Photogearing – A Concept for Translation of Precise Motions at the Nanoscale

Abstract

Molecular machines offer the prospect of achieving highest precision for the control of dynamic processes at smallest scales. They are constructed from the bottom up and presently a growing number of building blocks such as molecular switches, rotors, and motors are available for exquisite control over local motions. The current challenge now is integrating and transmitting these motions to harness the true potential of functional nano-machinery. Molecular gearing systems allow the integration of multiple motions in a correlated fashion, to translate motions from one locality to another and to change their speed and direction. However, currently no powerful concepts exist to implement active driving of gearing motions at the molecular scale. Herein, we present a light-fueled molecular gearing system and evidence its superiority over passive thermally activated gearing. Translation of a 180° rotation into a 120° rotation is achieved while at the same time the direction of the rotation axis is shifted by 120°. Within such photogearing process, precise motions at the nanoscale can be shifted in direction and decelerated similar to macroscopic bevel-gear operations in an energy consuming way -a necessary prerequisite to employ gearing as an active component in future integrated nanomachinery.