Solvent-induced Dy2 and Dy6 clusters with disparate slow magnetic relaxation behaviors

Abstract

Two novel dysprosium-based clusters [Dy(L)(NO3)(CH3OH)]2·CH3OH (1) and [Dy3(L)2(NO3)3(OH)2]2·2CH3CN·N(CH2CH3)3 (2) are self-assembly constructed based on the same multidentate chelate-coordinated ligand H2L (H2L = N′-(2-formyl-8-hydroxyquinoline)-pyridine-2-carbohydrazide) via replacing only one kind of solvent in the synthesis processes. Single crystal X-ray diffraction measurement results indicate that two central DyIII ions, with identical nine-coordinated pattern, bridging two O atoms to form a pocket-shaped Dy2O2 core in cluster 1. However, in cluster 2, the six central dysprosium ions are connected to form a ship-like framework, which is highly similar to the boat configuration of cyclohexane. In addition, systematic magnetic studies reveal that clusters 1 and 2 display disparate magnetic relaxation behaviors. Thereinto, only cluster 1 exhibits classical feature of single-molecule magnet (SMM) behavior in temperature-dependent alternating current (ac) susceptibility measurements under a zero direct current (dc) field, while cluster 2 exhibits slow magnetic relaxation behavior at 5 kOe dc field. Accordingly, a slight change in reaction solvents has an obvious effect on the crystal structures and magnetism of cluster 1 and 2 in the reaction system.