A new breakthrough in low-coordinate Dy(iii) single-molecule magnets

Abstract

Low-coordinate lanthanide (Ln) complexes have attracted considerable attention in the field of molecular magnetism by virtue of their excellent potential in constructing high-performance single-molecule magnets (SMMs). From the chemical synthesis point of view, it is challenging to isolate stable Ln(III) complexes with a coordination number (CN) lower than six owing to the large ionic radius, variable coordination pattern and little preference in the bond direction of Ln(III) ions. Herein, a super bulky Schiff-base ligand HL (2-((2,6-dibenzhydryl-4-isopropylphenylimino)methyl)-4,6-di-tert-butylphenol) was used to construct a five-coordinate mononuclear Dy(III) complex, DyL₂I (5-Dy-I). Magnetic investigations showed that the strong interaction between Dy(III) and phenolate induces a strong block of magnetization giving the largest anisotropy barrier of 1237 cm⁻¹ and the highest blocking temperature up to 20 K for any reported mononuclear Ln(III) SMMs with CN < 6, which greatly motivated researchers to use a bulky monodentate phenolate ligand to synthesize a two-coordinate Dy(III) SMM.