Shape-Complementary Multicomponent Assembly of Low-Symmetry Co(III)Salphen-Based Coordination Cages

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Metal-mediated self-assembly is widely used for constructing nanosized objects.
• Existing systems often feature highly symmetric structures using a single ligand type.
• Integrating multiple ligands presents challenges like narcissistic separation and statistical mixtures.

Purpose of the Study:

• To demonstrate a rational and high-yielding synthesis of structurally complex coordination cages.
• To create heteroleptic coordination cages with up to four differentiable bridges using cobalt(III)salphen metal nodes.
• To explore the advantages of kinetically inert cobalt(III)salphen for stable molecular machinery and catalysis.

Main Methods:

• Utilized a combination of metal-templated macrocyclization, bridging ligands, and shape-complementarity.
• Employed a one-pot reaction approach for synthesizing three new heteroleptic coordination cages.
• Characterized the resulting cages using single crystal X-ray analyses.

Main Results:

• Successfully synthesized structurally complex, lantern-shaped cages with up to four differentiable bridges.
• Created cages with varying ligand arrangements around symmetric and asymmetric Co2-bis-salphen rings.
• Demonstrated the ability to distinguish all four connections between metal centers in the most complex structure.

Conclusions:

• The developed method enables the rational and high-yielding synthesis of complex heteroleptic coordination cages.
• Cobalt(III)salphen-based cages offer enhanced structural and chemical stability compared to dynamic systems.
• These stable cages are advantageous for applications in enzyme-like catalysis and molecular machinery.