Variable control of the electronic states of a silver nanocluster via protonation/deprotonation of polyoxometalate ligands
K. Yonesato, S. Yamazoe, S. Kikkawa, D. Yokogawa, K. Yamaguchi, K. Suzuki
Chem. Sci., Accepted.

The properties of metal nanoclusters depend on both their structures and electronic states. However, in contrast with the significant advances achieved in the synthesis of structurally well-defined metal nanoclusters, the systematic control of their electronic states is still challenging. In particular, the stimuli-responsive and reversible control of the electronic states of metal nanoclusters is attractive from the viewpoint of their practical applications. Recently, we developed a synthesis method for atomically precise Ag nanoclusters using polyoxometalates (POMs) as inorganic ligands. Herein, we exploited the acid/base nature of POMs to reversibly change the electronic state of an atomically precise {Ag27} nanocluster via protonation/deprotonation of the surrounding POM ligands. We succeeded in systematically controlling the electronic states of the {Ag27} nanocluster by adding an acid or a base (0-6 equivalents), which was accompanied by drastic changes in the ultraviolet-visible absorption spectra of the nanocluster solutions. These results demonstrate the great potential of Ag nanoclusters for unprecedented applications in various fields such as sensing, biolabeling, electronics, and catalysis.