Density functional complexation study of metal ions with poly(carboxylic acid) ligands. Part 2. Poly(acrylic acid- co-maleic acid), poly(methyl vinyl ether- co-maleic acid), and poly(epoxy succinic acid)

Abstract

We have studied metal ion complexation with poly(carboxylic acid) ligands using density functional methods and a continuum-solvation model (COSMO). Geometry optimisations have been carried out for metal complexes of poly(acrylic acid- co-maleic acid), poly(methyl vinyl ether- co-maleic acid), and poly(epoxy succinic acid) oligomers. The complexation energies for Mg 2+, Ca 2+, Mn 2+, and Fe 3+ have been calculated and they have been corrected with previously determined metal specific correction parameters. The most effective ligand for all the metal ions was found to be poly(epoxy succinic acid). With Ca 2+, poly(epoxy succinic acid) was found to form 6-coordinated complex with three metal-coordinating carboxylate oxygen, two ether oxygens, and one hydroxyl oxygen atom. All the other metals favoured 5-coordinated complexation geometry with four metal-coordinating carboxyl oxygens and one ether oxygen atom.