A platonic solid templating Archimedean solid: an unprecedented nanometre-sized Ag37 cluster

Chemical Flexibility of Atomically Precise Metal Clusters

Ligand-protected metal clusters possess hybrid properties that seamlessly combine an inorganic core with an organic ligand shell, imparting them exceptional chemical flexibility and unlocking remarkable application potential in diverse fields. Leveraging chemical flexibility to expand the library of available materials and stimulate the development of new functionalities is becoming an increasingly pressing requirement. This Review focuses on the origin of chemical flexibility from the structural analysis, including intra-cluster bonding, inter-cluster interactions, cluster-environments interactions, metal-to-ligand ratios, and thermodynamic effects. In the introduction, we briefly outline the development of metal clusters and explain the differences and commonalities of M(I)/M(I/0) coinage metal clusters. Additionally, we distinguish the bonding characteristics of metal atoms in the inorganic core, which give rise to their distinct chemical flexibility. Section 2 delves into the structural analysis, bonding categories, and thermodynamic theories related to metal clusters. In the following sections 3 to 7, we primarily elucidate the mechanisms that trigger chemical flexibility, the dynamic processes in transformation, the resultant alterations in structure, and the ensuing modifications in physical-chemical properties. Section 8 presents the notable applications that have emerged from utilizing metal clusters and their assemblies. Finally, in section 9, we discuss future challenges and opportunities within this area.

Polyhedral {Ag12} and {Ag16} Clusters: Synthesis, Structural Characterization and Third-Order Nonlinear Optical Properties

Two polyhedral silver-thiolate clusters, [S@Ag16(Tab)10(MeCN)8](PF6)14 (Ag16) and [Ag12(Tab)6(DMF)12](PF6)12 (Ag12), were synthesized by using electroneutral Tab species as protective ligands (Tab=4-(trimethylammonio)benzenethiolate, DMF=N,N-dimethylformamide, MeCN=acetonitrile). Ag16 has a decahedral shape composed of eight pentagon {Ag5} units and two square {Ag4} units. The structure of Ag12 is a cuboctahedron, a classical Archimedean structure composed of six triangular faces and eight square faces. The former configuration is discovered in silver-thiolate cluster for the first time, possibly benefited from the more flexible coordination between the Tab ligand and Ag+ facilitated by the electropositive -N(CH3)3 + substituent group. Third-order nonlinear optical studies show that both clusters in DMF exhibit reverse saturate absorption response under the irradiation of 532 nm laser.

Platonic and Archimedean solids in discrete metal-containing clusters

Metal-containing clusters have attracted increasing attention over the past 2-3 decades. This intense interest can be attributed to the fact that these discrete metal aggregates, whose atomically precise structures are resolved by single-crystal X-ray diffraction (SCXRD), often possess intriguing geometrical features (high symmetry, aesthetically pleasing shapes and architectures) and fascinating physical properties, providing invaluable opportunities for the intersection of different disciplines including chemistry, physics, mathematical geometry and materials science. In this review, we attempt to reinterpret and connect these fascinating clusters from the perspective of Platonic and Archimedean solid characteristics, focusing on highly symmetrical and complex metal-containing (metal = Al, Ti, V, Mo, W, U, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, lanthanoids (Ln), and actinoids) high-nuclearity clusters, including metal-oxo/hydroxide/chalcogenide clusters and metal clusters (with metal-metal binding) protected by surface organic ligands, such as thiolate, phosphine, alkynyl, carbonyl and nitrogen/oxygen donor ligands. Furthermore, we present the symmetrical beauty of metal cluster structures and the geometrical similarity of different types of clusters and provide a large number of examples to show how to accurately describe the metal clusters from the perspective of highly symmetrical polyhedra. Finally, knowledge and further insights into the design and synthesis of unknown metal clusters are put forward by summarizing these "star" molecules.

