0000000001311181
AUTHOR
Jacques Le Moigne
Protonation of a Spherical Macrotricyclic Tetramine: Water Inclusion, Allosteric Effect, and Cooperativity
The spherical macrotricyclic cryptand tetramine "C24" (1) displays remarkable protonation behaviour. It undergoes protonation in four successive steps for which pKa values of 11.17±0.05, 10.28±0.04, 6.00±0.06 and 3.08±0.08 have been determined at 298 K. The unusually close values for the first two protonations provide evidence for the encapsulation of a water molecule serving as effector for the second protonation, which is consistent with earlier observations that the exchange of protons bound in the diprotonated species with solvent protons is unusually slow and that 17 O NMR spectra show the presence of an oxygen centre in the same species quite distinct from that of solvent water. Encap…
CCDC 1501082: Experimental Crystal Structure Determination
Related Article: Ernest Graf, Jack Harrowfield, Jean-Pierre Kintzinger, Jean-Marie Lehn, Jacques Le Moigne, Kari Rissanen|2018|ChemPlusChem|83|605|doi:10.1002/cplu.201700557