Field-Induced Slow Magnetic Relaxation in a New Family of Tetranuclear Double-Stranded Cu₂^II–Ln₂^III Metallohelicates

High Resolution Image Download MS PowerPoint Slide A series of tetranuclear Cu 2 II Ln 2 III (Ln III from La III to Yb III ), double-stranded metallohelicates have been synthesized using a bis-bidentate flexible ligand obtained by condensing o -vanillin with 4,4′-oxydianiline. The complexes exhibit a variety of Ln III environments and decreasing coordination number along the series and several nitrato coordination modes proved by the structural determination of the La III ( 1La ), Sm III ( 4Sm ), Gd III ( 5Gd ), Er III ( 9Er ), and Yb III ( 10Yb ) derivatives. The other members of the family ( 2Ce, 3Pr, 6Tb, 7Dy, and 8Ho ) have been characterized by powder X-ray diffraction to verify their isostructurality. Susceptibility measurements show field-induced slow relaxation of the magnetization for the anisotropic Tb III and Dy III complexes and for the isotropic Gd III system.