Bioinspired phosphate homeostasis for atomically precise regulation of silver nanoclusters

The dynamic dissociation equilibrium of phosphate in living organisms plays a crucial role in maintaining the balance necessary for sustaining life. In the field of metal clusters, [H_{3- x} PO₄] ^{x -} (x = 1-3) anions also serve as effective templates for constructing silver clusters, with their innate structural flexibility bringing tremendous promise for structural regulation. However, current understanding of the effects of phosphate balance on the dynamic assembly of high-nuclearity silver clusters (metal atom number > 100) remains limited. In this study, we first demonstrate that different forms of phosphates (orthophosphate, hydrogen phosphate and dihydrogen phosphate) can controllably provide tetrahedral PO₄ ^3- oxyanions in the basic environment, thereby directing the structural evolution of silver clusters. A multilayered, rosette-shaped 104-nuclei silver nanocluster (Ag104a) is successfully isolated by utilizing Na₃PO₄/Na₂HPO₄ as the PO₄ ^3- source. This unique structure features a silver-containing (PO₄)@Ag₄@(PO₄)₁₂ template layer, enveloped by an outer Ag₁₀₀ shell composed of an Ag₇₂ garland and two Ag₁₄ units. Notably, Ag104a represents the silver alkynyl cluster with the highest number of encapsulated tetrahedral anions to date. In contrast, using NaH₂PO₄ results in the formation of a different co-crystallized silver cluster: Ag104b·Ag108a. Time-dependent ³¹P nuclear magnetic resonance analysis on the reaction solution reflected the different release rates of PO₄ ^3- anions, which can affect the assembly of silver clusters. This work not only makes a significant advancement in the structural regulation of high-nuclearity silver clusters by phosphates, but also offers valuable insights into the intricate interplay between phosphate balance and the dynamic assembly of silver clusters.