Surface Chemistry of Atomically Precise Coinage–Metal Nanoclusters: From Structural Control to Surface Reactivity and Catalysis

Abstract

CONSPECTUS:A comprehensive understanding of chemical bonding and reactions at the surface of nanomaterials is of great importance in the rational design of their functional properties and applications. With the rapid development in cluster science, it has become clear that atomically precise metal clusters represent ideal models for resolving various important and/or unsolved issues related to surface science. This Account highlights our recent efforts on the fabrication of ligand-stabilized coinage nanoclusters with atomic precision from the viewpoint of surface coordination chemistry in particular. The successful synthesis of a large variety of metal clusters in our group has greatly benefitted from the development of an effective amineassisted NaBH 4 reduction method. First discussed in this Account is how the introduction of amines in the synthetic protocol enhances the long-term stability and high-yield production of Ag/Cu-based metals in air. Such a method allows the utilization of different organic ligands as surface stabilizing agents to manipulate both the core and surface structures of metal nanoclusters, helping to understand the role of surface ligands in determining the structures of metal nanoclusters. The coordination chemistry of ligands used in the synthesis of metal nanoclusters is crucial in determining their overall shape, metal arrangement, surface ligand binding structure, chirality and also metal exposure. Detailed discussions are given in the following four different systems: (1) The co-use of phosphines and thiolates with rich coordination structures (2 to 4-coordinated) helps to control the formation of a sequence of Ag nanoclusters with a near-perfectly cubic shape; (2) The metal arrangements and surface structures of AuCu clusters highly depend on metal precursors and counter cations used in the synthesis; (3) Metal clusters with intrinsic chirality are readily prepared by introducing chiral ligands or counterions, making it possible to obtain optically active enantiomers and understand the origin of chirality of metal nanoclusters; (4) The variation of metal exposure of the inner metal core of metal nanocluster can be controlled by the surface ligand coordination structure. Such capabilities to manipulate the surface structure of metal nanoclusters allow the creation of model systems for investigating the structure−reactivity relationship of metal nanomaterials. Several important examples are then discussed to highlight the importance of ligand coordination chemistry in tuning the surface reactivity and catalysis of metal nanoclusters. For example, bulky thiolates on Ag are demonstrated to be more labile than small thiolates for making metal nanoclusters with both enhanced ligand exchange capability and catalysis. Alkynyl ligands can be thermally released from metal nanoclusters more easily than thiolates and halides while maintaining the overall structure, thereby serving as ideal systems for understanding the promoting effect of surface stabilizers on catalysis. Finally, we provide ...

The Structure–Property Correlations in the Isomerism of Au21(SR)15 Nanoclusters by Density Functional Theory Study

“…The packing mode of noble metal nanoclusters remarkably affect their physical‐chemical properties . The isomeric nanoclusters with the same number of metal atoms and ligands are the simplest model system to probe the structural effect on properties .…”

“…The packing mode of noble metal nanoclustersr emarkably affect their physical-chemical properties. [10,[33][34][35] The isomeric nanoclustersw ith the same number of metal atoms and ligands are the simplest model system to probe the structural effect on properties. [15,36] For example, the distinct UV/Vis spectra of isomeric nanoclusters( such as in the group of Pt 1 Ag 28 -1/ 2 [19] and Au 30 -1/2 [29,30] )d emonstrate the sensitivity of the optical adsorption characteristict ot he atomic packing mode.…”

Rendering hydrophobic nanoclusters water-soluble and biocompatible

“…Metal nanoclusters, beneting from their atomically precise structures, fascinating properties, and potential applications, are an emerging class of modular nanomaterials. [1][2][3][4][5][6][7][8][9][10][11] Recent years have witnessed signicant research efforts on the controllable synthesis and the structural determination of metal nanoclusters. Typically, the great nanocluster family encompasses both hydrophobic and hydrophilic clusters.…”

Face‐Centered‐Cubic Ag Nanoclusters: Origins and Consequences of the High Structural Regularity Elucidated by Density Functional Theory Calculations

“…Mid-wayi ns ize betweendiscrete metalc omplexesa nd nanoparticles, [1][2][3][4] ultrasmall (< 2nm) metal nanoclusters( NCs) comprising several to hundreds of metal atoms have attracted a great deal of interest due to their molecular-like properties, [5][6][7][8][9][10][11] such as fluorescence [5,6] and chirality. [7][8][9][10] With the ongoing determination of their precise structures (e.g.,b ys ingle-crystal Xray diffraction), some fantastic structural correlationsw ith atomic packingm odes have been elucidated. [1][2][3][4][12][13][14] For example, Au 13 , [15,16] Au 25 , [17,18] and Au 37 [19] comprising one to three icosahedralb uilding blocks have been successfully prepared and well characterized.…”

“…The slopes of À7.34 and À8.81 indicatet he average binding energy of each (B-A)( Figure 8a)o r( A-B)b uilding block(Figure 8b). The intercepts of À20.18 and À27.06, respectively,c orrespond to the redundant structure of Ag 4 (SR)8 (PR 3 ) 8 in the A-assembled silver NCs and that of Ag 13 (SR) 8 (PR 3 ) 8 in the B-assembled NCs (when n = 0).…”