Abstract: Some specially designed molecules, such as molecular switches and molecular motors, can reversibly change their geometrical shape when receiving energy from the outside. Such molecular movement enables the active molecule to act as a mechanical actuator. Once orderly assembled in large numbers, these molecules can provide a big driving force, leading to macroscopic actuation behaviors. However, the power of a single molecule remains unknown. The answer to this fundamental question could lead to a deeper understanding of molecular properties and more precise molecular-scale actuators for applications.

Key words: molecular switches; molecular machine; photomechanics; azobenzene