A Versatile Strategy for the Controlled Synthesis of Atomically Precise Palladium Nanoclusters.

The study of the structures, applications, and structure-property relationships of atomically precise metal nanoclusters relies heavily on their controlled synthesis. Although great progress has been made in the controlled synthesis of Group 11 (Cu, Ag, Au) metal nanoclusters, the preparation of Pd nanoclusters remains a grand challenge. Herein, a new, simple, and versatile synthetic strategy for the controlled synthesis of Pd nanoclusters is reported with tailorable structures and functions. The synthesis strategy involves the controllable transformations of Pd4(CO)4(CH3COO)4 in air, allowing the discovery of a family of Pd nanoclusters with well-defined structure and high yield. For example, by treating the Pd4(CO)4(CH3COO)4 with 2,2-dipyridine ligands, two clusters of Pd4 and Pd10 whose metal framework describes the growth of vertex-sharing tetrahedra have been selectively isolated. Interestingly, chiral Pd4 nanoclusters can be gained by virtue of customized chiral pyridine-imine ligands, thus representing a pioneering example to shed light on the hierarchical chiral nanostructures of Pd. This synthetic methodology also tolerates a wide variety of ligands and affords phosphine-ligated Pd nanoclusters in a simple way. It is believed that the successful exploration of the synthetic strategy would simulate the research enthusiasm on both the synthesis and application of atomically precise Pd nanoclusters.

Ag10Cu16 nanoclusters with triple-ligand protection: total structure and electronic structure analysis.

Illustrating the molecular structure of metal nanoclusters with the protection of multiple ligands is a prerequisite to understand structure-property relationships of nano or bulk materials with hybrid interfaces. Reported herein is the synthesis, total structure and electronic structure analysis of a new Ag/Cu alloy nanocluster with triple-ligand protection. The cluster with the formula of Ag10Cu16(C8H9S)16(PPh3)4(CF3CO2)8 has been attained in one-pot in a simple way. X-ray single crystal analysis displays its unique metal framework and more importantly rich interface structures. The ligands of phosphine, thioate and carboxylic acid are coordinated to the surface of the cluster in distinctive modes. The electronic structure of the cluster has been revealed by density functional theory, showing that it is a 2-electron superatom with jellium configurations of 1S2. In good accordance with the closure of the geometric and electronic structures, the cluster exhibits moderate stability, which makes it a candidate for further application in many fields.

Decorating an Anticuboctahedral Copper Kernel with Labile Surface Coatings for Controlling Optical and Catalytic Properties.

Manipulating the interfacial/surface structure of ligand-stabilized atomically precise metal nanoclusters (NCs) is one of the central tasks in nanoscience because surface motifs are directly related to key properties of nanomaterials. Although great progress has been made in engineering the surface of gold and silver nanoclusters, parallel studies on lighter copper analogues hitherto remain unexplored. In this work, we report the design, synthesis, and structure of a new class of copper nanoclusters featuring virtually identical kernels but different surface motifs. The four Cu29 nanoclusters share the same Cu13 kernel with unprecedented anticuboctahedral architecture. Finely modulating synthetic parameters endows the Cu13 core with diverse surface structures, thus affording the Cu29 series with labile surface coatings. More interestingly, the slight surface modification results in distinct optical and catalytic properties of the cluster compounds, highlighting the importance of the surface structure in shaping the behaviors of copper nanomolecules. This work not only exemplifies the efficiency of surface engineering for controlling properties of well-defined copper nanoclusters but also provides a new family of Cu materials with a clear molecular structure and controlled surface motifs that hold great promise in studying structure-property relationships.

Chiral copper-hydride nanoclusters: synthesis, structure, and assembly.

An effective strategy is developed to synthesize a novel and stable layered Cu nanocluster using a one-pot reduction method. The cluster, with a molecular formula of [Cu14(tBuS)3(PPh3)7H10]BF4 which has been unambiguously characterized by single crystal X-ray diffraction analysis, exhibits different structures from previously reported analogues with core-shell geometries. In the absence of chiral ligands, the cluster displays intrinsic chirality owing to the non-covalent ligand-ligand interactions (e.g., C-H⋯Cu interactions and C-H⋯π interactions) to lock the central copper core. The interlacing of chiral-cluster enantiomers forms a large cavity, which lays the foundation for a series of potential applications such as drug filling and gas adsorption. Moreover, the C-H⋯H-C interactions of phenyl groups between different cluster moieties promote the formation of a dextral helix and realization of the self-assembly of nanostructures.

An alkynyl-protected Ag13-xCu6+x nanocluster for catalytic hydrogenation.

A novel alkynyl-stabilized silver-copper alloy nanocluster with the composition of [Ag13-xCu6+x(tBuC6H4CC)14(PPh3)6](SbF6)3 was prepared by the (PPh3)2CuBH4-mediated reduction approach. The nanocluster features a centred disordered-octahedral Ag7Cu6 kernel, which is protected by hybrid alkynyl and triphenylphosphine ligands. Structural comparison of this two-electron nanocluster with other alkynyl-capped Ag/Cu ones suggested that the structure of alkynyl ligands played an important role in dictating the structures of the resulting nanoclusters. The title cluster showed high performance in the catalytic hydrogenation of 4-nitrophenol, indicative of the bright future of cluster-based catalysts.