Dramatic impact of the lattice solvent on the dynamic magnetic relaxation of dinuclear dysprosium single-molecule magnets

Abstract

Two dinuclear dysprosium single-molecule magnets (SMMs) with a nearly identical core structure, namely [Dy₂(DMOP)₂(DBM)₄(CHCl₃)₄] (1) and [Dy₂(DMOP)₂(DBM)₄(C₂H₄Cl₂)₂] (2) (DMOP = 2,6-dimethoxyphenol, DBM = dibenzoylmethane), and their Y(III) (3) and Gd(III) (4) analogues were structurally and magnetically characterized. Despite the fact the phenoxyl of DMOP can only transfer weak exchange coupling and the local coordination environment around the individual Dy(III) ion is in a low geometrical symmetry, their joint contribution ultimately leads to significant zero-field slow magnetic relaxation behaviours. It is interesting to note that the effective energy barrier (U_eff) of the magnetization reversal was nearly doubly improved by only deliberately replacing or losing the lattice solvents while maintaining the Dy2 core structure. Ab initio calculations confirmed that changing the lattice solvents induced the intramolecular coupling change and impacted the dynamic magnetic relaxations. The significant enhancement of an SMM's performance depending on the lattice solvents indicated that it is possible to improve an SMM's properties by tuning the guest molecules.