Bulky Surface Ligands Promote Surface Reactivities of [Ag141X12(S-Adm)40]3+ (X = Cl, Br, I) Nanoclusters: Models for Multiple-Twinned Nanoparticles

Hierarchical Assembly of High-Nuclearity Copper(I) Alkynide Nanoclusters: Highly Effective CO2 Electroreduction Catalyst toward Hydrocarbons

The pursuit of precision in the engineering of metal nanoparticle assemblies has long fascinated scientists, but achieving atomic-level accuracy continues to pose a significant challenge. This research sheds light on the hierarchical assembly processes of two high-nuclearity Cu(I) nanoclusters (NCs). By employing a multiligand cooperative stabilization strategy, we have isolated a series of thiacalix[4]arene (TC4A)/alkynyl coprotected Cu(I) NCs (Cux, where x = 9, 13, 17, 22). These NCs are intricately coassembled from the fundamental building units of {Cu4(TC4A)} and alkynyl-stabilized Cu5L6 in various ratios. By capturing active anion templates such as O2-, Cl-, or C22- that are generated in situ, we have further explored the secondary structural self-assembly of these clusters. Cu13 serves as a secondary assembly module for constructing Cu38 and Cu43, which exhibit the highest nuclearity reported to date among Cu(I) NCs encased in macrocyclic ligands. Notably, Cu38 demonstrates an impressive Faradaic efficiency of 62.01% for hydrocarbons at -1.57 V vs RHE during CO2 electroreduction, with 34.03% for C2H4 and 27.98% for CH4. This performance establishes it as an exceptionally rare, large, atomically precise metal NC (nuclearity >30) capable of catalyzing the formation of highly electro-reduced hydrocarbon products. Our research has introduced a new approach for constructing high-nuclearity Cu(I) NCs through a hierarchical assembly method and investigating their potential in the electrocatalytic transformation of CO2 into hydrocarbons.

Silvery fullerene in Ag102 nanosaucer

Despite the discovery of a series of fullerenes and a handful of noncarbon clusters with the typical topology of I h-C60, the smallest fullerene with a large degree of curvature, C20, and its other-element counterparts are difficult to isolate experimentally. In coinage metal nanoclusters (NCs), the first all-gold fullerene, Au32, was discovered after a long-lasting pursuit, but the isolation of similar silvery fullerene structures is still challenging. Herein, we report a flying saucer-shaped 102-nuclei silver NC (Ag102) with a silvery fullerene kernel of Ag32, which is embraced by a robust cyclic anionic passivation layer of (KPO4)10. This Ag32 kernel can be viewed as a non-centered icosahedron Ag12 encaged into a dodecahedron Ag20, forming the silvery fullerene of Ag12@Ag20. The anionic layer (KPO4)10 is located at the interlayer between the Ag32 kernel and Ag70 shell, passivating the Ag32 silvery fullerene and templating the Ag70 shell. The t BuPhS- and CF3COO- ligands on the silver shell show a regioselective arrangement with the 60 t BuPhS- ligands as expanders covering the upper and lower of the flying saucer and 10 CF3COO- as terminators neatly encircling the edges of the structure. In addition, Ag102 shows excellent photothermal conversion efficiency (η) from the visible to near-infrared region (η = 67.1% ± 0.9% at 450 nm, 60.9% ± 0.9% at 660 nm and 50.2% ± 0.5% at 808 nm), rendering it a promising material for photothermal converters and potential application in remote laser ignition. This work not only captures silver kernels with the topology of the smallest fullerene C20, but also provides a pathway for incorporating alkali metal (M) into coinage metal NCs via M-oxoanions.

Construction of novel Ag(0)-containing silver nanoclusters by regulating auxiliary phosphine ligands

Controlled synthesis of metal clusters through minor changes in surface ligands holds significant interest because the corresponding entities serve as ideal models for investigating the ligand environment's stereochemical and electronic contributions that impact the corresponding structures and properties of metal clusters. In this work, we obtained two Ag(0)-containing nanoclusters (Ag17 and Ag32) with near-infrared emissions by regulating phosphine auxiliary ligands. Ag17 and Ag32 bear similar shells wherein Ag17 features a trigonal bipyramid Ag5 kernel while Ag32 has a bi-icosahedral interpenetrating an Ag20 kernel. Ag17 and Ag32 showed a near-infrared emission (NIR) of around 830 nm. Benefiting from the rigid structure, Ag17 displayed a more intense near-infrared emission than Ag32. This work provides new insight into the construction of novel superatomic silver nanoclusters by regulating phosphine ligands.

Experimental High-Resolution Observation of the Truncated Double-Icosahedron Structure: A Stable Twinned Shell in Alloyed Au-Ag Core@Shell Nanoparticles

Given the binary nature of nanoalloy systems, their properties are dependent on their size, shape, structure, composition, and chemical ordering. When energy and entropic factors for shapes and structure variations are considered in nanoparticle growth, the spectra of shapes become so vast that even metastable arrangements have been reported under ambient conditions. Experimental and theoretical variations of multiply twinned particles have been observed, from the Ino and Marks decahedra to polyicosahedra and polydecahedra with comparable energetic stability among them. Herein, we report the experimental production of a stable doubly truncated double-icosahedron structure (TdIh) in Au-Ag nanoparticles, in which a twinned Ag-rich alloyed shell is reconstructed on a Au-Ag alloyed Ino-decahedral core. The structure, chemical composition, and growth pathway are proposed on the basis of high-angle annular dark-field scanning transmission electron microscopy analysis and excess energy calculations, while its structural stability is estimated by large-scale atomic molecular dynamics simulations. This novel nanostructure differs from other structures previously reported.

