Hydrothermal synthesis and luminescence of lanthanide complexes sensitized with dpphen

Abstract

Three new lanthanide complexes [Ln(dpphen)(L)(NO3)] (Ln=Tb(1), Eu(2), Nd(3), H2L=glutaric acid, dpphen=4,7-diphenyl-1,10-phenanthroline) have been synthesized hydrothermally by the reaction of H2L, dpphen and Ln(III) ions. The X-ray diffraction analysis reveals that three coordination polymers have similar structures. The Ln(III) ions are nine coordinated and glutarate ligands bridge Ln(III) to form 1D polymer chains. The solid-state luminescence of complexes 1 and 2 was investigated at room temperature. The complexes 1 and 2 exhibited strong green and red luminescence under ultraviolet light. The 5D4→7Fj (j=6, 5, 4 and 3) transition emissions of Tb(III) and the 5D0→7Fj (j=0–4) transition emissions of Eu(III) were observed in their emission spectra. The strong luminescence of complexes 1 and 2 demonstrates that luminescence of lanthanide coordination polymers is sensitized by an effective energy-transfer from dpphen ligand to Ln(III) ions. Moreover, the magnetic properties of complexes 1–3 were also investigated.