Electrochemistry of ferrocenyl dendrimer-beta-cyclodextrin assemblies at the interface of an aqueous solution and a molecular printboard

Water-soluble supramolecular assemblies of redox-active ferrocenyl-decorated (Fc) poly(propylene imine) (PPI) dendrimers and β-cyclodextrin (βCD) were adsorbed at self-assembled monolayers (SAMs) of βCD (“molecular printboards”). The dendrimers form a stable monolayer at the βCD SAM owing to multivalent host−guest interactions. In the present study, dendrimers of generation 1 (4 Fc end groups) up to generation 5 (64 Fc end groups) were investigated. The immobilization of the dendrimers at the βCD SAM can be under electrochemical control since Fc forms stable inclusion complexes with βCD, whereas the oxidized ferrocenium (Fc+) does not. The redox-dependent adsorption process was studied by potential-dependent electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Detailed information was obtained on the adsorption and desorption kinetics, the diffusion constants, and the conformation of the guest dendrimers adsorbed at the host surface.