Identifying the Real Chemistry of the Synthesis and Reversible Transformation of AuCd Bimetallic Clusters

Abstract

The capability of precisely constructing bimetallic clusters with atomic accuracy provides exciting opportunities for establishing their structure–property correlations. However, the chemistry (the charge state of precursors, the property of ligands, the amount of dopant, and so forth) dictating the fabrication of clusters with atomic-level control has been a long-standing challenge. Herein, based on the well-defined Au25(SR)18 cluster (SR = thiolates), we have systematically investigated the factors of steric hindrance and electronic effect of ligands, the charge state of Au25(SR)18, and the amount of dopant that may determine the structure of AuCd clusters. It is revealed that [Au19Cd3(SR)18]− can be obtained when a ligand of smaller steric hindrance is used, while Au24Cd­(SR)18 is attained when a larger steric hindrance ligand is used. In addition, negatively charged [Au25(SR)18]− is apt to form [Au19Cd3(SR)18]− during Cd doping, while Au24Cd­(SR)18 is produced when neutral Au25(SR)18 is used as a precursor. Intriguingly, the reversible transformation between [Au19Cd3(SR)18]− and Au24Cd­(SR)18 is feasible by subtly manipulating ligands with different steric hindrances. Most importantly, by introducing the excess amount of dopant, a novel bimetallic cluster, Au4Cd4(SR)12 is successfully fabricated and its total structure is fully determined. The electronic structures and the chirality of Au4Cd4(SR)12 have been elucidated by density functional theory (DFT) calculations. Au4Cd4(SR)12 reported herein represents the smallest AuCd bimetallic cluster with chirality.

Cd Atom Goes into the Interior of Cluster Induced by Directional Consecutive Assembly of Tetrahedral Units on an Icosahedron Kernel

“…However, this metal exchange process most likely occurs during intermolecular interactions, and therefore, intracluster metal exchange, that is, “core sliding”, cannot be identified by comparing the initial and final states. , The key to solving the problem may be the selection of suitable foreign atoms. Cadmium doping has the characteristics of precise doping sites and a smaller number of dopants than doping with other elements, making Cd dopants promising candidates for labeling. − However, in previously reported gold–cadmium nanoclusters, cadmium atoms were only found on the surface of clusters, even with much doping (Scheme a), ,− which hinders the investigation of metal exchange in the inner kernel. To manipulate Cd atoms from the surface to the core of nanoclusters, the assembling strategy is worth considering because it has shown its feasibility in other types of alloying nanoclusters.…”

Insight into the Role of Copper in the Transformation of a [Ag25(2,5-DMBT)16(DPPF)3]+ Nanocluster: Doping or Oxidation

“…Recently, alteration of the compositions of NCs has been recognized as an efficient approach for realizing the structural transformation of NCs. , This strategy can induce a significant structural transformation and make the transformation process more manageable. Therein, doping heterometallic atoms into a NC is more desirable because the synergistic effect between different metals can significantly affect the properties of the doping products even though the initial structural framework has not been changed. − On the basis of the reactions between NCs and heterometallic atoms, alloying NCs have been prepared in previous works, − especially the Au–Cu − or Ag–Cu − NCs. In these cases, copper is chosen because of its economy, and, in addition, it can react with NCs in two ways: (i) replacing the original metal atoms without changing the structural framework of parent NCs (which occurred in most copper-based alloy NCs); − (ii) initiating structural transformation of the parent NC, such as the size conversion from Au 25 to Au 44 and from Au 21 to Au 21– x Cu x in a different configuration. , Recently, related research works focusing on the effect of Cu 2+ on the charge states of NCs have been carried out by our group .…”

Structure and assembly of a hexanuclear AuNi bimetallic nanocluster

“…(ii) How does the novel Au 4 M 2 structure impact its properties? Inspired by the previous works on controlling the atomically precise structure of metal nanoclusters by regulating the electronic and steric effects of ligands, [39][40][41] (2017)(2018)(2019). In December 2019, he started his independent academic career as a professor at Anhui University, China.…”

“…(ii) How does the novel Au 4 M 2 structure impact its properties? Inspired by the previous works on controlling the atomically precise structure of metal nanoclusters by regulating the electronic and steric effects of ligands, 39–41 herein, we obtained a new Au 4 Ni 2 nanocluster by introducing pincer complexes in the synthesis of nanoclusters. This novel Au 4 Ni 2 consists of a square-planar [–PPh 2 –Au–S–Au–] 2 ring and two nickel-pincer arms, featuring abundant inter- and intra-cluster noncovalent interactions.…”