Redox properties of flavin derivatives: A Comparative study

Flavins as cofactors in natural systems as well as their artificial analogues used in catalysis are unique due to their specific redox properties. Our study provides the first direct comparison of the electrochemical behavior of various flavin derivatives:  in addition to derivatives of the natural flavins possessing isoalloxazine structure, the experiments were oriented also to their analogues: alloxazines, deazaflavins and flavinium or deazaflavinium salts. We focused on the redox properties of six series of the mentioned flavin types with the stress on the substitution in positions 7 and 8 in connection with the structure of the core using various solvents and electrode materials. In addition to the study by cyclic and rotating disk voltammetry (CV and RDV), we turned our attention on the in-situ measurements of EPR spectra of radicals generated electrochemically. Experiments are accompanied by theoretical treatment enabling interpretation of electrochemical data and prediction of redox potential values of newly designed flavin derivatives.