Novel 3-Ethoxysalicylaldehyde Lanthanide Complexes Obtained by Decomposition of Salen-Type Ligands

Three new asymmetrically coordinated lanthanide derivatives based on the bicompartmental salen-type ligands N,N′-bis(3-ethoxysalicylidene)propylene-1,3-diamine (H2EtOsalpr) and 3-ethoxysalicylaldehyde (HEtvain) have been synthesized and structurally and photophysically characterized. All the compounds show dimeric structures of the general formula [Ln(H2EtOsalpr)(NO3)2(Etvain)]2 (Ln = Nd, Eu, Dy), with each salen-type ligand bridging two lanthanide ions. The Etvain ligand comes from the H2EtOsalpr decomposition being coordinated to the corresponding lanthanide. The Nd(III) derivative shows fluorescence emission in the NIR region, but for the Eu(III) and Dy(III) compounds, only a broad band, attributed to the ligand emission, was observed.