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.