Tuning of Single-Molecule Conductance via Regioisomerism and Desilylation in (η⁵-Cp)Co(η⁴-Cb) Complexes

Abstract

Precise control of the single-molecule electron transport is the core task to realize the molecular-based devices. Here, we synthesize a series of regioisomers and achieve bidirectional conductance control in a (η5-Cp)Co(η4-Cb) molecular junction through regioisomerism and molecular editing (desilylation). Desilylation increases the conductance of the para-isomer by ~300% but decreases that of the ortho-isomer by ~65%. Combined DFT and flicker noise spectroscopy reveals that planarization enhances interfacial coupling during desilylation of the para-configuration, while desilylation weakens through-space coupling in the ortho-isomer by reducing LUMO orbital overlap. This work establishes a design strategy that synergistically combines regioisomerism and molecular editing to regulate charge transport in molecular junctions.