A series of intrinsically chiral gold nanocage structures

We present a series of intrinsically chiral gold nanocage structures, Au9n+6, which are stable for n >= 2. These structures consist of an Au-9n tube which is capped with Au-3 units at each end. Removing the Au3 caps, we obtain a series of intrinsically chiral gold nanotube structures, Au-9n, which are stable for n >= 4. The intrinsic chirality of these structures results from the helicity of the gold strands which form the tube and not because an individual Au atom is a chiral center. The symmetry of these structures is C-3 and substructures of gold hexagons with a gold atom in the middle are particularly prominent. We focus on the properties of Au-42 (C-3) and Au-105 (C-3) which are the two smallest gold nanocage structures to be completely tiled by these Au-7 golden-eye substructures. Our main focus is on Au-42 (C-3) since gold clusters in the 40-50 atom regime are currently being investigated in gas phase experiments. We show that the intrinsically chiral Au-42 cage structure is energetically comparable with previously reported achiral cage and compact Au-42 structures. Cage structures are of particular interest because species can be encapsulated (and stabilized) inside the cage and we provide strong evidence that Au-6@Au-42 (C-3) is the global minimum Au-48 structure. The intrinsically chiral gold nanocage structures, which exhibit a range of sizerelated properties, have potential applications in chiral catalysis and as components in nanostructured devices.