Year: 2026
Type: preprint
Abstract: Molecular wires incorporating redox units are foundational to single-molecule electronics, yet the molecular designs and environment which govern whether charge-transport proceeds predominantly via phase-coherent quantum tunnelling or thermally activated incoherent hopping remains debated. By synthesising bench-stable Fe(III) ferrocenium wires ( ex-situ oxidation) and comparing their molecular conductance against electrochemically gated Fe(II) analogues ( in-situ oxidation) within scanning tunnelling microscopy break-junctions, we identify distinct experimental signatures of coexisting transport regimes. For both ferrocene and ferrocenium systems, while phase-coherent tunnelling through frontier molecular orbitals dominates at low bias, favourable environmental reorganisation energetics trigger efficient, two-step sequential processes at high biases. These findings resolve a long-standing mechanistic question in metallocene molecular electronics and highlight how two-terminal measurements alone are insufficient to resolve such ambiguities. Our combined electrochemical approach provides a pathway to more robust characterisation of transport phenomena in molecular junctions.
Source: ChemRxiv
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213884100