Lanthanide Complexes Of Pyridine Carboxylic Acids Synthesis, Structure And Performance Studies

In this article, reactions of 3-pyridin-3-yl-benzoic acid (HL1) and 3-pyridin-3-yl-benzoic acid (HL2) with rare earth nitrate under hydrothermal conditions yield eight new coordination polymers. Ln₂(L1)₆(H₂O)₄ [Ln = Sm (1), Tb (2)], Ln(L2)₄(H₂O)₂·H₂O [Ln = Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Er (8)]. TGA, IR, X-ray powder diffraction and X-ray crysrallographic analyses were carried out for these eight complexes. Fluorescent and magnetic properties were also studied.1 and 3–8 were in the triclinic space group P–1. The structure of complexes and 3–8 were 1D chain structure. In the adjacent 1D chain exitedπ–πaccumulation. In complexes, rare earth ions were all eight coordinated. The fundamental unit of complex1 was made from two rare earth ion centers while complexes 3–8 only had one rare earth ion center. Crystallographic data reveals that compounds 3–8 were isomorphous. TGA analysis indicated that the metal-organic framework decomposition temperature of complexes 1–8 exceed 400°C. Complexes 2, 5 and 7 showed the characteristic Ln(III) luminescence in the visible region and researched the mechanism, and their fluorescence life values were 715.80, 386.18 and 637.47μs. Fluorescence values of these complexes were first studied. Magnetic strudy of 6 showed that it exhibited antiferromagnetic behavior.