Giant Crown-Shaped Dy₃₄ Nanocluster with High Acid–Base Stability Assembled by an out-to-in Growth Mechanism

Lanthanoid metal ions have large ionic radii, complex coordination modes, and easy distortion of coordination spheres, but the design and synthesis of high-nucleation lanthanoid clusters with high stability in solution (especially aqueous solution) are challenging. Herein, a diacylhydrazone ligand (H₂L¹) with multidentate chelating coordination sites was used to react with Dy­(OAc)₃·4H₂O under solvothermal conditions to obtain an example of a 34-nucleus crown-shaped dysprosium cluster [Dy₃₄(L)₈(μ₂-OH)­(μ₃-OH)₂₁(μ₃-O)₁₄(OAc)₃₁(OCH₃)₂(H₂O)₁₅]­(OAc)₃ (1). Structural analysis showed that the bisacylhydrazone ligand H₂L¹ with polydentate chelate coordination sites could rapidly capture Dy^III ions, thereby forming 34-nucleus crown-shaped dysprosium cluster 1 following the out-to-in growth mechanism. Cluster 1 remained stable after immersion in solutions with different pH values (3–14) for 24 h. To the best of the authors’ knowledge, high-nucleation lanthanoid clusters with excellent strong acid and base stability and water stability are very rare. Meanwhile, high-resolution electrospray mass spectrometry molecular ion peaks produced by cluster 1 were captured, which proved to be stable also in organic solvents. Magnetic research showed that cluster 1 exhibited frequency-dependent behavior. This work provides a new idea for designing and synthesizing high-nucleation lanthanoid clusters with high stability.