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-155(CyS)(40)(TC4A)(5)Cl-2] (Ag155) protected by deprotonated cyclohexanethiol (CySH) and macrocyclic ligand p-tert-butylthiacalix[4]arene (H(4)TC4A). Its single-crystal structure consists of a metallic core of four concentric shells, Ag-13@Ag-42@Ag-30@Ag-70, lined with a organic skin of 40CyS(-) and 5TC4A(4-) 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.

Automated summary

This study reports the single-crystal structure of the largest known mixed-valence silver nanoclusters protected by thiacalix[4]arenes and cyclohexanethiol. The structure consists of a metallic core with four concentric shells, surrounded by an organic skin. This work not only reveals the influence of macrocyclic ligands on the formation of large silver nanoclusters, but also provides a new structural archetype.