Electrochemistry of ferrocenyl dendrimer -: β-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 beta-cyclodextrin (beta CD) were adsorbed at self-assembled monolayers (SAMs) of beta CD (molecular printboards). The dendrimers form a stable monolayer at the beta CD 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 beta CD SAM can be under electrochemical control since Fc forms stable inclusion complexes with beta CD, 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.