Structure Activity Relationship Approach toward the Improved Separation of Rare-Earth Elements Using Diglycolamides.

The separation of adjacent lanthanides continues to be a challenge worldwide because of the similar physical and chemical properties of these elements and a necessity to advance the use of clean-energy applications. Herein, a systematic structure-performance relationship approach toward understanding the effect of -alkyl group characteristics in diglycolamides (DGAs) on the separation of lanthanides(III) from a hydrochloric acid medium is presented. In addition to the three most extensively studied DGA complexants [,,','-tetra(-octyl)diglycolamide, TODGA; ,,','-tetra(2-ethylhexyl)diglycolamide, TEHDGA; ,'-dimethyl-,'-di(-octyl)diglycolamide, DMDODGA], 12 new extracting agents with varying substitution patterns were designed to study the interplay of steric and electronic effects that control rare-earth element extraction.

Efficient Separation of Light Lanthanides(III) by Using Bis-Lactam Phenanthroline Ligands.

Due to the ever-increasing demand for high-purity individual rare-earth elements, novel and highly selective separation processes are increasingly sought after. Herein, we report a separation protocol that employs shape-persistent 2,9-bis-lactam-1,10-phenanthroline (BLPhen) ligands exhibiting unparalleled selectivity for light trivalent lanthanides. The highly preorganised binding pockets of the ligands allowed for the separation of lanthanides with high fidelity, even in the presence of competing transition metals, in a biphasic separation system.

Contributions of inner and outer coordination sphere bonding in determining the strength of substituted phenolic pyrazoles as copper extractants.

Alkyl-substituted phenolic pyrazoles such as 4-methyl-2-[5-(n-octyl)-1H-pyrazol-3-yl]phenol (L2H) are shown to function as Cu-extractants, having similar strength and selectivity over Fe(iii) to 5-nonylsalicylaldoxime which is a component of the commercially used ACORGA® solvent extraction reagents. Substitution in the phenol ring of the new extractants has a major effect on their strength, e.g.

EPR/ENDOR and Computational Study of Outer Sphere Interactions in Copper Complexes of Phenolic Oximes.

Copper complexes of the phenolic oxime family of ligands (3-X-salicylaldoximes) are used extensively as metal solvent extractants. Incorporation of electronegative substituents in the 3-position, ortho to the phenol group, can be used to buttress the interligand H-bonding, leading to an enhancement in extractant strength. However, investigation of the relevant H-bonding in these complexes can be exceedingly difficult.

Assessing the performance of density functional theory in optimizing molecular crystal structure parameters.

This paper assesses the performance of plane-wave density functional theory calculations at returning reliable structural information for molecular crystal structures where the primary intermolecular interactions are either hydrogen bonding or dispersion interactions. The computed structures are compared with input structures obtained from the Cambridge Structural Database, and assessed in terms of crystal packing similarities, unit-cell volume and shape, short contact distances and hydrogen-bond distances. The results demonstrate that the PBE functional [Perdew, Burke & Ernzerhof (1996).