Controlling Gold Nanoclusters with Atomic Precision for Catalytic Applications

Anindita Das
2019
The major goal of this thesis is synthesis and structure determination of stable, ligand-protected, gold nanoclusters in the ~ 1 nm size regime. These structurally well-characterized clusters are then tested as catalysts in probechemical reactions to gain an atomic-level understanding of size- and/or structure-dependent catalytic pathways.Chapter 2 describes the synthesis and structure determination of a new mixed phosphine/thiolate-protected [Au24(PPh3)10(SC2H4Ph)5X2]+ (where, X= Cl/Br)
more » ... ster. This cluster, which differs by a single Au atom, shows drastic differences in properties from the previously reported biicosahedral [Au25(PPh3)10(SC2H4Ph)5X2]2+ nanocluster protected by the same type and number of phosphine and thiolate ligands. Chapter 3 describes the synthesis and atomic structures of some of the smallest members of the crystallographically characterized thiolate-protected Aun(SR)m clusters, where n and m represent the number of metal atoms and thiolate ligands respectively. These ultra-small nanoclusters lie at the interface between organo-gold complexes and plasmonic gold nanoparticles, i.e. the origin of the first metallic bonds and the nucleation of clusters from organometallic precursors occur in this domain. Total structure determination of thiolateprotectedsmall Au24, Au23 and Au18 clusters has revealed new types of Au core packing structures and surface ligand binding motifs, which offer mechanistic insights into nucleation and size evolution of gold clusters. Chapter 4 discusses the role of protecting ligands in dictating the size and structure of gold clusters. Here, the electronic and steric effects of ligands on the structure and properties of a nanocluster are illustrated, through the case study of a Au36(SR)24 nanocluster. These insigh [...]
doi:10.1184/r1/10069694 fatcat:vf4h2sarxbbl3p7mwuhq5gvjza