Heat-enhanced symmetry breaking in dynamic gold nanorod oligomers: the importance of interface control

We reported a surprisingly strong plasmonic circular dichroism (PCD) response in side-by-side (SS) oligomers of gold nanorods (GNRs) just by a simple heat treatment. The maximal anisotropic (g) factor achieved was up to 0.065, one of the largest reported for plasmon-enhanced chiral nanostructures based on a bottom-up strategy. The introduction of chiral thiolated molecules is suggested to guide the symmetry breaking of GNR assemblies and heat treatment provides the necessary energy to assist this process, and thus produces a huge PCD. Furthermore, we first demonstrated the critical role of the non-chiral component (surfactant layer) on the gold nanorod surface in mediating symmetry breaking. Our findings highlight the importance of interface control in the formation of chiral configuration for a plasmonic nanoparticle system. It offers new possibilities for fabricating nanostructures with strong chiroptical activity by the rational design of interface layers.