Bio-Inspired Electroactive Organic Molecules for Aqueous Redox Flow Batteries. 1. Thiophenoquinones

Redox flow batteries (RFB) utilizing water-soluble organic redox couples are a new strategy for low-cost, eco-friendly, and durable stationary electrical energy storage. Previous studies have focused on benzoquinones, napthoquinones, and anthraquinones as the electroactive species. Here, we explore a new class of molecules—thiophenoquinones—specifically focusing on the caldariellaquinone-, sulfolobusquinone-, and benzodithiophenoquinone-like frameworks that are used for metabolic processes in thermophilic aerobic Sulfolobus archaebacteria. We demonstrated that B3LYP/6-311+G(d,p) thermochemical calculations (using the SMD solvation model) reproduce experimental reduction potentials to within ±0.04 V. We then studied the effect of amine, hydroxyl, methyl, fluoro, phosphonic acid, sulfonic acid, carboxylic acid, and nitro functional group modifications on the reduction potential and Gibbs energy of solvation in water (using density functional theory) and aqueous solubility (using cheminformatics). Next we en...