Use of Bifunctional Phosphonates for the Preparation of Heterobimetallic 5f−3d Systems

Abstract

The hydrothermal reaction of phosphonoacetic acid (H2PO3CH2C(O)OH, PAA) with UO3 and Cu(C2H3O2)2 .H2O results in the formation of the crystalline heterobimetallic uranium(VI)/copper(II) phosphonates UO2Cu(PO3CH2CO2)(OH)(H2O)2 ( UCuPAA-1), (UO2) 2Cu(PO3CH2CO2)2(H2O)3 (UCuPAA-2), and [H3O][(UO2) 2Cu2(PO3CH2CO2)3(H2O)2 ( UCuPAA-3). The addition of sodium hydroxide to the aforementioned reactions results in the formation of Na[UO2(PO3CH2CO2)].2H2O (NaUPAA-1). These compounds display 1D (UCuPAA-1), 2D (UCuPAA-2, NaUPAA-1), and 3D (UCuPAA-3) architectures wherein the phosphonate portion of the ligand primarily coordinates the uranium(VI) centers; whereas the carboxylate moiety preferentially, but not exclusively, binds to the copper(II) ions. Fluorescence measurements on all four compounds demonstrate that the presence of copper(II) mostly quenches the emission from the uranyl moieties.