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An alkynyl-protected gold nanocluster [Au24(CCPh)14(PPh3)4](SbF6)2 has been prepared by a direct reduction method. Single-crystal X-ray diffraction reveals that the molecular structure contains a Au22 core that is made of two Au13-centered cuboctahedra that share a square face. Two staple-like PhCCAuCCPh motifs are located around the center of the rod-like Au22 core. This Au24 nanocluster is highly emissive in the near-infrared region with λmax=925 nm and the nature of the HOMO-LUMO transition is investigated by time-dependent DFT calculations. [ABSTRACT FROM AUTHOR]

The exact interaction between Au cores and surface ligands remains largely unknown because of the complexity of the structure and chemistry of ligand/Au-core interfaces in ligand-protected Au nanoclusters (AuNCs), which are commonly found in many organic–inorganic complexes. Here, femtosecond transient absorption measurement of the excited-state dynamics of a newly synthesized phosphine-protected cluster [Au20(PPhpy2)10Cl4]Cl2 (1) is reported. Intramolecular charge transfer (ICT) from the Au core to the peripheral ligands was identified. Furthermore, we found that solvation strongly affected ICT at ligand/Au-core interfaces while by choosing several typical alcoholic solvents with different intrinsic solvation times, we successfully observed that excited-state relaxation dynamics together with displacive excited coherent oscillation of Au20 clusters were significantly modulated through the competition between solvation and surface trapping. The results provide a fundamental understanding of the structure–property relationships of the solvation-dependent core–shell interaction of AuNCs for the potential applications in catalysis, sensing and nanoelectronics. [ABSTRACT FROM AUTHOR]

The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster [Au20(PP3)4]Cl4 (PP3=tris(2-(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)-tetraphosphine precursor in dichloromethane solution. Single-crystal structural determination reveals that the cluster molecular structure has C3 symmetry. It consists of a Au20 core consolidated by four peripheral tetraphosphines. The Au20 core can be viewed as the combination of an icosahedral Au13 and a helical Y-shaped Au7 motif. The identity of this Au20 cluster is confirmed by ESI-MS. The chelation of multidentate phosphines enhances the stability of this Au20 cluster. [ABSTRACT FROM AUTHOR]

A novel Pt(II) terpyridine complex that has a nicotinamide moiety linked to the terpyridyl ligand has been synthesized in good yield and studied structurally and spectroscopically. The complex, [Pt(Nttpy)-Cl](PF6)2 where Nttpy = 4'-(p-nicotinamide-N-methylphenyl)-2,2':6',2''-terpyridine, is observed to be brightly luminescent in the solid state at room temperature and at 77 K. The complex exhibits reversible vapochromic behavior and crystallographic change in the presence of several volatile organic solvents. Upon exposure to methanol vapors, the complex changes color from red to orange, and a shift to higher energy is observed in the emission maximum with an increase in excited-state lifetime and emission intensity. The crystal and molecular structures of the orange and red forms, determined by single-crystal X-ray diffraction on the same single crystal, were found to be equivalent in the molecular sense and only modestly different in terms of packing. In both forms, the cationic Pt(II) complexes possess distorted square planar geometries. Analysis of the orange form's crystal packing reveals the presence of solvent molecules in lattice voids, Pt…Pt separations averaging 3.75 Å and a zigzag arrangement between nearest neighbor Pt atoms, whereas the red form is devoid of solvent within the crystal lattice and contains complexes stacked with a nearly linear arrangement of Pt(II) ions having an average distance of 3.33 Å. On the basis of the crystallographic data, it is evident that sorption of methanol vapor induces a change in intermolecular contacts and Pt…Pt interactions in going from red to orange. Disruption of the d8-d8 metallophilic interactions consequently alters the emitting state from ³[(d)σ*--π*(terpyridine)] that is formally a metal--metal-to-ligand charge transfer (MMLCT) state in the red form to one in which the HOMO corresponds to a more localized Pt(d) orbital in the red form (³MLCT). [ABSTRACT FROM AUTHOR]

