Researchers from the Institute of Chemistry of the Chinese Academy of Sciences (ICCAS) have developed an electrocatalytic method for synthesizing foscarnet from carbon dioxide (CO₂) and phosphite (HPO₃²⁻) at room temperature. The researchers used an ionic-liquid-radical-mediated C–P coupling pathway and achieved a maximum Faradaic efficiency of 37.5% for foscarnet at a current density of up to 224.2 mA cm⁻².

Their work was published in Nature Catalysis.

Foscarnet is an important antiviral drug with significant clinical value. However, its conventional synthetic routes generally involve multiple steps, high costs, and hazardous reagents, making the development of a simple and efficient synthesis highly desirable. Electrosynthesis using CO₂ and Na₂HPO₃ as feedstocks offers a promising approach to overcoming the limitations of traditional routes. Nevertheless, both CO₂ and HPO₃²⁻ are chemically stable, and the reaction requires coordinated anodic and cathodic processes, making their direct coupling to form a C–P bond particularly challenging.

The researchers, led by HAN Buxing and KANG Xinchen addressed this challenge by developing an ionic-liquid-radical-mediated pathway. During electrolysis, Bpy+ cations on the surface of the IL@Bi catalyst are reduced to Bpy• radicals. These radicals subsequently transfer electrons spontaneously to CO₂, generating CO₂•− radicals and thereby markedly increasing the concentration of CO₂•− in solution.

The CO₂•− radicals then undergo C–P coupling with PO₃•²⁻ radicals generated at the anode, enabling efficient electrosynthesis of foscarnet. By coordinating the radical processes at the two electrodes, the system enables the electrochemical coupling of CO₂ and HPO₃²⁻ under room-temperature conditions.

This strategy not only provides a new approach for the co-conversion of CO₂ and HPO₃²⁻ under mild conditions, but also offers new insights into the design of other efficient electrocatalytic reaction systems.

Electrocatalytic coupling of CO₂ and HPO₃²⁻ (Image by WANG Hengan)