Macrocyclic Hexagonal Bipyramidal Dy(III)-Based Single-Molecule Magnets with a D_6h Symmetry

The design and synthesis of air-stable single-molecule magnets (SMMs) with large effective barriers of magnetic reversal and remarkably slow relaxation times are challenging. The design and synthesis of air-stable complexes with large effective magnetic reversal barriers and remarkably slow relaxation times are challenging in the field of SMMs. Herein, we present an air-stable hexagonal bipyramid [DyIII(bpyN4)(Ph3SiO)2](BPh4) (1) (bpyN4 = neutral hexaaza macrocyclic Schiff base ligand derived of 6,6′-diformyl-2,2′-bipyridyl and triethylenetetramine). The magnetic data demonstrate that the complex shows zero-field SMM behavior with magnetic hysteresis loops up to 13 K and an effective barrier of 584 K for 1. The experimental effective barrier is close to the energy of the first excited Kramers doublet (EKD1) obtained from ab initio calculations.