Sulfide Boosting Near-Unity Photoluminescence Quantum Yield of Silver Nanocluster

Silver nanoclusters have emerged as promising candidates for optoelectronic applications, but their room-temperature photoluminescence quantum yield (PLQY) is far from ideal to access cutting-edge device performance. Herein, two supertetrahedral silver nanoclusters with high PLQY in non-degassed solution at room temperature were constructed by interiorly supporting the core with multiple VO₄^3- and E^2- anions as structure-directing agents and exteriorly protecting the core with a rigid ligand shell of PhC≡C^- and Ph₂PE₂^- (E = S, Ag64-S; E = Se, Ag64-Se). Both clusters have similar outer Ag₅₈ tetrahedral cages and [Ag₆E₄@(VO₄)₄] cores, forming a pair of comparable clusters to decrypt the origin of such a high PLQY, particularly in Ag64-S, where the PLQY reached up to 97%. The stronger suppression effect of inner sulfides for nonradiative decay is critical to boost the PLQY to near unity. Transient absorption spectroscopy is employed to confirm the phosphorescence nature. The quadruple-capping assembly mechanism involving Ag₇ secondary building units on a Ag₃₆ truncated tetrahedron was also established by collision-induced dissociation studies. This work not only provides a strategy of core engineering for the controlled syntheses of silver nanoclusters with high PLQY but also deciphers the origin of a near-unity PLQY, which lays a foundation for fabricating highly phosphorescent silver nanoclusters in the future.

Silver-Rich Hybrid Framework Iodide Based on [Ag8I6]2+ Clusters Displays Low-Temperature Dual Emission and Luminescence Thermochromism

Cluster-based framework metal iodides have diverse structures and excellent luminescence properties, and show promising applications in sensing and solid-state lighting. However, the design and synthesis of these materials remain great challenges because excess I^- ions introduced into the synthesis systems decrease the condensation degree of M-I units. In this work, a new strategy is developed to control the condensation behavior of Ag-I units, and a new silver-rich cluster-based framework iodide [DabcoAg₈I₆(SPh)₂]_n (1) (Dabco = 1,4-diazabicyclo [2.2.2] octane) has been synthesized under solvothermal conditions in the presence of silver thiophenolate (AgSPh)_n. Compound 1 features a three-dimensional (3-D) cluster-based framework with a pillared layer structure composed of cationic [Ag₈I₆]²⁺ clusters bridged by SPh^- and Dabco, and displays low-temperature dual emission and luminescence thermochromism.

Stepwise Assembly of Ag42 Nanocalices Based on a MoVI-Anchored Thiacalix[4]arene Metalloligand

Metalloligand strategy has been well recognized in the syntheses of heterometallic coordination polymers; however, such a strategy used in the assembly of silver nanoclusters is not broadly available. Herein, we report the stepwise syntheses of a family of halogen-templated Ag₄₂ nanoclusters (Ag42c-Ag42f) based on Mo^VI-anchored p-tert-butylthiacalix[4]arene (H₄TC4A) as a metalloligand (hereafter named MoO₃-TC4A). X-ray crystallography demonstrates that they are similar C₃-symmetric silver-organic nanocalices capped by six MoO₃-TC4A metalloligands, which are evenly distributed up and down the base of 42 silver atoms. These nanoclusters can be disassembled to six bowl-shaped [Ag₁₁(MoO₃-TC4A)(RS)₃] secondary building units (SBUs, R = Et or ⁿPr), which are fused together in a face-sharing fashion surrounding Cl^- or Br^- as a central anion template. The electrospray mass spectrometry (ESI-MS) indicates their high stabilities in solution and verifies the formation of the MoO₃-TC4A metalloligand, thereby rationalizing the overall stepwise assembly process for them. Moreover, Ag42c shows lower cytotoxicity and better activity against the HepG-2 cell line than MCF-7 and BGC-823. These results not only exemplify the effectiveness of a thiacalix[4]arene-based metalloligand in the assembly of silver nanoclusters but also give us profound insight about the step-by-step assembly process in silver nanoclusters.

