Playing with isomerism and N substitution in pentalenedione derivatives for organic electrode batteries: how high are the stakes?†
New concepts to design innovating and top-performing redox-active organic molecules based electrodes should push forward and promote an eco-friendly alternative to classical Li-ion batteries. In this promising research area, density functional theory calculations lend support to experiments through the prediction of redox voltage and give promise to rationalize the trends, thus providing a general approach for engineering advanced materials. In this study in which we analysed spin density/net atomic charges distribution along with global energy decomposition thanks to Bader's partitioning of the molecular space, a vision for designing pentalenedione derivatives by fine tuning of the redox potential properties is presented. The concept relies on combined effects of isomerism and N single/double substitution for CH on the parent backbone. Such dual nature modification is able to provide a series of compounds within the range of 2.2–3.6 V vs. Li+/Li (against a more restricted range of 2.2–2.8 V vs. Li+/Li for the sole effect of isomerism on the unsubstituted parent compounds). The incidence of double N substitution alone generally follows an almost additive rule based on the combined actions of the composing single N substitutions. Few exceptions to the rule were, however, also observed and rationalized. Beyond learning gained for this peculiar family, these results may have exciting implications for future design strategies.