Interaction of TbCl3 and lanthanide complexes with poly(N-vinylpyrrolidone)

The interaction of TbCl3 and lanthanide(III) beta-diketonate complexes with poly(N-vinylpyrrolidone) (PVP) polymer was studied using fluorescence spectroscopy. In the presence of PVP the emission of Tb3+ in ethanolic solution of TbCl3 significantly increased owing to the excitation energy transfer from PVP to Tb3+ ions, which was more efficient as compared to a direct excitation of the Tb3+ 4f(7)5d(1) levels. In contrast, emission of NEt4Tb(hfa)(4) and NEt4Eu(hfa)(4) complexes was almost completely quenched in solution containing PVP. The PVP bound both Ln(3+) ions and hfa ligands which caused decomposition of Ln-hfa complexes and switched off the excitation energy transfer from the ligand to the emitting Ln(3+) ion. The important role of hydrogen bonds in stabilization of interaction of hfa ligands with PVP was indicated.