Magnetism of Atomically Precise Gold and Doped Nanoclusters: Delocalized Spin and Interparticle Coupling

Abstract

The magnetic properties of Au nanoparticles (NPs) have long been an intriguing topic in fundamental research. In the quantum size regime (1–3 nm), Au NPs indeed exhibit distinct magnetism in contrast to diamagnetic gold in bulk or relatively large plasmonic NPs. However, previous studies often give controversial results due to imprecise NPs used in magnetic studies, making it difficult to understand the origin of magnetism in Au NPs. Recent progress has led to atomically precise Au nanoclusters (NCs for differentiation with regular NPs), which can serve as a unique model for studying the delocalized spin in isolated NCs and the spin–spin exchange interaction between NCs in assembled solids. Moreover, such mechanisms are correlated to the atomic structures of the magnetic NCs. The precise formulas of the NCs serve as a clear indicator for magnetism. So far, the Au-thiolate NCs reported to be magnetic, including the doped ones, all contain icosahedral kernel structures, which are facile compared to other structures in adding or removing one electron for endowing magnetism to the NCs. Heteroatom doping in the NCs is an effective method to probe the magnetic mechanism in NCs, such as the origin of magnetic anisotropy, and the counterion tailoring for those charged NCs can also impart magnetism to the initially diamagnetic NCs via stabilizing a particular charge state of the NCs. While only a few cases of NCs have been reported with magnetism thus far, future research on metal NCs (especially in the critical regime between molecular and metallic state) will reveal more fundamentals of magnetism, and the control of spin–spin exchange coupling in nanocluster-assembled solids is particularly promising for tailoring the magnetic functionality of NCs and ultimately finding versatile applications.

Catalytic Conversion of CO2 over Atomically Precise Gold-Based Cluster Catalysts

“…Well-known gold clusters denoted as Au n L m , where L is the ligand and n and m refer to the number of gold atoms and ligands in a cluster, respectively, are typical of atomically precise metal clusters. Through a decade of efforts since the high-quality singe crystal of Au 102 (SR) 44 cluster was obtained and its total structure was successfully solved by SCXRD, atomically precise gold clusters with various structures have been available to the potential applications of optics, magnetics, sensing, imaging, and catalysis. − Notably, gold nanoparticles are important catalysts for various chemical reactions, but almost all of the current studies only give rise to an ensemble average of the catalytic performances because of the structural polydispersity and heterogeneity of gold nanoparticle catalysts. − Therefore, on the basis of definite structures of atomically precise gold clusters, which has long been the number one important task in gold catalysis, unambiguous information on the correlation of structures with catalytic properties and identification of catalytically active sites can be obtained. It is worth pointing out that significant advances have been made in catalysis science, as shown in Figure , including heterogeneous catalysis, homogeneous catalysis, electrochemical catalysis, and photocatalysis.…”

Alkynyl-Protected Ag12Cu4 Cluster with Aggregation-Induced Emission Enhancement

“…Monolayer-protected atomically precise metal clusters have attracted much attention in the past 2 decades since they enabled the study of a distinct size-regime between metal–ligand complexes and metal nanoparticles (typically, >3 nm diameter). , With the development of various synthetic methods and the use of advanced characterization techniques (e.g., single crystal X-ray diffraction and high-resolution mass spectrometry), numerous metal clusters with unique atomic arrangements have been reported. − The clusters possess intriguing optical and physicochemical properties, such as photoluminescence (PL), chemiluminescence, magnetism, and chirality, − which may offer diverse applications. Furthermore, the clusters with determined atomic-level structures are model platforms, which help explore the relationship between structure and properties as well as enable the synthesis of functional nanomaterials. ,,,− …”

Superatomic Three-Center Bond in a Tri-Icosahedral Au36Ag2(SR)18 Cluster: Analogue of 3c-2e Bond in Molecules

“…Characterization of pure and doped gold clusters has been an active area in nanochemistry, as they are potential functional materials with size-specific properties. − Diverse ligand-protected gold clusters have been obtained experimentally, − and efforts have also made to seek understanding of their electronic stabilities. − The staple and bridging ligand motifs, associated with a “divide-and-protect” model, rationalize the bonding rule of their ligand–core interface. Further, the electronic shell of certain spherical gold cores could be explained by the Jellium model of superatom and superatom complexes, − and their closed-shell magic number of valence electrons follows the series 2e, 8e, 18e, 34e.…”