Tuning aminopolycarboxylate chelators for efficient complexation of trivalent actinides

CD Pilgrim and TS Grimes and C Smith and CR Heathman and J Mathew and S Jansone-Popova and S Roy and D Ray and VS Bryantsev and PR Zalupski, SCIENTIFIC REPORTS, 13, 17855 (2023).

DOI: 10.1038/s41598-023-44106-6

The complexation of trivalent lanthanides and minor actinides (Am3+, Cm3+, and Cf3+) by the acyclic aminopolycarboxylate chelators 6,6 '- ((ethane-1,2-diylbis-((carboxymethyl)azanediyl))bis- (methylene))dipicolinic acid (H(4)octapa) and 6,6'-((((4-(1-(2-(2-(2- hydroxyethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)pyridine-2,6-diyl)bis- (methylene))bis-((carboxymethyl)azanediyl))bis-(methylene)) dipicolinic acid (H(4)pypa-peg) were studied using potentiometry, spectroscopy, competitive complexation liquid-liquid extraction, and ab initio molecular dynamics simulations. Two studied reagents are strong multidentate chelators, well-suited for applications seeking radiometal coordination for in-vivo delivery and f-element isolation. The previously reported H(4)octapa forms a compact coordination packet, while H(4)pypa-peg is less sterically constrained due to the presence of central pyridine ring. The solubility of H(4)octapa is limited in a non- complexing high ionic strength perchlorate media. However, the introduction of a polyethylene glycol group in H(4)pypa-peg increased the solubility without influencing its ability to complex the lanthanides and minor actinides in solution.

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