The structurally rigid tetradentate N,N′,O,O′-ligands based on phenanthroline for binding of f-elements: The substituents vs. structures of the complexes

Abstract

Abstract A new tetradentate N,N′,O,O′-ligands possessing fixed preorganised conformation geometry for metal ion binding are proposed and effectively synthesised. The interaction of the ligands with nitrates of 4f-elements was studied and the complexes were readily prepared. Their structures were studied by various spectroscopic techniques as well as X-ray crystallography. The structures of the lanthanide complexes in comparison with the structure of 5f-element complexes were discussed to illustrate the selectivity of phenanthroline based diamides towards actinides. The influence both of the substituents on the phenanthroline ring and the amidic moiety of the diamides on structures of the complexes is discussed. Several suggestions concerning the rational design of the selective americium extractants based on a phenanthroline scaffold were made starting from structures of the complexes.