Assembly of the Thiolated [Au 1 Ag 22 (S‐Adm) 12 ] 3+ Superatom Complex into a Framework Material through Direct Linkage by SbF 6 − Anions

Site-specific substitution in atomically precise carboranethiol-protected nanoclusters and concomitant changes in electronic properties

We report the synthesis of [Ag17(o1-CBT)12]3- abbreviated as Ag17, a stable 8e⁻ anionic cluster with a unique Ag@Ag12@Ag4 core-shell structure, where o1-CBT is ortho-carborane-1-thiol. By substituting Ag atoms with Au and/or Cu at specific sites we created isostructural clusters [AuAg16(o1-CBT)12]3- (AuAg16), [Ag13Cu4(o1-CBT)12]3- (Ag13Cu4) and [AuAg12Cu4(o1-CBT)12]3- (AuAg12Cu4). These substitutions make systematic modulation of their structural and electronic properties. We show that Au preferentially occupies the core, while Cu localizes in the tetrahedral shell, influencing stability and structural diversity of the clusters. The band gap expands systematically (2.09 eV for Ag17 to 2.28 eV for AuAg12Cu4), altering optical absorption and emission. Ultrafast optical measurements reveal longer excited-state lifetimes for Cu-containing clusters, highlighting the effect of heteroatom incorporation. These results demonstrate a tunable platform for designing nanoclusters with tailored electronic properties, with implications for optoelectronics and catalysis.

Inflection of Resistive Switching Behavior in Atomically Precise Silver Cluster-Assembled Materials

Bottom-up design of electronic materials based on nanometer-sized building blocks requires precise control over their self-assembly process. Atomically precise metal nanoclusters (NCs) are the well-characterized building blocks for crafting tunable nanomaterials. Here, a solution-processed assembly of a newly synthesized molecular silver nanocluster (0 D Ag12-NC) into a 1D nanocluster chain (1 D Ag12-CAM) is mediated by 4,4'-bipyridine linker Both 0 D Ag12-NC and 1 D Ag12-CAM consist of Ag12 core that adopts the cuboctahedron geometry protected by organic ligands. The resistive switching devices are fabricated in a sandwich-like structure of ITO (Indium tin oxide)/X/Ag (where X is either 0 D Ag12-NC or 1 D Ag12-CAM). The device based on 1 D Ag12-CAM exhibited excellent resistive switching behaviour, enduring up to 1000 cycles and boasting a fivefold higher Ion/Ioff ratio compared to the device based on the molecular 0 D Ag12-NC nanocluster. Furthermore, the device based on 1 D Ag12-CAM demonstrated negative differential resistance (NDR) phenomena, achieving a peak-to-valley ratio of 2.34 with a switching efficiency of 23 Ns. This work highlights the importance of interconnecting molecular nanoclusters into 1D nanocluster chains for fine-tuning resistive memory properties in futuristic electronic appliances.

Observing atomically precise nanocluster aggregates in solution by mass photometry

We report the first mass photometric characterization of nanoaggregates of atomically precise nanoclusters (NCs) in solution. The differently-sized nanoaggregates of silver-gold alloy NCs, [Ag11-xAux(DPPB)5Cl5O2]2+ [x = 1-5 and DPPB = 1,4-bis(diphenylphosphino)butane], formed in solution, were examined by mass photometry (MP) with a protein calibration. In addition, we conducted MP studies of varying solvent composition to understand the structural evolution of nanoaggregates. The masses of nanoaggregates were correlated to structures of 15 to 50 nm diameter observed in cryo-electron microscopy.

Synthesis and luminescence properties of two silver cluster-assembled materials for selective Fe3+ sensing

Silver cluster-assembled materials (SCAMs) are emerging light-emitting materials with molecular-level structural designability and unique photophysical properties. Nevertheless, the widespread application scope of these materials is severely curtailed by their dissimilar structural architecture upon immersing in different solvent media. In this work, we report the designed synthesis of two unprecedented (4.6)-connected three-dimensional (3D) luminescent SCAMs, [Ag₁₂(S^tBu)₆(CF₃COO)₆(TPEPE)₆]_n (denoted as TUS 1), TPEPE = 1,1,2,2-tetrakis(4-(pyridin-4-ylethynyl)phenyl)ethene and [Ag₁₂(S^tBu)₆(CF₃COO)₆(TPVPE)₆]_n (denoted as TUS 2), TPVPE = 1,1,2,2-tetrakis(4-((E)-2-(pyridin-4-yl)vinyl)phenyl)ethene, composed of an Ag₁₂ cluster core connected by quadridentate pyridine linkers. Attributed to their exceptional fluorescence properties with absolute quantum yield (QY) up to 9.7% and excellent chemical stability in a wide range of solvent polarity, a highly sensitive assay for detecting Fe³⁺ in aqueous medium is developed with promising detection limits of 0.05 and 0.86 nM L^-1 for TUS 1 and TUS 2 respectively, comparable to the standard. Furthermore, the competency of these materials to detect Fe³⁺ in real water samples reveals their potential application in environmental monitoring and assessment.

Tertiary Chiral Nanostructures from C-H⋅⋅⋅F Directed Assembly of Chiroptical Superatoms

We report the synthesis and structure of tertiary chiral nanostructures with 100 % optical purity. A novel synthetic strategy, using chiral reducing agent, R and S-BINAPCuBH₄ (BINAP is 2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl), is developed to access to atomically precise, intrinsically chiral [Au₇ Ag₆ Cu₂ (R- or S-BINAP)₃ (SCH₂ Ph)₆ ]SbF₆ nanoclusters in one-pot synthesis. The clusters represent the first tri-metallic superatoms with inherent chirality and fair stability. Both metal distribution (primary) and ligand arrangement (secondary) of the enantiomers exhibited perfect mirror images, and unprecedentedly, the self-assembly driven by the C-H⋅⋅⋅F interaction between the phenyl groups of the superatom moieties and SbF₆ ^- anions induced the formation of bio-mimic left- and right-handed helices, achieving the tertiary chiral nanostructures. DFT calculations revealed the connections between the molecular details and chiral optical activity.

Assembly-Induced Strong Circularly Polarized Luminescence of Spirocyclic Chiral Silver(I) Clusters

Spirocyclic Ag₉ clusters, as a new form of intrinsically chiral metal clusters, were constructed through vertex-sharing of two in-situ-generated heteroaryl diide-centered metal rings. Such core-peripheral type clusters exhibit versatile photoluminescent and chiroptical behavior under different aggregation conditions. In contrast to a ligand-based fluorescence emission in a diluted solution of the clusters, a solvent polarity-caused assembly gives rise to new cluster-based phosphorous luminescence owing to radiative mode switching and aggregation-induced emission. Assembly of cluster enantiomers leads to micrometer-long helical nanofibers, whose handedness is determined by absolute configuration of individual spirocyclic clusters. Benefiting from exciton couplings of helical arrangements of chelating ligands at molecular and microscopic levels, the assembled film of cluster enantiomers exhibits circularly polarized luminescence with a high anisotropy factor (0.16).