External stimulus-responsive supramolecular structures formed by a stilbene cyclodextrin dimer

Cyclodextrin (CD) based supramolecular complexes have been prepared using a stilbene bis(beta-CD) dimer and a ditopic adamantyl guest. The conformation of the stilbene bis(beta-CD) dimer in aqueous solutions could be photochemically controlled. The ROESY spectra of the beta-CD dimer with the adamantyl dimer showed NOE between the protons of adamantyl moieties and the inner protons of the CD. When the host cycloclextrin dimer was in trans conformation, supramolecular dimers or small assemblies are formed in solutions, whereas in its cis conformation supramolecular linear polymers with high molecular weight were observed. Thus the structure of the supramolecular polymers could be controlled by an external stimulus.