Abstract
Structural, electronic, and optical properties of the thiolate-protected Au-38(SR)(24) cluster are studied by density-functional theory computations (R = CH3 and R = C6H13) and by powder X-ray crystallography (R = C12H25). A low-energy structure which can be written as Au-23@(Au(SR)(2))(3)(Au-2(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold thiolate Au,,(SR), units yields an excellent match between the computed (for R = C6H13) and measured (for R = C12H25) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au-23 core by using a particle-in-a-cylinder model. Although the alkane thiolate ligands are achiral, the chiral structure of the ligand layer yields strong circular dichroism (CD) in the excitations below 2.2 eV for Au-38(SCH3)(24). Our calculated CD spectrum is in quantitative agreement with the previously measured low-energy CD signal of glutathione-protected Au-38(SG)(24). Our study demonstrates a new mechanism for the strong chiral response of thiolate-protected gold clusters with achiral metal cores and ligands.
Original language | English |
---|---|
Pages (from-to) | 8210-8218 |
Number of pages | 9 |
Journal | Journal of the American Chemical Society |
Volume | 132 |
Issue number | 23 |
DOIs | |
Publication status | Published - 16 Jun 2010 |
MoE publication type | A1 Journal article-refereed |
Keywords
- NANOCRYSTAL GOLD MOLECULES
- OPTICAL-ABSORPTION SPECTRA
- DENSITY-FUNCTIONAL THEORY
- SIMPLE METAL-CLUSTERS
- CIRCULAR-DICHROISM
- CATALYTIC-ACTIVITY
- AEROBIC OXIDATION
- CRYSTAL-STRUCTURE
- SODIUM CLUSTERS
- SHELL STRUCTURE