New structural insights into the stability of Au 22 (SR) 16 nanocluster under ring model guidance.

This study presents thorough structural insights into the stability of crystallized Au 22 (SAdm) 16 (HSAdm = 1-adamantanethiol) nanocluster. With the recently developed Ring Model for describing the interaction between inner gold cores and outer protecting ligands in thiolate-protected gold nanoclusters, the experimental spontaneous transformation from the crystallized Au 22 (SAdm) 16 to Au 21 (SAdm) 15 could be well understood as structurally unfavorable for the current Au 22 (SAdm) 16 and could also be attributed to the weaker aurophilic interaction between the inner Au 4 core and the surrounding rings in Au 22 (SAdm) 16 over that in Au 21 (SAdm) 15 . Furthermore, with the Ring Model and the grand unified model, two new Au 22 (SCH 3 ) 16 isomers with evident lower energies, higher HOMO-LUMO gaps as well as distinct optical properties over the available crystallized isomer were obtained. This study deepens the current knowledge on the structure of the Au 22 (SR) 16 cluster from a new structural point of view and also confirms the validity as well as practicability of the Ring Model in understanding and predicting the stable structures of thiolate-protected gold nanoclusters.