Chemically Driven Contraction and Elongation: Interconversion between Molecular Figure of Eight

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Organic Synthesis

Background:

• Macrocyclic compounds offer unique structural and binding properties.
• Developing molecules with selective metal binding sites is crucial for advanced applications.
• Orthogonal templating centers within a single macrocycle present synthetic challenges and opportunities.

Purpose of the Study:

• To synthesize a 90-membered macrocycle incorporating diphenyl-phenanthroline (dpp) and pyridine-diamide (pda) moieties.
• To investigate the selective metal binding and complex formation behavior of the synthesized macrocycle.
• To demonstrate the bimodal operation and metal-exchange capabilities of the macrocyclic system.

Main Methods:

• Amide bond formation over 10 synthetic steps to construct the macrocycle.
• Sequential treatment with transition metal ions, Cu(I) and Co(III), to form complexes.
• Selective demetalation and re-metalation to achieve interconversion between different complexation states.

Main Results:

• Successful synthesis of a 90-membered macrocycle with alternating dpp and pda units.
• Demonstrated selective complexation of Cu(I) with dpp units and Co(III) with pda units, forming figure-of-eight structures.
• Achieved interconversion between Cu(I) and Co(III) complexes via metal-exchange, showcasing bimodal behavior.

Conclusions:

• The synthesized macrocycle exhibits orthogonal binding sites, enabling selective and bimodal metal complexation.
• The ability to interconvert between different metal complexes highlights the dynamic and responsive nature of the macrocyclic system.
• This work provides a foundation for designing sophisticated macrocyclic architectures with tunable coordination properties.