Bottom-Up Construction of Metal-Organic Framework Loricae on Metal Nanoclusters with Consecutive Single Nonmetal Atom Tuning for Tailored Catalysis

The introduction of single or multiple heterometal atoms into metal nanoparticles is a well-known strategy for altering their structures (compositions) and properties. However, surface single nonmetal atom doping is challenging and rarely reported. For the first time, we have developed synthetic methods, realizing "surgery"-like, successive surface single nonmetal atom doping, replacement, and addition for ultrasmall metal nanoparticles (metal nanoclusters, NCs), and successfully synthesized and characterized three novel bcc metal NCs Au38I(S-Adm)19, Au38S(S-Adm)20, and Au38IS(S-Adm)19 (S-Adm: 1-adamantanethiolate). The influences of single nonmetal atom replacement and addition on the NC structure and optical properties (including absorption and photoluminescence) were carefully investigated, providing insights into the structure (composition)-property correlation. Furthermore, a bottom-up method was employed to construct a metal-organic framework (MOF) on the NC surface, which did not essentially alter the metal NC structure but led to the partial release of surface ligands and stimulated metal NC activity for catalyzing p-nitrophenol reduction. Furthermore, surface MOF construction enhanced NC stability and water solubility, providing another dimension for tunning NC catalytic activity by modifying MOF functional groups.

Thiacalix[4]arene Etching of an Anisotropic Cu70H22 Intermediate for Accessing Robust Modularly Assembled Copper Nanoclusters

Atom-precise metal nanoclusters (NCs) with large bulk (nuclearity >60) are important species for insight into the embryonic phase of metal nanoparticles and their top-down etching synthesis. Herein, we report a metastable rod-shaped 70-nuclei copper-hydride NC, [Cl@Cu70H22(PhC≡C)29(CF3COO)16]2+ (Cu70), with Cl- as the template, in which the Cl@Cu59 kernel adopts a distinctive metal packing mode along the bipolar direction, and the protective ligand shell exhibits corresponding site differentiation. In terms of metal nuclearity, Cu70 is the largest alkynyl-stabilized Cu-hydride cluster to date. As a typical highly active intermediate, Cu70 could undergo a transformation into a series of robust modularly assembled Cu clusters (B-type Cu8, A-A-type Cu22, A-B-type Cu23, and A-B-A-type Cu38) upon etching by p-tert-butylthiacalix[4]arene (H4TC4A), which could not be achieved by "one-pot" synthetic methods. Notably, the patterns of A and B blocks in the Cu NCs could be effectively modulated by employing appropriate counterions and blockers, and the modular assembly mechanism was illustrated through comprehensive solution chemistry analysis using HR-ESI-MS. Furthermore, catalytic investigations reveal that Cu38 could serve as a highly efficient catalyst for the cycloaddition of propargylic amines with CO2 under mild conditions. This work not only enriched the family of high-nuclear copper-hydride NCs but also provided new insights into the growth mechanism of metal NCs.

Effects of bromine-containing counterion salts in directing the structures of medium-sized silver nanoclusters

The preparation and structural determination of silver nanoclusters (especially the medium-sized Ag clusters) remain more challenging relative to those of their gold counterparts because of the comparative instability of the former. In this work, three medium-sized Ag clusters were controllably synthesized and structurally determined, namely, [Ag52(S-Adm)30Br4H20]2- (Ag52 for short), Ag54(S-Adm)30Br4H20 (Ag54 for short), and [Ag58(S-Adm)30Br4(NO3)2H22]2+ (Ag58 for short) nanoclusters. Specifically, the introduction of PPh4Br gave rise to the generation of Ag52 and Ag54 nanoclusters with homologous compositions and configurations, while the TOABr salt selected Ag58 as the sole cluster product, whose geometric structure was completely different from those of Ag52 and Ag54 nanoclusters. In addition, the optical absorptions and emissions of the three medium-sized silver nanoclusters were compared. The findings in this work not only provide three uniquely medium-sized nanoclusters to enrich the silver cluster family but also point out a new approach (i.e., changing the counterion salt) for the preparation of new nanoclusters with novel structures.

Thiacalix[4]arene-Protected Silver Nanoclusters Encapsulating Different Two-Electron Superatom Oligomers

The subvalent silver kernel represents the nascent state of silver cluster formation, yet the growth mechanism has long been elusive. Herein, two silver nanoclusters (Ag30 and Ag34) coprotected by TC4A4- (H4TC4A = p-tert-butylthiacalix[4]arene) and TBPMT- (TBPMTH = 4-tert-butylbenzenemethanethiol) containing 6e and 4e silver kernels are synthesized and characterized. The trimer of the 2e superatom Ag14 kernel in Ag30 is built from a central Ag6 octahedron sandwiched by two orthogonally oriented Ag5 trigonal bipyramids through sharing vertexes, whereas a double-octahedral Ag10 kernel in Ag34 is a dimer of 2e superatoms. They manifest disparate polyhedron fusion growth patterns at the beginning of the silver cluster formation. Their excellent solution stabilities are contributed by the multisite and multidentate coordination fashion of TC4A4- and the special valence electron structures. This work demonstrates the precise control of silver kernel growth by the solvent strategy and lays a foundation for silver nanocluster application in photothermal conversion.

Sandwich-Kernelled AgCu Nanoclusters with Golden Ratio Geometry and Promising Photothermal Efficiency

Metal nanoclusters have recently attracted extensive interest from the scientific community. However, unlike carbon-based materials and metal nanocrystals, they rarely exhibit a sheet kernel structure, probably owing to the instability caused by the high exposure of metal atoms (particularly in the relatively less noble Ag or Cu nanoclusters) in such a structure. Herein, we synthesized a novel AgCu nanocluster with a sandwich-like kernel (diameter≈0.9 nm and length≈0.25 nm) by introducing the furfuryl mercaptan ligand (FUR) and the alloying strategy. Interestingly, the kernel consists of a centered silver atom and two planar Ag10 pentacle units with completely mirrored symmetry after a rotation of 36 degrees. The two Ag10 pentacles and some extended structures show an unreported golden ratio geometry, and the two inner five-membered rings and the centered Ag atom form an unanticipated full-metal ferrocene-like structure. The featured kernel structure causes the dominant radial direction transition of excitation electrons, as determined via time-dependent density functional theory calculations, which affords the protruding absorption at 612 nm and contributes to the promising photothermal conversion efficiency of 67.6 % of the as-obtained nanocluster, having important implications for structure-property correlation and the development of nanocluser-based photothermal materials.

