Rotative Single Molecular Motors on Metallic Surfaces

Abstract

This article gives an overview of the development of rotative molecular motors, with a special emphasis on motors anchored on metallic surfaces. A brief definition of rotative molecular motors is followed by a presentation of the internal and external key factors to take into account when conceiving a molecular motor. In this context, controlling the unidirectionality of the motion is of paramount importance and this chapter describes different strategies to this end, from the molecular design to the study of the rotary motion. The second part is in particular dedicated to pioneering works on molecular motors driven by chemical fuel or light, respectively. These examples also highlight the efforts toward an immobilization of molecular motors, so as to be able to recover their work and transmit it to the macroscale. Finally, we will present two recent examples of motors anchored on metallic surfaces and studied as single molecules with a scanning tunneling microscope (STM). Both molecules were designed to convert electrical energy delivered by the STM tip into a unidirectional rotary motion, but the ruthenium-based motor also proved to work reversibly, which was unprecedented for an artificial molecular motor.