Lanthanide Complexes of a Calix[4]arene Ligand with Dangling Phosphonate and Picolinamide Arms: Synthesis, Crystal Structures, and Extraction Properties

Artificial phosphatase upon premicellar nanoarchitectonics of lanthanum complexes with long-chained imidazole derivatives

Four novel long chain-containing tridentate imidazole derivatives (Lⁿ, n = 1, 2, 3, 4) were synthesized for in situ formation of mononuclear lanthanum(III) complexes as artificial phosphodiesterases. These in-situ formed La(III) complexes (named LaLⁿ) were used to catalyze the transesterification of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP), a classic RNA model. Critical aggregation concentrations (CAC) were determined for the as-prepared tridentate imidazole derivatives as ligands and corresponding mixtures of equivalent ligand and La³⁺ ion with a mole rate of 1:1. It denotes that the introduction of La³⁺ ion increases the CAC values of imidazole derivatives by about 2 to 3 folds. Foaming test shows that the foam height is positively correlated with the length of hydrophobic chain. Transesterification of HPNP mediated by LaLⁿ nanoarchitectonics indicates that the introducing of hydrophobic chain benefits rate enhancement, showing excess three orders of magnitude acceleration under physiological conditions (pH 7.0, 25 °C). Moreover, catalytic reactivities of these La(III) complexes increased along with the increase in chain length: LaL¹ < LaL² < LaL³ < LaL⁴, suggesting a positive correlation to hydrophobic chain length.

Tetra-substituted p-tert-butylcalix[4]arene with phosphoryl and salicylamide functional groups: synthesis, complexation and selective extraction of f-element cations

A new series of lanthanide ( 1-5 ) and uranyl ( 6 ) complexes with a tetra-substituted bifunctional calixarene ligand H 2 L is described. The coordination environment for the Ln 3+ and UO 2 2+ ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert -butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La 3+ , Pr 3+ ; intermediate: Eu 3+ and Gd 3+ ; and heavy: Yb 3+ ), as well as the uranyl cation (UO 2 2+ ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2:2 M: L , [Ln 2 ( L ) 2 (H 2 O)] 2+ ( 1 - 5 ), in solution, whereas uranyl formed a 1:1 M: L complex [UO 2 ( L )(MeOH)] ∞ ( 6 ) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H 2 L was found to be an effective extracting agent for UO 2 2+ over La 3+ and Yb 3+ cations. The separation factors at pH 6.0 are: [[EQUATION]] = 121.0 and [[EQUATION]] = 70.0.

Perspectives of multiscale rare earth crystal materials

Both multisize and multiweight effects are proposed to characterize multiscale rare earth crystal materials.

Dinuclear lanthanide complexes supported by a hybrid salicylaldiminato/calix[4]arene-ligand: synthesis, structure, and magnetic and luminescence properties of (HNEt3)[Ln2(HL)(L)] (Ln = SmIII, EuIII, GdIII, TbIII)

Salicylaldimine/calix[4]arenes support dinuclear, triply bridged, luminescent, lanthanide complexes.

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

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 [ΔH1:1=(-71.5±10.0) kJ mol-1; TΔS1:1=(-37.57±10.0) kJ mol-1], whereas the second complexation step was found to be endothermic and entropy driven [ΔH2:1=(32.8±4.0) kJ mol-1; TΔS2:1=(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.