Anion-templated silver nanoclusters: precise synthesis and geometric structure

Metal nanoclusters (NCs) are gaining much attention in nanoscale materials research because they exhibit size-specific physicochemical properties that are not observed in the corresponding bulk metals. Among them, silver (Ag) NCs can be precisely synthesized not only as pure Ag NCs but also as anion-templated Ag NCs. For anion-templated Ag NCs, we can expect the following capabilities: 1) size and shape control by regulating the central anion (anion template); 2) stabilization by adjusting the charge interaction between the central anion and surrounding Ag atoms; and 3) functionalization by selecting the type of central anion. In this review, we summarize the synthesis methods and influences of the central anion on the geometric structure of anion-templated Ag NCs, which include halide ions, chalcogenide ions, oxoanions, polyoxometalate, or hydride/deuteride as the central anion. This summary provides a reference for the current state of anion-templated Ag NCs, which may promote the development of anion-templated Ag NCs with novel geometric structures and physicochemical properties.

Solvent-mediated precipitating synthesis and optical properties of polyhydrido Cu13 nanoclusters with four vertex-sharing tetrahedrons

Structurally defined metal nanoclusters facilitate mechanism studies and promote functional applications. However, precisely constructing copper nanoclusters remains a long-standing challenge in nanoscience. Developing new efficient synthetic strategies for Cu nanoclusters is highly desirable. Here, we propose a solvent-mediated precipitating synthesis (SMPS) to prepare Cu13H10(SR)3(PPh3)7 nanoclusters (H-SR = 2-chloro-4-fluorobenzenethiol). The obtained Cu13 nanoclusters are high purity and high yield (39.5%, based on Cu atom), proving the superiority of the SMPS method. The Cu13 nanoclusters were comprehensively studied via a series of characterizations. Single crystal X-ray crystallography shows that the Cu13 nanoclusters contain a threefold symmetry axis and the Cu13 kernel is protected by a monolayer of ligands, including PPh3 and thiolates. Unprecedentedly, the aesthetic Cu13 kernel is composed of four vertex-sharing tetrahedrons, rather than the common icosahedral or cuboctahedral M13. The intramolecular π⋯π interactions between thiolates and PPh3 on the surface contribute to the stable configuration. Furthermore, electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) revealed the existence of ten hydrides, including four types of hydrides. Density functional theory (DFT) calculations without simplifying the ligands simulated the location of the 10 hydrides in the crystal structure. Additionally, the steady-state ultraviolet-visible absorption and fluorescence spectra of the Cu13 nanoclusters exhibit unique optical absorbance and photoluminescence. The ultrafast relaxation dynamics were also studied via transient absorption spectroscopy, and the three decay components are attributed to the relaxation pathways of internal conversion, structural relaxation and radiative relaxation. This work provides not only a novel SMPS strategy to efficiently synthesize Cu13 nanoclusters, but also a better insight into the structural characteristics and optical properties of the Cu nanoclusters.

DFT Insights into the Variety in the Coordination Modes of the Equatorial Halides in [Au13 Ag12 (PR3 )10 X8 ]+ (X=Cl/Br) Clusters

The bonding character within metal nanoclusters represents an intriguing topic, shedding light on the inherent driving force for the packing preference in nanomaterials. Herein, density functional theory (DFT) calculations were conducted to investigate the correlation of the series of isomeric [Au₁₃ Ag₁₂ (PR₃ )₁₀ X₈ ]⁺ (X=Cl/Br) clusters, which are mainly differentiated by the coordination mode of the equatorial halides (μ₂ -, μ₃ - and μ₄ -) in the rod-like, bi-icosahedral framework. The theoretical simulation corroborates the variety in the configuration of the Au₁₃ Ag₁₂ clusters and elucidates the fast isomerization kinetics among the different configurations. The easy tautomerization and the variety in chloride binding modes correspond to a fluxionality character of the equatorial halides and are verified by the potential energy curve analysis. The structural flexibility of the central Au₃ Ag₁₀ block is the main driving force, while the relatively stronger Ag-X bonding interaction (compared to that of Au-X), and a sufficient number of halides are also requisite for the associating Ag-X tautomerizations.

Surface and Interface Coordination Chemistry Learned from Model Heterogeneous Metal Nanocatalysts: From Atomically Dispersed Catalysts to Atomically Precise Clusters

The surface and interface coordination structures of heterogeneous metal catalysts are crucial to their catalytic performance. However, the complicated surface and interface structures of heterogeneous catalysts make it challenging to identify the molecular-level structure of their active sites and thus precisely control their performance. To address this challenge, atomically dispersed metal catalysts (ADMCs) and ligand-protected atomically precise metal clusters (APMCs) have been emerging as two important classes of model heterogeneous catalysts in recent years, helping to build bridge between homogeneous and heterogeneous catalysis. This review illustrates how the surface and interface coordination chemistry of these two types of model catalysts determines the catalytic performance from multiple dimensions. The section of ADMCs starts with the local coordination structure of metal sites at the metal-support interface, and then focuses on the effects of coordinating atoms, including their basicity and hardness/softness. Studies are also summarized to discuss the cooperativity achieved by dual metal sites and remote effects. In the section of APMCs, the roles of surface ligands and supports in determining the catalytic activity, selectivity, and stability of APMCs are illustrated. Finally, some personal perspectives on the further development of surface coordination and interface chemistry for model heterogeneous metal catalysts are presented.

