Structure−Reactivity Relationship in Interlocked Molecular Compounds and in Their Supramolecular Model Complexes

Abstract

Examination of the pseudorotaxane-like geometries adopted in the solid state by a series of 1:1 complexes revealed significant differences in the hydrogen bonding interactions between oxygen atoms in some hydroquinone-based guests carrying polyether/polyester functions and the acidic hydrogen atoms on the bipyridinium units of the hostcyclobis(paraquat-p-phenylene). These differences are reflected directly in the stabilities of the complexes in solution and dramatic changes in the magnitudes of their association constants (Ka values ranging from 130 to 4300 M-1 in MeCN at 25 °C) are observed upon varying the location of the carbonyl ester function(s) along the polyether/ester chains. A similar effect (Ka values ranging from 5 to 730 M-1 in Me2CO at 25 °C) was observed in the binding of paraquat as its bipyridinium bis(hexafluorophosphate) salt by analogous macrocyclic hydroquinone-based mono- and bis-lactones. Investigations of the kinetics of hydrolyses of the ester functions revealed thatwhile inert in ...