Assembling two Dy2 single-molecule magnets with different energy barriers via fine-tuning the geometries of DyIII sites†
Abstract
The utilization of two Schiff-base ligands H2L1 and H2L2 (H2L1 = 4-chloro-2-(((3-ethoxy-2-hydroxybenzyl)imino)methyl) phenol, H2L2 = 2-(((3-ethoxy-2-hydroxybenzyl)imino)methyl)-4-methoxy-phenol) with different substituents at the backbone of phenol in the construction of dinuclear dysprosium single-molecule magnets (SMMs) is reported. Two complexes of formulae [Dy2(L1)2(NO3)2(EtOH)(DMF)]·2EtOH (1) and [Dy2(L2)2(NO3)2(MeOH)2] (2) have been prepared and structurally characterized. X-ray crystallographic analysis revealed that the four DyIII ions of 1 and 2 all adopt NO7 coordination environments. The two DyIII centers of 1 exhibit triangular dodecahedron (D2d) and square antiprism (D4d) geometries, respectively, while the two DyIII sites in 2 both show triangular dodecahedron geometry with D2d symmetry. Magnetic analyses indicated that both complexes display SMM behavior with energy barriers of 86.91 K (1) and 93.70 K (2), respectively. The slight enhancement of the energy barrier of 2 reveals that the coordination geometries of DyIII ions would affect the magnetic behaviors of 1 and 2. Complete Active Space Self-Consistent Field (CASSCF) calculations were conducted for 1 and 2 to illustrate the slight variation of the magnetic behaviors. The calculated results are well consistent with those of the experimental outcomes.