Magnetic Relaxation Dynamics of a Binuclear Diluted Er(III)/Y(III) Compound Influenced by Lattice Solvent

It is crucial to investigate the slow relaxation mechanisms of binuclear Er^III -based single-molecule magnets (SMMs) and explore strategies for optimizing their magnetic properties. Herein, a doped compound, [Y_1.75 Er_0.25 (thd)₄ Pc] ⋅ 2C₆ H₆ (YEr ⋅ 2C₆ H₆ , Hthd=2,2,6,6-tetramethylheptanedione, H₂ Pc=phthalocyanine), was synthesized by doping the paramagnetic erbium(III) compound Er₂  ⋅ 2C₆ H₆ in the diamagnetic yttrium(III) matrix Y₂  ⋅ 2C₆ H₆ . The doping effect was studied using SQUID magnetization measurements. The results suggest that magnetic-site dilution improves the magnetic property from a fast relaxation of the pure Er^III compound to a typical SMM relaxation process of the doped sample. In this binuclear system, the dominant single-ion relaxation is entangled with the neighboring Er^III ion through the intramolecular Er^III ⋅⋅⋅Er^III interaction, which plays an important role in suppressing the quantum tunneling of the magnetization (QTM) process. Furthermore, the influence of lattice solvents on single-ion relaxation was studied. By releasing the benzene molecules, compound YEr ⋅ 2C₆ H₆ can be successfully transformed to a desolvated sample YEr accompanied by structural alteration and improved SMM performance.