Coordinating properties of polymers with N-substituted diamides of malonicacid towards Cu(II); EPR studies

New chelating resins containing N-substituted diamides of malonic acid have been contacted with various Cu(II) solutions and the structural parameters of complexes formed have been investigated using the EPR method. Correlati on between EPR spectra obtained and Cu(II) uptake shows that two main facto rs are influencing the ability of the ligand to coordinate metal ion. The f irst is the length of the pendant group (distance from the backbone chain) facilitating ligand accessibility and the second is the ligand potential to create a chelate ring with Cu(II). This effect is dominant in resins with N-substituted diamides of malonic acid, in which neighbouring ligands can c ooperate efficiently. At higher pH, unusually stable Cu(II) complexes are f ormed by resins with 2-aminoethyl and 2-aminomethylpyridine substituted dia mides of malonic acid due to the involvement of deprotonated amide nitrogen and formation of tetradentate ligands. (C) 1999 Elsevier Science Ltd. All rights reserved.