Small symmetry-breaking triggering large chiroptical responses of Ag70 nanoclusters

The origins of the chiroptical activities of inorganic nanostructures have perplexed scientists, and deracemization of high-nuclearity metal nanoclusters (NCs) remains challenging. Here, we report a single-crystal structure of Rac-Ag₇₀ that contains enantiomeric pairs of 70-nuclearity silver clusters with 20 free valence electrons (Ag₇₀), and each of these clusters is a doubly truncated tetrahedron with pseudo-T symmetry. A deracemization method using a chiral metal precursor not only stabilizes Ag₇₀ in solution but also enables monitoring of the gradual enlargement of the electronic circular dichroism (CD) responses and anisotropy factor g_abs. The chiral crystals of R/S-Ag₇₀ in space group P2₁ containing a pseudo-T-symmetric enantiomeric NC show significant kernel-based and shell-based CD responses. The small symmetry breaking of T_d symmetry arising from local distortion of Ag−S motifs and rotation of the apical Ag₃ trigons results in large chiroptical responses. This work opens an avenue to construct chiral medium/large-sized NCs and nanoparticles, which are promising for asymmetric catalysis, nonlinear optics, chiral sensing, and biomedicine.

Having control over the chirality of metal nanoclusters is challenging. Here, the authors report the deracemization of silver nanoclusters and monitor the chiroptical responses.

Trapping a [W10O32]6- decatungstate anion in an Ag44 nanowheel

Compound [Ag 44 (W 10 O 32 )(S t Bu) 24 (CF 3 COO) 8 ](CF 3 COO) 6 ·6H 2 O ( 1 ) was synthesized through the one-pot method, which is the first case of isolating a new silver thiolate cluster containing a [W 10 O 32 ] 6- template which transforms from WO 4 2- polyoxoanion through a self-assembly process. The anionic nature of the reduced [W 10 O 32 ] 6- template and the effective silver-oxygen interaction contribute to the formation of the Ag 44 nanowheel in 1 . The luminescence, photocatalytic activity and electrochemistry properties of 1 were studied.

Thermally Hypsochromic or Bathochromic Emissions? The Silver Nuclei Does Matter

Structural modulation of core-shell silver nanoclusters from the inside is a huge challenge but of great importance in their syntheses. Herein, two silver nanoclusters [Ag₃ S₉ @Ag₄₂ ] (SD/Ag45b) and [Ag₉ S₉ @Ag₄₂ ] (SD/Ag51a) are isolated in the presence of different kinds of sulfonic acids. Uniquely, SD/Ag45b and SD/Ag51a show typical core-shell structures with the similar Ag₄₂ shell but different cores. The outer shell of 42 silver atoms comprises two Ag₃ trigons at two poles encircled by three equatorial distorted square cupolas (J₄ , Ag₁₂ ). The core in SD/Ag45b is a silver trigon ligated by nine S^2- ions (Ag₃ S₉ ), while a tricapped triangular prismatic Ag₉ also ligated by the same amount of S^2- ions (Ag₉ S₉ ) is observed in the inner core of SD/Ag51a. The electrospray ionization mass spectrometry (ESI-MS) indicates that the introduction of p-toluenesulfonic acid can realize the transformation from SD/Ag45b to Ag₅₁ . SD/Ag45b and SD/Ag51a show inverse luminescence thermochromic behaviors in the near-infrared (NIR) region, mainly dictated by the inner silver cores. This work not only realizes the synthesis of new silver nanoclusters by core modulation but also provides a prototype to get molecular-level insight into the correlation between structure and luminescence thermochromism.

Atomically precise metal chalcogenide supertetrahedral clusters: frameworks to molecules, and structure to function

Metal chalcogenide supertetrahedral clusters (MCSCs) are of significance for developing crystalline porous framework materials and atomically precise cluster chemistry. Early research interest focused on the synthetic and structural chemistry of MCSC-based porous semiconductor materials with different cluster sizes/compositions and their applications in adsorption-based separation and optoelectronics. More recently, focus has shifted to the cluster chemistry of MCSCs to establish atomically precise structure-composition-property relationships, which are critical for regulating the properties and expanding the applications of MCSCs. Importantly, MCSCs are similar to II-VI or I-III-VI semiconductor nanocrystals (also called quantum dots, QDs) but avoid their inherent size polydispersity and structural ambiguity. Thus, discrete MCSCs, especially those that are solution-processable, could provide models for understanding various issues that cannot be easily clarified using QDs. This review covers three decades of efforts on MCSCs, including advancements in MCSC-based open frameworks (reticular chemistry), the precise structure-property relationships of MCSCs (cluster chemistry), and the functionalization and applications of MCSC-based microcrystals. An outlook on remaining problems to be solved and future trends is also presented.

