Voltammetric Studies on the Electrochemical Interaction between Bipyridines and CO₂

A comparative study was conducted on the electrochemical interaction between CO2 and various bipyridines, including 2,2 '-, 3,3'-, and 4,4'-bipyridine (4,4'-BPy), as well as perfluoro-4,4'-bipyridine (PF-4,4'-BPy).Among these, 4,4'-BPy exhibited the most robust performance, particularly when paired with weakly coordinating quaternary ammonium cations, such as tetrabutylammonium (Bu4N + ).The use of these bulky cations proved highly effective in facilitating the electrochemical interaction with CO2, likely due to their attenuated electrostatic interaction with the bipyridine anionic species, which facilitates reversible CO2 binding.In contrast, PF-4,4'-BPy exhibited no electrochemical interaction with CO2; its radical anion showed insufficient nucleophilicity to overcome the activation barrier for CO2 binding, while the corresponding dianion was highly unstable, leading to rapid decomposition potentially initiated by a reductive defluorination process.