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1.
Synthesis of atom‐precise alloy nanoclusters with uniform composition is challenging when the alloying atoms are similar in size (for example, Ag and Au). A galvanic exchange strategy has been devised to produce a compositionally uniform [Ag24Au(SR)18]? cluster (SR: thiolate) using a pure [Ag25(SR)18]? cluster as a template. Conversely, the direct synthesis of Ag24Au cluster leads to a mixture of [Ag25?xAux(SR)18]?, x=1–8. Mass spectrometry and crystallography of [Ag24Au(SR)18]? reveal the presence of the Au heteroatom at the Ag25 center, forming Ag24Au. The successful exchange of the central Ag of Ag25 with Au causes perturbations in the Ag25 crystal structure, which are reflected in the absorption, luminescence, and ambient stability of the particle. These properties are compared with those of Ag25 and Ag24Pd clusters with same ligand and structural framework, providing new insights into the modulation of cluster properties with dopants at the single‐atom level.  相似文献   

2.
Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size‐evolution principles. Reported here is the largest known FCC‐based (FCC=face centered cubic) silver nanocluster, [Ag100(SC6H33,4F2)48(PPh3)8]?: the first all‐octahedral symmetric nesting Ag nanocluster with a four‐layered Ag6@Ag38@Ag48S24@Ag8S24P8 structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC‐based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC‐based Russian nesting doll model constitutes a new platform for the study of the size‐evolution principles of Ag NCs.  相似文献   

3.
Decreasing the core size is one of the best ways to study the evolution from AuI complexes into Au nanoclusters. Toward this goal, we successfully synthesized the [Au18(SC6H11)14] nanocluster using the [Au18(SG)14] (SG=L ‐glutathione) nanocluster as the starting material to react with cyclohexylthiol, and determined the X‐ray structure of the cyclohexylthiol‐protected [Au18(C6H11S)14] nanocluster. The [Au18(SR)14] cluster has a Au9 bi‐octahedral kernel (or inner core). This Au9 inner core is built by two octahedral Au6 cores sharing one triangular face. One transitional gold atom is found in the Au9 core, which can also be considered as part of the Au4(SR)5 staple motif. These findings offer new insight in terms of understanding the evolution from [AuI(SR)] complexes into Au nanoclusters.  相似文献   

4.
The first atomically and structurally precise silver‐nanoclusters stabilized by Se‐donor ligands, [Ag20{Se2P(OiPr)2}12] ( 3 ) and [Ag21{Se2P(OEt)2}12]+( 4 ), were isolated by ligand replacement reaction of [Ag20{S2P(Oi Pr)2}12] ( 1 ) and [Ag21{S2P(Oi Pr)2}12]+ ( 2 ), respectively. Furthermore, doping reactions of 4 with Au(PPh3)Cl resulted in the formation of [AuAg20{Se2P(OEt)2}12]+ ( 5 ). Structures of 3 , 4 , and 5 were determined by single‐crystal X‐ray diffraction. The anatomy of cluster 3 with an Ag20 core having C 3 symmetry is very similar to that of its dithiophosphate analogue 1 . Clusters 4 and 5 exhibit an Ag21 and Au@Ag20 core of Oh symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag13 and Au@Ag12 centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen‐passivated silver nanoparticles, which have been theoretically confirmed as 8‐electron superatoms.  相似文献   

5.
The reduction of alkynyl-silver and phosphine-silver precursors with a weak reducing reagent Ph2SiH2 led to the formation of a novel silver nanocluster [Ag93(PPh3)6(C≡CR)50]3+ (R=4-CH3OC6H4), which is the largest structurally characterized cluster of clusters. This disc-shaped cluster has a Ag69 kernel consisting of a bicapped hexagonal prismatic Ag15 unit wrapped by six Ino decahedra through edge-sharing. This is the first time that Ino decahedra are used as a building block to assemble a cluster of clusters. Moreover, the central silver atom has a coordination number of 14, which is the highest in metal nanoclusters. This work provides a diverse metal packing pattern in metal nanoclusters, which is helpful for understanding metal cluster assembling mechanisms.  相似文献   

6.
Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size-evolution principles. Reported here is the largest known FCC-based (FCC=face centered cubic) silver nanocluster, [Ag100(SC6H33,4F2)48(PPh3)8]: the first all-octahedral symmetric nesting Ag nanocluster with a four-layered Ag6@Ag38@Ag48S24@Ag8S24P8 structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC-based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC-based Russian nesting doll model constitutes a new platform for the study of the size-evolution principles of Ag NCs.  相似文献   