Insights into mechanisms of diphosphine-mediated controlled surface construction on Au nanoclusters

Unraveling the rules governing the size regulation of nanoclusters is of great importance not only in fundamental research, but also in practical applications because of the high structure-property correlation in nanoclusters. Diphosphine-mediated size tailoring is recognized as a powerful method for modulating the size, configuration, and properties of nanoclusters, but the role of diphosphines in these size-controlled processes is still poorly understood due to a lack of systematic studies. Herein, using Au₂₃(SR)₁₆^- as the template for modification, the factors influencing the size-modulation of nanoclusters by diphosphines were systematically investigated. It is revealed that by controlling the length of the diphosphines (from shorter to longer), Au₂₁(SR)₁₂L₂⁺ (L = diphosphine) and Au₂₂(SR)₁₄L can be produced. Moreover, introducing a rigid group into the diphosphines can twist the structural framework or lead to the formation of a new surface motif configuration in the nanoclusters, forming twisted Au₂₂(SR)₁₄L and Au₂₅(SR)₁₆L₂⁺. The size regulation of these nanoclusters enables fine-tuning of the optical properties, including the absorption wavelengths and photoluminescence emission intensity, affording an avenue for precise control of the physicochemical properties of nanoclusters for practical applications.

Conductance Growth of Single-Cluster Junctions with Increasing Sizes

Quantum-tunneling-based nanoelectronics has the potential for the miniaturization of electronics toward the sub-5 nm scale. However, the nature of phase-coherent quantum tunneling leads to the rapid decays of the electrical conductance with tunneling transport distance, especially in organic molecule-based nanodevices. In this work, we investigated the conductance of the single-cluster junctions of a series of atomically well-defined silver nanoclusters, with varying sizes from 0.9 to 3.0 nm, using the mechanically controllable break junction (MCBJ) technique combined with quantum transport theory. Our charge transport investigations of these single-cluster junctions revealed that the conductance grows with increasing cluster size. The conductance decay constant was determined to be ∼-0.4 nm^-1, which is of opposite sign to that of organic molecules. Comparison between experiment and theory reveals that although charge transport through the silver single-cluster junctions occurs via phase-coherent tunneling, this is compensated by a rapid decrease in the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO gap) with size and the increase in the electrode-cluster coupling, which results in their conductance increase up to lengths of ∼3.0 nm. These results demonstrate that such families of nanoclusters provide unique bottom-up building blocks for the fabrication of nanodevices in the sub-5 nm size range.

An atomically precise silver nanocluster for artificial light-harvesting system through supramolecular functionalization

Designing an artificial light-harvesting system (LHS) with high energy transfer efficiency has been a challenging task. Herein, we report an atom-precise silver nanocluster (Ag NC) as a unique platform to fabricate the artificial LHS. A facile one-pot synthesis of [Cl@Ag16S(S-Adm)8(CF3COO)5(DMF)3(H2O)2]·DMF (Ag16) NC by using a bulky adamantanethiolate ligand is portrayed here which, in turn, alleviates the issues related to the smaller NC core designed from a highly steric environment. The surface molecular motion of this NC extends the non-radiative relaxation rate which is strategically restricted by a recognition site-specific supramolecular adduct with β-cyclodextrin (β-CD) that results in the generation of a blue emission. This emission property is further controlled by the number of attached β-CD which eventually imposes more rigidity. The higher emission quantum yield and the larger emission lifetime relative to the lesser numbered β-CD conjugation signify Ag16 ∩ β-CD2 as a good LHS donor component. In the presence of an organic dye (β-carotene) as an energy acceptor, an LHS is fabricated here via the Förster resonance energy transfer pathway. The opposite charges on the surfaces and the matched electronic energy distribution result in a 93% energy transfer efficiency with a great antenna effect from the UV-to-visible region. Finally, the harvested energy is utilized successfully for efficient photocurrent generation with much-enhanced yields compared to the individual components. This fundamental investigation into highly-efficient energy transfer through atom-precise NC-based systems will inspire additional opportunities for designing new LHSs in the near future.

[Cu18H3(S-Adm)12(PPh3)4Cl2]: fusion of Platonic and Johnson solids through a Cu(0) center and its photophysical properties

Structural elucidation of atom-precise thiolate-protected copper nanoclusters (Cu NCs) containing Cu(0) is quite challenging. Here, we report a new adamantane-thiol-protected NC, [Cu18H3(S-Adm)12(PPh3)4Cl2] (Cu18), which represents the first observation of a rare mononuclear Cu(0)-containing Cu10H3Cl2 core that is constructed via kernel fusion through vertex sharing of the Platonic-solid- and Johnson-solid-geometry-like kernels and hydride-bridging. The unique core is surrounded by a Cu8S12P4 metal-ligand motif shell and adopts a butterfly-like structure. In comparison to its closest structural analogue, the predominant effect of the principal Cu atom vacancy-induced structural rearrangement is evidenced. The occupied orbitals of this NC have a major d-orbital contribution to the distorted Cu6 octahedral kernel, whereas unoccupied orbitals owe a contribution to the distorted Cu5 square-pyramidal kernel. Thus, the charge transfer phenomenon is uniquely instigated between the two fused kernels through Cu(d) → Cu(d) transition via the Cu(0) center. This NC exhibits violet emission due to kernel-dominated relaxation at room temperature, which is further enhanced by confining the surface protecting ligands through recognition-site-specific host-guest supramolecular adduct formation by β-cyclodextrin. The unique electronic structure of this NC further facilitates its application toward photocurrent generation. Thus, this study offers a unique strategy for the controllable synthesis of a Cu(0)-containing Cu NC, which enables atomic-level insights into their optoelectronic properties.

Silver nanoclusters show advantages in macrophage tracing in vivo and modulation of anti-tumor immuno-microenvironment

Macrophage-based nanomedicine represents an emerging powerful strategy for cancer therapy. Unfortunately, some obstacles and challenges limit the translational applications of macrophage-mediated nanodrug delivery system. For instance, tracking and effective cell delivery for targeted tumor sites remain to be overcome, and controlling the states of macrophages is still rather difficult due to their plastic nature in response to external stimuli. To address these critical issues, here, we reported a novel type of silver nanoclusters (AgNCs) with excellent fluorescent intensity, especially long-lasting cell labeling stability after endocytosis by macrophages, indicating promising applications in tracking macrophage-based nanomedicine delivery. Our mechanistic investigations uncovered that these merits originate from the escape of AgNCs from lysosomal degradation within macrophages. In addition, the AgNCs would prime the M1-like polarization of macrophages (at least in part) through the toll-like receptor 4 signaling pathway. The engineered macrophages laden with AgNCs could be employed for lung metastasis breast cancer treatment, showing the effective targeting propensity to metastatic tumors, remarkable regulation of tumor immune microenvironment and inhibition of tumor growth. Collectively, AgNC-trained macrophages appear to be a promising strategy for tumor immune-microenvironment regulation, which might be generalized to a wider spectrum of cancer therapeutics.

