Two novel Dy8 and Dy11 clusters with cubane [Dy4(μ3-OH)4]8+ units exhibiting slow magnetic relaxation behaviour

Abstract

Two unique octa- and hendeca-nuclear dysprosium(III) clusters incorporating [Dy₄(μ₃-OH)₄]⁸⁺ cubane units have been synthesized with the 1,10-phenanthroline-2,9-dicarbaldehyde dioxime (H₂phendox) ligand and DyCl₃·6H₂O or Dy(OAc)₃·4H₂O. They are [Dy₈(OH)₈(phendox)₆(H₂O)₈]Cl₂(OH)₂·18H₂O·18MeOH (1) and [Dy₁₁(OH)₁₁(phendox)₆(phenda)₃(OAc)₃](OH)·40H₂O·7MeOH (2). Adjacent Dy₈ in 1 or Dy₁₁ in 2 motifs are packed by off-set π–π interactions of the aromatic rings on phendox²⁻ to generate a 3D supramolecular architecture in the honeycomb topology and with 1D or 3D channels along the c-axis. Adsorption research shows that complex 1 has selective adsorption ability for H₂O over small gas molecules (H₂, N₂, CO₂). Complex 2 is stable upon the removal of guest molecules and the desolvated compound absorbed a considerable amount of CO₂. Furthermore, the oximes underwent hydrolysis to carboxylic acid and the resulting 1,10-phenanthroline-2,9-dicarboxylate link the dysprosium atoms to form a hendecanuclear cluster of 2. Magnetic studies reveal that both clusters exhibit slow magnetic relaxation behavior, expanding upon the recent reports of the pure 4f type single-molecule magnets (SMMs).