The Influence of Strain on the Rotation of an Artificial Molecular Motor

In artificial small-molecule machines, molecular motors can be used to perform work on coupled systems by applying a mechanical load—such as strain—that allows for energy transduction. Here, we report how ring strain influences the rotation of rotary motor. Bridging two halves motor with alkyl tethers varying sizes yields macrocycles that constrain motor's movement. Increasing size methylene increments increases mobility stepwise and fine-tuning in system. Small (8–14 units) only undergo photochemical E/Z isomerization. Larger (16–22 full rotational cycle, but thermal helix inversion is strongly dependent size. This study provides systematic quantitative insight into behavior under load, paving way development complex nanomachinery.