New double salts Ag2C2·6AgO2CCHF2 (1), [HPyCH2OH][Ag9(C2)(CF3CO2)9(HPyCH2OH)(H2O)]·0.5H2O (PyCH2OH=4-(hydroxymethyl)pyridine) (2), Ag2C2·5CF3SO3Ag·2MeCN·2H2O (3) and Ag2C2·8CF3SO3Ag·2EtCN·3H2O (4) have been synthesized by dissolving Ag2C2 in an aqueous solution of the corresponding silver salt followed by the addition of an ancillary ligand. Complex 1 has a three-dimensional structure in which unprecedented basket-like silver cages are inter-connected by difluoroacetate ligands. In 2, centrosymmetric (C2)2@Ag14 double cages with each half taking the shape of a triangulated dodecahedron are linked through additional silver atoms to generate an infinite chain, and unsupported silver(I)–silver(I) interactions exist between neighboring chains. Of the two independent 4-(hydroxymethyl)pyridinium ions in 2, one acts in the O-ligating mode, which is observed for the first time, while the other merely serves to provide charge balance and space-filling. Both 3 and 4 are layer-type structures in which the basic building unit is a distorted monocapped octahedron and monocapped trigonal prism, respectively. [Copyright &y& Elsevier]

The reactions of Ag2C2 and the corresponding silver perfluoro-dicarboxylates result in the formation of three new double and triple salts, Ag2C2·3AgO2CCF2CF2CO2Ag·7H2O ( 1), 2Ag2C2·6AgO2CCF2CF2CO2Ag·AgNO3·12H2O ( 2) and Ag2C2·4AgO2CCF2CF2CF2CO2Ag·17.5H2O ( 3), which have been structurally characterized by single crystal X-ray analysis. Their structures contain silver cages of various shapes: crown in 1, pentagonal bipyramid together with monocapped pentagonal bipyramid in 2, and square antiprism in 3, each containing an encapsulated acetylide dianion. Except for the pentagonal bipyramid, the other three silver cages are unprecedented. Compound 2 provides a unique example in which two kinds of silver polyhedra with different numbers of vertices (C2@Ag7 and C2@Ag8) co-exist in the crystal structure. [ABSTRACT FROM AUTHOR]

The new silver(I) triple salt 2Ag2C2·AgF·9AgNO3·H2O was prepared by dissolving Ag2C2 in an aqueous solution of AgNO3 and AgBF4. Its crystal structure contains two kinds of monocapped trigonal prismatic C2@Ag7 cages, with the capping atom occurring on one triangular face or one rectangular face. [ABSTRACT FROM AUTHOR]

A 'passivated precursor' approach is developed for the efficient synthesis and isolation of all‐alkynyl‐protected gold nanoclusters. Direct reduction of dpa‐passivated precursor Au‐dpa (Hdpa=2,2'‐dipyridylamine) in one‐pot under ambient conditions gives a series of clusters including Au22(C≡CR)18 (R=−C6H4−2−F), Au36(C≡CR)24, Au44(C≡CR)28, Au130(C≡CR)50, and Au144(C≡CR)60. These clusters can be well separated via column chromatography. The overall isolation yield of this series of clusters is 40 % (based on gold), which is much improved in comparison with previous approaches. It is notable that the molecular structure of the giant cluster Au130(C≡CR)50 is revealed, which presents important information for understanding the structure of the mysterious Au130 nanoclusters. Theoretical calculations indicated Au130(C≡CR)50 has a smaller HOMO‐LUMO gap than Au130(S−C6H4−4−CH3)50. This facile and reliable synthetic approach will greatly accelerate further studies on all‐alkynyl‐protected gold nanoclusters. [ABSTRACT FROM AUTHOR]

A gold(I)‐cluster‐based twin‐cage has been constructed by post‐clustering covalent modification of a hexa‐aldehyde cluster precursor with triaminotriethylamines. The cages‐on‐cluster structure has double cavities and four binding sites, which show site‐discriminative binding for silver(I) and copper(I) guests. The guests in the tripodal hats affect the luminescence of the cluster: the tetra‐silver(I) host–guest complex is weakly red‐emissive, while the bis‐copper(I)‐bis‐silver(I) one is non‐emissive but is a stimuli‐responsive supramolecule. The copper(I) ion inside the tri‐imine cavity is oxidation sensitive, which enables the release of the bright emissive precursor cluster triggered by H2O2 solution. The hybridization of a cluster with cavities to construct a cluster‐based cage presents an innovative concept for functional cluster design, and the post‐clustering covalent modification opens up new avenues for finely tuning the properties of clusters. [ABSTRACT FROM AUTHOR]

Due to the stability issue, It is difficult to prepare a silver nanocluster bearing functional sites, especially at a large scale. We report the synthesis and structure of a stable silver nanocluster bearing multiple surface aldehyde groups [Ag21(Ph2PO2)10(p‐CHOPhC≡C)6]SbF6, which allows for postsynthesis modification such as surface functionalization through aldimine condensation to give homochiral clusters. Remarkably, the preparation of this cluster can be done in ~90 % high yield at gram scale, which facilitates further studies and potential applications. Through DFT calculations and geometric structure analysis, the high stability of this cluster is attributed to the geometric closure and electronic structure. This is the first time that an effective one‐pot method has been developed to synthesize functional silver nanoclusters in high yield. The title cluster will be useful in the development of a variety of cluster‐based materials. [ABSTRACT FROM AUTHOR]

