Synthesis, crystal structures and luminescent properties of an isotypic series of rare-earths complexes with a dialdehyde ligand

摘要

A series of mononuclear complexes based on lanthanide ions has been synthesized and X-ray characterized. The compounds [Ln~(III)L _2(NO_3)_3(H_2O)_2] (Ln = La, Ce, Pr, Nd, Sm, Gd and Tm; L = 2, 6-bis(2-formylphenoxymethyl)pyridine) are found to be isomorphous and isostructural. Ligand L systematically coordinates through one carbonyl functionality, and the resulting complexes are placed on a twofold axis in crystals belonging to C2/c space-group. Emission spectra for Ln = La, Pr, Nd revealed a correlation between the Ln-O coordination bond length and the photoluminescent properties of the complexes, in line with a F?rster-Dexter mechanism for intramolecular energy transfer. Ligand L is therefore a suitable sensitizer for lanthanide ions.