Nanocluster Size Evolution Studied by Mass Spectrometry in Room Temperature Au₂₅(SR)₁₈ Synthesis

Abstract

We show that MALDI mass spectrometry, suitable for mixtures, is an indispensable tool in probing the mechanism of nanocluster synthesis enabling positive identification of nanoclusters. The size evolution of the mixture of larger clusters (Au(102), Au(68), Au(38)) to form highly monodisperse Au(25) nanoclusters is demonstrated and probably includes the participation of Au(I) thiolate. The size evolution via structural reconstruction of the larger cores such as 38, approximately 44, 68, and 102 to a Au(25) nanocluster has been discussed.

Investigating the structural evolution of thiolate protected gold clusters from first-principles

“…Recently, Dass et al investigated the etching effects of the thiophenol ligand (-PhS) from a sample of a mixture that contains Au 68 and Au 102 as the precursor species. 106 In contrast to their early study of the etching effect of alkanethiolates (such as -SCH 2 Ph) that leads to the formation of the stable Au 38 (SR) 24 species, 107 the -PhS ligands demonstrate very different etching effects that eventually lead to the formation of a new stable RS-AuNP species, Au 36 (SPh) 23 . 106 The new experimental study reveals that the properties of the thiol ligand may strongly affect the stability and interfacial structure of RS-AuNPs.…”

Toward the Creation of Functionalized Metal Nanoclusters and Highly Active Photocatalytic Materials Using Thiolate-Protected Magic Gold Clusters

“…Note that the different effects of Ag doping were reported for the larger Au 38 (SR) 24 and Au 144 (SR) 60 clusters. Dass et al studied the effect of Ag doping on the optical absorption spectra of Au 38 (SR) 24 and Au 144 (SR) 60 and reported that the peak structure diminished steadily with doping number for Au 38 (SR) 24 , while the two plasmon-like absorptions increased steadily for Au 144 (SR) 60 .…”

“…Dass et al studied the effect of Ag doping on the optical absorption spectra of Au 38 (SR) 24 and Au 144 (SR) 60 and reported that the peak structure diminished steadily with doping number for Au 38 (SR) 24 , while the two plasmon-like absorptions increased steadily for Au 144 (SR) 60 . To clarify the size-specific structures and physical properties of the metal clusters and to develop materials with particular characteristics, it is necessary to synthesize individual metal clusters precisely.…”

“…Thiolate-protected gold clusters (Au n (SR) m ) 645 are stable compared with other metal clusters and are promising materials for use in a variety of applications. Extensive investigations have shown that Au n (SR) m clusters, such as Au 25 (SR) 18 , Au 38 (SR) 24 , Au 102 (SR) 44 , and Au 144 (SR) 60 (Figure 1), are particularly stable and have been referred to as magic clusters. 2,8,11,12,21,4658 These magic Au n (SR) m clusters can be synthesized precisely at the atomic level.…”

“…138140), Au 67 (SR) 35 (Ref. 141), Au 102 (SR) 44 , Au 130 -(SR) 50 , Au 144 (SR) 60 , Au 187 (SR) 68 , and Au 333 (SR) 79 (Refs. 142 and 143).…”