Structural rearrangement of Ag60 nanocluster endowing different luminescence performances

It is well known that structure determines property, but obtaining a pair of silver nanoclusters with comparable structures to understand the structure-property relationship is a very challenging task. A new 60-nuclei silver nanocluster (SD/Ag60a) protected by a mixed-ligand shell of ^tBuS^- and o-CH₃OPhCOO^- was obtained and characterized. Single crystal x-ray diffraction reveals that SD/Ag60a has an identical metal nuclearity and core-shell structural type to SD/Ag1 previously reported by our group, whereas the compositions of the core and shell have undergone a rearrangement from an Ag₁₂ cuboctahedron core and an Ag₄₈ rhombicuboctahedron shell in SD/Ag1 to an Ag₁₄ rhombic dodecahedron core and an oval Ag₄₆ shell in SD/Ag60a. The core enlargement from Ag₁₂ to Ag₁₄ originates from the replacement of two S^2- in Ag₁₂S₁₅ by two Ag⁺, which gives a new Ag₁₄S₁₃ core. This result indicates that the metal frameworks of silver nanoclusters have some extent flexibility despite the same nuclearity, which can be influenced by ligands, solvents, anion templates, and others in the embryonic stage of the assembly. Interestingly, different core-shell architectures of Ag₆₀ nanoclusters also significantly endow the different optical absorption bands, photocurrent-generating properties, and luminesecent behaviors. This work not only realizes the regulation of the core-shell structure of silver nanoclusters with the same nuclearity but also provides a comparable model for investigating the relationship of structure-photoelectric properties.

New 3D Porous Silver Nanopolycluster as a Highly Effective Supercapacitor Electrode: Synthesis and Study of the Optical and Electrochemical Properties

A high-nucleus silver nanopolycluster as a new type of silver-based polymer supercapacitor (SSc) by a simple and single-step synthesis process was designed and synthesized. The structural, optical, and electrochemical properties of SSc-2 were determined. This highly stable conductive 3D nanopolycluster shows great cycling stability, large capacity, and high energy density without any modification or doping process and so acts as an excellent SSc (412 F g^-1 at 1.5 A g^-1). In addition, there was a stable cycling performance (94% capacitance) following 7000 cycles at 3 A g^-1 current density. The presence of fluorinated groups, 3D expansion of high-nucleus metallic clusters, and porosity are the advantages of SSc-2 that lead to stability, conductivity, and high capacity, respectively. These results lead to the development of a novel kind of SSc by overcoming the low conductivity and limited capacity challenges without any modification.

Trinuclear cationic silver nanoclusters based-on bis-(phosphine) ligands and stabilized by CF3SO3− anions

Three trinuclear cationic silver nanoclusters based-on bis-(phosphine) ligands and stabilized by CF₃SO₃⁻ anions, displayed excellent photocurrent responses and electrochemical properties.

The interesting luminescence behavior and rare nonlinear optical properties of the {Ag55Mo6} nanocluster

The reversible thermochromic luminescence and rare third-order NLO properties of the {Ag55Mo6} nanocluster reported were studied experimentally, and the contributions of Ag+, CC− and MoO42− groups to NLO properties were proved by DFT calculations.

