From aqueous speciation to supramolecular assembly in alkaline earth-uranyl polyoxometalatesElectronic supplementary information (ESI) available: Experimental details, characterization data (PXRD, EDX, Raman, SAXS, microscopy), crystallographic data (CIF). CCDC 1565926 for Sr@U24 and 1565927 for Ca@U24. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7cc05357f

The interplay between aqueous alkaline earth (Ca, Sr, Ba) polycationic speciation and uranyl-peroxide polyoxometalate self-assembly and evolution is described here using solution (Raman and X-ray scattering) and solid-state (microscopy, X-ray diffraction) characterization. Supramolecular assembly of Sr-encapsulated and decorated polyanions and polycations yields the fourth largest inorganic unit cell reported from single-crystal X-ray diffraction. Macrocation and macroanion Sr-uranyl hybrid capsules self-assemble into an ionic lattice, presenting the fourth largest inorganic unit cell reported.