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Understanding the fluorescence resonance energy transfer (FRET) of metal nanoparticles at the atomic level has long been a challenge due to the lack of accurate systems with definite distance and orientation of molecules. Here we present the realization of achieving FRET between two atomically precise copper nanoclusters through cocrystallization-induced spatial confinement. In this study, we demonstrate the establishment of FRET in a cocrystallized Cu 8 ( p -MBT) 8 (PPh 3 ) 4 @Cu 10 ( p -MBT) 10 (PPh 3 ) 4 system by exploiting the overlapping spectra between the excitation of the Cu 10 ( p -MBT) 10 (PPh 3 ) 4 cluster and the emission of the Cu 8 ( p -MBT) 8 (PPh 3 ) 4 cluster, combined with accurate control over the confined space between the two nanoclusters. Density functional theory is employed to provide deeper insights into the role of the distance and dipole orientations of molecules to illustrate the FRET procedure between two cluster molecules at the electronic structure level. Understanding FRET of metal nanoparticles at the atomic level has long been a challenge. Here, the authors have achieved FRET activity with atomically precise Cu clusters by using a cocrystallisation-induced spatial confinement strategy.

The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1–3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au 25 , Au 38 , Au 144 , Au 333 , Au ∼520 and Au ∼940 nanoparticles. Our results clearly map out three distinct states: metallic (size larger than Au 333 , that is, larger than 2.3 nm), transition regime (between Au 333 and Au 144 , that is, 2.3–1.7 nm) and non-metallic or excitonic state (smaller than Au 144 , that is, smaller than 1.7 nm). The transition also impacts the catalytic properties as demonstrated in both carbon monoxide oxidation and electrocatalytic oxidation of alcohol. Little is known about the transition of a metal nanoparticle from the plasmonic to excitonic state. Here, the authors map this evolution in atomically precise gold nanoparticles, a critical step for understanding the origins of surface plasmon resonance, metallic bonding, and catalytic behaviour.

Gold-copper alloys have rich forms. Here we report an atomically resolved [Au 52 Cu 72 ( p -MBT) 55 ] + Cl − nanoalloy ( p -MBT = SPh- p -CH 3 ). This nanoalloy exhibits unusual structural patterns. First, two Cu atoms are located in the inner 7-atom decahedral kernel (M 7 , M = Au/Cu). The M 7 kernel is then enclosed by a second shell of homogold (Au 47 ), giving rise to a two-shelled M 54 (i.e. Au 52 Cu 2 ) full decahedron. A comparison of the non-truncated M 54 decahedron with the truncated homogold Au 49 kernel in similar-sized gold nanoparticles provides for the first time an explanation for Marks decahedron truncation. Second, a Cu 70 (SR) 55 exterior cage resembling a 3D Penrose tiling protects the M 54 decahedral kernel. Compared to the discrete staple motifs in gold:thiolate nanoparticles, the Cu-thiolate surface of Au 52 Cu 72 forms an extended cage. The Cu-SR Penrose tiling retains the M 54 kernel’s high symmetry ( D 5h ). Third, interparticle interactions in the assembly are closely related to the symmetry of the particle, and a “quadruple-gear-like” interlocking pattern is observed. The formation of Marks truncated decahedra in nanoparticles is ubiquitous but the mechanism has not been fully understood. Here, the authors provide atomic-level insights by creating a non-truncated Au 52 Cu 72 (SR) 55 decahedral nanocluster and comparing it with the truncated homogold decahedra.

The preparation of 2-Oxazolidinones using CO 2 offers opportunities for green chemistry, but multi-site activation is difficult for most catalysts. Here, A low-nuclear Ag 4 catalytic system is successfully customized, which solves the simultaneous activation of acetylene (-C≡C) and amino (-NH-) and realizes the cyclization of propargylamine with CO 2 under mild conditions. As expected, the Turnover Number (TON) and Turnover Frequency (TOF) values of the Ag 4 nanocluster (NC) are higher than most of reported catalysts. The Ag 4 * NC intermediates are isolated and confirmed their structures by Electrospray ionization (ESI) and 1 H Nuclear Magnetic Resonance ( 1 H NMR). Additionally, the key role of multiple Ag atoms revealed the feasibility and importance of low-nuclear catalysts at the atomic level, confirming the reaction pathways that are inaccessible to the Ag single-atom catalyst and Ag 2 NC. Importantly, the nanocomposite achieves multiple recoveries and gram scale product acquisition. These results provide guidance for the design of more efficient and targeted catalytic materials. The preparation of 2-Oxazolidinones using carbon dioxide offers a productive yet clean synthesis route. Here, a low-nuclear Ag 4 nanocluster catalytic system helps the simultaneous activation and the cyclization of propargylamine with CO 2 .