Tetrahedral Geometry Induction of Stable Ag-Ti Nanoclusters by Flexible Trifurcate TiL3 Metalloligand

A series of increasingly large silver nanoclusters with a varied combination of Archimedean and/or Platonic solid arrangements was constructed using a flexible trifurcate TiL₃ (L = Salicylic acid or 5-fluorosalicylic acid) metalloligand: Ag₄@Ag₄@Ti₄ (PTC-85), Ag₁₂@Ti₄ (PTC-86), Ag₄@Ag₆@Ag₁₂@Ti₄ (PTC-87), Ag₆@Ag₂₄@Ag₁₂@Ti₄ (PTC-88), and Ag₁₂@Ag₂₄@Ti₄ (PTC-89). The silver nanoclusters are each capped by four TiL₃ moieties, thereby forming {Ti₄} supertetrahedra with average edge lengths ranging from ∼8.12 Å to ∼17.37 Å. Such {Ti₄} moieties further induce the tetrahedral geometry of the encapsulated silver nanoclusters. These atomically precise metallic clusters were found to be ultrastable with respect to air for several months, and to water for more than 3 days, due to the stabilizing effects of the TiL₃ metalloligand. Moreover, the obtained clusters exhibit nonlinear optical (NLO) effects in optical limiting tests and also temperature-dependent photoluminescent properties. This work provides an interesting metalloligand method not only to induce the spatial growth of metallic clusters to achieve highly symmetric structures, but also to enhance their stability which is crucial for future application.

A hierarchically assembled 88-nuclei silver-thiacalix[4]arene nanocluster

Thiacalix[4]arenes as a family of promising ligands have been widely used to construct polynuclear metal clusters, but scarcely employed in silver nanoclusters. Herein, an anion-templated Ag₈₈ nanocluster (SD/Ag88a) built from p-tert-butylthiacalix[4]arene (H₄TC4A) is reported. Single-crystal X-ray diffraction reveals that C₄-symmetric SD/Ag88a resembles a metal-organic super calix comprised of eight TC4A⁴⁻ as walls and 88 silver atoms as base, which can be deconstructed to eight [CrO₄@Ag₁₁(TC4A)(EtS)₄(OAc)] secondary building units arranged in an annulus encircling a CrO₄²⁻ in the center. Local and global anion template effects from chromates are individually manifested in SD/Ag88a. The solution stability and hierarchical assembly mechanism of SD/Ag88a are studied by using electrospray mass spectrometry. The Ag₈₈ nanocluster represents the highest nuclearity metal cluster capped by TC4A⁴⁻. This work not only exemplify the specific macrocyclic effects of TC4A⁴⁻ in the construction of silver nanocluster but also realize the shape heredity of TC4A⁴⁻ to overall silver super calix.

The assembly of giant silver clusters by using macrocylic multidentate ligand remains a challenge. Here, the authors synthesize a chromate-templated 88-nuclei silver super calix and reveal the role of anion templating effects and a hierarchical assembly mechanism.

A new silver cluster that emits bright-blue phosphorescence

A new stable hexanuclear silver(i) cluster features brightly blue phosphorescence at room temperature, which is integrated with yellow phosphors (YAG:Ce³⁺) to white-light-emission film and demonstrates interesting mechanoresponsive luminescence.

A stably discrete 31-nuclearity silver(i) thiolate nanocluster luminescent thermometer supported by DMF auxiliary ligands

The stably discrete [Ag₃₁S₃(S^tBu)₁₇(CF₃COO)₇(CO₃)_0.5(CF₃COOH)_0.5(DMF)₄] nanocluster in Ag31S20-DMF (1) shaped in a turtle-like structure exhibits temperature-sensitive luminescence properties.

A 2D layer network assembled from an open dendritic silver cluster Cl@Ag11N24 and an N-donor ligand

A 2D layer network was synthesized from an N-donor ligand and a new silver cluster featuring an open dendritic structure with a high coordination ratio of N atom. Both the assembly process and luminescence properties of this complex was studied.

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.

Photoluminescence modulation of an atomically precise silver(i)-thiolate cluster via site-specific surface engineering

A series of pyridyl ligand functionalized silver-thiolate nanoclusters with an identical cuboctahedron Ag12 core were prepared through site-specific surface engineering and fully characterized. Their wide-range photoluminescence modulation was systematically studied.

