Complexation of europium using polyethylene carboxylic acid

Abstract

Competitive complexation of europium(III) carboxylates by an octadecanoic carboxylate and a terminally functionalized oligomeric ethylene carboxylate ( M n = ∼ 1500–2000) showed that there was little difference between a low molecular weight alkyl carboxylate ligand and an oligomeric polyethylene carboxylate ligand in their interaction with a metal salt in a toluene solution at 105°C. The most significant difference between these two carboxylate ligands was the facility with which the oligomeric carboxylate removes europium(III) from solution when the oligomer and octadecanoate were present at comparable concentrations. Comparison of calculations and experimental values for the amount of europium left in solution after equilibration of various ratios of terminally carboxylated oligomeric polyethylene and octadecanoic acids with europium(III) was used to evaluate the relative ligating ability of a soluble macromolecular and octadecyl carboxylate for europium(III) in toluene. Use of a less well-defined oxidized polyethylene instead of well-characterized terminally carboxylated oligomers as ligands had little effect on these equilibria. Experiments also showed that the solubility of these oligomerically ligated europium salts changed significantly over a temperature range of 60–85°C.