Simultaneous assembly of mononuclear and dinuclear dysprosium(III) complexes behaving as single-molecule magnets in a one-pot hydrothermal synthesis

Abstract

Two dysprosium(III) complexes derived from 2,2′-bipyridine-6,6′-dicarboxylic acid (H2bpdc), [Dy(bpdc)(Hbpdc)]·3H2O (1) and [Dy2(bpdc)3(H2O)3]·2.125H2O (2), were isolated from the same hydrothermal reaction container as different phases. Compound 1 is a mononuclear complex with a DyN4O4 coordination polyhedron; whereas compound 2 is a dinuclear complex with two types of eight coordinated dysprosium(III) ions, showing DyN4O4 and DyN2O6 coordination polyhedra, respectively. Remarkably, a new type of (H2O)6 supramolecular aggregate exists in the crystal structure of 2. Magnetic investigations revealed that 1 is a field-induced single-ion magnet with an effective energy barrier of 45.6 K, exhibiting two-step magnetic relaxation; while an intramolecular ferromagnetic interaction exists in 2, which is a field-induced single-molecule magnet, displaying two-step magnetic relaxation too, with effective energy barriers of 53.4 and 92.1 K, respectively.