Ligand and Solvation Effects on the Structural and Electronic Properties of Small Gold Clusters

Abstract

International audienceThe catalytic, electrochemical, and optical properties of gold clusters and small nanoparticles depend on the cluster size, on the nature of the ligand shell and on the solvent environment. The structural and electronic properties of the neutral and trication bare cluster Au-11 are investigated using density functional theory. We focus on the influence of the cluster charge, the solvent, and the nature and number of the ligands (thiol, thiolate, thiyl radical, phosphine, chloride, and chlorine) on the cluster electronic structure and its geometry, with special attention to the structural motifs present in the metallic core of the different conformers. Single bindings are systematically studied and a comparison with full ligand coverage is discussed. Pure thiyl and phosphine ligand shells as well as mixed thiyl/phosphine shells are considered. This study provides a better understanding of the ligand shell and cooperative effects that could be probed experimentally

Charge Transfer at Hybrid Interfaces: Plasmonics of Aromatic Thiol-Capped Gold Nanoparticles

“…Therefore, from an electronic perspective, the classical view of gold nanocrystals as finite pieces of bulk metal is too restrictive, as already highlighted for smaller gold clusters showing a semiconductor behavior. 48 On the contrary, thiol-grafted gold nanoparticles should be envisioned as genuine organicÀinorganic nanostructures where the hybrid interface can be the locus of extensive charge transfer. This approach enables to envision an alternative development of hybrid nanoplasmonics, where the electronic properties of gold nanodomains will be finely tuned by the controlled injection of electrons from a smartly chosen ligand shell, thus allowing a I drastic economy of gold atoms: 5 nm colloids smartly functionalized have a similar absorption spectrum than 40 nm particles but involve 500 times less atoms.…”

Controlled metal nanostructures: Fertile ground for coordination chemists

“…The addition of ligand tends to modify the active metallic surface and to modify relative rates of catalytic reactions [105]. The recent example of SPOstabilized Au NPs that are active in hydrogenation of aldehydes [112] or that of cyclodextrinmodified Ru/diphosphine NPs whose activity and selectivity in hydrogenation of various [280], [281], [282].…”

Charge Redistribution Effects on the UV–Vis Spectra of Small Ligated Gold Clusters: a Computational Study

“…The spatial organization of the ligands of the same chemical nature in localized domains leads to 'Janus' nanoparticles [36][37][38][39] Previous computational studies on small Au 21 The four clusters, identify as "mixed", "stripe", "Janus 1" and "Janus 2", differ by the arrangement of the thiolates and phosphines in the ligand shell. In the "Janus" clusters, ligands of the same chemical nature are gathered in different hemispheres while they are organized in three stripes in the "stripe" one.…”

“…Despite the similar nature of the excitations in the two clusters, both bands are significantly shifted to the red for Au 25 (SCH 3 ) 18 -. By analyzing the natural charge decomposition in the Au 25 (SCH 3 ) 18 -cluster (reported inTable 3) we find an overall positive charge by summing up the contribution of all the 25 gold atoms, reflecting the electron withdrawing character of the -SR ligands 21,. 49 Nonetheless, the Au 13 central icosahedral core has a partial negative charge of -0.53|e|, more negative than the Au 13 core of [Au 13 (dppe)5 Cl 2 ] 3+ (-0.34|e|).…”