Regulation of Chirality Transfer and Amplification from Chiral Cysteine to Gold Nanorod Assemblies using Nonchiral Surface Ligands

Abstract

Owing to large chiroptical activity and high tunability, dynamic chiral superstructures of plasmonic nanoparticles have attracted great attention. A useful strategy has been developed to obtain strong plasmonic chiroptical responses (plasmonic circular dichroism, PCD) by adding small chiral thiols on achiral side‐by‐side assemblies of gold nanorods (AuNRs). Despite the critical role of chiral thiols, the impact of achiral surface ligands is yet to be revealed. Herein, the effects of achiral surface ligands are systematically investigated from the viewpoints of counter ion, hydrocarbon chain length, and head group of surfactants. A well‐packed ligand shell is found to be beneficial for the chirality transfer and amplification from adsorbed chiral thiols to rod assemblies. The PCD temperature amplification effect is observed by using different surfactant ligands and reflects the energy cost of rod‐twisting in the assemblies. This study deepens the understanding of chiral plasmonic assemblies driven by small chiral molecules and provides rational design to fabricate such assembly structures.

Cysteine-Mediated Etching of Gold Nanorods by Ferric Ions: Probing Cys Spatial Distribution Features on a Rod Surface

“…The high dependence of the etch pattern on Cys modification suggested that we may obtain Cys adsorption features by decoding the etch pattern. Previously, we found that in achiral side-by-side (SS) assemblies of AuNRs, introduction of chiral Cys could induce huge PCD signals. − Particularly, we observed a volcano-like relationship between the PCD signal and Cys concentration. Notably, strong PCD responses were achieved at a low Cys amount with a narrow concentration window.…”