Rotary motion in single-molecule machines

Molecular systems that exhibit controlled or coordinated rotary motion are discussed in this chapter. These systems represent a reproduction of a vari ety of macroscopic mechanical devices on the molecular scale. From gears to a motor, passing through a turnstile, a brake and a ratchet, we describe t heir design, synthesis and dynamic behavior. The importance of molecular mo tors in the biological realm and possible applications in nanotechnology ar e also discussed.