Hybrid Rare-Earth(III)/Bismuth(III) Clusters Assembled with Phosphonates

tert-Butylphosphonic acid and rare-earth precursors are employed to construct four trinuclear rare-earth phosphonate clusters, RE₃(^tBuPO₃)₂(hfac)₅(CH₃OH)₈]·2CH₃OH (RE = Eu, Y, Pr, and Sm; hfac = hexafluoroacetylacetonate), which are composed of three RE³⁺ ions alternately bridged by two phosphonates. With the introduction of bismuth oxido diketonate, [Bi₉O₇(hfac)₁₃], three different types of rare-earth/bismuth phosphonate clusters, Bi₁₂RE₂ (RE = Pr and Sm), Bi₆Eu₇, and Bi₆Y₉, are successfully obtained via variation of the reaction conditions, and they are the first reported examples of bismuth–oxo clusters encapsulated by cyclic rare-earth–oxo or rare-earth/bismuth–oxo phosphonate clusters, respectively. These clusters show obvious absorption in the UV region, and the Eu-containing clusters exhibit bright-red fluorescence.