Synthesis, structures and magnetic properties of four dysprosium-based complexes with a multidentate ligand with steric constraint

Abstract

Chemical modulation of metal complex structures holds great potential for the preparation of novel functional materials, and functional organic ligands are well-known to play a key role in the construction of metal complexes with specific properties. Herein, we design a multidentate ligand with steric constraint and different types of donors, 6,6′-(((1-(2-hydroxy-3-methoxyphenyl)-2-(pyridin-2-yl)ethane-1,2-diyl)bis(λ₂-azanediyl))bis(methylene))bis(2-methoxyphenol) (H₃L), to synthesize dysprosium-based complexes and study their magnetic properties. Depending on the experimental conditions, four new Dy-based complexes are obtained, namely, [Dy₂(H^pyL)(L)(CH₃COO)]·2CH₃CN·CH₃OH (Dy₂), [Dy₄(HL)₂(μ₃-OH)₂Cl₆]·4CH₃OH (Dy₄), [Dy₅(L)(μ₄-O)(μ₃-OH)(μ₃-OCH₃)₂(CH₃COO)₇] (Dy₅) and [Dy₆(L)₂(μ₃-OH)₄ (CH₃COO)₈]·4CH₃OH (Dy₆). Their structures are determined by single crystal X-ray diffraction. Magnetic characterization shows that the complexes Dy₂ and Dy₅ both exhibit slow magnetic relaxation behavior under zero dc field, with the effective energy barrier of magnetization reversal and a relaxation time being U_eff = 5.68 K and τ₀ = 2.3 × 10⁻⁶ s, respectively, for Dy₂, and U_eff = 3.1 K and τ₀ = 3.6 × 10⁻⁵ s for Dy₅.