Reactivities of 1,2-, 1,3-, and 1,4- Dihydroxynaphthalenes toward Electrogenerated Superoxide in N,N-Dimethylformamide through Proton-coupled Electron Transfer

11 April 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


We have carried out an electrochemical and theoretical study on the reactivity of 1,2-, 1,3-, and 1,4-dihydroxynaphthalenes (1nH2NQ, n = 2, 3, 4) toward electrogenerated superoxide radical anion (O2•−) in N,N-dimethylformamide. Cyclicvoltammetry and in situ electrolytic electron spin resonance measurements revealed that the quinone–hydroquinone π-conjugation plays an important role in a successful O2•− scavenging by 12H2NQ and 14H2NQ through proton-coupled electron transfer (PCET) reaction. The reactivities of 12H2NQ and 14H2NQ toward O2•− were mediated by the ortho- (catechol) or para-diphenol (hydroquinone) moieties, as experimentally confirmed in comparative analyses with catechol, hydroquinone, and 13H2NQ, aided by density functional theory (DFT) calculations. The electrochemical and DFT results suggested that a concerted PCET mechanism involving two-proton transfers and one-electron transfer proceeds with a superior kinetic, demonstrating a successful O2•− scavenging by 12H2NQ and 14H2NQ. Furthermore, a subsequent electron transfer between molecular dioxygen and product-naphthoquinone-radicals was observed, where O2•− was generated. The DFT analysis suggested that the spin distribution on the planar naphthalene ring embodies the superior kinetics of the PCET and the subsequent generation of O2•− from dioxygen demonstrated in the electrochemical results.


Proton-coupled electron transfer
Superoxide radical anion
Density functional theory

Supplementary materials

Supplementary data for Reactivities of 1,2-, 1,3-, and 1,4-Dihydroxynaphthalenes toward Electrogenerated Superoxide in N,N-Dimethylformamide through Proton-coupled Electron Transfer
CV parameters; Scheme of in situ electrolytic ESR spectral system; Calculated geometries of complexes (PRC, TS, and PC) formed along the 2PCET between 12H<sub>2</sub>NQ and O<sub>2</sub><sup>•−</sup>; Energy profile along IRC of 2PCET between catechol and O<sub>2</sub><sup>•−</sup>


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.