The New Ag-S Cluster [Ag50S13(StBu)20][CF3COO]4 with a Unique hcp Ag14 Kernel and Ag36 Keplerian-Shell-Based Structural Architecture and Its Photoresponsivity

In metal nanoclusters (NCs), the kernel geometry and the nature of the surface protecting ligands are very crucial for their structural stability and properties. The synthesis and structural elucidation of Ag NCs is challenging because the zerovalent oxidation state of Ag is very reactive and prone to oxidization. Here, we report the NC [Ag₅₀S₁₃(S^tBu)₂₀][CF₃COO]₄ with a hexagonal close-packed (hcp) cagelike Ag₁₄ kernel. A truncated cubic shell and an octahedral shell encapsulate the hcp-layered kernel via an interstitial S^2- anionic shell to form an Ag₃₆ Keplerian outer shell of the NC. A theoretical study indicates the stability of this NC in its 4+ charge state and the charge distribution between the kernel and Keplerian shell. The unprecedented electronic structure facilitates its application toward sustainable photoresponse properties. The new insights into this novel Ag NC kernel and Keplerian shell structure may pave the way to understanding the unique structure and developing electronic structure-based applications.

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.

Emergent properties in supercrystals of atomically precise nanoclusters and colloidal nanocrystals

We provide a comprehensive account of the optical, electrical and mechanical properties that result from the self-assembly of colloidal nanocrystals or atomically precise nanoclusters into crystalline arrays with long-range order....

Chemical Insights into Interfacial Effects in Inorganic Nanomaterials

The interfaces between inorganic functional nanomaterials and their surface modifiers play important roles in determining their chemical and physical properties. In numerous situations, interfaces created by organic ligands or secondary inorganic components on inorganic nanomaterials induce significant effects to promote their performances. However, it still remains challenging to understand those interfacial effects at the molecular level. Herein, strategies via the design of model inorganic nanomaterials with well-defined and detectable interfaces to simplify the investigation of interfacial effects in inorganic nanomaterials are summarized. While atomically precise metal nanoclusters enable "seeing" how organic ligands are coordinated on metal surface to create nanoscale metal-organic interfaces, ultrathin low-dimensional nanomaterials modified with organic ligands make it possible to extract the metal-organic interface structure from the average signal to investigate how steric and electronic effects enhance catalysis. The molecular mechanisms of the interfacial effects in supported metal catalysts are disclosed by designing two unique structures of supported catalysts. The interfacial engineering approach will be further extended to optimize the performance and stability of perovskite solar cells. Finally, a perspective on the development of operando characterization techniques is provided to track the dynamic interfacial structures during catalysis.

Programmable Metal Nanoclusters with Atomic Precision

With the recent establishment of atomically precise nanochemistry, capabilities toward programmable control over the nanoparticle size and structure are being developed. Advances in the synthesis of atomically precise nanoclusters (NCs, 1-3 nm) have been made in recent years, and more importantly, their total structures (core plus ligands) have been mapped out by X-ray crystallography. These ultrasmall Au nanoparticles exhibit strong quantum-confinement effect, manifested in their optical absorption properties. With the advantage of atomic precision, gold-thiolate nanoclusters (Au_n (SR)_m ) are revealed to contain an inner kernel, Au-S interface (motifs), and surface ligand (-R) shell. Programming the atomic packing into various crystallographic structures of the metal kernel can be achieved, which plays a significant role in determining the optical properties and the energy gap (E_g ) of NCs. When the size increases, a general trend is observed for NCs with fcc or decahedral kernels, whereas those NCs with icosahedral kernels deviate from the general trend by showing comparably smaller E_g . Comparisons are also made to further demonstrate the more decisive role of the kernel structure over surface motifs based on isomeric Au NCs and NC series with evolving kernel or motif structures. Finally, future perspectives are discussed.

Light-Activated Intercluster Conversion of an Atomically Precise Silver Nanocluster

Noble metal nanoclusters protected with carboranes, a 12-vertex, nearly icosahedral boron-carbon framework system, have received immense attention due to their different physicochemical properties. We have synthesized ortho-carborane-1,2-dithiol (CBDT) and triphenylphosphine (TPP) coprotected [Ag₄₂(CBDT)₁₅(TPP)₄]^2- (shortly Ag₄₂) using a ligand-exchange induced structural transformation reaction starting from [Ag₁₈H₁₆(TPP)₁₀]²⁺ (shortly Ag₁₈). The formation of Ag₄₂ was confirmed using UV-vis absorption spectroscopy, mass spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and multinuclear magnetic resonance spectroscopy. Multiple UV-vis optical absorption features, which exhibit characteristic patterns, confirmed its molecular nature. Ag₄₂ is the highest nuclearity silver nanocluster protected with carboranes reported so far. Although these clusters are thermally stable up to 200 °C in their solid state, light-irradiation of its solutions in dichloromethane results in its structural conversion to [Ag₁₄(CBDT)₆(TPP)₆] (shortly Ag₁₄). Single crystal X-ray diffraction of Ag₁₄ exhibits Ag₈-Ag₆ core-shell structure of this nanocluster. Other spectroscopic and microscopic studies also confirm the formation of Ag₁₄. Time-dependent mass spectrometry revealed that this light-activated intercluster conversion went through two sets of intermediate clusters. The first set of intermediates, [Ag₃₇(CBDT)₁₂(TPP)₄]^3- and [Ag₃₅(CBDT)₈(TPP)₄]^2- were formed after 8 h of light irradiation, and the second set comprised of [Ag₃₀(CBDT)₈(TPP)₄]^2-, [Ag₂₆(CBDT)₁₁(TPP)₄]^2-, and [Ag₂₆(CBDT)₇(TPP)₇]^2- were formed after 16 h of irradiation. After 24 h, the conversion to Ag₁₄ was complete. Density functional theory calculations reveal that the kernel-centered excited state molecular orbitals of Ag₄₂ are responsible for light-activated transformation. Interestingly, Ag₄₂ showed near-infrared emission at 980 nm (1.26 eV) with a lifetime of >1.5 μs, indicating phosphorescence, while Ag₁₄ shows red luminescence at 626 nm (1.98 eV) with a lifetime of 550 ps, indicating fluorescence. Femtosecond and nanosecond transient absorption showed the transitions between their electronic energy levels and associated carrier dynamics. Formation of the stable excited states of Ag₄₂ is shown to be responsible for the core transformation.

