Syntheses and characterization of three lanthanide(III) complexes containing pyridine-3,5-dicarboxylic acid and oxalic acid ligands

Abstract

Direct reaction of pyridine-3,5-dicarboxylic acid (H2PDA) and oxalic acid (H2ox) with Ln(ClO4)3 · nH2O under hydrothermal conditions gave three 3-D coordination networks, [Ln(PDA)(ox)0.5(H2O)2] · H2O [Ln = La(1), Nd(2), and Eu(3)]. The complexes were characterized by elemental analysis (EA), X-ray single-crystal diffraction, infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Single crystal X-ray diffractions shows that the compounds are isomorphous and have 3-D framework structures, in which pyridine-3,5-dicarboxylates (PDA2−) link lanthanides to give 2-D layers, which are further fabricated into a 3-D network via bis-bidentate oxalate bridging. Luminescence of 3 is investigated.