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Cucurbit[7]uril complexations of Good's buffers

Author:
Selinger, Allison J., Macartney, Donal H.
Source:
RSC advances 2017 v.7 no.67 pp. 42513-42518
ISSN:
2046-2069
Subject:
ammonium, aqueous solutions, buffers, macrocyclic compounds, nuclear magnetic resonance spectroscopy, pH, sulfonates, zwitterions
Abstract:
The cucurbit[7]uril (CB[7]) host–guest complexations of a series of zwitterionic “Good's” biological pH buffers have been investigated in aqueous solution by means of ¹H NMR spectroscopy. The cyclohexylammonium buffers bind very strongly (KCB[₇] = 10⁷ to 10⁸ dm³ mol⁻¹), while the morpholinium (10² to 10³ dm³ mol⁻¹) and piperazinium (10³ to 10⁴ dm³ mol⁻¹) buffers have binding constants several orders of magnitude smaller. The binding constants increase as the distance between the ammonium and sulfonate groups increases. The pKₐ of 2-(cyclohexylammonio)ethanesulfonate (CHES) increases by 3.1 units upon complexation by CB[7].
Agid:
6421538