Deciphering synergetic core-shell transformation from [Mo6O22@Ag44] to [Mo8O28@Ag50]

The structural transformation of high-nuclearity silver clusters from one to another induced by specific stimuli is of scientific significance in terms of both cluster synthesis and reactivity. Herein, we report two silver-thiolate clusters, [Mo₆O₂₂@Ag₄₄] and [Mo₈O₂₈@Ag₅₀], which are templated by isopolymolybdates inside and covered by ⁱPrS^- and PhCOO^- ligands on the surfaces. Amazingly, the [Mo₈O₂₈@Ag₅₀] can be transformed from [Mo₆O₂₂@Ag₄₄] by adding PhCOOH which increases the degree of condensation of molybdates template from Mo₆O₂₂^8- to Mo₈O₂₈^8-, then enlarging the outer silver shell from Ag₄₄ to Ag₅₀. The evolution of solution species revealed by time-dependent electrospray ionization mass spectrometry (ESI-MS) suggests a breakage-growth-reassembly (BGR) transformation mechanism. These results not only provide a combined assembly strategy (anion-template + induced transformation) for the synthesis of silver-thiolate clusters but also help us to better understand the complex transformation process underpinning the assembly system.

Trapping an octahedral Ag6 kernel in a seven-fold symmetric Ag56 nanowheel

High-nuclearity silver clusters are appealing synthetic targets for their remarkable structures, but most are isolated serendipitously. We report here six giant silver-thiolate clusters mediated by solvents, which not only dictate the formation of an octahedral Ag₆⁴⁺ kernel, but also influence the in situ-generated Mo-based anion templates. The typical sevenfold symmetric silver nanowheels show a hierarchical cluster-in-cluster structure that comprises an outermost Ag₅₆ shell and an inner Ag₆⁴⁺ kernel in the centre with seven MoO₄^2- anion templates around it. Electrospray ionization mass spectrometry analyses reveal the underlying rule for the formation of such unique silver nanowheels. This work establishes a solvent-intervention approach to construct high-nuclearity silver clusters in which both the formation of octahedral Ag₆⁴⁺ kernel and in situ generation of various Mo-based anion templates can be simultaneously controlled.

A giant 90-nucleus silver cluster templated by hetero-anions

A giant 90-nucleus silver cluster templated by hetero-anions was isolated and characterized.

Johnson Solids: Anion-Templated Silver Thiolate Clusters Capped by Sulfonate

Sulfonates were incorporated into six novel high-nuclearity silver(I) thiolate clusters under the guidance of anion templates varied from S^2- , SO₄^2- , α-[Mo₅ O₁₈ ]^6- , β-[Mo₅ O₁₈ ]^6- , [Mo₂ O₈ ]^4- , to [Mo₄ O₁₄ (SO₄ )]^6- . Single crystal X-ray analysis revealed that SD/Ag1, SD/Ag3, SD/Ag5, and SD/Ag6 are discrete [S@Ag₆₀ ], [α-Mo₅ O₁₈ @Ag₃₆ ], [Mo₂ O₈ @Ag₃₀ ]₂ , and [Mo₄ O₁₄ (SO₄ )@Ag₇₃ ] clusters, respectively, whereas SD/Ag2 and SD/Ag4 are one-dimensional (1D) chains based on the [SO₄ @Ag₂₀ ] and [β-Mo₅ O₁₈ @Ag₃₆ ] cluster subunits, respectively. Their silver skeletons are protected exteriorly by thiolates and sulfonates and interiorly supported by diverse anions as templates. Structurally, cluster SD/Ag1 is a typical core-shell structure comprised of an inner Ag₁₂ cuboctahedron and an outer Ag₄₈ shell. The sulfate-templated drum-like Ag₂₀ cluster subunits are bridged by PhSO₃^- to give a 1D chain of SD/Ag2. Complex SD/Ag3 and SD/Ag4 are spindle-like Ag₃₆ clusters with isomeric [Mo₅ O₁₈ ]^6- inside, and the latter is further extended to a 1D chain through PhSO₃^- bridges. A pair of [Mo₂ O₈ ]^4- templated gourd-like Ag₃₀ clusters are dimerized in a head-to-head fashion to form SD/Ag5. Complex SD/Ag6 is the largest cluster in this family and doubly templated by unprecedented [Mo₄ O₁₄ (SO₄ )]^6- anions. Geometrically, the silver shells of SD/Ag1-SD/Ag5 show the polyhedral features of Johnson solids, instead of the usual Platonic or Archimedean solids. Solution behaviors and luminescent properties were also investigated in detail.

