Syntheses, Crystal Structures, and Luminescence Properties of a Series of Novel Lanthanide Oxalatophosphonates with Two Types of 3D Framework Structures

By introduction of oxalate as the second ligand, 12 novel lanthanide oxalatophosphonates with two types of three-dimensional (3D) framework structures, namely, [Ln(2)(H4L)(C2O4)(3)(H2O)] center dot 3H(2)O (Ln = La (1), Cc (2), Pr(3), Nd (4), Sm (5), Eu (6), H4L = 3-pyridyl-CH2N(CH2PO3H2)(2)) and [Ln(2)(H4L)(C2O4)(3)(H2O)] center dot 2H(2)O (Ln = Gd (7), Tb (8) Dy (9) Y (10), Er (11), Lu (12)), have been synthesized under hydrothermal conditions. Compounds 1-6 are isostructural and Feature a 3D framework structure formed by the interconnection of the 3D network of {Ln(2)(C2O4)(3)} with one-dimensional chains of {Ln(2)(H4L)}(6+). Compounds 7-12 are also isostructural and possess a novel 3D Framework Structure different from that in compounds 1-6. The interconnection of Ln(III) ions by chelating and bridging oxalate anions result in I lanthanide oxalate layer in the ac planes. These layers are further linked by H4L ligands to form it 3D framework. It is interesting that a type of right hand helical chain is formed by H4L ligands bridging Er(2) ions running along the b-axis. The Nd, Eu, and Tb compounds exhibit strong luminescence in near-IR, red light, and green light regions, respectively.