We describe here the synthesis and characterization of a molecular receptor that forms kinetically and thermodynamically stable host-guest complexes in water. This cavitand-based host is composed of a preorganized aromatic pocket whose rim is decorated with four negatively charged carboxylate groups. (1)H NMR and isothermal titration calorimetry have been used to characterize the behavior of the resulting complexes in response to changes in pH, buffer identity, and salt concentration and in the presence of sodium dodecyl sulfate micelles.

Four negative charges at the entrance of a deep pocket, lined with aromatic residues are the features of a synthetic receptor which shows high affinity for acetylcholine (see picture) and choline in water. The size, shape, and charge recognition elements featured in the natural enzyme acetylcholinesterase are reproduced by the synthetic receptor.

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Vier negative Ladungen bewachen den Eingang zu der tiefen, mit aromatischen Systemen ausgekleideten Tasche eines synthetischen Rezeptors (siehe Bild), der Acetylcholin und Cholin in wässriger Lösung mit hoher Affinität bindet. In Größen‐, Form‐ und Ladungserkennung entspricht das synthetische Modell dem natürlich vorkommenden Enzym.