A Nanocar and Rotor in One Molecule.

Area of Science:

• Surface science
• Molecular machines
• Nanotechnology

Background:

• Single-molecule machines offer precise control at the nanoscale.
• Adsorption conformation significantly influences molecular behavior on surfaces.

Purpose of the Study:

• Investigate the dual functionality of a zwitterionic single-molecule machine.
• Explore control over molecular motion (rotor vs. nanocar) via surface adsorption.
• Analyze the mechanism of inelastic tunneling excitation for molecular movement.

Main Methods:

• Utilizing Au(111) surfaces for molecular adsorption.
• Applying bias voltage pulses to induce molecular motion.
• Tuning surface coverage to control molecular conformation.
• Investigating inelastic electron tunneling spectroscopy.

Main Results:

• The molecule functions as a unidirectional rotor when anchored.
• The molecule operates as a fast-drivable nanocar when physisorbed.
• Surface coverage dictates the functional state (rotor or nanocar).
• Inelastic tunneling excitation drives both unidirectional rotation and directed nanocar movement under identical conditions.

Conclusions:

• Molecular conformation is a key determinant of single-molecule machine function.
• Surface engineering allows for the selection of distinct nanoscale transport mechanisms.
• Inelastic tunneling is a versatile excitation method for molecular devices.