Pinpointing Atoms In Gold Nanoclusters

More than a decade after gold, a model inert metal, showed itself to be catalytically active when prepared as nanosized particles, researchers continue to puzzle over the basis of the metal’s surprising activity. Knowing the positions of every atom in a nanocluster, including the organic ligands that typically cap these structures, would enable researchers to understand the relation between the particles’ structures and functions. But that level of detail, which could speed development of gold-based catalysts, biomedical sensors, and other applications, has remained elusive. X-ray methods typically require large crystals, and microscopy generally cannot resolve ligand atoms because of their low masses. So Xiao Cheng Zeng of the University of Nebraska, Lincoln, and coworkers combined results of an atomic resolution microscopy analysis of Au₆₈(SH)₃₂ clusters reported last year with a new computational technique and thereby pinpointed the positions of all atoms—heavy and light (Sci. Adv. 2015, DOI: 10.1126/sciadv.1400211). The analysis revealed the structures of four highly stable Au₆₈(SH)₃₂ isomers (one shown) and also indicated that these clusters could serve as air-purifying catalysts that convert CO to CO₂.