Effect of structure on the reduction potentials of films of constitutional isomers of iron-sulfur cluster core dendrimers.

The thermodynamic redox potentials of films of constitutional isomers of iron-sulfur cluster core dendrimers were measured and compared. It was determined that the primary structure of the dendrimer influences its reduction potential. Dendrimers containing so-called backfolded linkages were more difficult to reduce than their extended analogues. This behavior is rationalized by suggesting that the backfolded isomers pack more tightly around the iron-sulfur cluster, creating a more hydrophobic local microenvironment. Also, all of these molecules are easier to reduce in the film than in dimethyl formamide solution. The variation in redox potential between film and solution environment was compared to that of dendrimers of differing generations and correlated with the amount of hydrophobic dendron surrounding the cluster.