The development of bioinspired copper complexes for CO₂ activation and hydration

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Carbon dioxide (CO2) activation is crucial for developing sustainable chemical processes.
• Copper complexes are promising catalysts for CO2 conversion.
• Understanding the mechanisms of CO2 activation by metal complexes is essential for catalyst design.

Purpose of the Study:

• To synthesize and characterize thioether-modified pyridine-2,6-dicarboxamide copper complexes.
• To investigate the mechanisms of CO2 activation by monomeric and dimeric copper complexes.
• To explore the role of soft sulfur donors in copper-catalyzed CO2 reactivity.

Main Methods:

• Synthesis and characterization of copper complexes ([Cu(L)], 1, and its dimer, 2).
• Spectroscopic and electrochemical studies to probe CO2 activation mechanisms.
• Investigation of reactivity under varying conditions (resting state, reduction, electrochemical).

Main Results:

• The thioether moiety stabilizes the Cu(I) state and improves redox reversibility.
• The µ-OH dimer (2) directly reacts with CO2 to form a bicarbonate species.
• The monomer (1), upon reduction, forms a CO2-bound intermediate via a redox-triggered pathway.
• Both complexes show irreversible Cu(II/I) reduction with CO2, proceeding via an EC-type mechanism.

Conclusions:

• Soft sulfur donors in copper complexes facilitate CO2 reactivity.
• Different copper complex structures (monomer vs. dimer) exhibit distinct CO2 activation mechanisms.
• These findings provide a foundation for designing advanced copper-based catalysts for CO2 conversion.