Driving a Third Generation Molecular Motor with Electrons Across a Surface

Area of Science:

• Surface science
• Molecular dynamics
• Nanotechnology

Background:

• Electron tunneling microscopy (STM) enables studying molecular dynamics on surfaces.
• Molecular motors can convert rotational motion into lateral movement.
• The efficiency of electron tunneling in driving molecular motors is not well understood.

Purpose of the Study:

• To investigate the response of a specific molecular motor to inelastic electron tunneling.
• To determine the efficiency and directionality of electron-driven molecular motor action.

Main Methods:

• Utilized scanning tunneling microscopy (STM) on a Cu(111) surface under ultrahigh vacuum at 5 K.
• Examined the effects of inelastic electron tunneling on a molecular motor with overcrowded alkene rotor units.
• Analyzed conformational switching and surface movement induced by electron excitation.

Main Results:

• Vibrational excitation via electron tunneling induced switching between molecular conformations, including enantiomeric states.
• Electronic excitation by tunneling electrons activated motor action and caused surface movement.
• Observed forward movement driven by rotor rotation, but with low translational directionality.

Conclusions:

• Inelastic electron tunneling can control molecular conformation and activate molecular motors.
• Electron tunneling provides a mechanism for driving molecular motors on surfaces.
• While electron-driven rotation causes movement, achieving high directional control remains a challenge.