A Water-Stable Cl@Ag14 Cluster Based Metal-Organic Open Framework for Dichromate Trapping and Bacterial Inhibition

Decoding the principles of cluster-based framework assembly at the molecular level remains a persistent challenge. Herein, we isolated and characterized a novel water-stable three-dimensional (3D) metal-organic open framework [Cl@Ag₁₄(cPrC≡C)₁₀Cl₂·(p-TOS)·1/3H₂O]_n (SD/Ag14, cPrC≡CH = cyclopropylacetylene; p-TOS = p-toluenesulfonate), which contains a chloride-templated Ag₁₄ cluster as building block. For SD/Ag14, one chloride acts as the template to shape the Ag₁₄ cluster and the other bridges the clusters to a 3D pcu-h open framework. As revealed by high resolution electrospray mass spectrometry (HRESI-MS), the Ag₁₂-Ag₁₄ species are potential cluster-based intermediates to the 3D pcu-h framework, which authenticates a preconceived idea that the 3D framework is hierarchically assembled from the silver clusters as observed in solid state. Interestingly, SD/Ag14 can be used effectively to remove the environmental pollutant Cr₂O₇^2- from wastewater through anion exchange in a single-crystal-to-single-crystal (SC-SC) transformation fashion. Furthermore, SD/Ag14 exhibits excellent antibacterial activity against Staphylococcus aureus, thus making it a potential antibacterial agent.

Structure, solution assembly, and electroconductivity of nanosized argento-organic-cluster/framework templated by chromate

In view of elucidating potential structures and assembly mechanism of silver clusters and silver cluster-based metal-organic frameworks, we prepared four argento-organic-clusters/frameworks where the structures were directed by chromate in the presence of different thiolates. All four structures with ^tBuC₆H₄S^-, SⁱBu^-, and SⁱPr^- consist of three core-shells, an inner CrO₄^2-, an intermediate Ag-S aggregate and finally the protective organic moieties. {(HNEt₃)₃[Ag(CrO₄)₄@Ag₄₆(SC₆H₄^tBu)₂₄(CF₃COO)₁₈(DMF)₄]} (1) is a supertetrahedron with an inner Ag(CrO₄)₄ tetrahedron shelled by four fused Ag_11.5S₆ lobes. [(CrO₄)₅@Ag₄₀(SⁱBu)₂₇(CF₃COO)₃]_n (2) is an undulated snake-like tube housing the infinite CrO₄^2- tetrahedra. [(CrO₄)₂@Ag₄₁(SⁱBu)₃₀(NO₃)₃(CN)₄]_n (3) forms an uncommon 7-connected kwh network incorporating hexagonal layers of Ag₁₉(SⁱBu)₁₅ balls with a single inner CrO₄^2- connected by another Ag atom. Both enantiomeric chiral qtz frameworks of [CrO₄@Ag₂₀(SⁱPr)₁₀(Cr₂O₇)₂(COOCF₃)₄(DMF)₄]_n (4) were structurally characterized. In 4, Cr₂O₇^2- connects the Ag₂₀(SⁱPr)₁₀ clusters with a trapped CrO₄^2- into a 3D quartz (qtz) structure, where the spherical cluster acts like oxygen and Cr₂O₇^2- takes the place of Si in SiO₂. Electrospray ionization mass spectrometry (ESI-MS) analysis of the reaction solutions of 1-4 clearly indicated that (i) the Ag(CrO₄)₄@Ag₄₆ core of 1 can retain its molecular structure in the solution and (ii) the chromate-templated polynuclear silver-thiolate species in solution are important building blocks to construct the 1D or 3D motif for 2-4. The electrochemistry in sulfuric acid and enhancement of the electrical conductivity upon I₂ doping have also been reported.