7.
Gas‐phase photoelectron spectroscopy (PES) was conducted on [XAg24(SPhMe2)18]? (X=Ag, Au) and [YAg24(SPhMe2)18]2? (Y=Pd, Pt), which have a formal superatomic core (X@Ag12)5+ or (Y@Ag12)4+ with icosahedral symmetry. PES results show that superatomic orbitals in the (Au@Ag12)5+ core remain unshifted with respect to those in the (Ag@Ag12)5+ core, whereas the orbitals in the (Y@Ag12)4+ (Y = Pd, Pt) core shift up in energy by about 1.4 eV. The remarkable doping effect of a single Y atom (Y=Pd, Pt) on the electronic structure of the chemically modified (Ag@Ag12)5+ superatom was reproduced by theoretical calculations on simplified model systems and was ascribed to 1) the weaker binding of valence electrons in Y@(Ag+)12 compared to Ag+@(Ag+)12 due to the reduction in formal charge of the core potential, and 2) the upward shift of the apparent vacuum level due to the presence of a repulsive Coulomb barrier between [YAg24(SPhMe2)18]? and electron.  相似文献   

8.
The synthesis of Naumann's AgI/AgIII mixed valence salt [AgI]+[AgIII(CF3)4] ( Ag-1 ) is revisited. Ag-1 is now safely available in half gram scale upon 2e oxidation of AgF in presence of CF3SiMe3 and ambient air. In addition to its unprecedented crystallographic characterization, the use of Ag-1 to build the novel AgI/AgIII salts [ Ag (bpy)2] -1 , [ Ag (18-crown-6)2] -1 , [ Ag -crypt-222] -1 and [ Ag (PCy3)2] -1 is herein reported, alongside their characterization by NMR, single crystal X-ray diffraction (Sc-XRD) and elemental analysis (EA). The utility of the currently affordable Ag-1 in gold(I) catalysis was demonstrated by the excellent catalytic activity displayed by [{ Au (PPh3)}2(μ-Cl)] -1 and [ Au (PPh3)] -1 in the 5-exo-dig cyclization of N-propargylbenzamide ( 2 ). These cationic AuI catalysts are accessible from (PPh3)AuCl and Ag-1 , and outperform the activity of the well-known benchmark catalyst (PPh3)AuNTf2.  相似文献   

9.
The synthesis and structure of atomically precise Au130?xAgx (average x=98) alloy nanoclusters protected by 55 ligands of 4‐tert‐butylbenzenethiolate are reported. This large alloy structure has a decahedral M54 (M=Au/Ag) core. The Au atoms are localized in the truncated Marks decahedron. In the core, a drum of Ag‐rich sites is found, which is enclosed by a Marks decahedral cage of Au‐rich sites. The surface is exclusively Ag?SR; X‐ray absorption fine structure analysis supports the absence of Au?S bonds. The optical absorption spectrum shows a strong peak at 523 nm, seemingly a plasmon peak, but fs spectroscopic analysis indicates its non‐plasmon nature. The non‐metallicity of the Au130?xAgx nanocluster has set up a benchmark to study the transition to metallic state in the size evolution of bimetallic nanoclusters. The localized Au/Ag binary architecture in such a large alloy nanocluster provides atomic‐level insights into the Au?Ag bonds in bimetallic nanoclusters.  相似文献   

10.
The [AuxAg16-x(SAdm)8(Dppe)2] nanocluster with aggregation-induced emission (AIE) was synthesized from a non-fluorescent [Au9Ag12(SAdm)4(Dppm)6Cl6](SbF6)3 nanocluster via a ligand-exchange engineering (Dppe=1,2-Bis(diphenylphosphino)ethane, Dppm=Bis(diphenylphosphino)methane, HSAdm=1-Adamantanethiol). The nanocluster has a Au-doped icosahedral AuxAg13-x core, capped by two Ag(SR)3, one Ag(SR)2 and two Dppe ligands. By changing the achiral Dppe ligand into a chiral dbpb ligand ((2S,3S)-(-)-Bis(diphenylphosphino)butane or (2R,3R)-(+)-2,3-Bis(diphenylphosphino)butane), chiral nanoclusters are obtained. ESI-MS and UV-vis spectroscopy were performed to track the reaction. This work provides guidance for the construction of new clusters by etching clusters with multidentate phosphine ligands.  相似文献   

