Mixed-anion templated cage-like lanthanide clusters: Gd₂₇ and Dy₂₇

Two nanoscale clusters whose metals are exclusively lanthanides, and whose formulas are [(ClO₄)@Ln₂₇(μ₃-OH)₃₂(CO₃)₈(CH₃CH₂COO)₂₀(H₂O)₄₀]·(ClO₄)₁₂·(H₂O)₅₀ (abbreviated as Ln₂₇. 1, Gd; 2, Dy), were synthesized. Structural analysis showed that the 27 lanthanide ions were organized into a beautiful cage-like structure templated by eight CO₃²⁻ groups, which were generated from the fixation of atmospheric CO₂. Acting as a template guest, one ClO₄⁻ group was encapsulated in the Ln₂₇ cage. The Ln₂₇ compound is by far the largest odd-numbered lanthanide cluster synthesized to date. In magnetization studies of these two compounds, isotropic Gd₂₇ exhibited a large MCE of 41.8 J kg⁻¹ k⁻¹ at 2 K for ΔH = 7 T, while anisotropic Dy₂₇ displayed a slow relaxation of its magnetization.