Two new 3D lanthanide metal-organic frameworks constructed from nitrilotriacetate and oxalate ligands

Two isomorphous three-dimensional lanthanide metal-organic frameworks, K[Ln(2)(NTA)(ox)(2)(H2O)(2)]center dot 3H(2)O (Ln = Pr (1) and Gd (2), NTA = nitrilotriacetate, ox = oxalate) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction, thermogravimetric analysis (TGA) and magnetic analyses. The 3D frameworks of compounds 1 and 2 possess three topologically nonequivalent 4-connected nodes synchronously and exhibit unprecedented (6(5).8) (4(3).6(3))(4.6(5)) topologies. Variable-temperature magnetic susceptibility measurements for complexes 1 and 2 indicate there exist antiferromagnetic interactions between magnetic centers. (C) 2010 Elsevier B.V. All rights reserved.