11.
The X-ray structural study of the reaction product of equimolar amounts of [Au3Cu2(C2Ph)6]. [{Au(C2Ph)} n ], and [Ag(C2Ph)} n ] revealed two bimetallic anionic [N(PPh3)2] + [Au3Ag2(C2Ph)6] and [N(PPh3)2]+[Au3Cu2 (C2 Pg)6] — clusters co-crystallized in one asymmetric unit. Each cluster has trigonal bipyramidal geometry with three gold atoms occupying equatorial planes and two silver or copper atoms in the apical positions. Our earlier conclusion based upon spectroscopic characterization describing the product of be above reaction as trimetallic cluster containing three coinage-metals with an overall composition [Au3CuAg(C2Ph)6], was erroneous.Presented at the 210th ACS Meeting, August 19–24, 1995, Chicago, Illinois.  相似文献   

12.
The assembly of atomically precise metal nanoclusters offers exciting opportunities to gain fundamental insights into the hierarchical assembly of nanoparticles. However, it is still challenging to control the assembly of individual nanoclusters at a molecular or atomic level. Herein, we report the dimeric assembly of Au25(PET)18 (PET=2‐phenylethanethiol), where two Au25(PET)18 monomers are bridged together by two Ag atoms to form the Ag2Au50(PET)36 dimer. The Ag2Au50(PET)36 dimer is a unique mesomer, which has not been found in any other chiral metal nanoclusters. Furthermore, the Ag2Au50(PET)36 dimer is distinct from the Au25(PET)18 monomer in its optical, electronic, and catalytic properties. This study is expected to provide a feasible strategy to precisely modulate the assembly of metal nanoclusters with controllable structures and properties.  相似文献   

13.
Small Agn nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face‐centered‐cubic‐type small {Ag7}5+ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si3W27O96]18?. The cluster showed unique {Ag7}5+‐to‐POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag7}5+ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O2, water, and solvents.  相似文献   

14.
The conventional synthetic methodology for atomically precise gold nanoclusters by using reduction in solution offers only the thermodynamically most stable nanoclusters. Herein, a solubility-driven isolation strategy is reported to access a metastable gold cluster. The cluster, with the composition of [Au9(PPh3)8]+ ( 1 ), displays an unusual, nearly perfect body-centered cubic (bcc) structure. As revealed by ESI-MS and UV/Vis measurements, the cluster is metastable in solution and converts to the well-known [Au11(PPh3)8Cl2]+ ( 2 ) within just 90 min. DFT calculations revealed that although both 1 and 2 are eight-electron superatoms, there is a driving force to convert 1 to 2 as shown by the increased cohesion and larger HOMO–LUMO energy gap of 2 . The isolation and crystallization of the metastable gold cluster were achieved in a biphasic reaction system in which reduction of gold precursors and crystallization of 1 took place concurrently. This synthetic protocol represents a successful strategy for investigations of other metastable species in metal nanocluster chemistry.  相似文献   

15.
For the first time site-specific doping of silver into a spherical Au25 nanocluster has been achieved in [Au19Ag6(MeOPhS)17(PPh3)6] (BF4)2 (Au19Ag6) through a dual-ligand coordination strategy. Single crystal X-ray structural analysis shows that the cluster has a distorted centered icosahedral Au@Au6Ag6 core of D3 symmetry, in contrast to the Ih Au@Au12 kernel in the well-known [Au25(SR)18] (R = CH2CH2Ph). An interesting feature is the coexistence of [Au2(SPhOMe)3] dimeric staples and [P–Au–SPhOMe] semi-staples in the title cluster, due to the incorporation of PPh3. The observation of only one double-charged peak in ESI-TOF-MS confirms the ordered doping of silver atoms. Au19Ag6 is a 6e system showing a distinct absorption spectrum from [Au25(SR)18], that is, the HOMO–LUMO transition of Au19Ag6 is optically forbidden due to the P character of the superatomic frontier orbitals.

For the first time site-specific doping of silver into a spherical Au25 nanocluster has been achieved in [Au19Ag6(MeOPhS)17(PPh3)6] (BF4)2. It is a 6e system showing quite a different absorption spectrum from [Au25(SR)18].  相似文献   

16.
The betain‐like carbodiphosphorane CS2 adduct S2CC(PPh3)2 ( 1 ) reacts with Ag(I) salts which contain weakly coordinating anions such as [BF4]? or [Al{OC(CF3)3}4]? to produce the cluster compounds [Ag6{S2CC(PPh3)2}4][BF4]6 ( 2 ) and [Ag4{S2CC(PPh3)2}4][Al{OC(CF3)3}4]4 ( 3 ), respectively, as orange yellow crystals containing solvent molecules. In the solid state the Ag4 unit in 3 forms a tetrahedron, and in the Ag6 core of 2 two of the opposite edges of the tetrahedron are bridged by Ag+ ions. The clusters are held together by argentophilic interactions, and each sulfur atom of 1 is coordinated to four (as in 2 ) or three (as in 3 ) silver atoms. The compounds are characterized by IR and 31P NMR spectroscopic studies and by X‐ray diffraction analyses.  相似文献   

