Unraveling the Atomic Structures of the Au₆₈(SR)₃₄ Nanoparticles

The atomic structure prediction of thiolate-protected gold nanoparticle (RS-AuNP) Au 68 (SH) 34 is performed based on the “divide and protect” concept and experimental studies on 14 kDa RS-AuNPs. Four low-lying energy isomers, Iso1 – Iso4, were identified by the density-functional theory. Our results indicate the most stable structure Iso2 adopts the C 2 v Au 50 core with Marks-decahedral (m-Dh) Au 18 inner core. The calculated HOMO–LUMO gap is 0.74 eV, which is very close to that of Au 67 (SR) 35 2– . Further analysis suggests the 14 kDa RS-AuNPs might be not only the turn point between the fused core structure and the compact core structure but also the turn point between the one-shell inner core structure and the multishell inner core structure. The threshold number of Au atoms in bulk-like RS-AuNPs is evaluated as ∼263 based on the linear fitting of the HOMO–LUMO gaps of various RS-AuNPs including Au 68 (SR) 34 . The research on the medium-sized Au 68 (SR) 34 establishes a bridge between smaller and larger RS-AuNPs, which is beneficial for us to better understand the structures of the RS-AuNPs.