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4NPOH.pdf (948.6 kB)
Time-Resolved Study of Light-Induced Ground State Proton Transfer from Acid Medium to 4-Nitrophenolate
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
submitted on 12.09.2020 and posted on 14.09.2020by Leandro Scorsin, Leticia Martins, Haidi Fiedler, Faruk Nome, RENE NOME
In the present work, we
study the transient laser-induced formation of 4-nitrophenolate (4-NPO-)
in the ground electronic state and subsequent proton transfer reaction with
acetic acid and water with numerical calculations and laser flash photolysis. We
employ the Debye-Smoluchowski spherically-symmetric diffusion model of photoacid
proton transfer to determine experimental conditions for studying thermally
activated chemical reactions in the ground electronic state. Numerically calculated
protonation and deprotonation probabilities for 4-NPO- and
4-nitrophenol (4-NPOH) in both ground and excited states showed the feasibility
of efficiently producing the ground state anion in the photoacid cycle. We
performed laser flash photolysis measurements of 4-NPOH to characterize the
photo-initiated ground state protonation and deprotonation rate constants of
4-NPO-/4-NPOH as a function of acetic acid, pH, temperature and
viscosity. Overall, the work presented here shows a simple way to study fast
competing bimolecular proton transfer reactions in non-equilibrium conditions
in the ground electronic state (GSPT).