Neutral Nickel(II) and Copper(II) Tetraazamacrocyclic Complexes as Molecular Rods Attached to Gold Electrodes

New dithiolated derivatives of neutral Cu-II and Ni-II tetraazamacrocyclic complexes have been synthesized and characterized by spectroscopic and diffractional methods. These rod-shaped molecules were assembled in monocomponent and mixed monolayers on gold electrodes. In the mixed monolayers, the active molecules were embedded in a hexanethiol matrix. The dithiolated complexes are oriented perpendicularly to the electrode, and reveal faster kinetics of electron transfer than those assembled in a single-component monolayer. They appear as protrusions, which are easily addressed by using the STM method. In the presence of a suitable electron acceptor in the solution, the donor properties of the anchored Cu complex were weakened, which revealed donor-acceptor interactions with the monolayer. The peak position in the voltammogram indicates a stronger interaction of the solution-based acceptor with the reduced Cull form than with the Cu-III complex. This suggests the possibility of switching the association on or off by applying an appropriate potential.