Engineering dysprosium(iii) single-ion magnets via modular synthesis with strongly axial ligands

Abstract

The solvothermal reaction of a mononuclear dysprosium(III) complex as building blocks with strongly axial ligands produced two solvent-free mononuclear dysprosium(III) complexes, namely [Dy(DClQ)₃(Ph₃PO)DMF] (1) and [Dy(DClQ)₃(Ph₃SiOH)DMF] (2) (DClQ = 5,7-dichloro-8-hydroxyquinolin; Ph₃PO = triphenylphosphine oxide; Ph₃SiOH = triphenylsilanol). The Dy³⁺ ions in 1 and 2 are located in distorted triangular dodecahedron (D_2d) coordination environments. Interestingly, slow relaxation of magnetization at zero field was evidenced with the U_eff of 121(2) K for complex 1, while field-induced slow relaxation of magnetization was observed for 2. Relaxation dynamics analyses disclose that the combined Orbach, Raman, and QTM mechanisms are dominant in 1, whereas Orbach and Raman mechanisms play an important role in 2 under an applied field. The magnetic performance of single-ion magnet (SIM) properties of 1 and 2 is better than that of the parent mononuclear Dy(III) complex, revealing a significant enhancement of magnetic behaviors by using the strongly axial ligands. The present work provides an efficient strategy to design and construct new lanthanide SIMs through a SIM modular synthetic route.