A Dy4 single-molecule magnet and its Gd(iii), Tb(iii), Ho(iii), and Er(iii) analogues encapsulated by an 8-hydroxyquinoline Schiff base derivative and β-diketonate coligand

Abstract

Five new tetranuclear complexes based on an 8-hydroxyquinoline Schiff base derivative and the β-diketone coligand, [Ln₄(acac)₄L₆(μ₃-OH)₂]·CH₃CN·0.5CH₂Cl₂ (Ln = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5); HL = 5-(benzylidene)amino-8-hydroxyquinoline; acac = acetylacetonate) have been synthesized, and structurally and magnetically characterized. Complexes 1–5 have similar tetranuclear structures. Each Ln^III ion is eight coordinated and its coordination polyhedra can be described as being in a distorted square-antiprismatic geometry. The magnetic studies reveal that 1 features the magnetocaloric effect (MCE) with the magnetic entropy change of −ΔS_m(T) = 25.08 J kg⁻¹ K⁻¹ at 2 K for ΔH = 7 T, and 3 displays the slow magnetic relaxation behavior of Single Molecule Magnets (SMMs) with the anisotropic barrier of 86.20 K and the pre-exponential factor τ₀ = 2.99 × 10⁻⁸ s.