Syntheses, structure and near-infrared (NIR) luminescence of Er2, Yb2, ErYb of homodinuclear and heterodinuclear lanthanide(iii) complexes based on salen ligand

Abstract

Three dinuclear lanthanide complexes are achieved by using H₂salen or H₂salen/acac ligands (H₂salen = N,N′-ethylenebis(salicylideneimine), acac = acetylacetonate). They are homodinuclear [Er₂(salen)₃] (1), [Yb₂(salen)₂(acac)₂] (2), and heterodinuclear geometrical [ErYb(salen)₂(acac)₂] (3). The structures of complexes were determined by single crystal X-ray crystallographic studies and their photophysical properties were investigated. The homonuclear Yb₂ complex exhibits characteristic metal-centered NIR emission. The geometric ErYb isomer exhibits ‘dual emissions’ from both erbium(III) and ytterbium(III) ions. There was no detectable photoluminescence in the Er₂ complex, not only in solid state but also in solvent.