[Ag71(S-tBu)31(Dppm)](SbF6)2: an intermediate-sized metalloid silver nanocluster containing a building block of Ag64

An intermediate-sized atomically precise metalloid silver nanocluster [Ag₇₁(SR)₃₁(Dppm)](SbF₆)₂ (Dppm = bis (diphenylphosphino)methane, SR = S-^tBu) is reported, which comprises one building block Ag₆₄, six SR₅ pentagons, one sole SR ligand, a DppmAg₂ handle, and an Ag₅ lid. Structurally, a decahedron Ag₂₃ kernel is observed in the metalloid silver nanocluster. Moreover, the Ag₆₄ unit provides insights into the growth of large clusters such as Ag₁₃₆(SR)₆₄Cl₃ and Ag₁₄₁(SR)₄₀Br₁₂via assembly. The observed decahedron Ag₂₃ provides a deeper understanding on Marks decahedron in larger nanoclusters, and the [Ag₇₁(S-^tBu)₃₁(Dppm)](SbF₆)₂ uses Ag₆₄ as a building block to predict the structure of larger metalloid nanoclusters.

Structure Determination of the Cl-Enriched [Ag52(SAdm)31Cl13]2+ Nanocluster

Cl atoms can serve as the innermost core, the peripheral ligand, or the counterions of metal nanoclusters. Herein, we report the structural determination a Cl-enriched [Ag₅₂(SAdm)₃₁Cl₁₃]²⁺. The ratio of Cl to AdmSH is quite high compared to those of other nanoclusters. Structurally, nine Cl atoms, existing at the interlayer of the inner kernel and the surface motif, serve as the bridging ligands to sustain the robustness of the whole structure. Interestingly, four Cl atoms on the motif structure can be substituted by Br. This work allows us to clear the regulation of Cl ligands in the structural construction of metal nanoclusters.

A Nanocluster [Ag307Cl62(SPhtBu)110]: Chloride Intercalation, Specific Electronic State, and Superstability

The controlling synthesis of novel nanoclusters of noble metals (Au, Ag) and the determination of their atomically precise structures provide opportunities for investigating their specific properties and applications. Here we report a novel silver nanocluster [Ag₃₀₇Cl₆₂(SPh^tBu)₁₁₀] (Ag₃₀₇) whose structure is determined by X-ray single crystal diffraction. The structure analysis shows that nanocluster Ag₃₀₇ contains a Ag₁₆₇ core, a surface shell of [Ag₁₄₀Cl₂S₁₁₀], and a Cl₆₀ intermediate layer located between Ag₁₆₇ and [Ag₁₄₀Cl₂S₁₁₀]. It is a first example that such many chlorides are intercalated into a Ag nanocluster. Chlorides are released in situ from solvent CHCl₃. Nanocluster Ag₃₀₇ exhibits superstability. Differential pulse voltammetry experiment reveals that Ag₃₀₇ has continuous charging/discharging behavior with a capacitance value of 1.39 aF, while the Ag₃₀₇ has a surface plasmonic feature. These characteristics show that Ag₃₀₇ is of metallic behavior. However, its electron paramagnetic resonance (EPR) spectra display a spin magnetic behavior which could be originated from the unpassivated dangling bonds of surface atoms. The direct capture of EPR signals can be attributed to the Cl^- intercalating layer which partly suppresses the electronic interactions between core and surface atoms, resulting in the relatively independent electronic states for core and surface atoms.

A Molecular Hybrid of an Atomically Precise Silver Nanocluster and Polyoxometalates for H2 Cleavage into Protons and Electrons

Atomically precise silver (Ag) nanoclusters are promising materials as catalysts, photocatalysts, and sensors because of their unique structures and mixed-valence states (Ag⁺ /Ag⁰ ). However, their low stability hinders the in-depth study of their intrinsic reactivity and catalytic property accompanying their redox processes. Herein, we demonstrate that a molecular hybrid of an atomically precise {Ag₂₇ }¹⁷⁺ nanocluster and polyoxometalates (POMs) can efficiently cleave H₂ into protons and electrons. The Ag nanocluster accommodates electrons through the redox reaction from {Ag₂₇ }¹⁷⁺ to {Ag₂₇ }¹³⁺ , and the POM ligands play the following important roles: (i) a significant stabilization of the typically unstable Ag nanocluster to preserve its structure during the redox reaction with H₂ , (ii) formation of a unique interface between the Ag nanocluster and metal oxides for efficient H₂ cleavage, and (iii) storage of the generated protons on the negatively charged basic surface.

Anisotropic Evolution of Nanoclusters from Ag40 to Ag45: Halogen- and Defect-Induced Epitaxial Growth in Nanoclusters

Halogens have widely served as handles for regulating the growth of nanoparticles and the control of their physicochemical properties. However, their regulatory mechanism is poorly understood. Nanoclusters are the early morphology of nanoparticles and play an important role in revealing the formation and growth of nanoparticles due to their precise structures. Here, we report that halogens induce the anisotropic growth of Ag₄₀(C₆H₅COO)₁₃(SR)₁₉(CH₃CN) (Ag₄₀-II, where SR = 4-tert-butylbenzylmercaptan) into Ag₄₅(C₆H₅COO)₁₃(SR)₂₂Cl₂ (Ag₄₅), where Ag₄₀-II is converted from Ag₄₀(CH₃COO)₁₀(SR)₂₂ (Ag₄₀-I). Experiments and theoretical simulations showed that halogen ions adsorb at both ends of the cluster, forming defect sites. The -SR-Ag- complexes fill the defects and complete the anisotropic transition from Ag₄₀-II to Ag₄₅. Circular dichroism spectra show that the chirality of Ag₄₅ decreases 15-fold compared with that of Ag₄₀-II. This work provides important insights into the effects of halogens on the growth mechanism and property regulation for nanomaterials at the atomic level and the benefits of further applications of halogen-induced nanomaterials.

