M. Lieder, C. Schläpfer
Aug 1, 1996
Citations
0
Influential Citations
6
Citations
Journal
Journal of Electroanalytical Chemistry
Abstract
Abstract The reaction of 4,4′-dipyridyl and 1,2-dibromobutane resulted in the formation of a mixture of oligomeric 1,1′-bis-(4-bromobutyl)-4,4′-dipyridinium bromide salts. The mixture contained mainly octa- and hexaquaternary salts. The vitreous carbon electrode modified with a thin layer of this mixture was driven by cyclic voltammetry over its two redox states V2+/+, and V+/0 in LiClO4 solutions. Anion egress upon reduction and ingress upon oxidation was observed. Their movement is coupled with the water molecules forced to move out and into the film by changes of the external osmotic pressure, leading to changes in the film volume. The observed break-in process is probably not directly caused by swelling of the polymer but might be the outcome of the Br− replacement by ClO4−, followed by the acceleration of the charge transfer. The peak potential of the free radical formation is independent of pH. In acidic solution they are likely to react with H+ diffusing into the film. The positively charged free radicals created are more easily reduced than the unprotonated radicals, as indicated by the shift of the peak potential in the positive direction with decreasing pH.