Intermediate Silver Doping of Au 25 (SR) 18 : Variation of Electronic, Optical, and Chiroptical Properties along Au 25- x Ag x (SH) 18 - ( x = 0-12) Stoichiometry from DFT Calculations.

The silver analogue of the prominent Au 25 (SR) 18 nanocluster reveals the possibility of finding "gold"-like behavior despite their different nature, in addition to the common features among molecular AgNP. Herein, we explore the effect of successive additions of silver atoms reaching an intermediate Ag/Au doping ratio where the parent gold cluster exhibits properties from both elements. Our results show a more favorable situation as the Ag/Au ratio increases along the Au 25- x Ag x (SH) 18 - ( x = 0-12) clusters, with structural distortions mainly centered at the ligand-protected shell. The calculated optical spectrum shows that from the Au 19 Ag 6 species, a plasmon-like peak appears along species with a doping ratio above 25%, where all the silver atoms are located within the M 12 icosahedron. In addition, the chiral properties were explored, showing mild optical activity from the calculated circular dichroism spectra due to the distorted ligand-shell avoiding a centrosymmetric structure. Thus, an intermediate doping ratio ascribed to a specific structural layer can recover inherent properties to both elements in the binary Au 25- x Ag x (SH) 18 - series, suggesting the possibility of having clusters with dual properties at a certain degree of element exchange. This can be useful for further exploration theoretically and synthetically toward different and larger-nuclearity clusters.