Aiming to develop a new class of metallosurfactants with unidirectional electron transfer properties, a (terpyridine) ruthenium complex containing a semiquinone derivative L2, namely [RuIII(Lterpy)(L2)Cl]PF6 (1), was synthesized and structurally characterized...

Two new metallosurfactants containing the 3d 1 vanadyl(IV) and 3d 3 chromium(III) ions bound to the phenylenediamine-bridged phenolate-rich ligand L N 2 O 2 were designed, deposited as monolayer films on gold electrodes, and probed for directional electron transfer in Au|LB|Au junctions. Both [V�O IV L N 2 O 2 ] (1) and [Cr III (L N 2 O 2 )(MeOH)(H 2 O)]Cl (2) promote current rectification. Through a concerted experimental and computational effort, we compare the behavior of 1 and 2 with that of our previously studied 3d 5 [Fe III (L N 2 O 2 )Cl] (3). Based on the analysis of comprehensive electrochemical, spectroscopic, and microscopy results allied to DFT calculations, we propose distinct mechanisms by which electronic configurations influence the energy gap between the electrode Fermi levels and the different molecular orbitals responsible for electron transport. While the 3d 5 species 3 shows electron transport through the metal-based SOMO located above the Fermi levels of the electrode, the 3d 1 species 1 uses a metal-based SOMO below Fermi, and the 3d 3 species 2 takes advantage of a ligand-based HOMO, which becomes available when a bias is applied.