Authors
Shi Lin Zhang, Lu Yu, Yong Qiang Wan, Yang-Yang Zhang, Huai Xin Hao, Zhi Peng Wang, John F Gallagher, Jun Li, Pavle Mocilac
Published in
Inorganic chemistry. Volume 65. Issue 43. Pages 25315-25333. Nov 02, 2026.
Abstract
We report the synthesis and evaluation of two CHON-compliant 4,7-dimethoxy-1,10-phenanthroline-2,9-dicarboxamide (DADOMePhen) ligands: an aromatic variant, Et-Tol-DADOMePhen (1), and an aliphatic analogue, TCH-DADOMePhen (2). Solvent extraction under SANEX conditions shows that ligand 1 has good Am/Eu selectivity in an optimal window of 0.1-0.5 M HNO3, achieving a maximum SFAm/Eu of 108.2 at 0.5 M HNO3, the highest reported for a lipophilic ligand of pure DAPhen-type molecular architecture to date. This performance inverts conventional acidity dependence: electron-donating methoxy substituents enhance metal-ligand covalency at low acidity but make the ligand susceptible to protonation at higher concentrations. Coordination and fluorescence studies indicate a 1:2 metal-to-ligand stoichiometry; single-crystal diffraction reveals the structure of ligand 1. Quantum-chemical calculations establish that methoxy groups tune electrostatic potential and frontier orbitals, strengthening bonding relative to parent Et-Tol-DAPhen. Beyond Am/Eu partitioning, ligand 1 may enable actinide/neptunium separations: at 0.1 M HNO3, calculated SFAm/Np, SFPu/Np, SFU/Np, and SFTh/Np reach 436, 1690, 9766, and 1953, respectively, reflecting mismatch between the dioxo Np(V) monocation and the ligand. This work establishes 4,7-methoxy derivatization as a design strategy to tune DAPhen-based extractant selectivity and introduces a ligand that could be useful for specialized low-acidity actinide/neptunium or lanthanide separations.
PMID:
42969533
Bibliographic data and abstract were imported from PubMed on 02 Nov 2026.
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