Atomically Tailored Gold Nanoclusters for Catalytic Application.

Recent advances in the synthetic chemistry of atomically precise metal nanoclusters (NCs) have significantly broadened the accessible sizes and structures. Such particles are well defined and have intriguing properties, thus, they are attractive for catalysis. Especially, those NCs with identical size but different core (or surface) structure provide unique opportunities that allow the specific role of the core and the surface to be mapped out without complication by the size effect. Herein, we summarize recent work with isomeric Aun NCs protected by ligands and isostructural NCs but with different surface ligands. The highlighted work includes catalysis by spherical and rod-shaped Au25 (with different ligands), quasi-isomeric Au28 (SR)20 with different R groups, structural isomers of Au38 (SR)24 (with identical R) and Au38 S2 (SR)20 with body-centred cubic (bcc) structure, and isostructural [Au38 L20 (PPh3 )4 ]2+ (different L). These isomeric and/or isostructural NCs have provided valuable insights into the respective roles of the kernel, surface staples, and the type of ligands on catalysis. Future studies will lead to fundamental advances and development of tailor-made catalysts.

Atom-Precise Modification of Silver(I) Thiolate Cluster by Shell Ligand Substitution: A New Approach to Generation of Cluster Functionality and Chirality.

To realize the molecular design of new functional silver(I) clusters, a new synthetic approach has been proposed, by which the weakly coordinating ligands NO3- in a Ag20 thiolate cluster precursor can be substituted by carboxylic ligands while keeping its inner core intact. By rational design, novel atom-precise carboxylic or amino acid protected 20-core Ag(I)-thiolate clusters have been demonstrated for the first time. The fluorescence and electrochemical activity of the postmodified Ag20 clusters can be modulated by alrestatin or ferrocenecarboxylic acid substitution. More strikingly, when chiral amino acids were used as postmodified ligands, CD-activity was observed for the Ag20 clusters, unveiling an efficient way to obtain atom-precise chiral silver(I) clusters.

Self-Assembly of a Stable Silver Thiolate Nanocluster Encapsulating a Lacunary Keggin Phosphotungstate Anion.

A polyoxometalate-templated silver(I) thiolate nanocluster has been synthesized by a one-pot reaction in high yield. This novel and stable nanocluster exhibits a core-shell structure with a Ag67S36 shell and two lacunary Keggin [PW9O34]9- cores, which is fully characterized by X-ray crystallography, X-ray photoelectron spectroscopy, UV-vis, powder X-ray diffraction, and cyclic voltammetry.

Tandem Silver Cluster Isomerism and Mixed Linkers to Modulate the Photoluminescence of Cluster-Assembled Materials.

Silver chalcogenolate cluster assembled materials (SCAMs) are a category of promising light-emitting materials the luminescence of which can be modulated by variation of their building blocks (cluster nodes and organic linkers). The transformation of a singly emissive [Ag12 (SBut )8 (CF3 COO)4 (bpy)4 ]n (Ag12 bpy, bpy=4,4'-bipyridine) into a dual-emissive [(Ag12 (SBut )6 (CF3 COO)6 (bpy)3 )]n (Ag12 bpy-2) via cluster-node isomerization, the critical importance of which was highlighted in dictating the photoluminescence properties of SCAMs. Moreover, the newly obtained Ag12 bpy-2 served to construct visual thermochromic Ag12 bpy-2/NH2 by a mixed-linker synthesis, together with dichromatic core-shell Ag12 bpy-2@Ag12 bpy-NH2 -2 via solvent-assisted linker exchange. This work provides insight into the significance of metal arrangement on physical properties of nanoclusters.

Layer-sliding-driven crystal size and photoluminescence change in a novel SCC-MOF.

A novel silver-chalcogenolate cluster-based framework Ag12TPPA·AA with long-lived afterglow was successfully synthesized. It transformed into more densely packed Ag12TPPA·AB and Ag12TPPA·ABC by layer sliding accompanied by macroscopic crystal contraction and changing luminescence.