UO22+-amino hybrid materials: structural variation and photocatalysis properties

Abstract

Four uranyl complexes (UO₂)₂(μ₂-OH)(μ₃-OH)(his)(CH₃CO₂) (his = histidine) (1), [(UO₂)₂(μ₂-OH)(μ₃-OH)₂(gly)]·1.5H₂O (gly = glycine) (2), UO₂(CH₃CO₂)(μ₂-OH)(2,2′-bipy) (3) and UO₂(CH₃CO₂)₂(2,2′-bipy) (4) were synthesized by the reaction of UO₂(CH₃CO₂)₂·2H₂O as the metal source, and histidine, glycine and 2,2′-bipy as the ligand in an aqueous system. They were characterized by elemental analysis, IR, UV-vis, single crystal X-ray diffraction analysis and thermal gravimetric analysis. The structural analysis reveals that complex 1 exhibits a one-dimensional chain structure constructed by the building unit [(UO₂)₄O₁₀(C₆O₂N₃)₂], which further extends the chain into 2D supramolecular architectures by hydrogen bonding interactions. For complex 2, uranyl polyhedrons, through edge-sharing, form a 2D wave-like layer and furthermore connect by hydrogen bonding to form a 3D supramolecular structure. Complex 3 is a discrete UO₂-2,2′-bipy compound UO₂(CH₃CO₂)(OH)(2,2′-bipy). Complex 4 is also a discrete UO₂-acetic-2,2′-bipy compound UO₂(CH₃CO₂)₂(2,2′-bipy) which is similar to complex 3. The adjacent molecules were respectively connected by hydrogen bonding to form a 2D supramolecular network for 3 and a 1D supramolecular chain for 4. In order to determine their functional properties, their photoluminescence was characterized and their photocatalytic properties were also studied firstly.