Copper uranyl phosphate and arsenate incorporating an organic ligand with a pillared layer structure: [Cu(4,4′-bpy)(UO2)0.5(HPO4)(H2PO4)]·H2O and [Cu(4,4′-bpy)(UO2)0.5(HAsO4)(H2AsO4)]·1.5H2O

Two mixed-metal uranium compounds, [Cu(4,4′-bpy)(UO2)0.5(HPO4)(H2PO4)]·H2O (1) and [Cu(4,4′-bpy)(UO2)0.5(HAsO4)(H2AsO4)]·1.5H2O (2) have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction, fluorescence spectroscopy, and magnetic susceptibility. They are the first examples of mixed-metal uranium phosphate and arsenate incorporating an organic ligand. Their structures contain copper uranyl phosphate/arsenate layers which are covalently linked by 4,4′-bpy pillars to form a 3-D framework structure. The fluorescence spectrum of 1 shows the characteristic vibronic structure of the UO22+ moiety despite the presence of copper(II) ions in its structure. The two compounds are isostructural and crystallize in the monoclinic space group C2/c with a=20.184(4) Å, b=8.921(2) Å, c=19.095(3) Å, β=115.15(1)°, and R1=0.0244 for 1, and a=20.184(1) Å, b=9.0210(5) Å, c=19.714(1) Å, β=114.879(1)°, and R1=0.0399 for 2.