Determination of the kinetics underlying the pKa shift for the 2-aminoanthracenium cation binding with cucurbit[7]uril
Date
2015-06
Authors
Thomas, Suma S.
Bohne, Cornelia
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Publisher
Faraday Discussions
Abstract
The binding dynamics of the 2-aminoanthracenium cation (AH+) and 2-aminoanthracene (A) with cucurbit[7]uril (CB[7]) was studied using stopped-flow experiments. The kinetics was followed by measuring the fluorescence changes over time for AH+ and A, which emit at different wavelengths. The studies at various pH values showed different mechanisms for the formation of the AH+@CB[7] complex, with this complex formed either by the binding of AH+ or by the initial binding of A followed by protonation. In the latter case, it was possible to determine the protonation ((1.5 ± 0.4) × 109 M−1 s−1) and deprotonation (89 ± 7 s−1) rate constants for complexed A/AH+, which showed that the pKa shift of +3.1 for A/AH+ in the complex is mainly due to a lower deprotonation rate constant.
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Citation
Thomas, S., Bohne, C. (2015). Determination of the kinetics underlying the pKa shift for the 2-aminoanthracenium cation binding with cucurbit[7]uril. Faraday Discussions, 185, 381-398. doi: 10.1039/c5fd00095e