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

Abstract

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 [Ag₁₅₅ (CyS)₄₀ (TC4A)₅ Cl₂ ] (Ag155) protected by deprotonated cyclohexanethiol (CySH) and macrocyclic ligand p-tert-butylthiacalix[4]arene (H₄ TC4A). Its single-crystal structure consists of a metallic core of four concentric shells, Ag₁₃ @Ag₄₂ @Ag₃₀ @Ag₇₀ , 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.

Keywords: C5h Symmetry; ESI-MS; Photothermal Conversion; Silver Nanocluster; Thiacalix[4]arenes.