Syntheses, structures, and magnetic properties of two series of copper-lanthanide heterometallic coordination polymers based on pyridine-2,3-dicarboxylic acid and succinic acid

Abstract

Two series of copper-lanthanide heterometallic coordination polymers (CPs), [LnCu(2,3-pydc)₂(suc)_0.5(H₂O)₃]·H₂O [Ln = La (I), Pr (II), Nd (III), Sm (IV), Gd (V), and Eu (VI), 2,3-H₂pydc = pyridine-2,3-dicarboxylic acid, H₂suc = succinic acid], [Ln₂Cu₃(2,3-pydc)₆(H₂O)₁₀]·8H₂O [Ln = Eu (VII), Tb (VIII), Dy (IX), and Er (X)], [Ln₂Cu(2,3-pydc)₂(suc)(μ₂-OH)₂(H₂O)₂]·2H₂O [Ln = Er (XI), Yb (XII), and Lu (XIII)], [Ln₂Cu(2,3-pydc)₂(suc)₂(H₂O)₆]·2H₂O [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), and Er (6)], and Ln₂Cu(2,3-pydc)₂(suc)₂(H₂O)₂ [Ln = Er (7), Yb (8), and Lu (9)], were successfully synthesized by the hydrothermal reactions of Cu(NO₃)₂·3H₂O, LnCl₃·nH₂O, 2,3-H₂pydc, and H₂suc. CPs 1–9 show two types of similar two-dimensional (2D) structures. In 1–9, the 2,3-pydc anions bridge the Cu^II ions into a one-dimensional (1D) loop chain, and the suc anions link the Ln^III ions into a 1D double chain. The 1D loop chains and the 1D double chains connect each other to generate a 2D layer. The adjacent 2D layers are further packed into a three-dimensional (3D) supramolecular architecture by hydrogen-bonding interactions. CPs 4 and 6 display ferromagnetic interactions between the paramagnetic centers, and CP 5 shows a field-induced slow magnetic relaxation behavior. The structures and magnetic properties of I–XIII have been reported in previous work (Eur. J. Inorg. Chem., 2016, 1060).