Photooxidation driven formation of Fe-Au linked ferrocene-based single-molecule junctions

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Metal-metal contacts are promising for tunable single-molecule devices.
• Ferrocene is a potential building block for such contacts.
• Previous studies required coordinating ligands for metal-ferrocene bonds.

Purpose of the Study:

• To demonstrate ferrocene-based single-molecule devices with Fe-Au contacts.
• To investigate the role of ferrocene oxidation state in contact formation.
• To explore new contact chemistries beyond main group elements.

Main Methods:

• Fabrication of ferrocene-based single-molecule devices.
• Utilizing photoredox reactions to control ferrocene oxidation.
• Conducting control experiments and density functional theory (DFT) calculations.

Main Results:

• Ferrocene-gold (Fe-Au) interfacial contacts form at room temperature without ligands.
• Ferrocene requires oxidation to ferrocenium (Fe3+) to effectively bind to gold.
• DFT calculations support the proposed binding mechanism.

Conclusions:

• Ferrocene can act as a contact group in metal-metal single-molecule junctions.
• Oxidized ferrocenium is key for forming Fe-Au bonds.
• This work enables light-switchable ferrocene devices and suggests new roles for ferrocenium in synthesis.