Mechanism governing the formation of atomically precise dithiolate-protected gold nanoclusters

TL;DR

This study explains how to create stable gold nanoclusters using a mix of bidentate and monodentate ligands to avoid unwanted cross-linking.

Contribution

The study identifies the role of ligand flexibility and exchange kinetics in stabilizing gold nanoclusters.

Findings

Bidentate and monodentate ligand combinations prevent inter-cluster cross-linking.

Ligand flexibility and site-specific exchange kinetics are key to forming stable nanoclusters.

The findings enable the design of rigid, well-defined gold nanoclusters.

Abstract

Atomically precise metal nanoclusters (NCs) stabilized by organic ligands are promising functional materials in various fields owing to their unique geometric and electronic structures. However, many such NCs exhibit insufficient stability, e.g., processes such as alloying can induce structural destabilization. Gold (Au) NCs can be protected by introducing multi-site thiolates (SR), which form exceptionally strong Au–S bonds, thus enhancing the stability of the NCs and expanding their practical applicability. However, multi-site SR protection using bidentate ligands often leads to undesirable polymerization due to inter-NC cross-linking. The present study addresses this issue by elucidating the mechanism governing the formation of Au NCs co-protected by both bidentate (SR′S) and monodentate (SR) ligands. The key impacts of ligand flexibility and site-specific exchange kinetics are identified, thereby providing crucial insights to support the strategic design and synthesis of stable, multi-site SR-protected Au NCs with rigid, well-defined architectures.

Multi-site ligands stabilize gold nanoclusters but often cause unwanted inter-cluster cross-linking. This study overcomes this by leveraging bidentate/monodentate ligand combinations and flexibility to synthesize stable, well-defined structures.

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