Magnetic properties and structure of tetranuclear lanthanide complexes based on 8-hydroxylquinoline Schiff base derivative and β-diketone coligand.

Five tetranuclear lanthanide complexes [Gd(dbm)(L)(μ-OH)]·5CHCN (1), [Tb(dbm)(L)(μ-OH)]·2CHCHOH·4CHCN (2), [Dy(dbm)(L)(μ-OH)]·4CHCN·2HO (3), [Ho(dbm)(L)(μ-OH)]·CHCHOH·4CHCN·2HO (4) and [Er(dbm)(L)(μ-OH)] (5) are obtained from the reaction of 5-(4-pyridinecarboxaldehyde)amino-8-hydroxylquinoline (HL) and Ln(dbm)·2HO (dbm = 1,3-diphenyl-1,3-propanedione). Complexes 1-5 are isomorphous and crystallize in the monoclinic space group P2/c. The metal ions in 1-5 adopt an approximately square-antiprismatic coordination environment. Magnetic studies indicate that complex 1 features a magnetocaloric effect (MCE) with the magnetic entropy change of -ΔS(T) = 16.35 J kg K at 3 K for ΔH = 7 T. Additionally, complex 3 displays single molecule magnet (SMM) behavior, exhibiting an effective energy barrier of the relaxation of magnetization U/k = 89.38 K and pre-exponential factor τ = 3.32 × 10 s.