CYCLOPHANES WITH SELF-RECOGNIZING COMPONENTS

High dilution techniques have been employed to construct a series of c harged flexible cyclophanes comprised of pi-electron-rich hydroquinone and pi-electron-deficient bipyridinium residues linked by polyether s pacer units of varying length: significant conformational changes, lea ding to intramolecular and intermolecular interactions between the pi- donors and pi-acceptors, have been observed-as evidenced by X-ray crys tallographic and variable temperature H-1 NMR and 2D ROESY spectroscop ic investigations-within the series of the cyclophanes both in the sol id and solution states as a result of increasing the lengths of the po lyether spacer units.