An Ultrastable 155-Nuclei Silver Nanocluster Protected by Thiacalix[4]arene and Cyclohexanethiol for Photothermal Conversion.

Thiacalix[4]arenes have emerged as a family of macrocyclic ligands to protect metal nanoparticles, but it remains a great challenge to solve the mystery of their structures at the atomic level, especially for those larger than 2 nm. Here, we report the largest known mixed-valence silver nanocluster [Ag (CyS) (TC4A) Cl ] (Ag155) protected by deprotonated cyclohexanethiol (CySH) and macrocyclic ligand p-tert-butylthiacalix[4]arene (H TC4A). Its single-crystal structure consists of a metallic core of four concentric shells, Ag @Ag @Ag @Ag , lined with a organic skin of 40CyS and 5TC4A and 2Cl . Ag155 manifests an unusual pseudo-5-fold symmetry dictated by the intrinsic metal atom packing and the regioselective distribution of mixed protective ligands. This work not only reveals a macrocyclic ligand effect on the formation of a large silver nanocluster, but also provides a new structural archetype for comprehensively perceiving their interface and metal kernel structures.