Uranium(VI) Complexes with a Calix[4]arene-Based 8-Hydroxyquinoline Ligand: Thermodynamic and Structural Characterization Based on Calorimetry, Spectroscopy, and Liquid-Liquid Extraction.

ABSTRACT: The environmental aspects of ore processing and waste treatment call for an optimization of applied technologies. There, understanding of the structure and complexation mechanism on a molecular scale is indispensable. Here, the complexation of UVI with a calix[4]arene-based 8-hydroxyquinoline ligand was investigated by applying a wide range of complementary methods. In solution, the formation of two complex species was proven with stability constants of log?ß1:1=5.94±0.02 and log?ß2:1=6.33±0.01, respectively. The formation of the 1:1 complex was found to be enthalpy driven [?H1:1=(-71.5±10.0)?kJ?mol-1; T?S1:1=(-37.57±10.0)?kJ?mol-1], whereas the second complexation step was found to be endothermic and entropy driven [?H2:1=(32.8±4.0)?kJ?mol-1; T?S2:1=(68.97±4.0)?kJ?mol-1]. Moreover, the molecular structure of [UO2(H6L)(NO3)](NO3) (1) was determined by single-crystal X-ray diffraction. Concluding, radiotoxic UVI was separated from a EuIII-containing solution by the calix[4]arene-based ligand in solvent extractions.

SUBMITTER: Bauer A 

PROVIDER: S-EPMC6010010 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature