Electron transport through a (terpyridine) ruthenium metallo-surfactant containing a redox-active aminocatechol derivative

Aiming to develop a new class of metallosurfactants with unidirectional electron transfer properties, a (terpyridine) ruthenium complex containing a semiquinone derivative L-2, namely [Ru-III(L-terpy)(L2)Cl]PF6 (1), was synthesized and structurally characterized as a solid and in solution. The electronic and redox behaviour of 1 was studied experimentally as well as by means of DFT methods, and is indicative of significant orbital mixing and overlap between metal and ligands. The complex forms stable Pockels-Langmuir films at the air-water interface and allows for the formation of thin films onto gold electrodes to prepare nanoscale Au vertical bar LB 1 vertical bar Au junctions for current-voltage (I/V) analysis. Complex 1 shows asymmetric electron transfer with a maximum rectification ratio of 32 based on tunnelling through MOs of the aminocatechol derivative.