Au₂₅(SR)₁₈: the captain of the great nanocluster ship

Abstract

Noble metal nanoclusters are in the intermediate state between discrete atoms and plasmonic nanoparticles and are of significance due to their atomically accurate structures, intriguing properties, and great potential for applications in various fields. In addition, the size-dependent properties of nanoclusters construct a platform for thoroughly researching the structure (composition)-property correlations, which is favorable for obtaining novel nanomaterials with enhanced physicochemical properties. Thus far, more than 100 species of nanoclusters (mono-metallic Au or Ag nanoclusters, and bi- or tri-metallic alloy nanoclusters) with crystal structures have been reported. Among these nanoclusters, Au25(SR)18-the brightest molecular star in the nanocluster field-is capable of revealing the past developments and prospecting the future of the nanoclusters. Since being successfully synthesized (in 1998, with a 20-year history) and structurally determined (in 2008, with a 10-year history), Au25(SR)18 has stimulated the interest of chemists as well as material scientists, due to the early discovery, easy preparation, high stability, and easy functionalization and application of this molecular star. In this review, the preparation methods, crystal structures, physicochemical properties, and practical applications of Au25(SR)18 are summarized. The properties of Au25(SR)18 range from optics and chirality to magnetism and electrochemistry, and the property-oriented applications include catalysis, chemical imaging, sensing, biological labeling, biomedicine and beyond. Furthermore, the research progress on the Ag-based M25(SR)18 counterpart (i.e., Ag25(SR)18) is included in this review due to its homologous composition, construction and optical absorption to its gold-counterpart Au25(SR)18. Moreover, the alloying methods, metal-exchange sites and property alternations based on the templated Au25(SR)18 are highlighted. Finally, some perspectives and challenges for the future research of the Au25(SR)18 nanocluster are proposed (also holding true for all members in the nanocluster field). This review is directed toward the broader scientific community interested in the metal nanocluster field, and hopefully opens up new horizons for scientists studying nanomaterials. This review is based on the publications available up to March 2018.

Same Magic Number but Different Arrangement: Alkynyl‐Protected Au25 with D3 Symmetry

“…We also managed to achieve total structure determination of alkynyl‐protected Au 144 , which gave important information on the elusive structure of Au 144 (SR) 60 . These findings raises a question whether there exists Au 25 protected by alkynyl ligands as the counterpart of the most extensively studied gold nanocluster [Au 25 (SR) 18 ] − …”

Understanding and designing one-dimensional assemblies of ligand-protected metal nanoclusters

“…S1(a), ESI †) used by Maran et al 37,38 for the formation of 1D-CS has surfaces that are crowded with ligands. 41 Therefore, even if the ligand structure is varied, there is almost no change in the distribution of the ligands. Meanwhile, although it was not mentioned in the original paper, [Au 4 Pd 2 (SC 2 H 4 Ph) 8 ] 0 also formed 1D-CS in a single crystal ( Fig.…”

Elucidating ligand effects in thiolate-protected metal clusters using Au24Pt(TBBT)18 as a model cluster

“…Among them, thiolate-protected gold clusters (Au n (SR) m ) have a high stability in the solution and solid state, and exhibit multiple physical/chemical properties and functions that are suitable for application including photoluminescence, redox behavior, and catalysis. 27 For these reasons, Au n (SR) m clusters have been the subject of increasing research in recent years. 5 In the study of Au n (SR) m clusters, when 2-phenylethanethiolate (PET; Scheme S1(a) †) or 4-tert-butylbenzenethiolate (TBBT; Scheme S1(b) †) is used as a ligand, the single crystallization of clusters is relatively easy and the determination of the geometrical structure of Au n (SR) m clusters is possible by singlecrystal X-ray diffraction analysis (SCXRD).…”