Anion-templated nanosized silver clusters protected by mixed thiolate and diphosphine

S^2-, MoO₄^2-, and Mo₆O₂₂^8- were successfully employed as templates in the formation of six high-symmetry polynuclear silver clusters as exemplified in the single-crystal X-ray structures of [S@Ag₁₈(^tBuC₆H₄S)₁₆(dppp)₄]·DMF·5CH₃CN·3CH₃OH (1), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppm)₆(MoO₄)₄]·2BF₄·C₂H₅NO (2), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppm)₆(MoO₄)₄]·2CF₃SO₃ (3), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppf)₆(MoO₄)₄]·2CF₃SO₃ (4), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppb)₆(MoO₄)₄]·2CF₃SO₃ (5) and [Mo₆O₂₂@Ag₄₆(^tBuC₆H₄S)₃₂(dppm)₄(CH₃CN)₈]·6CF₃SO₃ (6) (dppp = 1,3-bis(diphenylphosphino)propane, dppm = bis(diphenylphosphino)methane, dppf = 1,1'-bis(diphenylphosphino)ferrocene and dppb = 1,4-bis(diphenylphosphino)butane). Cluster 1 is a S^2--centered octadecanuclear banana-shaped molecule. Clusters 2-5 have similar structures consisting of a tetrahedron of a MoO₄^2- core and four MoO₄^2- where three silver atoms cap each face and a pair sits on each edge, giving tetraicosanuclear ball-shaped molecules. Although different diphosphine ligands and silver salts were used in the syntheses, 2-5 contain a common building cluster unit with similar geometry and nuclearity. With (Bu₄N)₂Mo₆O₁₉ as a template, a giant 46-silver-atom cluster encapsulates an in situ modified Mo₆O₂₂^8- unit. The nuclearity and geometry depend on the size and shape of the templates. High-resolution electrospray mass spectrometry (HR-ESI-MS) analyses of 4 indicate its exceptionally high stability in acetonitrile. The solid-state luminescence of 1 as a function of the temperature exhibits thermochromism from red to yellow due to the different intensities of the two bands. This work established a new strategy for the construction of polynuclear silver clusters using an anionic template and mixed S- and P-donor ligands where a promising approach for building novel dual emissive materials is unraveled.

Unusual reactivity of dithiol protected clusters in comparison to monothiol protected clusters: studies using Ag51(BDT)19(TPP)3 and Ag29(BDT)12(TPP)4

We report the synthesis and unique reactivity of a new green dithiol protected cluster (DTPC), Ag₅₁(BDT)₁₉(TPP)₃ (BDT and TPP are 1,3-benzenedithiol and triphenylphosphine, respectively). The cluster composition was confirmed by electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometric studies as well as by other supporting data. Surprisingly, the chemical reactivity between this DTPC and Au₂₅(SR)₁₈ involves only metal ion exchange in Au₂₅(SR)₁₈ without any ligand exchange, while reactions between monothiol protected clusters (MTPCs) show both metal and ligand exchange, an example being the reaction between Ag₂₅DMBT₁₈ and Au₂₅PET₁₈ (where DMBT and PET are 2,4-dimethylbenzenethiol and phenylethanethiol, respectively). The conclusions have been confirmed by the reaction of another DTPC, Ag₂₉(BDT)₁₂(TPP)₄ with Au₂₅BT₁₈ (where BT corresponds to butanethiol) in which only metal exchange happens in Au₂₅BT₁₈. We also show the conversion of Ag₅₁(BDT)₁₉(TPP)₃ to Ag₂₉(BDT)₁₂(TPP)₄ in the presence of a second monothiol, DMBT which does not get integrated into the product cluster. This is completely different from the previous understanding wherein the reaction between MTPCs and a second thiol leads to either mixed thiol protected clusters with the same core composition or a completely new cluster core protected with the second thiol. The present study exposes a new avenue of research for monolayer protected clusters, which in turn will give additional impetus to explore the chemistry of DTPCs.

On rhenium(i)–silver(i) cyanide porous macrocyclic clusters

The first cyanide rhenium(i)–silver(i) clusters were synthesized in the course of simple one-pot high-yielding reactions.