| Abstract
| - Ferrocene has been encapsulated within a symmetric ether-amide dendritic shell and its redoxpotential monitored in a variety of solvents. The dendritic effect generated by the branched shell is differentin different solvents. In less polar, non hydrogen bond donor solvents, attachment of the branched shell toferrocene increases its E1/2, indicating that oxidation to ferrocenium (charge buildup) becomes thermodynamically hindered by the dendrimer, a result explained by the dendrimer providing a less polar mediumthan that of the surrounding electrolyte solution. The effect of electrolyte concentration on redox potentialwas also investigated, and it was shown that the concentration of “innocent” electrolyte has a significanteffect on the redox potential by increasing the overall polarity of the surrounding medium. Dendriticdestabilization of charge buildup is in agreement with the majority of reported dendritic effects. A notableexception to this is provided by the asymmetric ferrocene dendrimers previously reported by Kaifer andco-workers, in which the branching facilitated oxidation, and it is proposed that in this case the dendriticeffect is generated by a different mechanism. Interestingly, in methanol, the new symmetric ferrocenedendrimer exhibited almost no dendritic effect, a result explained by the ability of methanol to interactextensively with the branched shell, generating a more open superstructure. By comparison of all the newdata with other reports, this study provides a key insight into the structure−activity relationships whichcontrol redox processes in dendrimers and also an insight into the electrochemical process itself.
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