Intra-cluster growth meets inter-cluster assembly: The molecular and supramolecular chemistry of atomically precise nanoclusters

The molecular and supramolecular chemistry of atomically precise nanoclusters encompasses intra-cluster growth, inter-cluster assembly, and cluster-based host-guest nanosystems, and is a flourishing area of nano-research. This review presents recent advances in the molecular and the supramolecular chemistry of nanoclusters in atomic precision. We first present the intra-cluster growth modes of nanoclusters, including kernel fusion, interpenetration, cluster of clusters, Au-4 tetrahedra as building blocks, shell by shell, and layer by layer. These intra-cluster growth modes reflect the molecular chemistry of nanoclusters. We further discuss the inter-cluster assembly of nanoclusters, which belongs to the realm of supramolecular chemistry - cluster-based crystal lattices, metal-organic frameworks, and aggregation-induced emission materials are included. Then, the cluster-based host-guest nanosystems are reviewed. Nanoclusters can serve as both hosts, to absorb functional molecular guests; and also act as guests, anchored onto/into 1D nanowires, 2D nanosheets, and 3D nanostructures. The techniques of molecular/-supramolecular chemistry are able to tune the chemical and physical properties of nanoclusters, which are introduced in these sections. Finally, scope for improvements and future perspectives on this research field are highlighted as well. This review will be useful to researchers attempting to understand and/or design new nanoclusters or cluster-based hybrid nanomaterials with desired functionalities. (C) 2019 Published by Elsevier B.V.