One- and Two-Dimensional Silver and Zinc Uranyl Phosphates Containing Bipyridyl Ligands

The reaction of AgCN with UO2, 4,4'-bipy, and phosphoric acid in water at 160 degrees C under autogeneously generated pressure results in the formation of [Ag(4,4'-bipy)]2[(UO2)2H3(PO4)3] (AgUP-1). Ag(2,2'-bipy)(UO2)2(HPO4)(PO4) (AgUP-2) has been prepared from the hydrothermal reaction (at 180 degrees C) of KAg(CN)2 with UO2(C2H3O2)2.2H2O and 2,2'-bipy. [Zn(2,2'-bipy)]2[UO2(HPO4)3] (ZnUP-1) was isolated from the hydrothermal reaction of UO2, 2,2'-bipyridyl, Zn(CN)2, and H3PO4. Single crystal X-ray diffraction experiments reveal that the structure of AgUP-1 consists of 2infinity[(UO2)2H3(PO4)3]2- expanded autunite-like layers in the [ac] plane, separated by 1infinity[Ag(4,4'-bipy)]+ chains of two-coordinate Ag+ bridged by 4,4'-bipy. The structure of AgUP-2 is composed of chains of edge-sharing UO7 pentagonal bipyramids that are linked by phosphate anions into 2infinity[(UO2)2(HPO4)(PO4)]1- sheets with the beta-uranophane topology that extend in the [ab] plane. Both sides of the sheets are decorated by [Ag(2,2'-bipy)]+ units, where the Ag+ cations are found in distorted trigonal planar environments. The structure of ZnUP-1 is 1D and consists of UO7 pentagonal bipyramids that are connected by phosphate anions that also bind four-coordinate zinc(II) to the periphery of the chains and five-coordinate zinc within the chains. Intense fluorescence from these compounds was observed.