N-heterocyclic carbene coordinated metal nanoparticles and nanoclusters

N-heterocyclic carbenes (NHCs) represent one of the most important organic ligands in coordination chemistry, and have been recently attracting increasing attention in nanoscience. This review aims to provide an overview on recent research advances on the use of NHCs as stabilizing agents and functionality modifiers for metal nanoparticles (NPs) and nanoclusters (NCs). The review begins with the general introduction of NHCs and the initial discovery of NHC ligation on metal NPs. With the development of several effective strategies to decorate metal NPs with NHCs, the research enthusiasm for NHC-stabilized metal NPs has been expanded. NHCs on heterogeneous metal nanocatalysts help to modify the electronic and steric properties of the catalysts and thus improve their catalytic performances including reactivity, selectivity, stability and recyclability. For example, NHC-ligated gold NPs has been demonstrated to possess remarkably enhanced stability that cannot be achieved by other ligand systems. Moreover, significant progress has been made in the synthesis of atomically precise NHC-stabilized metal NCs and their crystallographic structure analysis, providing the unprecedented opportunity in understanding the carbene-metal interface at the atomic level. At the end of the review, personal perspectives on the further development of this embryonic while promising field is discussed.