Syntheses, structure and photoluminescent properties of lanthanide oxalatosulfocarboxylate coordination polymers

Hydrothermal reactions of oxalic acid (H(2)ox) and 2-sulfobenzoic acid (H2L) with lanthanide oxide or hydroxide yielded five lanthanide oxalatosulfocarboxylates. They have a general formula [Ln(2)L(2)(ox)(H2O)(6)] (n) [Ln = La (1), Nd (2), Eu (3), Gd (4), Tb (5)]. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), infrared (IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis (TGA). 1-5 are isostructural coordination polymers and feature one-dimensional (1D) chains, which are extended into 3D supramolecular frameworks through inter-chain hydrogen bonds between coordinated H2O donors and oxygen acceptors from carboxylate, sulfonate and oxalate groups. In addition, the solid-state photoluminescence properties of the Nd (2), Eu (3) and Tb (5) derivatives have been measured at room temperature. The Eu and Tb-containing coordination polymers (CPs) exhibit intense red and green luminescence emissions, respectively, with lifetimes in the order of millisecond.