Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

Metal clusters consisting of fewer than 100 atoms (diameter <2 nm) are highly promising as a new class of building units for functional materials because of their novel and size-dependent properties. Nevertheless, basic and applied studies of metals clusters have been hampered by the lack of specific guidelines for design and precise synthetic methods. This account surveys recent investigations of gold clusters focusing on our effort toward an atomic-level understanding and control of their size-specific properties. We have developed a size-controlled method for synthesizing gold clusters protected by ligands, stabilized by polymers, and supported on solids. Remarkable size-effects on stabilities and various properties including catalysis were observed. Their mechanisms are discussed based on fundamental knowledge of bare gold clusters in the gas phase.