Syntheses, structures and luminescent properties of two organic templated uranyl phosphonates

Two organic templated uranyl phosphonates (Hbpi)[(UO2)2(H2O)(PO3C6H5)2(HPO3C6H5)] (1) and (H2dib)0.5[UO2(H2O)(Hhedp)] (2) (bpi = 1-([1,1′-biphenyl]-4-yl)-1H-imidazole, dib = 1,4-di(1H-imidazol-1-yl)butane, H4hedp = 1-hydroxyethylidenediphosphonic acid), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR and photoluminescent spectroscopy. The structures of compounds 1 and 2 have been determined to be layered structures constructed by UO7 pentagonal bipyramids and PO3C tetrahedra of phenylphophonate and hedp groups, respectively. Adjacent layers are packed in AA stacking into the supramolecular structure, in which protonated bpi and dib molecules fill and compensate the negative charge of 1 and 2, respectively. Photoluminescence studies indicate that the two complexes exhibit characteristic green light emission of uranyl cations.