ABSTRACT
Thiacalix[4]arenes as a family of promising ligands have been widely used to construct polynuclear metal clusters, but scarcely employed in silver nanoclusters. Herein, an anion-templated Ag88 nanocluster (SD/Ag88a) built from p-tert-butylthiacalix[4]arene (H4TC4A) is reported. Single-crystal X-ray diffraction reveals that C4-symmetric SD/Ag88a resembles a metal-organic super calix comprised of eight TC4A4- as walls and 88 silver atoms as base, which can be deconstructed to eight [CrO4@Ag11(TC4A)(EtS)4(OAc)] secondary building units arranged in an annulus encircling a CrO42- in the center. Local and global anion template effects from chromates are individually manifested in SD/Ag88a. The solution stability and hierarchical assembly mechanism of SD/Ag88a are studied by using electrospray mass spectrometry. The Ag88 nanocluster represents the highest nuclearity metal cluster capped by TC4A4-. This work not only exemplify the specific macrocyclic effects of TC4A4- in the construction of silver nanocluster but also realize the shape heredity of TC4A4- to overall silver super calix.
ABSTRACT
Due to the elusive nature of polyoxometallates (POMs) in the assembly of silver clusters, POMs trapped by silver clusters are usually different from the pristine form, which surely increases the novelty of the assembly results but makes the final structure predictability challenging. Herein, three novel high-nuclearity silver-thiolate clusters trapping two kinds of classical POMs, Lindqvist-Mo6O192- and V10O286-, are reported. They are identified to be [(V10O28)@Ag44] (SD/Ag44a), [(V10O28)@Ag46] (SD/Ag46), and [(Mo6O19)@Ag44] (SD/Ag44b) clusters, which are further extended to 1D chain, 2D sql layer, and 3D pcu framework, respectively. Of note, SD/Ag44b contains a regular cubic Mo6O19 core sealed by an Ag44(EtS)24 shell in a pseudo-sodalite unit and six SCl4 planar squares connecting the respective adjacent silver tetragonal faces. This structure is a novel zeolite closely related to the natural alumino-silicate 'sodalite' but exceptionally made of core-shell silver clusters. Moreover, the Oh symmetric Mo6O192- templates an Oh symmetric Ag44 cluster in SD/Ag44b, realizing authentic symmetry delivery from guest to host in this system. This is a rare silver cluster family with classical POMs encapsulated.
