From Monolayer-Protected Gold Cluster to Monolayer-Protected Gold-Sulfide Cluster: Geometrical and Electronic Structure Evolutions of Au60Sn(SR)36 (n=0-12)

Thiolate-monolayer-protected gold clusters are usually formulated as AuNSR[Au(I)-SR](x), where Au-N and SR[Au-(I)-SR](x) (x = 0, 1, 2, ...) are the inner gold core and outer protection motifs, respectively. In this work, we theoretically envision a new family of S-atom-doped thiolate-monolayer-protected gold clusters, namely, Au60Sn(SR)(36) (n = 0-12). A distinct feature of Au60Sn(SR)(36) nanoclusters (NCs) is that they show a gradual transition from the monolayer-protected metal NC to the SR[Au(I)-(SR)](x) oligomer-protected gold-sulfide cluster with the increase of the number of doping S atoms. The possible formation mechanism of the S-atom-doped thiolate-protected gold cluster is investigated, and the size-dependent stability and electronic and optical absorption properties of Au60Sn(SR)(36) are explored using density functional theory (DFT) calculations. It is found that doping of S atom significantly tails the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap and optical absorption properties of thiolate-protected gold cluster, representing a promising way to fabricate new monolayer-protected gold nanoparticles.