Lateral Translational Diffusion and Electron Transport in Monolayer and Bilayer Assemblies of Amphiphiles at Interfaces

Abstract

Abstract Two novel electrochemical methods of investigation of lateral processes in monolayer and bilayer assemblies are described. The first involves an interdigitated micro-electrode array consisting of fifty pairs of 50 nm thick, 800 nm long, and 4 μm wide electrodes deposited on a glass surface. An amphiphilic bilayer consisting in part of the N-methyl, N′-octadecylbipyridyl molecules is self-assembled in the interelectrode gap. Translational diffusion of the electroactive amphiphile depends on the charge in the head group region and on the fluidity of the assembly controlled by the overall oxidation state of the octadecylbipyridyl. The second method involves 0.1 cm long, 50 nm wide gold micro-band electrodes positioned at the air/water interface and addressing surface monolayer of an octadecylferrocene amphiphile under controlled surface pressure conditions. Electrochemical measurements demonstrate that the lateral translational diffusion and the electron hopping involving ferrocene/ferrocenium sites are the two channels of the lateral charge transport.