Development of an electrically driven molecular motor.

Area of Science:

• Molecular machinery and nanotechnology
• Surface science and interfaces
• Nanoscale electronics

Background:

• Developing molecular machines requires methods to couple individual molecules to external energy sources for directed motion.
• While light- and chemically-powered molecular motors are established, electrically driven examples remain scarce.
• Surface-bound thioethers offer a stable, tunable platform for studying molecular rotation, mimicking biological motors operating at interfaces.

Purpose of the Study:

• To investigate the rotational dynamics of surface-bound thioethers.
• To demonstrate and characterize the first electrically driven single-molecule motor.
• To explore the influence of molecular and electrode chirality on directed rotation.

Main Methods:

• Utilized scanning tunneling microscopy (STM) for real-time, molecular-scale monitoring of rotational events.
• Employed density functional theory (DFT) to complement experimental observations.
• Developed a two-terminal setup to induce molecular rotation via thermal or electron-induced mechanisms.

Main Results:

• Achieved controllable, real-time monitoring of molecular rotation at the single-molecule level.
• Demonstrated directional biasing of electrically driven rotation in a butyl methyl sulfide molecule on a copper surface.
• Established a correlation between the chirality of the molecule, the STM tip, and the direction/rate of rotation.

Conclusions:

• Pioneered the first experimental demonstration of a single-molecule electric motor.
• Highlighted the critical role of symmetry in metal contacts for controlling atomic-scale electrical devices.
• Showcased surface-bound thioethers as a versatile system for studying molecular rotation and developing nanoscale motors.