Achieving one-step molecular photogearing in a minimal light-driven molecular motor

Abstract

The last decades have seen a wealth of progress in the design and synthesis of molecular motors for converting light energy into directed rotary motion around a double bond. Yet, realizing the full potential of these systems in the field of artificial molecular machines will inevitably require a breakthrough in the formidable challenge to construct molecular photogears for transmitting such motion through space and onto a remote single-bond axis, without losing control of the direction of rotation. Here, we unveil a surprisingly straightforward mechanism for achieving this goal in a single photochemical step by incorporating a propeller-shaped barrelene motif into the protonated Schiff-base skeleton of a minimal light-driven molecular motor. Corroborating the mechanism by state-of-the-art computational modeling, our study also identifies strategies for optimizing the photogearing efficiency through modulation of steric interactions. Overall, the results of this work help establish a new route for constructing molecular photogears by combining molecular-motor and propeller-shaped structures.