Search results for "superatom"
showing 10 items of 39 documents
Ag44(SeR)30: A Hollow Cage Silver Cluster with Selenolate Protection.
2015
Selenolate protected, stable and atomically precise, hollow silver cluster was synthesized using solid state as well as solution state routes. The optical absorption spectrum shows multiple and sharp features similar to the thiolated Ag44 cluster, Ag44(SR)30 whose experimental structure was reported recently. High-resolution electrospray ionization mass spectrometry (HRESI MS) shows well-defined molecular ion features with two, three, and four ions with isotopic resolution, due to Ag44(SePh) 30. Additional characterization with diverse tools confirmed the composition. The closed-shell 18 electron superatom electronic structure, analogous to Ag44(SR)30 stabilizes the dodecahedral cage with a…
Ligand-Protected Gold Nanoclusters as Superatoms—Insights from Theory and Computations
2012
Abstract Gold clusters and nanoparticles, stabilized by various ligands, exhibit a rich array of interesting and important electronic, optical, chemical and catalytic properties. Many particles can now be synthesized by wet chemistry, and they can be handled as normal chemicals: stored, modified and functionalized for applications in medical therapy, biolabelling, sensing, nanoelectronics and catalysis. In recent years, understanding of the stability, surface chemistry and functionalization of these interesting building blocks of nano-matter has taken a quantum leap. This is facilitated by simultaneous breakthroughs in experimental and theoretical fronts concerning accurate structural deter…
Cd12Ag32(SePh)36: Non-Noble Metal Doped Silver Nanoclusters
2019
While there are numerous recent reports on doping of a ligand-protected noble metal nanocluster (e.g., Au and Ag) with another noble metal, non-noble metal (e.g., Cd) doping remains challenging. Here, we design a phosphine-assisted synthetic strategy and synthesize a Cd doped Ag nanocluster, Cd12Ag32(SePh)36 (SePh: selenophenolate), which exhibits characteristic UV–vis absorption features and rare near-infrared (NIR) photoluminescence at ∼1020 nm. The X-ray single crystal structure reveals an asymmetric two-shell Ag4@Ag24 metal kernel protected by four nonplanar Cd3Ag(SePh)9 metal–ligand frameworks. Furthermore, the electronic structure analysis shows that the cluster is a 20-electron “supe…
Electronic structure of Gold, Aluminum and Gallium Superatom Complexes
2011
Using ab initio computational techniques on crystal determined clusters, we report on the similarities and differences of Al${}_{50}$(C${}_{5}$(CH${}_{3}{{)}_{5})}_{12}$, Ga${}_{23}$(N(Si(CH${}_{3}{)}_{3}$)${}_{2}$)${}_{11}$, and Au${}_{102}$(SC${}_{7}$O${}_{2}$H${}_{5}$)${}_{44}$ ligand-protected clusters. Each of the ligand-protected clusters in this study shows a similar stable character which can be described via an electronic shell model. We show here that the same type of analysis leads consistently to derivation of a superatomic electronic counting rule, independently of the metal and ligand compositions. One can define the cluster core as the set of atoms where delocalized single-an…
Atomic and electronic structure of gold clusters: understanding flakes, cages and superatoms from simple concepts.
2008
Atomic structure and electronic structure are intimately interrelated properties of nanoclusters and nanoparticles, defining their stability, electronic, optical and chemical properties, in other words, their usability as potential components for nanoscale devices. This tutorial review attempts to describe the development in understanding the structures of bare and ligand-protected gold clusters over the past decade, based on selected density-functional-theory calculations. This review should be of interest both to newcomers in the field and to an interdisciplinary community of researchers working in synthesis, characterization and utilization of ligand-protected gold clusters.
A unified view of ligand-protected gold clusters as superatom complexes
2008
Synthesis, characterization, and functionalization of self-assembled, ligand-stabilized gold nanoparticles are long-standing issues in the chemistry of nanomaterials. Factors driving the thermodynamic stability of well documented discrete sizes are largely unknown. Herein, we provide a unified view of principles that underlie the stability of particles protected by thiolate (SR) or phosphine and halide (PR 3 , X) ligands. The picture has emerged from analysis of large-scale density functional theory calculations of structurally characterized compounds, namely Au 102 (SR) 44 , Au 39 (PR 3 ) 14 X 6 − , Au 11 (PR 3 ) 7 X 3 , and Au 13 (PR 3 ) 10 X 2 3+ , where X is either a halogen or a thiol…
Ag44(EBT)26(TPP)4Nanoclusters With Tailored Molecular and Electronic Structure
2021
Although atomically precise metalloid nanoclusters (NCs) of identical size with distinctly different molecular structures are highly desirable to understand the structural effects on the optical and photophysical properties, their synthesis remains highly challenging. Herein, we employed phosphine and thiol capping ligands featuring appropriate steric effects and synthesized a charge-neutral Ag NC with the formula Ag44 (EBT)26 (TPP)4 (EBT: 2-ethylbenzenethiolate; TPP: triphenylphosphine). The single-crystal X-ray structure reveals that this NC has a hollow metal core of Ag12 @Ag20 and a metal-ligand shell of Ag12 (EBT)26 (TPP)4 . The presence of mixed ligands and long V-shaped metal-ligand …
Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl-Protected Body-Centered Cubic Clus…
2016
The synthesis, structure, substitution chemistry, and optical properties of the gold-centered cubic monocationic cluster [Au@Ag8@Au6(C≡CtBu)12]+ are reported. The metal framework of this cluster can be described as a fragment of a body-centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [MnAg8−nAu7(C≡CtBu)12]+ clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [CunAg8Au7−n(C≡CtBu)12]+ clusters (n=1–6), with the Cu atom(s) presumably occup…
A Homoleptic Alkynyl‐Ligated [Au13Ag16L24]3‐ Cluster as a Catalytically Active Eight‐Electron Superatom
2021
A brand new alkynylated cluster [Au 13 Ag 16 (C 10 H 6 NO) 24 ] 3- is prepared by NaBH 4 mediated reduction method. The AuAg clusters are confirmed by various sophisticated characterization techniques. It manifested the unique metal framework of “Au center @Ag 12 @Au 12 Ag 4 ” is protected by 24 atypical alkyne ligands L (L = C 10 H 6 NO). The ligands were found to construct a unique type of motif L-(Ag)-Au-(Ag)-L at the cluster interface, where, the alkyne (C≡C) group of each L was linked by sharing an Au atom through the σ bonds and each C≡C group was discretely connected to chemically different Ag atom (Ag icosahedral /Ag cap ) through π bonds. The electronic and optical properties of [A…
Robust, Highly Luminescent Au13 Superatoms Protected by N-Heterocyclic Carbenes
2019
Gold superatom nanoclusters stabilized entirely by N-heterocyclic carbenes (NHCs) are reported. The reduction of well-defined NHC–Au–Cl complexes produces clusters com-prised of an icosahedral Au13 core surrounded by a symmetrical arrangement of 9 NHCs and 3 chlorides. X-ray crystallography shows that the clusters are characterized by multiple CH–π and π–π interactions, which rigidify the ligand and likely con-tribute to the exceptionally high photoluminescent quantum yields observed, up to 16.0 %, which is significantly greater than the most luminescent ligand-protected Au13 superatom cluster. Density functional theory analysis suggests that clus-ters are 8-electron superatoms with a wide …