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(MeOH)(HL)(NO)]·2MeOH (1) and [Dy(μ-OH)(L)(HL)(HL)Cl(EtOH)]Cl·3EtOH·CHCN (2) were obtained by reacting Dy(NO)·6HO with 3-amino-1,2-propanediol in the presence of 2-hydroxynaphthaldehyde for 1 and by reacting DyCl·6HO with 1,1-di(hydroxymethyl)ethylamine in the presence of 2-hydroxynaphthaldehyde for 2, respectively, in which the Schiff base ligands of 3-(((2-hydroxynaphthaen-1-yl)methylene)amino)-propane-1,2-diol (HL) and 2-(β-naphthalideneamino)-2-(hydroxylmethyl)-1-propanol (HL) were in situ formed. The two Dy(III) ions in 1 are linked by two O atoms of two (HL) ligands to build a dinuclear skeleton. Complex 2 presents a nearly planar hexanuclear skeleton constructed from four edge-shared triangular Dy units with the two peripheral Dy units consolidated by two μ-O bridges and the two central Dy units consolidated by one μ-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/ k 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.