Supramolecular Confinement of Cyclodextrin-Like Host-Guest Polyoxovanadate in Giant Ag^0/I Nanoclusters

Although polyoxovanadates (POVs) and their silver nanocluster composites have attracted significant research attention owing to their remarkable structural diversity and multifunctional properties, the mechanistic interplay between their dual chemical roles-serving simultaneously as host matrices in supramolecular architectures and as structural templates directing silver nanocluster (Ag NC) assembly-remains insufficiently understood. Herein, we systematically optimized the condensation of {VO_x} (x = 4, 5) tetrahedra or square pyramids around simple anions (S^2- and SO₄ ^2-) to tailor two distinct host-guest cyclodextrin-like POV supermolecules: [S@V₁₆O₄₈]^18- and [SO₄@V₁₄O₄₂]^16-. Remarkably, these two cyclic POVs were generated in situ and have never been observed before, either in vanadate chemistry or in silver nanoclusters, representing a new category of POV condensation species. These two host-guest supramolecular anions function as templates, inducing the formation of the POV-bearing Ag^0/I NCs, dubbed as Ag78 and Ag68. Furthermore, the photothermal conversion efficiency (PCE) of Ag68 and Ag78 is comprehensively discussed and the excellent PCE is attributed to the nonradiation transition process, encompassing the fast deactivation of the excited charge transfer (CT) state and the slow recombination of CT state, as revealed by femtosecond transient absorption spectroscopy. This work not only optimizes the condensation of {VO_x} (x = 4, 5) polyhedral building units to tailor novel host-guest POV supermolecules but also offers a new perspective on supramolecular anion templates in guiding the assembly of silver NCs.