Symmetry Breaking of Atomically Precise Fullerene-like Metal Nanoclusters

Here we report a neutral fullerene-like core–shell homosilver Ag 13 @Ag 20 nanocluster that is fully protected by an achiral bidentate thiolate ligand (9,12-dimercapto-1,2- closo -carborane, C 2 B 10 H 10 S 2 H 2 ), which crystallizes in centrosymmetric space group R 3̅. Continuous Cu doping in the dodecahedral shell first induced symmetry breaking to generate chiral Ag 13 @Ag 20- n Cu n (6 ≥ n ≥ 2) containing two acetonitrile ligands in space group P 2 1 2 1 2 1, and then produced symmetric all-thiolated Ag 13 @Ag 20- n Cu n (20 ≥ n ≥ 13) in the higher space group Im 3̅. The selectively copper-doped Ag 13 @Ag 20- n Cu n (6 ≥ n ≥ 2) cluster has its structure reorganized to a lower symmetry that shows chiroptical activity. Moreover, structural distortion of Ag 13 @Ag 20- n Cu n (6 ≥ n ≥ 2) further expanded in chiral R -/ S -propylene oxide, which induced a more prominent core-based CD response. This work revealed a novel mechanism of chirality generation at the atomic level through asymmetric shell-doping of metal nanoclusters, which provides new insight into the origin of chirality in inorganic nanostructures.