Hybrid Lanthanide–Actinide Peroxide Cage Clusters

A cage cluster consisting of 31 uranyl and 9 Sm³⁺ polyhedra self-assembles in an alkaline aqueous peroxide solution and crystallizes (U₃₁Sm₉). Trimers of Sm³⁺ polyhedra are templated by μ₃-η²:η²:η²-peroxide groups and link to oxo atoms of uranyl ions. Three such trimers link into a ring through uranyl hexagonal bipyramids, and these are attached through six polyhedra to a unit consisting of 21 uranyl hexagonal bipyramids to complete the cage. Luminescence spectra collected with an excitation wavelength of 420 nm reveal fine structure, which is not observed for a cluster containing only uranyl polyhedra