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Structural Tailoring of Viologens: Tuning the Electrochemical Behaviour of a Powerful Organic Anolyte

Authors: Burešová Zuzana | Bureš Filip | Klikar Milan

Year: 2025

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Structural Tailoring of Viologens: Tuning the Electrochemical Behaviour of a Powerful Organic Anolyte	Organic molecules capable of undergoing electrochemically reversible redox transformations are of significant interest for their potential in sustainable energy storage applications. Among them, viologens - comprising 4,4′-bipyridinium salts - stand out due to their well-defined redox behaviour and favourable aqueous solubility. These paraquat-based systems undergo a two-step reversible reduction, yielding a characteristic violet radical cation and ultimately a fully reduced quinoid form. Their performance in aqueous redox flow batteries has positioned them as key organic anolyte materials. However, limitations such as poor solubility of the reduced species and relatively modest negative redox potentials hinder their broader application. To address these drawbacks, we have undertaken a systematic structural modification of the bipyridinium scaffold. A diverse library of viologen derivatives was synthesized, incorporating variations in the number and placement of nitrogen atoms, π-system extension and its planarity, and N-alkyl substitution patterns. The electrochemical behaviour of these compounds was thoroughly evaluated under both acidic and neutral aqueous conditions. Promising candidates exhibiting enhanced redox profiles and solubility were further explored in preliminary tests using aqueous redox flow half-cells.	viologen; two-step reversible reduction;