Carboxylate engineering for manipulating the optical and assembly properties of copper clusters

Abstract

Surface ligands are critical in the construction and stabilization of atomically precise metal nanoclusters (NCs) with diverse structures, and ligand engineering remains one of the most effective ways to tailor their properties. In this work, we report the synthesis, structure and surface engineering of novel copper nanoclusters co-protected by carboxylic and thioate ligands. The two clusters share the same formula Cu₁₄(RCOO)₆(AdmS)₈ (RCOOH is benzoic acid or 2-[(2,6-dichlorophenyl) amino] benzeneacetic acid, and AdmSH is 1-adamantanethiol) and a similar molecular structure. What is surprising to us, however, is that the optical properties, stability and assembly structures of the two clusters are significantly different, thus strongly indicating the potential of engineering carboxylates for manipulating the physicochemical properties of atomically precise copper NCs. This work not only provides model clusters stabilized by carboxylic ligands for further study of the structure–property relationship, but also outlines the big picture of carboxylic-stabilized metal nanoclusters that will flourish in the near future.