LnIII2 compounds constructing by polydentate Schiff base ligand and β-diketonate coligand: structures, magnetocaloric effect and SMMs behaviors

Four new Ln III 2 compounds [Ln 2 (dbm) 2 (L) 2 (CH 3 OH)] (Ln(III) = Gd ( 1 ), Tb ( 2 ), Ho ( 3 ), and Tm ( 4 )), where H 2 L is 2-hydroxyamino-propionic acid (3,5-di- tert -butyl-2-hydroxy-benzylidene)-hydrazide and Hdbm is dibenzoylmethane, were successfully synthesized via solvothermal   method and characterized structurally and magnetically. Magnetic studies reveal the anti-ferromagnetic interaction was existed in compound 1 . Moreover, magnetic refrigeration property study suggests that compound 1 exhibits magnetocaloric effect with − Δ S m  = 21.07 J kg −1 K −1 for Δ H  = 7.0 T at 2.0 K. Alternating-current (ac) magnetic susceptibility study of 2 and 3 suggests that single-molecule magnet (SMM) behavior occurs for 2 and 3 under H dc  = 0 Oe with the effective energy barrier Δ E / k B of 20.05 K and τ 0 of 2.93 × 10 −6 s for 2 and Δ E / k B  = 0.85 K and τ 0  = 3.47 × 10 −5 s for 3 .