Impact of the coordination environment on the magnetic properties of single-molecule magnets based on homo- and hetero-dinuclear terbium(iii) heteroleptic tris(crownphthalocyaninate)

Abstract

A series of Tb^III triple-decker heteroleptic crownphthalocyaninate complexes consisting of a homodinuclear compound [(15C5)₄Pc]Tb[(15C5)₄Pc]Tb(Pc) (1), and two novel heterodinuclear compounds [(15C5)₄Pc]Tb[(15C5)₄Pc]Y(Pc), (2) and [(15C5)₄Pc]Y[(15C5)₄Pc]Tb(Pc) (3), have been synthesized. All compounds were characterised using UV-Vis spectroscopy, HR-ESI-MS, MALDI-TOF-MS, and ¹H NMR spectroscopy, followed by exploration into the effects of lanthanide coupling and ligand field symmetry on the magnetic properties of these complexes using SQUID magnetometry. Magnetic measurements on the homonuclear Tb^III complex (1) displayed non-negligible ferromagnetic coupling between magnetic ions, eliciting a high zero-field energetic barrier to the magnetic relaxation of U_eff = 229.9(0) K, while the heteronuclear Tb^III/Y^III complexes displayed single-ion field-induced slow relaxation of the magnetization; yielding energetic barriers of U_eff = 129.8(0) K for 2, and 169.1(8) K for 3.