Water-soluble Self-assembled {Pd₈₄ }^Ac Polyoxopalladate Nano-wheel as a Supramolecular Host

Polyoxopalladates (POPs) are a class of self-assembling palladium-oxide clusters that span a variety of sizes, shapes and compositions. The largest of this family, {Pd₈₄ }^Ac , is constructed from 14 building units of {Pd₆ } and lined on the inner and outer torus by 28 acetate ligands. Due to its high water solubility, large hydrophobic cavity and distinct ¹ H NMR fingerprint {Pd₈₄ }^Ac is an ideal molecule for exploring supramolecular behaviour with small organic molecules in aqueous media. Molecular visualisation studies highlighted potential binding sites between {Pd₈₄ }^Ac and these species. Nuclear Magnetic Resonance (NMR) techniques, including ¹ H NMR, ¹ H Diffusion Ordered Spectroscopy (DOSY) and Nuclear Overhauser Spectroscopy (NOESY), were employed to study the supramolecular chemistry of this system. Here, we provide conclusive evidence that {Pd₈₄ }^Ac forms a 1 : 7 host-guest complex with benzyl viologen (BV²⁺ ) in aqueous solution.