Fig. 1. (a) Cartoon illustrating the cubic host cage [M₈L₁₂]¹⁶⁺, abbreviated as H (R = H), emphasising the cubic array of Co(ii) ions and the disposition of one bridging ligand; and its derivatives bearing substituents at the twenty-four externally-directed pyridyl C⁴ positions H^W (R = CH₂OH), and H^PEG [R = –(CH₂OCH₂)₃CH₂OMe]. (b) A view of the complete cage structure, highlighting the guest binding cavity space (V = 409 ų).