Dendritic models of redox proteins: X-ray photoelectron spectroscopy and cyclic voltammetry studies of dendritic bis(terpyridine) iron(II) complexes

A series of iron-containing metallodendrimers from the zeroth to the third generation was synthesized and characterized. The iron(rr) ion of these metal complexes is encapsulated within a hydrophobic polyether dendritic envelope. X-ray photoelectron spectroscopy analysis revealed that the bonding environment of the iron atom was essentially the same in dendrimers of different generations. However, cyclic voltammetry studies indicated that the reversibility of the metal redox process decreased in the higher-generation dendrimers. These observations were similar to those of a related electrochemical study conducted on the redox protein cytochrome C, in which the decrease in electron transfer reversibility was explained as a result of the increasing remoteness of the metal ion of the higher-generation dendrimers from the electrode surface.