Manipulation of Mixed Ligands to Form Single-Layer and Double-Layer Lanthanide Clusters and Their Magnetic Properties

Abstract

There have been many examples of synthesizing multinuclear lanthanide clusters of special shapes, such as spherical, cage-shaped, tubular, and so on. However, synthesizing multinuclear lanthanide clusters with distinct layered structures possess a challenge. We use the ligands 2,3-dihydroxybenzaldehyde, benzohydrazide and pyridin-2-ylmethanamine to obtain a single layer of six-core lanthanide clusters [Dy6(μ3-O)(μ3-OH)4(L2)3(L3)3(L4)3(H2O)3]Cl6·CH3OH (1) and [Gd6(μ3-O)(μ3-OH)4(L2)3(L3)3(L4)3(H2O)2(CH3OH)]Cl6·CH3OH·3CH3CN (2). The central metal ion of cluster 1 presents a triangular lattice shape. We changed the ligands to 2-hydroxy-3-methoxybenzaldehyde and 2-aminobenzoic acid and obtained the double-layer eight-core lanthanide clusters [Dy8(μ3-OH)6(L5)2(L6)8] (3) and [Gd8(μ3-OH)6(L5)2(L6)8]·4CH3OH·CH3CN (4). The upper and lower layers of cluster 3 have four metal ions, respectively, forming a huge cavity inside the structure. This is the first time that a multinuclear lanthanide cluster with a layered structure has been constructed by the in situ reaction of mixed ligands. AC susceptibility test shows that the imaginary part signals of cluster 1 do not show frequency dependence and the imaginary part signals of cluster 3 show frequency dependence at low temperatures. By fitting the Arrhenius equation, we obtain Ueff = 2.87 K and τ0 = 2.76 × 10–4 s.