Pillared and open-framework uranyl diphosphonates

The hydrothermal reactions of uranium trioxide, uranyl acetate, or uranyl nitrate with 1,4-benzenebisphosphonic acid in the presence of very small amount of HF at 200 °C results in the formation of three different uranyl diphosphonate compounds, [H3O]2{(UO2)6[C6H4(PO3)(PO2OH)]2[C6H4(PO2OH)2]2[C6H4(PO3)2]}(H2O)2 (Ubbp-1), [H3O]4{(UO2)4[C6H4(PO3)2]2F4}·H2O (Ubbp-2), and {(UO2)[C6H2F2(PO2OH)2(H2O)}2·H2O (Ubbp-3). The crystal structures of these compounds were determined by single crystal X-ray diffraction experiments. Ubbp-1 consists of UO7 pentagonal bipyramids that are bridged by the phosphonate moieties to form a three-dimensional pillared structure. Ubbp-2 is composed of UO5F2 pentagonal bipyramids that are bridged through the phosphonate oxygen atoms into one-dimensional chains that are cross-linked by the phenyl spacers into a pillared structure. The structure of Ubbp-3 is a three-dimensional open-framework with large channels containing water molecules with internal dimensions of approximately 10.9×10.9 Å. Ubbp-1 and Ubbp-2 fluoresce at room temperature.