Structures and magnetic properties of two series of Schiff base binuclear lanthanide complexes
Ying Lu, Zhong‐Ming Huang, Hua‐Hong Zou, Fu‐Pei Liang
Abstract
Until now, although there are many examples of studying the magnetic properties of Schiff base binuclear lanthanide complexes, the relationship between the structure and magnetic properties of the complexes still is worth further investigation in order to improve the magnetic properties of Schiff base lanthanide complexes. In this work, we successfully obtained two series of binuclear Ln complexes by in situ reaction of 4‐diethylaminosalicylaldehyde, benzoic hydrazide and different lanthanide salts at 80°C under solvothermal conditions, namely, [Ln 2 (L) 3 (NO 3 ) 3 ]·CH 3 CN·CH 3 OH·H 2 O [Ln = Dy ( 1 ), Ho ( 2 ), Gd ( 3 ) L = deprotonated 4‐diethylamino salicylaldehyde benzoylhydrazine], [Ln 2 (L) 4 (CH 3 COO)]CH 3 COO·CH 3 CN [Ln = Dy ( 4 ), Ho ( 5 ), Gd ( 6 )]. The complex 1 contains three Schiff base ligands L, two Dy (III) ions, and three NO 3 − . The ligand H 1 L is formed by in situ Schiff base reaction with 4‐diethylaminosalicylaldehyde and benzoic hydrazide with the participation of Ln (NO 3 ) 3 . When replacing Ln (NO 3 ) 3 with Ln (OAc) 3 , obtained three μ 2 ‐OAc bridged binuclear Ln (III) complexes. The magnetic study showed that complex 4 exhibits field‐induced single‐molecule magnet (SMM) behavior while complex 1 does not show any SMMs behavior. In addition, we have studied the magnetocaloric effect of complexes 3 and 6 , their maximum −Δ S m values are 21.37 J kg −1 K −1 and 15.32 J kg −1 K −1 , respectively, under Δ H = 7 T and T = 2 K.