Shape Complementarity Modulated Self-Assembly of Nanoring and Nanosphere Hetero-nanostructures

Abstract

Shape complementarity is of paramount importance in molecular recognition, but has rarely been adopted in the selfassembly of colloidal particles, especially in the case of nanoparticles of different shapes. Here, we demonstrated a simple, yet powerful strategy for fabricating gold nanoring-based heterogeneous nanostructures (AuNR-HNs) with well-defined geometries and high yield. The assembly of various geometries of AuNR-HNs is modulated by the shape complementarity of plasmonic nanorings and nanospheres. We also present experimental evidence of dark quadrupolar ring mode excitation in AuNR-HNs through singleparticle optical measurements. Our strategy will be beneficial in the study of nanoparticle assembly, photonic element interaction, and the development of plasmon-based optical devices.

Au Nanorings with Intertwined Triple Rings

“…Similar to ancient convex lenses for fire lighting, where sunlight was concentrated into a small spot, plasmonic nanostructures can trap light at the nanoscale through their intrinsic optical properties. Recently, complex plasmonic nanostructures have become a new paradigm in the field of nanoparticles mainly because of their extraordinary light-trapping ability resulting from strong surface plasmon coupling between different electric dipole sources in a single entity. − Such structures have great potential in a wide range of applications such as surface-enhanced Raman spectroscopy, metamaterials, and bio/chemical sensors. − Localized surface plasmon resonance (LSPR) is a unique optical property of plasmonic nanostructures resulting from collective oscillation of conduction electrons coupled with incident electromagnetic fields. Many recent endeavors have been devoted to fabricating complex plasmonic nanostructures by arranging and overlapping the plasmonic building blocks in a confined space for enhancing and concentrating the LSPR in a small region.…”

Molecular Engineering of Colloidal Atoms

“…Reproduced with permission. [ 169 ] Copyright 2020, American Chemical Society. g) Molecular engineering of complementary lock and key colloidal particles induced by depletion attractions.…”

“…When the sphere is much smaller than the ring, the nanosphere binds to the outer periphery of a nanoring, generating diamond‐ring‐shaped or bowknot‐shaped structures depending on the mixing number ratio of two types of building blocks (Figure 11f). [ 169 ]…”

Plasmonic Cyclic Au Nanosphere Hexamers

“…[ 1–4 ] Another way to control the surface plasmonic characteristics is via the spatial assembly of such building blocks in a rational way, yielding unique arrangement‐dependent optical properties that are different from those of single‐particle counterparts. For example, plasmonic chains [ 5 ] or oligomer‐type assemblies [ 6–8 ] made by spatial placement of Au NSs have been explored in diverse plasmonic applications, ranging from sensing, [ 9 ] bioimaging, [ 10 ] and surface‐enhanced Raman scattering (SERS) [ 11–14 ] to non‐linear optics, such as plasmonic hybridization, [ 15,16 ] and Fano resonance. [ 17 ] To realize such structures, conventional top‐down lithographical approaches using e‐beam lithography with high fidelity as well as high‐precision has been frequently adopted, but this approach often requires delicate hands‐on skills and expensive instruments.…”