Aggregation Inducing Reversible Conformational Isomerization of Surface Staple in Au18SR14 Nanoclusters

Abstract

The conformation of molecules and materials is crucial in determining their properties and applications. Here, this work explores the reversible transformation between two distinct conformational isomers in metal nanoclusters. This work demonstrates the successful manipulation of a controllable and reversible isomerization of Au₁₈SR₁₄ within an aqueous solution through two distinct methods: ethanol addition and pH adjustment. The initial driver is the alteration of the solution environment, leading to the aggregation of Au₁₈SR₁₄ protected by ligands with smaller steric hindrance. At the atomic level, the folding mode of the unique Au₄SR₅ staple underpins the observed structural transformation. The reversal of staple conformation leads to color shifting between green and orange-red, and tailors a second emission peak at 725 nm originating from charge transfer from the thiolate to the Au₉ core. This work not only deepens the understanding of the surface structure and dual-emission of metal nanoparticles, but also enhances the comprehension of their isomerization.

Keywords: aggregation; conformational isomerization; dual‐emission; metal nanocluster; surface staple.