A tool for deciphering the redox potential ranking of organic compounds: a case study of biomass-extracted quinones for sustainable energy

Carbonyl compounds have emerged as promising organic electrodes for sustainable energy storage. Accelerating the process of performant materials discovery relies on the possibility of developing methodologies to enable scanning of various sets of candidates. The genesis of this educated guess strategy must be privileged to reduce the search space of experiments, accelerate this research area and contribute to sustainable effort. To address this challenge, we built a quantitative structure-activity relationship to unveil the origin of the redox potential magnitude as a function of both structural features and complexation effects. The potential of this prediction model was demonstrated on various ortho-quinones directly derived from naturally occurring catechols. In addition to the modulation provided by substituent changes, the possibility of applying various types of alkaline(-earth)-ion electrochemistry was examined thoroughly. The power of partitioning the total molecular energy into additive atomic group contributions is highlighted, and the construction of this robust strategy provides guidance towards rational selection of the most suitable compound/metal-ion couples. An upshift/downshift of the redox potential by switching from Li to Mg/Na is revealed, while the identification of the relative role played by the various components of the systems as well as electrostatic interactions is clearly identified. These results, particularly the evidence of the different substituent effects on the single/double reduction potentials and as a function of the type of electrochemistry (Li/Na/Mg), have important implications for designing new electroactive compounds with tailored redox properties.