17.
Herein, we report the synthesis and atomic structure of the cluster‐assembled [Au60Se2(Ph3P)10(SeR)15]+ material. Five icosahedral Au13 building blocks from a closed gold ring with Au–Se–Au linkages. Interestingly, two Se atoms (without the phenyl tail) locate in the center of the cluster, stabilized by the Se‐(Au)5 interactions. The ring‐like nanocluster is unprecedented in previous experimental and theoretical studies of gold nanocluster structures. In addition, our optical and electrochemical studies show that the electronic properties of the icosahedral Au13 units still remain unchanged in the penta‐twinned Au60 nanocluster, and this new material might be a promising in optical limiting material. This work offers a basis for deep understanding on controlling the cluster‐assembled materials for tailoring their functionalities.  相似文献   

18.
In a new oxidative route, Ag+[Al(ORF)4]? (RF=C(CF3)3) and metallic indium were sonicated in aromatic solvents, such as fluorobenzene (PhF), to give a precipitate of silver metal and highly soluble [In(PhF)n]+ salts (n=2, 3) with the weakly coordinating [Al(ORF)4]? anion in quantitative yield. The In+ salt and the known analogous Ga+[Al(ORF)4]? were used to synthesize a series of homoleptic PR3 phosphane complexes [M(PR3)n]+, that is, the weakly PPh3‐bridged [(Ph3P)3In–(PPh3)–In(PPh3)3]2+ that essentially contains two independent [In(PPh3)3]+ cations or, with increasing bulk of the phosphane, the carbene‐analogous [M(PtBu3)2]+ (M=Ga, In) cations. The MI? P distances are 27 to 29 pm longer for indium, and thus considerably longer than the difference between their tabulated radii (18 pm). The structure, formation, and frontier orbitals of these complexes were investigated by calculations at the BP86/SV(P), B3LYP/def2‐TZVPP, MP2/def2‐TZVPP, and SCS‐MP2/def2‐TZVPP levels.  相似文献   

19.
Building framework materials with desirable properties and enhanced functionalities with nanocluster/superatom complexes as building blocks remains a challenge in the field of nanomaterials. In this study, the chiral [Au1Ag22(S‐Adm)12]3+ nanocluster/superatom complex (SC, in which S‐Adm=1‐adamantanethiol) was employed as a building block to construct the three‐dimensional (3D) superatom complex inorganic framework (SCIF) materials SCIF‐1 and SCIF‐2 through inorganic SbF6? linkers. SCIF‐1 is racemic due to the assembly of two SC enantiomers in a single crystal. In SCIF‐2, the SC enantiomers are packed in separate crystals, thus producing larger channels and a circularly polarized luminescence (CPL) response. These two 3D SCIF materials exhibit unique sensitive photoluminescence (PL) in protic solvents. Our study provides a new pathway for creating novel open‐framework materials with superatom complexes and a foundation for the further development of 3D framework materials for sensing and other applications.  相似文献   

20.
Aurophilic interactions (AuI???AuI) are crucial in directing the supramolecular self‐assembly of many gold(I) compounds; however, this intriguing chemistry has been rarely explored for the self‐assembly of nanoscale building blocks. Herein, we report on studies on aurophilic interactions in the structure‐directed self‐assembly of ultrasmall gold nanoparticles or nanoclusters (NCs, <2 nm) using [Au25(SR)18]? (SR=thiolate ligand) as a model cluster. The self‐assembly of NCs is initiated by surface‐motif reconstruction of [Au25(SR)18]? from short SR‐[AuI‐SR]2 units to long SR‐[AuI‐SR]x (x>2) staples accompanied by structure modification of the intrinsic Au13 kernel. Such motif reconstruction increases the content of AuI species in the protecting shell of Au NCs, providing the structural basis for directed aurophilic interactions, which promote the self‐assembly of Au NCs into well‐defined nanoribbons in solution. More interestingly, the compact structure and effective aurophilic interactions in the nanoribbons significantly enhance the luminescence intensity of Au NCs with an absolute quantum yield of 6.2 % at room temperature.  相似文献   

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