Syntheses, structures, and photoluminescence of lanthanide coordination polymers with pyridine-2,3,5,6-tetracarboxylic acid

Abstract

Six lanthanide(III) coordination polymers with the formulae {[Ln(Hpdtc)(H₂O)₃]·H₂O}_n [Ln = La (1), Ce (2), Pr (3)], {[Ln(Hpdtc)(H₂O)₂]·2H₂O}_n [Ln = Eu (4), Tb (5)] and {SmK(pdtc)(H₂O)₄}_n (6) (H₄pdtc = pyridine-2,3,5,6-tetracarboxylic acid) have been synthesized by reacting the corresponding rare earth salts or oxides with H₄pdtc under hydrothermal conditions. In the three kinds of structure, H₄pdtc displays three different coordination modes. H₄pdtc is an elegant ligand with rich coordination sites and low symmetry, but has seldom been used to synthesize complexes. 1–6 are the first examples from lanthanide ions and H₄pdtc. Furthermore, the novel wave-like T3(2)4(2)6(2) water tape with (H₂O)₄ as the substructure is present in complex 6. The two complexes of Eu(III) and Tb(III) exhibit the corresponding characteristic luminescence.