Enhancement of luminescence during photolysis of Eu3+ and Tb3+ complexes with acrylic acid-based macromolecular ligands

The fluorescent and photochemical properties of Eu3+ and Tb3+ complexes with macromolecular ligands based on acrylic acid were studied. The photochemical behavior of the macromolecular Ln3+ complexes with acrylic acid – alkyl methacrylate copolymers differs considerably from those Ln3+ complexes with polyacrylic acid and of low-molecular-weight analogs; in the former case, the intensity of Ln3+ photoluminescence noticeably increases during photolysis rather then decreases. The mechanism of the luminescence enhancement in lanthanide macromolecular complexes has been suggested on the basis of the experimental data. The decrease of the relative fraction of monodentate-coordinated carboxylate ions during the macromolecular metal-containing complexes photolysis and increase of the number of acid residues bidentate-cyclic-coordinated to the luminescence center promotes the lanthanide ion luminescence intensification. - Highlights: ► The fluorescent and photochemical properties of Eu3+ and Tb3+ complexes with macromolecular ligands have been studied. ► The mechanism of the luminescence enhancement during photolysis has been suggested. ► The increase of the metal–bidentate ligand conjugation degree promotes luminescence intensification.