Colorful circularly polarized luminescence materials are desired for 3D displays, information security and asymmetric synthesis, in which single-emitted materials are ideal owing to self-absorption avoidance, evenly entire-visible-spectrum-covered photon emission and facile device fabrication. However, restricted by the synthesis of chiral broad-luminescent emitters, the realization and application of high-performing single-emitted full-color circularly polarized luminescence is in its infancy. Here, we disclose a single-emitted full-color circularly polarized luminescence system (spiral full-color emission generator), composed of whole-vis-spectrum emissive quantum dots and chiral liquid crystals. The system achieves a maximum luminescence dissymmetry factor of 0.8 and remains an order of 10 −1 in visible region by tuning its photonic bandgap. We then expand it to a series of desired customized-color circularly polarized luminescence, build chiral devices and further demonstrate the working scenario in the photoinduced enantioselective polymerization. This work contributes to the design and synthesis of efficient chiroptical materials, device fabrication and photoinduced asymmetric synthesis. Circularly polarised luminescence (CPL) is essential for asymmetric synthetic photochemistry. Here, the authors integrate white quantum dots with chiral nematic liquid crystal or liquid crystal polymer to achieve single-emitted tuneable full-colour or white CPL for enantioselective polymerization.

Although the hollow icosahedral M 12 kernel has been extensively observed in metal nanoclusters, its origin remains a mystery. Here we report a reasonable avenue for the generation of the hollow icosahedron: the kernel collapse from several small nano-building blocks to an integrated hollow icosahedron. On the basis of the Au alloying processes from Ag 28 Cu 12 (SR) 24 to the template-maintained Au x Ag 28-x Cu 12 (SR) 24 and then to the template-transformed Au 12 Cu y Ag 32-y (SR) 30 , the kernel evolution/collapse from “tetrahedral Ag 4  + 4 ∗ Ag 3 ” to “tetrahedral Au 4  + 4 ∗ M 3 (M = Au/Ag)” and then to “hollow icosahedral Au 12 ” is mapped out. Significantly, the “kernel collapse” from small-sized nano-building blocks to large-sized nanostructures not only unveils the formation of hollow icosahedral M 12 in this work, but also might be a very common approach in constructing metallic kernels of nanoclusters and nanoparticles (not limited to the M 12 structure). The origin of the hollow icosahedral M 12 kernel in metal nanoclusters is under debate. Here the authors demonstrate the Au alloying-induced kernel collapse from small-sized nano-building blocks as a viable approach for the generation of hollow icosahedral M 12 kernel in metal nanoclusters.

Dual emission (DE) in nanoclusters (NCs) is considerably significant in the research and application of ratiometric sensing, bioimaging, and novel optoelectronic devices. Exploring the DE mechanism in open-shell NCs with doublet or quartet emissions remains challenging because synthesizing open-shell NCs is difficult due to their inherent instability. Here, we synthesize two dual-emissive M 1 Ag 13 (PFBT) 6 (TPP) 7 (M = Pt, Pd; PFBT = pentafluorobenzenethiol; TPP = triphenylphosphine) NCs with a 7-electron open-shell configuration to reveal the DE mechanism. Both NCs comprise a crown-like M 1 Ag 11 kernel with Pt or Pd in the center surrounded by five PPh 3 ligands and two Ag(SR) 3 (PPh 3 ) motifs. The combined experimental and theoretical studies revealed the origin of DE in Pt 1 Ag 13 and Pd 1 Ag 13 . Specifically, the high-energy visible emission and the low-energy near-infrared emission arise from two distinct quartet excited states: the core-shell charge transfer and core-based states, respectively. Moreover, PFBT ligands are found to play an important role in the existence of DE, as its low-lying π * levels result in energetically accessible core-shell transitions. This novel report on the dual-quartet phosphorescent emission in NCs with an open-shell electronic configuration advances insights into the origin of dual-emissive NCs and promotes their potential application in magnetoluminescence and novel optoelectronic devices. Exploring the dual-emission mechanism in open-shell nanoclusters with doublet or quartet emissions remains challenging. Here, the authors reveal the origin of dual-quartet phosphorescent emission in the open-shell M1Ag13 (M = Pt, Pd) nanoclusters.

