Chiral Superatomic Nanoclusters Ag47 Induced by the Ligation of Amino Acids.

Silver nanoclusters containing Ag0 atoms protected by amino acids were synthesized and characterized. Chiral superatomic silver nanoclusters [Ag47 L12 (C≡Ct Bu)16 ]BF4 (L=l-/d-valine or l-/d-isoleucine) have been prepared by reducing AgC≡Ct Bu and amino acids (AAs) with NaBH4 . Single crystal X-ray diffraction revealed that these clusters have T symmetry, and the Ag47 metal kernel can be viewed as a tetracapped truncated tetrahedron (Ag17 ) surrounded with six W-shaped Ag5 units. The clusters are homochiral as evidenced by CD measurements. As for the strong CD signals, large contributions are found from the occupied Ag s,p states (superatomic D states) near the Fermi level. Electron counting revealed that these clusters are 18-electron systems, suggesting they are superatomic clusters. The superatomic nature with a 1S2 1P6 1D10 configuration was supported by DFT calculations. This work paves the way of taking AAs as facile chiral induction agents for the synthesis of metal nanoclusters.