Quantized doping of CdS quantum dots with twelve gold atoms

Through a bottom-up strategy, CdS quantum dots (QDs) doped with 12 gold atoms in each nanocrystal (NC) were prepared by cation exchange reactions. The (Au12) dopants inside the CdS matrix were directly observed using Cs-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images and quantitatively confirmed using the inductively coupled plasma atomic emission spectroscopy (ICP-AES) data. With a photoluminescence quantum yield (PLQY) of 37.5%, the as-prepared (Au12)@CdS QDs emitted light at 635 nm. Due to the injection of excited electrons from the lowest unoccupied molecular orbital (LUMO) of dopants to the conduction band (CB) of CdS, multiple fine peaks were observed in the photoluminescence excitation (PLE) spectra. By using clusters as starting materials, we demonstrate a universal approach for the precise tailoring of dopants and provide a pathway for band energy engineering of doped QDs.

Construction of Silver Clusters Capped by Zwitterionic Ethynide Ligands

A zwitterionic ligand 3-(triethylammonio)propyne (TAP) has been employed to construct nine silver ethynide compounds for the first time. Single-crystal X-ray analyses reveal that compounds 1 and 2 are silver ethynide assemblies based on the Ag₃ subunits and clusters 3-8 are small discrete clusters of Ag₃, Ag₆, Ag₈, and Ag₁₂, respectively, ligated by the bulky TAP ligand with different auxiliary ligands. In addition, upon acquiring the tripod-like ^tBuPO₃^2-, a unprecedented 80 nuclei silver ethynide cluster was isolated and determined to be [(CF₃CO₂)₅@Ag₈₀(TAP)₁₄(^tBuPO₃)₁₆(CF₃CO₂)₂₄]¹⁹⁺ by crystallography and thermogravimetric analysis. The C₁ symmetry of Ag₈₀ was deconstructed to be two [Ag₄₀(TAP)₇(^tBuPO₃)₈(CF₃CO₂)₁₂]¹²⁺ secondary building subunits arranged in a cross way, with five CF₃CO₂^- trapped in the center. These results highlight that the elaborate selection of ethynide ligands is of great importance in the synthesis of novel silver ethynide clusters.

Enhanced Surface Ligands Reactivity of Metal Clusters by Bulky Ligands for Controlling Optical and Chiral Properties

Surface ligands play critical roles in determining the surface properties of metal clusters. However, modulating the properties and controlling the surface structure of clusters through surface-capping-agent displacement is challenging. Herein, [Ag₁₄ (SPh(CF₃ )₂ )₁₂ (PPh₃ )₄ (DMF)₄ ] (Ag₁₄ -DMF; DMF=N,N-dimethylformamide), with weakly coordinated DMF ligands on surface silver sites, was synthesized by a mixed-ligands strategy. Owing to the high surface reactivity of Ag₁₄ -DMF, the surface ligands are labile, easily dissociated or exchanged by other ligands. Based on the enhanced surface reactivity, easy modulation of the optical properties of Ag₁₄ by reversible "on-off" DMF ligation was realized. When chiral amines were introduced to as-prepared products, all eight surface ligands were replaced by amines and the racemic Ag₁₄ clusters were converted to optically pure homochiral Ag₁₄ clusters as evidenced by circular dichroism (CD) activity and single-crystal X-ray diffraction (SCXRD). This work provides a new insight into modulation of the optical properties of metal clusters and atomically precise homochiral clusters for specific applications are obtained.

Ligand exchange reactions on thiolate-protected gold nanoclusters

As a versatile post-synthesis modification method, ligand exchange reaction exhibits great potential to extend the space of accessible nanoclusters. In this review, we summarized this process for thiolate-protected gold nanoclusters. In order to better understand this reaction we will first provide the necessary background on the synthesis and structure of various gold clusters, such as Au25(SR)18, Au38(SR)24, and Au102(SR)44. The previous investigations illustrated that ligand exchange is enabled by the chemical properties and flexible gold-sulfur interface of nanoclusters. It is generally believed that ligand exchange follows a SN2-like mechanism, which is supported both by experiments and calculations. More interesting, several studies show that ligand exchange takes place at preferred sites, i.e. thiolate groups -SR, on the ligand shell of nanoclusters. With the help of ligand exchange reactions many functionalities could be imparted to gold nanoclusters including the introduced of chirality to achiral nanoclusters, size transformation and phase transfer of nanoclusters, and the addition of fluorescence or biological labels. Ligand exchange was also used to amplify the enantiomeric excess of an intrinsically chiral cluster. Ligand exchange reaction accelerates the prosperity of the nanocluster field, and also extends the diversity of precise nanoclusters.

Insights into the Interfacial Effects in Heterogeneous Metal Nanocatalysts toward Selective Hydrogenation

Heterogeneous metal catalysts are distinguished by their structure inhomogeneity and complexity. The chameleonic nature of heterogeneous metal catalysts have prevented us from deeply understanding their catalytic mechanisms at the molecular level and thus developing industrial catalysts with perfect catalytic selectivity toward desired products. This Perspective aims to summarize recent research advances in deciphering complicated interfacial effects in heterogeneous hydrogenation metal nanocatalysts toward the design of practical heterogeneous catalysts with clear catalytic mechanism and thus nearly perfect selectivity. The molecular insights on how the three key components (i.e., catalytic metal, support, and ligand modifier) of a heterogeneous metal nanocatalyst induce effective interfaces determining the hydrogenation activity and selectivity are provided. The interfaces influence not only the H₂ activation pathway but also the interaction of substrates to be hydrogenated with catalytic metal surface and thus the hydrogen transfer process. As for alloy nanocatalysts, together with the electronic and geometric ensemble effects, spillover hydrogenation occurring on catalytically "inert" metal by utilizing hydrogen atom spillover from active metal is highlighted. The metal-support interface effects are then discussed with emphasis on the molecular involvement of ligands located at the metal-support interface as well as cationic species from the support in hydrogenation. The mechanisms of how organic modifiers, with the ability to induce both 3D steric and electronic effects, on metal nanocatalysts manipulate the hydrogenation pathways are demonstrated. A brief summary is finally provided together with a perspective on the development of enzyme-like heterogeneous hydrogenation metal catalysts.

