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

Abstract

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 2v 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.

Correlating the Structure and Optical Absorption Properties of Au76(SR)44 Cluster

“…From Figure 4, the energy computations indicated the new structure model is more stable by 5.26−7.97 eV than that constructed from Au 49 , Au 52 , and Au 56 cores. Because of the close atomic compositions of Au 76 (SR) 44 and the recently reported nearly spherical Au 67 (SR) 35 2− and Au 68 (SR) 32 clusters, we have constructed a series of isomers containing spherical Au cores as well in order to give a rigorous confirmation of the relative stabilities of the proposed structure model. These spherical isomer structures are constructed from a Au 55 core with either icosahedral, decahedral, or octahedral configuration.…”

“…According to this concept, 31,32 any Au n (SR) m nanoclusters can be divided into a symmetric gold core covered by interfacial staple motifs (i.e., −SR[AuSR] x −, x = 1, 2, 3, ...). Over the past few years, the "divide-and-protect" concept combined with density functional theory (DFT) computations has led to predictions of a number of cluster structures, including Au 187 (SR) 68 , 33 Au 144 (SR) 60 , 34 Au 68 (SR) 34 , 35 Au 67 (SR) 35 2− , 36 Au 44 (SR) 28 , 37 Au 40 (SR) 24 , 38 Au 38 (SR) 24 , 39,40 Au 25 (SR) 18 − , 41 Au 24 (SR) 20 , 42 Au 20 (SR) 16 , 43 Au 18 (SR) 14 , 44 Au 15 (SR) 13 , 45,46 and Au 12 (SR) 9 + . 47 Although tremendous research efforts have been made on the characterization of atomic structures, an important issue about the structural evolution of Au n (SR) m clusters in the size range 1−2 nm remained elusive.…”

Unraveling a generic growth pattern in structure evolution of thiolate-protected gold nanoclusters

“…Since the first successful crystallization of the thiolateprotected gold nanocluster Au 102 (SR) 44 in 2007, 1 research into the structural evolution and structure-property relationship of thiolate-protected gold nanoclusters has attracted considerable attention due to high potential of these nanoclusters for applications in electronics, catalysis and bioengineering. [2][3][4][5][6][7] Significant advancement in structure determination has been made on the basis of X-ray crystallography, 1,8-20 single-particle transmission electron microscopy (SP-TEM), 21 as well as densityfunctional theory (DFT) computation [22][23][24][25][26][27][28][29][30] in conjunction with the "divide and protect" formulation. 4,31 Although the latter formulation can be very useful in seeking optimal ligand patterns for given gold-core structures, generic growth patterns of the gold nanoclusters are still largely unknown, which hinders the development of large-sized ligand-protected gold nanoclusters for optical and electronic applications.…”

A grand unified model for liganded gold clusters

“…Nevertheless, these revelations appear serendipitous as the structural determination largely hinges on availability of single crystals for the liganded gold clusters. Although density-functional theory computation has been widely applied to predict the structures of many gold clusters646566676869707172737475767778, ultimate confirmation still requires X-ray crystallography measurements. Theoretical efforts have also been made in the past for more general unification models to comprehend stabilities of liganded gold clusters with apparently very different and seemingly unrelated complex structures.…”