Circularly Polarized Luminescence from Atomically Precise Gold Nanoclusters Helically Assembled by Liquid-Crystal Template

Abstract

Chiral plasmonic gold nanoparticles assemblies are known for their strong circular dichroism. However, little is known about the creation of helical assemblies from atomically precise nanoparticles like gold nanoclusters (AuNCs) and the optical properties of the final structures. Herein, a new approach is proposed to helically assemble atomically precise gold nanoclusters and enable circularly polarized luminescence using a liquid-crystal template creating helical nanofilaments. The problem of nanoclusters miscibility is resolved with the liquid crystal matrix by functionalizing nanoclusters with two different ligands: dodecanethiol and specially designed liquid crystal-like ligand. Additionally, the authors explore how functionalization, heating, and helical assembly affect optical properties of gold nanoclusters. The findings prove that assembly incorporating thermotropic liquid crystals and double functionalization of nanocluster surface can be successfully applied to assemble ultrasmall nanoparticles in a helical manner while preserving their atomically precise structure. Moreover, the assembly tunes the nanocluster luminescence and generates new chiroptical effects.