Distinct structure assembly driven by metal-ligand binding in Au23 nanoclusters and its relation to photocatalysis

Here, we introduce two Au₂₃ nanoclusters to unveil the significance of metal-ligand binding-induced assembly. The Au₂₃ cluster protected by the thiolate ligand is packed in the shell-by-shell arrangement, while the Au₂₃ cluster capped by dual ligands of thiolate and PPh₃ is constructed from the assembly of Au₄ tetrahedra. Furthermore Au₂₃ from Au₄ tetrahedron-based assembly is capable of converting absorbed visible light into more excitons, compared to Au₂₃ from shell-by-shell assembly, thus exhibiting more efficient photocatalysis.

Nanocatalysts for High Selectivity Enyne Cyclization: Oxidative Surface Reorganization of Gold Sub-2-nm Nanoparticle Networks

Ultrasmall gold nanoparticles (NPs) stabilized in networks by polymantane ligands (diamondoids) were successfully used as precatalysts for highly selective heterogeneous gold-catalyzed dimethyl allyl(propargyl)malonate cyclization to 5-membered conjugated diene. Such reaction usually suffers from selectivity issues with homogeneous catalysts. This control over selectivity further opened the way to one-pot cascade reaction, as illustrated by the 1,6-enyne cycloisomerization-Diels-Alder reaction of dimethyl allyl propargyl malonate with maleic anhydride. The ability to assemble nanoparticles with controllable sizes and shapes within networks concerns research in sensors, medical diagnostics, information storage, and catalysis applications. Herein, the control of the synthesis of sub-2-nm gold NPs is achieved by the formation of dense networks, which are assembled in a single step reaction by employing ditopic polymantanethiols. By using 1,1'-bisadamantane-3,3'-dithiol (BAd-SH) and diamantane-4,9-dithiol (DAd-SH), serving both as bulky surface stabilizers and short-sized linkers, we provide a simple method to form uniformly small gold NPs (1.3 ± 0.2 nm to 1.6 ± 0.3 nm) embedded in rigid frameworks. These NP arrays are organized alongside short interparticular distances ranging from 1.9 to 2.7 nm. The analysis of gold NP surfaces and their modification were achieved in joint experimental and theoretical studies, using notably XPS, NMR, and DFT modeling. Our experimental studies and DFT analyses highlighted the necessary oxidative surface reorganization of individual nanoparticles for an effective enyne cycloisomerization. The modifications at bulky stabilizing ligands allow surface steric decongestion for the alkyne moiety activation but also result in network alteration by overoxidation of sulfurs. Thus, sub-2-nm nanoparticles originating from networks building create convenient conditions for generating reactive Au(I) surface single-sites-in the absence of silver additives-useful for heterogeneous gold-catalyzed enyne cyclization. These nanocatalysts, which as such ease organic products separation, also provide a convenient access for building further polycyclic complexity, owing to their high reactivity and selectivity.

Atomically Precise Alkynyl- and Halide-Protected AuAg Nanoclusters Au78Ag66(C≡CPh)48Cl8 and Au74Ag60(C≡CPh)40Br12: The Ligation Effects of Halides

Reported herein are the synthesis and structures of two high-nuclearity AuAg nanoclusters, namely, [Au₇₈Ag₆₆(C≡CPh)₄₈Cl₈]^q- and [Au₇₄Ag₆₀(C≡CPh)₄₀Br₁₂]^2-. Both clusters possess a three-concentric-shell Au₁₂@Au₄₂@Ag₆₀ structure. However, the dispositions of the metal atoms, and the ligand coordination modes, of the outermost shells of these clusters are distinctly different. These structural differences reflect the bonding characteristics of the halide ligands. As revealed by density functional theory analysis, these clusters exhibit superatomic electron shell closings at magic numbers of 92 (for q = 4) and 84, respectively, consistent with their spherical shapes. Both clusters exhibit unusual multivalent redox properties.

Progress in controlling the synthesis of atomically precise silver nanoclusters

This short review was designed to summarize the advances in synthesis methods of silver nanoclusters.

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.

Chirality and Surface Bonding Correlation in Atomically Precise Metal Nanoclusters

Chirality is ubiquitous in nature and occurs at all length scales. The development of applications for chiral nanostructures is rising rapidly. With the recent achievements of atomically precise nanochemistry, total structures of ligand-protected Au and other metal nanoclusters (NCs) are successfully obtained, and the origins of chirality are discovered to be associated with different parts of the cluster, including the surface ligands (e.g., swirl patterns), the organic-inorganic interface (e.g., helical stripes), and the kernel. Herein, a unified picture of metal-ligand surface bonding-induced chirality for the nanoclusters is proposed. The different bonding modes of M-X (where M = metal and X = the binding atom of ligand) lead to different surface structures on nanoclusters, which in turn give rise to various characteristic features of chirality. A comparison of Au-thiolate NCs with Au-phosphine ones further reveals the important roles of surface bonding. Compared to the Au-thiolate NCs, the Ag/Cu/Cd-thiolate systems exhibit different coordination modes between the metal and the thiolate. Other than thiolate and phosphine ligands, alkynyls are also briefly discussed. Several methods of obtaining chiroptically active nanoclusters are introduced, such as enantioseparation by high-performance liquid chromatography and enantioselective synthesis. Future perspectives on chiral NCs are also proposed.