Modulating the slow magnetic relaxation of a mononuclear Dy(iii) single-molecule magnet via a magnetic field and dilution effects

A beta-diketonate mononuclear dysprosium complex, with the formula [Dy(dpq)(BTFA)(3)] (1), has been prepared via self-assembly between 3-benzoyl-1,1,1-trifluoroacetone (BTFA) and dipyrido [3,2-d:2 ',3 '-f]quinoxaline (dpq) ligands. The crystallographic data reveal that the central Dy(iii) ion is eight-coordinated by six oxygen atoms from three BTFA ligands and two N atoms from auxiliary dpq ligands, forming an approximately square-antiprismatic (SAP) coordination geometry with a D-4d axial symmetry. Magnetic measurements point out that complex 1 exhibits single-molecule magnet (SMM) behaviours with an anisotropy barrier of 45.65 K under a zero direct-current (dc) field. With an applied dc field of 1200 Oe, the quantum tunnelling of the magnetization (QTM) is suppressed in 1 with an enhanced effective barrier of 178.42 K. A diamagnetic Y(iii) analogue [Y(dpq)(BTFA)(3)] (2) and diluted species [Dy0.06Y0.94(BTFA)(3)(dpq)] (1@Y) were constructed to further perform the dilution experiment. The results unveil that the SMM behaviour observed in 1 is of molecular origin and is related to the single-ion magnetic behaviour of Dy(iii) itself, even though the elimination of the dipolar and intermolecular interactions can modestly slow down the magnetic relaxation rate. The relaxation mechanisms and magneto-structure relationship are rationally discussed by ab initio calculations as well.

Automated summary

A mononuclear dysprosium complex with single-molecule magnet behavior was synthesized, and dilution experiments revealed the molecular origin of the magnetic behavior. Ab initio calculations were used to discuss the relaxation mechanisms and magneto-structure relationship.