Atomically precise nanoclusters (NCs) are of great interest due to their well-defined structures and molecule-like properties. Understanding their structure-property relationship is an important task because it can help tailor their structures to achieve specific desired properties. In this study, the temperature-dependent bonding properties of Ag44(SR)30 have been revealed by the extended X-ray absorption fine structure (EXAFS) with a new structure analysis method, which includes two Ag-S and two Ag-Ag fitting shells. It has been proven that the EXAFS fitting quality can be improved significantly compared with the conventional method. New insights into Ag-S bondings were discovered based on the fitting results obtained from the new method. It allows us to observe two different bonding properties within the Ag-S motifs, which cannot be discovered by using the conventional method. Additionally, the metal core of Ag44(SR)30 exhibits uncommon thermal behavior, which could be connected to the absence of the center atom in the icosahedral core. Our results demonstrate that the new structure analysis method can provide a more reliable comparison of NCs structural changes than the conventional method and it could be applicable to other NCs. The revealed temperature-dependent bonding properties can provide insights into the structure-property relationship of Ag44(SR)30, which can help design new NCs materials with tailored properties.

We report the mechanism on the ultrahigh stability of Na4Ag44(SR)30by uncovering how coordinating solvents interact with the Na4Ag44(SR)30nanocluster at the atomic scale. Through synchrotron X-ray experiments and theoreticalcalculations, it was found that strongly coordinating aprotic solvents interactwith surface Ag atoms, particularly between ligand bundles, which compressesthe Ag core and relaxes surface metal-ligand interactions. Furthermore, waterwas used as a cosolvent to demonstrate that semi-aqueous conditions play animportant role in protecting exposed surface regions and can further influencethe local structure of the silver nanocluster itself. Notably, undersemi-aqueous conditions, aprotic coordinating solvent molecules preferentiallyremain on the metal surface while water molecules interact with ligands, andligand bundling persisted across the varied solvation conditions.

Metal heteroatom substitution in molecular nanoparticles offers a unique opportunity to study alloying with an unprecedented level of detail and control, which may be important for applications in optics, electronics, medicine, and catalysis. Many examples of single- or few-heteroatom substitutions exist in molecular nanoparticles, but true alloys with compositions varying over a wide range of substitutions are rare. Here, we study M4AuxAg44-x (p-MBA)(30) alloy nanoparticles as a model system, where M is a countercation and p-MBA is a p-mercaptobenzoic acid ligand, and where 0 <= x <= 12 represents the full range of possible compositions, all of which are stable in solution. Synthetic reactions produced M4AuxAg44-x(p-MBA)(30) alloy nanoparticle products whose compositions were found to be a complex function of the reaction mixture composition. Postsynthetic reactions showed that oxidation of M4AuxAg44-x(p-MBA)(30) nanoparticles was slowed in a monotonic fashion by the addition of gold atoms. Density functional theory provided insights into the variation in the chemistry, electronic structure, and reactivity of M4AuxAg(44-x)(P-MBA)(30) nanoparticle alloys as a function of composition and showed that the stabilization mechanism was the result of the electrophilicity of the gold atoms, which polarized the metal core. An oxidation reaction mechanism was proposed based on these experimental and computational results, which involved the octahedrally located silver atoms.

Crystals of M 4 Au 12 Ag 32 ( p -MBA) 30 bimetallic monolayer-protected clusters (MPCs), where p -MBA is p -mercaptobenzoic acid and M + is a counter-cation ( M = Na, Cs) have been grown and their structure determined. The molecular structure of triacontakis[(4-carboxylatophenyl)sulfanido]dodecagolddotriacontasilver, Au 12 Ag 32 (C 7 H 5 O 2 S) 30 or C 210 H 150 Ag 32 Au 12 O 60 S 30 , exhibits point group symmetry 3 at 100 K. The overall diameter of the MPC is approximately 28 Å, while the diameter of the Au 12 Ag 20 metallic core is 9 Å. The structure displays ligand bundling and intermolecular hydrogen bonding, which gives rise to a framework structure with 52% solvent-filled void space. The positions of the M + cations and the DMF solvent molecules within the void space of the crystal could not be determined. Three out of the five crystallographically independent ligands in the asymmetric unit cell are disordered over two sets of sites. Comparisons are made to the all-silver M 4 Ag 44 ( p -MBA) 30 MPCs and to expectations based on density functional theory.

