Incorporation of Cu2+ Ions into Nanotubular Uranyl Diphosphonates

Three new multidimensional polymetallic uranyl diphosphonates were crystallized under mild hydrothermal conditions: [Cu(H2O)](2){(UO2)(4)F-2[(PO3C6H4)(C6H4PO3H)(3)](2)(bipym)}center dot 6H(2)O (1), [Cu(H2O)](2){(UO2)(4)[(C6H4PO3)(C6H4PO3H)](4)(bipym)} (2), and Cu{(UO2)(C6H4PO3)(2)(bipym)}center dot H2O (3). Compound 1 consists of UO6F pentagonal bipyramids connected by diphosphonate moieties into a tubular channel. The Cu2+ cations are stabilized between the nanotubular subunits by 2,2'-bipyrimidine (bipym). The structure of 2 is similar to 1, except that it consists of relatively rare UO6 tetragonal bipyramids bridged by diphosphonate groups. Compound 3 also contains UO6 tetragonal bipyramids. Unlike compounds 1 and 2, only two of the tetradentate N atoms of the binucleating bipym group are coordinated. All three compounds show luminescent properties under ambient conditions, with evidence of the characteristic vibronically coupled charge-transfer based uranyl cation emissions.