transmembrane ET was observed when viologen was bound only to the outer interface and the overall reaction was second order in viologen radical on the outside ([CMV+]out). Both facts exclude electron tunneling/self-exchange as mechanism. A mechanism is proposed where the rate-determining step is the disproportionation of two viologen radicals initially formed at the outer interface of the vesicle (2CMV+ = CMV0 + CMV2+). CMV0 diffuses rapidly through the membrane and is re-oxidized in the vesicle interior. A brief study of Ru(bpy)3 2+-sensitized, photoinduced transmembrane ET was made, giving further evidence for transmembrane viologen migration. Preliminary results from pulse-radiolytically induced transmembrane ET support the observation that the reaction is second order in [CMV+]out.
AB - A stopped-flow study of electron transfer (ET) through vesicle membranes composed of egg lecithin (phosphatidyl choline) was made. Cetylmethylviologen (N-methyl-N′-hexadecyl-4,4′-bipyridine, CMV) acted as transmembrane redox mediator by transferring electrons from dithionite in the bulk aqueous phase to CMV2+ or ferricyanide in the vesicle interior. Transmembrane ET was observed when viologen was bound only to the outer interface and the overall reaction was second order in viologen radical on the outside ([CMV+]out). Both facts exclude electron tunneling/self-exchange as mechanism. A mechanism is proposed where the rate-determining step is the disproportionation of two viologen radicals initially formed at the outer interface of the vesicle (2CMV+ = CMV0 + CMV2+). CMV0 diffuses rapidly through the membrane and is re-oxidized in the vesicle interior. A brief study of Ru(bpy)3 2+-sensitized, photoinduced transmembrane ET was made, giving further evidence for transmembrane viologen migration. Preliminary results from pulse-radiolytically induced transmembrane ET support the observation that the reaction is second order in [CMV+]out.
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M3 - Article
VL - 96
SP - 5017
EP - 5024
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
SN - 0022-3654
IS - 12
ER -