Catalyzed assembly of hollow silver-sulfide cluster through self-releasable anion template

Enhancement of Photoluminescence Quantum Yield of Silver Clusters by Heavy Atom Effect

Many ligand-protected metal clusters exhibit phosphorescence at room temperature. However, strategies for improving their phosphorescence quantum yield, a critical parameter of performance, remain poorly developed. In contrast, fluorescent dyes are commonly modified by introducing heavy atoms, such as iodine (I), to enhance intersystem crossing in the excited state, thereby harnessing the heavy atom effect to increase phosphorescence efficiency. In this study, a pair of ligand-protected silver (Ag) clusters is successfully synthesized with internal cavities encapsulating anions (Xz -), namely sulfide ions (S2-) or iodide ions (I-), which significantly differ in atomic number each other. Single-crystal X-ray diffraction and nuclear magnetic resonance spectroscopy revealed that the resulting Ag clusters are composed of X@Ag54S20(thiolate)20(sulfonate)m, where (X, m) = (S, 12) or (I, 11). X-ray photoelectron spectroscopy revealed that the Ag atoms in these compounds exhibit a mixed-valence state. Furthermore, experiments on their photoluminescence revealed that a heavy central anion induced an internal heavy-atom effect similar to that observed in organic fluorescent dyes. As a result, the phosphorescence quantum yield became 16 times higher when S2- is replaced by I- as the central atom.

Isolation of mixed valence charge-neutral Ag12, and dicationic Ag10 nano-clusters stabilized by carbene-phosphaalkenides

Cyclic alkyl(amino) carbene (cAAC)-supported phosphaalkenides (cAACP)- have been employed as ligands for the isolation of two atomically precise mixed valence paramagnetic AgI/012Cl3, and AgI/010, nano-clusters [(Me2-cAACP)6Ag12Cl3] (2), and [(Me2-cAACP)6Ag10](NTf2)2 (4). 2 and 4 have been structurally characterized by single-crystal X-ray diffraction revealing the presence of three Ag0 atoms, nine AgI ions (2); and two Ag0 atoms, eight AgI ions (4), respectively. The clustering inorganic unit Ag12Cl3 in 2 has been found to be surrounded by six mono-anionic μ3-cAACP moieties having 3-bar symmetry. 2 and 4 have been studied by cyclic voltammetry, UV-vis, ESI-MS, XPS, EPR spectroscopy, and DFT calculations.

Synthesis of Two Neutral Silver Alkynyl Nanoclusters by a Single Divalent Tetrahedral Anion Template and a Study of Their Optical Features

The synthesis of nanoclusters from simple structural units is usually a challenging process because of the complexity and unpredictability of the self-assembly process of these types of compounds. Herein, two new neutral 19-nuclearity silver nanoclusters based on alkynyl ligands with the formulas [(CrO₄)@Ag₁₉(C≡C^tBu)₈(Ph₂PO₂)₆(tfa)₃(CH₃OH)₂] (1) and [(SO₄)@Ag₁₉(C≡C^tBu)₈(Ph₂PO₂)₆(tfa)₃(CH₃OH)₂] (2), in which tfa = trifluoroacetate, were synthesized, and their structures were investigated by single-crystal and powder X-ray diffraction, electrospray ionization mass spectrometry, elemental analyses, and Fourier transform infrared spectroscopy. The surface ligands of Ph₂PO₂H and trifluoroacetate were assembled through hydrogen bonding, metal-aromatic interactions, and coordination bonding around 19 silver atoms as the metal skeletons of the nanoclusters. Sulfate and chromate anions, as a template within the metal skeleton of clusters through bonding with silver atoms, stabilized the structure. In addition, the UV-vis absorption spectroscopy, luminescence properties, and thermal stability of the nanoclusters were investigated.

A comparative study of [Ag11(iPrS)9(dppb)3]2+ and [Ag15S(sBuS)12(dppb)3]+: templating effect on structure and photoluminescence

Atomically precise silver clusters with tunable photoluminescence (PL) properties have attracted extensive attention due to their great value for basic science and future applications. Here, we report that the addition of a sulfido template into a triangular thiolated silver cluster [Ag11(iPrS)9(dppb)3]·2CF3SO3·CH3OH (Ag11, dppb = 1,4-bis(diphenylphosphino)butane), which is emissive at 660 nm under ambient conditions, produced another silver cluster [S@Ag15(sBuS)12(dppb)3]·CF3SO3·H2O (Ag15) that displays 716 nm emission with a 56 nm redshift aided by the ligand sec-butyl mercaptan. The sulfido template, which affects the geometrical and electronic structures, results in a redshift of Ag11 room-temperature PL as a result of opening up the template-to-metal charge transfer (TMCT) and disturbing the electronic transition between the metal core and ligands at the periphery.

A construction guide for high-nuclearity (≥50 metal atoms) coinage metal clusters at the nanoscale: bridging molecular precise constructs with the bulk material phase

Synthesis remains a major strength in chemistry and materials science and relies on the formation of new molecules and diverse forms of matter. The construction and identification of large molecules poses specific challenges and has historically lain in the realm of biological (organic)-type molecules with evolved synthesis methods to support such endeavours. But with the development of analytical tools such as X-ray crystallography, new synthesis methods toward large metal-based (inorganic) molecules and clusters have come to the fore, making it possible to accurately determine the precise distribution of hundreds of atoms in large clusters. In this review, we focus on different synthesis protocols used to form new metal clusters such as templating, alloying and size-focusing strategies. A specific focus is on group 11 metals (Cu, Ag, Au) as they currently predominate large metal cluster investigations and related Au and Ag bulk surface phenomena. This review focuses on metal clusters that have very high-nuclearity, i.e. with 50 or more metal centers within the isolated cluster. This size domain, it is believed, will become increasingly important for a variety of applications as these metal clusters are positioned at the interface between the molecular and bulk phases, whilst remaining a classic nanomaterial and retaining unique nano-sized properties.

Monitoring the growth of Ag–S clusters through crystallization of intermediate clusters

We report a series of Ag–S nanoscale clusters in an attempt to understand the growth process of Ag₂S clusters.