Redox potential selection in a new class of dendrimers containing multipleferrocene centers

The preparation and electrochemical properties of four new dendrimers, comp ounds 1, 2, 3, and 4, containing eight, seven, four, and four ferrocene res idues, respectively, are described. These small dendrimers were prepared wi th the building block bis(ferrocenylmethyl)alkylamine, which contains the t ether -CH2-N(R)-CH2- linking two ferrocene units. The resulting dendrimers are multiferrocene compounds in which the peripheral ferrocene residues are paired. Partial protonation or N-methylation of the connecting nitrogen at oms allows the selection of the ferrocene oxidation potentials between two different values (similar to0.4 and similar to0.6 V vs Ag/AgCl). The observ ed voltammetric pattern for ferrocene oxidation can be reversibly switched among several states depending on the number of protonated centers within e ach dendritic structure. Crystallographic and electrochemical data confirm that the electronic communication between two equivalent ferrocene centers is lessened after protonation or N-methylation of the connecting nitrogens.