Larger magnetocaloric effect and single molecule magnet behavior in dinuclear Ln(III)-based compounds constructed from Schiff base ligand

Abstract

A series of Ln(III)-based compounds with the formula [Ln2(HL)2(acac)2(CH3OH)2] (Ln (III) = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5), Hacac = acetylacetone, H3L = 3-hydroxy-N’-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]pyridine-2-carbohydrazide) based on a flexible Schiff base ligand H3L have been successfully synthesized, and the structures and magnetic properties of 1–5 have been systematacially studied. The crystal structures study indicates that compounds 1–5 are isostructural and possess a parallelogram Ln2O2 core. Magnetic properties measurements reveal that an antiferromagnetic interaction is exsisted in 1 and ferromagnetic interactions are exsisted in compounds 3 and 4. Remarkably, compound 1 displays well cryogenic magnetic refrigeration property with a larger magnetic entropy (−ΔSm = 28.79 J K−1 kg−1, T = 2.0 K and ΔH = 70 kOe). Moreover, alternating-current (ac) magnetic susceptibility research reveals that compound 3 shows slow magnetic relaxation behavior under zero dc field. Furthermore, under an external dc field of 1500 Oe, compound 3 displays remarkable SMM behavior with the effective barrier (ΔE/kB) of 14.9 K.