Colloidal molecules (CMs) assembled from plasmonic nanoparticles are an emerging class of building blocks for creating plasmonic materials and devices, but precise yet reversible assembly of plasmonic CMs remains a challenge. This communication describes the reversible self-assembly of binary plasmonic nanoparticles capped with complementary copolymer ligands into different CMs via halogen bonding interactions at high yield. The coordination number of the CMs is governed by the number ratio of complementary halogen donor and acceptor groups on the interacting nanoparticles. The reversibility of the halogen bonds allows for controlling the repeated formation and disassociation of the plasmonic CMs and hence their optical properties. Furthermore, the CMs can be designed to further self-assemble into complex structures in selective solvents. The precisely engineered reversible nanostructures may find applications in sensing, catalysis, and smart optoelectronic devices.
Keywords: colloidal molecules; halogen bond; nanoparticles; plasmonics; polymer ligands; self-assembly.