Tetranuclear [MDy]2 compounds and their dinuclear [MDy] (M = Zn/Cu) building units: their assembly, structures, and magnetic properties.

The reactions between a salen ligand N,N'-bis(3-methoxysalicylidene)-1,2-cyclohexanediamine (H2L) and different metal salts lead to the formation of four 3d-4f [MDy] and [MDy]2 (M = Zn/Cu) compounds, where the [MDy]2 can be considered as resulting from the assembly of two [MDy] building blocks. Field-induced single molecule magnet (SMM) behavior was observed in [ZnDy] and [CuDy] compounds with the effective suppression of fast quantum tunneling under a dc field. Moreover, the [ZnDy]2 compound demonstrates typical SMM behavior, which may originate from the high axial anisotropy of Dy ions correlating to the change of coordination geometry and enhanced ferromagnetic interactions between Dy ions via the coupling of two [DyZn] units. The result suggests the positive effects of coupling blocking units to enhance their SMM behavior, presenting a promising strategy for constructing efficient heterometallic SMMs.