We are happy that we just published a new paper1 in a special issue of the Journal of Solid State Electrochemistry dedicated to the 60th birthday of Prof. Frank Marken from the University of Bath. The special issue is edited by Frank’s former supervisor, the legendary Prof. Richard G. Compton, and his former Oxford colleague Prof. Jay D. Wadhawan.
In the paper we teamed up with theoreticians Adam Kubas and Dariusz Piekarski to investigate the redox properties of 8-aminoquinoline (8AQ). 8AQ is a molecule that serves as building block for many medicinal molecules, but its redox properties was relatively poorly understood. Combining spectroelectrochemical measurements, with cyclic voltammetry and quantum chemical calculations let us identify the different oxidation pathways at different pH. At low pH, 8AQ exist in two hydrogenated tautomers with quite similiar energies. We found a remarkable similarity between the measured and calculated UV-Vis spectra, which gave us confidence that the reaction scheme we described.
For the reduction processes, we found that they happen at quite low potential and that the mechanism seem to be the same at all investigated pH values. Also here, based on comparison of calculated UV-Vis spectra and experimental spectroelectrochemical data, we could identify the two most likely of six possible products.
We also showed that a mysterious second oxidation peak that were seen in some publications on other aminoquinolines, but not all, was an artefact of adsorbed AQ. Interestingly, the peak is only visible on properly cleaned electrodes.
In summary, the paper shows the great advantage of the combination of experimental techniques with quantum chemical studies and how this can advance our understanding of the electrochemical phenomena. Our research finally suggests that drugs containing 8AQ are unlikely to undergo reduction reactions in the human body because the required conditions are not present. However, these drugs might undergo oxidation reactions due to to the activity of certain enzymes in the body.
- M. Wiloch, D. Piekarski, N Baran, A. Kubas, M. Jönsson–Niedziółka
Spectroelectrochemical properties of 8-aminoquinoline: voltammetric and computational studies, Accepted, J. Solid State Electrochem. (2025). (link)(Preprint on ChemRxiv)
