6533b82efe1ef96bd129329b

RESEARCH PRODUCT

Au-40(SR)(24) Cluster as a Chiral Dimer of 8-Electron Superatoms: Structure and Optical Properties

Lauri LehtovaaraKuo-juei HuRichard E. PalmerSami MalolaStefan KnoppeThomas BürgiHannu Häkkinen

subject

Models MolecularCircular dichroismIcosahedral symmetryDimerShell (structure)Electrons02 engineering and technologyElectronElectronic structure010402 general chemistry01 natural sciencesBiochemistryCatalysischemistry.chemical_compoundColloid and Surface ChemistryCluster (physics)ta114ChemistryCircular DichroismStereoisomerismGeneral Chemistry021001 nanoscience & nanotechnology0104 chemical sciencesCrystallographyTransmission electron microscopyddc:540Quantum Theory0210 nano-technologyDimerizationOrganogold Compounds

description

We predict and analyze density-functional theory (DFT)-based structures for the recently isolated Au(40)(SR)(24) cluster. Combining structural information extracted from ligand-exchange reactions, circular dichroism and transmission electron microscopy leads us to propose two families of low-energy structures that have a chiral Au-S framework on the surface. These families have a common geometrical motif where a nonchiral Au(26) bi-icosahedral cluster core is protected by 6 RS-Au-SR and 4 RS-Au-SR-Au-SR oligomeric units, analogously to the "Divide and Protect" motif of known clusters Au(25)(SR)(18)(-/0), Au(38)(SR)(24) and Au(102)(SR)(44). The strongly prolate shape of the proposed Au(26) core is supported by transmission electron microscopy. Density-of-state-analysis shows that the electronic structure of Au(40)(SR)(24) can be interpreted in terms of a dimer of two 8-electron superatoms, where the 8 shell electrons are localized at the two icosahedral halves of the metal core. The calculated optical and chiroptical characteristics of the optimal chiral structure are in a fair agreement with the reported data for Au(40)(SR)(24).

10.1021/ja309619nhttps://archive-ouverte.unige.ch/unige:24516