Modulating Magnetic Properties of Dimer Dysprosium Compounds with Aromatic Organic Molecule Ligands

Four relevant dimer dysprosium compounds, namely, [Dy2(OAc)6(H2O)2]·4H2O (1), [Dy2(OAc)6(L1)2] (2), [Dy2 (OAc)6(L2)2] (3) and [Dy2(OAc)6(L3)2]·2CHCl3 (4) and their corresponding YIII diluted analogues [Dy0.22Y1.78 (OAc)6(H2O)2]·4H2O (1@Y), [Dy0.23Y1.77(OAc)6(L1)2] (2@Y), [Dy0.23Y1.77(OAc)6(L2)2]·2CH3OH (3@Y), and [Dy0.22Y1.78(OAc)6(L3)2]·2CHCl3 (4@Y), have been synthesized (L1 = 2,2’-bipyridine, L2 = 1,10-phenanthroline, and L3 = dipyrazine [2,3-f:2’,3′-h] quinoxaline). These results allow us to investigate the N-terminal group-containing auxiliary-ligand effect on the magnetic properties. Magnetic studies indicate that compounds 1–3 are not single-molecule magnets under zero dc field, but compound 4 is a typical zero-dc-field single-molecule magnet with an effective energy barrier of 112.12(18) K. Compound 1 is not an SMM even under an applied dc field, and compounds 2–3 show SMM behavior under an applied dc field. Moreover, compound 4 exhibits two relaxation processes under an applied dc field. Magnetic studies of the diluted analogues show that the origin of slow magnetic relaxation mainly originates from the single-ion anisotropy of the DyIII ion. These results further confirm that the ligand field has a significant effect on the magnetic properties of DyIII compounds.