Incorporation of Cu2+ Ions into Nanotubular Uranyl Diphosphonates

Three new multidimensional polymetallic uranyl diphosphonates were crystallized under mild hydrothermal conditions: [Cu­(H2O)]2{(UO2)4F2[(PO3C6H4)­(C6H4PO3H)3]2(bipym)}·6H2O (1), [Cu­(H2O)]2{(UO2)4[(C6H4PO3)­(C6H4PO3H)]4(bipym)} (2), and Cu­{(UO2)­(C6H4PO3)2(bipym)}·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.