Physicochemical Study of a Metastable-State Photoacid

A photoacid that possesses a metastable acidic state induced by visible light is studied. Previous work showed that this photoacid can reversibly produce a large pH change capable of controlling chemical reactions, altering material properties, and killing bacteria. In this work, we studied the rela...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2013-12, Vol.117 (49), p.13101-13104
Main Authors: Johns, Valentine K, Wang, Zhuozhi, Li, Xinxue, Liao, Yi
Format: Article
Language:English
Subjects:
Bacteria
Chemical reactions
Ethanol
Ethyl alcohol
Mathematical analysis
Rate constants
Reaction kinetics
Solvents
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Summary:A photoacid that possesses a metastable acidic state induced by visible light is studied. Previous work showed that this photoacid can reversibly produce a large pH change capable of controlling chemical reactions, altering material properties, and killing bacteria. In this work, we studied the relaxation kinetics of the metastable acidic state in different solvents including water, ethanol, and DMSO. In all of these solvents, the kinetic data can be fitted well to a second-order rate equation, which indicates that protonation is involved in the rate-limiting step. The rate constants in water, ethanol, and DMSO are 73, 1.6, and 0.034 M–1 s–1, respectively. The slow relaxation in DMSO allowed us to fully characterize the structure of the metastable acidic state using proton NMR. We also measured the quantum yield of the photoreaction, which is as high as 0.37.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp409111m