Two Dy(III) Single-Molecule Magnets with Their Performance Tuned by Schiff Base Ligands

To develop new lanthanide single-molecule magnets (SMMs), two new complexes of [Dy-2(MOH)(2)(HL1)(2)(NO3)(2)].2MeOH (1) and [Dy-6(mu(3)-OH)(2)(L-2)(2)(HL2)(2)(H2L2)(2)Cl-2(EtOH)(2)]Cl-2.3EtOH.CH3CN (2) were obtained by reacting Dy(NO)(3).6H(2)O with 3-amino1,2-propanediol in the presence of 2-hydroxynaphthaldehyde for 1 and by reacting DyCl3.6H(2)O with 1,1-di(hydroxymethy1)pethylamine in the presence of 2-hydroxynaphthaldehyde for 2, respectively, in which the Schiff base ligands of 3-(((2-hydroxynaphthaen-l-yl)methylene)amino)propane-1,2-diol (H3L1) and 2-(beta-naphthalideneamino)-2-(hydroxylmethyl)-1-propanol (H3L2) were in situ formed. The two Dy(III) ions in 1 are linked by two O-alkoxy atoms of two (HL1)(2-)ligands to build a dinuclear skeleton. Complex 2 presents a nearly planar hexanuclear skeleton constructed from four edge-shared triangular Dy-3 units with the two peripheral Dy-3 units consolidated by two mu(3)-O bridges and the two central Dy3 units consolidated by one mu(3)-O bridge. Obviously, they exhibit a different topological arrangement resulting from the linkage of the Schiff base ligands. Both of them are typical SMMs under zero dc fields, with a U-eff/k(B) value of 34 K for 1 and 40 K for 2, respectively. Multiple processes are involved in the relaxation processes of 1 and 2. The different SMM performances of the two titled complexes reveal a tuning effect of Schiff base ligands through tuning the coordination environments and topological arrangements of dysprosium(III) ions, which is supported by the theoretical calculations.