Mechanically interlocked gold nanocatenanes

The design of nanostructures is often inspired by the geometries of molecular systems. Inspired by mechanically interlocked catenanes, here we report the synthesis of interlocked plasmonic nanochains, starting from triangular gold nanoplates. The gold nanocatenanes (AuNCats) are prepared in a strategy analogous to the metal-templated synthesis of [2]catenane. We present an analysis of the behaviour of the localized surface plasmon resonance of AuNCats comprising two gold nanorings in terms of D2d spatial symmetry. Moreover, the rocking motion of one nanoring relative to the other causes desymmetrization into D2 symmetry, and induces mechano-helical chirality of an AuNCat as a structural analogy of the [2]catenane, which results in the occurrence of chiroptical responses and remarkably high g factors. As a proof of concept, we constructed a nanoactuator using an AuNCat in tandem with a thermoresponsive polymer. The light-induced thermal actuation of the plasmonic nanomachine transforms rectilinear force into rotational mechanical motion, which enables control of the circular dichroism of the plasmonic nanostructure. We anticipate that mechanically interlocked plasmonic platforms will introduce new classes of nanostructures with unprecedented capabilities. Inspired by molecular catenanes, mechanically interlocked gold nanocatenanes are synthesized starting from triangular gold nanoplates. The interlocked gold nanocatenanes have intriguing optical and mechanical properties, originating from their plasmonic nanomechanical bonds.