Cation-? interaction between the trimethylammonium moiety and the aromatic ring within lndole-3-acetic acid choline ester, a model compound for molecular recognition between acetylcholine and its esterase: an X-ray study

Abstract
X-Ray analysis of indole-3-acetic acid choline ester, a model compound for molecular recognition between the neurotransmitter acetylcholine and its esterase, shows that the quaternary trimethylammonium group is folded back to make a close contact with the indole ring through the cation–π interaction; 1H NMR spectroscopy confirms this type of interaction also occurs in solution.