Luminescent studies of Ln(III) complexes with 4-amino-6-methylpicolinic acid N-oxide at 77Â K

Spectroscopic properties of Ln(III) complexes with 4-amino-6-methylpicolinic acid N-oxide (ampicN-O) were characterized using absorption, fluorescence and phosphorescence spectra of the ligand as well as Eu(III) luminescence (intensity, lifetime measurements and selective excitation spectra in the range of 5D0←7F0 transition) at 77 and 293 K. Based on emission behavior of ampicN-O and its Eu(III) and Gd(III) complexes the energy level of the ligand triplet state, mechanism of the ligand to metal energy transfer has been proposed and a role of the C-T state in this process analyzed. Detailed studies of the Eu(III) selective excitation spectra in the range of 5D0←7F0 transition recorded for Eu/ampicN-O aqueous solution indicated equilibrium of three complex forms: ML, ML2, ML3.