Nanoparticles rival pharmaceuticals in synthetic inefficiency, in particular as measured by process mass intensity, with by far the largest contribution to waste being from solvents. We have therefore developed a greener method of synthesizing silver nanoparticles using a paste format instead of a metal salt solution. The paste-based synthesis requires 87% less solvent yet still produces exclusively Na4Ag44(p-MBA)30 nanoparticles, without size sorting, with 89% yield. By using a stoichiometric silver-thiolate polymer as a precursor to intimately mix the metal atoms and ligands, and by using a small amount of liquid to form a paste to promote mass transport, the heterogeneity and kinetics problems that are associated with entirely solid-state syntheses were avoided. Because the nanoparticle product was also a paste, solvent use for postprocessing was minimized. Use of the silver-thiolate polymer can also reduce health risks associated with hazardous free thiols in conventional solution-phase syntheses. Usi...

Fathoming the principles underpinning the structures of monolayer-coated molecular metal nanoparticles remains an enduring challenge. Notwithstanding recent x-ray determinations, coveted veritable de novo structural predictions are scarce. Building on recent syntheses and de novo structure predictions of M3Au x Ag17-x (TBBT)12, where M is a countercation, x = 0 or 1, and TBBT is 4-tert-butylbenzenethiol, we report an x-ray-determined structure that authenticates an a priori prediction and, in conjunction with first-principles theoretical analysis, lends force to the underlying forecasting methodology. The predicted and verified Ag(SR)3 monomer, together with the recently discovered Ag2(SR)5 dimer and Ag3(SR)6 trimer, establishes a family of unique mount motifs for silver thiolate nanoparticles, expanding knowledge beyond the earlier-known Au-S staples in thiol-capped gold nanoclusters. These findings demonstrate key principles underlying ligand-shell anchoring to the metal core, as well as unique T-like benzene dimer and cyclic benzene trimer ligand bundling configurations, opening vistas for rational design of metal and alloy nanoparticles.

M4Ag44(p-MBA)30 molecular nanoparticles, where M is an alkali metal, have recently been shown to have exceptional stability, which confers unique traits to this molecule. In particular, the synthesis is straightforward, produces a truly single-sized molecular product, and has a quantitative yield. Here we describe in detail the results of experimental and theoretical studies on the synthesis, structure, stability, and electronic and optical properties of M4Ag44(p-MBA)30, including ESI-MS, NMR, optical absorption, IR, TGA, and other measurements as well as DFT and TDDFT calculations. This work deepens our understanding of this important Ag molecule, which should facilitate its use in a wide range of fundamental studies and applications.

M4Ag44(p-MBA)30 molecular nanoparticles, where M is an alkali metal, have recently been shown to have exceptional stability, which confers unique traits to this molecule. In particular, the synthesis is straightforward, produces a truly single-sized molecular product, and has a quantitative yield. Here we describe in detail the results of experimental and theoretical studies on the synthesis, structure, stability, and electronic and optical properties of M4Ag44(p-MBA)30, including ESI-MS, NMR, optical absorption, IR, TGA, and other measurements as well as DFT and TDDFT calculations. This work deepens our understanding of this important Ag molecule, which should facilitate its use in a wide range of fundamental studies and applications.

Self-assembled nanoparticle superlattices, which consist of inorganic cores capped by organic ligands, can show emergent behaviour as a result of the coupling between their nanoscale components. The atom-level structure of a silver nanoparticle superlattice, deduced from X-ray imaging and simulations, is now reported as well as its response to hydrostatic compression, which involves anomalous pressure softening and correlated chiral rotation of the nanoparticles.

Silver nanoparticles are susceptible to oxidation and have accordingly received less attention than gold nanoparticles; ultrastable silver nanoparticles are now reported, which can be produced in very large quantities as a single-sized molecular product, and the origins of their enhanced stability are elucidated using a single-crystal X-ray structure and first-principles calculations.