Syntheses and characterizations of two lanthanide(III)–copper(II) coordination polymers constructed by pyridine-2,6-dicarboxylic acid

The hydrothermal reaction of La2O3 and Pr2O3 with pyridine-2,6-dicarboxylic acid (H2pydc), CuO, and H2O with a mole ratio of 1:2:4:300 resulted in the formation of two polymeric Cu(II)–Ln(III) complexes, [{Ln4Cu2(pydc)8(H2O)8} · 18H2O]n (Ln = La (1); Pr (2)). 1 and 2 are isomorphous and crystallize in monoclinic space group C2/c. Complexes 1 and 2 have one-dimensional infinite chains with “∞” shape. The 1D chains are linked by the hydrogen bonds and π⋯π stacking interactions to form layer structures which are further linked by the hydrogen bonds and π⋯π stacking interactions to form the three-dimensional (3D) structures with nanoscale porosities. Temperature-dependent magnetic susceptibilities and the thermal stabilities of complexes 1 and 2 were studied.