Charge transfer in self-assembled monolayers of molecular conductors containing tripodal anchor and terpyridine-metal redox switching element

•Self-assembled monolayers (SAM)s of Ru- and Os-tripod molecular wires are prepared.•Electron transfer rate constant is higher for Ru-tripod compared to Os-tripod SAM.•Tripodal anchor enables faster electron transfer compared to a bipodal one. This work presents charge transfer characteristics of molecular switches based on [M(terpyridine)2]2+/3+ (M = Ru, Os) electroactive element functionalized by a tripodal thiol-based anchoring platform allowing the formation of self-assembled monolayers (SAMs). It is demonstrated that the Os-tripod compound forms more compact film with less pronounced repulsive interactions among individual [M(terpyridine)2]2+/3+ units compared to Ru-tripod compound. The electron transfer rate constants were determined from cyclic voltammograms and electrochemical impedance spectra by three independent methods. The value of 1.4 × 103 s–1 was obtained for Os-tripod SAM and 1.6 × 103 s–1 for that of Ru-tripod SAM. These values are almost one order of magnitude higher than those reported in the literature for osmium and ruthenium dipodal thiol-based anchors and more than two orders of magnitude higher than those reported for single monopodal aliphatic anchoring groups. [Display omitted]