Abstract

This study investigates the electrochemical properties of a family of substituted quinoxaline-5,8-diones, in particular 2,3-diphenylquinoxaline-5,8-dione (phenylQX), 2,3-bis(4-methoxyphenyl)quinoxaline-5,8-dione (methoxyQX), and dimethyl 4,4′-(5,8-dioxo-5,8-dihydroquinoxaline-2,3-diyl)dibenzoate (benzoateQX) and their evaluation as redox carriers in CO2 capture processes, as they are capable of forming reversible adducts with CO2. The capacities of phenylQX, methoxyQX, and benzoateQX were determined by adduct formation constant, finding a log K of 11.4 for phenylQX; 9.3 for methoxyQX and 3.4 for benzoateQX. These results were contrasted with theoretical DFT calculations, which showed that these quinoxalines bind strongly to two CO2 molecules. © 2025