Speaker: Dr. Soumyadip Mondal
Institute of Science and Technology Austria
(ISTA)
Title: "Individual Marcus-type kinetics controls singlet and
triplet oxygen evolution from superoxide."
Day and Date: Wednesday, February 04, 2026
Time: 11.00 am.
Venue: Room no. 350, Chemistry Department
Second floor, Annex
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Hosted by Prof. Arnab Dutta
Abstract Oxygen evolution from superoxide is a critical aspect of oxygen redox chemistry. Superoxide experiences
a broad range of oxidizing conditions to liberate oxygen. A very widely occurring type of oxidation is
disproportionation in response to superoxide being highly unstable in most environments1
. This reaction
occurs in both protic (aqueous) environments2 and aprotic ones with relatively strong Lewis acids such as
Li+ and Na+ 3,4 . During disproportionation (2 O2
– → O2 + O2
2–
), one superoxide is reduced to peroxide while
the other is oxidized to form dioxygen, which may be 3O2 or 1O2
5
. Examples include cellular respiration6
and batteries3,7,8. Relative 3O2 and 1O2 yields and kinetics of superoxide disproportionation, and superoxide
oxidation more generally, are therefore fundamental to these systems9
. However, it is still unclear what
controls the extent to which 1O2 or 3O2 evolves during the oxidation of superoxide to dioxygen.
I will talk about our recent findings that the driving force for superoxide oxidation to 3O2 and 1O2 oxygen
to be the common descriptor determining the spin state10. This follows individual Marcus normal and
inverted region behavior.
1O2 can only become significant since the kinetics for 3O2 evolution slows down
in its inverted region. The results help clarify previously inconclusive findings about 1O2 formation from
superoxide, including through interaction with chemical oxidants, and proton and Lewis acid-driven
disproportionation. Recognizing what controls 3O2 and 1O2 formation from superoxide should enable
strategies to suppress 1O2 in human-made redox systems, where 1O2 is, in most cases, harmful. The results
expand knowledge on the electrogeneration of excited species more generally11 and pose new open
questions, such as the origin of differing maximum kinetics for the ground and excited states. The findings
provide insights into understanding and controlling spin states and kinetics in oxygen redox chemistry,
with implications for fields including life sciences and energy storage.