Synthesis of a rotaxane by self-inclusion of the guest molecule bearing permethylated cyclodextrins

Abstract

Insulated conjugated molecules have a high potential application to organic electronics for reducing their aggregations and enhancing their fluorescence efficiency, chemical stability, and solubility. Herein, we describe a synthetic methodology of a highly insulated conjugated molecule via double self-inclusion of a guest molecule bearing two permethylated cyclodexitrins and fixation of the pseudorotaxane with two [1]rotaxanes as stopper units by Sonogashira coupling reaction in 50% aqueous MeOH. The structural conformation of the insulated conjugated molecule that four macrocycles are fixed to an axle molecule in a [5]rotaxane system was investigated by general NMR techniques. The corresponding reference compounds that the axle molecule is insulated with two macrocycles or fully naked were also synthesized in ⁱPr₂NH-THF systems. The shielding effects of macrocycles for an axle fluorophore of the rotaxane and the reference compounds were estimated by Stern-Volmer titration experiment.