Lanthanide coordination compounds with 2,2′-bipyridine-6,6′-dicarboxylate: Synthesis, crystal structure, luminescence and magnetic property

Abstract

Two types of eleven new lanthanide coordination compounds, namely, {[Na2Ln2(bpdc)4(H2O)2]·3H2O}n, Ln=Gd (1), Tb (2), Dy (3), Ho (4), Er (5), Yb (6), and [Ln(bpdc)(H2O)4][Ln(bpdc)2]·5H2O, Ln=Tb (7), Dy (8), Ho (9), Er (10), Yb (11) (H2bpdc=2,2′-bipyridine-6,6′-dicarboxylic acid) have been synthesized under hydrothermal conditions. Compounds 1–6 formed at higher pH values (5.5–6.5) are isostructural 2D alkali–lanthanide heterometallic coordination polymers, which are simplified as a (3,3,4) network of {3·102}{3·4·5·102·11}{3·4·5}. Compounds 7–11 are obtained at lower pH values (pH=2.0–3.0), and exhibit a discrete structure consisting of one complex cation and one complex anion, which are further extended into 2D metal–organic supramolecular frameworks by O−H⋯O hydrogen bonds. Additionally, the compounds exhibit the characteristic emissions of lanthanide ions in the visible and near-infrared region. Magnetic properties of compounds 1–5 have also been studied.