Development and Comparative Study of a Hydrophilic Bis-Triazolyl-Phenanthroline and Two Bis-Triazolyl-Pyridine Ligands

Abstract

A comprehensive study of three novel hydrophilic CHON-compliant ligands, two hydrophilized with longer diethylene glycol chains (DEG-BTrzPhen and DEG-PTD) and one with shorter hydroxyethyl chains (HE-PTD), encompassing synthesis, solubility, solvent extraction, coordination, spectral, crystallographic and computational studies is presented herein. Experimental results demonstrated that under weakly acidic conditions, these ligands exhibited selectivity for Am(III) vs. Eu(III), with maximum separation factors (SF_Eu/Am) reaching 74, 240, and 127 for DEG-BTrzPhen, DEG-PTD, and HE-PTD, respectively. Among these ligands, DEG-PTD, a derivative of the well-known PTD, exhibits exceptionally high aqueous solubility, offering a significant technological advantage. With its overall characteristics, being CHON-compliant, selective, cheap, and with high aqueous solubility even at very high concentrations, the DEG-PTD ligand is a viable option for actual industrial applications.