Coordination enhancement of single-molecule magnet behavior of Tb(III)–Cu(II) dinuclear systems

Tb(III)–Cu(II) based single-molecule magnets (SMMs) were synthesized to investigate the relationship between magnetic anisotropy and the symmetry of the ligand field, by the reaction of [TbCu(o-vanilate)2(NO3)3] with 2,2-dimethyl-1,3-propanediamine (3), followed by the reaction of one another equivalent of o-vaniline (4). Both complexes behave as SMM in the temperature range of 2.8–4.0 K (3) and 2.8–5.2 K (4), showing semi-circle shapes of Cole–Cole plots with α parameters in the ranges of 0.27–0.41 and 0.11–0.32. The energy barriers Δ/kB for the spin flippings were estimated from the Arrhenius plots to be 29(2) K for 3 and 32.2(6) K for 4, respectively.

Graphical abstractSingle-molecule magnet (SMM) behaviors of two Tb(III)-Cu(II) complexes, [TbCu(L3)(No3)3(H2O) and [TbCu(L3)(NO3)(o-vanilate)(MeOH)]NO3 (L32− denotes a Schiff-base ligand formed with o-vanilate and 2,2-dimethyl-1,3-propanediamine), were investigated to reveal the relationship between coordination geometry around Tb(III) ion and the magnetic anisotropy.Figure optionsDownload full-size imageDownload as PowerPoint slide