Control efficacy of complex networks

Acknowledgements W.-X.W. was supported by CNNSF under Grant No. 61573064, and No. 61074116 the Fundamental Research Funds for the Central Universities and Beijing Nova Programme, China. Y.-C.L. was supported by ARO under Grant W911NF-14-1-0504.Peer reviewedPublisher PD

Unraveling structures of protection ligands on gold nanoparticle Au\u3csub\u3e68\u3c/sub\u3e(SH)\u3csub\u3e32\u3c/sub\u3e

New low-energy atomic structures of the thiolate-protected gold nanoparticle Au68(SH)32 are uncovered, where the atomic positions of the Au atoms are taken from the recent single-particle transmission electron microscopy measurement by Kornberg and co-workers, whereas the pattern of thiolate ligands on the gold core is attained on the basis of the generic formulation (or rule) of the “divide and protect” concept. Four distinct low-energy isomers, Iso1 to Iso4, whose structures all satisfy the generic formulation, are predicted. Density-functional theory optimization indicates that the four isomers are all lower in energy by 3 to 4 eV than the state-of-the-art low-energy isomer reported. Further analysis of the optimized structures of Au68(SH)32 shows that the structure of gold core in Iso1 to Iso4 is consistent with the experiment, whereas the positions of a few Au atoms at the surface of gold core are different. The computed optical absorption spectra of the four isomers are consistent with the measured spectrum. Computation of catalytic properties of Au68(SH)32 toward CO oxidation suggests that the magic number cluster can be a stand-alone nanoscale catalyst for future catalytic applications

Reply to ‘On the bonding in ligand-protected gold clusters’

In the recent Correspondence, Professor Henrik Grönbeck made several comments on the recently developed grand unified model (GUM), in particular using the ligand-protected gold cluster [Au25(SR)18]1− as an example. We noted that the latter cluster can be viewed as belonging to a special group of ligand-protected gold clusters that contain one or several icosahedral Au13 motifs. For this group of clusters, a secondary block Au13(8e) has been identified as a more convenient way to describe their structure anatomy and evolution. Another extension of the GUM is the identification of the new elementary block, Au3(μ3-S), with zero valence electron [referred as Au3(μ3-S)(0e)] to describe all crystallized ligand-protected gold clusters containing μ3-S motifs. In this correspondence, first, we discuss the purpose of GUM development in more detail. Next, we briefly discuss the secondary block Au13(8e) and show new computational results on the stabilities of Au3(2e) and Au4(2e) elementary blocks. Then two Au62+ clusters are used as the simplest example (a suggestion credited to a reviewer of ref. 2) to better explain the GUM and high stability of Au3(2e), followed by a summary and perspective

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

Precise control of the growth of thiolate-protected gold nanoclusters is a prerequisite for their applications in catalysis and bioengineering. Here, we bring to bear a new series of thiolateprotected nanoclusters with a unique growth pattern, i.e., Au20(SR)16, Au28(SR)20, Au36(SR)24, Au44(SR)28, and Au52(SR)32. These nanoclusters can be viewed as resulting from the stepwise addition of a common structural motif [Au8(SR)4]. The highly negative values of the nucleus-independent chemical shift (NICS) in the center of the tetrahedral Au4 units suggest that the overall stabilities of these clusters stem from the local stability of each tetrahedral Au4 unit. Generalization of this growth-pattern rule to large-sized nanoclusters allows us to identify the structures of three new thiolateprotected nanoclusters, namely, Au60(SR)36, Au68(SR)40, and Au76(SR)44. Remarkably, all three large-sized nanoclusters possess relatively large HOMO–LUMO gaps and negative NICS values, suggesting their high chemical stability. Further extension of the growth-pattern rule to the infinitely long nanowire limit results in a one-dimensional (1D) thiolate-protected gold nanowire (RS-AuNW) with a band gap of 0.78 eV. Such a unique growth-pattern rule offers a guide for precise synthesis of a new class of large-sized thiolate-protected gold nanoclusters or even RS-AuNW which, to our knowledge, has not been reported in the literature

Medium-sized Au\u3csub\u3e40\u3c/sub\u3e(SR)\u3csub\u3e24\u3c/sub\u3e and Au\u3csub\u3e52\u3c/sub\u3e(SR)\u3csub\u3e32\u3c/sub\u3e nanoclusters with distinct gold-kernel structures and spectroscopic features

We have analyzed the structures of two medium-sized thiolateprotected gold nanoparticles (RS-AuNPs) Au40(SR)24 and Au52(SR)32 and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au40(SR)24 and Au52(SR)32 nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-AuNPs of two other prevailing Au-kernels identified from previous experiments, namely the Ino-decahedral kernel and icosahedral kernel. The distinct X-ray diffraction patterns of RS-AuNPs with the three different types of Au-kernels can be utilized as signature features for future studies of structures of RS-AuNPs. Moreover, the simulated UV/Vis absorption spectra and Kohn–Sham orbital energy-level diagrams are obtained for the Au40(SR)24 and Au52(SR)32, on the basis of time-dependent density functional theory computation. The extrapolated optical bandedges of Au40(SR)24 and Au52(SR)32 are 1.1 eV and 1.25 eV, respectively. The feature peaks in the UV/Vis absorption spectra of the two clusters can be attributed to the d → sp electronic transition. Lastly, the catalytic activities of the Au40(SR)24 and Au52(SR)32 are examined using CO oxidation as a probe. Both medium-sized thiolate-protected gold clusters can serve as effective stand-alone nanocatalysts