Intrinsically unidirectional chemically fuelled rotary molecular motors – Nature

Biological systems mainly utilize chemical energy to fuel autonomous molecular motors enabling to drive the system out-of-equilibrium¹. Taking inspiration from rotary motors such as the bacterial flagellar motor² and adenosine triphosphate (ATP) synthase³ and building on the great success of light-powered unidirectional rotary molecular motors^4-6, scientists have pursued the design of synthetic molecular motors solely driven by chemical energy^7-13. However, designing artificial rotary molecular motors operating autonomously using a chemical fuel and simultaneously featuring the intrinsic structural design elements to allow full 360° unidirectional rotary motion like ATP synthase remains challenging. Here, we show that a homochiral biaryl Motor-3, with three distinct stereochemical elements, is a rotary motor that undergoes repetitive and unidirectional 360° rotation of the two aryl groups around a single bond axle driven by a chemical fuel. It undergoes sequential ester cyclization, helix inversion and ring-opening, and up to 99% unidirectionality is realized over the autonomous rotary cycle. The molecular rotary motor can be operated in two modes: i) synchronized motion with pulses of a chemical fuel and acid-base oscillations; ii) autonomous motion in the presence of a chemical fuel under slightly basic aqueous conditions. This rotary motor design with intrinsic control over direction of rotation, simple chemical fueling for autonomous motion and near perfect unidirectionality illustrates the potential towards future generations multicomponent machines to perform mechanical functions.