Quantum‐Sized Gold Nanoclusters: Bridging the Gap between Organometallics and Nanocrystals

Abstract

This Concept article provides an elementary discussion of a special class of large-sized gold compounds, so-called Au nanoclusters, which lies in between traditional organogold compounds (e.g., few-atom complexes, <1 nm) and face-centered cubic (fcc) crystalline Au nanoparticles (typically >2 nm). The discussion is focused on the relationship between them, including the evolution from the Au⋅⋅⋅Au aurophilic interaction in Au(I) complexes to the direct Au-Au bond in clusters, and the structural transformation from the fcc structure in nanocrystals to non-fcc structures in nanoclusters. Thiolate-protected Au(n)(SR)(m) nanoclusters are used as a paradigm system. Research on such nanoclusters has achieved considerable advances in recent years and is expected to flourish in the near future, which will bring about exciting progress in both fundamental scientific research and technological applications of nanoclusters of gold and other metals.

The impacts of nanotechnology on catalysis by precious metal nanoparticles

“…The nanoparticle shape was found to strongly affect the catalytic selectivity: cuboctahedral Pt nanoparticles gave rise to both cyclohexane and cyclohexene, whereas cubic Pt nanoparticles only produced cyclohexane. Interestingly, the selectivities were similar to what were obtained on Pt (111) and (100) single crystals, but the apparent activation energies ( E a ) on nanocrystals were lower than on single crystal Pt surfaces, e.g., E a = 10.9 ± 0.4 kcal/mol for cyclohexane production on cubic nanoparticles, 8.3 ± 0.2 and 12.2 ± 0.4 kcal/mol for respective cyclohexane and cyclohexene production on cuboctahedral nanoparticles.…”

“…Using concave TOH Au [110] B A [111] [100] Tetrahexahedra Concave octahedra Octahedra Figure 11 Core-shell Au-Pd nanocrystals of different morphologies (panels from left to right: THH, concave octahedral, and octahedral shapes). From Ref.…”

“…Current efforts focus on gold [111,112] , but it is feasible to extend to other precious metals. These well-defi ned nanoparticles provide new opportunities for achieving fundamental understanding of metal nanocatalysis.…”

“…These protected nanoclusters are well defi ned on the ultimate atomic scale, as each of them is composed of a precise number of metal atoms ( n ) and of ligands ( m ), with n ranging from approximately tens to hundreds of atoms (equivalent diameter ranging from subnanometer to ∼ 2 nm). Such nanoclusters are vastly different from their larger counterparts -metallic or plasmonic Au nanocrystals (typically > 2 nm) in terms of atomic packing structure and physicochemical properties [111,112] . Relatively small Au n (SR) m nanoclusters (e.g., n < 100) exhibit strong quantum confi nement effects, manifested by the discrete electron energy states and signifi cant band gaps, e.g., 1.3 eV for Au 25 (SR) 18 [114] and 0.9 eV for Au 38 (SR) 24 [115] nanoclusters, as opposed to the quasicontinuous conduction band in plasmonic nanocrystals.…”

Electroplating for Decorative Applications: Recent Trends in Research and Development

“…Examples of nickel containing alloys are nickel copper, nickel silver, and white gold. The release of nickel into the atmosphere during the manufacturing process may lead to respiratory diseases in human and increase the risk of carcinogenicity by inhalation of dust and fumes [108][109][110]. In addition, skin contacts with nickel during cutting and welding operations may lead to dermatitis in allergenic subjects [111,112].…”