Plasmonic nanoparticles (NPs) have been widely studied due to their ability to manipulate light, with their eminent optoelectronic properties often correlated to NP symmetry. A robust route towards monodisperse, plasmonic NPs is the seed-mediated method, where preformed NP seeds serve as nucleation sites for depositing secondary material. A hallmark of the seed-mediated method is a transfer a symmetry from seeds to resulting NPs; however, there is a current drive towards synthesizing NPs with different symmetries to provide routes towards new and interesting optoelectronic properties. Recently, chiral gold helicoids of rotational octahedral (432) symmetry have been achieved by seed-mediated overgrowth in which chiral molecules were used as capping agents to induce chirality in the NPs themselves. Interestingly, the chiroptical response of these NPs is much stronger than previous chiral materials, such as chiral assemblies of achiral NPs, due to their intrinsically chiral plasmonic structure. Herein, we present the generation of chiral gold NPs of different underlying symmetries by exploiting seeds of different symmetries. Advanced structural characterization of the overgrowth NPs was achieved by electron microscopy and tomography. The chiroptical behavior of samples was analyzed using circular dichroism (CD) spectroscopy. Experimental and simulated optical properties are then used to inform the effect of chiral features on the chiroptical properties. Overall, this research expands the synthetic toolkit for accessing chiral NPs of different symmetries to achieve new chiroptical properties.

Design and synthesis of chiroptically active gold nanoparticles

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.