Single-atom "surgery" on chiral all-dialkynyl-protected superatomic silver nanoclusters

The manipulation of single atom within the metallic kernel of nanoclusters has attracted considerable attention due to its potentials to elucidate kernel-based structure-property relationships at the single-atom level. Herein, new-designed chiral bialkynyl ligands, have been chosen as protective agents to isolate two pairs of 8-electron superatomic silver nanoclusters, R/S-Ag39 and R/S-Ag40. X-ray diffraction analysis reveals that Ag39 and Ag40 with the same number of chiral ligands, possess a closely analogous silver skeleton but a single-atomic difference. The incorporation of an extra Ag^40th atom into Ag40 evokes two significant changes of structure and property compared to Ag39: (i) a reduction in the symmetry of the entire nanocluster, resulting in an enhancement of kernel-related asymmetry g-factor; (ii) a regulation of the transitions (1P → 1D and Ligand_(π) → 1D) of excited state, leading to a second near-infrared (NIR-II, 1000-1700 nm) phosphorescent emission red-shift from 1088 to 1150 nm. This work not only provides vital insights into the relationship between structures and ground/excited states chiroptical activities at the single-atom level, but also presents bialkynyl as a promising stabilizing agent for building superatomic metal nanoclusters.