Room temperature assembly of a uranyl carboxyphosphonate: Synthesis, characterization and UO22+ hydrolysis

A novel 1-dimensional U(VI) phosphonoacetate, UO2(O3PCH2CO2H)(H2O)·2H2O (1), has been synthesized from the room temperature reaction of uranium nitrate and phosphonoacetic acid (H3PPA) in water. The compound crystallizes in a monoclinic space group (P21, a = 8.3517(5) Å, b = 7.0013(4) Å, c = 8.3728(5) Å, β = 107.310(1)°, Z = 2) and exhibits bonding to the UO22+ through both phosphonate and carboxylate oxygen atoms of the acid unit. The crystal structure, thermal and fluorescent behaviors, and role of UO22+ hydrolysis in the context of ambient versus hydrothermal syntheses are discussed.