Intermolecular Interactions in Mixed Self-Assembled Monolayers of Ferrocene

Electrochemical characterization of mixed self-assembled monolayers (SAMs) of 6-ferrocenyl-1-hexanethiol (FcH) and mercaptoundecanoic acid tyrosinamide (MUATyr) on gold is reported. Single-component SAMs of FcH presented repulsive intermolecular interactions (vG theta(T)= -1.12), while mixed SAMs of FcH/MUATyr (1 : 1) exhibited attractive interactions (vG theta(T)=+0.20), with a homogeneous distribution of both components. Electrochemical kinetic determinations on mixed SAMs of FcH/MUATyr, indicated a secondary electron transfer pathway between the redox centers of both components. Higher amounts of FcH in the mixed SAMs lowered the observed rate of electron transfer of MUATyr. The oxidation of FcH caused an anodic shift of 160 mV in the voltammetric wave of MUATyr.