Magnetic Properties Of Rare Earth Complexes Based On Pyridine Carboxylic Acid Ligands

Based on ligands of isonicotinic acid N-oxide (HINO),5-hydroxynicotinic acid (H2NA) and (4-pyridylthio)acetic acid (HPA),23new lanthanide complexes have been synthesized, whose structures and properties were characterized by elemental analysis, powder X-ray diffraction, ICP-AES, direct-current (dc) magnetic susceptibilities and alternating-current (ac) magnetic susceptibilities.A series of3D framework complexes were obtained with DyⅢ ions, HINO and corresponding solvents. Magnetic properties of these complexes were affected by the type of guest solvents, as illustrated by magnetic measurements. The variation of magnetic properties mainly came from the change of the ferromagnetic interaction between dinuclear dysprosium units due to the calculation results through program CONDON. This is the first observation of lanthanide framework complexes exhibiting magnetic response and slow relaxtion of magnetization toward solvent molecules. Unusual hexa-coordinated lanthanide complexes with H2NA as ligand have been obtained and structurally characterized by hydrothermal method, which show the first examples for syntheses of such stable complexes from water solution. Interesting superparamagnetic behavior was observed from these2D complexes, and the results of calculation and Y-diluted experiments confirmed that the slow relaxation of the magnetization originated from the single-ion anisotropy of DyⅢ ions. A series of new HPA ligated complexes containing polar space group and1D lanthanide chains were synthesized and characterized, the Dy complex showed slow relaxation of magnetization under the given dc field.