Tuning of single-molecule conductance via regioisomerism and desilylation in (η5-Cp)Co(η4-Cb) complexes

Abstract

Precise control over single-molecule electron transport is the core task in realizing molecular-based devices. Here we synthesize a series of regioisomers and achieve bidirectional conductance control in an (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 reveal 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.