Atomically Precise Metal Nanoclusters: Novel Building Blocks for Hierarchical Structures

Abstract

Atomically precise ligand-protected nanoclusters (NCs) constitutea ni mportant class of compounds that exhibit well-defineds tructures and, when sufficiently small, evident molecular properties. NCs provide versatile building blocks to fabricate hierarchical superstructures. The assembly of NCs indeed offers opportunities to devise new materials with given structures and able to carry out specific functions. In this Concept article, we highlight the possibilities offered by NCs in which the physicochemical properties are controlled by the introductiono ff oreign metal atoms and/or modification of the compositiono f the capping monolayer with functional ligands. Different approaches to assemble NCs into dimers and higher hierarchy structures and the corresponding changes in physicochemical properties are also described.

Electron Transfer in Films of Atomically Precise Gold Nanoclusters

“…Monolayer-protected gold clusters (MPCs) are promising materials in areas such as catalysis, electrocatalysis, sensing, and biomedicine. − Their chemical and physicochemical properties are determined by a subtle combination of structural and electronic factors related to the core and capping ligands. When the intercluster distance is sufficiently small, specific interactions between MPCs may occur and further properties emerge.…”

“…This may happen in the solid state, such as crystals and films, and assemblies. These interactions may affect the magnetic behavior, the optical properties, or the charge state. ,, For example, in single crystals, paramagnetic Au 25 (S- n -butyl) 18 0 forms linear wires in which the odd electrons of individual clusters pair up to generate an antiferromagnetic system, whereas the use of the phenylethanethiolate ligand causes the Au 25 clusters to display ferromagnetism and superparamagnetism depending on the physical state and temperature . For MPCs sufficiently large to display a localized surface plasmon resonance band, the latter can be affected when the intercluster distance is sufficiently small to cause interactions between the conduction electrons of neighboring MPCs. , For smaller, atomically precise clusters, the proximity between cores affects the MPC absorption and emission properties. − Importantly, electronic coupling between the relevant orbitals of clusters and nearby species implies the possibility of observing electron-transfer (ET) reactions.…”

“…These interactions may affect the magnetic behavior, the optical properties, or the charge state. 4,10,11 For example, in single crystals, paramagnetic Au 25 (S-n-butyl) 18 0 forms linear wires in which the odd electrons of individual clusters pair up to generate an antiferromagnetic system, 12 whereas the use of the phenylethanethiolate ligand causes the Au 25 clusters to display ferromagnetism and superparamagnetism depending on the physical state and temperature. 13 For MPCs sufficiently large to display a localized surface plasmon resonance band, the latter can be affected when the intercluster distance is sufficiently small to cause interactions between the conduction electrons of neighboring MPCs.…”

Modulating luminescence and assembled shapes of ultrasmall Au nanoparticles towards hierarchical information encryption

“…It was intriguing to one-pot synthesize the necklace-like AuNAs in a controllable manner, which was largely different from the self-assembly of the pre-prepared NPs strategy. 39,40 The one-pot protocol was simple and convenient, effectively avoiding the aggregate generation during self-assembly of preprepared NPs. Thus, it was interesting to explore the mechanism for one-pot synthesis of the necklace-like AuNAs.…”

Assembling Atomically Precise Noble Metal Nanoclusters Using Supramolecular Interactions

“…Examples include well-defined optical absorption and emission due to quantized energy levels, electrochemical properties, chirality, and chemical reactivity. ,,− Limited investigations have been performed on their collective properties such as magnetism. The presence of various kinds of ligands on the metal core enables the possibility of making specific noncovalent interactions with NMNCs, nanoparticles (NPs), and other molecules. − There are also possibilities of forming inclusion complexes of ligands acting as guests with suitable hosts for the SC of NMNCs. Examples of this branch of NMNCs-assembled materials are beginning to be available.…”