Spectroscopic behaviour of lanthanide(_III) coordination compounds with Schiff base ligands

The spectroscopic properties of lanthanide(III) complexes with Schiff base ligands (substituted salicylaldimines) are described. Optical absorption spectra of Nd(III), Ho(III) and Er(III) complexes dissolved in chloroform were recorded. The dipole strengths of the transitions were determined experimentally and parameterised in terms of three phenomenological Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6). The complexes exhibit unusually intense hypersensitive transitions. The intensity enhancement can be attributed to the highly polarisable ligands and to the low site symmetry around the lanthanide ions (C1). The luminescence spectra of Eu(III) compounds were measured, but the emission intensities were low