Complexes from Polyazacyclophanes, Fluorescence Indicators, and Metal Cations— An Example of Allosterism through Ring Contraction

摘要

Synthetic host guest systems tan be relatively easily designed to have a receptor containing several conformationally strongly coupled binding sites that may also bind organic substrates. We report here on ternary complexes in which the cavity tor a lipophilic guest molecule is fitted specially by contraction of the hollow space, which is initiated by the binding of metal cations. Molecular mechanics simulations (force-field CHARMm) of polyazaeyclophanes 1 and 2 (Scheme 1) obtained by published procedures- indicate an almost spherical shape with a wide cavity in the absence of complexing metal cations (Fig. la).