A stable superatomic Cu 6 (SMPP) 6 nanocluster with dual emission.

We have synthesized single crystals of a highly stable Cu 6 nanocluster protected by six ligands of 2-mercapto-5- n -propylpyrimidine (SMPP). This Cu 6 (SMPP) 6 cluster has a quasi-octahedral superatomic Cu 6 core, with the Cu atoms being protected by both -S- and N -bidentate coordination of the SMPP ligands. Interestingly, each Cu atom is linked with an N atom, while the two neighboring Cu atoms on the same triangular facet are linked by the -S- bridge of the ligand. Single-crystal parsing results show that the altered orientation of the SMPP ligands give rise to three packing modes (named as 1, 2, and 3) of the Cu 6 (SMPP) 6 NCs. Apart from the well-organized coordination, this Cu 6 (SMPP) 6 nanocluster exhibits superatomic stability with a metallic core of 4 valence electrons (1S 2 2S 2 ||3S 2 ), enabling to largely balance the interactions between the polynuclear core and delocalized electrons. Interestingly, the Cu 6 (SMPP) 6 NCs display dual emissions in both ultraviolet-visible (UV-Vis) and near-infrared (NIR) regions. First-principles calculations well reproduce the experimental spectrum, shedding light on the nature of excitation states and metal-ligand interactions in the Cu 6 (SMPP) 6 cluster.