A combined computational and experimental study of
self-assembled silver-based structures known as superlattices has revealed an
unusual and unexpected behavior: arrays of gear-like molecular-scale machines
that rotate in unison when pressure is applied to them.
Computational and experimental studies show that the
superlattice structures, which are self-assembled from smaller clusters of
silver nanoparticles and organic protecting molecules, form in layers with the
hydrogen bonds between their components serving as “hinges” to facilitate the
rotation. Movement of the “gears” is related to another unusual property of the
material: increased pressure on the superlattice softens it, allowing
subsequent compression to be done with significantly less force.