Programming Reaction-Network Bifurcations for Selective Amino Acid Electrosynthesis

Area of Science:

• Electrochemistry
• Organic Synthesis
• Catalysis

Background:

• Electrosynthesis of amino acids from inorganic nitrogen is a promising route for biologically relevant C-N molecules.
• Selective C-N coupling is hindered by competing ammonia formation and an uncontrollable hydroxylamine intermediate.

Purpose of the Study:

• To develop a strategy to control the reaction-network bifurcation of hydroxylamine for selective amino acid electrosynthesis.
• To overcome kinetic limitations in C-N coupling pathways.

Main Methods:

• Development of a programmable reaction-network bifurcation (PRNB) strategy using atomically precise dual-site metallenes.
• Investigation of hydroxylamine (*NH2OH) reaction pathways at a dual-site catalyst.
• In situ spectroscopy and kinetic isotope measurements to elucidate reaction mechanisms.

Main Results:

• The PRNB strategy successfully directed hydroxylamine bifurcation towards C-N coupling over ammonia formation, achieving a 28.5-fold improvement.
• High Faradaic efficiency (83.2%) and formation rate (>885 mmol/gcat/h) for glycine synthesis were achieved, sustained over 225 hours.
• Demonstrated efficient synthesis of diverse amino acids including alanine, glutamate, and leucine.

Conclusions:

• The dual-site metallene catalyst reprograms hydroxylamine's bonding preference, favoring C-N coupling for oxime formation.
• The catalyst reorganizes interfacial water networks, significantly lowering hydrogen-transfer barriers for efficient glycine production.
• PRNB offers a general paradigm for controlling complex reaction-network bifurcations in chemical synthesis.