Dinuclear Lanthanide-Carboxylate Compounds: Field-Induced Slow Relaxation of Magnetization for Dysprosium(III) Analogue

摘要

Three chiral dinuclear lanthanide compounds, Ln(2)(mu(2)-L)(4)(L)(2)(phen)(2) (Ln=Dy (1), Gd (2), and Er (3); phen=1,10-phenanthroline), have been synthesized using the (S)-(+)-2-(6-methoxy-2-naphthyl)propionic acid (HL) ligand. The two lanthanide centres in compound Ln(2)(mu(2)-L)(4)(L)(2)(phen)(2) are bridged by four carboxylate groups to give a dinuclear Ln(2)(mu(2)-L)(4) core. The square antiprismatic coordination environment for each lanthanide centre is further completed by a chelating carboxylate group from another L- ligand and two nitrogen atoms from the phen ligand. A weak antiferromagnetic interaction between the two Gd-III ions is observed in compound 2. The Dy analogue displays field-induced slow magnetic relaxation behaviour with an effective energy barrier U-eff/k of 17.24(2) K and a pre-exponential factor (0) of 2.7(1)x10(-6)s. However, no slow relaxation phenomenon was observed for the Er derivative even in the presence of 2kOe applied field.