Field-Induced Single-Ion Magnets Based on Enantiopure Chiral β-Diketonate Ligands

Abstract

A pair of homochiral β-diketonate ligands (+)-3-trifluoroacetyl)camphor (d-Htfc) and (-)-3-trifluoroacetyl)camphor (l-Htfc) were used to construct two enantiomeric pairs of Dy(III) single-ion magnets [Dy(d-tfc)3(bpy)]2 (d-1)/[Dy(l-tfc)3(bpy)]2 (l-1) (bpy = 2,2'-bipyridine) and [Dy(d-tfc)3(phen)]·2H2O (d-2)/[Dy(l-tfc)3(phen)] (l-2) (phen = 1,10-phenanthroline). The capping aromatic N,N'-donors have a dramatic influence on the structural and magnetic characteristics of the Dy(III) β-diketonate enantiomeric pairs: the cocrystal of two homochiral Dy(III) β-diketonate stereoisomers with the 2,2'-bipyridine ligand was formed, showing field-induced single-ion magnet behaviors with a two-step relaxation process, while no stereoisomerization happened for the homochiral Dy(III) β-diketonate with the 1,10-phenanthroline coligand, exhibiting a single relaxation process of the magnetization only. The anisotropy barriers of d-1 (36.5 and 46.1 K) are slightly smaller than those of l-1 (37.0 and 49.3 K), while d-2 has a larger energy barrier (30.5 K) with respect to l-2 (25.1 K).