Syntheses, structural modulation, and slow magnetic relaxation of three dysprosium(III) complexes with mononuclear, dinuclear, and one-dimensional structures.

Three mononuclear, dinuclear and one-dimensional dysprosium(III) complexes based on 3-azotriazolyl-2,6-dihydroxybenzoic acid (H4ATB) of [Dy(H3ATB)3]·3H2O (1), [Dy2(H2ATB)2(H2DHB)2(H2O)4]·2CH3CN·5H2O (2), and [Dy2(H2ATB)2(DCB)(DMF)2(H2O)2]·4DMF (3) were synthesized and structurally characterized by X-ray single crystal diffraction (H3DHB = 2,6-dihydroxybenzoic acid, H2DCB = 1,4-dicarboxybenzene). Complex 1 was used as a precursor to synthesize complexes 2 and 3, and 2 was further used to synthesize 3. Complex 1 is a mononuclear complex, in which the Dy(III) ion is in a nine-coordinated structure surrounded by three tridentate chelate H3ATB- ligands. Complex 2 displays a dinuclear structure bridged by two μ2 carboxyl groups of two H2DHB- ligands and two μ1,1-O atoms from the phenolic hydroxyl groups of two H2ATB2- ligands. Complex 3 shows a one-dimensional structure formed by two bridging DCB2- ligands. The magnetic measurements were performed on three complexes 1-3, and they showed different magnetic behavior. Complex 1 shows a field-induced slow magnetic relaxation. Complexes 2 and 3 display distinct slow magnetic relaxation under zero dc field with energy barriers (Ueff) of 26(2) cm-1 and 11(1) cm-1, respectively. The magnetic behavior of three complexes 1-3 was investigated by ab initio calculations.