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

Five tetranuclear lanthanide complexes [Gd4(dbm)4(L)6(μ3-OH)2]·5CH3CN (1), [Tb4(dbm)4(L)6(μ3-OH)2]·2CH3CH2OH·4CH3CN (2), [Dy4(dbm)4(L)6(μ3-OH)2]·4CH3CN·2H2O (3), [Ho4(dbm)4(L)6(μ3-OH)2]·CH3CH2OH·4CH3CN·2H2O (4) and [Er4(dbm)4(L)6(μ3-OH)2] (5) are obtained from the reaction of 5-(4-pyridinecarboxaldehyde)amino-8-hydroxylquinoline (HL) and Ln(dbm)3·2H2O (dbm = 1,3-diphenyl-1,3-propanedione). Complexes 1–5 are isomorphous and crystallize in the monoclinic space group P21/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 −ΔSm(T) = 16.35 J kg−1 K−1 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 Ueff/kB = 89.38 K and pre-exponential factor τ0 = 3.32 × 10−8 s.