In recent years, our group used HRESI-MS to track the formation of several lanthanide clusters and proposed their assembly mechanism. For example, the assembly mechanism of Dy-exclusive clusters Dy3, Dy4, Dy10, and Dy12 was proposed.[1-5] 

In our latest paper, we synthesized a double-cage dysprosium cluster Dy₆₀ by using a multidentate chelate-coordinated diacylhydrazone ligand under solvothermal conditions. Two Dy₃₀ cages were included in the Dy₆₀ structure, and the above two cages were connected via OAc^-. The core of Dy₆₀ was composed of eight triangular Dy₃ and twelve fold linear Dy₃ units. We further changed the alkali added in the reaction system and successfully obtained a single caged-shaped cluster Dy₃₀, which could be considered an intermediate in Dy₆₀ formation. Time-dependent, high-resolution electrospray ionization mass spectrometry (HRESI-MS) was used to track the formation of double-cage dysprosium cluster Dy₆₀. Seven intermediate fragments were screened and further combined with the changing trend of intermediate fragments in different time periods. The possible self-assembly mechanism was proposed as follows: H₆L¹→DyL¹→Dy₂L¹→Dy₃L¹→Dy₄L¹→Dy₅(L¹)₂→Dy₃₀(L¹)₁₂→Dy₆₀(L¹)₂₄. We tracked the formation of Dy₃₀, and the six intermediate fragments were screened. We proposed the following possible assembly mechanism: H₆L¹→DyL¹→Dy₂L¹→Dy₃L¹→Dy₄L¹→Dy₅(L¹)₂→Dy₃₀(L¹)₁₂. The assembly mechanism of Dy₃₀ further verified the formation of Dy₆₀. To our knowledge, this work is the first to use HRESI-MS for tracking the formation of cage-shaped Ln(III) clusters. This work provided a set of methods to study the formation tracking and assembly mechanism of high-nuclear lanthanide clusters. It also lays the foundation for the further design and manipulation of high-nuclear lanthanide clusters.

For the details, check out our article "Assembly of Bis-/Single Cage-shaped Dysprosium Nanoclusters (Dy₆₀/Dy₃₀)" in Communications Chemistry!

• Zhu, Z.-H. et al. A triangular Dy₃ single-molecule toroic with high inversion energy barrier: magnetic properties and multiple-step assembly mechanism. Inorg. Chem. Front. 5, 3155–3162 (2018).
• Wang, H.-L. et al. Tracking the Stepwise Formation of the Dysprosium Cluster (Dy₁₀) with Multiple Relaxation Behavior. Inorg. Chem. 58, 9169–9174 (2019).
• Ma, X.-F. et al. Formation of nanocluster {Dy₁₂} containing Dy-exclusive vertex-sharing [Dy₄(μ₃-OH)₄] cubanes via simultaneous multitemplate guided and step-by-step assembly. Dalton Trans. 48, 11338–11344 (2019).
• Wang, H.-L. et al. Step-by-Step and Competitive Assembly of Two Dy(III) Single-Molecule Magnets with Their Performance Tuned by Schiff Base Ligands. Cryst. Growth Des. 19, 5369–5375 (2019).
• Mo, K.-Q. et al. Tracking the Multistep Formation of Ln(III) Complexes with in situ Schif Base Exchange Reaction and its Highly Selective Sensing of Dichloromethane. Sci. Rep. 9, 12231–12237 (2019).