Crystallization and Single Molecule Magnetic Behavior of Quadruple-stranded Helicate: Tuning the Anisotropic Axes

It has proven successful that bis-β-diketone ligand in proper length and flexibility is essential for the construction of multiple-stranded helicates, where two Dy3+ centers in the subtle environment would supple an opportunity to tune the anisotropic axes. Based on our previous work, we have designed a flexible bis-β-diketone ligand BTT (BTT = 3,3''-bis(4,4,4-trifluoro-1,3-dioxobutyl)-m-terphenyl), which is successfully utilized to construt a quadruple-stranded helicate in the formula of [C6H16N]2[Ln2(BTT)4] [Ln = Ce (1), Dy (2)]. Structural analysis indicates that they crystallize in the tetragonal space group P4/n, and each Ln3+ center is chelated by four diketonate moieties from four ligands, giving rise to the formation of dinuclear quadruple-stranded helicate. Magnetic measurement shows that 2 displays single molecular magnet behavior under an applied dc field of 2000 Oe. Further investigation indicates that the anisotropic axes of the Dy3+ centers could be tuned, depending on the bis-β-diketonate ligands used to assemble the Dy helicates.