Recent Advances in Ligand Engineering for Gold Nanocluster Catalysis: Ligand Library, Ligand Effects and Strategies

Abstract

Advances in new ligands in the last decade facilitated in‐depth studies on the property‐relationship of gold nanoclusters and promoted the rational synthesis and related applications of such materials. Currently, more and more new ligands are being explored; thus, the ligand library of AuNCs is being expanded fast, which also enables investigation of ligand effects of AuNCs via direct comparison of different ligating shell with the identical gold core. It is now widely accepted that ligands influence the properties of AuNCs enormously including stability, catalysis, photoluminescence among others. These studies inspired ligand engineering of AuNCs. One of the goals for ligand engineering is to develop ligated AuNC catalysts in which the ligands are able to exert big‐enough influence on electronic and steric control over catalysis as in a transition‐metal or an enzyme system. Although increasing attention is paid to the further expansion of ligand library, the investigation of design principles and strategies regarding ligands are still in their infant stage. This review summarizes the ligands for AuNC synthesis, the ligand effects on stability and catalysis, and recently developed strategies in promoting AuNC catalytic performance via ligand manipulation.

Chemical Flexibility of Atomically Precise Metal Clusters

“…Such unique geometric and electric characteristics pose more unprecedented opportunities for them to display novel chemical-physical properties. 523,524 Examples of these properties include composition-dependent and size-dependent optical and electronic characteristics, 525−533 high emission spanning a broad spectrum from blue to the NIR II region, 534−549 enhanced electrical conductivity 181,550−555 and electrochemical activities, 556−563 magnetism, 564−570 intriguing chirality 43,571−582 and chiroptical activities (refs 44, 45, 68, 74, 154, 172, 538, and 583−589), and a high surface area-to-volume ratio that provides more active sites for catalytic reactions. 26,572,590−606 Additionally, they often exhibit biocompatibility.…”

“…Metal nanoclusters with limited metal atoms have the discrete electronic states related to quantum size effects, which are also regulated by the arrangement and numbers of metal atoms and diverse organic ligands. Such unique geometric and electric characteristics pose more unprecedented opportunities for them to display novel chemical-physical properties. , Examples of these properties include composition-dependent and size-dependent optical and electronic characteristics, − high emission spanning a broad spectrum from blue to the NIR II region, − enhanced electrical conductivity ,− and electrochemical activities, − magnetism, − intriguing chirality ,− and chiroptical activities (refs , , , , , , , and − ), and a high surface area-to-volume ratio that provides more active sites for catalytic reactions. ,,− …”

Fluorescent metal nanoclusters: prospects for photoinduced electron transfer and energy harvesting

“…31–35 Easy synthetic routes, either by reducing the metal ions with thiol ligands or core etching of MNPs, have gained scientific attention across various research areas. 36–39 The high photostability of the MNCs is advantageous over the conventional organic fluorophores that are frequently used as biomarkers. 14,40,41 MNCs are thus widely used in sensing, bio-imaging, photodynamic therapy, electrochemiluminescence, biological tracking, and photovoltaic applications.…”