Probing the magnetic relaxation and magnetic moment arrangement in a series of Dy4 squares

Abstract

Three μ₄-O bridged Dy₄ squares, {[Dy₄(μ₄-O)(HL¹)₄(H₂O)₄]₂(NO₃)₃(OH)}·2H₂O·2CH₃OH (1), [Dy₄(μ₄-O)(HL²)₄(SCN)₂]·2H₂O·4CH₃OH (2) and [Dy₄(μ₄-O)(H₂L³)₂(SCN)₂]·6H₂O (3) were assembled by using a Schiff base ligand and its dimerized and reduced congener, respectively. These complexes share a similar μ₄-O bridged Dy₄ core, while, both the coordination geometry and metal–ligand interactions are slightly changed upon the modulation of the ligands, resulting in distinct single-molecular magnetic (SMM) and single-molecular toroic (SMT) properties. In complex 1, the Schiff base ligands are in an antiparallel fashion and all Dy^III ions are in a similar coordination geometry, realizing the toroidal arrangement of magnetic moments. For complex 2, the reduced ligand H₃L² in a parallel fashion results in double relaxation processes and a 9-fold increase of the U_eff. Interestingly, with the use of the dimerized ligand H₆L³, we obtained complex 3, which is similar to complex 2, while due to the slight changes of the coordination environment both the single molecular magnetic property and toroidal magnetic moments almost disappeared.