Plasmonic Chirogenesis from Gold Nanoparticles Superstructures

In this Article, heterodimers with different-sized gold nanoparticles (Au NPs) were fabricated by DNA or sodium chloride (NaCl), which exhibited distinct optical activities. The circular dichroism (CD) band has a magnitude of (−)20 or (+)10 mdeg near the surface plasmonic frequency of Au NPs for DNA or NaCl triggered heterodimers, respectively. Importantly, we provided a new insight into the origins of NPs heterodimers and further investigated the influence factors in NPs dimers. Taking into account that the shapes of the NPs are nonspherical, chiral properties of heterodimers were attributed to the cooperative effect of the small dihedral angle between two adjacent NPs and the plasmonic coupling of NPs, which break the symmetric nature of two uniform spheres; this conclusion was confirmed by 4π full space simulation. Impressively, the chiroptical response was tunable and reversible, and it was achieved by changing the size of building blocks and the temperature. This approach could lead to a further better understanding on the origin of chirality in NPs assemblies and offer rich opportunities for creating new approaches to chiral nanostructures engineering.