Water-Soluble Polymeric Heteroligand Europium Complexes

Abstract

Water-soluble polymeric complexones, N-vinylpyrrolidone-N-allyl-p-aminosalicylic acid copolymers with low content of chelating units, were synthesized. The formation of Eu³⁺ heteroligand complexes containing these complexones was studied. The complexation of Eu³⁺ with the polymeric complexone and low-molecular-mass organic coligand, thenoyltrifluoroacetone (TTA), ensures efficient energy transfer from molecular orbitals of the polymeric ligand to Eu³⁺, allowing the Eu³⁺ luminescence intensity in aqueous solutions to be enhanced by more than 1–1.5 orders of magnitude. The maximal intensity of the Eu³⁺ luminescence in the heteroligand complex is observed at the [Eu³⁺]:[COO⁻] ratio of ∼1 and [Eu³⁺]/[TTA] = 1.2−1.5. In the presence of univalent metal salts, the Eu³⁺ luminescence intensity does not noticeably change up to their concentration of 0.4 M. Addition of Ca²⁺ or Mg²⁺ salts leads to a drastic decrease in the Eu³⁺ luminescence intensity in the solution.