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

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)( mu 2-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 CuII ions into a one-dimensional (1D) loop chain, and the suc anions link the LnIII 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).