Volume 185, 2015

Determination of the kinetics underlying the pKa shift for the 2-aminoanthracenium cation binding with cucurbit[7]uril

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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Article information

Article type
Paper
Submitted
27 May 2015
Accepted
19 Jun 2015
First published
19 Jun 2015
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2015,185, 381-398

Determination of the kinetics underlying the pKa shift for the 2-aminoanthracenium cation binding with cucurbit[7]uril

S. S. Thomas and C. Bohne, Faraday Discuss., 2015, 185, 381 DOI: 10.1039/C5FD00095E

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