Gradient Construction of High-Efficiency Lanthanide Polynuclear Nanocages for Three-Component Ugi Reactions

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Catalysis

Background:

• Polynuclear coordination nanocages are underexplored catalysts for multicomponent Ugi reactions.
• These nanocages offer advantages like spacious cavities and tunable metal active sites.

Purpose of the Study:

• To design and synthesize novel lanthanide-based metal-organic coordination nanocages (MOCN).
• To investigate their efficacy as catalysts for the three-component Ugi reaction.
• To explore the impact of heterometallic composition on catalytic performance.

Main Methods:

• Synthesis of a bridging ligand (H5L) with imidazole and acylhydrazone units.
• Construction of three lanthanide-based MOCN (Tb6, Zn6Tbb6, and Na2Zn4Tbb6) via metal salt and pH modulation.
• Evaluation of catalytic activity in the three-component Ugi reaction.

Main Results:

• Successfully constructed Tb6, Zn6Tbb6, and Na2Zn4Tbb6 nanocages with internal cavities (9.0-10.0 Å).
• Nanocages exhibited densely distributed Lewis acid sites, facilitating Ugi reaction catalysis.
• Gradient-constructed heterometallic nanocages (Zn6Tbb6 and Na2Zn4Tbb6) showed superior activity and adaptability.
• Na2Zn4Tbb6 retained >80% yield after five runs, indicating excellent stability.

Conclusions:

• Demonstrated the feasibility of gradient assembly for lanthanide-based MOCN catalysts through metal salt engineering.
• Highlighted the excellent reactivity and stability of heterometallic MOCN for Ugi reactions.
• Provided a promising strategy for developing high-performance nanocage catalysts in supramolecular catalysis.