Redox-Switchable Halogen Bonding in Haloanthracene Mediators Enables Efficient Electrocatalytic C-N Coupling

Area of Science:

• Organic Chemistry
• Catalysis
• Electrochemistry

Background:

• Redox mediators are crucial for electrocatalysis.
• Controlling substrate preorganization and reactivity is key for efficient C-N bond formation.

Purpose of the Study:

• To develop novel redox mediators utilizing redox-switchable halogen bonding.
• To enhance intramolecular C-N bond formation via electrocatalysis.
• To optimize mediator structure for improved catalytic performance.

Main Methods:

• Synthesis and evaluation of 9-halo-10-arylanthracene redox mediators.
• Systematic screening of halogenated mediators with 2-aminobiphenyl substrates.
• Kinetic analysis using foot-of-the-wave analysis.
• Bulk electrolysis experiments.
• Computational studies (DFT) to elucidate the mechanism.

Main Results:

• The iodoanthracene derivative 1a showed superior performance.
• Mediator 1h, featuring a 3,5-bis(trifluoromethyl)phenyl group, exhibited over an order of magnitude higher activity.
• High yields and short reaction times were achieved.
• Computational studies confirmed strengthened halogen bonding in the radical cation state, facilitating proton-coupled electron transfer (PCET).

Conclusions:

• A new design paradigm for redox mediators based on redox-induced noncovalent interactions was established.
• Halogen-bonding-assisted PCET is a powerful strategy for molecular electrocatalysis.
• The developed mediators offer enhanced control over reactivity and selectivity.