High-nuclear lanthanide clusters are generally formed by the rapid accumulation of simple building units. Thus, tracking and observing the stepwise assembly process, which is vital for understanding the assembly mechanism, are extremely difficult. Herein, the decanuclear nanocluster [Dy 10 (L 1 ) 6 (μ 5 -NO 3 ) 2 (OAc) 10 (HOAc, and 3-amino-1,2-propanediol (L 3 ). The reaction process was further tracked by time-dependent high-resolution electrospray ionization mass spectrometry, and seven reaction intermediate fragments were screened. A stepwise assembly mechanism was observed based on these fragments, that is, L → Dy1 → Dy2 → Dy3 → Dy4 → Dy5 → Dy6 → Dy10. This study is the first to discover a stepwise assembly mechanism during the formation of high-nuclear lanthanide clusters (cluster nucleus > 3). Magnetic studies have shown the multiple relaxation behavior of Dy10.
Although the design and synthesis of high-nuclear lanthanide clusters with specific shapes and functions have been active, effective experience and rules to guide the further systematic expansion of lanthanide clusters...
The assembly process of lanthanide clusters often involves various complex assembly methods. Hence, studying the stepwise assembly mechanism is extremely difficult. In the assembly process of lanthanide clusters, if the in situ reaction or competitive reaction is involved, the reaction intermediates undergo rapid and complex changes, which makes research on the assembly mechanism even more difficult. Herein, 1-methyl-1H-benzo[d]imidazole-2-carbaldehyde (L a ) and 1-aminonaphthalen-2-ol (L b ) undergo a stepwise assembly reaction with Dy(III) salts under the promotion of a in situ Schiff base reaction to achieve Dy2 synthesis. The stepwise assembly mechanism is L a + L b → HL 1 → Dy1 → Dy2. In the above Dy2 formation reaction, L a is changed to 2-hydroxy-3-methoxybenzaldehyde (L c ), and then pyridin-2-ylmethanamine (L d ) is added. We have found that two different Schiff base ligands are formed in situ, and both are coordinated with Dy(III) ions to form a mixed ligand cluster Dy4 by competitive and stepwise assembly. The assembly mechanism is L b + L c /L c + L d → L 2 /L 3 → Dy1′ → Dy2′ → Dy3′ → Dy4′. We have tracked the competitive assembly process driven by the in situ Schiff base reaction in the lanthanide clusters and proposed its competitive assembly mechanism. Magnetic relaxation studies reveal single-molecule magnet behavior under zero external direct-current field with U eff = 19.6 K and τ o = 1.7 × 10 −5 s for Dy2 and U eff = 10.0 K and τ o = 2.6 × 10 −5 s for Dy4.
When reaction conditions change, products with different shapes and connections are usually obtained. Thus, the fine-tuning of structures in crystal engineering is challenging. We used the bisacylhydrazone ligand with multiple...
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