Silver nitrate reacts with sodium azide to give white powdery silver azide, which can be crystallized in aqueous ammonia. The compound belongs to orthorhombic space group Ibam with a = 5.600(1), b = 5.980(6), c = 5.998(1) Å, and Z = 4. The layer-type structure is constructed from edge-sharing regular rectangles, each composed of silver atoms at its vertices with an enclosed azide anion in a tilted orientation. The linear and asymmetrical structure of the azide anion in crystalline silver azide has been confirmed by its Raman spectrum. [ABSTRACT FROM AUTHOR]

A silver alkynyl cluster containing a Ag70 shell and two lacunary [PW9O34]9− templating ions was synthesized by an ionothermal approach. Fast core–shell electronic communication between silver(i) centers and polyoxometalates was verified via cyclic voltammetry studies in [BMIm]BF4. [ABSTRACT FROM AUTHOR]

A Au55 nanocluster with the composition of [Au55(p‐MBT)24(Ph3P)6](SbF6)3 (p‐MBT=4‐methylbenzenethiolate) is synthesized via direct reduction of gold‐phosphine and gold‐thiolate precursors. Single‐crystal X‐ray diffraction reveals that this Au55 nanocluster features a face‐centered cubic (fcc) Au55 kernel, different from the well‐known two‐shell cuboctahedral arrangement in Au55(Ph3P)12Cl6. The Au55 cluster shows a wide optical absorption band with optical energy gap (Eg=1.28 eV). It is found that the exclusion of chloride is crucial for the formation of the title cluster, otherwise rod‐like [Au25(SR)5(PPh3)10Cl2]2+ is obtained. The strategy to run synthetic reaction in the absence of halide leads to new members of phosphine/thiolate co‐protected metal nanoclusters. The Au55 nanocluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO; the Faradaic efficiency (FE) reaches 94.1 % at −0.6 V vs. reversible hydrogen electrode (RHE). [ABSTRACT FROM AUTHOR]

Surface organic ligands are critical in determining the formation and properties of atomically precise metal nanoclusters. In contrast to the conventionally used thiolate, phosphine and alkynyl ligands, the amine ligand dipyridylamine is applied here as a protecting agent in the synthesis of atomically precise metal nanoclusters. We report two homoleptic amido-protected Ag nanoclusters as examples of all-nitrogen-donor-protected metal nanoclusters: [Ag21(dpa)12]SbF6 (Ag21) and [Ag22(dpa)12](SbF6)2 (Ag22) (dpa = dipyridylamido). Single crystal X-ray structural analysis reveals that both clusters consist of a centered-icosahedron Ag13 core wrapped by 12 dpa ligands. The flexible arrangement of the N donors in dpa facilitates the solvent-triggered reversible interconversion between Ag21 and Ag22 due to their very different solubility. The successful use of dpa in the synthesis of well-defined silver nanoclusters may motivate more studies on metal nanoclusters protected by amido type ligands. Noble metal nanoclusters are commonly protected by thiolate, phosphine, or alkynyl ligands. Here, the authors synthesize two homoleptic amido-protected silver clusters, whose structures interconvert easily with changes of solvent due to the coordination flexibility and diverse binding modes of the nitrogen-donor ligands. [ABSTRACT FROM AUTHOR]

Hollow nanoclusters are intriguing for bridging the gap between small metal-organic cages and hollow nanoparticles and provide enormous opportunities for functional materials. Rational construction of hollow nanoclusters remains a challenge owing to the poor understanding of their formation pathways and difficulties in obtaining the intermediate structures. Here we report a catalyzed assembly strategy to construct hollow silver–sulfide clusters using a self-releasable carbonate template. The hollow Ag56 cluster and the carbonate-templated Ag33 intermediate are characterized by single-crystal X-ray analysis. Combining this data with a time-dependent UV-Vis spectroscopic investigation, we reveal the catalyst-like behavior of the self-releasable carbonate template and propose the corresponding mechanism. The assembly of hollow clusters using a self-releasable template may provide insight into understanding the formation mechanisms of other hollow nanoclusters and facilitate the design and construction of new hollow nanoclusters. The rational construction of hollow nanostructures is challenging owing to difficulties in elucidating formation pathways and observing intermediates. Here the authors probe the formation of the hollow Ag56 cluster and identify a catalyst-like self-releasing template formation mechanism. [ABSTRACT FROM AUTHOR]