A series of novel lanthanide carboxyphosphonates with a 3D framework structure: synthesis, structure, and luminescent and magnetic properties

Abstract

By introduction of 1,4-benzenedicarboxylic acid as the second organic ligand, a series of novel lanthanide carboxyphosphonates with a 3D framework structure, namely, [Ln₃(H₂L)(HL)₂(bdc)₂(H₂O)]·7H₂O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8); H₃L = H₂O₃PCH₂NC₅H₉COOH; H₂bdc = HOOCC₆H₄COOH) have been synthesized under hydrothermal conditions. Compounds 1–8 are isostructural and feature a 3D framework in which Ln(III) polyhedra are interconnected by bridging {CPO₃} tetrahedra into 2D inorganic layers parallel to the ab plane. The organic groups of H₂L⁻ are grafted on the two sides of the layer. These layers are further cross-linked by the bdc²⁻ ligands from one layer to the Ln atoms from the other into a pillared-layered architecture with one-dimensional channel system along the a axis. The thermal stability of compounds 1–8 has been investigated. Luminescent properties of compounds 5–8, and the magnetic properties of compound 8 have also been studied.