Metal nanoclusters have served as an emerging class of programmable nanomaterials with customized structures. However, it remains highly challenging to achieve the single-atom regulation of metal nanoclusters without altering their structural frameworks. Here, we achieve the single-point defects manipulation based upon a cluster pair of Au 21 and Au 22 by meticulously complementing the surface defects of the former nanocluster with an additional single-Au complex. The two nanoclusters exhibited identical geometric structures, but their pronounced quantum-confinement effects resulted in different electronic properties, evident in their distinct optical absorption and emission characteristics. Temperature-dependent steady-state photoluminescence spectra and femtosecond transient absorption spectra showed that the manipulation of a single-point defect in Au 22 inhibited non-radiative decay pathways, reduced electron loss at higher energy levels, and accelerated intersystem crossing, which ultimately enhanced its emission intensity. Overall, the Au 21 and Au 22 cluster system in this study provides a cluster platform with controllable surface single-point defects, enabling the regulation of the photophysical dynamics at the atomic level. The properties of atomically precise nanoclusters depend on their structural composition, but controlling them is challenging. Here, the authors demonstrate the manipulation of single-point defects, converting Au 21 into Au 22 and thereby regulating the photophysical dynamics.

Whole series of nanoparticles have now been reported, but probing the competing or coexisting effects in their synthesis and growth remains challenging. Here, we report a bi-nanocluster system comprising two ultra-small, atomically precise nanoclusters, AuAg 24 (SR) 18 − and Au 2 Ag 41 (SR) 26 (Dppm) 2 + (SR = cyclohexyl mercaptan, Dppm = bis(diphenylphosphino)-methane). The mechanism by which these two nanoclusters coexist is elucidated, and found to entail formation of the unstable AuAg 24 (SR) 18 − , followed by its partial conversion to Au 2 Ag 41 (SR) 26 (Dppm) 2 + in the presence of di-phosphorus ligands, and an interdependent bi-nanocluster system is established, wherein the two oppositely charged nanoclusters protect each other from decomposition. AuAg 24 (SR) 18 and Au 2 Ag 41 (SR) 26 (Dppm) 2 are fully characterized by single crystal X-ray diffraction (SC-XRD) analysis – it is found that their co-crystallization results in single crystals comprising equimolar amounts of each. The findings highlight the interdependent relationship between two individual nanoclusters, which paves the way for new perspectives on nanocluster formation and stability. Despite recent progress in individual nanocluster synthesis, understanding the competing or coexisting effects between particles in solution remains challenging. Here, the authors present the synthesis of a bi-nanocluster system comprising two atomically precise nanoclusters, and map out the interdependent relationship between them.

The growth of nanoparticles along one or two directions leads to anisotropic nanoparticles, but the nucleation (i.e., the formation of small seeds of specific shape) has long been elusive. Here, we show the total structure of a seed-sized Au 56 nanoprism, in which the side Au{100} facets are surrounded by bridging thiolates, whereas the top/bottom {111} facets are capped by phosphine ligands at the corners and Br − at the center. The bromide has been proved to be the key to effectively stabilize the Au{111} to fulfill a complete face-centered-cubic core. In femtosecond electron dynamics analysis, the non-evolution of transient absorption spectra of Au 56 is similar to that of larger-sized gold nanoclusters ( n  > 100), which is ascribed to the completeness of the prismatic Au 56 core and an effective electron relaxation pathway created by the stronger Au-Au bonds inside. This work provides some insights for the understanding of plasmonic nanoprism formation. The formation pathway of shape-anisotropic nanoparticles is difficult to characterize and not well understood. The authors synthesize a prismatic-shaped Au 56 nanocluster as possible seed of a prismatic nanoparticle and characterize the structure and ligand bonding motifs, providing insight into the formation and surface protection mechanisms.