One-electron reduction of dihexadecyl phosphate vesicle bound viologens by dithionite ion

Journal Article · Tue Mar 31 23:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00241a017· OSTI ID:6367442

Thompson, D H.P.; Barrette, Jr, W C; Hurst, J K

N-Methyl-N'-alkyl-4,4'-bipyridinium (C/sub n/MV/sup 2 +/) ions bound to dihexadecyl phosphate vesicles are rapidly reduced to radical cations by S/sub 2/O/sub 4//sup 2 -/ in weakly alkaline solutions. For the short-chain viologens investigated (n = 1, 6, 8), the reaction obeys the rate law d(C/sub n/MV/sup +/)/dt = k(C/sub n/MV/sup 2 +/)(S/sub 2/O/sub 4//sup 2 -/)/sup 1/2/. The measured rate constants were identical for preparations in which viologen was added to preformed vesicles and in which vesicles were formed in the presence of viologen, although in the latter systems 10-30% of the viologen was inaccessible to the reductant. For longer chain C/sub n/MV/sup 2 +/ (n = 12, 14, 16, 18, 20), viologen radical formation was biphasic when binding was constrained to the external aqueous-vesicle interface, but it was triphasic when viologen was bound at both interfaces. Where determined, each step was first order in C/sub n/MV/sup 2 +/ and half order in S/sub 2/O/sub 4//sup 2 -/; viologen radical yields were identical in vesicles prepared by either method. The results are interpreted to indicate the simultaneous existence of multiple binding domains for long-chain viologens within the vesicles. Possible structures and relationships to transmembrane redox pathways are briefly discussed.

• Research Organization: Oregon Graduate Center, Beaverton
• DOE Contract Number: AC06-83ER13111
• OSTI ID: 6367442
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMINES
AMMONIUM COMPOUNDS
AZINES
CATIONS
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DISPERSIONS
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
IONS
KINETICS
MEMBRANES
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
PHOSPHATES
PHOSPHORUS COMPOUNDS
PYRIDINES
PYRIDINIUM COMPOUNDS
QUATERNARY COMPOUNDS
RADICALS
REACTION KINETICS
REDOX REACTIONS
REDUCTION
SOLUTIONS